WO2023095800A1 - Electret and electret filter - Google Patents
Electret and electret filter Download PDFInfo
- Publication number
- WO2023095800A1 WO2023095800A1 PCT/JP2022/043219 JP2022043219W WO2023095800A1 WO 2023095800 A1 WO2023095800 A1 WO 2023095800A1 JP 2022043219 W JP2022043219 W JP 2022043219W WO 2023095800 A1 WO2023095800 A1 WO 2023095800A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electret
- zinc oxide
- oxide particles
- value
- filter
- Prior art date
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- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 claims abstract description 148
- 239000002245 particle Substances 0.000 claims abstract description 111
- 239000011787 zinc oxide Substances 0.000 claims abstract description 74
- 238000005424 photoluminescence Methods 0.000 claims abstract description 31
- 238000005259 measurement Methods 0.000 claims abstract description 27
- 229920005672 polyolefin resin Polymers 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims description 87
- 239000000835 fiber Substances 0.000 claims description 39
- -1 nitrogen-containing compound Chemical class 0.000 claims description 30
- 230000028161 membrane depolarization Effects 0.000 claims description 29
- 239000007788 liquid Substances 0.000 claims description 21
- 239000004745 nonwoven fabric Substances 0.000 claims description 20
- 239000002657 fibrous material Substances 0.000 description 21
- 230000000844 anti-bacterial effect Effects 0.000 description 19
- 239000000463 material Substances 0.000 description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 18
- 239000004594 Masterbatch (MB) Substances 0.000 description 16
- 229920005989 resin Polymers 0.000 description 15
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- 238000007600 charging Methods 0.000 description 14
- 238000011156 evaluation Methods 0.000 description 13
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- JYEUMXHLPRZUAT-UHFFFAOYSA-N 1,2,3-triazine Chemical group C1=CN=NN=C1 JYEUMXHLPRZUAT-UHFFFAOYSA-N 0.000 description 4
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- RKMGAJGJIURJSJ-UHFFFAOYSA-N 2,2,6,6-tetramethylpiperidine Chemical group CC1(C)CCCC(C)(C)N1 RKMGAJGJIURJSJ-UHFFFAOYSA-N 0.000 description 3
- 150000001336 alkenes Chemical class 0.000 description 3
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- RYPKRALMXUUNKS-UHFFFAOYSA-N 2-Hexene Natural products CCCC=CC RYPKRALMXUUNKS-UHFFFAOYSA-N 0.000 description 2
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000000843 anti-fungal effect Effects 0.000 description 2
- 238000000149 argon plasma sintering Methods 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 description 2
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- 239000003484 crystal nucleating agent Substances 0.000 description 2
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- 125000001841 imino group Chemical group [H]N=* 0.000 description 2
- 239000000314 lubricant Substances 0.000 description 2
- HQKMJHAJHXVSDF-UHFFFAOYSA-L magnesium stearate Chemical compound [Mg+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O HQKMJHAJHXVSDF-UHFFFAOYSA-L 0.000 description 2
- 239000008204 material by function Substances 0.000 description 2
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- 239000004750 melt-blown nonwoven Substances 0.000 description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 2
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- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 1
- LEVFXWNQQSSNAC-UHFFFAOYSA-N 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-hexoxyphenol Chemical compound OC1=CC(OCCCCCC)=CC=C1C1=NC(C=2C=CC=CC=2)=NC(C=2C=CC=CC=2)=N1 LEVFXWNQQSSNAC-UHFFFAOYSA-N 0.000 description 1
- DOTYDHBOKPPXRB-UHFFFAOYSA-N 2-butyl-2-[(3,5-ditert-butyl-4-hydroxyphenyl)methyl]propanedioic acid Chemical compound CCCCC(C(O)=O)(C(O)=O)CC1=CC(C(C)(C)C)=C(O)C(C(C)(C)C)=C1 DOTYDHBOKPPXRB-UHFFFAOYSA-N 0.000 description 1
- OWXXKGVQBCBSFJ-UHFFFAOYSA-N 6-n-[3-[[4,6-bis[butyl-(1,2,2,6,6-pentamethylpiperidin-4-yl)amino]-1,3,5-triazin-2-yl]-[2-[[4,6-bis[butyl-(1,2,2,6,6-pentamethylpiperidin-4-yl)amino]-1,3,5-triazin-2-yl]-[3-[[4,6-bis[butyl-(1,2,2,6,6-pentamethylpiperidin-4-yl)amino]-1,3,5-triazin-2-yl]ami Chemical compound N=1C(NCCCN(CCN(CCCNC=2N=C(N=C(N=2)N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)C=2N=C(N=C(N=2)N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)C=2N=C(N=C(N=2)N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)=NC(N(CCCC)C2CC(C)(C)N(C)C(C)(C)C2)=NC=1N(CCCC)C1CC(C)(C)N(C)C(C)(C)C1 OWXXKGVQBCBSFJ-UHFFFAOYSA-N 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- 229910000906 Bronze Inorganic materials 0.000 description 1
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 description 1
- 241000588724 Escherichia coli Species 0.000 description 1
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerol Natural products OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004734 Polyphenylene sulfide Substances 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- 241000191967 Staphylococcus aureus Species 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000006096 absorbing agent Substances 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
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- YACLQRRMGMJLJV-UHFFFAOYSA-N chloroprene Chemical compound ClC(=C)C=C YACLQRRMGMJLJV-UHFFFAOYSA-N 0.000 description 1
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- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 1
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- 230000002999 depolarising effect Effects 0.000 description 1
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- 229910010272 inorganic material Inorganic materials 0.000 description 1
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- RTWNYYOXLSILQN-UHFFFAOYSA-N methanediamine Chemical compound NCN RTWNYYOXLSILQN-UHFFFAOYSA-N 0.000 description 1
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- HRYSOBDFNHXNTM-UHFFFAOYSA-N n-butylbutan-1-amine;1,3,5-triazine Chemical compound C1=NC=NC=N1.CCCCNCCCC HRYSOBDFNHXNTM-UHFFFAOYSA-N 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L9/00—Disinfection, sterilisation or deodorisation of air
- A61L9/01—Deodorant compositions
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L9/00—Disinfection, sterilisation or deodorisation of air
- A61L9/16—Disinfection, sterilisation or deodorisation of air using physical phenomena
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C3/00—Separating dispersed particles from gases or vapour, e.g. air, by electrostatic effect
- B03C3/28—Plant or installations without electricity supply, e.g. using electrets
-
- D—TEXTILES; PAPER
- D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
- D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
- D04H3/00—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length
- D04H3/08—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating
- D04H3/16—Non-woven fabrics formed wholly or mainly of yarns or like filamentary material of substantial length characterised by the method of strengthening or consolidating with bonds between thermoplastic filaments produced in association with filament formation, e.g. immediately following extrusion
Definitions
- the present invention relates to electrets and electret filters.
- porous filters for dust collection, protection, and ventilation.
- filters made of fibrous materials have advantages of high porosity, long life and low airflow resistance.
- a nonwoven fabric is preferably used as a filter made of such a fibrous material.
- Electrets are materials capable of sustaining and utilizing electrostatic forces through various manipulations of various dielectric materials. Filters that are charged and formed as electrets are widely used as electret filters.
- the inventor of the present invention focused on zinc oxide as an inorganic particle having functionality, and studied compatibility between its functionality and electret properties. However, we faced the problem that it could not be handled in the same way as the conventional electret.
- the present invention has been made in view of the above problems, and an object thereof is to provide an electret and an electret filter containing zinc oxide particles with excellent charge stability.
- an electret and an electret filter containing specific zinc oxide particles can achieve both functions of the electret and zinc oxide particles and have excellent properties. arrived at the invention.
- the invention is shown below.
- the value of a/b is 0.3 or less, where a is the maximum value of the depolarization current at 50 to 100°C measured by the TSC method, and b is the maximum value of the depolarization current at 100°C or higher. 3.
- the electret according to 1 or 2 above characterized in that: 4. 4.
- the electret according to any one of 1 to 4 above which is charged by a liquid contact method.
- 7. The electret filter as described in 6 above, wherein the filter medium quality factor QF value is 1.3 mmAq -1 or more.
- the electret of the present invention uses a polyolefin resin that is hydrophobic and has high electrical resistance, from the viewpoint of the degree of freedom of shape and the electret's charge stability.
- polyolefin resins include homopolymers of olefins such as ethylene, propylene, butylene, hexene, octene, butadiene, isoprene, chloroprene, methyl-1-pentene, and cyclic olefins, and two or more of the above olefins and halogenated olefins.
- a copolymer such as One type of polyolefin resin may be selected and used alone, or two or more types may be selected and used in combination.
- the polyolefin resin preferably contains at least one selected from polyethylene, polypropylene and polymethylpentene, and more preferably contains polypropylene.
- the content of the polyolefin resin in 100% by mass of the electret is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and 95% by mass or more. is particularly preferable, and 97% by mass or more is most preferable.
- the resin used in the present invention preferably has a stereoregularity of 85% or more, more preferably 90% or more, still more preferably 90% or more, and most preferably 95% or more.
- isotactic or syndiotactic can be preferably used.
- two or more types of polypropylene it is preferable that one or more types are contained in the contained polyolefin.
- polyolefin resin used in the present invention those having various molecular weight distributions and viscosity characteristics can be preferably used, and the branched chain structure and the like can be selected according to the required final shape and workability. . Also in this case, it is preferable to use one or a combination of two or more.
- the electret in the present invention is characterized by containing zinc oxide particles in polyolefin resin.
- zinc oxide particles have the desired properties, it is also preferable to use one or a combination of two or more of them depending on the required properties.
- Specific functions of zinc oxide particles include dielectric properties, opacity, coloring properties, antibacterial properties, antifungal properties, odor removing properties, antiviral properties, and antiallergenic properties.
- the shape of the zinc oxide particles used in the present invention may be plate-like, needle-like, rectangular, spherical, elliptical, or any other shape. These may be monocrystalline and polycrystalline primary particles, secondary particles with strong or weak bonds. For the purpose of improving the charge stability of the electret, it is preferably spherical, rectangular, or tabular with a small aspect ratio. It is preferred that the particles are primary particles, and most preferably the primary particles have the following sizes. Unintended grain refinement is suppressed during extrusion and mixing processing, and the surface area can be reduced, so that a composition preferable for maintaining electret properties can be obtained.
- the average particle size of the zinc oxide particles used in the present invention ranges from 0.1 ⁇ m to 10 ⁇ m. It is preferably 0.1 ⁇ m to 8 ⁇ m, more preferably 0.1 to 5 ⁇ m, even more preferably 0.1 to 3 ⁇ m, most preferably 0.1 to 2 ⁇ m. If the particle size is small, there is concern about handling as nanoparticles, which is an important characteristic in dealing with various nano-substance regulations. On the other hand, if it is too large, the dispersibility becomes poor and it is necessary to add a large amount in order to develop the functionality. In addition, the polyolefin resin containing zinc oxide particles tends to become brittle and deteriorate in workability.
- the amount of zinc oxide particles to be added can be preferably adjusted according to the required functionality. is 0.05 to 7% by mass, more preferably 0.1 to 5% by mass, most preferably 0.15 to 3% by mass. If it is too small, the antibacterial effect will be insufficient, and if it is too large, workability and mechanical strength will be lowered.
- the zinc oxide particles used in the present invention are characterized by having specific characteristics in photoluminescence (PL) measurement, thereby achieving both electret characteristics and functionality due to the addition of zinc oxide particles. Specifically, it is excited by laser light with a wavelength of 325 nm, and luminescence obtained as photoluminescence is detected with a CCD detector in a wavelength range of 350 to 700 nm.
- the ratio (B/A) of the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm and the photoluminescence intensity B in the wavelength range of 500 nm to 700 nm. is 0.1 or less.
- B/A is preferably 0.09 or less, more preferably 0.05 or less, still more preferably 0.025 or less, and most preferably 0.01 or less.
- the intensity is obtained by correcting the detection sensitivity of the CCD with the detection sensitivity for each wavelength, and allows relative comparison as the amount of photons for each wavelength.
- the maximum height in each of the above ranges is used as the value of A and B. When it exists as a peak, it means the peak value, and when it exists as a tail, it means the maximum value existing on the peak boundary side. It is interpreted as a spectrum of continuously occurring photoluminescence, and is clearly distinguished from large spike-like noise and measurement abnormal values.
- the smaller the B/A value affects charge stability and electret properties due to mechanisms such as the electrical resistivity of the zinc oxide particles themselves or the resin composition that becomes the electret, the oxidation of the electret, and the photochemical reaction. it is conceivable that.
- the detection sensitivity and baseline noise value are low and stable, and the noise value and the measured value obtained by photoluminescence are strictly different.
- a microscopic system capable of measuring in a minute area.
- the method of adding zinc oxide particles to the polyolefin resin used in the present invention is not particularly limited as long as the desired properties can be obtained. Examples include a method of adding zinc oxide particles or precursors during production, a method of adding zinc oxide particles or precursors during molding, and a method of melting and adhering to the surface of molded polyolefin, which are used alone or in combination. be able to.
- zinc oxide particles having predetermined properties are added in advance to the resin during masterbatch or compound production, or they are added together with the resin into the extruder during the production of molded articles such as fibrous materials, films, and extruded materials.
- a method of melt-mixing is preferably used.
- the resin and zinc oxide particles may be mixed in advance using a tumbler or various mixers, or may be separately supplied using a feeder, which can be preferably selected according to the characteristics of the apparatus.
- the resin and the zinc oxide particles may be introduced simultaneously, or the zinc oxide particles may be mixed into the molten resin in the middle.
- a dispersant can be used to improve the dispersibility of the zinc oxide particles during melt mixing and molding.
- the material is not particularly limited as long as it is suitable for exhibiting dispersibility, electret properties, and functionality of zinc oxide particles.
- Those having a hydrophilic group such as an ether group and a hydrophobic group such as a hydrocarbon group and a perfluoro group in a single molecule can be preferably used.
- the molecular weight an appropriate one can be used, taking into account the viscosity and the size and dispersibility of the zinc oxide particles of interest. It may also be substantially the same chemical substance as the surfactant.
- the dispersant it is preferable to attach it to the zinc oxide particles in advance or to add it during mixing.
- the dispersant is a compound containing an ester group
- glycerin fatty acid esters, sorbitan fatty acid esters, fatty acid esters, etc. can be exemplified, and the affinity and melting point of the zinc oxide particles and polyolefin can be improved. It can be used with consideration.
- the melting point of the dispersant mixed during melting is preferably the same or lower than that of the electret polyolefin resin, more preferably 20° C. or more, in consideration of the melting and dispersing functions in the extruder. , and more preferably 50°C or higher.
- the dispersant When the dispersant has a significantly high reactivity with the zinc oxide particles and/or has a higher melting point than the polyolefin resin which is the main component of the electret, it is pre-oxidized using coating or heat mixing in a solution or precursor state. It is also preferable to attach it to the zinc particle surface.
- the surface of the zinc oxide particles with an organic or inorganic material, and various silane coupling agents, organic acids, nitrogen-containing organic compounds, inorganic elements and inorganic oxides can be used. can be done.
- various silane coupling agents, organic acids, nitrogen-containing organic compounds, inorganic elements and inorganic oxides can be used. can be done.
- the molecular structure, viscosity, and flow characteristics of the resin material that serves as the base material for manufacturing the masterbatch or compound that mixes the zinc oxide particles can be adjusted as necessary.
- adjustment of affinity and wettability with zinc oxide particles, adjustment of electret and resin viscosity on the side to be added which is the final form, dispersion of zinc oxide particles, adjustment of surface precipitation and fixed state, phase separation structure examples include the purpose of regulation, the uneven distribution of zinc oxide particles, and the expression of other types of functions. These can be used without being limited to polyolefin resins.
- the present invention it is also preferable to mix various functional materials in the masterbatch or compound at the same time.
- various functional materials for example, nitrogen-containing compounds, various antioxidants, heat resistance improvers, and Viscosity and crystallinity modifiers, pigments, lubricants, antiadhesives and the like can be exemplified. It is also preferable to use the same dispersant for the zinc oxide particles and the functional material.
- the present invention is an electret made of polyolefin resin containing zinc oxide particles.
- Conventionally known methods can be used for electretization, for example, a method of electric field polarization at room temperature or at an elevated temperature, a method of giving positive and negative charges by contacting with electrodes and energizing, photoelectric conversion by light or radiation, etc.
- Methods of imparting electric charge using effects methods of imparting electric charge by contact or friction of liquids or solids, methods of imparting electric charge by crushing or splitting, methods of imparting electric charge by collision of charged particles or charged ions, bending, phase change, etc. can be exemplified.
- the liquid contact method in which the material is electretized by contact with water or a liquid containing water, is preferable. Further, by adding a nitrogen-containing compound as an electrification enhancer, it becomes possible to effectively impart an electric charge.
- the liquid contact method is not particularly limited as long as it can be effectively electretized.
- a method of contacting and passing a liquid in the thickness direction, then removing and drying is preferably used.
- the method of contacting and passing the liquid is not particularly limited as long as the desired effect can be obtained, but methods such as injection, injection, condensation, and suction can be used. Heating using suction, atmospheric pressure reduction, heat, electromagnetic waves, or the like can be used.
- a combination of spraying, vacuum and drying is preferred as a continuous process step.
- each treatment of the liquid contact method is shown below.
- the material to be charged is a fibrous material such as non-woven fabric
- the fibrous material is placed on a mesh support having an air permeability of 50 to 400 cm 3 /cm 2 /sec, and water is sprayed from above.
- the air permeability can be measured using a frandil type tester described in JIS L1096.
- the above-mentioned net-like support is specifically a porous structure made of a fabric of metal yarn or plastic yarn, and includes woven shapes such as plain weave, twill weave, and satin weave.
- metal materials include stainless steel and bronze
- plastic materials include polypropylene, polyester, polyurethane, nylon, and polyphenylene sulfide.
- water is jetted from a nozzle placed several cm above the object to be charged at a pressure sufficient to wash and pass the water in the thickness direction.
- Sufficient pressure is not specified, but varies depending on the shape of the nozzle hole, the basis weight of the charged body, and the manufacturing method.
- the fibrous material to be charged is, for example, a polyolefin melt-blown nonwoven fabric with a basis weight of 5 to 50 g/m 2 , 0.3 to 3 MPa, for a polyolefin melt blown nonwoven fabric of 50 to 200 g/m 2 , It is preferably ⁇ 4 MPa. If the injection pressure is too high, pinholes and breaks will occur. On the other hand, if the pressure is too low, sufficient water cannot pass through, resulting in insufficient electretization.
- An example of the nozzle is one in which holes with a diameter of 0.05 to 0.2 mm are arranged in one or more rows at a pitch of 0.5 to 3 mm.
- the net-like support is movable and the fibrous material can be conveyed in the longitudinal direction so that the jetting treatment can be continuously performed.
- the conveying speed is not particularly limited, but a preferable range is 1 to 100 m/min.
- the optimum number of injections and the treatment surface are not particularly limited because they depend on the basis weight and average fiber diameter of the fibrous material.
- the negative pressure during suction is not particularly limited, but is preferably -0.01 to -0.5 kPa, for example.
- water can effectively pass through the fibrous material and the amount of retained water can be reduced.
- the hot air drying method is preferable because continuous treatment is possible.
- the temperature must be such that the fibers do not melt or form a film. It is preferably 140° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower.
- the water preferably used in the liquid contact method is not particularly limited as long as it can be effectively electretized, but it is preferably less inorganic salts and high boiling point organic substances, and ion exchange resins, reverse osmosis membranes, etc. It is particularly preferable to use one that has been used and highly purified.
- the pH can also be set in consideration of the solubility, charge polarity, amount of charge, etc., depending on the presence and properties of the zinc oxide particles and charge enhancer. Generally, the range of pH is 1-12, more preferably 2-11, still more preferably 3-10, and most preferably 4-9.
- the present invention by adding a nitrogen-containing compound as an electrification enhancer, electretization by a liquid contact method can be made effective.
- the content of the nitrogen-containing compound in the electret polyolefin resin composition is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, and more preferably 0.75 to 1.5% by mass. 5% by weight is most preferred.
- two or more types of fibers are mixed in the electret, or when two or more types of resin are mixed in one fiber, it refers to the ratio of the nitrogen-containing compound contained in the polyolefin resin.
- the electret contains a resin other than polyolefin, it can be distinguished because the resin other than polyolefin dissolves in solvents and acid bases and has different dyeability, and quantitative methods such as DSC and NMR Even polyolefin resin can be distinguished. If the content of the nitrogen-containing compound is less than 0.1% by mass, the amount of charge is low, resulting in deterioration in filtration characteristics. will be
- the nitrogen-containing compound is not particularly limited as long as desired charging, processing, and mixing properties can be obtained, but it should be a hindered amine compound containing at least one of a 2,2,6,6-tetramethylpiperidine structure and a triazine structure. is preferred, and the hindered amine compound more preferably contains both a 2,2,6,6-tetramethylpiperidine structure and a triazine structure.
- the secondary nitrogen in the piperidine structure can be preferably used in any form such as NH, NOR, and NR.
- hindered amine compound examples include, but are not limited to, poly[ ⁇ 6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl ⁇ (2,2,6,6-tetramethyl-4-piperidyl)imino ⁇ hexamethylene ⁇ 2,2,6,6-tetramethyl-4-piperidyl)imino ⁇ ] (Kimasorb (registered trademark) 944LD, BASF Japan) ), dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethyl-4-piperidine polycondensate (Tinuvin (registered trademark) 622LD, manufactured by BASF Japan), 2-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-2-butylpropanedioate bis[1,2,2,6,6-pentamethyl-4-piperidinyl] (tinuvin (registered trademark
- Chimasorb (registered trademark) 944LD or Chimasorb (registered trademark) containing 2,2,6,6-tetramethylpiperidine structure and triazine structure 2020FD, SABO STAB (registered trademark) UV119 is preferably used.
- the hindered amine compound one type may be used alone, or two or more types may be used in combination.
- the above are examples, equivalent functions and structures may be reagents and industrial raw materials having
- additives such as dispersants and surfactants used to enhance the dispersibility and functionality of zinc oxide particles are water. It is preferable to reduce the elution with respect to, and it is also preferable to combine with the above nitrogen-containing compound. This is because having a polar group has affinity with zinc oxide particles, has compatibility with polyolefin resin, and enhances the hydrophilicity of the electret while maintaining charge stability. Hydrophilicity has a beneficial effect on charging efficiency in liquid contact methods and water-mediated functionalities such as antibacterial, antiviral, and antiallergenic properties.
- polymer having a triazine structure such as Kimasorb (registered trademark) 944LD, Kimasorb (registered trademark) 2020FD, SABO STAB (registered trademark) UV119, and the like. These can be added during masterbatch or compound production, or during molding into final shapes (eg, various fibrous materials).
- the present invention relates to an electret comprising a polyolefin resin containing zinc oxide particles, which may also include, for example, various crystal nucleating agents, fatty acid metal salts, hindered amines different from the above charge enhancers, hindered phenolic antioxidants, phosphorus Antioxidants such as antioxidants, sulfur antioxidants, UV absorbers, pigments, etc. may be added as necessary.
- various crystal nucleating agents such as sorbitol and trisamides, fatty acid magnesium, and fatty acid aluminum are effective in stabilizing the charge of the electret. can be suppressed.
- Addition of a lubricant component composed of fatty acid amide, fatty acid, fatty acid metal salt, and perfluoro derivative is also suitable for suppressing clumps adhering to the nozzle and clogging the nozzle when zinc oxide particles are mixed.
- the TSC (thermally stimulated current) method can be used to evaluate the charge stability of the electret. Specifically, (1) the compact is charged to form an electret. (2) Two electrodes are placed facing each other on both sides of the electret. (3) Connect a high-impedance picoammeter to the electrodes on both sides of the electret. (4) After being placed in a heating bath at 30° C. or lower and short-circuited, the temperature is raised from 25° C. at a rate of 5° C./min to the melting point of polyolefin, which has the highest melting point among the constituent materials of the electret, +10° C. or higher.
- the depolarization temperature of the TSC method is associated with the charge stability of the electret and the performance stability as a filter (for example, Osaka Institute of Technology Bulletin, 66 (1), 1-18, Japanese Patent No. 3199947, etc.).
- the inventors have also found that there is a correlation in charge stability between electrets obtained by the corona charging method used for the TSC method and electrets obtained by the liquid contact method.
- the corona discharge method is used to unevenly distribute the charges (amount and polarity) in the thickness direction so that a sufficient depolarizing current can be observed in the TSC method.
- the atmosphere and sample temperature during charging should be 30° C. or less so as not to affect the measurement results in the TSC method. Since the corona discharge method in the present invention is not intended for surface treatment such as oxidation or etching, it is essential that the equipment and conditions are used for manufacturing and researching electrets.
- the TSC method After performing the charging, start measurement by the TSC method within 10 minutes in an environment with an ambient temperature of 30°C or less.
- an electret that has undergone a history of transportation, storage, heating, etc. after production it is necessary to electretize the electret again by the above-described method in advance and measure it.
- the purpose of the evaluation by the TSC method in the present invention is to evaluate the intrinsic charge stability against heat of the molded product material, and to eliminate the effects of changes in the amount of charge due to various processes and the passage of time. That is, even if the fibrous material or laminate has undergone various histories (time, temperature, etc.), the electret portion can be separated, charged, and then subjected to TSC measurement. It is essential to evaluate In other words, having a high QF and the following a/b ratios are electrets and electret filters with good filtration properties and charge stability.
- a/b (/ is divided is preferably 0.3 or less, more preferably 0.2 or less, and most preferably 0.1 or less. It is important to use a reasonable value with continuity as the data for the maximum current value shown above. Judgment is made based on reasonable figures. If the current polarities are different between the maximum value up to 100° C. and the maximum value above 100° C., the absolute values of both are divided.
- the amount of depolarization charge is expressed as an a/b ratio, and it goes without saying that the amount of depolarization charge during corona charging is preferably large on the high temperature side.
- the depolarization current at 100°C or higher preferably has a peak temperature at which the maximum value and a start temperature are high and has a narrow half-value width.
- the peak temperature is 120°C or higher, more preferably 130°C or higher, and most preferably. 140° C. or higher.
- the rising temperature is preferably 80° C. or higher, more preferably 90° C. or higher, still more preferably 100° C. or higher, and most preferably 110° C. or higher.
- the rise temperature is obtained as the intersection of the tangents of the measured values before and after the peak.
- the electret of the present invention can be made into a molded body of any required shape, but a fibrous material is suitable for use.
- the fibrous materials include fibrous materials such as woven and knitted fabrics, non-woven fabrics, and cotton-like materials made of long fibers or short fibers, and fibrous materials obtained from stretched films, and have an appropriate shape and thickness depending on the application. can be molded into When the electret is used as a filter, it is most preferably a nonwoven fabric.
- Methods for obtaining nonwoven fabrics include a method of sheeting monocomponent fibers, composite fibers such as core-sheath fibers and side-by-side fibers, and short fibers such as split fibers by carding, airlaid, wet papermaking, etc., and a spunbond method using continuous fibers. , a melt blowing method, an electrospinning method, a force spinning method, a method of forming a sheet by a laser stretching method, and the like, and other conventionally known methods can be used.
- long-fiber nonwoven fabrics obtained by a meltblowing method, a melt electrospinning method, a melt force spinning method, a spunbond method, or a laser drawing method are more preferable for electret applications from the viewpoint of not using a spinning oil and a solvent.
- the average fiber diameter (diameter) of the fibers used in the fibrous material of the present invention is preferably 0.001 to 100 ⁇ m, more preferably 0.005 to 20 ⁇ m, and 0.01 to 10 ⁇ m. is more preferred, 0.02 to 5 ⁇ m is particularly preferred, and 0.03 to 3 ⁇ m is most preferred. If the average fiber diameter is larger than 100 ⁇ m, it is difficult to obtain a practical collection efficiency, and the efficiency is greatly reduced during charge decay. When the diameter of the fiber is smaller than 0.001 ⁇ m, it is difficult to impart an electric charge as an electret.
- the fibrous material in the present invention may be a uniform material made of a single manufacturing method and material, or a mixture of two or more materials with different manufacturing methods, materials and fiber diameters. At least a part of the portion having electret properties must be the composition of the present invention for manifestation of the properties.
- the electret of the present invention can be used together with other constituent members as necessary.
- the electret of the present invention is preferably used in combination with, for example, a prefilter layer, a fiber protection layer, a reinforcing member, or a functional fiber layer.
- An electret filter using the electret of the present invention is also included in the scope of the present invention.
- the collection properties of fine particles can also be used to evaluate the charge amount or charge stability of the electret.
- the liquid contact method is effective as an evaluation method when the uneven distribution of charges in the thickness direction is insufficient and direct evaluation by the TSC method is difficult.
- a filter medium quality factor (QF value) as a parameter related to the charge amount
- a method of evaluating charge stability uses the natural logarithmic ratio of transmittance before and after various treatments (herein referred to as performance maintenance ratio).
- the particles those artificially generated may be charged in equilibrium, or atmospheric dust may be used.
- concentration or number may be obtained.
- electrostatic attraction it is preferable that electrostatic attraction is dominant, and as an example, the passing wind speed is 10 cm / s, the pressure difference before and after the sample using a differential pressure gauge, and the diameter using a laser particle counter of 0.3 to 0.
- Particle transmittance [-] (particle number concentration on the downstream side of the sample) / (particle number concentration on the upstream side of the sample)
- Particle collection efficiency [%] (1-particle transmittance [-]) x 100
- Filter media quality factor (QF value) [mmAq -1 ] - (ln (particle permeability [-]) / (ventilation resistance [mmAq]))
- Performance retention rate [-] ln (particle transmittance after treatment [-]) / ln (particle transmittance before treatment [-])
- the value of the filter medium quality factor QF in the above is generally 0.1 or less when fibrous materials that have not been electretized are used.
- the electret is used as a filter, it is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.1 or more, and most preferably 1.2 or more.
- the filter medium quality factor QF is maintained not only immediately after electretization but also after heat treatment.
- the electret of the present invention can have both the function of an electret and the function of zinc oxide particles, and is widely used as a fibrous material and a filter due to its functions such as dust collection, protection, ventilation, antifouling, and waterproofing. be able to.
- a fibrous material and a filter due to its functions such as dust collection, protection, ventilation, antifouling, and waterproofing.
- it can be used not only as a function of the zinc oxide particles alone, but also in an air conditioner combined with a discharge device, an electrostatic precipitator, a light irradiation device, or the like.
- Collection efficiency [%] (1-particle transmittance [-]) x 100 The value measured immediately after the sample was air-dried after charging was taken as the initial collection efficiency.
- QF value Frter material quality factor (QF value)
- QF value The QF value defined below was used as an index of the electret charge amount and filter performance.
- QF [mmAq -1 ] - (ln (particle permeability [-]) / (ventilation resistance [mmAq]) (particle transmittance)
- the sample was attached to an adapter, and the particle transmittance was calculated under the following conditions using a light scattering particle counter KC-01E manufactured by Rion.
- Particles to be evaluated Atmospheric dust particles Wind speed: 10 cm/s
- Efficiency calculation Particle number between 0.3 and 0.5 ⁇ m by light scattering counting method
- Particle transmittance [-] (particle number concentration on the downstream side of the sample) / (particle number concentration on the upstream side of the sample) (ventilation resistance)
- a sample was attached to an adapter, pipes connected to a differential pressure gauge were connected vertically, and ventilation was performed at 10 cm/s to measure airflow resistance (pressure loss) (mmAq) in a state without restriction.
- both electrodes are temporarily short-circuited to set the current value to zero.
- the horizontal axis is the temperature ° C.
- the vertical axis is the current value [-]
- the peak height at 50 to 100 ° C. is a
- the peak height at 100 ° C. to 180 ° C. is b
- average fiber diameter Using a scanning microscope, a plurality of images were obtained with a visual field size of 90 ⁇ m ⁇ 90 ⁇ m, and then 50 fiber diameters were measured so as not to overlap the same fibers. The average fiber diameter was calculated by geometrically averaging the obtained numerical values.
- antibacterial In the antibacterial test, the bacterial liquid absorption method in JIS L 1902 was used to evaluate against Staphylococcus aureus and Escherichia coli.
- Photoluminescence measurement Photoluminescence in the wavelength range of 350 to 700 nm was measured using a microphotoluminescence measuring device under the following conditions. Excitation light: 325 nm (laser), 3 ⁇ W Detector: CCD Measurement temperature: 25°C Objective lens: ⁇ 40
- Zinc oxide particles (b) photoluminescence measurement was performed on a masterbatch in which zinc oxide particles (b) (average particle size 0.8 ⁇ m) were dispersed in polypropylene at a content of 20% by mass.
- the ratio B/A between the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm and the photoluminescence intensity B in the wavelength range of 500 nm to 700 nm was 0.094.
- Example 1> For polypropylene homopolymer of MFR 1300, using the masterbatch of (2) above, zinc oxide particles (a) 0.25% by mass (2.5% by mass as a masterbatch), Chimasorb (registered trademark) 944LD (BASF Japan) (manufacturer) and 0.075% by mass of magnesium stearate were added, and a filament nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 3.0 ⁇ m was obtained using a meltblowing apparatus.
- zinc oxide particles (a) 0.25% by mass (2.5% by mass as a masterbatch), Chimasorb (registered trademark) 944LD (BASF Japan) (manufacturer) and 0.075% by mass of magnesium stearate were added, and a filament nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 3.0 ⁇ m was obtained using a meltblowing apparatus.
- the obtained nonwoven fabric was placed on a mesh support, and ion-exchanged water having a pH of 6.7 and an electrical conductivity of 0.8 ⁇ S/cm was applied from a nozzle with a diameter of 0.1 mm ⁇ and a pitch of 0.6 mm positioned 2 cm above the support at a pressure of 1 MPa. It was ejected under pressure.
- the sheet was conveyed at a speed of 4 m/min while the pressure was kept under the mesh support just below the nozzle, and the front and back sides of the sheet were treated once each. Then, it was air-dried at 25° C. for 2 hours to form an electret.
- the initial collection efficiency was 99.997%
- the QF value was 1.79
- the performance maintenance rate was 0.90
- the a/b value was 0.04 in the depolarization current measurement by the TSC method
- the maximum peak temperature was 143°C.
- the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Example 2 Using the same raw materials and proportions as in Example 1, a melt-blowing apparatus was used to obtain a long-fiber nonwoven fabric having a basis weight of 18 g/m 2 and an average fiber diameter of 2.5 ⁇ m. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.992%, QF value 1.51, performance maintenance rate 0.88, a/b value 0.04 in depolarization current measurement by TSC method, maximum value of depolarization after 100 ° C. The peak temperature was 144°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Example 3 The same as Example 2 except that the concentration of zinc oxide particles (a) was 1% by mass using the masterbatch of (2) above, and a melt blowing apparatus was used to produce a basis weight of 18 g/m 2 and an average fiber diameter of 2.6 ⁇ m. A long fiber nonwoven fabric was obtained.
- electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.99%, QF value 1.53, performance retention rate 0.86, a/b value 0.06 in depolarization current measurement by TSC method, peak indicating maximum depolarization after 100 ° C The temperature was 143°C.
- the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Example 4 The same as Example 2 except that the concentration of the zinc oxide particles (a) was changed to 5% by mass using the masterbatch of ( 2 ) above. to obtain a long fiber nonwoven fabric.
- electretization was performed in the same manner as in Example 1.
- the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Example 5 The zinc oxide particles (a) had a particle diameter of 0.3 ⁇ m, and were added after preparation of a 10 % by mass masterbatch. A 6 ⁇ m long fiber nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.99%, QF value 1.48, performance maintenance rate 0.88, a/b value 0.04 in depolarization current measurement by TSC method, maximum value of depolarization after 100 ° C. The peak temperature was 140°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Example 1 A long-fiber nonwoven fabric having a basis weight of 18 g/m 2 and an average fiber diameter of 2.5 ⁇ m was obtained using a meltblowing apparatus in the same manner as in Example 2 except that the masterbatch of (3) was used.
- Initial collection efficiency 99.95%, QF value 1.25, performance retention rate at 100 ° C. 0.68, a / b value in depolarization current measurement by TSC method 1.01, maximum value of depolarization after 100 ° C. was a peak temperature of 130°C.
- the antibacterial activity value was 5 or more in terms of logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Comparative Example 2 The same as Comparative Example 1 except that the masterbatch of (3) above was used and the concentration of the zinc oxide particles ( b ) was 1% by mass. A fibrous nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.8%, QF value 1.03, performance retention rate at 100 ° C. 0.58, a / b value 1.87 in depolarization current measurement by TSC method, maximum depolarization after 100 ° C. The peak temperature indicating the value was 128°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
- Example 3 A long-fiber nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 2.5 ⁇ m was obtained using a meltblowing apparatus in the same manner as in Example 1 except that no zinc oxide particles were added. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.993%, QF value 1.53, performance maintenance rate 0.90, a/b value 0.03 in depolarization current measurement by TSC method, maximum depolarization after 100 ° C. The peak temperature was 144°C. In addition, the antibacterial activity value was 1 or less in logarithmic value for any bacterial species, and no effective antibacterial activity was obtained.
- the composition with a small a/b value has a high filter performance retention rate when charged with a liquid, and the use of zinc oxide particles with a small B/A value provides an excellent QF value.
- the a/b value which is a charge stability index, is small, and the filter performance retention rate is excellent even in the electret by liquid charging.
- the particle collection efficiency as a filter and the quality factor of the filter medium at the initial stage and after the heat load are both high, and they have excellent properties as an electret filter.
- it is compatible with the functionality of the zinc oxide particles.
Abstract
An electret according to the present invention contains zinc oxide particles in a polyolefin resin. When subjected to photoluminescence measurements, the zinc oxide particles exhibit a ratio (B/A) of the photoluminescence intensity A in the wavelength range of 350-400 nm and the photoluminescence intensity B in the wavelength range of 400-700 nm of 0.1 or lower.
Description
本発明はエレクトレット及びエレクトレットフィルターに関する。
The present invention relates to electrets and electret filters.
従来、防塵マスク、各種空調用エレメント、空気清浄機、キャビンフィルター、各種装置において集塵、保護、通気などを目的とした多孔質フィルターが用いられている。多孔質フィルターのうち、繊維状物からなるフィルターは高い空隙率を持ち、長寿命、低通気抵抗という利点を有している。このような繊維状物からなるフィルターとして、不織布が好適に用いられている。
Conventionally, dust masks, various air conditioning elements, air purifiers, cabin filters, and various devices have used porous filters for dust collection, protection, and ventilation. Among porous filters, filters made of fibrous materials have advantages of high porosity, long life and low airflow resistance. A nonwoven fabric is preferably used as a filter made of such a fibrous material.
さらに、上記のようなフィルターでは集塵等における捕集効率を向上させるため、エレクトレットの電気的な引力を利用する方法が知られている。エレクトレットとは各種誘電材料を種々操作することで、静電力の維持及び利用が可能な材料である。電荷を付与されエレクトレットとして形成されたフィルターは、エレクトレットフィルターとして幅広く用いられている。
Furthermore, in order to improve the efficiency of dust collection in filters such as those described above, there is a known method of utilizing the electrical attractive force of electrets. Electrets are materials capable of sustaining and utilizing electrostatic forces through various manipulations of various dielectric materials. Filters that are charged and formed as electrets are widely used as electret filters.
また近年、不織布に無機粒子が含有された機能性材料の検討がなされており、例えば、主成分の樹脂に界面活性剤と各種無機粒子とを混合して抗菌性不織布を得る技術が開示されている（例えば、特許文献１、２参照）。
In recent years, functional materials in which inorganic particles are contained in nonwoven fabrics have been studied. For example, a technique for obtaining antibacterial nonwoven fabrics by mixing surfactants and various inorganic particles with resin as the main component has been disclosed. (See Patent Documents 1 and 2, for example).
本発明者は機能性を有する無機粒子として酸化亜鉛に着目し、その機能性とエレクトレット特性との両立について検討を行ったところ、当初得られたエレクトレットは電荷安定性に劣るため、保管輸送時及びにおいて従来のエレクトレットとは同等の取り扱いができないという問題に直面した。
The inventor of the present invention focused on zinc oxide as an inorganic particle having functionality, and studied compatibility between its functionality and electret properties. However, we faced the problem that it could not be handled in the same way as the conventional electret.
そこで本発明は上記課題に鑑みなされ、その目的は、電荷安定性に優れた酸化亜鉛粒子含有のエレクトレット及びエレクトレットフィルターを提供することである。
Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide an electret and an electret filter containing zinc oxide particles with excellent charge stability.
本発明者らが鋭意検討した結果、特定の酸化亜鉛粒子を含有してなるエレクトレット及びエレクトレットフィルターとすることで、エレクトレット及び酸化亜鉛粒子の機能両立が可能であり優れた特性を有することを見出し本発明に到達した。発明を以下に示す。
As a result of intensive studies by the present inventors, it has been found that an electret and an electret filter containing specific zinc oxide particles can achieve both functions of the electret and zinc oxide particles and have excellent properties. arrived at the invention. The invention is shown below.
１．ポリオレフィン樹脂に酸化亜鉛粒子を含有したエレクトレットであり、前記酸化亜鉛粒子は、フォトルミネッセンス測定にて得られる波長３５０ｎｍ～４００ｎｍ領域におけるフォトルミネッセンス強度Ａと、波長４００ｎｍ～７００ｎｍ領域のフォトルミネッセンス強度Ｂとの比（Ｂ／Ａ）が０．１以下である、ことを特徴とするエレクトレット。
２．含窒素化合物を含有する、ことを特徴とする上記１に記載のエレクトレット。
３．ＴＳＣ法にて測定された５０から１００℃における脱分極電流の最大値をａ、１００℃以上における脱分極電流の最大値をｂとした場合に、ａ／ｂの値が０．３以下である、ことを特徴とする上記１または２に記載のエレクトレット。
４．長繊維不織布であるである、ことを特徴とする上記１から３のいずれか１に記載のエレクトレット。
５．液体接触法により荷電されてなる、ことを特徴とする上記１から４のいずれか１に記載のエレクトレット。
６．上記１から５のいずれかに記載のエレクトレットを用いた、ことを特徴とするエレクトレットフィルター。
７．濾材品質係数ＱＦ値が１．３ｍｍＡｑ-１以上であることを特徴とする上記６に記載のエレクトレットフィルター。 1. It is an electret containing zinc oxide particles in a polyolefin resin, and the zinc oxide particles have a photoluminescence intensity A in a wavelength range of 350 nm to 400 nm obtained by photoluminescence measurement, and a photoluminescence intensity B in a wavelength range of 400 nm to 700 nm. An electret characterized by having a ratio (B/A) of 0.1 or less.
2. 2. The electret as described in 1 above, which contains a nitrogen-containing compound.
3. The value of a/b is 0.3 or less, where a is the maximum value of the depolarization current at 50 to 100°C measured by the TSC method, and b is the maximum value of the depolarization current at 100°C or higher. 3. The electret according to 1 or 2 above, characterized in that:
4. 4. The electret according to any one of 1 to 3 above, which is a long-fiber nonwoven fabric.
5. 5. The electret according to any one of 1 to 4 above, which is charged by a liquid contact method.
6. 6. An electret filter using the electret according to any one of 1 to 5 above.
7. 7. The electret filter as described in 6 above, wherein the filter medium quality factor QF value is 1.3 mmAq -1 or more.
２．含窒素化合物を含有する、ことを特徴とする上記１に記載のエレクトレット。
３．ＴＳＣ法にて測定された５０から１００℃における脱分極電流の最大値をａ、１００℃以上における脱分極電流の最大値をｂとした場合に、ａ／ｂの値が０．３以下である、ことを特徴とする上記１または２に記載のエレクトレット。
４．長繊維不織布であるである、ことを特徴とする上記１から３のいずれか１に記載のエレクトレット。
５．液体接触法により荷電されてなる、ことを特徴とする上記１から４のいずれか１に記載のエレクトレット。
６．上記１から５のいずれかに記載のエレクトレットを用いた、ことを特徴とするエレクトレットフィルター。
７．濾材品質係数ＱＦ値が１．３ｍｍＡｑ-１以上であることを特徴とする上記６に記載のエレクトレットフィルター。 1. It is an electret containing zinc oxide particles in a polyolefin resin, and the zinc oxide particles have a photoluminescence intensity A in a wavelength range of 350 nm to 400 nm obtained by photoluminescence measurement, and a photoluminescence intensity B in a wavelength range of 400 nm to 700 nm. An electret characterized by having a ratio (B/A) of 0.1 or less.
2. 2. The electret as described in 1 above, which contains a nitrogen-containing compound.
3. The value of a/b is 0.3 or less, where a is the maximum value of the depolarization current at 50 to 100°C measured by the TSC method, and b is the maximum value of the depolarization current at 100°C or higher. 3. The electret according to 1 or 2 above, characterized in that:
4. 4. The electret according to any one of 1 to 3 above, which is a long-fiber nonwoven fabric.
5. 5. The electret according to any one of 1 to 4 above, which is charged by a liquid contact method.
6. 6. An electret filter using the electret according to any one of 1 to 5 above.
7. 7. The electret filter as described in 6 above, wherein the filter medium quality factor QF value is 1.3 mmAq -1 or more.
本発明により、電荷安定性及び酸化亜鉛粒子による機能性を両方有する優れたエレクトレット及びフィルターを得ることができる。
According to the present invention, excellent electrets and filters having both charge stability and zinc oxide particle functionality can be obtained.
以下、本発明に関して具体的に説明するが、本発明は下記に限定される訳ではなく前・後記の趣旨に適合し得る範囲で適当に変更を加えて実施することも可能であり、それらはいずれも本発明の技術的範囲に包含される。
Hereinafter, the present invention will be specifically described, but the present invention is not limited to the following, and can be implemented with appropriate modifications within the scope that can conform to the gist of the preceding and following descriptions. All are included in the technical scope of the present invention.
本発明のエレクトレットは、形状の自由度及びエレクトレットの電荷安定性の観点から、疎水性かつ電気抵抗の高いポリオレフィン樹脂を用いる。ポリオレフィン樹脂としては、例えば、エチレン、プロピレン、ブチレン、ヘキセン、オクテン、ブタジエン、イソプレン、クロロプレン、メチル－１－ペンテン、環状オレフィンなどのオレフィンの単独重合体や２種類以上の上記オレフィン及びハロゲン化オレフィンからなる共重合体が挙げられる。ポリオレフィン樹脂は１種を選択して単独で使用してもよいし、２種以上を選択して組み合わせて使用してもよい。ポリオレフィン樹脂は、ポリエチレン、ポリプロピレン及びポリメチルペンテンから選ばれる少なくとも１種が含まれることが好ましく、ポリプロピレンを含むことがより好ましい。エレクトレット１００質量％中におけるポリオレフィン樹脂の含有割合が８０質量％以上であることが好ましく、８５質量％以上であることがより好ましく、９０質量％以上であることがさらに好ましく、９５質量％以上であることが特に好ましく、９７質量％以上であることが最も好ましい。
The electret of the present invention uses a polyolefin resin that is hydrophobic and has high electrical resistance, from the viewpoint of the degree of freedom of shape and the electret's charge stability. Examples of polyolefin resins include homopolymers of olefins such as ethylene, propylene, butylene, hexene, octene, butadiene, isoprene, chloroprene, methyl-1-pentene, and cyclic olefins, and two or more of the above olefins and halogenated olefins. A copolymer such as One type of polyolefin resin may be selected and used alone, or two or more types may be selected and used in combination. The polyolefin resin preferably contains at least one selected from polyethylene, polypropylene and polymethylpentene, and more preferably contains polypropylene. The content of the polyolefin resin in 100% by mass of the electret is preferably 80% by mass or more, more preferably 85% by mass or more, still more preferably 90% by mass or more, and 95% by mass or more. is particularly preferable, and 97% by mass or more is most preferable.
本発明に用いられる樹脂においては、立体規則性度が８５％以上であることが好ましく、より好ましくは９０％以上であり、更に好ましくは９０％以上であり、最も好ましくは９５％以上である。この場合、アイソタクチック、シンジオタクチックいずれでも好ましく用いることができる。２種以上のポリプロピレンを用いる場合には、含有されるポリオレフィン中に１種以上含まれることが好ましい。
The resin used in the present invention preferably has a stereoregularity of 85% or more, more preferably 90% or more, still more preferably 90% or more, and most preferably 95% or more. In this case, either isotactic or syndiotactic can be preferably used. When two or more types of polypropylene are used, it is preferable that one or more types are contained in the contained polyolefin.
本発明に用いられるポリオレフィン樹脂においては、各種分子量分布ならびに粘度特性を有するものを好ましく用いることが可能であり、必要とされる最終形状及び加工性に応じて分岐鎖構造などを選択することもできる。この場合においても１種もしくは２種以上組み合わせて用いる事も好ましい。
In the polyolefin resin used in the present invention, those having various molecular weight distributions and viscosity characteristics can be preferably used, and the branched chain structure and the like can be selected according to the required final shape and workability. . Also in this case, it is preferable to use one or a combination of two or more.
本発明におけるエレクトレットは、ポリオレフィン樹脂中に、酸化亜鉛粒子を含有することを特徴とする。所望の特性を有する酸化亜鉛粒子であれば、必要特性に応じて１種もしくは２種類以上組み合わせて用いることも好ましい。酸化亜鉛粒子の具体的な機能としては誘電性、不透明性、着色性、抗菌性、抗カビ性、臭気除去特性、抗ウイルス性、抗アレルゲン性などを例示することができる。
The electret in the present invention is characterized by containing zinc oxide particles in polyolefin resin. As long as the zinc oxide particles have the desired properties, it is also preferable to use one or a combination of two or more of them depending on the required properties. Specific functions of zinc oxide particles include dielectric properties, opacity, coloring properties, antibacterial properties, antifungal properties, odor removing properties, antiviral properties, and antiallergenic properties.
本発明に用いられる酸化亜鉛粒子の形状としては、板状、針状、矩形、球形、楕円形などいずれの形状であってもよい。これらは、単結晶及び多結晶からなる一次粒子、強い結合もしくは弱い結合による二次粒子であってもよい。エレクトレットの電荷安定性を向上させる目的においては、アスペクト比の小さな球形もしくは矩形、板状であることが好ましく、下記の粒子サイズからなる単結晶及び多結晶からなる一次粒子、もしくは強い結合からなる二次粒子であることが好ましく、最も好ましくは一次粒子が下記の大きさであることがより好ましい。押出、混合加工時に意図しない細粒化が抑制されるとともに表面積を小さくすることが可能であるため、エレクトレット特性の維持に好ましい組成物が得られる。
The shape of the zinc oxide particles used in the present invention may be plate-like, needle-like, rectangular, spherical, elliptical, or any other shape. These may be monocrystalline and polycrystalline primary particles, secondary particles with strong or weak bonds. For the purpose of improving the charge stability of the electret, it is preferably spherical, rectangular, or tabular with a small aspect ratio. It is preferred that the particles are primary particles, and most preferably the primary particles have the following sizes. Unintended grain refinement is suppressed during extrusion and mixing processing, and the surface area can be reduced, so that a composition preferable for maintaining electret properties can be obtained.
本発明に用いられる酸化亜鉛粒子の平均粒子径は、０．１μｍから１０μｍの大きさである。好ましくは０．１μｍ～８μｍであり、より好ましくは０．１～５μｍであり、更に好ましくは０．１～３μｍであり、最も好ましくは０．１～２μｍである。粒子径が小さい場合にはナノ粒子として取り扱い上の懸念があり、各種ナノ物質規制への対応において重要な特性である。その一方で、大きすぎる場合には分散性が悪くなるとともに機能性発現のために多量に添加する必要がある。また、酸化亜鉛粒子が含まれるポリオレフィン樹脂の脆化及び加工性低下が生じやすい。
The average particle size of the zinc oxide particles used in the present invention ranges from 0.1 μm to 10 μm. It is preferably 0.1 μm to 8 μm, more preferably 0.1 to 5 μm, even more preferably 0.1 to 3 μm, most preferably 0.1 to 2 μm. If the particle size is small, there is concern about handling as nanoparticles, which is an important characteristic in dealing with various nano-substance regulations. On the other hand, if it is too large, the dispersibility becomes poor and it is necessary to add a large amount in order to develop the functionality. In addition, the polyolefin resin containing zinc oxide particles tends to become brittle and deteriorate in workability.
酸化亜鉛粒子の添加量に関しては、必要な機能性に応じて好ましく調整することができるが、例えば抗菌効果としては、ポリオレフィン樹脂組成物として０．０３～１０質量％含まれることが好ましく、より好ましくは０．０５～７質量％であり、更に好ましくは０．１～５質量％であり、最も好ましくは０．１５～３質量％である。少なすぎる場合には抗菌効果が不十分であり、多すぎる場合には加工性低下及び機械的強度が低下する。
The amount of zinc oxide particles to be added can be preferably adjusted according to the required functionality. is 0.05 to 7% by mass, more preferably 0.1 to 5% by mass, most preferably 0.15 to 3% by mass. If it is too small, the antibacterial effect will be insufficient, and if it is too large, workability and mechanical strength will be lowered.
本発明に用いられる酸化亜鉛粒子は、フォトルミネッセンス（ＰＬ）測定において特定の特性を有することで、エレクトレット特性と酸化亜鉛粒子の添加による機能性とを両立することが特徴である。具体的には、波長３２５ｎｍのレーザー光で励起し、フォトルミネッセンスとして得られる発光をＣＣＤ検出器にて波長３５０から７００ｎｍの範囲で検出する。本発明に用いられる酸化亜鉛粒子では、このフォトルミネッセンス測定を行った場合に、波長３５０ｎｍ～４００ｎｍ領域のフォトルミネッセンス強度Ａと、波長５００ｎｍ～７００ｎｍ領域のフォトルミネッセンス強度Ｂとの比（Ｂ／Ａ）が０．１以下である。Ｂ／Ａは、０．０９以下であることが好ましく、より好ましくは０．０５以下であり、更に好ましくは０．０２５以下であり、最も好ましくは０．０１以下である。
The zinc oxide particles used in the present invention are characterized by having specific characteristics in photoluminescence (PL) measurement, thereby achieving both electret characteristics and functionality due to the addition of zinc oxide particles. Specifically, it is excited by laser light with a wavelength of 325 nm, and luminescence obtained as photoluminescence is detected with a CCD detector in a wavelength range of 350 to 700 nm. In the zinc oxide particles used in the present invention, when this photoluminescence measurement is performed, the ratio (B/A) of the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm and the photoluminescence intensity B in the wavelength range of 500 nm to 700 nm. is 0.1 or less. B/A is preferably 0.09 or less, more preferably 0.05 or less, still more preferably 0.025 or less, and most preferably 0.01 or less.
ここで、強度とはＣＣＤの検出感度を波長毎の検出感度で補正を行ったものであり、波長ごとの光子量として相対比較可能とするものである。また、上記各々の範囲における最大高さをＡ及びＢの値として用いる。ピークとして存在する場合にはピーク値、裾野として存在する場合にはピーク境界側に存在する最大値を意味する。あくまで連続的に生じるフォトルミネッセンスのスペクトルと解釈されるものであり、スパイク状の大ノイズ及び計測異常値とは明確に区別される。
Here, the intensity is obtained by correcting the detection sensitivity of the CCD with the detection sensitivity for each wavelength, and allows relative comparison as the amount of photons for each wavelength. Also, the maximum height in each of the above ranges is used as the value of A and B. When it exists as a peak, it means the peak value, and when it exists as a tail, it means the maximum value existing on the peak boundary side. It is interpreted as a spectrum of continuously occurring photoluminescence, and is clearly distinguished from large spike-like noise and measurement abnormal values.
本発明者の検討によると、Ｂ／Ａ値が小さいほどエレクトレットの電荷安定性に寄与し、またエレクトレットを液体荷電法によるエレクトレットフィルターとして用いた場合に初期性能にも優れることが見いだされた。メカニズムは明確ではないが、Ｂ／Ａ値が、酸化亜鉛粒子自身もしくはエレクトレットとなる樹脂組成物における電気抵抗率、エレクトレットの酸化、光化学反応などのメカニズムにより、電荷安定性及びエレクトレット特性に影響するものと考えられる。
According to the study of the present inventor, it was found that the smaller the B/A value, the better the charge stability of the electret, and the better the initial performance when the electret is used as an electret filter by the liquid charging method. Although the mechanism is not clear, the B/A value affects charge stability and electret properties due to mechanisms such as the electrical resistivity of the zinc oxide particles themselves or the resin composition that becomes the electret, the oxidation of the electret, and the photochemical reaction. it is conceivable that.
上記のフォトルミネッセンス測定においては、酸化亜鉛粒子単体、樹脂中に酸化亜鉛粒子を高濃度分散させたマスターバッチ又はコンパウンドにおける酸化亜鉛粒子、エレクトレット表面に存在する酸化亜鉛粒子など測定可能な状態であれば計測することが可能である。ポリオレフィン樹脂と酸化亜鉛粒子の混合物から焼成又は薬剤による溶解により取り出すことで測定感度を補うことも可能である、本発明においては、酸化亜鉛粒子単体、樹脂マスターバッチ又はコンパウンド、エレクトレットいずれかで上記の数値を満たせばよく、より好ましくは全ての状態で満たすことである。
In the above photoluminescence measurement, zinc oxide particles alone, zinc oxide particles in a masterbatch or compound in which zinc oxide particles are dispersed in a resin at a high concentration, zinc oxide particles present on the surface of the electret, etc. It is possible to measure It is also possible to supplement the measurement sensitivity by taking out from a mixture of polyolefin resin and zinc oxide particles by baking or dissolving with a chemical. It suffices if the numerical values are satisfied, and more preferably it is satisfied in all states.
フォトルミネッセンスの測定機としては、検出感度ならびにベースラインのノイズ値が低く安定していることが必要であり、ノイズ値とフォトルミネッセンスにより得られる測定値は厳密に異なるものである。この場合は光源強度ならびに検出器、試料の調整を行うことで、波長３５０～４００ｎｍ及び５００～７００ｎｍにおけるフォトルミネッセンス強度比を本発明の範囲で検出することが必要である。すなわち、波長３５０～４００ｎｍにおける検出強度に対して５００～７００ｎｍのノイズは十分に小さく、十分な感度特性を有するものを用いる。また、点在する酸化亜鉛を計測する場合には、微細領域での計測が可能な顕微式であることがより好ましい。
As a photoluminescence measuring instrument, it is necessary that the detection sensitivity and baseline noise value are low and stable, and the noise value and the measured value obtained by photoluminescence are strictly different. In this case, it is necessary to detect the photoluminescence intensity ratio at wavelengths of 350 to 400 nm and 500 to 700 nm within the scope of the present invention by adjusting the light source intensity, detector, and sample. That is, the noise at 500 to 700 nm is sufficiently small with respect to the detection intensity at a wavelength of 350 to 400 nm, and the one having sufficient sensitivity characteristics is used. Further, when measuring scattered zinc oxide, it is more preferable to use a microscopic system capable of measuring in a minute area.
本発明において用いられるポリオレフィン樹脂への酸化亜鉛粒子の添加方法は、所望の特性が得られるものであれば特に制限されないが、樹脂重合時に酸化亜鉛粒子もしくは前駆体を添加する方法、マスターバッチ又はコンパウンド製造時に酸化亜鉛粒子もしくは前駆体を添加する方法、成形時に酸化亜鉛粒子もしくは前駆体を添加する方法、成形されたポリオレフィン表面に対し溶融付着させる方法などを例示することができ、単独もしくは組み合わせて用いることができる。
The method of adding zinc oxide particles to the polyolefin resin used in the present invention is not particularly limited as long as the desired properties can be obtained. Examples include a method of adding zinc oxide particles or precursors during production, a method of adding zinc oxide particles or precursors during molding, and a method of melting and adhering to the surface of molded polyolefin, which are used alone or in combination. be able to.
このうち、予め所定の特性を有する酸化亜鉛粒子を、マスターバッチ又はコンパウンド製造時に樹脂に添加する方法、もしくは、繊維状物、フィルム、押出材などの成形体の製造時に押出機内に樹脂とともに添加し、溶融混合する方法が好ましく用いられる。
Among these methods, zinc oxide particles having predetermined properties are added in advance to the resin during masterbatch or compound production, or they are added together with the resin into the extruder during the production of molded articles such as fibrous materials, films, and extruded materials. , a method of melt-mixing is preferably used.
マスターバッチ又はコンパウンドの製造においては、各種溶融混練機ならびに、一軸もしくは二軸以上の多軸押出機をもちいることが可能であり、ミキシング部分を特に強化したスクリュー形状であることも好ましい。樹脂と酸化亜鉛粒子の混合は予めタンブラー又は各種ミキサーにて混合してもよいし、フィーダーにて別供給とすることも装置の特性に応じて好ましく選択することができる。投入口に関しては樹脂と酸化亜鉛粒子同時でもよいし、溶融樹脂内への酸化亜鉛粒子の途中混合であってもよい。
In the production of the masterbatch or compound, it is possible to use various melt kneaders and multi-screw extruders with one or more than two screws, and it is also preferable to use a screw shape with a particularly strengthened mixing portion. The resin and zinc oxide particles may be mixed in advance using a tumbler or various mixers, or may be separately supplied using a feeder, which can be preferably selected according to the characteristics of the apparatus. Regarding the inlet, the resin and the zinc oxide particles may be introduced simultaneously, or the zinc oxide particles may be mixed into the molten resin in the middle.
本発明においては、溶融混合時及び成形時の酸化亜鉛粒子の分散性を向上させるために、分散剤を用いることができる。分散性とエレクトレット性及び酸化亜鉛粒子の機能性発現に好適な材料であれば特に制限されないが、酸化亜鉛粒子に親和性を有する、エステル基、カルボキシル基、スルホン酸基、アミド基、アミノ基、エーテル基等の親水性基、及び炭化水素基、ペルフルオロ基などの疎水性基を単一分子内に有するものを好ましく用いることが出来る。分子量に関しては、粘度及び対象とする酸化亜鉛粒子の大きさ及び分散性を考慮し、適切なものを用いることができる。また、実質的に界面活性剤と同一の化学物質であってもよい。分散剤に関しては予め酸化亜鉛粒子に付着させることも、混合時に添加することも好ましい。
In the present invention, a dispersant can be used to improve the dispersibility of the zinc oxide particles during melt mixing and molding. The material is not particularly limited as long as it is suitable for exhibiting dispersibility, electret properties, and functionality of zinc oxide particles. Those having a hydrophilic group such as an ether group and a hydrophobic group such as a hydrocarbon group and a perfluoro group in a single molecule can be preferably used. As for the molecular weight, an appropriate one can be used, taking into account the viscosity and the size and dispersibility of the zinc oxide particles of interest. It may also be substantially the same chemical substance as the surfactant. Regarding the dispersant, it is preferable to attach it to the zinc oxide particles in advance or to add it during mixing.
分散剤が例えばエステル基を含む化合物である場合、グリセリン脂肪酸エステル類、ソルビタン脂肪酸エステル類、脂肪酸エステル類などを一例として例示することが可能であり、酸化亜鉛粒子及びポリオレフィンとの親和性及び融点を勘案して用いることができる。
For example, when the dispersant is a compound containing an ester group, glycerin fatty acid esters, sorbitan fatty acid esters, fatty acid esters, etc. can be exemplified, and the affinity and melting point of the zinc oxide particles and polyolefin can be improved. It can be used with consideration.
溶融時に混合される分散剤の融点としては押出機での溶融及び分散機能を勘案して、エレクトレットとなるポリオレフィン樹脂よりも融点が同一もしくは低いものが好ましく、より好ましくは２０℃以上低いものであり、更に好ましくは５０℃以上である。
The melting point of the dispersant mixed during melting is preferably the same or lower than that of the electret polyolefin resin, more preferably 20° C. or more, in consideration of the melting and dispersing functions in the extruder. , and more preferably 50°C or higher.
分散剤が、酸化亜鉛粒子との反応性が著しく高い、及び／又は融点がエレクトレットの主成分のポリオレフィン樹脂よりも高い場合には、溶液もしくは前駆体の状態で塗布もしくは加熱混合を用い、予め酸化亜鉛粒子表面に付着させておくことも好ましい。
When the dispersant has a significantly high reactivity with the zinc oxide particles and/or has a higher melting point than the polyolefin resin which is the main component of the electret, it is pre-oxidized using coating or heat mixing in a solution or precursor state. It is also preferable to attach it to the zinc particle surface.
また、酸化亜鉛粒子の表面を有機もしくは無機材料にて表面処理及びドーピング処理しておくことも好ましく、各種のシランカップリング剤、有機酸、含窒素有機化合物、無機元素及び無機酸化物を用いることができる。上記の方法において、酸化亜鉛粒子の保存性や分散性、光学活性、誘電性、抗菌、抗菌、抗ウイルス、抗アレルゲン性、導電性、溶解性、親水性及び疎水性を調整することも好ましい。酸化亜鉛粒子表面にのみ機能性官能基をとどめておくことで、エレクトレット特性に影響を与えない機能性付与も可能となる。
It is also preferable to surface-treat and dope the surface of the zinc oxide particles with an organic or inorganic material, and various silane coupling agents, organic acids, nitrogen-containing organic compounds, inorganic elements and inorganic oxides can be used. can be done. In the above method, it is also preferred to adjust the preservability, dispersibility, optical activity, dielectric properties, antibacterial, antibacterial, antiviral, antiallergenic properties, electrical conductivity, solubility, hydrophilicity and hydrophobicity of the zinc oxide particles. By leaving functional functional groups only on the surface of zinc oxide particles, it is possible to impart functionality without affecting the electret properties.
また、酸化亜鉛粒子を混合するマスターバッチ又はコンパウンドを製造するための基材となる樹脂素材も必要に応じて分子構造、粘度及び流動特性を調整することができる。例えば一例として、酸化亜鉛粒子との親和性及び濡れ性の調節、エレクトレット及び最終形態となる被添加側の樹脂粘度の調節、酸化亜鉛粒子の分散、表面析出及び固定状態の調節、相分離構造の調節、酸化亜鉛粒子の偏在及び他種機能を発現させる目的などを例示することができる。これらはポリオレフィン樹脂に限定されず用いることができる。
In addition, the molecular structure, viscosity, and flow characteristics of the resin material that serves as the base material for manufacturing the masterbatch or compound that mixes the zinc oxide particles can be adjusted as necessary. For example, as an example, adjustment of affinity and wettability with zinc oxide particles, adjustment of electret and resin viscosity on the side to be added which is the final form, dispersion of zinc oxide particles, adjustment of surface precipitation and fixed state, phase separation structure Examples include the purpose of regulation, the uneven distribution of zinc oxide particles, and the expression of other types of functions. These can be used without being limited to polyolefin resins.
また、本発明においては上記マスターバッチ又はコンパウンドに各種の機能材を同時に混合しておくことも好ましく、例えば後述するエレクトレット性を向上させるための含窒素化合物、各種酸化防止剤、耐熱性向上剤、粘度及び結晶性調整剤、顔料、滑剤、付着防止剤などを例示することができる。酸化亜鉛粒子の分散剤と上記機能材とを同一とすることも好ましい。
Further, in the present invention, it is also preferable to mix various functional materials in the masterbatch or compound at the same time. For example, nitrogen-containing compounds, various antioxidants, heat resistance improvers, and Viscosity and crystallinity modifiers, pigments, lubricants, antiadhesives and the like can be exemplified. It is also preferable to use the same dispersant for the zinc oxide particles and the functional material.
本発明は、酸化亜鉛粒子を含有したポリオレフィン樹脂から成るエレクトレットである。エレクトレット化は従来公知の方法を用いることが可能であり、例えば、常温もしくは昇温状態にて電界分極させる方法、電極と接触させ通電させることで正負の電荷を与える方法、光もしくは放射線等による光電効果を利用し電荷を与える方法、液体や固体の接触もしくは摩擦により電荷を与える方法、破砕や分割により電荷を与える方法、荷電粒子もしくは荷電イオンの衝突により電荷を与える方法、屈曲や相変化等などを利用し電荷を与える方法などを例示することができる。このうち、被荷電体が繊維状物からなる場合には、水又は水を含む液体との接触によりエレクトレット化する液体接触法が好適である。また、帯電増強剤として含窒素化合物を添加することで効果的に電荷を付与することが可能となる。
The present invention is an electret made of polyolefin resin containing zinc oxide particles. Conventionally known methods can be used for electretization, for example, a method of electric field polarization at room temperature or at an elevated temperature, a method of giving positive and negative charges by contacting with electrodes and energizing, photoelectric conversion by light or radiation, etc. Methods of imparting electric charge using effects, methods of imparting electric charge by contact or friction of liquids or solids, methods of imparting electric charge by crushing or splitting, methods of imparting electric charge by collision of charged particles or charged ions, bending, phase change, etc. can be exemplified. Among these methods, when the material to be charged is made of a fibrous material, the liquid contact method, in which the material is electretized by contact with water or a liquid containing water, is preferable. Further, by adding a nitrogen-containing compound as an electrification enhancer, it becomes possible to effectively impart an electric charge.
液体接触法としては効果的にエレクトレット化できるものであれば特に制限されないが、被荷電体が例えば不織布などの繊維状物である場合は、吸引及び／又は加圧により、繊維状物の層内を厚さ方向に液体を接触及び通過させたのち、除去、乾燥させる方法が好ましく用いられる。液体を接触及び通過させる方法としては、所望の効果が得られるものであれば特に制限されないが、噴射、圧入、凝縮、吸引などの方法を用いることが可能であり、除去及び乾燥方法としては、吸引もしくは雰囲気の減圧、熱及び電磁波などを利用した加熱などを用いることができる。噴射と減圧及び乾燥の組合せが連続的な処理工程として好ましい。
The liquid contact method is not particularly limited as long as it can be effectively electretized. A method of contacting and passing a liquid in the thickness direction, then removing and drying is preferably used. The method of contacting and passing the liquid is not particularly limited as long as the desired effect can be obtained, but methods such as injection, injection, condensation, and suction can be used. Heating using suction, atmospheric pressure reduction, heat, electromagnetic waves, or the like can be used. A combination of spraying, vacuum and drying is preferred as a continuous process step.
液体接触法の各処理について具体例を次に示す。被荷電体が例えば不織布などの繊維状物である場合、繊維状物を通気度５０～４００ｃｍ３／ｃｍ２／秒の網状支持体に載せ、この上方より水を噴射する。通気度はＪＩＳ Ｌ１０９６に記載のフランジール形試験機を用いて測定できる。
Concrete examples of each treatment of the liquid contact method are shown below. When the material to be charged is a fibrous material such as non-woven fabric, the fibrous material is placed on a mesh support having an air permeability of 50 to 400 cm 3 /cm 2 /sec, and water is sprayed from above. The air permeability can be measured using a frandil type tester described in JIS L1096.
上記網状支持体とは、具体的には金属ヤーンやプラスチックヤーンの織物からなる多孔構造物であり、平織り、綾織り、朱子織りなどの織り形状が挙げられる。金属素材としてはステンレス、ブロンズ等、またプラスチック素材としてはポリプロピレン、ポリエステル、ポリウレタン、ナイロン、ポリフェニレンサルファイドなどが挙げられる。
The above-mentioned net-like support is specifically a porous structure made of a fabric of metal yarn or plastic yarn, and includes woven shapes such as plain weave, twill weave, and satin weave. Examples of metal materials include stainless steel and bronze, and examples of plastic materials include polypropylene, polyester, polyurethane, nylon, and polyphenylene sulfide.
例えば、水噴射は被荷電体の数ｃｍ上方に設置されたノズルより、洗浄及び厚さ方向に通水するのに十分な圧力で噴射する。十分な圧力は、特に定めないが、ノズルの孔形状及び被荷電体の目付や製造法によって異なる。被荷電体である繊維状物が例えば、目付が５～５０ｇ／ｍ２のポリオレフィンメルトブロー不織布の場合には、０．３～３ＭＰａ、５０～２００ｇ／ｍ２のポリオレフィンメルトブロー不織布に対しては、１～４ＭＰａであることが好ましい。噴射の圧力が高すぎると、ピンホールや破断が生じる。また圧力が低すぎると十分に水が通過することができずエレクトレット化が不十分となる。
For example, water is jetted from a nozzle placed several cm above the object to be charged at a pressure sufficient to wash and pass the water in the thickness direction. Sufficient pressure is not specified, but varies depending on the shape of the nozzle hole, the basis weight of the charged body, and the manufacturing method. When the fibrous material to be charged is, for example, a polyolefin melt-blown nonwoven fabric with a basis weight of 5 to 50 g/m 2 , 0.3 to 3 MPa, for a polyolefin melt blown nonwoven fabric of 50 to 200 g/m 2 , It is preferably ~4 MPa. If the injection pressure is too high, pinholes and breaks will occur. On the other hand, if the pressure is too low, sufficient water cannot pass through, resulting in insufficient electretization.
ノズルは直径０．０５～０．２ｍｍの孔を、０．５～３ｍｍピッチで１列あるいは複数列配置したものが例示される。また、例えば網状支持体を可動とし、繊維状物を長手方向に搬送させることにより噴射処理を連続的に行うことができるものが好ましい。搬送速度は特に限定されないが、好ましい範囲を挙げると、１～１００ｍ／分である。また最適な噴射回数や処理面（片面か両面か）は繊維状物の目付や平均繊維径に依存するため、特に限定されない。
An example of the nozzle is one in which holes with a diameter of 0.05 to 0.2 mm are arranged in one or more rows at a pitch of 0.5 to 3 mm. Further, it is preferable that the net-like support is movable and the fibrous material can be conveyed in the longitudinal direction so that the jetting treatment can be continuously performed. The conveying speed is not particularly limited, but a preferable range is 1 to 100 m/min. Also, the optimum number of injections and the treatment surface (one side or both sides) are not particularly limited because they depend on the basis weight and average fiber diameter of the fibrous material.
また、水噴射と同時に、網状支持体の下方を、真空ポンプ又は排気ブロアー等を用いて減圧状態とすることが好ましい。吸引時の負圧は特に限定されないが、例えば、－０．０１～－０．５ｋＰａが好適である。減圧状態にすると、繊維状物内を効果的に水が通過し、かつ保水量を減らすことができる。
In addition, it is preferable to reduce the pressure below the mesh support by using a vacuum pump, an exhaust blower, or the like, at the same time as the water is sprayed. The negative pressure during suction is not particularly limited, but is preferably -0.01 to -0.5 kPa, for example. When the pressure is reduced, water can effectively pass through the fibrous material and the amount of retained water can be reduced.
水噴射処理後の乾燥方法については、熱風乾燥法、真空乾燥法、自然乾燥法等の方法が適用可能である。これらのうち熱風乾燥法は、連続処理が可能であるため好ましい。熱風乾燥法の場合、繊維の溶融及びフィルム化を生じない程度の温度にする必要がある。好ましくは１４０℃以下、より好ましくは１２０℃以下、さらに好ましくは１００℃以下とするのがよい。また、熱風乾燥前に、予備乾燥として、吸水ロール、サクション吸引等によって過剰な水分を取り除いておくことがより好ましい。本発明のエレクトレットは電荷安定性に優れるため、加熱乾燥工程を経た後も高い電荷量を保持することができる。
As for the drying method after water injection treatment, methods such as hot air drying, vacuum drying, and natural drying can be applied. Among these, the hot air drying method is preferable because continuous treatment is possible. In the case of the hot air drying method, the temperature must be such that the fibers do not melt or form a film. It is preferably 140° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower. In addition, it is more preferable to remove excess water by using a water absorbing roll, suction suction, or the like as preliminary drying before hot-air drying. Since the electret of the present invention has excellent charge stability, it can retain a large amount of charge even after being subjected to a heat drying step.
本発明において、液体接触法に用いる好ましい水については、効果的にエレクトレット化できるものであれば特に制限されないが、無機塩及び高沸点有機物が少ないことが好ましく、イオン交換樹脂、逆浸透膜などを使用し、高度に浄化されたものを用いことが特に好ましい。ｐＨに関しても酸化亜鉛粒子ならびに帯電増強剤の有無及び性質による合せにより、溶解性、帯電極性、帯電量などを勘案して設定できる。一般的にはｐＨの範囲として１～１２、より好ましくは２～１１、更に好ましくは３～１０、最も好ましくは４～９の範囲である。
In the present invention, the water preferably used in the liquid contact method is not particularly limited as long as it can be effectively electretized, but it is preferably less inorganic salts and high boiling point organic substances, and ion exchange resins, reverse osmosis membranes, etc. It is particularly preferable to use one that has been used and highly purified. The pH can also be set in consideration of the solubility, charge polarity, amount of charge, etc., depending on the presence and properties of the zinc oxide particles and charge enhancer. Generally, the range of pH is 1-12, more preferably 2-11, still more preferably 3-10, and most preferably 4-9.
本発明においては、帯電増強剤として含窒素化合物を添加することで液体接触法によるエレクトレット化を効果的とすることができる。エレクトレットとなるポリオレフィン樹脂組成物中に占める含窒素化合物の含有割合は０．１～５質量％であることが好ましく、０．５～３質量％であることが更に好ましく、０．７５～１．５質量％であることが最も好ましい。なお、エレクトレットにおいて２種類以上の繊維を混ぜている場合や一つの繊維に２種類以上の樹脂を混ぜている場合にはポリオレフィン樹脂に含まれている含窒素化合物の割合のことを指す。エレクトレット中にポリオレフィン以外の樹脂が含まれている場合であっても、ポリオレフィン以外の樹脂は溶媒・酸塩基に溶解したり、染色性が異なるため、判別可能であり、ＤＳＣやＮＭＲなどの定量法でもポリオレフィン樹脂を判別可能である。含窒素化合物の含有割合が０．１質量％より低い場合には電荷量が低くなるため濾過特性が低下してしまい、５質量％より高い場合には親水性増大によりエレクトレットとしての安定性が失われる。
In the present invention, by adding a nitrogen-containing compound as an electrification enhancer, electretization by a liquid contact method can be made effective. The content of the nitrogen-containing compound in the electret polyolefin resin composition is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass, and more preferably 0.75 to 1.5% by mass. 5% by weight is most preferred. When two or more types of fibers are mixed in the electret, or when two or more types of resin are mixed in one fiber, it refers to the ratio of the nitrogen-containing compound contained in the polyolefin resin. Even if the electret contains a resin other than polyolefin, it can be distinguished because the resin other than polyolefin dissolves in solvents and acid bases and has different dyeability, and quantitative methods such as DSC and NMR Even polyolefin resin can be distinguished. If the content of the nitrogen-containing compound is less than 0.1% by mass, the amount of charge is low, resulting in deterioration in filtration characteristics. will be
含窒素化合物は所望の帯電及び加工、混合特性が得られるものであれば特に制限されないが、２，２，６，６－テトラメチルピペリジンの構造及びトリアジン構造の少なくとも一方を含むヒンダードアミン化合物であることが好ましく、ヒンダードアミン化合物は２，２，６，６－テトラメチルピペリジンの構造及びトリアジン構造の両者を含むことがより好ましい。ピペリジン構造内に有する第二級窒素においては、Ｎ－Ｈ、ＮＯＲ、Ｎ－Ｒなどいずれの様態であっても好ましく用いることできる。
The nitrogen-containing compound is not particularly limited as long as desired charging, processing, and mixing properties can be obtained, but it should be a hindered amine compound containing at least one of a 2,2,6,6-tetramethylpiperidine structure and a triazine structure. is preferred, and the hindered amine compound more preferably contains both a 2,2,6,6-tetramethylpiperidine structure and a triazine structure. The secondary nitrogen in the piperidine structure can be preferably used in any form such as NH, NOR, and NR.
ヒンダードアミン化合物としては、特に限定するわけではないが、例えば、ポリ［｛６－（１，１，３，３－テトラメチルブチル）アミノ－１，３，５－トリアジン－２，４－ジイル｝｛（２，２，６，６－テトラメチル－４－ピペリジル）イミノ｝ヘキサメチレン｛２，２，６，６－テトラメチル－４－ピペリジル）イミノ｝］（キマソーブ（登録商標）９４４ＬＤ、ＢＡＳＦジャパン社製）、コハク酸ジメチル－１－（２ヒドロキシエチル）－４－ヒドロキシ－２，２，６，６－テトラメチル－４－ピペリジン重縮合物（チヌビン（登録商標）６２２ＬＤ、ＢＡＳＦジャパン社製）、２－［［３，５－ビス（１，１－ジメチルエチル）－４－ヒドロキシフェニル］メチル］－２－ブチルプロパン二酸ビス［１，２，２，６，６－ペンタメチル－４－ピペリジニル］（チヌビン（登録商標）１４４、ＢＡＳＦジャパン社製）、ジブチルアミン１，３，５－トリアジン・Ｎ，Ｎ－ビス（２，２，６，６－テトラメチル－４－ピペリジル－１，６－ヘキサメチレンジアミン・Ｎ－（２，２，６，６－テトラメチル－４－ピペリジル）ブチルアミンの重縮合物（キマソーブ（登録商標）２０２０ＦＤＬ、ＢＡＳＦジャパン社製）、２－（４，６－ジフェニル－１，３，５－トリアジン－２－イル）－５－（ヘキシルオキシ）－フェノール（チヌビン（登録商標）１５７７ＦＦ、ＢＡＳＦジャパン社製）、Ｎ，Ｎ’，４，７－テトラキス〔４，６－ビス［Ｎ－ブチル－Ｎ－（１，２，２，６，６－ペンタメチル－４－ピペリジル）アミノ]－１，３，５－トリアジン－２－イル〕－４，７－ジアザデカン－1，１０－ジアミン（ＳＡＢＯ ＳＴＡＢ（登録商標）ＵＶ１１９、ＳＡＢＯ社製）などが挙げられる。中でも、２，２，６，６－テトラメチルピペリジン構造及びトリアジン構造を含むキマソーブ（登録商標）９４４ＬＤ又はキマソーブ（登録商標）２０２０ＦＤ、ＳＡＢＯ ＳＴＡＢ（登録商標）ＵＶ１１９を用いることが好ましい。ヒンダードアミン化合物としては１種を単独で用いてもよく、２種以上を併用してもよい。なお、上記は例示であり同等機能及び構造を有する試薬及び工業原料であってもよい。
Examples of the hindered amine compound include, but are not limited to, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{ (2,2,6,6-tetramethyl-4-piperidyl)imino} hexamethylene {2,2,6,6-tetramethyl-4-piperidyl)imino}] (Kimasorb (registered trademark) 944LD, BASF Japan) ), dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethyl-4-piperidine polycondensate (Tinuvin (registered trademark) 622LD, manufactured by BASF Japan), 2-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-2-butylpropanedioate bis[1,2,2,6,6-pentamethyl-4-piperidinyl] (tinuvin (registered trademark) 144, manufactured by BASF Japan), dibutylamine 1,3,5-triazine N,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexa Polycondensate of methylenediamine/N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine (Chimasorb (registered trademark) 2020FDL, manufactured by BASF Japan), 2-(4,6-diphenyl-1 , 3,5-triazin-2-yl)-5-(hexyloxy)-phenol (tinuvin (registered trademark) 1577FF, manufactured by BASF Japan), N,N′,4,7-tetrakis[4,6-bis [N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-1,3,5-triazin-2-yl]-4,7-diazadecane-1,10- Diamine (SABO STAB (registered trademark) UV119, manufactured by SABO), etc. Among them, Chimasorb (registered trademark) 944LD or Chimasorb (registered trademark) containing 2,2,6,6-tetramethylpiperidine structure and triazine structure 2020FD, SABO STAB (registered trademark) UV119 is preferably used.As the hindered amine compound, one type may be used alone, or two or more types may be used in combination.The above are examples, equivalent functions and structures may be reagents and industrial raw materials having
本発明においては、水を用いた液体接触法にてエレクトレット化を行う場合においては、酸化亜鉛粒子の分散性や機能性を増強するために用いられる分散剤及び界面活性剤などの添加剤は水に対する溶出性を小さくすることが好ましく、上記の含窒素化合物と兼ねることも好ましい。極性基を有することで酸化亜鉛粒子との親和性と有するとともにポリオレフィン樹脂とも相溶性をもち、かつ電荷安定性を維持したままエレクトレットの親水性を高めるためである。親水性に関しては液体接触法における荷電効率及び抗菌、抗ウイルス、抗アレルゲン性など水が介在する機能性に対して有利な効果を有する。この場合は、キマソーブ（登録商標）９４４ＬＤ又はキマソーブ（登録商標）２０２０ＦＤ、ＳＡＢＯ ＳＴＡＢ（登録商標） ＵＶ１１９など、トリアジン構造を有し高分子のであることが好ましい。これらはマスターバッチ又はコンパウンド製造時、もしくは最終形状（例えば各種繊維状物）への成形時に添加することができる。
In the present invention, when electretization is performed by a liquid contact method using water, additives such as dispersants and surfactants used to enhance the dispersibility and functionality of zinc oxide particles are water. It is preferable to reduce the elution with respect to, and it is also preferable to combine with the above nitrogen-containing compound. This is because having a polar group has affinity with zinc oxide particles, has compatibility with polyolefin resin, and enhances the hydrophilicity of the electret while maintaining charge stability. Hydrophilicity has a beneficial effect on charging efficiency in liquid contact methods and water-mediated functionalities such as antibacterial, antiviral, and antiallergenic properties. In this case, it is preferably a polymer having a triazine structure, such as Kimasorb (registered trademark) 944LD, Kimasorb (registered trademark) 2020FD, SABO STAB (registered trademark) UV119, and the like. These can be added during masterbatch or compound production, or during molding into final shapes (eg, various fibrous materials).
本発明は、酸化亜鉛粒子を含有したポリオレフィン樹脂から成るエレクトレットであり、他にも例えば、各種結晶核剤、脂肪酸金属塩、上記帯電向上剤とは異なるヒンダードアミン、ヒンダードフェノール系酸化防止剤、リン系酸化防止剤、硫黄系酸化防止剤、紫外線吸収剤、顔料、などを必要に応じて添加することも可能である。とりわけ、ソルビトール系及びトリスアミド系等の溶解型結晶核剤及び脂肪酸マグネシウム、脂肪酸アルミニウムがエレクトレットの電荷安定化に効果的であり、分散性や親水化を促進する薬剤を添加した場合における電荷安定性低下を抑制することができる。
The present invention relates to an electret comprising a polyolefin resin containing zinc oxide particles, which may also include, for example, various crystal nucleating agents, fatty acid metal salts, hindered amines different from the above charge enhancers, hindered phenolic antioxidants, phosphorus Antioxidants such as antioxidants, sulfur antioxidants, UV absorbers, pigments, etc. may be added as necessary. In particular, soluble crystal nucleating agents such as sorbitol and trisamides, fatty acid magnesium, and fatty acid aluminum are effective in stabilizing the charge of the electret. can be suppressed.
また、脂肪酸アミド、脂肪酸及び脂肪酸金属塩、パーフルオロ誘導体からなる滑剤成分を添加することも酸化亜鉛粒子混合時におけるノズル部での塊状物付着やノズル閉塞の抑制に好適である。
Addition of a lubricant component composed of fatty acid amide, fatty acid, fatty acid metal salt, and perfluoro derivative is also suitable for suppressing clumps adhering to the nozzle and clogging the nozzle when zinc oxide particles are mixed.
本発明においては、エレクトレットとしての電荷安定性評価は、ＴＳＣ（熱刺激電流）法を用いることができる。具体的には、（１）成形体を荷電してエレクトレットとする。（２）エレクトレットの両面を挟んで２枚の電極を対向させて配置する。（３）エレクトレット両面の電極に高インピーダンスのピコアンメーターを接続する。（４）３０℃以下の加熱槽に入れ一旦短絡させた後に、設定条件２５℃から５℃／ｍｉｎにてエレクトレットの構成素材のうち最も高融点のポリオレフィンの融点＋１０℃以上まで昇温する。（５）昇温すると、トラップされた電荷が脱分極して電流が流れるので、電極温度を横軸、電流値を縦軸としてプロットする。これにより各温度における電荷移動特性を測定することができる。ＴＳＣ法においては接触法及び非接触法があるが、感度及び昇温前における短絡操作を行うことで評価結果を安定的に取得する観点から、本発明では接触法を用いる。なお、ＴＳＣ法の脱分極温度がエレクトレットの電荷安定性及びフィルターとしての性能安定性と関連づけられることは公知である（例えば、大阪工業大学紀要,６６（１),１－１８、日本国特許第３１９９９４７号など）。また本発明者は、ＴＳＣ法を用いるために用いるコロナ荷電法によるエレクトレットと液体接触法にて得られるエレクトレットの両者において、電荷安定性に相関があることを見いだしている。
In the present invention, the TSC (thermally stimulated current) method can be used to evaluate the charge stability of the electret. Specifically, (1) the compact is charged to form an electret. (2) Two electrodes are placed facing each other on both sides of the electret. (3) Connect a high-impedance picoammeter to the electrodes on both sides of the electret. (4) After being placed in a heating bath at 30° C. or lower and short-circuited, the temperature is raised from 25° C. at a rate of 5° C./min to the melting point of polyolefin, which has the highest melting point among the constituent materials of the electret, +10° C. or higher. (5) When the temperature rises, the trapped charge is depolarized and current flows, so the electrode temperature is plotted on the horizontal axis and the current value is plotted on the vertical axis. This makes it possible to measure charge transfer characteristics at each temperature. In the TSC method, there are a contact method and a non-contact method, but the contact method is used in the present invention from the viewpoint of obtaining stable evaluation results by performing a short-circuit operation before raising the temperature and sensitivity. It is known that the depolarization temperature of the TSC method is associated with the charge stability of the electret and the performance stability as a filter (for example, Osaka Institute of Technology Bulletin, 66 (1), 1-18, Japanese Patent No. 3199947, etc.). The inventors have also found that there is a correlation in charge stability between electrets obtained by the corona charging method used for the TSC method and electrets obtained by the liquid contact method.
上記（１）では、ＴＳＣ法において十分な脱分極電流を観察できるように、厚み方向において電荷（量及び極性）を偏在せしめるためにコロナ放電法を用いる。ＴＳＣ法における測定結果に影響を与えないように、荷電時の雰囲気及び試料温度は３０℃以下とする。本発明におけるコロナ放電法は酸化やエッチング等の表面処理を目的としていないため、エレクトレットの製造及び研究に用いる機器及び条件であることが肝要である。
In (1) above, the corona discharge method is used to unevenly distribute the charges (amount and polarity) in the thickness direction so that a sufficient depolarizing current can be observed in the TSC method. The atmosphere and sample temperature during charging should be 30° C. or less so as not to affect the measurement results in the TSC method. Since the corona discharge method in the present invention is not intended for surface treatment such as oxidation or etching, it is essential that the equipment and conditions are used for manufacturing and researching electrets.
上記荷電を行った後には、雰囲気温度３０℃以下の環境にて１０分以内にＴＳＣ法による測定を開始する。エレクトレット製造後に輸送、保管、加熱等の履歴を経たものに関しては、予め前述の方法にて再度荷電によりエレクトレット化して測定することが必要である。本発明におけるＴＳＣ法による評価は、成形体材料が有する本質的な熱に対する電荷安定性を評価することが目的であり、各種加工及び時間経過による電荷量変化の影響を排除するためである。すなわち、各種履歴（時間・温度など）を経た繊維状物、積層体などであっても、エレクトレット部分を分離し、荷電後にＴＳＣ測定を行うことで、脱分極の生じる熱履歴（温度および時間）の評価を行うことが肝要である。言い換えれば、高ＱＦと以下のａ／ｂ比を有するものが、濾過特性と、電荷安定性に優れたエレクトレット及びエレクトレットフィルターである。
After performing the charging, start measurement by the TSC method within 10 minutes in an environment with an ambient temperature of 30°C or less. In the case of an electret that has undergone a history of transportation, storage, heating, etc. after production, it is necessary to electretize the electret again by the above-described method in advance and measure it. The purpose of the evaluation by the TSC method in the present invention is to evaluate the intrinsic charge stability against heat of the molded product material, and to eliminate the effects of changes in the amount of charge due to various processes and the passage of time. That is, even if the fibrous material or laminate has undergone various histories (time, temperature, etc.), the electret portion can be separated, charged, and then subjected to TSC measurement. It is essential to evaluate In other words, having a high QF and the following a/b ratios are electrets and electret filters with good filtration properties and charge stability.
本発明においては、ＴＳＣ法にて測定した５０～１００℃における脱分極電流の最大値をａとし１００℃以上における脱分極電流の最大値をｂとした場合に、ａ／ｂ（／は除算を意味する）が０．３以下であることが好ましく、より好ましくは０．２以下であり、最も好ましくは０．１以下である。上記に示す電流の最大値はデータとして連続性を有する妥当な値を用いることが肝要であり、ノイズによる瞬間的なスパイク値及び、短絡電流による異常値を除いたものを取り扱い、前後の数値から鑑みて妥当な数値にて判断する。１００℃までと１００℃以上の最大値において電流極性が異なる場合には、両者の絶対値を除することとする。ａ／ｂの値が小さいほど１００℃を下回る脱分極の比率が小であり、プリーツなどの熱加工工程、輸送、保管における電荷減衰値が小さく実用性に優れたエレクトレットとなる。ａ／ｂの値が０．３を超え、電荷安定性に劣るものにおいては５０℃～１５０℃程度まで連続した脱分極が観測され電荷量の低下が著しい。なお、本発明においては、脱分極電荷量をａ／ｂ比として表しており、コロナ荷電時における脱分極電荷量が高温側において大きいことが好ましいのは言うまでもない。
In the present invention, when a is the maximum value of depolarization current at 50 to 100° C. measured by the TSC method and b is the maximum value of depolarization current at 100° C. or higher, a/b (/ is divided is preferably 0.3 or less, more preferably 0.2 or less, and most preferably 0.1 or less. It is important to use a reasonable value with continuity as the data for the maximum current value shown above. Judgment is made based on reasonable figures. If the current polarities are different between the maximum value up to 100° C. and the maximum value above 100° C., the absolute values of both are divided. The smaller the value of a/b, the smaller the ratio of depolarization below 100° C., the smaller the charge decay value in thermal processing such as pleating, transportation, and storage, making the electret excellent in practical use. When the a/b value exceeds 0.3 and the charge stability is poor, continuous depolarization is observed up to about 50° C. to 150° C., and the amount of charge decreases significantly. In the present invention, the amount of depolarization charge is expressed as an a/b ratio, and it goes without saying that the amount of depolarization charge during corona charging is preferably large on the high temperature side.
１００℃以上における脱分極電流は最大値を示すピーク温度及び開始温度が高温かつ半値幅が狭いものが好ましく、例えばピーク温度として１２０℃以上であり、より好ましくは１３０℃以上であり、最も好ましくは１４０℃以上である。立ち上がり温度としては８０℃以上が好ましく、より好ましくは９０℃以上であり、更に好ましくは１００℃以上であり、最も好ましくは１１０℃以上である。立ち上がり温度はピーク前後の計測値の接線同士の交点として求められる。
The depolarization current at 100°C or higher preferably has a peak temperature at which the maximum value and a start temperature are high and has a narrow half-value width. For example, the peak temperature is 120°C or higher, more preferably 130°C or higher, and most preferably. 140° C. or higher. The rising temperature is preferably 80° C. or higher, more preferably 90° C. or higher, still more preferably 100° C. or higher, and most preferably 110° C. or higher. The rise temperature is obtained as the intersection of the tangents of the measured values before and after the peak.
本発明のエレクトレットは必要とされるあらゆる形状の成形体とすることができるが、繊維状物であると利用に好適である。繊維状物とは、長繊維または短繊維からなる織編物、不織布、綿状物等の繊維状物や延伸フィルムから得られる繊維状物を含むものであり、用途に応じて適当な形状及び厚みに成形することができる。エレクトレットをフィルター用途として利用する場合は、不織布であることが最も好ましい。
The electret of the present invention can be made into a molded body of any required shape, but a fibrous material is suitable for use. The fibrous materials include fibrous materials such as woven and knitted fabrics, non-woven fabrics, and cotton-like materials made of long fibers or short fibers, and fibrous materials obtained from stretched films, and have an appropriate shape and thickness depending on the application. can be molded into When the electret is used as a filter, it is most preferably a nonwoven fabric.
不織布を得る方法としては、単成分繊維、芯鞘繊維やサイドバイサイド繊維といった複合繊維、分割繊維等の短繊維をカーディング、エアレイド、湿式抄紙法などによりシート化する方法、連続繊維よりなるスパンボンド法、メルトブロー法、エレクトロスピニング法、フォーススピニング法、レーザー延伸法などによりシート化する方法など、従来公知の方法を用いることが可能である。なかでも、紡績油剤及び溶剤を使用しない観点からメルトブロー法、溶融エレクトロスピニング法、溶融フォーススピニング法、スパンボンド法、レーザー延伸法で得られる長繊維不織布がエレクトレット用途としてより好ましい。
Methods for obtaining nonwoven fabrics include a method of sheeting monocomponent fibers, composite fibers such as core-sheath fibers and side-by-side fibers, and short fibers such as split fibers by carding, airlaid, wet papermaking, etc., and a spunbond method using continuous fibers. , a melt blowing method, an electrospinning method, a force spinning method, a method of forming a sheet by a laser stretching method, and the like, and other conventionally known methods can be used. Among them, long-fiber nonwoven fabrics obtained by a meltblowing method, a melt electrospinning method, a melt force spinning method, a spunbond method, or a laser drawing method are more preferable for electret applications from the viewpoint of not using a spinning oil and a solvent.
本発明の繊維状物に用いられる繊維の平均繊維径（直径）は、０．００１～１００μｍであることが好ましく、０．００５～２０μｍであることがより好ましく、０．０１～１０μｍであることがさらに好ましく、０．０２～５μｍであることが特に好ましく、０．０３～３μｍであることが最も好ましい。平均繊維径が１００μｍよりも太い場合には実用的な捕集効率を得ることが困難であり、電荷減衰時の効率低下が大きい。繊維の直径が０．００１μｍよりも細い場合にはエレクトレットとしての電荷を付与することが困難である。
The average fiber diameter (diameter) of the fibers used in the fibrous material of the present invention is preferably 0.001 to 100 μm, more preferably 0.005 to 20 μm, and 0.01 to 10 μm. is more preferred, 0.02 to 5 μm is particularly preferred, and 0.03 to 3 μm is most preferred. If the average fiber diameter is larger than 100 μm, it is difficult to obtain a practical collection efficiency, and the efficiency is greatly reduced during charge decay. When the diameter of the fiber is smaller than 0.001 μm, it is difficult to impart an electric charge as an electret.
本発明における繊維状物は単独の製法、素材からなる均一物であってもよく、製法、素材及び繊維径の異なる２種以上の素材を用いてなる混合物であってもよい。エレクトレット特性を有する部分の少なくとも一部が本発明の組成であることが特性発現に必要なことである。
The fibrous material in the present invention may be a uniform material made of a single manufacturing method and material, or a mixture of two or more materials with different manufacturing methods, materials and fiber diameters. At least a part of the portion having electret properties must be the composition of the present invention for manifestation of the properties.
本発明のエレクトレットは必要に応じて他の構成部材と併用することができる。本発明のエレクトレットをフィルターとして用いる場合には、例えば、プレフィルター層、繊維保護層、補強部材、または機能性繊維層などと組み合わせて用いることも好ましい。本発明のエレクトレットを用いたエレクトレットフィルターも本発明の範疇に含まれる。
The electret of the present invention can be used together with other constituent members as necessary. When the electret of the present invention is used as a filter, it is preferably used in combination with, for example, a prefilter layer, a fiber protection layer, a reinforcing member, or a functional fiber layer. An electret filter using the electret of the present invention is also included in the scope of the present invention.
本発明のエレクトレットが不織布等の繊維状物である場合に関しては、微細粒子の捕集特性をエレクトレットの電荷量又は電荷安定性の評価に用いることもできる。特に液体接触法においては厚み方向への電荷の偏在が不十分であり、ＴＳＣ法による直接評価が困難な場合の評価法として有効である。
When the electret of the present invention is a fibrous material such as a nonwoven fabric, the collection properties of fine particles can also be used to evaluate the charge amount or charge stability of the electret. In particular, the liquid contact method is effective as an evaluation method when the uneven distribution of charges in the thickness direction is insufficient and direct evaluation by the TSC method is difficult.
本発明においては、微細粒の捕集特性を用いて電荷量又は電荷安定性を評価する方法としては、電荷量と関連するパラメータとして濾材品質係数（ＱＦ値）、電荷安定性を評価する方法としては、各種処理前後における透過率の自然対数比（本明細書では性能維持率と称する）を用いる。粒子としては人為的に発生させたものを平衡帯電化してもよいし、大気塵を用いてもよい。検出器に関しては粒子径の範囲を限定できるものであれば、濃度及び個数いずれが得られるものであってもよい。評価条件としては、静電引力が支配的であることが好ましく、一例としては通過風速として１０ｃｍ／ｓとし、微差圧計を用い試料前後の圧力差、レーザーパーティクルカウンターを用い直径０．３～０．５μｍ区間における試料前後の粒子個数濃度を比較することで粒子透過率及び粒子捕集効率、濾材品質係数、性能維持率を各々算出する。各々の関係を下記に示す。
In the present invention, as a method of evaluating the charge amount or charge stability using the collection characteristics of fine particles, a filter medium quality factor (QF value) as a parameter related to the charge amount, and a method of evaluating charge stability uses the natural logarithmic ratio of transmittance before and after various treatments (herein referred to as performance maintenance ratio). As the particles, those artificially generated may be charged in equilibrium, or atmospheric dust may be used. As far as the detector is capable of limiting the range of particle sizes, either concentration or number may be obtained. As evaluation conditions, it is preferable that electrostatic attraction is dominant, and as an example, the passing wind speed is 10 cm / s, the pressure difference before and after the sample using a differential pressure gauge, and the diameter using a laser particle counter of 0.3 to 0. By comparing the particle number concentrations before and after the sample in the 5 μm section, the particle permeability, particle collection efficiency, filter medium quality factor, and performance maintenance rate are calculated. Each relationship is shown below.
粒子透過率[－]＝（試料下流側の粒子個数濃度）／（試料上流側の粒子個数濃度）
粒子捕集効率[％]＝（１－粒子透過率[－]）×１００
濾材品質係数（ＱＦ値）[ｍｍＡｑ-１]＝－（ｌｎ（粒子透過率[－]）／（通気抵抗[ｍｍＡｑ]））
性能維持率[－]＝ｌｎ（処理後の粒子透過率[－]）／ｌｎ（処理前の粒子透過率[－]） Particle transmittance [-] = (particle number concentration on the downstream side of the sample) / (particle number concentration on the upstream side of the sample)
Particle collection efficiency [%] = (1-particle transmittance [-]) x 100
Filter media quality factor (QF value) [mmAq -1 ] = - (ln (particle permeability [-]) / (ventilation resistance [mmAq]))
Performance retention rate [-] = ln (particle transmittance after treatment [-]) / ln (particle transmittance before treatment [-])
粒子捕集効率[％]＝（１－粒子透過率[－]）×１００
濾材品質係数（ＱＦ値）[ｍｍＡｑ-１]＝－（ｌｎ（粒子透過率[－]）／（通気抵抗[ｍｍＡｑ]））
性能維持率[－]＝ｌｎ（処理後の粒子透過率[－]）／ｌｎ（処理前の粒子透過率[－]） Particle transmittance [-] = (particle number concentration on the downstream side of the sample) / (particle number concentration on the upstream side of the sample)
Particle collection efficiency [%] = (1-particle transmittance [-]) x 100
Filter media quality factor (QF value) [mmAq -1 ] = - (ln (particle permeability [-]) / (ventilation resistance [mmAq]))
Performance retention rate [-] = ln (particle transmittance after treatment [-]) / ln (particle transmittance before treatment [-])
上記における濾材品質係数ＱＦの値は、エレクトレット化されていない繊維状物を用いた場合には概ね０．１以下である。エレクトレットをフィルター用途とする場合は、０．５以上が好ましくより好ましくは１．０以上であり、更に好ましくは１．１以上であり、最も好ましくは１．２以上である。水を用いた液体接触によるエレクトレット化法の場合は、加熱乾燥工程あり、またフィルター用途においてはプリーツ工程や長期保管が行われる場合がある。したがって、上記の濾材品質係数ＱＦは、エレクトレット化直後のみならず加熱処理後に維持してなることが好ましい。
The value of the filter medium quality factor QF in the above is generally 0.1 or less when fibrous materials that have not been electretized are used. When the electret is used as a filter, it is preferably 0.5 or more, more preferably 1.0 or more, still more preferably 1.1 or more, and most preferably 1.2 or more. In the case of an electretization method by liquid contact using water, there is a heat drying process, and in filter applications, a pleating process and long-term storage may be performed. Therefore, it is preferable that the filter medium quality factor QF is maintained not only immediately after electretization but also after heat treatment.
本発明のエレクトレットは、エレクトレットとしての機能と酸化亜鉛粒子の機能を両立することが可能であり、特に繊維状物及びフィルターとして、集塵、保護、通気、防汚、防水などの機能により幅広く用いることができる。また酸化亜鉛粒子が有する抗菌性、抗カビ性、抗ウイルス性、抗アレルゲン性などの機能を組み合わせて、防塵マスク、各種空調用エレメント、空気清浄機、キャビンフィルター、各種装置の保護を目的としたフィルターとして好適に用いることができる。また、酸化亜鉛粒子単体の機能として用いるのみならず、放電装置、電気集塵装置、光照射装置などと組み合わせた空調機器などにおいても好適に用いることができる。
The electret of the present invention can have both the function of an electret and the function of zinc oxide particles, and is widely used as a fibrous material and a filter due to its functions such as dust collection, protection, ventilation, antifouling, and waterproofing. be able to. In addition, by combining the antibacterial, antifungal, antiviral, and antiallergenic properties of zinc oxide particles, we aim to protect dust masks, various air conditioning elements, air purifiers, cabin filters, and various devices. It can be suitably used as a filter. In addition, it can be used not only as a function of the zinc oxide particles alone, but also in an air conditioner combined with a discharge device, an electrostatic precipitator, a light irradiation device, or the like.
以下実施例によって本発明をさらに詳述するが、下記実施例は本発明を制限するものではなく、本発明の趣旨を逸脱しない範囲で変更実施をすることは全て本発明の技術的範囲に包含される。初めに、測定方法について説明する。
The present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention, and all changes and implementations within the scope of the present invention are included in the technical scope of the present invention. be done. First, the measurement method will be explained.
（粒子捕集効率）
以下の式にて算出した。
捕集効率[％]＝（１－粒子透過率[－]）×１００
なお、試料の荷電後の風乾直後に測定した数値を初期捕集効率とした。 (Particle collection efficiency)
It was calculated by the following formula.
Collection efficiency [%] = (1-particle transmittance [-]) x 100
The value measured immediately after the sample was air-dried after charging was taken as the initial collection efficiency.
以下の式にて算出した。
捕集効率[％]＝（１－粒子透過率[－]）×１００
なお、試料の荷電後の風乾直後に測定した数値を初期捕集効率とした。 (Particle collection efficiency)
It was calculated by the following formula.
Collection efficiency [%] = (1-particle transmittance [-]) x 100
The value measured immediately after the sample was air-dried after charging was taken as the initial collection efficiency.
（濾材品質係数（ＱＦ値））
エレクトレット電荷量及びフィルター性能の指標としては下記で定められるＱＦ値を用いた。
ＱＦ[ｍｍＡｑ-１]＝－（ｌｎ（粒子透過率[－]）／（通気抵抗[ｍｍＡｑ]）
（粒子透過率）
試料をアダプターに装着し、光散乱式粒子計数装置リオン社製ＫＣ－０１Ｅを用いて以下の条件にて、粒子透過率を算出した。
評価粒子：大気塵粒子
風速 ：１０ｃｍ／ｓ
効率算出：光散乱計数法による０．３～０．５μｍ間の粒子個数
粒子透過率[－]＝（試料下流側の粒子個数濃度）／（試料上流側の粒子個数濃度）
（通気抵抗）
試料をアダプターに装着し、微差圧計を接続した配管を上下に連結、１０ｃｍ／ｓにて通風し、絞りの無い状態での通気抵抗（圧力損失）（ｍｍＡｑ）を計測した。 (Filter material quality factor (QF value))
The QF value defined below was used as an index of the electret charge amount and filter performance.
QF [mmAq -1 ] = - (ln (particle permeability [-]) / (ventilation resistance [mmAq])
(particle transmittance)
The sample was attached to an adapter, and the particle transmittance was calculated under the following conditions using a light scattering particle counter KC-01E manufactured by Rion.
Particles to be evaluated: Atmospheric dust particles Wind speed: 10 cm/s
Efficiency calculation: Particle number between 0.3 and 0.5 μm by light scattering counting method Particle transmittance [-] = (particle number concentration on the downstream side of the sample) / (particle number concentration on the upstream side of the sample)
(ventilation resistance)
A sample was attached to an adapter, pipes connected to a differential pressure gauge were connected vertically, and ventilation was performed at 10 cm/s to measure airflow resistance (pressure loss) (mmAq) in a state without restriction.
エレクトレット電荷量及びフィルター性能の指標としては下記で定められるＱＦ値を用いた。
ＱＦ[ｍｍＡｑ-１]＝－（ｌｎ（粒子透過率[－]）／（通気抵抗[ｍｍＡｑ]）
（粒子透過率）
試料をアダプターに装着し、光散乱式粒子計数装置リオン社製ＫＣ－０１Ｅを用いて以下の条件にて、粒子透過率を算出した。
評価粒子：大気塵粒子
風速 ：１０ｃｍ／ｓ
効率算出：光散乱計数法による０．３～０．５μｍ間の粒子個数
粒子透過率[－]＝（試料下流側の粒子個数濃度）／（試料上流側の粒子個数濃度）
（通気抵抗）
試料をアダプターに装着し、微差圧計を接続した配管を上下に連結、１０ｃｍ／ｓにて通風し、絞りの無い状態での通気抵抗（圧力損失）（ｍｍＡｑ）を計測した。 (Filter material quality factor (QF value))
The QF value defined below was used as an index of the electret charge amount and filter performance.
QF [mmAq -1 ] = - (ln (particle permeability [-]) / (ventilation resistance [mmAq])
(particle transmittance)
The sample was attached to an adapter, and the particle transmittance was calculated under the following conditions using a light scattering particle counter KC-01E manufactured by Rion.
Particles to be evaluated: Atmospheric dust particles Wind speed: 10 cm/s
Efficiency calculation: Particle number between 0.3 and 0.5 μm by light scattering counting method Particle transmittance [-] = (particle number concentration on the downstream side of the sample) / (particle number concentration on the upstream side of the sample)
(ventilation resistance)
A sample was attached to an adapter, pipes connected to a differential pressure gauge were connected vertically, and ventilation was performed at 10 cm/s to measure airflow resistance (pressure loss) (mmAq) in a state without restriction.
（性能維持率）
電荷安定性を評価するため、熱負荷による処理前後の粒子透過率の対数を比較した。熱負荷の処理条件として、試料両面をアルミ箔にて短絡させた状態とし、１００℃の熱風乾燥機中に３０分間静置した。なお処理前は、荷電後、２５℃風乾直後とした。
性能維持率[－]＝ｌｎ（処理後の粒子透過率[－]）／ｌｎ（処理前の粒子透過率[－]） (Performance maintenance rate)
To assess charge stability, the logarithm of particle permeability before and after treatment with a thermal load was compared. As a heat load treatment condition, both surfaces of the sample were short-circuited with aluminum foil, and the sample was allowed to stand in a hot air dryer at 100° C. for 30 minutes. Before the treatment, it was immediately after air drying at 25° C. after charging.
Performance retention rate [-] = ln (particle transmittance after treatment [-]) / ln (particle transmittance before treatment [-])
電荷安定性を評価するため、熱負荷による処理前後の粒子透過率の対数を比較した。熱負荷の処理条件として、試料両面をアルミ箔にて短絡させた状態とし、１００℃の熱風乾燥機中に３０分間静置した。なお処理前は、荷電後、２５℃風乾直後とした。
性能維持率[－]＝ｌｎ（処理後の粒子透過率[－]）／ｌｎ（処理前の粒子透過率[－]） (Performance maintenance rate)
To assess charge stability, the logarithm of particle permeability before and after treatment with a thermal load was compared. As a heat load treatment condition, both surfaces of the sample were short-circuited with aluminum foil, and the sample was allowed to stand in a hot air dryer at 100° C. for 30 minutes. Before the treatment, it was immediately after air drying at 25° C. after charging.
Performance retention rate [-] = ln (particle transmittance after treatment [-]) / ln (particle transmittance before treatment [-])
（ＴＳＣ法による脱分極電流測定）
熱刺激電流測定装置を用い以下の条件にて測定を行った。なお、ポリプロピレン樹脂試料であるため測定終点を１８０℃とした。
・コロナ荷電：平板針電極－千鳥配置、１０ｍｍ間隔、アース面に０．５ｍｍ厚のシリコンゴムシートを設置し、ギャップ１０ｍｍ、印可電圧２０ＫＶ、荷電時間３０秒、にて試料（繊維シート）を荷電した。
・ＴＳＣ電極：円形（直径２０ｍｍ）１対の電極に試料（直径２５ｍｍ）を挟んで両電極を対向させた。両電極表面は試料表面と接触させた。
・温度条件：２５℃～１８０℃を５℃／ｍｉｎで昇温させた。
・その他：電極間に試料をセット後、両電極を一旦短絡し電流値のゼロ点とする。得られたデータを、横軸を温度℃、縦軸を電流値[－]とし、５０～１００℃におけるピーク高さをa、１００℃～１８０℃におけるピーク高さをｂとし、ａ／ｂ値を求めた。 (Depolarization current measurement by TSC method)
Measurement was performed under the following conditions using a thermally stimulated current measuring device. In addition, since it is a polypropylene resin sample, the end point of the measurement was set at 180°C.
・Corona charging: Plain needle electrode-staggered arrangement, 10 mm interval, 0.5 mm thick silicon rubber sheet placed on the ground plane, gap 10 mm, applied voltage 20 KV, charging time 30 seconds, charging the sample (fiber sheet) bottom.
TSC electrode: A pair of circular (20 mm diameter) electrodes were opposed to each other with a sample (25 mm diameter) sandwiched therebetween. Both electrode surfaces were brought into contact with the sample surface.
- Temperature condition: 25°C to 180°C was raised at a rate of 5°C/min.
・Others: After setting the sample between the electrodes, both electrodes are temporarily short-circuited to set the current value to zero. For the obtained data, the horizontal axis is the temperature ° C., the vertical axis is the current value [-], the peak height at 50 to 100 ° C. is a, the peak height at 100 ° C. to 180 ° C. is b, and the a / b value asked for
熱刺激電流測定装置を用い以下の条件にて測定を行った。なお、ポリプロピレン樹脂試料であるため測定終点を１８０℃とした。
・コロナ荷電：平板針電極－千鳥配置、１０ｍｍ間隔、アース面に０．５ｍｍ厚のシリコンゴムシートを設置し、ギャップ１０ｍｍ、印可電圧２０ＫＶ、荷電時間３０秒、にて試料（繊維シート）を荷電した。
・ＴＳＣ電極：円形（直径２０ｍｍ）１対の電極に試料（直径２５ｍｍ）を挟んで両電極を対向させた。両電極表面は試料表面と接触させた。
・温度条件：２５℃～１８０℃を５℃／ｍｉｎで昇温させた。
・その他：電極間に試料をセット後、両電極を一旦短絡し電流値のゼロ点とする。得られたデータを、横軸を温度℃、縦軸を電流値[－]とし、５０～１００℃におけるピーク高さをa、１００℃～１８０℃におけるピーク高さをｂとし、ａ／ｂ値を求めた。 (Depolarization current measurement by TSC method)
Measurement was performed under the following conditions using a thermally stimulated current measuring device. In addition, since it is a polypropylene resin sample, the end point of the measurement was set at 180°C.
・Corona charging: Plain needle electrode-staggered arrangement, 10 mm interval, 0.5 mm thick silicon rubber sheet placed on the ground plane, gap 10 mm, applied voltage 20 KV, charging time 30 seconds, charging the sample (fiber sheet) bottom.
TSC electrode: A pair of circular (20 mm diameter) electrodes were opposed to each other with a sample (25 mm diameter) sandwiched therebetween. Both electrode surfaces were brought into contact with the sample surface.
- Temperature condition: 25°C to 180°C was raised at a rate of 5°C/min.
・Others: After setting the sample between the electrodes, both electrodes are temporarily short-circuited to set the current value to zero. For the obtained data, the horizontal axis is the temperature ° C., the vertical axis is the current value [-], the peak height at 50 to 100 ° C. is a, the peak height at 100 ° C. to 180 ° C. is b, and the a / b value asked for
（平均繊維径）
走査型顕微鏡を用い、画像の視野サイズとして９０μｍ×９０μｍとなるように複数の画像取得を行った後、同一繊維にて重複しないように５０本の繊維直径を計測した。得られた各々の数値を幾何平均することで平均繊維径を算出した。 (average fiber diameter)
Using a scanning microscope, a plurality of images were obtained with a visual field size of 90 μm×90 μm, and then 50 fiber diameters were measured so as not to overlap the same fibers. The average fiber diameter was calculated by geometrically averaging the obtained numerical values.
走査型顕微鏡を用い、画像の視野サイズとして９０μｍ×９０μｍとなるように複数の画像取得を行った後、同一繊維にて重複しないように５０本の繊維直径を計測した。得られた各々の数値を幾何平均することで平均繊維径を算出した。 (average fiber diameter)
Using a scanning microscope, a plurality of images were obtained with a visual field size of 90 μm×90 μm, and then 50 fiber diameters were measured so as not to overlap the same fibers. The average fiber diameter was calculated by geometrically averaging the obtained numerical values.
（抗菌性）
抗菌性試験はＪＩＳ Ｌ １９０２における菌液吸収法にて、黄色ブドウ状球菌及び大腸菌に対して評価を行った。 (antibacterial)
In the antibacterial test, the bacterial liquid absorption method in JIS L 1902 was used to evaluate against Staphylococcus aureus and Escherichia coli.
抗菌性試験はＪＩＳ Ｌ １９０２における菌液吸収法にて、黄色ブドウ状球菌及び大腸菌に対して評価を行った。 (antibacterial)
In the antibacterial test, the bacterial liquid absorption method in JIS L 1902 was used to evaluate against Staphylococcus aureus and Escherichia coli.
（フォトルミネッセンス測定）
以下の条件にて顕微式フォトルミネッセンス測定装置を用いて、波長３５０から７００ｎｍの範囲のフォトルミネッセンスを測定した。
励起光 ：３２５ｎｍ（レーザー）、３μＷ
検出器：ＣＣＤ
測定温度：２５℃
対物レンズ：×４０ (Photoluminescence measurement)
Photoluminescence in the wavelength range of 350 to 700 nm was measured using a microphotoluminescence measuring device under the following conditions.
Excitation light: 325 nm (laser), 3 μW
Detector: CCD
Measurement temperature: 25°C
Objective lens: ×40
以下の条件にて顕微式フォトルミネッセンス測定装置を用いて、波長３５０から７００ｎｍの範囲のフォトルミネッセンスを測定した。
励起光 ：３２５ｎｍ（レーザー）、３μＷ
検出器：ＣＣＤ
測定温度：２５℃
対物レンズ：×４０ (Photoluminescence measurement)
Photoluminescence in the wavelength range of 350 to 700 nm was measured using a microphotoluminescence measuring device under the following conditions.
Excitation light: 325 nm (laser), 3 μW
Detector: CCD
Measurement temperature: 25°C
Objective lens: ×40
（１）平均粒子径０．７５μｍの酸化亜鉛粒子（ａ）を粉末状態にてフォトルミネッセンス測定を行った結果、波長３５０ｎｍ～４００ｎｍ領域のフォトルミネッセンス強度Ａと、波長５００ｎｍ～７００ｎｍ領域のフォトルミネッセンス強度Ｂとの比Ｂ／Ａは０．００４であった。
(1) As a result of photoluminescence measurement of zinc oxide particles (a) having an average particle diameter of 0.75 μm in a powder state, the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm and the photoluminescence intensity in the wavelength range of 500 nm to 700 nm were obtained. The ratio B/A to B was 0.004.
（２）ポリプロピレン樹脂中に１０質量％の含有率で酸化亜鉛粒子（ａ）（平均粒子径０．７５μｍ）が分散されたマスターバッチにおける酸化亜鉛粒子（ａ）のフォトルミネッセンス測定を行った。波長３５０ｎｍ～４００ｎｍ領域のフォトルミネッセンス強度Ａと、波長５００ｎｍ～７００ｎｍ領域のフォトルミネッセンス強度Ｂとの比Ｂ／Ａは、０．００１であった。粉末状及びマスターバッチでの酸化亜鉛粒子（ａ）に関するＢ／Ａの数値は概ね同等の結果となった。
(2) Photoluminescence measurement of zinc oxide particles (a) in a masterbatch in which zinc oxide particles (a) (average particle size 0.75 μm) were dispersed in a polypropylene resin at a content of 10% by mass was measured. The ratio B/A between the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm and the photoluminescence intensity B in the wavelength range of 500 nm to 700 nm was 0.001. The values of B/A for powdered and masterbatch zinc oxide particles (a) were almost the same.
（３）ポリプロピレン中に２０質量％の含有率で酸化亜鉛粒子（ｂ）（平均粒子径０．８μｍ）が分散されたマスターバッチにおける酸化亜鉛粒子（ｂ）フォトルミネッセンス測定を行った。波長３５０ｎｍ～４００ｎｍ領域のフォトルミネッセンス強度Ａと、波長５００ｎｍ～７００ｎｍ領域のフォトルミネッセンス強度Ｂとの比Ｂ／Ａは０．０９４であった。
(3) Zinc oxide particles (b) photoluminescence measurement was performed on a masterbatch in which zinc oxide particles (b) (average particle size 0.8 μm) were dispersed in polypropylene at a content of 20% by mass. The ratio B/A between the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm and the photoluminescence intensity B in the wavelength range of 500 nm to 700 nm was 0.094.
＜実施例１＞
ＭＦＲ１３００のポリプロピレンホモポリマーに対し、上記（２）のマスターバッチを用い、酸化亜鉛粒子（ａ）０．２５質量％（マスターバッチとして２．５質量％）、キマソーブ（登録商標）９４４ＬＤ（ＢＡＳＦジャパン社製）１質量％、ステアリン酸マグネシウム０．０７５質量％で添加し、メルトブロー装置を用い、目付３０ｇ／ｍ２、平均繊維径３．０μｍの長繊維不織布を得た。得られた不織布を網状支持体に載せ、支持体の上方２ｃｍに位置する直径０．１ｍｍφ、ピッチ０．６ｍｍのノズルから、ｐＨ６．７、導電率０．８μＳ／ｃｍのイオン交換水を１ＭＰａの圧力で噴出させた。ノズル直下の網状支持体の下方を減圧状態としたまま４ｍ／分の速度で搬送しシートの表裏について各１回ずつ処理を行った後、更に水を噴射せず減圧のみで通過させることで脱水し、２５℃にて２時間風乾を行うことでエレクトレット化を行った。 <Example 1>
For polypropylene homopolymer of MFR 1300, using the masterbatch of (2) above, zinc oxide particles (a) 0.25% by mass (2.5% by mass as a masterbatch), Chimasorb (registered trademark) 944LD (BASF Japan) (manufacturer) and 0.075% by mass of magnesium stearate were added, and a filament nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 3.0 µm was obtained using a meltblowing apparatus. The obtained nonwoven fabric was placed on a mesh support, and ion-exchanged water having a pH of 6.7 and an electrical conductivity of 0.8 μS/cm was applied from a nozzle with a diameter of 0.1 mmφ and a pitch of 0.6 mm positioned 2 cm above the support at a pressure of 1 MPa. It was ejected under pressure. The sheet was conveyed at a speed of 4 m/min while the pressure was kept under the mesh support just below the nozzle, and the front and back sides of the sheet were treated once each. Then, it was air-dried at 25° C. for 2 hours to form an electret.
ＭＦＲ１３００のポリプロピレンホモポリマーに対し、上記（２）のマスターバッチを用い、酸化亜鉛粒子（ａ）０．２５質量％（マスターバッチとして２．５質量％）、キマソーブ（登録商標）９４４ＬＤ（ＢＡＳＦジャパン社製）１質量％、ステアリン酸マグネシウム０．０７５質量％で添加し、メルトブロー装置を用い、目付３０ｇ／ｍ２、平均繊維径３．０μｍの長繊維不織布を得た。得られた不織布を網状支持体に載せ、支持体の上方２ｃｍに位置する直径０．１ｍｍφ、ピッチ０．６ｍｍのノズルから、ｐＨ６．７、導電率０．８μＳ／ｃｍのイオン交換水を１ＭＰａの圧力で噴出させた。ノズル直下の網状支持体の下方を減圧状態としたまま４ｍ／分の速度で搬送しシートの表裏について各１回ずつ処理を行った後、更に水を噴射せず減圧のみで通過させることで脱水し、２５℃にて２時間風乾を行うことでエレクトレット化を行った。 <Example 1>
For polypropylene homopolymer of MFR 1300, using the masterbatch of (2) above, zinc oxide particles (a) 0.25% by mass (2.5% by mass as a masterbatch), Chimasorb (registered trademark) 944LD (BASF Japan) (manufacturer) and 0.075% by mass of magnesium stearate were added, and a filament nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 3.0 µm was obtained using a meltblowing apparatus. The obtained nonwoven fabric was placed on a mesh support, and ion-exchanged water having a pH of 6.7 and an electrical conductivity of 0.8 μS/cm was applied from a nozzle with a diameter of 0.1 mmφ and a pitch of 0.6 mm positioned 2 cm above the support at a pressure of 1 MPa. It was ejected under pressure. The sheet was conveyed at a speed of 4 m/min while the pressure was kept under the mesh support just below the nozzle, and the front and back sides of the sheet were treated once each. Then, it was air-dried at 25° C. for 2 hours to form an electret.
評価の結果、初期捕集効率９９．９９７％、ＱＦ値１．７９、性能維持率０．９０、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０４、１００℃以降の脱分極の最大値を示すピーク温度１４３℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。
As a result of the evaluation, the initial collection efficiency was 99.997%, the QF value was 1.79, the performance maintenance rate was 0.90, the a/b value was 0.04 in the depolarization current measurement by the TSC method, and the depolarization after 100 ° C. The maximum peak temperature was 143°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
＜実施例２＞
原料と割合は実施例１と同一とし、メルトブロー装置を用い、目付を１８ｇ／ｍ２、平均繊維径２．５μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９２％、ＱＦ値１．５１、性能維持率０．８８、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０４、１００℃以降の脱分極の最大値を示すピーク温度１４４℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Example 2>
Using the same raw materials and proportions as in Example 1, a melt-blowing apparatus was used to obtain a long-fiber nonwoven fabric having a basis weight of 18 g/m 2 and an average fiber diameter of 2.5 μm. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.992%, QF value 1.51, performance maintenance rate 0.88, a/b value 0.04 in depolarization current measurement by TSC method, maximum value of depolarization after 100 ° C. The peak temperature was 144°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
原料と割合は実施例１と同一とし、メルトブロー装置を用い、目付を１８ｇ／ｍ２、平均繊維径２．５μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９２％、ＱＦ値１．５１、性能維持率０．８８、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０４、１００℃以降の脱分極の最大値を示すピーク温度１４４℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Example 2>
Using the same raw materials and proportions as in Example 1, a melt-blowing apparatus was used to obtain a long-fiber nonwoven fabric having a basis weight of 18 g/m 2 and an average fiber diameter of 2.5 μm. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.992%, QF value 1.51, performance maintenance rate 0.88, a/b value 0.04 in depolarization current measurement by TSC method, maximum value of depolarization after 100 ° C. The peak temperature was 144°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
＜実施例３＞
上記（２）のマスターバッチを用いて酸化亜鉛粒子（ａ）の濃度を１質量％としたほかは実施例２と同一とし、メルトブロー装置を用い、目付１８ｇ／ｍ２、平均繊維径２．６μｍ長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９％、ＱＦ値１．５３、性能維持率０．８６、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０６、１００℃以降の脱分極最大値を示すピーク温度１４３℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Example 3>
The same as Example 2 except that the concentration of zinc oxide particles (a) was 1% by mass using the masterbatch of (2) above, and a melt blowing apparatus was used to produce a basis weight of 18 g/m 2 and an average fiber diameter of 2.6 μm. A long fiber nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.99%, QF value 1.53, performance retention rate 0.86, a/b value 0.06 in depolarization current measurement by TSC method, peak indicating maximum depolarization after 100 ° C The temperature was 143°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
上記（２）のマスターバッチを用いて酸化亜鉛粒子（ａ）の濃度を１質量％としたほかは実施例２と同一とし、メルトブロー装置を用い、目付１８ｇ／ｍ２、平均繊維径２．６μｍ長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９％、ＱＦ値１．５３、性能維持率０．８６、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０６、１００℃以降の脱分極最大値を示すピーク温度１４３℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Example 3>
The same as Example 2 except that the concentration of zinc oxide particles (a) was 1% by mass using the masterbatch of (2) above, and a melt blowing apparatus was used to produce a basis weight of 18 g/m 2 and an average fiber diameter of 2.6 μm. A long fiber nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.99%, QF value 1.53, performance retention rate 0.86, a/b value 0.06 in depolarization current measurement by TSC method, peak indicating maximum depolarization after 100 ° C The temperature was 143°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
＜実施例４＞
上記（２）のマスターバッチを用いて酸化亜鉛粒子（ａ）の濃度を５質量％とした以外は実施例２と同一とし、メルトブロー装置を用い、目付１８ｇ／ｍ２、平均繊維径２．８μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９７％、ＱＦ値１．４５、性能維持率は０．８４、ＴＳＣ法による脱分極電流測定でのａ／ｂ値は０．１０、１００℃以降の脱分極の最大値を示すピーク温度は１３８℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。
＜実施例５＞
酸化亜鉛粒子（ａ）の粒子径を０．３μｍとし、１０質量％のマスターバッチ作成後に添加した他は実施例２と同一とし、メルトブロー装置を用い、目付１８ｇ／ｍ２、平均繊維径２．６μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９％、ＱＦ値１．４８、性能維持率０．８８、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０４、１００℃以降の脱分極の最大値を示すピーク温度は１４０℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Example 4>
The same as Example 2 except that the concentration of the zinc oxide particles (a) was changed to 5% by mass using the masterbatch of ( 2 ) above. to obtain a long fiber nonwoven fabric. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.97%, QF value 1.45, performance retention rate 0.84, a/b value in depolarization current measurement by TSC method 0.10, maximum value of depolarization after 100 ° C was 138°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
<Example 5>
The zinc oxide particles (a) had a particle diameter of 0.3 μm, and were added after preparation of a 10 % by mass masterbatch. A 6 μm long fiber nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.99%, QF value 1.48, performance maintenance rate 0.88, a/b value 0.04 in depolarization current measurement by TSC method, maximum value of depolarization after 100 ° C. The peak temperature was 140°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
上記（２）のマスターバッチを用いて酸化亜鉛粒子（ａ）の濃度を５質量％とした以外は実施例２と同一とし、メルトブロー装置を用い、目付１８ｇ／ｍ２、平均繊維径２．８μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９７％、ＱＦ値１．４５、性能維持率は０．８４、ＴＳＣ法による脱分極電流測定でのａ／ｂ値は０．１０、１００℃以降の脱分極の最大値を示すピーク温度は１３８℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。
＜実施例５＞
酸化亜鉛粒子（ａ）の粒子径を０．３μｍとし、１０質量％のマスターバッチ作成後に添加した他は実施例２と同一とし、メルトブロー装置を用い、目付１８ｇ／ｍ２、平均繊維径２．６μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９％、ＱＦ値１．４８、性能維持率０．８８、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０４、１００℃以降の脱分極の最大値を示すピーク温度は１４０℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Example 4>
The same as Example 2 except that the concentration of the zinc oxide particles (a) was changed to 5% by mass using the masterbatch of ( 2 ) above. to obtain a long fiber nonwoven fabric. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.97%, QF value 1.45, performance retention rate 0.84, a/b value in depolarization current measurement by TSC method 0.10, maximum value of depolarization after 100 ° C was 138°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
<Example 5>
The zinc oxide particles (a) had a particle diameter of 0.3 μm, and were added after preparation of a 10 % by mass masterbatch. A 6 μm long fiber nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.99%, QF value 1.48, performance maintenance rate 0.88, a/b value 0.04 in depolarization current measurement by TSC method, maximum value of depolarization after 100 ° C. The peak temperature was 140°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
＜比較例１＞
上記（３）のマスターバッチに変更した以外は、実施例２と同一とし、メルトブロー装置を用い目付１８ｇ／ｍ２、平均繊維径２．５μｍの長繊維不織布を得た。初期捕集効率９９．９５％、ＱＦ値１．２５、１００℃における性能維持率０．６８、ＴＳＣ法による脱分極電流測定におけるａ／ｂ値１．０１、１００℃以降の脱分極の最大値を示すピーク温度１３０℃であった。抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Comparative Example 1>
A long-fiber nonwoven fabric having a basis weight of 18 g/m 2 and an average fiber diameter of 2.5 μm was obtained using a meltblowing apparatus in the same manner as in Example 2 except that the masterbatch of (3) was used. Initial collection efficiency 99.95%, QF value 1.25, performance retention rate at 100 ° C. 0.68, a / b value in depolarization current measurement by TSC method 1.01, maximum value of depolarization after 100 ° C. was a peak temperature of 130°C. The antibacterial activity value was 5 or more in terms of logarithmic value for any bacterial species, which was the upper limit value for evaluation.
上記（３）のマスターバッチに変更した以外は、実施例２と同一とし、メルトブロー装置を用い目付１８ｇ／ｍ２、平均繊維径２．５μｍの長繊維不織布を得た。初期捕集効率９９．９５％、ＱＦ値１．２５、１００℃における性能維持率０．６８、ＴＳＣ法による脱分極電流測定におけるａ／ｂ値１．０１、１００℃以降の脱分極の最大値を示すピーク温度１３０℃であった。抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Comparative Example 1>
A long-fiber nonwoven fabric having a basis weight of 18 g/m 2 and an average fiber diameter of 2.5 μm was obtained using a meltblowing apparatus in the same manner as in Example 2 except that the masterbatch of (3) was used. Initial collection efficiency 99.95%, QF value 1.25, performance retention rate at 100 ° C. 0.68, a / b value in depolarization current measurement by TSC method 1.01, maximum value of depolarization after 100 ° C. was a peak temperature of 130°C. The antibacterial activity value was 5 or more in terms of logarithmic value for any bacterial species, which was the upper limit value for evaluation.
＜比較例２＞
上記（３）のマスターバッチを用い酸化亜鉛粒子（ｂ）の濃度を１質量％とした以外は比較例１と同一とし、メルトブロー装置を用い目付１８ｇ／ｍ２、平均繊維径２．７μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．８％、ＱＦ値１．０３、１００℃における性能維持率０．５８、ＴＳＣ法による脱分極電流測定でのａ／ｂ値１．８７、１００℃以降の脱分極の最大値を示すピーク温度１２８℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Comparative Example 2>
The same as Comparative Example 1 except that the masterbatch of (3) above was used and the concentration of the zinc oxide particles ( b ) was 1% by mass. A fibrous nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.8%, QF value 1.03, performance retention rate at 100 ° C. 0.58, a / b value 1.87 in depolarization current measurement by TSC method, maximum depolarization after 100 ° C. The peak temperature indicating the value was 128°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
上記（３）のマスターバッチを用い酸化亜鉛粒子（ｂ）の濃度を１質量％とした以外は比較例１と同一とし、メルトブロー装置を用い目付１８ｇ／ｍ２、平均繊維径２．７μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．８％、ＱＦ値１．０３、１００℃における性能維持率０．５８、ＴＳＣ法による脱分極電流測定でのａ／ｂ値１．８７、１００℃以降の脱分極の最大値を示すピーク温度１２８℃であった。また、抗菌活性値はいずれの菌種においても対数値で５以上となり評価上限値であった。 <Comparative Example 2>
The same as Comparative Example 1 except that the masterbatch of (3) above was used and the concentration of the zinc oxide particles ( b ) was 1% by mass. A fibrous nonwoven fabric was obtained. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.8%, QF value 1.03, performance retention rate at 100 ° C. 0.58, a / b value 1.87 in depolarization current measurement by TSC method, maximum depolarization after 100 ° C. The peak temperature indicating the value was 128°C. In addition, the antibacterial activity value was 5 or more in logarithmic value for any bacterial species, which was the upper limit value for evaluation.
＜比較例３＞
いずれの酸化亜鉛粒子も添加しなかった以外は実施例１と同一とし、メルトブロー装置を用い、目付３０ｇ／ｍ２、平均繊維径２．５μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９３％、ＱＦ値１．５３、性能維持率０．９０、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０３、１００℃以降の脱分極の最大値を示すピーク温度１４４℃であった。また、抗菌活性値はいずれの菌種においても対数値で１以下となり有効な抗菌性は得られなかった。 <Comparative Example 3>
A long-fiber nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 2.5 μm was obtained using a meltblowing apparatus in the same manner as in Example 1 except that no zinc oxide particles were added. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.993%, QF value 1.53, performance maintenance rate 0.90, a/b value 0.03 in depolarization current measurement by TSC method, maximum depolarization after 100 ° C. The peak temperature was 144°C. In addition, the antibacterial activity value was 1 or less in logarithmic value for any bacterial species, and no effective antibacterial activity was obtained.
いずれの酸化亜鉛粒子も添加しなかった以外は実施例１と同一とし、メルトブロー装置を用い、目付３０ｇ／ｍ２、平均繊維径２．５μｍの長繊維不織布を得た。これに対してエレクトレット化を実施例１と同様に行った。初期捕集効率９９．９９３％、ＱＦ値１．５３、性能維持率０．９０、ＴＳＣ法による脱分極電流測定でのａ／ｂ値０．０３、１００℃以降の脱分極の最大値を示すピーク温度１４４℃であった。また、抗菌活性値はいずれの菌種においても対数値で１以下となり有効な抗菌性は得られなかった。 <Comparative Example 3>
A long-fiber nonwoven fabric having a basis weight of 30 g/m 2 and an average fiber diameter of 2.5 μm was obtained using a meltblowing apparatus in the same manner as in Example 1 except that no zinc oxide particles were added. On the other hand, electretization was performed in the same manner as in Example 1. Initial collection efficiency 99.993%, QF value 1.53, performance maintenance rate 0.90, a/b value 0.03 in depolarization current measurement by TSC method, maximum depolarization after 100 ° C. The peak temperature was 144°C. In addition, the antibacterial activity value was 1 or less in logarithmic value for any bacterial species, and no effective antibacterial activity was obtained.
実施例１～５及び比較例１～２により、ａ／ｂ値の小さな組成においては液体荷電時フィルター性能維持率が高く、またＢ／Ａ値の小さな酸化亜鉛粒子を用いることでＱＦ値に優れ、電荷安定性指標となるａ／ｂ値が小さく、液体荷電によるエレクトレットにおいてもフィルター性能維持率が優れることがわかる。また、実施例１～５では、フィルターとしての粒子捕集効率ならびに、初期及び熱負荷後の濾材品質係数も高くエレクトレットフィルターとして優れた特性を有する。また、酸化亜鉛粒子の機能性とも両立することができる。また、本発明によると、エレクトレット化方法によらず電荷安定性に優れたエレクトレットを得ることが可能であり、コロナ放電法及び液体荷電法ともに好適に利用できることがわかる。なお、比較例３では酸化亜鉛粒子を添加しなかったため、有効な抗菌性は得られなかった。
According to Examples 1 to 5 and Comparative Examples 1 and 2, the composition with a small a/b value has a high filter performance retention rate when charged with a liquid, and the use of zinc oxide particles with a small B/A value provides an excellent QF value. , the a/b value, which is a charge stability index, is small, and the filter performance retention rate is excellent even in the electret by liquid charging. Moreover, in Examples 1 to 5, the particle collection efficiency as a filter and the quality factor of the filter medium at the initial stage and after the heat load are both high, and they have excellent properties as an electret filter. Moreover, it is compatible with the functionality of the zinc oxide particles. Moreover, according to the present invention, it is possible to obtain an electret having excellent charge stability regardless of the electretization method, and it is found that both the corona discharge method and the liquid charging method can be suitably used. In Comparative Example 3, no effective antibacterial properties were obtained because zinc oxide particles were not added.
本発明により、電荷安定性と酸化亜鉛粒子の機能性とを両立したエレクトレット及びエレクトレットフィルターを提供できるため、産業に大いに貢献できる。
According to the present invention, it is possible to provide electrets and electret filters that achieve both the charge stability and the functionality of zinc oxide particles, which can greatly contribute to industry.
Claims (7)
- ポリオレフィン樹脂に酸化亜鉛粒子を含有したエレクトレットであり、
前記酸化亜鉛粒子は、フォトルミネッセンス測定にて得られる波長３５０ｎｍ～４００ｎｍ領域におけるフォトルミネッセンス強度Ａと、波長４００ｎｍ～７００ｎｍ領域のフォトルミネッセンス強度Ｂとの比（Ｂ／Ａ）が０．１以下である、ことを特徴とするエレクトレット。 An electret containing zinc oxide particles in a polyolefin resin,
The zinc oxide particles have a ratio (B/A) of the photoluminescence intensity A in the wavelength range of 350 nm to 400 nm obtained by photoluminescence measurement to the photoluminescence intensity B in the wavelength range of 400 nm to 700 nm (B/A) is 0.1 or less. , an electret characterized by: - 含窒素化合物を含有する、ことを特徴とする請求項１に記載のエレクトレット。 The electret according to claim 1, characterized by containing a nitrogen-containing compound.
- ＴＳＣ法にて測定された５０から１００℃における脱分極電流の最大値をａ、１００℃以上における脱分極電流の最大値をｂとした場合に、ａ／ｂの値が０．３以下である、ことを特徴とする請求項１又は２に記載のエレクトレット。 The value of a/b is 0.3 or less, where a is the maximum value of the depolarization current at 50 to 100°C measured by the TSC method, and b is the maximum value of the depolarization current at 100°C or higher. 3. The electret according to claim 1 or 2, characterized by:
- 長繊維不織布である、ことを特徴とする請求項１又は２に記載のエレクトレット。 The electret according to claim 1 or 2, characterized in that it is a long fiber nonwoven fabric.
- 液体接触法により荷電されてなる、ことを特徴とする請求項１又は２に記載のエレクトレット。 The electret according to claim 1 or 2, characterized in that it is charged by a liquid contact method.
- 請求項１又は２に記載のエレクトレットを用いたことを特徴とするエレクトレットフィルター。 An electret filter characterized by using the electret according to claim 1 or 2.
- 濾材品質係数ＱＦ値が１．３ｍｍＡｑ-１以上である、ことを特徴とする請求項６に記載のエレクトレットフィルター。 7. The electret filter according to claim 6, wherein the filter medium quality factor QF value is 1.3 mmAq -1 or more.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2006249615A (en) * | 2005-03-11 | 2006-09-21 | Mitsui Chemicals Inc | Antimicrobial nonwoven fabric and its application |
| JP2016509137A (en) * | 2012-12-28 | 2016-03-24 | スリーエム イノベイティブ プロパティズ カンパニー | Electret web with charge enhancing additive |
| WO2018105546A1 (en) * | 2016-12-08 | 2018-06-14 | 東レ株式会社 | Electret fiber sheet |
| KR20190078483A (en) * | 2017-12-26 | 2019-07-04 | 롯데첨단소재(주) | Thermoplastic resin composition and article produced therefrom |
| JP2021116483A (en) * | 2020-01-23 | 2021-08-10 | 東レ株式会社 | Antibacterial nonwoven fabric as well as sanitary materials, medical articles, clothing articles and food packaging material which are produced by using antibacterial nonwoven fabric |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006249615A (en) * | 2005-03-11 | 2006-09-21 | Mitsui Chemicals Inc | Antimicrobial nonwoven fabric and its application |
| JP2016509137A (en) * | 2012-12-28 | 2016-03-24 | スリーエム イノベイティブ プロパティズ カンパニー | Electret web with charge enhancing additive |
| WO2018105546A1 (en) * | 2016-12-08 | 2018-06-14 | 東レ株式会社 | Electret fiber sheet |
| KR20190078483A (en) * | 2017-12-26 | 2019-07-04 | 롯데첨단소재(주) | Thermoplastic resin composition and article produced therefrom |
| JP2021116483A (en) * | 2020-01-23 | 2021-08-10 | 東レ株式会社 | Antibacterial nonwoven fabric as well as sanitary materials, medical articles, clothing articles and food packaging material which are produced by using antibacterial nonwoven fabric |
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