WO2022186762A1 - Continuous fibre-based aerogels from non-woven techniques - Google Patents
Continuous fibre-based aerogels from non-woven techniques Download PDFInfo
- Publication number
- WO2022186762A1 WO2022186762A1 PCT/SG2021/050106 SG2021050106W WO2022186762A1 WO 2022186762 A1 WO2022186762 A1 WO 2022186762A1 SG 2021050106 W SG2021050106 W SG 2021050106W WO 2022186762 A1 WO2022186762 A1 WO 2022186762A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fibres
- coating
- fibre web
- vinyl acetate
- aerogel
- Prior art date
Links
- 239000004964 aerogel Substances 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 31
- 239000000835 fiber Substances 0.000 title claims abstract description 29
- 238000000576 coating method Methods 0.000 claims abstract description 35
- 239000011248 coating agent Substances 0.000 claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 claims abstract description 17
- 239000000853 adhesive Substances 0.000 claims abstract description 15
- 230000001070 adhesive effect Effects 0.000 claims abstract description 15
- 239000002245 particle Substances 0.000 claims abstract description 9
- 238000003490 calendering Methods 0.000 claims abstract description 7
- 238000005507 spraying Methods 0.000 claims abstract description 6
- 239000000203 mixture Substances 0.000 claims description 21
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 20
- 239000000654 additive Substances 0.000 claims description 18
- 239000000395 magnesium oxide Substances 0.000 claims description 10
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 10
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 10
- 229920000642 polymer Polymers 0.000 claims description 10
- 238000004080 punching Methods 0.000 claims description 10
- 239000004408 titanium dioxide Substances 0.000 claims description 10
- 230000000996 additive effect Effects 0.000 claims description 9
- 229920002554 vinyl polymer Polymers 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 230000015572 biosynthetic process Effects 0.000 claims description 8
- 239000011152 fibreglass Substances 0.000 claims description 8
- 239000004111 Potassium silicate Substances 0.000 claims description 7
- 239000004115 Sodium Silicate Substances 0.000 claims description 7
- NNHHDJVEYQHLHG-UHFFFAOYSA-N potassium silicate Chemical compound [K+].[K+].[O-][Si]([O-])=O NNHHDJVEYQHLHG-UHFFFAOYSA-N 0.000 claims description 7
- 229910052913 potassium silicate Inorganic materials 0.000 claims description 7
- 235000019353 potassium silicate Nutrition 0.000 claims description 7
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 7
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 7
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 7
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 6
- 239000003063 flame retardant Substances 0.000 claims description 6
- -1 acrylic ester Chemical class 0.000 claims description 5
- DQXBYHZEEUGOBF-UHFFFAOYSA-N but-3-enoic acid;ethene Chemical compound C=C.OC(=O)CC=C DQXBYHZEEUGOBF-UHFFFAOYSA-N 0.000 claims description 5
- 239000005038 ethylene vinyl acetate Substances 0.000 claims description 5
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 claims description 5
- 229920002678 cellulose Polymers 0.000 claims description 4
- 239000001913 cellulose Substances 0.000 claims description 4
- 238000003618 dip coating Methods 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 4
- 239000000126 substance Substances 0.000 claims description 4
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 claims description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 3
- 229920002972 Acrylic fiber Polymers 0.000 claims description 3
- 229920000793 Azlon Polymers 0.000 claims description 3
- 229920000877 Melamine resin Polymers 0.000 claims description 3
- 229920002821 Modacrylic Polymers 0.000 claims description 3
- 239000004677 Nylon Substances 0.000 claims description 3
- 229920002544 Olefin fiber Polymers 0.000 claims description 3
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 3
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 3
- 229910052910 alkali metal silicate Inorganic materials 0.000 claims description 3
- 229920003235 aromatic polyamide Polymers 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 150000002148 esters Chemical class 0.000 claims description 3
- 229910021389 graphene Inorganic materials 0.000 claims description 3
- 230000002209 hydrophobic effect Effects 0.000 claims description 3
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 3
- 229920001778 nylon Polymers 0.000 claims description 3
- JMANVNJQNLATNU-UHFFFAOYSA-N oxalonitrile Chemical compound N#CC#N JMANVNJQNLATNU-UHFFFAOYSA-N 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 claims description 3
- 238000007254 oxidation reaction Methods 0.000 claims description 3
- 229920000728 polyester Polymers 0.000 claims description 3
- 229920002635 polyurethane Polymers 0.000 claims description 3
- 239000004814 polyurethane Substances 0.000 claims description 3
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 3
- 229920000131 polyvinylidene Polymers 0.000 claims description 3
- 229920001909 styrene-acrylic polymer Polymers 0.000 claims description 3
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 3
- 229920000058 polyacrylate Polymers 0.000 claims description 2
- 239000004745 nonwoven fabric Substances 0.000 abstract description 3
- 230000000704 physical effect Effects 0.000 abstract 1
- 238000005728 strengthening Methods 0.000 abstract 1
- 230000008018 melting Effects 0.000 description 9
- 238000002844 melting Methods 0.000 description 9
- 238000009413 insulation Methods 0.000 description 7
- 239000011148 porous material Substances 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 238000000352 supercritical drying Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 230000009102 absorption Effects 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000010924 continuous production Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000004108 freeze drying Methods 0.000 description 2
- 238000001879 gelation Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000003921 oil Substances 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- KKEYFWRCBNTPAC-UHFFFAOYSA-L terephthalate(2-) Chemical compound [O-]C(=O)C1=CC=C(C([O-])=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-L 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 244000198134 Agave sisalana Species 0.000 description 1
- 240000008564 Boehmeria nivea Species 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 1
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 240000000491 Corchorus aestuans Species 0.000 description 1
- 235000011777 Corchorus aestuans Nutrition 0.000 description 1
- 235000010862 Corchorus capsularis Nutrition 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 241000219146 Gossypium Species 0.000 description 1
- 240000006240 Linum usitatissimum Species 0.000 description 1
- 235000004431 Linum usitatissimum Nutrition 0.000 description 1
- 238000003483 aging Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 235000009120 camo Nutrition 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 238000009960 carding Methods 0.000 description 1
- 235000005607 chanvre indien Nutrition 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 238000012377 drug delivery Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 239000011487 hemp Substances 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229920001230 polyarylate Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000002594 sorbent Substances 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
Classifications
-
- 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
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/44—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling
- D04H1/46—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres
- D04H1/48—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres in combination with at least one other method of consolidation
- D04H1/485—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres in combination with at least one other method of consolidation in combination with weld-bonding
-
- 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
- D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
- D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
- D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
- D04H1/542—Adhesive fibres
Definitions
- the present disclosure relates to a method of manufacturing nonwoven aerogel blankets and in particular to the use of nonwoven aerogel blanket as insulative materials.
- Aerogels are some of the lightest solid materials known and are characterised by their low thermal conductivity, high porosity, low density. Since their discovery in the 1930s, the potential applications of these nanostructured solids are numerous and include heat insulations, sound absorptions, sorbents for gases such as carbon dioxide, volatile organic compounds and hazardous gases, drug delivery and as construction materials.
- the traditional aerogel fabrication process is typically manufactured in 3 distinct steps namely gelation, ageing and drying.
- precursor materials are allowed to disperse in a suitable solvent and are encouraged to gel thus transitioning to a colloidal network. This prevents shrinkage and the pores from collapsing, particularly during the drying stage.
- the gel is dried to remove the remaining liquid in a manner that minimises the surface tension of the pores of the solid network. This is typically achieved by supercritical drying or freeze-drying.
- supercritical drying the liquid within the aerogel is gasified and removed from the aerogel without crossing the liquid-gas boundary, thus eliminating the increase in surface tension that would otherwise result during evaporation which can lead to pore collapse.
- a primary embodiment of the present invention is a method of manufacturing nonwoven aerogel blanket comprising the steps of forming a fibre web comprising polymeric fibres and low melting-point polymer fibres using nonwoven web formation techniques, calendering the polymeric fibres, curing the polymeric fibres and applying a mixture comprising aerogel particles and an adhesive to the fibre web.
- the polymeric fibres are selected from a group consisting of acetate fibres, acrylic fibres, aramid fibres, azlon fibres, carbon fibres, melamine fibres, modacrylic fibres, olefin fibres, nylon fibres, poiybenzimidazoie fibres, polyacrylate fibres, polyester fibres, polyvinyl alcohol fibres, polyvinylidene fibres, polyurethane fibres, fibreglass, silica fibreglass, cellulose- based fibres or a combination thereof.
- the adhesive is selected from a group consisting of vinyl acetate, ethylene-vinyl acetate, acrylic ester, vinyl acetate-acrylic ester, styrene-acrylic ester, ethylene-vinyl acetate- vinyl ester, ethylene-vinyl acetate-acrylic ester, alkali silicates or a combination thereof
- the mixture further comprises an additive.
- the additive is thermal stable up to a temperature of about 650°C.
- the additive is selected from a group consisting of graphene oxide, carbon nitride, magnesium oxide, titanium dioxide, silicon carbide, sodium silicate, potassium silicate, magnesium oxide and titanium dioxide or a combination thereof.
- the additive is sodium silicate, potassium silicate, magnesium oxide, titanium dioxide, silicon carbide or a combination thereof.
- the mixture is applied to the fibre web by dip-coating or spraying at a pressure of 1-100 kg/cm 2 .
- the fibre web is formed is formed using needle-punching.
- the needle punching comprises a pre-needling step with a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m and a needle punching step with double-sided needling with a stroke frequency of 5 - 50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m.
- the method comprises a further step of applying a coating to the nonwoven aerogel blanket.
- the coating is selected from a group consisting of hydrophobic coating fire retardant coating, flame retardant coating, weather, and UV resistant coating, heat resistant coating, chemical resistant coating, oxidation and corrosion-resistant coating or combination thereof.
- a primary embodiment of the invention is a method of manufacturing nonwoven insulation blanket using techniques traditionally associated with the manufacture of nonwovens
- the method is preferably performed by non-woven machinery assembled in a conveyor system to allow the continuous production of aerogels.
- Polymeric fibres are fed into a fibre opening machine used in the manufacture of nonwovens that employs a fibre web formation technique. Suitable web formation techniques include dry- laid carding, air-laid and spun-laid.
- a suitable polymeric fibre generally include natural fibres or synthetic fibres such as but not limited to acetate fibres, acrylic fibres, aramid fibres, azlon fibres, carbon fibres, melamine fibres, modacrylic fibres, olefin fibres, nylon fibres, Polybenzimidazo!e fibres, polyarylate fibres, polyester fibres, polyvinyl alcohol fibres, polyvinylidene fibres, polyurethane fibres, fibreglass, silica fibreglass, cellulose based fibres or a combination thereof.
- polyethene terephthalate fibres polyethene fibres, polypropylene fibres, fibreglass, silica fibreglass, and cellulose fibres is used as the polymeric fibres.
- cellulose-based fibres can be derived from cotton, flax, hemp, jute, ramie, sisal and coir or any other fibre where cellulose is a major constituent.
- low melting point polymers are polymers that have a melting point of not more than 200°C and is lower than that of the melting point of the polymeric fibres.
- the low melting point polymer in the form of fibres is incorporated into the polymeric fibres, that is, low melting point polymeric fibres are mixed in along with the polymeric fibres and a bundle comprising low melting point polymeric fibres and polymeric fibres are present during fibre opening. These low melting point polymers will provide the bonding between the polymeric fibres after the calendering process.
- the adhesive can be applied to the fibre web at any time after the formation of the fibre web and before the calendaring step.
- suitable polymers include polyethene terephthalate, polyethene, and polypropylene. More than one low melting point polymer may be used simultaneously. The web formation process gives rise to a highly porous structure.
- the fibre web may in some embodiments be optionally thickened by being subjected to cross-lapping in order to be paved to a desired thickness.
- the fibres are bonded to create mechanical resistance between the fibres that make up the fibre web using known bonding methods employed in the manufacture of non-woven.
- the fibre web is formed by needle punching by a non-woven needle punching machine.
- needle punching involves a pre-needling step to initially tangle and create a pre-formed tension in the fibres, with a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m, depending on the fibre sources or the production rate.
- a needle punching step to form a coherent matrix and preferably involves double-sided needling with both stages having a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m, depending on the fibre sources and/or the production rate.
- other known bonding methods used in the manufacture of non-woven that may be used are stitch bonding, chemical bonding, and thermal bonding.
- the fibre web can then be subjected to a calendering process where the calendar rolls are heated to a temperature of 100°C-300°C to smoothen the surface of the aerogel before curing the fibre web at a temperature of less than 100°C-300°C to cure the crosslinks and if present, a surface coating It is understood by a person skilled in the art that the temperature used is dependent on the nature of the crosslinking/surface coating agent used.
- a mixture comprising aerogel particles and adhesives is then applied to the nonwoven insulation blanket.
- the particle size of the aerogel particles is typically in the range of 5pm - 5mm.
- Suitable adhesives include but are not limited to vinyl acetate, ethylene-vinyl acetate, acrylic ester, vinyl acetate-acrylic ester, styrene-acrylic ester, ethylene-vinyl acetate-vinyl ester, ethylene-vinyl acetate-acrylic ester, alkali silicates or a combination thereof. It would be understood by a person skilled in the art that most organic or inorganic adhesives may be suitable.
- the mixture comprises approximately 10% aerogel particles, 10% ethylene vinyl acetate, 80% water, by weight percentage.
- the mixture may be applied to the non-woven insulation blanket by spraying or dip coating.
- Adhesive used is typically available commercially as an emulsion or powder at room temperature.
- the mixture of adhesive and additives should be applied to the nonwoven insulation blanket by spraying the mixture at a pressure of 1-100 kg/cm 2 or dip-coated, depending on the viscosity of the mixture of adhesives and additives. This will ensure that the adhesive is sprayed or dip-coated to the extent that sufficiently fine mist is generated which will in turn ensure sufficient penetration of the fibre, thus ensuring that the fibres are uniformly coated.
- the mixture further comprises at least one additive or a combination thereof.
- Suitable additives include but are not limited to graphene oxide, carbon nitride, magnesium oxide, titanium dioxide, silicon carbide, sodium silicate, potassium silicate, magnesium oxide and titanium dioxide.
- the mixture composition as provided in Table 1 contains up to four additives, namely sodium silicate, potassium silicate, magnesium oxide, titanium dioxide and silicon carbide in quantities of up to 10 wt. %, depending on the target density and thermal conductivity of the nonwoven aerogel blankets.
- the mixture of adhesive and additives is applied by spraying or dip-coating onto one side, both sides, or through the nonwoven insulation blanket. This serves to strengthen the structure by forming bonds between the polymeric fibres. It would be understood that compounds with a high thermal stability, that is thermal stable at temperatures of up to approximately 650°C would be suitable for use as additives.
- Table 1 depicts a mixture composition with up to four additives as described in example 1
- a typical working example for the mixture is prepared as follows: aerogel particles (20%), ethylene-vinyl acetate (10%), and water (70%) by weight are dispersed homogeneously at
- the nonwoven aerogel blanket has a pore size of 6 nm, a density of 90 kg/m 3 , a porosity of 90%, a surface area of 400 m 2 /g, a thermal conductivity of 0 023 W/mK, a noise reduction coefficient of 050, and an oil absorption capacity of 35 g oil /g samples
- the mixture can be added with some additives such as sodium silicate, potassium silicate, magnesium oxide, titanium dioxide, and silicon carbide to increase the original product's thermal stability.
- the other characteristics of the nonwoven aerogel are also varied when adjusting the amount of aerogel particles, adhesives, and additives and will exhibit characteristics as depicted in Table 2.
- the method may include an optional step of applying a coating to the nonwoven aerogel blanket.
- coatings include the application of hydrophobic coating fire retardant coating, flame retardant coating, weather and UV resistant coating, heat resistant coating, chemical resistant coating, oxidation and corrosion-resistant coating or combination thereof. More than one coating can be applied. It is envisaged that other coatings may be applied depending on application requirements of the aerogel
- the coating includes both the application of a thin polymer coat to the surface of the aerogel or the entire internal structure including the surface of pores and junction therebetween and includes surface modification by a coating
- the application of MTMS leads to the modification of hydroxyl groups to methyl groups thus conferring hydrophobicity to the aerogel.
- the coating is applied preferably before calendaring/curing.
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- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Mechanical Engineering (AREA)
- Nonwoven Fabrics (AREA)
- Chemical Or Physical Treatment Of Fibers (AREA)
Abstract
A method of continuously manufacturing aerogel using techniques typically associated with the production of nonwoven fabrics. Polymeric fibres are arranged into a fibre web. Aerogel particles and adhesive are applied to the fibre web to strengthen the structure. Further strengthening occurs when the polymeric fibres are bonded. A spraying and coating may be applied to modify the physical properties of the aerogel depending on application requirements. The aerogel is then finished by undergoing calendaring to smoothen its surface and curing to cure the cross links and/or surface coating.
Description
CONTINUOUS FIBRE-BASED AEROGELS FROM NON-WOVEN TECHNIQUES
FIELD OF INVENTION
The present disclosure relates to a method of manufacturing nonwoven aerogel blankets and in particular to the use of nonwoven aerogel blanket as insulative materials.
BACKGROUND
Aerogels are some of the lightest solid materials known and are characterised by their low thermal conductivity, high porosity, low density. Since their discovery in the 1930s, the potential applications of these nanostructured solids are numerous and include heat insulations, sound absorptions, sorbents for gases such as carbon dioxide, volatile organic compounds and hazardous gases, drug delivery and as construction materials.
The traditional aerogel fabrication process is typically manufactured in 3 distinct steps namely gelation, ageing and drying. As its name suggests, during the gelation step, precursor materials are allowed to disperse in a suitable solvent and are encouraged to gel thus transitioning to a colloidal network. This prevents shrinkage and the pores from collapsing, particularly during the drying stage.
Lastly, the gel is dried to remove the remaining liquid in a manner that minimises the surface tension of the pores of the solid network. This is typically achieved by supercritical drying or freeze-drying. In supercritical drying, the liquid within the aerogel is gasified and removed from the aerogel without crossing the liquid-gas boundary, thus eliminating the increase in surface tension that would otherwise result during evaporation which can lead to pore collapse.
While effective, supercritical drying is not only time consuming, typically requires several days to complete but also requires specialised equipment and presents a safety hazard due to the need to operate at high pressure and temperature and accordingly is a major reason that increases manufacturing costs and poses a significant challenge when it comes to scaling up production of aerogels. While more cost-effective than supercritical drying, freeze-drying can only be done in batches, each produces at best square metres of aerogels.
Consequently, this has prevented the widespread adoption of aerogels over traditional materials in all but the most demanding applications where it would be impossible or inefficient to use a material other than an aerogel.
Hence there exists a need for a cost-effective method of manufacturing aerogels that is easiiy scalable and allows for continuous production of aerogels as opposed manufacturing in batches.
SUMMARY OF THE INVENTION
A primary embodiment of the present invention is a method of manufacturing nonwoven aerogel blanket comprising the steps of forming a fibre web comprising polymeric fibres and low melting-point polymer fibres using nonwoven web formation techniques, calendering the polymeric fibres, curing the polymeric fibres and applying a mixture comprising aerogel particles and an adhesive to the fibre web.
Optionally, the polymeric fibres are selected from a group consisting of acetate fibres, acrylic fibres, aramid fibres, azlon fibres, carbon fibres, melamine fibres, modacrylic fibres, olefin fibres, nylon fibres, poiybenzimidazoie fibres, polyacrylate fibres, polyester fibres, polyvinyl alcohol fibres, polyvinylidene fibres, polyurethane fibres, fibreglass, silica fibreglass, cellulose- based fibres or a combination thereof.
Optionally, the adhesive is selected from a group consisting of vinyl acetate, ethylene-vinyl acetate, acrylic ester, vinyl acetate-acrylic ester, styrene-acrylic ester, ethylene-vinyl acetate- vinyl ester, ethylene-vinyl acetate-acrylic ester, alkali silicates or a combination thereof
Optionally, the mixture further comprises an additive. Optionally, the additive is thermal stable up to a temperature of about 650°C. Optionally, the additive is selected from a group consisting of graphene oxide, carbon nitride, magnesium oxide, titanium dioxide, silicon carbide, sodium silicate, potassium silicate, magnesium oxide and titanium dioxide or a combination thereof. Optionally, the additive is sodium silicate, potassium silicate, magnesium oxide, titanium dioxide, silicon carbide or a combination thereof.
Optionally, the mixture is applied to the fibre web by dip-coating or spraying at a pressure of 1-100 kg/cm2.
Optionally, the fibre web is formed is formed using needle-punching. Optionally, the needle punching comprises a pre-needling step with a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m and a needle punching step with double-sided needling with a stroke frequency of 5 - 50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m.
Optionally, the method comprises a further step of applying a coating to the nonwoven aerogel blanket. Optionally, the coating is selected from a group consisting of hydrophobic coating fire retardant coating, flame retardant coating, weather, and UV resistant coating, heat resistant
coating, chemical resistant coating, oxidation and corrosion-resistant coating or combination thereof.
DETAILED DESCRIPTION OF THE INVENTION
The illustrative embodiments described in the detailed description and claims are not meant to be inclusive. Other embodiments can be utilized, and other changes can be made, without departing from the spirit or scope of the invention.
A primary embodiment of the invention is a method of manufacturing nonwoven insulation blanket using techniques traditionally associated with the manufacture of nonwovens The method is preferably performed by non-woven machinery assembled in a conveyor system to allow the continuous production of aerogels.
Polymeric fibres are fed into a fibre opening machine used in the manufacture of nonwovens that employs a fibre web formation technique. Suitable web formation techniques include dry- laid carding, air-laid and spun-laid. A suitable polymeric fibre generally include natural fibres or synthetic fibres such as but not limited to acetate fibres, acrylic fibres, aramid fibres, azlon fibres, carbon fibres, melamine fibres, modacrylic fibres, olefin fibres, nylon fibres, Polybenzimidazo!e fibres, polyarylate fibres, polyester fibres, polyvinyl alcohol fibres, polyvinylidene fibres, polyurethane fibres, fibreglass, silica fibreglass, cellulose based fibres or a combination thereof. In a preferred embodiment, polyethene terephthalate fibres, polyethene fibres, polypropylene fibres, fibreglass, silica fibreglass, and cellulose fibres is used as the polymeric fibres. In a preferred embodiment, cellulose-based fibres can be derived from cotton, flax, hemp, jute, ramie, sisal and coir or any other fibre where cellulose is a major constituent.
In addition to the polymeric fibres, at least one low melting point polymer is used in combination with the polymeric fibres to strengthen the non-woven structure. Low melting point polymers are polymers that have a melting point of not more than 200°C and is lower than that of the melting point of the polymeric fibres. The low melting point polymer in the form of fibres is incorporated into the polymeric fibres, that is, low melting point polymeric fibres are mixed in along with the polymeric fibres and a bundle comprising low melting point polymeric fibres and polymeric fibres are present during fibre opening. These low melting point polymers will provide the bonding between the polymeric fibres after the calendering process. While typically performed after the cross-lapping step, the adhesive can be applied to the fibre web at any time after the formation of the fibre web and before the calendaring step. Non-limiting examples of suitable polymers include polyethene terephthalate, polyethene, and polypropylene. More than one low melting point polymer may be used simultaneously. The web formation process gives rise to a highly porous structure.
After the formation of the fibre web, the fibre web may in some embodiments be optionally
thickened by being subjected to cross-lapping in order to be paved to a desired thickness. Next, the fibres are bonded to create mechanical resistance between the fibres that make up the fibre web using known bonding methods employed in the manufacture of non-woven. In one embodiment, the fibre web is formed by needle punching by a non-woven needle punching machine.
In the context of the present invention, needle punching involves a pre-needling step to initially tangle and create a pre-formed tension in the fibres, with a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m, depending on the fibre sources or the production rate. This is followed by a needle punching step to form a coherent matrix and preferably involves double-sided needling with both stages having a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m, depending on the fibre sources and/or the production rate. Alternatively, other known bonding methods used in the manufacture of non-woven that may be used are stitch bonding, chemical bonding, and thermal bonding.
The fibre web can then be subjected to a calendering process where the calendar rolls are heated to a temperature of 100°C-300°C to smoothen the surface of the aerogel before curing the fibre web at a temperature of less than 100°C-300°C to cure the crosslinks and if present, a surface coating It is understood by a person skilled in the art that the temperature used is dependent on the nature of the crosslinking/surface coating agent used.
A mixture comprising aerogel particles and adhesives is then applied to the nonwoven insulation blanket. The particle size of the aerogel particles is typically in the range of 5pm - 5mm. Suitable adhesives include but are not limited to vinyl acetate, ethylene-vinyl acetate, acrylic ester, vinyl acetate-acrylic ester, styrene-acrylic ester, ethylene-vinyl acetate-vinyl ester, ethylene-vinyl acetate-acrylic ester, alkali silicates or a combination thereof. It would be understood by a person skilled in the art that most organic or inorganic adhesives may be suitable. In a non-limiting example, the mixture comprises approximately 10% aerogel particles, 10% ethylene vinyl acetate, 80% water, by weight percentage. The mixture may be applied to the non-woven insulation blanket by spraying or dip coating.
Adhesive used is typically available commercially as an emulsion or powder at room temperature. The mixture of adhesive and additives should be applied to the nonwoven insulation blanket by spraying the mixture at a pressure of 1-100 kg/cm2 or dip-coated, depending on the viscosity of the mixture of adhesives and additives. This will ensure that the adhesive is sprayed or dip-coated to the extent that sufficiently fine mist is generated which will in turn ensure sufficient penetration of the fibre, thus ensuring that the fibres are uniformly coated.
In another embodiment, the mixture further comprises at least one additive or a combination thereof. Suitable additives include but are not limited to graphene oxide, carbon
nitride, magnesium oxide, titanium dioxide, silicon carbide, sodium silicate, potassium silicate, magnesium oxide and titanium dioxide. In a non-limiting example, the mixture composition as provided in Table 1 contains up to four additives, namely sodium silicate, potassium silicate, magnesium oxide, titanium dioxide and silicon carbide in quantities of up to 10 wt. %, depending on the target density and thermal conductivity of the nonwoven aerogel blankets.
Optionally, the mixture of adhesive and additives is applied by spraying or dip-coating onto one side, both sides, or through the nonwoven insulation blanket. This serves to strengthen the structure by forming bonds between the polymeric fibres. It would be understood that compounds with a high thermal stability, that is thermal stable at temperatures of up to approximately 650°C would be suitable for use as additives.
Table 1 depicts a mixture composition with up to four additives as described in example 1
It is understood that the specific fibre length or range of lengths of fibres suitable for use as understood by a person of ordinary skill in the art varies and may be dependent on both the web formation technique, bonding technique employed, along with machine manufacturer recommendations and application requirements.
Example 1
A typical working example for the mixture is prepared as follows: aerogel particles (20%), ethylene-vinyl acetate (10%), and water (70%) by weight are dispersed homogeneously at
5000 rpm for 20 minutes. The as-prepared mixture is then sprayed or dip-coated onto one
side, both sides, or through the nonwoven insulation blanket at a pressure of 50 kg/cm2 to obtain the nonwoven aerogel blanket. Within this working example, the nowoven aerogel blanket has a pore size of 6 nm, a density of 90 kg/m3, a porosity of 90%, a surface area of 400 m2/g, a thermal conductivity of 0 023 W/mK, a noise reduction coefficient of 050, and an oil absorption capacity of 35 goil/gsamples The mixture can be added with some additives such as sodium silicate, potassium silicate, magnesium oxide, titanium dioxide, and silicon carbide to increase the original product's thermal stability. The other characteristics of the nonwoven aerogel are also varied when adjusting the amount of aerogel particles, adhesives, and additives and will exhibit characteristics as depicted in Table 2.
In some embodiments, the method may include an optional step of applying a coating to the nonwoven aerogel blanket. Non-limiting examples of coatings include the application of hydrophobic coating fire retardant coating, flame retardant coating, weather and UV resistant coating, heat resistant coating, chemical resistant coating, oxidation and corrosion-resistant coating or combination thereof. More than one coating can be applied. It is envisaged that other coatings may be applied depending on application requirements of the aerogel The coating includes both the application of a thin polymer coat to the surface of the aerogel or the entire internal structure including the surface of pores and junction therebetween and includes surface modification by a coating For example, the application of MTMS leads to the modification of hydroxyl groups to methyl groups thus conferring hydrophobicity to the aerogel. The coating is applied preferably before calendaring/curing.
Claims
1. A method of manufacturing nonwoven aerogel blanket comprising the steps of: forming a fibre web comprising polymeric fibres and low melting-point polymer fibres using nonwoven web formation techniques; calendering the polymeric fibres; curing the polymeric fibres; and applying a mixture comprising aerogel particles and an adhesive to the fibre web.
2. The method according to claim 1 , wherein the polymeric fibres are selected from a group consisting of acetate fibres, acrylic fibres, aramid fibres, azlon fibres, carbon fibres, melamine fibres, modacrylic fibres, olefin fibres, nylon fibres, polybenzimidazoie fibres, polyacrylate fibres, polyester fibres, polyvinyl alcohol fibres, polyvinylidene fibres, polyurethane fibres, fibreglass, silica fibreglass, cellulose-based fibres or a combination thereof.
3. The method according to claim 1 or 2, wherein the adhesive is selected from a group consisting of vinyl acetate, ethylene-vinyl acetate, acrylic ester, vinyl acetate- acrylic ester, styrene-acrylic ester, ethylene-vinyl acetate-vinyl ester, ethylene-vinyl acetate-acrylic ester, alkali silicates or a combination thereof.
4. The method according to claim 3, wherein the mixture further comprises an additive.
5. The method according to claim 4, wherein the additive is thermal stable up to a temperature of about 650°C.
6. The method according to claim 4, wherein the additive is selected from a group consisting of graphene oxide, carbon nitride, magnesium oxide, titanium dioxide, silicon carbide, sodium silicate, potassium silicate, magnesium oxide and titanium dioxide or a combination thereof.
7. The method according to claim 6, wherein the additive is sodium silicate, potassium silicate, magnesium oxide, titanium dioxide, silicon carbide or a combination thereof.
8. The method according to any of claims 1-7, wherein the mixture is applied to the fibre web by dip-coating or spraying at a pressure of 1-100 kg/cm2.
9. The method according to claim 1, wherein the fibre web is formed is formed using needle-punching.
10. The method according to claim 9, wherein the needle punching comprises a pre needling step with a stroke frequency of 5-50 Hz, a stroke of 10-100 mm, and a needle density
of 1000-10000 s/m and a needle punching step with double-sided needling with a stroke frequency of 5 - 50 Hz, a stroke of 10-100 mm, and a needle density of 1000-10000 s/m.
11. The method according to claim 1, further comprising the step of applying a coating to the fibre web.
12. The method according to claim 11, wherein the coating is selected from a group consisting of hydrophobic coating fire retardant coating, flame retardant coating, weather, and UV resistant coating, heat resistant coating, chemical resistant coating, oxidation and corrosion- resistant coating or combination thereof.
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CN105799294A (en) * | 2016-03-11 | 2016-07-27 | 浙江理工大学 | Manufacturing method of coating composite material for automotive interior |
CN110983812A (en) * | 2020-01-13 | 2020-04-10 | 中原工学院 | Non-woven composite material with heat insulation characteristic and preparation method thereof |
US20200224005A1 (en) * | 2015-04-07 | 2020-07-16 | Lg Chem, Ltd. | Aerogel-containing composition and insulation blanket prepared using the same |
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2021
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Publication number | Priority date | Publication date | Assignee | Title |
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US20200224005A1 (en) * | 2015-04-07 | 2020-07-16 | Lg Chem, Ltd. | Aerogel-containing composition and insulation blanket prepared using the same |
CN105799294A (en) * | 2016-03-11 | 2016-07-27 | 浙江理工大学 | Manufacturing method of coating composite material for automotive interior |
CN110983812A (en) * | 2020-01-13 | 2020-04-10 | 中原工学院 | Non-woven composite material with heat insulation characteristic and preparation method thereof |
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