CN113462246B - Method for manufacturing high-performance coating for low-VOC (volatile organic compound) type screen printing - Google Patents

Method for manufacturing high-performance coating for low-VOC (volatile organic compound) type screen printing Download PDF

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CN113462246B
CN113462246B CN202110798928.9A CN202110798928A CN113462246B CN 113462246 B CN113462246 B CN 113462246B CN 202110798928 A CN202110798928 A CN 202110798928A CN 113462246 B CN113462246 B CN 113462246B
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voc
screen printing
thixotropy
dispersion
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CN113462246A (en
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赵鹏
藤田进一
吉永土佐彦
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Zhejiang Caihuang Fine Chemical Co ltd
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Zhejiang Caihuang Fine Chemical Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D133/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
    • C09D133/04—Homopolymers or copolymers of esters
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
    • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
    • C09D127/04—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
    • C09D127/06—Homopolymers or copolymers of vinyl chloride
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D163/00—Coating compositions based on epoxy resins; Coating compositions based on derivatives of epoxy resins
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D167/00—Coating compositions based on polyesters obtained by reactions forming a carboxylic ester link in the main chain; Coating compositions based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
    • C09D175/04—Polyurethanes
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/20—Diluents or solvents
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/61—Additives non-macromolecular inorganic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/70—Additives characterised by shape, e.g. fibres, flakes or microspheres

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inks, Pencil-Leads, Or Crayons (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Paints Or Removers (AREA)

Abstract

The invention provides a method for manufacturing a high-performance coating for low-VOC screen printing, which can stably obtain the required printing effects of decoration and image patterns. The method for producing a high-performance coating material for low-VOC screen printing is characterized by comprising a step of mixing and dispersing a material comprising at least a thermoplastic resin, a VOC (volatile organic solvent), an antifoaming leveling agent and a thixotropic agent (thixotropy-imparting agent), wherein the step of mixing and dispersing comprises: a dispersion production step of separately mixing and dispersing the thixotropic agent and the defoaming and leveling agent in advance to produce a thixotropy-imparting dispersion, and mixing and stirring the thixotropy-imparting dispersion with other materials.

Description

Method for manufacturing high-performance coating for low-VOC (volatile organic compound) type screen printing
Technical Field
The present invention relates to a method for producing a high-performance paint for screen printing for decoration and image pattern printing, which satisfies the national standard of the people's republic of China "GB 30981-.
Here, the thixotropy of the present invention means a ratio of a viscosity value measured at 2 revolutions per minute using a BH type rotary viscometer at a temperature of 25. + -. 1 ℃ to a viscosity value measured at 20 revolutions per minute using a BH type rotary viscometer.
Background
In recent years, it has become an important issue to reduce adverse effects of volatile organic solvents (hereinafter referred to as "VOC") on the global environment and human body. For example, with the implementation of the national standards of the people's republic of China "GB 30981-.
Under such circumstances, in the paint field, in order to satisfy the VOC content limit specified in "GB 30981-.
However, in various low VOC type coating materials, the VOC content contributing to solubility and affinity is reduced due to the decrease in the blending ratio of VOC. Further, since the viscosity of the coating material is high, if a production method similar to the conventional one is adopted, uniform dispersion of a powder material such as a thixotropic agent, which is added in a small amount in the production process, becomes insufficient. Further, in the batch printing and coating processes using the coating material, production stability is difficult to ensure.
Therefore, at present, when a problem occurs in stability in a mass production process, recovery, additional addition of VOC, re-dispersion, etc. of the coating material occur even in the production process, and such a re-adjustment process causes a serious problem of consumption of time, labor, cost, etc. more than the prior art.
Of course, the same problems as described above occur in the production process of a high-performance coating material for low VOC type screen printing, which is one of the coating materials. In particular, in order to obtain the mass stability in screen printing, that is, to obtain the desired decorative or image pattern printing effect stably at all times, it is necessary to keep the thixotropy of the coating material in an appropriate range at all times during the mass printing production.
Therefore, in order to avoid readjustment processes such as recovery of the coating material, additional addition of VOC, and redispersion during the production process, there is an increasing demand for a novel and advanced production method which is suitable for the production process of high-performance coating materials for screen printing, which can achieve sufficiently uniform dispersion of thixotropic agents, and which can always stably obtain desired decorative and image pattern printing effects even with low-VOC type coating materials.
Here, a description is given of a bad phenomenon caused in the case where thixotropy of a high-performance paint for screen printing is unstable in a batch screen printing process.
If the thixotropy is more than the appropriate range, the fluidity of the coating after printing is reduced, and due to the influence of the mesh of the screen plate itself for screen printing, jaggies are liable to be generated at the edge portion of the printed image, or the smoothness of the image surface is liable to be impaired due to insufficient leveling property.
If the thixotropy is less than a proper range, the fluidity of the coating after printing is too high, and the problems of ink overflow, distortion, plate pasting and the like are easy to occur at the edge part of a printed image.
Further, in prior patent documents 1, 2, 3 and 4, there are disclosed a material formulation and a production method for a low VOC type coating material which satisfy various resistances, characteristics and storage stability, but none of the prior documents discloses and relates to a production method for ensuring highly stable thixotropy required for a high performance coating material for low VOC type screen printing as described in the background art paragraph 5.
In particular, patent document 3 discloses that an appropriate dispersant and compounding ratio are selected and used in order to obtain stable thixotropy even during long-term storage, but when such a dispersant and compounding ratio are used, the chemical resistance and weather resistance of a coating film formed by printing or coating tend to deteriorate. In addition, since such a dispersant material is expensive and the production cost is greatly increased, there is a strong demand for the development of a technique for a production method of a high-performance coating material for low VOC type screen printing which can ensure highly stable thixotropic performance without using a dispersant which causes a large increase in cost.
Documents of the prior art
Patent literature
Patent document 1: CN110770311A (corresponding to JP Redo table 2019-022218)
Patent document 2: CN103608416A (corresponding to JP re-table 2012-176809)
Patent document 3: CN103002867A (corresponding to JP special table 2013 and 523890)
Patent document 4: CN111349361A
Disclosure of Invention
Problems to be solved by the invention
The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method for producing a high-performance coating material for low VOC type screen printing, which can avoid the readjustment process such as recovery, additional addition of VOC, and re-dispersion of the coating material during the production process, and can stably obtain the desired decorative and image pattern printing effects by maintaining the appropriate thixotropy of the low VOC type coating material, which is one of various coating materials, during the batch printing process.
Means for solving the problems
The invention relates to a method for preparing a high-performance coating for low VOC screen printing, which is characterized by comprising the working procedures of mixing, stirring and dispersing materials,
the material contains at least a thermoplastic resin, a VOC (volatile organic solvent), a defoaming leveling agent and a thixotropic agent, i.e. a thixotropy imparting agent,
the mixing and dispersing step includes:
A dispersion production step of separately mixing and dispersing the thixotropic agent and the defoaming and leveling agent in advance to produce a thixotropy-imparting dispersion, and
the thixotropy is imparted to the dispersion by mixing with other materials under agitation.
ADVANTAGEOUS EFFECTS OF INVENTION
The manufacturing method can avoid the readjustment processes of paint recovery, additional VOC addition, redispersion and the like in the production process, can always keep proper thixotropy in the batch printing process of decoration and image pattern printing production, and solves the serious problems of needing a large amount of time, labor, cost consumption and the like in the prior art.
Detailed Description
As described above, the present invention is a method for producing a high-performance coating material for low VOC screen printing, comprising the steps of mixing and dispersing materials,
the material contains at least a thermoplastic resin, a VOC (volatile organic solvent), a defoaming leveling agent and a thixotropic agent, a thixotropy-imparting agent,
the mixing and dispersing step includes:
a dispersion production step of separately mixing and dispersing the thixotropic agent and the defoaming and leveling agent in advance to produce a thixotropy-imparting dispersion, and
The thixotropy is imparted to the dispersion by mixing with other materials under agitation.
Further, the present invention is a method for producing a high-performance coating for low-VOC screen printing, wherein a blending weight ratio of the thixotropy imparting agent to the defoaming and leveling agent (blending weight of the thixotropy imparting agent/blending weight of the defoaming and leveling agent) in the thixotropy imparting dispersion is 1:3 to 3: 1.
The invention provides a method for preparing a high-performance coating for low-VOC screen printing, which is characterized in that the temperature range during mixing, stirring and dispersing in the step of preparing a dispersion body is 30-90 ℃.
The invention relates to a method for preparing a high-performance coating for low VOC type screen printing, which is characterized in that in the process of preparing a dispersion, a three-roll dispersion machine is used for dispersing for 2 times,
further, the present invention is a method for producing a high-performance low-VOC screen printing coating, wherein the thixotropy imparting agent is porous fine silica powder, and the defoaming and leveling agent is silicone oil.
Further, the invention is a method for manufacturing a high-performance coating for low-VOC screen printing, which is characterized in that relative to the high-performance coating for low-VOC screen printing, the thermoplastic resin accounts for 5-70 wt% and is one or a combination of more of acrylic resin, vinyl chloride-vinyl acetate resin, polyester resin, urethane resin, epoxy resin and melamine resin; the VOC is 20-60 wt% and the boiling point is in the range of 100-300 ℃, and is one or more of ketone solvent, ester solvent, ether solvent, aromatic hydrocarbon solvent, aliphatic hydrocarbon solvent, polyol solvent, carboxylic acid solvent; 0 to 60 wt% of the coloring pigment; 0 to 60 wt% of extender pigment, and 1 to 10 wt% of the thixotropy-imparting dispersion.
Further, the present invention is a method for producing a high-performance paint for low-VOC screen printing, characterized in that the high-performance paint or the dispersion is produced by a stirrer and a three-roll disperser each equipped with a VOC scattering prevention sealing cover having an opening/closing part, the area of the opening/closing part is 1/3 or less of the area of contact between the VOC scattering prevention sealing cover and air, and the area of the opening/closing part is 400cm2As described above.
The thermoplastic resin used in the production method of the present invention is not particularly limited, but plastics, glass, metals, and the like are often used as a material to be printed for high-performance low-VOC type screen printing paints which are widely used for decoration and image pattern printing in fields related to graphics, nameplates for display panels, electric and electronic parts, and the like. In order to maintain firm adhesion to the printing object, durability against long-term use, and weather resistance, the above-mentioned thermoplastic resin is generally selected from acrylic resins (commercially available products: DOW CHEMICAL COMPANY LIMITED/PARALOID series, Mitsubishi レイヨン ㈱/ダイヤナール series), vinyl chloride-vinyl acetate resins (commercially available products: Citsubishi Chemicals ㈱/ソルバインジリーズ, ㈱ カネカ/カネビニール series), polyester resins (commercially available products: Japanese ユピカ ㈱/ユピカ series, Baotong Jing ㈱/バイロン series), urethane resins (commercially available products: Baotong Jing ㈱/バイロン UR series, DIC バイエルポリマー ㈱/PANDEX series), epoxy resins (commercially available products: Sanjing CHEMICAL strain/エポキー series, Mitsui CHEMICAL strain, Mitsubishi 8925/3832 series), polyvinyl alcohol-type resins, polyvinyl alcohol type resins, and the like, Mitsubishi ケミカル ㈱/jER series), melamine resin (commercially available example: showa electric engineering マテリアルズ ㈱/メラン series, and three wells サイテック ㈱/サイメル series).
The weight average molecular weight of the thermoplastic resin is preferably 4,000 to 200,000, more preferably 6,000 to 150,000, and still more preferably 8,000 to 100,000.
If the weight average molecular weight of the thermoplastic resin is less than 4,000, the high-performance coating film for low-VOC screen printing tends to have problems such as poor chemical resistance and weather resistance.
On the other hand, if the weight average molecular weight of the thermoplastic resin exceeds 200,000, the solubility in VOC is deteriorated, a large amount of VOC is required to dissolve the thermoplastic resin, and the difficulty of manufacturing a high-performance coating material for low-VOC type screen printing by controlling the VOC content is greatly increased.
In addition, the weight percentage content of the thermoplastic resin in the high-performance coating for low-VOC screen printing is preferably 5 to 70 wt%, more preferably 7 to 60 wt%, and even more preferably 10 to 50 wt%.
If the content of the thermoplastic resin is less than 5 wt%, the high-performance coating film for low VOC screen printing has poor chemical resistance and weather resistance, and poor adhesion to a printed material.
On the other hand, if the content of the thermoplastic resin exceeds 70 wt%, the viscosity of the high-performance paint for low VOC screen printing becomes extremely high, and the paint is no longer suitable for the printing method of screen printing.
The VOC used in the production method of the present invention is not particularly limited, but from the viewpoint of the solubility of the thermoplastic resin and the flow stability on the printing screen required in the high-performance low-VOC screen printing coating, it is preferable that the high-performance low-VOC screen printing coating has a boiling point in the range of 100 to 300 ℃, and the high-performance low-VOC screen printing coating contains 20 to 60 wt% of one or more of a ketone solvent, an ester solvent, an ether solvent, an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, a polyol solvent, and a carboxylic acid solvent (trade name, for example, DBE).
The boiling point of the VOC is preferably 120 to 270 ℃, and more preferably 140 to 250 ℃.
In addition, the weight percentage of the VOC is preferably 22 to 55 wt%, and more preferably 25 to 50 wt%.
If the VOC boiling point is less than 100 ℃, the drying and volatilization speed of the high-performance coating for low-VOC screen printing is too high in the screen printing process, so that the bad phenomenon that the batch printing stability is influenced is generated.
On the other hand, if the VOC boiling point is greater than 300 ℃, the drying and volatilization speed of the high-performance coating for low-VOC screen printing is extremely slow during the screen printing process, and further, the adverse phenomena of excessive heat and excessively long time required for drying the coating film occur.
If the weight percentage of the VOC in the high-performance coating is less than 20 wt%, the thermoplastic resin is not sufficiently dissolved, or the viscosity of the low-VOC type high-performance coating for screen printing is too high, so that poor screen printability occurs.
On the other hand, if the weight percentage of the VOC in the high-performance paint is more than 60 wt%, the VOC content limit value in the national standard GB 30981-2020 (hazardous substance limit in industrial protective paint) of the people's republic of China is not met.
Specific examples of VOCs used in the production method of the present invention include: butyl cellosolve acetate, a mixed solvent containing dialkyl adipate ester (a commercially available product such as Flexisolv DBE as a carboxylic acid-based solvent), isophorone, 3-methoxy-3-methylbutanol, 3-methoxy-3-methylbutyl acetate, coal tar naphtha (coal-tar naptha) having a boiling point of more than 170 ℃, diethylene glycol monoethyl ether (acetate), diethylene glycol monobutyl ether, triethylene glycol monobutyl ether (acetate), cyclohexanone, coal tar naphtha having a boiling point of 160 to 170 ℃, mineral spirit having a boiling point of 150 to 170 ℃, 1-methoxy-2-propanol, 1-methoxypropyl-2-acetate, diacetone alcohol, and the like.
In the production method of the present invention, the content of the coloring pigment and/or the extender pigment in the high-performance low-VOC screen printing coating material is not particularly limited as long as the content is in the range of 0 to 60 wt%, and the pigment can be dispersed by a dispersing machine such as a three-roll dispersing machine without causing troubles such as clogging of a screen printing plate. The weight percentage of the mixed amount of the coloring pigment or/and the extender pigment in the high-performance coating for low VOC type screen printing is preferably 0-60 wt%, more preferably 0-55 wt%, and even more preferably 0-50 wt%.
In addition, the color pigments are aimed at obtaining the desired coloring properties, while the extender pigments are used to adjust high-performance coatings to the appropriate flow properties and to partially replace the generally expensive color pigments.
When the colorless and transparent high-performance coating for low-VOC screen printing is manufactured, the colorless and transparent performance of the high-performance coating can be ensured by adjusting the weight percentage of the coloring pigment or/and the extender pigment in the high-performance coating for low-VOC screen printing to be 0%.
On the other hand, if the weight percentage of the coloring pigment and/or the extender pigment in the high-performance coating for low VOC type screen printing exceeds 60 wt%, the dispersion by the dispersion machine becomes difficult to be uniform with the increase of the solid content, and the printing by the screen printing method becomes difficult.
Examples of the colored pigment include:
azo pigments, disazo pigments, phthalocyanine pigments, anthraquinone pigments, isoindoline pigments, disazo pigments, and azo pigments
Figure BDA0003163901500000081
An oxazine pigment, a quinacridone pigment, a perylene pigment, a carbon black pigment, a lake black pigment, a perylene black pigment, an aniline black pigment, an iron oxide pigment, a titanium pigment, a zinc sulfide pigment, and the like.
One or more of the above pigments may be used in combination, and in addition, if necessary, various colored dyes may be used for coloring.
Examples of the extender pigment include:
silica, talc, calcium carbonate, magnesium carbonate, bentonite, precipitated barium sulfate, zinc oxide, alumina, and the like, and one or more of the above pigments may be used in combination.
Further, in the production method of the present invention, it is also possible to use a filler such as resin beads, metal particles, metal powder, metal oxide powder, graphite, pearl pigment, fluorescent pigment, wax particles, protein powder, etc., and a functional material such as an ultraviolet absorbing material, an antibacterial material, a heat absorbing material, a refractive index adjusting material, a slip-increasing material, an anti-slip material, a light-storing material, a polarizing material, an antireflection material, a diffusible material, etc. in combination. For the same reason as described above, the amount of the high-performance coating material for low VOC screen printing may be suitably in the range of 0 to 60 wt%, more preferably 0 to 55 wt%, and still more preferably 0 to 50 wt%.
The production method of the present invention is different from the conventionally employed production method, though it is necessary to contain an antifoaming leveling agent and a thixotropic agent. In the conventional method, the defoaming and leveling agent and the thixotropic agent are separately metered and added in sequence together with other materials, mixed and stirred, and then dispersed. The method for producing a low-VOC screen printing paint of the present invention is characterized in that a thixotropy imparting dispersion material is produced by separately mixing and dispersing a thixotropic agent and a defoaming leveling agent in advance, and then the thixotropy imparting dispersion material is weighed and charged, and is mixed with other materials and stirred, and then dispersed.
The present inventors have found that by using such a thixotropy-imparting dispersion found by a new concept in a production process of a high-performance coating material for low-VOC screen printing, it is possible to easily ensure that a thixotropic agent is in a uniformly dispersed state in the high-performance coating material for low-VOC screen printing. Further, the readjustment processes of paint recovery, additional VOC addition, redispersion and the like in the production process are avoided, proper thixotropy can be always kept in the batch printing process of decoration and image pattern printing production, and the serious problems of large time consumption, labor force, cost and the like in the prior art are solved.
Further, the same problems as described in paragraphs 7 to 9 of the background art are caused by unstable thixotropy due to insufficient dispersion of the thixotropic agent and further by the occurrence of defects in the mass printing production process.
Here, the reason why the thixotropy-imparting dispersion is produced by the thixotropic agent and the defoaming leveling agent is selected is explained as follows:
the high-performance coating for low-VOC screen printing at least comprises thermoplastic resin, VOC, a defoaming and leveling agent and a thixotropic agent. However, since the thermoplastic resin is solid, it is not easy to uniformly mix and stir and uniformly disperse the thermoplastic resin with the thixotropic agent. The same applies to other solid materials such as coloring pigments, extender pigments, fillers and the like applied to high-performance coating for low VOC type screen printing.
In addition, since VOC has extremely low viscosity, it is difficult to perform dispersion with a dispersion machine, and further, in the production process of the dispersion material for imparting thixotropy, there arises a problem that VOC partially volatilizes.
Further, it is also considered to add a thixotropic agent to a resin varnish prepared by dispersing and dissolving a thermoplastic resin in VOC, but VOC is partially volatilized during the varnish manufacturing process, and further, the types of thermoplastic resin and VOC used are various depending on the type of high performance coating material for low VOC type screen printing, and further, the viscosity of the resin varnish is also different, so that it is necessary to prepare many types of thixotropic agent dispersions, which seriously affects the manufacturing production efficiency.
In view of the above circumstances, the present inventors have made extensive studies and experiments to find that it is an optimum means to produce a thixotropy-imparting dispersion by mixing with an antifoaming leveling agent which contains little VOC, has a low viscosity and has an appropriate viscosity, and is commonly used in many types of high-performance coating materials for low-VOC screen printing.
In the thixotropy-imparting dispersion in the production method of the present invention, the blending weight ratio of the thixotropic agent to the defoaming leveling agent (the blending weight of the thixotropic agent/the blending weight of the defoaming leveling agent) is preferably 1:3 to 3:1, more preferably 1:2 to 3:1, and still more preferably 1:1 to 3: 1.
If the blending weight ratio of the thixotropic agent to the defoaming and leveling agent is less than 1:3 and the blending ratio of the thixotropic agent is small, the content of the defoaming and leveling agent in the high-performance coating for low-VOC screen printing manufactured by using the thixotropy imparting dispersion with the corresponding blending ratio is too high, which may cause poor adhesion performance between the high-performance coating film for low-VOC screen printing and the printed object.
On the other hand, if the mixing weight ratio of the thixotropic agent and the defoaming leveling agent is more than 3:1 and the mixing ratio of the defoaming leveling agent is small, the viscosity at the time of producing the dispersion to be imparted with thixotropy becomes too high, and the production thereof becomes difficult.
The temperature for mixing, stirring and dispersing during the preparation of the dispersion for imparting thixotropy is preferably within the range of 30-90 ℃, more preferably 35-75 ℃, and even more preferably 40-60 ℃, and the dispersion is carried out twice by a three-roll dispersing machine in the process.
If the temperature is less than 30 ℃, the aggregation of the thixotropic agent cannot be sufficiently released (sufficient dispersion cannot be performed), or more time is required for dispersion mixing.
On the other hand, if the temperature is higher than 90 ℃, a trace amount of high-boiling-point solvent and lubricant contained in the defoaming and leveling agent volatilize, and the defoaming and leveling effect is reduced.
In the mixing and stirring step in the production process of the thixotropy-imparting dispersion, a blade mixer or a vibration mixer is usually used, and the mixing and stirring are usually carried out for about 15 to 60 minutes under an appropriate shearing condition.
On the other hand, in the dispersing process, a dispersing machine such as a bead mill or a three-roll dispersing machine can be usually used, but according to experimental studies by the present inventors, it has been proved that the use of a three-roll dispersing machine is more suitable.
The reason for this is not clear, but is presumably because the principle of dispersion such as breaking stress and shear stress inherent in a three-roll dispersing machine improves the wettability of the thixotropic agent and the defoaming leveling agent, and inhibits the re-aggregation of the thixotropic agent.
The above description describes a suitable apparatus for mixing, stirring and dispersing the thixotropy-imparting dispersion, which is also applicable to the production process of high performance coating materials for low VOC type screen printing.
As the thixotropic agent described in the production method of the present invention, there may be mentioned, for example, clays (commercially available products: ELEMENTIS SPECIALTIES/ベントン series, クニミネ chemical ㈱/クニピア series), silicas (commercially available products: Fuji シリシア chemical ㈱/サイリシア series, Japanese アエロジル ㈱/アエロジル series) and the like. In order to obtain the desired thixotropic properties by adding the amount of the silica particles as small as possible, the porous particulate silica powder preferably has an average particle diameter of 4 to 100nm, more preferably 7 to 70nm, and still more preferably 10 to 50 nm.
If the average particle diameter of the porous particulate silica powder is less than 4nm, it becomes difficult to sufficiently disperse the porous particulate silica powder by a three-roll disperser. When the average particle diameter of the porous particulate silica powder exceeds 100nm, the effect of imparting thixotropy is reduced, and transparency, surface gloss and the like of a high-performance coating film for low-VOC screen printing are adversely affected.
Examples of the antifoaming and leveling agent used in the production process of the present invention include silicone oils, silicone derivatives (commercially available products: concession chemical ㈱/KF, KS series, ビックケミー. ジャパン ㈱/BYK series), fluorine-based surfactants, high-molecular acrylic polymer derivatives, and high-boiling polyether compounds (AGC セ イ ミ ケミカル ㈱/サーフロン series, Eiken chemical ㈱/フローレン series). In order to obtain good defoaming effect and leveling property by adding as small amount as possible and to be generally applicable to various low VOC type high-performance coating materials for screen printing, silicone oil with the viscosity of 500-10,000 cps (centipoise) is preferred, the viscosity is more preferably 700-7,000 cps, and the viscosity is still more preferably 1,000-3,000 cps.
If the viscosity of the defoaming leveling agent is less than 500cps, dispersion with the thixotropic agent becomes difficult because the viscosity is too small, and it becomes difficult to obtain a desired defoaming leveling effect when added in a small amount. On the other hand, if the viscosity is more than 10,000cps, the viscosity becomes too high, and it becomes extremely difficult to produce a thixotropy-imparting dispersion in which the blending weight ratio of the thixotropic agent to the defoaming leveling agent is 1:3 to 3: 1.
The weight percentage of the thixotropic property-imparting dispersion in the low-VOC high-performance coating for screen printing is preferably 1 to 10 wt%, more preferably 2 to 8 wt%, and still more preferably 3 to 6 wt%.
In addition, the following description is incorporated by reference.
As described above, the blending weight ratio of the thixotropic agent to the defoaming leveling agent in the thixotropy-imparting dispersion is preferably in the range of 1:3 to 3:1, and the weight percentage of the thixotropy-imparting dispersion material in the high-performance coating for low-VOC type screen printing is preferably 1 to 10 wt%. And sequentially calculating the addition ratio of the thixotropic agent monomer in the high-performance coating for low-VOC screen printing, which accounts for 0.25-7.5 wt%, and the addition ratio of the defoaming and leveling agent monomer is also 0.25-7.5 wt%.
If the thixotropy-imparting dispersion is added in an amount of less than 1% by weight in the high-performance coating for low VOC type screen printing, the amount of addition of the thixotropic agent monomer is too small (less than 0.25% by weight) to obtain desired thixotropy. On the other hand, if it exceeds 10 wt%, the amount of the defoaming and leveling agent monomer added is too large (exceeds 7.5 wt%), and poor adhesion between the coating layer and the object to be printed tends to occur.
In addition, the inventors of the present invention have confirmed through repeated experimental studies that: in the production method of the present invention, the high-performance coating material for low-VOC screen printing and the thixotropy-imparting dispersion material are produced by a stirrer and a three-roll disperser each equipped with a VOC scattering prevention sealing cover having an opening/closing part having an area equal to or smaller than 1/3 and equal to or smaller than 400cm in the area where the sealing cover is in contact with air, and the area being equal to or smaller than 400cm in the area where the sealing cover is in contact with air, and the high-performance coating material for low-VOC screen printing and the three-roll disperser can be produced more stably with high quality2The above.
If the area of the opening/closing portion exceeds 1/3, which is the area of the sealing lid in contact with the air, the volatile amount of VOC in the high-performance paint for low-VOC screen printing and the thixotropy-imparting dispersion exceeds 0.5 wt% of the whole amount, which causes a problem of VOC environmental emission and has a subtle influence on thixotropy, flow characteristics, and the like of the high-performance paint for low-VOC screen printing.
On the other hand, if the area of the opening/closing part is less than 400cm2In this case, it is difficult to additionally input various additives required in the process, and to perform operations such as sampling a small amount of sample during the inspection and returning the inspection sample.
The shape of the opening/closing portion is preferably an appropriate shape that can be easily worked by an operator, such as a square-like shape, a circular-like shape, or a semicircular-like shape. Further, the opening and closing mechanism of the opening and closing section is of a folding type or a sliding type, and there is no particular problem.
Examples
Examples of the present invention and comparative examples are shown in [ table 1] and [ table 2] below. The present invention is not limited to the examples.
[ Table 1]
Figure BDA0003163901500000131
[ Table 2]
Figure BDA0003163901500000141
First, the thixotropy-imparting dispersion described in the present invention is produced as follows.
The thixotropic agent and the defoaming and leveling agent described in tables 1 and 2 were mixed and stirred uniformly by a blade mixer, and then uniformly dispersed by a three-roll disperser 2 times.
Here, the mixing ratio of the thixotropic agent and the defoaming and leveling agent, the production temperature, whether or not the stirrer or the three-roll disperser equipped with the VOC scattering prevention sealing lid was used, and the like were carried out as shown in tables 1 and 2.
Next, the production of the high-performance low-VOC screen printing coating material according to the present invention is performed as follows.
The materials specified in tables 1 and 2 were mixed and stirred uniformly by a blade mixer, and then uniformly dispersed 2 times by a three-roll disperser.
Here, the mixing ratio of the respective materials, whether or not the stirrer and the three-roll disperser each equipped with the VOC scattering prevention sealing cover were used, and the like were carried out as shown in tables 1 and 2. The sealing lid of the blade mixer was used to seal an opening having a diameter of 1m (area of 7,850 cm) 2) The lid for sealing a cylindrical stirring vessel of (4) is provided with an area of 2,512cm2The semicircular opening and closing part of (1); the closed cover of the three-roller disperser is used for dispersing the liquid with the area of 20,000cm2A cover for sealing the rectangular opening part, the cover having an area of 6,000cm2The rectangular opening/closing section.
In addition, the examples are examples in which the thixotropy-imparting dispersion described in the present invention is used, and the comparative examples are examples in which a thixotropic agent and a defoaming leveling agent are separately compounded.
Further, the thixotropy index (value of thixotropy) of the high-performance coating material for low VOC type screen printing is calculated by the following method.
That is, the low VOC type wire mesh high performance coating material immediately after the 20 th sheet, 500 th sheet, 1,000 th sheet, and 2,000 th sheet was sampled and measured for viscosity values at 2 rpm and 20 rpm using a BH type tachometer at a temperature of 25 ± 1 ℃, and calculated according to the formula "viscosity value at 2 rpm/viscosity value at 20 rpm" which is thixotropy index ".
In order to maintain the stability in mass production, it is generally required that the thixotropy index in mass printing production has a variation value of 10% or less from the thixotropy index immediately before production (before use in mass printing).
Further, the printing conditions for mass production of the high performance coating for low VOC screen printing are as follows.
High-performance coating materials for low-VOC type screen printing were used as examples and comparative examples;
a 360-mesh screen plate with the diameter of 25 mu m is used, the screen used by the screen plate is the screen with the thickness of 29 mu m and the opening rate of 42 percent which are subjected to calendaring processing, the emulsion thickness of the screen plate is 15 mu m, and the emulsion surface is processed smoothly;
printing was performed using the print target described in tables 1 and 2.
The screen printing conditions at this time were: the scraping glue hardness is 80 degrees (the material is carbamate), the screen gap is 5mm, the scraping glue printing is to press the screen into the screen by 1.5mm, the scraping glue angle is 75 degrees, the scraping glue speed is 150 mm/s, and the ink return knife pressure is to press the screen by 1.5 mm.
In addition, as the pattern design of the screen printing plate, at least a square pattern with a side length of 100mm or more is required, and a thin line pattern with a width of not less than 100 μm is required in both horizontal and vertical directions of the printing direction.
The evaluation of the quality of the printed matter in the mass production printing was performed by the following method.
The printed matters of 20 th, 500 th, 1,000 th and 2,000 th sheets from the start of batch printing were compared with the printed matter of 2 nd sheet from the start of batch printing, and the image change, stability and the like of the printed matters were evaluated in the "excellent, good" and "Δ" manner described below. The reason why the printed matter on the 1 st sheet from the start of mass production was not evaluated comparatively is because the printed matter on the 1 st sheet was likely to have a defective printed image due to poor wettability between the screen plate and the coating material in the case of screen printing.
The quality of the printed image was evaluated using the fineness of the 100 μm longitudinal thin line pattern (presence or absence of chipping, bleeding, breaking, deformation, jaggy, etc.) and the surface smoothness of a square pattern with a side length of 100mm (presence or absence of unevenness, roughness, presence or absence of a screen mark, etc.).
Excellent: the observation was performed using a magnifying glass of 8 magnifications, and the fine lines and the square patterns were of the same quality as compared with the 2 nd printed matter.
Good component: visual observation showed that there was no significant difference between the fine line and the square pattern as compared with the 2 nd printed matter.
And (delta): as a result of visual observation, a subtle defect phenomenon occurred in one of the thin lines and the square pattern as compared with the 2 nd printed matter.
X: as a result of visual observation, it was easily confirmed that a defect phenomenon occurred in both the thin lines and the square pattern as compared with the 2 nd printed matter.
As is clear from tables 1 and 2, by using the production method of the thixotropy-imparting dispersion described in the present invention, the stability of the thixotropy performance in the use of the high-performance coating material for low-VOC screen printing in the mass printing can be relatively easily improved and realized, the time, labor and cost consumption in the use process are not greatly increased, and the stability of the quality of the printed matter in the mass printing can be effectively ensured.

Claims (4)

1. A method for producing a high-performance coating for low VOC screen printing, which is characterized by comprising a step of mixing and dispersing materials,
the material at least comprises a thermoplastic resin, a VOC (volatile organic solvent), a defoaming and leveling agent and a thixotropic agent, namely a thixotropy-imparting agent,
the mixing and dispersing step includes:
a dispersion production step of separately mixing and stirring and dispersing the thixotropic agent and the defoaming and leveling agent in advance to produce a thixotropy-imparting dispersion, and
the thixotropy-imparting dispersion is mixed with other materials under stirring,
in the thixotropy imparting dispersion, the mixing weight ratio of the thixotropic agent to the defoaming and leveling agent is 1: 3-3: 1,
in the thixotropy-imparting dispersion, the thixotropy-imparting agent is porous fine-particle silica powder, the defoaming and leveling agent is silicone oil,
the thermoplastic resin is 5-70 wt% relative to the total weight of the high-performance coating for low-VOC screen printing, and is one or more of acrylic resin, vinyl chloride-vinyl acetate resin, namely vinyl chloride-vinyl acetate copolymer resin, polyester resin, urethane resin, epoxy resin and melamine resin; the VOC is 20-60 wt%, the boiling point is 100-300 ℃, and the VOC is one or a combination of more of ketone solvents, ester solvents, ether solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, polyol solvents and carboxylic acid solvents; 0 to 60 wt% of a coloring pigment, 0 to 60 wt% of an extender pigment, and 1 to 10 wt% of a thixotropy imparting dispersion.
2. The method for producing a high-performance low-VOC coating for screen printing according to claim 1, wherein the temperature during mixing and dispersing in the step of producing the dispersion is in the range of 30 to 90 ℃.
3. The method for producing a high-performance coating material for low-VOC screen printing according to claim 1, wherein the dispersion in the step of producing the dispersion is carried out 2 times by a three-roll disperser.
4. The method for producing a high-performance low-VOC paint for screen printing according to any of claims 1 to 3, characterized in that the paint is produced by a stirrer and a three-roll disperser each equipped with a VOC-scattering prevention sealing cover having an opening/closing part, and the area of the opening/closing part is 400cm or less and is equal to or less than 1/3, which is the area where the sealing cover contacts with air2As described above.
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