JPS6259747B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention coats the surface of a base material such as building window glass, vehicle glass, eyeglass lens, optical lens, goggle, mirror, etc. made of glass or transparent plastic molding, and generates water vapor by condensation etc. The present invention relates to a resin composition for antifogging coating that prevents fogging. More specifically, the present invention comprises, as component A, a polymer obtained by copolymerizing a specific lower alkyl acrylate or/and lower alkyl methacrylate and a specific hydroxy lower alkyl acrylate or/and hydroxy lower alkyl methacrylate in a specific range amount; component B; A condensation esterification polymer of a specified polyether and acrylic acid or its copolymer and/or methacrylic acid or its copolymer; and a specified amount of a specified methylolmelamine as component C; The present invention relates to a resin composition for antifogging coating that has excellent properties, adhesiveness, abrasion resistance, and stain resistance. Conventionally, some methods have been used to make the substrate surface antifogging by coating it with a hygroscopic resin such as hydrophilic acrylate or methacrylate polymer, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, or hydroxyethyl cellulose. , defects such as poor water resistance and peeling from the base material, and poor abrasion resistance and easy scratching are inevitable. To improve abrasion resistance, a hygroscopic resin coating is formed on the base material to form a lower layer film, and then a melamine, urea, alkyd resin, etc. that imparts abrasion resistance is added to the lower layer. Patent Publication No. 52-22644 published a multi-layered anti-fog coating film with an upper layer of resin with high surface hardness and a hydrophilic surfactant that imparts anti-fog properties.
However, the lower layer film has poor water resistance and adhesion defects, and the upper layer film inevitably becomes sticky due to leaching of hydrophilic surfactants, resulting in stains and defects over time. There is a defect that the anti-fogging property is deteriorated. In order to solve the above-mentioned conventional problems, the present inventors have developed a product with excellent anti-fogging properties, transparency, adhesion, abrasion resistance, and stain resistance that exhibit long-lasting properties even without the use of hydrophilic surfactants. Various studies were conducted on various resins in order to provide a resin composition for antifogging coatings that share the same properties. As a result, as a component of the coating resin composition, a polymer prepared by copolymerizing a specific lower alkyl acrylate or/and lower alkyl methacrylate and a specific hydroxy lower alkyl acrylate or/and hydroxy lower alkyl methacrylate in a specific range amount under specific conditions. The combined A component has poor compatibility with resins other than the specific methylol melamine (component C), such as etherified methylol urea resin, etherified urea melamine cocondensate, etc., and may cause whitening, rough skin, or cissing. occurs and the coating film is not smooth. However, it has excellent compatibility with a specific methylolmelamine (component C), and when coating a substrate with this coating resin composition, the antifogging properties of the coating film are insufficient, but it has excellent transparency and smoothness. It has been found that the coating film has excellent adhesion and abrasion resistance. Further, as a result of various studies, the present inventors have found that when a specific amount of a condensation ester polymer of a specific polyether and acrylic acid or a copolymer thereof and/or methacrylic acid or a copolymer thereof is used in combination as component B, The inventors made the surprising discovery that the antifogging properties can be significantly improved without impairing the transparency, adhesion, and abrasion resistance of components A and C, leading to the completion of the present invention. That is, the present invention provides a resin composition for antifogging coating, wherein (a) component A has the general formula () (In the formula, R ₁ is H or CH ₃ , R ₂ is 1 carbon number
〜8 alkyl groups), and a repeating unit represented by the general formula (), (In the formula, R ₃ is H or CH ₃ , R ₄ is 1 carbon number
80% by weight of the repeating unit represented by ~6 alkylene groups) in the polymer.
It is a polymer containing the above, and has a number average molecular weight of 500 to 10,000 and a hydroxyl value of 80 to 450, and (b) component B has the general formula () (In the formula, R ₅ is H or CH ₃ , R ₆ is H or
CH ₃ , m is an integer of 1 to 20, n is an integer of 5 to 20), and (c) the C component has about 3 or more methoxymethyl groups per triazine ring. It is methylolmelamine, (d) the total amount of component A and component B is 50 to 90% by weight, and
An anti-fogging coating characterized in that the component is 50 to 10% by weight, and the blending ratio of component A and component B is 30 to 70 parts by weight of component A and 70 to 30 parts by weight of component B. To provide a resin composition. Constituting the antifogging coating resin composition of the present invention,
General formula () used for the above A component

The compound of the repeating unit represented by [Formula] is a compound in which R ₁ represents H or CH ₃ and R ₂ represents a linear or branched alkyl group having 1 to 8 carbon atoms; Examples of the compound include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, bentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, Examples include butyl methacrylate, bentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, and arbitrary mixtures thereof. In addition, the general formula () used for the above A component In the compound with a repeating unit represented by, R ₃ is H
or CH ₃ and R ₄ is a linear or branched alkylene group having 1 to 6 carbon atoms. Examples of these compounds include hydroxymethyl ester, hydroxyethyl ester, and hydroxyl ester of acrylic acid. Examples include propyl ester, hydroxybutyl ester, hydroxybentyl ester and hydroxyhexyl ester, hydroxymethyl ester and hydroxyhexyl ester of methacrylic acid, and any mixtures thereof. Component A of the present invention contains a compound having a repeating unit represented by the general formula () and the general formula () in an amount of 80% by weight or more, preferably 90% by weight in the polymer as a repeating unit.
Other compounds to be copolymerized include, but are not particularly limited to, styrene, d-methylstyrene, methacrylamide, N-methylolmethacrylamide, acrylamide, diallyl phthalate, allyl glycidyl ether, Examples include glycidyl methacrylate, 2-ethylhexyl glycidyl ether, vinyl acetate, acrylonitrile, vinyl propionate, and the like. The proportion of these compounds to be used in the copolymerization is determined appropriately so that the number average molecular weight of component A obtained in the copolymerization is in the range of 500 to 10,000, and in particular, the hydroxyl value is in the range of 80 to 450. The polymer can be produced by any copolymerization method commonly known in the art, such as bulk copolymerization, suspension copolymerization, emulsion copolymerization, and solution copolymerization under normal pressure or under pressure. Copolymerization can be carried out by the usual radical copolymerization method or ionic copolymerization method. However, solution copolymerization and bulk copolymerization are preferred because they tend to yield relatively small number average molecular weights of 500 to 10,000. The number average molecular weight of component A of the present invention is measured by GPC method (Gel-permeation chromatography), and the value needs to be 500 to 10,000. If the number average molecular weight is less than 500, the resulting coating film will not only be highly sticky and have insufficient stain resistance, but also will not have a hardness that can be put to practical use and will have insufficient abrasion resistance. Furthermore, when the number average molecular weight exceeds 10,000, the coating film becomes too hard and brittle. In view of wear resistance, stain resistance, etc., the number average molecular weight is preferably 700 to 5000. In addition, the hydroxyl value of component A of the present invention is 80 to 450.
preferably in the range of 100 to 400,
100-300 is particularly preferred. The hydroxyl value here refers to mg of potassium hydroxide required to neutralize acetic acid bound to an acetylated product obtained from 1 g of sample.
It is determined by the pyridine acetic anhydride method. When the hydroxyl value of the component A of the present invention is less than 80, the coating film becomes sticky, has insufficient hardness, and has significantly poor antifogging properties. Furthermore, if the hydroxyl value exceeds 450, the coating film will be hard and brittle with poor adhesion to the substrate. The above B component constituting the resin composition for antifogging coating of the present invention has the general formula () In the polymer represented by R ₅ is H or CH ₃ , R ₆
is H or CH ₃ , m is an integer of 1 to 20, n is 5 to 20
These include polyethers of polyethylene glycol and/or propylene glycol, where n is an integer of 5 to 20, and acrylic acid or its copolymer, where m is an integer of 1 to 20. Or/and ester compounds with methacrylic acid or copolymers thereof, and arbitrary mixtures thereof. When n is less than 5, anti-fog properties, stain resistance due to stickiness, and abrasion resistance due to decreased hardness will be insufficient.
When n exceeds 20, compatibility decreases, and transparency and adhesion deteriorate due to rough skin, whitening, etc. Also,
When m exceeds 20, transparency and adhesion deteriorate due to decreased compatibility. In order to obtain an excellent antifogging coating resin composition that simultaneously satisfies these antifogging properties, transparency, adhesion, and abrasion resistance, m in component B must be an integer of 1 to 20, and n be 10 to 15. Integer numbers are particularly preferred. Methylolmelamine having about 3 or more methoxymethyl groups per triazine ring, which is component C of the present invention, is an average of 6 hydrogen atoms of the 3 amino groups (-NH ₂ ) present in the triazine ring. and three or more hydrogen atoms may be substituted with methoxymethyl groups, and the other hydrogen atoms may be as they are or may be substituted with methylol groups. Examples of these methylolmelamines include hexamethoxymethylmelamine, pentamethoxymethylmelamine, tetramethoxymethylmelamine,
Trimethoxymethylmelamine, hexamethylolpentamethoxymethylmelamine, hexamethyloltetramethoxymethylmelamine, hexamethyloltrimethoxymethylmelamine, pentamethyloltetramethoxymethylmelamine, pentamethyloltrimethoxymethylmelamine, tetramethyloltrimethoxymethylmelamine, etc. I can do it. Incidentally, these methylolmelamines may partially contain dimers connected by --CH ₂ --, --CH ₂ --O--CH ₂ -- bonds. These C components act as crosslinking agents, and exhibit extremely excellent compatibility with components A and B of the present invention, which cannot be obtained with components other than C, such as etherified urea melamine cocondensates. Create a coating film with excellent transparency and adhesion. Component C mentioned above can be obtained by methylolation reaction of melamine and formaldehyde in a methanol solvent, usually under alkaline conditions, and by heating this reaction product under acidic conditions to methylate it, or if necessary, further methylation. It can be obtained by various known methods such as. Next, in the present invention, the total amount of component A and component B is 50 to 90% by weight, component C is 50 to 10% by weight, and the blending ratio of component A and component B is 30 to 70 parts by weight of component A. The reason why component B was limited to 70 to 30 parts by weight is as follows. If the total amount of A component and B component is less than 50% by weight,
If the C component, which acts as a crosslinking agent, is excessive, the antifogging property is reduced, and the film becomes too hard and brittle, resulting in a reduction in adhesion. Furthermore, if the total amount of component A and component B exceeds 90% by weight, component C will be too small and the hardness required for a coating film will be poor, resulting in decreased abrasion resistance and stickiness, resulting in decreased stain resistance. Furthermore, in the blending ratio of A component and B component, A
If the amount of the component is less than 30 parts by weight, the amount of component A, which improves compatibility and improves transparency and hardness by preventing rough skin and whitening, is too small, resulting in a decrease in transparency and hardness. Furthermore, when the amount of component A exceeds 70 parts by weight, the amount of component B, which acts to improve antifogging properties, is too small, resulting in a decrease in antifogging properties. In the resin composition for anti-fog coating of the present invention, in order to obtain even better performance such as anti-fog properties, transparency, adhesion, and abrasion resistance, the total amount of components A and B must be Component C is preferably 60 to 80% by weight, component C is 40 to 20% by weight, and the blending ratio of component A and component B is preferably 30 to 70 parts by weight of component A and 70 to 30 parts by weight of component B. The anti-fog coating resin composition of the present invention, which is composed of the A component, B component, and C component described above, is coated on a substrate to a thickness of, for example, 10 to 100 μm, and then heated to a temperature of 80 to 250° C. by, for example, a hot air dryer. 2, preferably at a temperature of 70-220°C
It can be cured by baking for 120 minutes, preferably 5 to 60 minutes, to form a coating. The antifogging coating resin composition of the present invention can be mixed by any conventionally known method, such as a stirrer, an ink mill, a grinder, a high-speed homomixer, and the like. In addition to the above-described components A, B, and C, the resin composition for antifogging coating of the present invention generally contains a curing catalyst. Typical curing catalysts include organic acids and Salts thereof, such as para-toluenesulfonic acid, phthalic anhydride, benzoic acid, benzenesulfonic acid, formic acid, acetic acid, itaconic acid, oxalic acid, maleic acid and their ammonium salts,
Lower amine salts; inorganic acids and their salts, such as hydrochloric acid,
Examples include nitric acid, sulfuric acid, phosphoric acid, and their ammonium salts, lower amine salts, and polyvalent metal salts. The amount of these catalysts used is 2% by weight or less, preferably 0.01 to 2% by weight, based on the total resin components of component A, component B, and component C.
It is 1% by weight. The anti-fog coating resin composition of the present invention can be used after being diluted with a solvent such as xylene, butanol, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, or paint thinner, if necessary. Modifiers such as plasticizers, stabilizers, ultraviolet absorber dyes, surfactants, etc. can be added to improve the mechanical strength, appearance, etc. These include, for example, as a modifier, vinyl chloride resin, polyvinyl alcohol resin, polyacrylamide resin, polyester resin, epoxy resin,
Synthetic resins such as phthalates, phosphates, epoxidized soybean oil, polyesters,
Plasticizers such as epoxy-based; stabilizers such as lead salt-based, metal soap-based, organotin-based, and epoxy-based; ultraviolet absorbers such as amine-based, phenol-based, and benzotriazole-based; soaps, sulfides, and sulfon Anionic surfactants such as compounds; Cationic surfactants such as aliphatic amine salts, ammonium salts, and alkylamine types; Ester types, ether types, alkylphenol types, and polyethylene glycol-based alkylamide types , nonionic surfactants such as sorbitol fatty acid esters based on polyhydric alcohol partial esters, and mixed types of ester ethers; amphoteric surfactants such as betaine types; and the like. The amounts of these additives are the same as those commonly used in the past. The anti-fog coating resin composition of the present invention has a low viscosity, is easy to handle, and does not cause rough skin, repellency, etc., and can be applied to window glasses that require anti-fog properties.
If necessary, it has an affinity with the resin composition for anti-fog coating of the present invention on the surfaces of molded products such as synthetic resins, eyeglasses, goggles, cosmetic mirrors, road mirrors, show cases, optical lenses, sheets, films, etc. After applying a primer, it can be applied by brush, spray, or roller coating, and then baked and cured in a hot air dryer to create a coating film with excellent transparency and abrasion resistance. Can be formed. The present invention will be explained in more detail below with reference to Examples. Reference Examples 1 to 12 (Preparation of component A)

[Table] Silmercaptan)
Place the mixture in a reaction apparatus equipped with a dropping device, a stirrer, a reflux condenser, and a thermometer, and raise the temperature to 110°C while stirring. After raising the temperature, continuously drop the monomer mixture shown in the table for about 5 hours, and after the addition is complete. The reaction was continued for an additional 2 hours. The resulting reaction solution was concentrated in vacuo to remove nonvolatile components.
A component polymer No. (A-1) of Reference Example 1 with a concentration of 99% was obtained. This No. (A-1) had a number average molecular weight of 1,760 and a hydroxyl value of 110. Using the same method, No. (A-2) to No. (A-
Component A of 12) was obtained. Table 1 also shows the measurement results of the number average molecular weight, hydroxyl value, and acid value (the number of mg of potassium hydroxide required to neutralize the free acid contained in 1 g of the sample) of these A components. The symbols used in the composition column of Table 1 indicate the following. AA...acrylic acid, MA...methyl acrylate, EA...ethyl acrylate, BA...butyl acrylate, 2EHA...2ethylhexyl acrylate, MAA...methacrylic acid, MMA...methyl methacrylate, BMA...butyl methacrylate, 2HEA...
2-Hydroxyethyl acrylate, 2HFMA...2-Hydroxyethyl methacrylate, Reference Examples 13 to 17 (Adjustment of component B) Polyethylene glycol (n= 5)
Add 100 parts by weight, 50 parts by weight of toluene, and 0.5 part of para-toluenesulfonic acid as an esterification catalyst, and raise the temperature to 100°C while stirring.
35 parts by weight of No. (A-7) prepared in step 12 and 25 parts by weight of toluene
Parts by weight of the mixed solution were added over 1 hour, and the reaction was continued for an additional 2 hours. The obtained reaction solution was concentrated in vacuo to remove toluene and water, and a reference example with a nonvolatile content of 98.5% was obtained.
13 B component polymer No. (B-13) was obtained. Using the same method, No. (B-14) to No. (B-
Component B of 17) was obtained. The symbols used in the composition column of Table 2 indicate the following. PEG...polyethylene glycol, PPG...polypropylene glycol, PAA...polyacrylic acid, Example 1 As shown in Table 3, No. (A-2) as component A
The polymer is 30 parts by weight, No. as B component (B-13)
50% by weight of a polymer mixed with component A and component B in a proportion of 70 parts by weight, and hexamethyloltetramethoxymethylmelamine (manufactured by Sanwa Chemical Co., Ltd., trade name MS-11) as component C. ) To 100 parts by weight of an anti-fog coating resin composition consisting of 50% by weight, 100 parts by weight of a mixed solvent consisting of 50% by weight of toluene and 50% by weight of butanol and 1.5 parts by weight of para-toluenesulfonic acid were added and dissolved. A resin composition solution for antifogging coating was prepared. The solution was then applied onto a 3 mm thick glass plate and heated in a hot air dryer at 150°C for 20 minutes to cure and form a coating film with a thickness of about 3 μm on the glass plate. Table 3 shows the results of measuring the antifogging property, transparency, adhesion, abrasion resistance, and hardness of the coating film. The above test was conducted in the following manner. (1) Measurement of antifogging property A coating film test piece formed on a glass plate (thickness 3 mm, length 10 cm, width 5 cm) was placed in a -10℃ freezer for 30 minutes.
After leaving it for a minute, remove it from the freezer and immediately
℃ and relative humidity of 60%, the paint film test piece is placed in a box that is visible from the top, and the time (minutes) until the cloudiness of the paint film that occurs immediately after being placed in the box disappears is measured. The fogging property was evaluated (the shorter the time, the faster the fogging disappears and the better the anti-fogging property is). In addition, in the case of a coating film test piece using a polyester plate as a base instead of a glass plate, the coating film surface was fogged by blowing breath on the coating film test piece at room temperature of 25°C for 2 to 3 seconds, and then the clouding was removed. The antifogging property was evaluated by measuring the time (seconds) until it disappeared. (2) Transparency Transparency was evaluated by visually observing the presence or absence of whitening (turbidity) and rough skin (repellency, orange skin) of the coating film.
For turbidity, a clear state with no turbidity is indicated by ○, and one that is cloudy and has whitening is indicated by an ×; for rough skin, a smooth surface without rough skin is indicated by ○, and one with rough skin is indicated by an × symbol. did. (3) Adhesion Make cuts with a knife in the coating film formed on the glass plate (same as the coating film formed on the polyester plate) at 1 mm intervals to reach the glass plate, and measure the total
Adhesion was evaluated by making 100 squares, pressing cellotape onto the squares, then rapidly peeling off the cellophane tape, measuring the number of squares remaining in close contact with the glass plate without peeling off. . (4) Abrasion resistance The coating film formed on the glass plate is coated with ASTM-D
-674-44, after dropping 1000 g of carborundum, the degree of haze (%) (haze) was measured to evaluate wear resistance. (5) Hardness The hardness of the coating film formed on the glass plate is determined by JIS-K-
The hardness was evaluated by measuring the pencil hardness according to 5400. Examples 2 to 17 and Comparative Examples 1 to 17 As shown in Table 3, a coating resin composition solution was prepared in the same manner as in Example 1 using a coating resin composition of component A, component B, and component C. A coating film was formed on a glass plate in the same manner as in Example 1, or the solution was applied to a polyester plate with a thickness of 5 mm, and the solution was heated in a hot air dryer at 130°C for 40 minutes to harden to a thickness of about 3 μm.
A coating film was formed. Table 3 shows the performance test results of the coating film thus obtained. The symbols used for the C component in the No. column of Table 3 indicate the following. MS-001, pentamethyloltetramethoxymethylmelamine, manufactured by Sanwa Chemical Co., Ltd., trade name Nikaratsuk MS-001; MS-201, methylated urea, manufactured by Sanwa Chemical Co., Ltd., trade name Nikaratsuk MX-201; MD
-101, melamine-urea cocondensation resin, manufactured by Sumitomo Chemical Co., Ltd., trade name Sumimaru MD-101; J-820,
Butylated melamine resin, manufactured by Dainippon Ink Industries, Ltd.
Product name: Super Betsucomin J-820. For reference, the hardness, abrasion resistance, and antifogging properties of the glass plate and polyester plate used in the test were as follows.

[Table] As can be seen from the results of Examples 1 to 17 above, the resin composition for antifogging coating of the present invention exhibits excellent antifogging properties even without the addition of a hydrophilic surfactant, and
It maintained its excellent anti-fog properties even after long-term use.
In addition, this excellent anti-fogging property can usually be obtained by using a single layer coating with a thickness of several micrometers, and there is no need for a multilayer coating made of a complex resin composition as in the past. It has the advantage of being In addition, the A component, B component, and C component of the resin composition for antifogging coating of the present invention have excellent compatibility with each other, resulting in a smooth and transparent coating film without turbidity or rough skin, and is hydrophilic. Since no surfactant is added, a coating film that is free from stickiness, has excellent stain resistance, and maintains transparency for a long period of time can be obtained. Furthermore, since it has excellent abrasion resistance and is hard to scratch, it can be applied to the various fields of antifogging coatings mentioned above.In this case, component A in the resin composition for antifogging coating of the present invention is Since it does not substantially contain free organic acids that react with component C and reduce viscosity stability, the coating solution obtained from the antifogging coating resin composition of the present invention has good storage stability and can be easily coated. It also has the advantage of being paintable.

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Claims (1)

[Scope of Claims] 1. A resin composition for anti-fog coating, wherein (a) component A has the general formula (), (In the formula, R ₁ is H or CH ₃ , R ₂ is 1 carbon number
〜8 alkyl groups), and a repeating unit represented by the general formula (), (In the formula, R ₃ is H or CH ₃ , R ₄ is 1 carbon number
80% by weight of the repeating unit represented by ~6 alkylene groups) in the polymer.
It is a polymer containing the above, and has a number average molecular weight of 500 to 10,000 and a hydroxyl value of 80 to 450, (b) component B has the general formula (), (In the formula, R ₅ is H or CH ₃ , R ₆ is H or
CH ₃ , m is an integer of 1 to 20, n is an integer of 5 to 20), and (c) the C component has about 3 or more methoxymethyl groups per triazine ring. It is methylolmelamine, (d) the total amount of component A and component B is 50 to 90% by weight, and
An anti-fogging coating characterized in that the component is 50 to 10% by weight, and the blending ratio of component A and component B is 30 to 70 parts by weight of component A and 70 to 30 parts by weight of component B. Resin composition.