JP2684679B2 - Method for producing aqueous coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an aqueous coating composition. More specifically, it relates to an aqueous coating composition obtained by polymerizing a radical-polymerizable acrylic monomer in the presence of an aqueous polyurethane resin, which has elasticity and abrasion resistance of a urethane resin, and weather resistance of an acrylic resin, It is a composition functionally linked with toughness and can be widely used as a coating agent for cement, concrete, metal, paper, leather, wood and the like.

[Prior art and its problems] As an aqueous coating composition, an acrylic copolymer aqueous dispersion has been used as a coating or fiber for building interior and exterior, leather, metal, wood, etc. due to its excellent weather resistance and toughness. It has been used for a wide variety of purposes such as impregnation or binder for adhesives, pastes, etc.

However, in recent years, with higher quality, changes in the coating base material, use in new applications, etc., the demand for performance of the coating composition has become highly functional, and in addition to conventional weather resistance,
Applications that require elasticity and abrasion resistance of the film comparable to urethane resin are increasing. To obtain such physical properties,
As a method for improving an acrylic copolymer aqueous dispersion, various acrylic functional group monomers have been studied, but it is difficult to obtain an acrylic resin having elasticity comparable to urethane resin, and the study is desired. It was

On the other hand, an aqueous polyurethane resin as an aqueous coating composition has been conventionally used for coating fabrics, papers, leathers, plastics, wooden floors, etc., paying attention to elasticity and abrasion resistance which are the characteristics of this resin. However, when it is used in a normal dry condition, the water resistance, alkali resistance, and weather resistance, which are considered to be due to the water-soluble substance used for making it water-soluble, and the strength of the cohesive force inside the particles of the urethane dispersion, Due to the poor film-forming property between the particles, which is considered to be caused, the range of use was almost limited to indoors. Further, in practice, in most cases, a crosslinking agent is also used in combination with a high-temperature heat drying treatment, and the elasticity peculiar to the urethane resin is obtained only under these conditions.

In order to develop an aqueous coating composition that has not only elasticity and abrasion resistance of urethane resin but also weather resistance and toughness of acrylic resin, mixing of aqueous polyurethane resin and acrylic copolymer water dispersion, etc. However, the mere mixing, on the contrary, has the drawbacks of the respective resins, namely, the weak elasticity of the acrylic copolymer aqueous dispersion,
In many cases, only a combination of the properties of the aqueous polyurethane resin and the poor weather resistance can be obtained, and the development of a resin that combines the properties of both has been eagerly awaited.

[Means for Solving the Problems] The present inventors have conducted research to develop an aqueous coating composition having not only elasticity and abrasion resistance of urethane resin but also weather resistance and toughness of acrylic resin. As a result of overlapping
The present invention has been completed by finding that the above problems can be solved by functionally linking both the aqueous polyurethane resin and the acrylic copolymer aqueous dispersion, rather than simply mixing them. .

That is, the present invention is an aqueous polyurethane resin obtained by neutralizing a urethane prepolymer obtained by reacting a diisocyanate and a glycol containing a carboxylic acid group-containing glycol, and chain-extending with a hydrazine derivative. In the presence of (A), the carbonyl group-containing monomer or the amide group-containing monomer is added to 100 parts by weight of the total polymerizable monomer.
The radical-polymerizable acrylic monomer (B) containing at least 0.5 part by weight has a solid content weight ratio of (A) /
(B) = 100/5 to 5/100 The method for producing an aqueous coating composition is characterized in that the polymerization is performed.

 Hereinafter, the present invention will be described in detail.

The aqueous polyurethane resin used in the present invention is produced, for example, as follows. That is, first, a diisocyanate, a glycol and a glycol having a carboxylic acid group are subjected to a urethane reaction to obtain a urethane prepolymer.

The diisocyanates used at this time include aliphatic, alicyclic or aromatic diisocyanates, and examples of these include 2,4-tolylene diisocyanate and 2,6.
-Tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, m-phenylene diisocyanate, xylylene diisocyanate, tetramethylene diisocyanate, lysine diisocyanate, 1,4-cyclohexylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3 '-Dimethyl-4,4'-
Biphenylene diisocyanate, 3,3'-dimethoxy-
4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate and the like can be mentioned.

As the glycols for preparing the urethane prepolymer, low molecular weight glycols, high molecular weight glycols, polyester polyols, polycarbonate polyols and the like may be used alone, respectively, and they are well known in the urethane technology. In addition, low molecular weight glycol may be used in combination with polyester polyol or high molecular weight glycol.

As low molecular weight glycols, ethylene glycol, diethylene glycol, triethylene glycol,
1,2-propylene glycol, 1,3-butylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, octanediol, tricyclodecane dimethylol, hydrogenated bisphenol A,
There are cyclohexanedimethanol and the like, and two or more kinds thereof may be mixed.

High molecular weight glycols include polyethylene glycol,
Examples thereof include polypropylene glycol and polytetramethylene glycol.

The polyester polyols may be those obtained by reacting a glycol component and a dicarboxylic acid component, and can be easily produced by a known method. That is, the transesterification reaction is not limited to the esterification reaction. That is, the polyester polyol of the present invention can also be produced by a transesterification reaction using a lower alkyl ester of glycol and dicarboxylic acid.

As the polyester polyols used in the present invention, if a glycol component and an unsaturated dicarboxylic acid are reacted, the functional bond with the radically polymerizable acrylic monomer becomes stronger, and the obtained aqueous coating The agent composition becomes more preferable.

Examples of the unsaturated dicarboxylic acid that can be used at this time include itaconic acid, maleic acid, phthalic acid and the like. Also,
Other dicarboxylic acids include, for example, isophthalic acid,
Examples thereof include terephthalic acid, succinic acid, adipic acid, malonic acid, sebacic acid and azelaic acid. Further, lower alkyl esters of these dicarboxylic acids are also included.
These dicarboxylic acids are used alone or in combination.

Glycols having a carboxylic acid group include 2,2-
Dimethylolpropionic acid, 2,2-dimethylolbutyric acid,
2,2-dimethylol valeric acid and the like can be mentioned.

The reaction includes dioxane, acetone, methyl ethyl ketone, N-methylpyrrolidone, tetrahydrofuran, etc.
It is desirable to carry out in an organic solvent which is inert to isocyanate groups and has a high affinity for water.

Then, the prepolymer is neutralized and chain-extended, and distilled water is added to obtain an aqueous polyurethane resin. The organic solvent used in the reaction may be removed by a known method as necessary.

Examples of the neutralizing agent include amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine and triethanolamine; sodium hydroxide, potassium hydroxide, ammonia and the like.

In the present invention, it is a requirement to use a hydrazine derivative as a chain extender. As the hydrazine derivative, hydrazine, ethylene-1,2-dihydrazine, propylene-
Examples thereof include 1,3-dihydrazine and butylene-1,4-dihydrazine.

Generally as a chain extender for urethane prepolymer,
Polyols such as ethylene glycol and propylene glycol; ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, 2-
Methyl piperazine, aliphatic such as isophorone diamine, alicyclic and aromatic diamines are well known, but in the present invention, such a compound is a urethane resin when emulsion-polymerizing a radically polymerizable acrylic monomer. No effect is observed on the functional connection of acrylic resin.

That is, it is necessary to hold the chemical structure of --NHNH ₂ at the polymer molecule end of the aqueous polyurethane resin obtained when the chain extension of the urethane prepolymer is performed, and by holding this chemical structure, For the first time, it can be functionally linked to a carbonyl group-containing monomer or an amide group-containing monomer in a radically polymerizable acrylic monomer.

In the present invention, the acid value in the aqueous polyurethane resin is preferably 10 to 200 per resin solid component. When the acid value is less than 10,
When the urethane prepolymer reacted in an organic solvent is made aqueous with a neutralizing agent, a chain extender, and distilled water, aggregates are likely to occur, and the storage stability of the obtained aqueous polyurethane resin may be poor. . On the other hand, if the acid value exceeds 200,
When the acrylic resin is functionally bound, preferable physical properties such as durability and water resistance may not be obtained.

As the radical polymerizable acrylic monomer used to obtain the aqueous coating composition of the present invention, a carbonyl group-containing monomer or an amide group-containing monomer relative to 100 parts by weight of the total radical polymerizable acrylic monomer, at least
Although it is necessary to contain 0.5 part by weight, conventionally known surfactants, protective colloids and polymerization initiators can be used for emulsion polymerization.

The carbonyl group-containing monomer is a monomer containing an aldo group or a keto group, and has an ester bond. And carboxyl groups Compounds having only are not included in this monomer. Examples of the carbonyl group-containing monomer corresponding to the present invention,
Examples thereof include acrolein, diacetone acrylamide, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone, diacetone acrylate and acetonitrile acrylate.

Examples of the amide group-containing monomer include monoolefinic unsaturated carboxylic acid amides, N-alkyl derivatives of monoolefinic unsaturated carboxylic acid amides, and N-alkylol derivatives of monoolefinic unsaturated carboxylic acid amides. . Examples of applicable monomers are amides of acrylic acid, methacrylic acid, itaconic acid or maleic acid; N-methylacrylamide, N-isobutylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-methylolmethacryl. Amide,
Examples thereof include N-ethoxymethylacrylamide, Nn-butoxymethylacrylamide, N-isopropoxymethacrylamide and the like.

These carbonyl group-containing monomers or amide group-containing monomers may be used alone or in combination, but at least 0.5 part by weight is necessary for 100 parts by weight of the total polymerizable monomer. The particularly preferable range is 1.0 to 10.0 parts by weight. When the amount is less than 0.5 part by weight, the functional effects of the aqueous polyurethane resin and the acrylic resin are not recognized, and it is difficult to obtain a remarkable improvement in physical properties such as weather resistance, water resistance, alkali resistance, elasticity and abrasion resistance.

In addition, examples of acrylic monomers other than the above that are used for emulsion polymerization in the present invention include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; methyl methacrylate,
Examples thereof include methacrylic acid esters such as ethyl methacrylate.

In the present invention, other polymerizable unsaturated monomers that can be copolymerized with the above acrylic monomer can also be used.

Examples of the polymerizable unsaturated monomer include maleic acid, fumaric acid, itaconic acid esters; vinyl acetate, vinyl propionate, tertiary vinyl carboxylate and other vinyl esters; styrene, vinyltoluene, etc. Such as aromatic vinyl esters; heterocyclic vinyl compounds such as vinylpyrrolidone; vinyl chloride, acrylonitrile, vinyl ether, vinyl ketone, vinylamide, etc .; vinylidene halide compounds such as vinylidene chloride, vinylidene fluoride, .alpha.-, such as ethylene, propylene, etc. Olefins;
Dienes such as butadiene may be mentioned.

As the polymerizable unsaturated monomer having a reactive polar group, glycidyl acrylate, glycidyl methacrylate, glycidyl compounds such as allyl glycidyl ether; vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ
A silane compound such as methacryloxypropyltrimethoxysilane; acrylic acid, methacrylic acid, maleic acid or a half ester thereof, fumaric acid or a half ester thereof,
Carboxylic compounds such as itaconic acid or its half ester and crotonic acid; hydroxylic compounds such as β-hydroxyethyl acrylate and β-hydroxyethyl methacrylate; amine compounds such as alkylamino acrylate and alkylaminomethacrylate.

In the present invention, in the presence of an aqueous polyurethane resin, the radical polymerizable acrylic monomer is emulsion-polymerized to obtain an aqueous coating composition, and the aqueous polyurethane resin is used in the reaction of the radical polymerizable acrylic monomer. Therefore, the surfactant (emulsifier) is not always necessary, but the radical polymerizable acrylic monomer 10
The surfactant (emulsifier) may be used in the range of 0 to 10 parts by weight with respect to 0 parts by weight. As the surfactant (emulsifier) at this time, a conventionally known one can be used.

Examples of the surfactant include anionic emulsifiers such as sodium dodecylbenzene sulfate, sodium dodecylbenzenesulfonate, and alkylaryl polyether sulfate; polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene- Nonionic emulsifiers such as polyoxypropylene block copolymers; cationic emulsifiers such as cetyltrimethylammonium bromide, laurylpyridinium chloride and the like can be appropriately selected and used. It is also possible to use the water-soluble oligomer as a dispersant in place of the emulsifier as described above or in combination with the emulsifier. Further, it is also effective to use a water-soluble polymer substance such as polyvinyl alcohol or hydroxyethyl cellulose together with the above emulsifier or to add it to the emulsion after polymerization.

The total amount of the emulsifier, water-soluble oligomer and water-soluble polymer substance used is preferably in the range of 0 to 10 parts by weight with respect to 100 parts by weight of the radical-polymerizable acrylic monomer. When it is more than this range, the water resistance of the coating film of the final aqueous coating composition may be significantly lowered, which is not preferable.

As the radical polymerization initiator used in the emulsion polymerization to obtain the aqueous coating composition of the present invention, those used in ordinary emulsion polymerization are used, examples of which include potassium persulfate, Examples thereof include ammonium persulfate, azobisisobutyronitrile and hydrochloride thereof, and organic peroxides such as cumene hydroperoxide and tert-butyl hydroperoxide can also be used as necessary. Further, known redox initiators using a combination of these persulfates or peroxides with a metal ion such as iron ion and a reducing agent such as sodium sulfoxylate formaldehyde, sodium pyrosulfite, and L-ascorbic acid may also be used. Can be used.

From a practical point of view, the concentration during emulsion polymerization should be such that the final composition has a solid content concentration of 25 to 65% by weight, and the concentration of ethylenically unsaturated monomers and radical polymerization in the reaction system. The initiator can be added by any known method such as batch charging, continuous dropping and divided addition.

The temperature at the time of emulsion polymerization may be in the range which is known in the known emulsion polymerization, and the emulsion polymerization is carried out under normal pressure, or under pressure when a gaseous ethylenically unsaturated monomer is used.

In the present invention, in the presence of an aqueous polyurethane resin chain-extended with a hydrazine derivative, by emulsion-polymerizing a radically polymerizable acrylic monomer containing a carbonyl group or an amide group, at the time of film formation of emulsion particles, the inside of the particles and the particles The functional connection between them is strongly developed.

This bond is considered to be caused by the chemical structure of the hydrazine group at the polymer molecule end of the aqueous polyurethane resin and the carbonyl group or amide group in the acrylic polymer, which causes an organic reaction when the film is dehydrated, It is an aqueous coating composition that organically combines the functions of a condensation resin and a radical polymerization resin.

More specifically, the aqueous coating composition of the present invention has not only the elasticity and abrasion resistance of the urethane resin, but also the weather resistance and toughness of the acrylic resin, and the solvent resistance. , Each is significantly improved over the resin alone. For example, a coating film obtained from an aqueous polyurethane resin is easily dissolved in ketones such as methyl ethyl ketone, and a coating film obtained from an acrylic emulsion synthesized by removing the aqueous polyurethane resin is easily dissolved in toluene. . However, an aqueous coating composition satisfying the requirements of the present invention becomes insoluble in both methyl ethyl ketone and toluene solvents.

On the other hand, an aqueous polyurethane resin lacking the requirements of the present invention
Acrylic resin composite has elasticity of urethane resin,
It cannot have both abrasion resistance and weather resistance and toughness that an acrylic resin has. Further, regarding the solvent resistance, no compounding effect is recognized, and it is easily soluble in both solvents.

The mixing ratio of the aqueous polyurethane resin and the radical-polymerizable acrylic monomer is 100/5 to 5/100 in terms of the solid content weight ratio.
It is a requirement of the present invention to be in the range of 100/10 to 10/1
The range of 00 is more preferable. If it deviates from this range, it will be difficult to combine the characteristics possessed by the urethane resin and the acrylic resin, and it will be difficult to obtain the coating film having the characteristics as described above. By adjusting the mixing ratio of the aqueous polyurethane resin and the radically polymerizable acrylic monomer within the range of the present invention, the characteristics of the urethane resin or the characteristics of the acrylic resin can be emphasized.

The aqueous coating composition of the present invention is used in the same manner as the structure of an aqueous coating composition using a conventional acrylic copolymer aqueous dispersion, and it is used as a clear coating or by adding a pigment. To be That is, pigments, fillers, aggregates, dispersants, wetting agents, thickeners and / or rheology control agents, defoamers, plasticizers, film-forming aids, organic solvents, preservatives, antifungal agents, pH adjustment Agents, rust preventives, etc. are selected and combined according to their respective purposes, and are made into a paint by a usual method.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. In the following, both parts and% are values based on weight.

Production Example 1 Production of Aqueous Polyurethane Resin (A) 1,780 g of 1,6-hexanediol, 2545 g of adipic acid and 567 g of 2,2-dimethylolpropionic acid were mixed to 170 ° C.
OH
A polyester polyol having a valency of 60 and an acid value of 60 was obtained.

This polyester polyol was diluted by adding 1815 g of methyl ethyl ketone. After 240 g of the polyester polyol solution (I), 220 g of methyl ethyl ketone, 30 g of 2,2-dimethylolpropionic acid and 27 g of cyclohexanedimethanol were sufficiently stirred and mixed at 70 ° C., 4,4′-
Add 236 g of dicyclohexylmethane diisocyanate
The temperature was raised to 80 ° C., the reaction was carried out for 6 hours, and then the mixture was cooled to 30 ° C. to obtain a urethane prepolymer solution.

This polyurethane prepolymer solution was
An 80% aqueous hydrazine solution (40 g) and triethylamine (40 g) were gradually poured into an amine aqueous solution obtained by dissolving 1500 g of ion-exchanged water under high speed stirring to obtain a viscous semitransparent product.
After removing the solvent under reduced pressure at 55 ° C, ion-exchanged water was added to adjust the concentration, and the nonvolatile content was 23.7% and the viscosity (BM
Viscometer, 60 rpm, 25 ° C.) A translucent aqueous polyurethane resin (A-1) having 23 cPs and pH 8.4 was obtained.

In the same manner as above, the raw materials shown in Table-1 were used to prepare an aqueous polyurethane resin (A-2) having the properties shown in Table-1.

Examples 1-5, Comparative Examples 1-5 The following were prepared as raw materials.

Radical polymerizable monomers (B) 2-Ethylhexyl acrylate 265 g Styrene 165 g Acrylonitrile 50 g Acrylic acid 10 g Diacetone acrylamide 10 g Surfactants Newcol 707SF (solid content 30%) ^{* 1)} 50 g Ion exchange Water 360 g Polymerization initiator Ammonium persulfate 2.5 g * 1) Special anion emulsifier manufactured by Nippon Emulsifier Co., Ltd. Surfactant 30 g, ion-exchanged water 210 in a four-necked flask.
g, 1054 g of the aqueous polyurethane resin (A-1) were charged, stirring was started, the temperature was raised to 80 ° C. in a nitrogen stream, and then a polymerization initiator was added. Next, 500 g of the radical-polymerizable monomers (B), 20 g of a surfactant, and 150 g of ion-exchanged water were mixed to prepare a monomer pre-emulsion, and this monomer pre-emulsion was added dropwise to the above flask over 3 hours. The reaction temperature at this time was maintained at 80 ± 3 ° C.

After the dropping, the reaction is continued under stirring while maintaining the same temperature range for 2 hours, then cooled and adjusted to pH 8-9 with 14% ammonia water, the nonvolatile content is 38.0%, the viscosity is 200 cPs, p.
An aqueous coating composition of H8.5 (Example 1) was obtained.

Furthermore, in the same manner as in Example 1, the raw materials shown in Table 2 were used to obtain aqueous coating composition (Examples 2 to 5, Comparative Examples 1 to 5). The results are shown in Table-2.

Comparative Example 6 In Example 1, the aqueous polyurethane resin (A-1)
Emulsion polymerization was carried out in the same manner as in the composition and reaction conditions of Example 1 except that the above was not used at all to obtain an acrylic emulsion.

This emulsion has a non-volatile content of 55.1% and a viscosity of 3300 cP.
s, pH 8.5.

Comparative Example 7 For a comparative experiment for evaluating the effect of the acrylic polymer, the aqueous polyurethane resin (A-1) was used as it is as Comparative Example 7.

Regarding the aqueous coating composition thus obtained,
The physical properties of the film were tested in a single state with no additives added. Table 3 shows the results.

Test method (1) Water resistance: A sample was applied to a glass plate with a 3 mil applicator to form a film. After drying at room temperature for 3 days, the film is immersed in water. After soaking at room temperature for 7 days, the film state is visually evaluated.

(○: good, Δ: normal, ×: bad, the same applies below) (2) Alkali resistance: The film prepared in the same manner as (1) was immersed in a 2% sodium hydroxide aqueous solution for 7 days, and then the film state was changed. Determined visually.

(3) Solvent resistance: A film prepared in the same manner as (1)
Immerse in toluene and methyl ethyl ketone for 1 day, and visually judge the film state.

(4) Abrasion resistance: A sample is applied to a standard tile for JFPA standard test (vinyl asbestos tile) so that 10 ± 2 ml per square meter. After the test piece coated 5 times by the same operation method was dried at room temperature for 7 days, the abrasion degree was measured and evaluated by a Taber tester (wearing wheel CS-17, load 1000 g).

(5) Film strength and elongation; the sample was poured onto a glass plate,
It was used after drying for 7 days. The sample was collected so that the film thickness after drying would be 0.2 mm.

(6) Flow initiation temperature: As a sample, 1.5 to 2.0 g of a film dried on a glass plate for 7 days is used. Temperature rising rate 3 ℃ /
Flow start temperature is measured with min, load 30kgf and die 1mmφ × 1mml.

Test Results As can be seen from Table-3, the aqueous coating composition of the present invention, compared to other compositions that do not meet the requirements of the invention,
The abrasion resistance, solvent resistance, and film elongation are remarkably excellent. In addition, the flow starting temperature is also markedly higher, and it can be seen that there is a functional connection between the aqueous urethane resin and the acrylic resin.

The following coating composition was prepared using each of the aqueous coating composition obtained in the composition of Table-2 to prepare an elastic coating composition.

(Compound) Taipaque R-930 ^{* 6)} 100.0 Hi-Metroses 90SH-15000 ^{* 7)} 0.6 Primal 850 ^{* 8)} 1.0 5% KTPP (potassium tripolyphosphate) 2.0 Neugen EA-120 ^{* 9)} 1.0 Adecanol SX-568 ^{* 10 )} 2.5 Ethylene glycol 10.0 Water 35.2 28% Ammonia water 1.0 Disperse the above composition with a high speed disperser and add the following composition.

39% emulsion of each aqueous coating composition ^{* 11)} 391.0 Texanol 26.4 Xylene 6.6 Adecanol UH-420 ^{* 12)} / Water = 1/2 (adjusted by paint viscosity) Total 577.3 NV (%) 43.7 PVC (%) 15.2 PWC (%) 39.6 * 6) Rutile type titanium oxide; Ishihara Sangyo Co., Ltd. * 7) Methyl cellulose; Shin-Etsu Chemical Co., Ltd. * 8) Polycarboxylic acid type dispersant; Rohm and Haas Company (USA) * 9) Interface Activator; Dai-ichi Kogyo Seiyaku Co., Ltd. * 10) Defoamer; Asahi Denka Co., Ltd. * 11) Adjusted by the non-volatile content (%) of emulsion * 12) Thickener; Asahi Denka Co., Ltd. Examples 1 to 5 and Comparative Examples 1 to 7
The applied physical properties of the above aqueous coating composition were tested.

 The results are shown in Table-4.

Test method Paint viscosity; BH type 4 rpm paint viscosity (cPs) Coating gloss: Coated on a glass plate with a 3 mil applicator, dried at 1 day and measured 60 ° reflectance (%).

JIS A6910; Elongation rate ... A test piece was prepared so that the coating film thickness was about 1 mm when dry, then cured according to the JIS elongation test method and punched with a No. 2 dumbbell to obtain a test piece.

(Coating → curing for 7 days → curing for 7 days on back side → punching) Deterioration during elongation ... The above test pieces were punched test pieces with No. 1 dumbbell.

Adhesion strength ... Apply Acridic 53-448 as an undercoat, dry for 3 hours, then apply the sample according to the test method.
The four sides of the test piece used for the test after 14 days of curing and the adhesion strength after immersion in water were coated with a vinyl chloride resin paint 3 days before the completion of curing. The adhesive used was a two-part epoxy adhesive.

Resistance to repeated hot and cold action: (20 ± 2 ℃ 18Hrs in water → -20 ± 3 ℃ × 3Hrs → 50 ± 3 ℃ × 3
Hrs) × 10 cycles Water permeability… Conforms to JIS elongation test method Impact resistance… 〃Weather resistance… 〃Film strength; JIS A6910 Displays the film strength at the time of measuring elongation.

Accelerated weathering resistance: Measure the coating film elongation at 20 and -10 ° C after irradiating a standard weather meter with a coating film similar to that for which elongation was measured for 500 hours.

Test Results As can be seen from Table-4, the aqueous coating composition of the present invention has good weather resistance even when a pigment is added, and exhibits the property that the coating film strength does not deteriorate even after immersion in water.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication C08G 18/83 C08G 18/83

Claims (1)

(57) [Claims] 1. An aqueous polyurethane resin obtained by neutralizing a urethane prepolymer obtained by reacting a diisocyanate with a glycol containing a carboxylic acid group-containing glycol, and chain-extending with a hydrazine derivative. (A)
In the presence of a radical-polymerizable acrylic monomer (B) containing at least 0.5 part by weight of a carbonyl group-containing monomer or an amide group-containing monomer based on 100 parts by weight of the total polymerizable monomer, The weight ratio is (A) / (B) = 100 /
A method for producing an aqueous coating composition, which comprises polymerizing at a ratio of 5 to 5/100.