JP2002146268A - Two-pack, water-based top coating material composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a top coating material composition more excellent in adhesion to a waterproof material as a substrate than conventional water-based top coating materials, exhibiting sufficient extending properties as a coating film and not suffering from cracks, and the like, in the coating film. SOLUTION: The two-pack water-based top coating material composition comprises a water-based resin composition, comprising (A) an aqueous solution or an aqueous dispersion of an acrylic copolymer and 5-40 wt.% (solids content ratio), based on (A), of (B) a urethane dispersion, and, incorporated therewith, (C) a self-emulsifying polyisocyanate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-pack type water-based topcoat composition, and more particularly to a two-pack type water-based topcoat composition for a waterproof material which can protect the waterproof material and impart aesthetic properties to the waterproof material. About things.

[0002]

2. Description of the Related Art For the purpose of protection and aesthetics of a waterproof material applied to a concrete layer, a two-component urethane paint is overcoated on the surface of the waterproof material. Organic solvent-based paints have been generally used as two-part urethane paints used for such purposes, but in recent years, water-based paints have been strongly demanded from the viewpoint of ensuring the safety of the global environment and work environment. Is coming.

Therefore, research and development using an aqueous dispersion of an acrylic resin or a urethane resin as a water-based topcoat have been advanced, but such a topcoat has poor adhesion to a waterproofing material as a base, and There is a problem that the extensibility of the top coat with respect to the elongation of the waterproof material is insufficient, and further, there is a problem that the coating film after application of the top coat has cracks, etc. A topcoat has not yet been obtained. In particular, in the case of a top coat composed of an aqueous dispersion of an acrylic resin or a urethane resin, there were cases where the top coat did not adhere to the urethane waterproofing material at all.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above situation, and its object is to provide:
It is an object of the present invention to provide a topcoat that is superior to conventional organic solvent-based topcoats in terms of protecting the global environment and ensuring work safety.

Further, an object of the present invention is to provide a water-based top coat which is superior in adhesion to a waterproof material as a base material, as compared with conventional water-based top coats.
It is still another object of the present invention to provide an overcoat that has sufficient extensibility as a coating film and does not cause cracks or the like in the coating film.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the main ingredient of an aqueous resin composition comprising an aqueous solution or dispersion of an acrylic copolymer and a urethane dispersion has a self-curing agent as a curing agent. It has been found that the use of a two-pack waterborne topcoat composition containing an emulsified polyisocyanate makes it possible to obtain a topcoat excellent in adhesion, extensibility and appearance of the coating film, and has completed the present invention.

[0007] In short, the present invention relates to an aqueous solution or dispersion of an acrylic copolymer (A), and 5 to 4
The present invention relates to a two-pack waterborne topcoat composition comprising a waterborne resin composition containing 0% by weight (solid content) of a urethane dispersion (B) and a self-emulsifying polyisocyanate (C).

Here, in order to form a uniform resin coating, each component of an aqueous solution or aqueous dispersion of an acrylic copolymer (A), a urethane dispersion (B) and a self-emulsifying polyisocyanate (C) is used. Preferably have good compatibility.

As the urethane dispersion (B), it is preferable to use a urethane dispersion comprising a polyether polyol and a non-yellowing type isocyanate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the two-pack waterborne topcoat composition of the present invention is an aqueous resin composition containing an aqueous solution or dispersion (A) of an acrylic copolymer and a urethane dispersion (B). A self-emulsifying type polyisocyanate (C) is blended as a hardening agent with a base material made of a product. Hereinafter, each component used in the coating composition of the present invention will be described in detail.

First, the aqueous solution of the acrylic copolymer of the present invention is not particularly limited, and any aqueous solution may be used as long as the object of the present invention is not impaired. An aqueous solution of an acrylic copolymer obtained by the above method can be used.

The aqueous dispersion of the acrylic copolymer can be obtained, for example, by the following method. That is, first, a copolymer of an acrylic monomer is synthesized by solution radical polymerization, and after the synthesis, a carboxylic acid present in the main chain of the copolymer is neutralized with a neutralizing agent to obtain good dispersibility in water. For example, it is neutralized with a tertiary amine such as triethylamine and dimethylmonoethanolamine. Next, the obtained copolymer solution is dispersed in pure water and uniformly dispersed, and then the solvent is removed by distillation under reduced pressure. In the solution radical polymerization of an acrylic monomer, methyl ethyl ketone (ME
It is preferred to use K) as a solvent. In the present invention, it is preferable to use an aqueous dispersion of an acrylic copolymer as (A) in view of the crack resistance of the top coating film.

The acrylic monomers include, for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n
-Butyl methacrylate, isobutyl methacrylate,
n-hexyl methacrylate, lauryl methacrylate, acrylic acid, methacrylic acid, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate,
Examples thereof include 2-hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl methacrylate, and cyclohexyl methacrylate. In addition,
Acrylic monomers may be used alone or in combination of two or more.Methyl methacrylate, cyclohexyl methacrylate, monomers having excellent weather resistance such as methacrylic acid, n-butyl acrylate,
It is preferable to use in combination with a monomer such as hydroxyethyl methacrylate and acrylic acid which can contribute to adhesion.

The acrylic copolymer of the present invention may be a copolymer of the above-mentioned acrylic monomer and another monomer. Other monomers used for copolymerization with acrylic monomers include styrene, vinyl toluene, vinyl acetate, acrylonitrile, acrylamide,
N-methylol acrylamide, diacetone acrylamide, maleic acid, itaconic acid and the like can be mentioned.

Here, the hydroxyl value of the acrylic copolymer (O
H value) is 10 to 180 (mgkOH / g, solid)
And an acid value of 1 to 50 (mg kOH / g, soli
d) is preferable, and the average particle size of the acrylic copolymer in the aqueous dispersion is preferably in the range of 0.01 to 2.0 μm. Further, the Tg of the acrylic copolymer is 10 in terms of adhesion to a waterproof material and stain resistance.
It is preferable to be in the range of -45 ° C.

The urethane dispersion of the present invention can be obtained by reacting a polyol component, an isocyanate component and a polyhydroxycarboxylic acid. In the present invention, by adding a urethane dispersion to the coating composition, it is possible to improve the crack resistance of the coating film during drying and to impart elasticity to the coating film.

The adhesion, elongation, stain resistance,
It is preferable to use a polyether-based polyol as the polyol component from the viewpoints of alkali resistance, acid resistance, abrasion resistance and the like. As the polyether-based polyol, for example, homopolymers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol,
Examples include block copolymers and random copolymers. Further, the weight average molecular weight (Mw) of the polyether polyol is preferably from 400 to 5000, more preferably from 700 to 3000, from the viewpoint of the hydrolysis resistance of the top coat and the followability to the elongation of the waterproof material. is there.

On the other hand, the non-yellowing aliphatic or alicyclic diisocyanate is preferably used as the isocyanate component. Examples thereof include hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, lysine diisocyanate, isopropylidene bis (4-cyclohexyl isocyanate), hydrogenated xylylene diisocyanate, dicyclohexyl diisocyanate, and the like. Among these, hexamethylene diisocyanate, isophorone diisocyanate and hydrogenated xylylene diisocyanate are particularly preferred.

The polyhydroxycarboxylic acid used here is introduced to improve the dispersibility of polyurethane in water. Specifically, dimethylolpropionic acid, dimethylolbutanoic acid, Examples thereof include 2,2-dimethylolbutyric acid and 2,2-dimethylolvaleric acid. Among these, it is particularly preferable to use dimethylolbutanoic acid in consideration of compatibility with the acrylic copolymer.

The amount of the urethane dispersion is 5 to 40 with respect to the aqueous solution or the aqueous dispersion of the acrylic urethane copolymer from the viewpoint of the balance between the weather resistance, the adhesion and the elongation.
% (Solid content ratio), more preferably 10 to 35% by weight, and most preferably 15 to 30% by weight.

As a specific method for producing the urethane dispersion of the present invention, first, an organic solvent inert to isocyanate groups such as dioxane, acetone, methyl ethyl ketone, N-methylpyrrolidone and tetrahydrofuran and having a high affinity for water is used. In the reaction, a polyol component, an isocyanate component, and a polyhydroxycarboxylic acid are reacted, and then a neutralizing agent and a chain extender are appropriately added to the obtained prepolymer, and distilled water is further added to obtain a urethane dispersion.

Examples of the chain extender include polyols such as ethylene glycol and propylene glycol, ethylenediamine, propylenediamine, hexamethylenediamine, tolylenediamine, xylylenediamine, diphenyldiamine, diaminodiphenylmethane, diaminocyclohexylmethane, piperazine, and the like. There are aliphatic, alicyclic and aromatic diamines such as 2-methylpiperazine and isophoronediamine and water, and as the neutralizing agent,
Amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, triethanolamine, sodium hydroxide, potassium hydroxide,
Ammonia and the like.

The urethane dispersion of the present invention preferably has a solid content of 20 to 60% and a pH of 7 to 10. Further, the acid value in the urethane resin is preferably from 5 to 50 mgKOH / g per solid resin, and the hydroxyl value in the urethane resin is preferably from 1 to 20 mgKOH / g per solid resin. Further, the weight average molecular weight of the urethane resin is preferably from 10,000 to 200,000 (in terms of polystyrene).

The self-emulsifying polyisocyanate of the present invention refers to an NCO group-terminated prepolymer obtained by adding a polyol to an organic polyisocyanate, adding an isocyanurate-forming catalyst to introduce an isocyanurate ring structure, and forming an unreacted monomer. Is a self-emulsifying polyisocyanate imparted with hydrophilicity, which is obtained by reacting a hydrophilic surfactant having an active hydrogen group capable of reacting with an NCO group after removing the NCO group. The self-emulsifying polyisocyanate of the present invention is obtained by adding a hydrophilic surfactant having an active hydrogen group capable of reacting with a polyol and an NCO group to an organic polyisocyanate, and then adding an isocyanurate-forming catalyst to the isocyanurate ring. The structure may be introduced to remove unreacted monomers.

Specific examples of the organic polyisocyanate used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
4'-diphenylmethane diisocyanate, 2,4'-
Diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4 ' -Diisocyanate,
4,4'-diphenylpropane diisocyanate, m-
Aromatic isocyanates such as phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, and 3,3′-dimethoxydiphenyl-4,4′-diisocyanate; 1,6-hexamethylene Aliphatic isocyanates such as diisocyanate, 1,4-tetramethylene diisocyanate and lysine diisocyanate; araliphatic diisocyanates such as xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate; isophorone diisocyanate, water-added tolylene diisocyanate, water Alicyclic diisocyanates such as added xylene diisocyanate, water-added diphenylmethane diisocyanate, and water-added tetramethyl xylene diisocyanate; and Like compounds and NCO-terminated compounds by reaction with an active hydrogen group-containing compound.

Further, instead of the above-mentioned polyisocyanate obtained by adding a polyol to an organic isocyanate and further adding an isocyanurate-forming catalyst to introduce an isocyanurate ring structure, a polymer of the diisocyanate or a polyol having two or more functional groups is used. Or a polyisocyanate obtained by a reaction with a polymeric compound. That is, any of a polymer of a polyisocyanate and a polyol adduct of a polyisocyanate can be used in the present invention. Further, it may contain an isocyanate-modified product by a reaction of these compounds, for example, a uretdionation reaction, a carbodiimidation reaction, a uretonimination reaction, a Burette reaction, or the like. These polyisocyanates can be used alone or in a mixture of two or more.

Among these polyisocyanates, aliphatic or alicyclic polyisocyanates are preferable in consideration of the stability of water dispersion, the stability of NCO groups after water dispersion, and no yellowing.

The total NC of the organic polyisocyanate of the invention
Examples of the polyol having a reactivity with an isocyanate group for urethanizing a part (0.5 to 15% by weight) of the O group include ethylene glycol, 1,3-butanediol,
Neopentyl glycol, 2,2-diethyl-1,3-
Propanediol, 2-n-butyl-2-ethyl-1,
3-propanediol, 2,2,4-trimethyl-1,
3-pentanediol, 2-ethyl-1,3-hexanediol, 2-n-hexadecane-1,2-ethylene glycol, 2-n-eicosan-1,2-ethylene glycol, 2-n-octacosan-1, 2-ethylene glycol, water-added bisphenol A, dipropylene glycol, 3-hydroxy-2,2-dimethylpropyl-3
-Hydroxy-2,2-dimethylpropionate and the like. Their molecular weight is preferably from 62 to 3,000, more preferably from 100 to 1,000.
By introducing these polyols, the compatibility with the aqueous solution or aqueous dispersion of the acrylic copolymer can be improved.

The method for producing the self-emulsifying polyisocyanate of the present invention may be in accordance with a known method, and is generally carried out in the absence of a solvent. If necessary, a conventional inert solvent, catalyst or the like may be used. And generally 50 to 10
It is performed at a temperature of 0 ° C.

In the present invention, a component required as a coating material, for example, a pigment, is added to a main component comprising an aqueous resin composition containing an aqueous solution or aqueous dispersion of an acrylic copolymer (A) and a urethane dispersion (B). Dyes, dispersants, leveling agents (surfactants), UV absorbers, antioxidants,
Film-forming aids, preservatives, fungicides, defoamers, pH regulators, light stabilizers, inorganic and organic fillers, plasticizers, lubricants, antistatic agents, reinforcing materials, etc., detract from the purpose of the present invention. You may make it contain suitably within the range which does not exist.

The curing agent comprising the self-emulsifying polyisocyanate (C) of the present invention may contain other substances, if necessary, such as a viscosity modifier, a gelling inhibitor and an organic solvent. it can.

The main component of the aqueous resin composition containing the aqueous solution or aqueous dispersion of the acrylic copolymer (A) and the urethane dispersion (B) of the present invention is an aqueous solution or aqueous dispersion of the acrylic copolymer (A). Urethane dispersion (B) was added to the mixture, and 500 to 1000 r using a dissolver.
It can be manufactured by stirring and mixing at pm for 5 to 10 minutes. Further, when a self-emulsifying polyisocyanate (C) as a curing agent is blended with a main component of an aqueous resin composition containing an aqueous solution or aqueous dispersion (A) of an acrylic copolymer and a urethane dispersion (B), From the viewpoint of the pot life and the like, it is preferable to mix them both immediately before use as a paint.

When the self-emulsifying polyisocyanate is blended with the main component, the NCO content in the self-emulsifying polyisocyanate is preferably 5 to 18% by weight.
The self-emulsifying type polyisocyanate may be used after being diluted with an organic solvent. The content of the organic solvent is preferably in the range of 0 to 30% by weight. When workability and finishability as a water-based paint are emphasized, propylene glycol methyl ether acetate, diethylene glycol diethyl ether, dipropylene glycol dimethyl ether, a dimethyl ester mixture of glutaric acid, succinic acid, and adipic acid (trade name) : DBE, manufactured by DuPont) or the like. Among them, it is particularly preferable to use propylene glycol methyl ether acetate from the viewpoint that the curing agent can be easily mixed with the main component and the curing agent itself can be easily dispersed in water.

The coating composition of the present invention is excellent in adhesion, extensibility (prevention of cracking) and stain resistance, which have been difficult with conventional water-based resins. Can be used as a top coat for waterproofing materials such as verandas and rooftops, particularly urethane waterproofing materials, which require the application of water.

[0035]

EXAMPLES Hereinafter, the present invention will be described more specifically, but the present invention is not limited to these examples.

<Production of acrylic copolymer> In 500 g of methyl ethyl ketone, each monomer was adjusted so that the solid content of the monomer was about 50% (so that the total amount of the monomers was about 500 g). The monomers were added in the composition shown in Table 1, and solution radical polymerization was performed at 80 ° C. for 6 hours using 5 g of AIBN as an initiator. After the completion of the polymerization reaction, the carboxylic acid present in the obtained polymer was neutralized with dimethylmonoethanolamine (DMEA, manufactured by Nippon Emulsifier Co., Ltd.) in the amount shown in Table 1. Subsequently, the polymer solution was dispersed in pure water in the amount shown in Table 1 and uniformly dispersed. Thereafter, methyl ethyl ketone was removed by distillation under reduced pressure, and an aqueous dispersion of an acrylic copolymer (A-
1) to (A-4) were obtained. Table 1 shows the composition and physical properties of the aqueous dispersion of the obtained acrylic copolymer.

[0037]

[Table 1] MMA: Methyl methacrylate (Mitsubishi Gas Chemical Co., Ltd.)
EA: Ethyl acrylate (Toa Gosei Chemical Co., Ltd.) n-BA: n-butyl acrylate (Toa Gosei Chemical Co., Ltd.) AA: Acrylic acid (Nippon Shokubai Co., Ltd.) HEMA: Hydroxyethyl methacrylate ( *: The particle size of the acrylic copolymer in the aqueous dispersion is as follows:
It measured using the particle size measuring device ELS-8000 (made by Otsuka Electronics Co., Ltd.). **: Mw of the acrylic copolymer is GPC (column:
HLC-8120 (manufactured by Tosoh Corporation), carrier: tetrahydrofuran, standard sample: polystyrene).

<Manufacture of urethane dispersion> Table 2
The urethane reaction of diisocyanate, glycol and dimethylolbutanoic acid was carried out in methyl ethyl ketone according to the composition shown in (1). Next, 3.0 g of triethylamine was added to the obtained prepolymer to neutralize it, and further, diamine, monoethanolamine and deionized water were added and dispersed in water. Thereafter, methyl ethyl ketone was removed by distillation under reduced pressure, and the urethane dispersion (B-
1) to (B-4) were obtained. Table 2 shows the composition and physical properties of the obtained urethane dispersion.

[0039]

[Table 2] IPDI: isophorone diisocyanate (manufactured by Huls) HDI: hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd.) P-2000: polypropylene glycol (manufactured by Asahi Denka Kogyo Co., Ltd.) Mw = 2000 PTG-2000SN: polytetramethylene ether glycol ( Mw = 2000 Hexane adipate: (Nippon Polyurethane Industry Co., Ltd.)
Mw = 2000 PTGL-2000: Modified polytetramethylene ether glycol (manufactured by Hodogaya Chemical Industry Co., Ltd.) Mw = 2000 IPDA: Isophoronediamine (manufactured by Huls) HDA: Hexanediamine (manufactured by Kanto Chemical Co., Ltd.) *: The particle size of the polyurethane in the dispersion can be measured with a particle size analyzer ELS-8000 (Otsuka Electronics Co., Ltd.)
Was used for the measurement. **: Mw of polyurethane is GPC (column: HL
C-8120 (manufactured by Tosoh Corporation), carrier: tetrahydrofuran, standard sample: polystyrene).

<Production of Top Coating Paint> According to the composition shown in Table 3, a white paint, that is, a white aqueous resin composition (R-1) was produced by the following method. First, urethane dispersion 2 was added to 42.8 parts by weight of the acrylic resin aqueous dispersion.
4.5 parts by weight were added and mixed with a dissolver (Nippon Tokushu Kika Kogyo Co., Ltd.) to obtain an acrylic / urethane mixed dispersion (solid content ratio: 7/3). Apart from this, 1
To 4.9 parts by weight of deionized water, 1.0 part by weight of a dispersant was added, and while stirring with a dissolver, 1 part of titanium oxide was added thereto.
4.5 parts by weight were gradually added to prepare a mill base. The obtained mill base was further dispersed by a sand mill to obtain a titanium oxide paste. Next, 30.4 parts by weight of a titanium oxide paste was added to 67.3 parts by weight of the acrylic / urethane mixed dispersion, and further 0.5 parts by weight of an antifoaming agent, 0.8 parts by weight of a leveling agent, and other additives. 1.0 part by weight of the agent, and stirred with a dissolver to obtain a white aqueous resin composition (R
-1). The properties of the obtained paint were evaluated by the following methods.

[Solid Content] In accordance with JIS K54074, 2 g of a sample was precisely weighed, and a residue obtained by heating to remove an evaporated component was determined as a percentage in the sample to obtain a solid content.

[Viscosity] According to JIS K5400,
It measured using the B type rotational viscometer of Tokyo Keiki Co., Ltd. The measurement temperature was 25 ° C ± 0.5 ° C.

[PVC (Pigment Volume Concentration)] PVC was calculated based on the following equation.

The white aqueous resin compositions (R-2) to (R-) were prepared in the same manner as in Example 1 except that the formulations shown in Table 3 were used.
8) was prepared and evaluated in the same manner as in the white aqueous resin composition (R-1).

[0045]

[Table 3]

<Production of Top Coating Composition> (Example 1) The white water-based resin composition (R-) was prepared such that the ratio of the active hydrogen concentration of the white water-based resin composition to the isocyanate concentration of the curing agent was 1. 1) Self-emulsifying polyisocyanate (AQ)
-200, manufactured by Nippon Polyurethane Co., Ltd.) and mixed well. The performance of the obtained top coat was measured according to the following method. Table 4 shows the measurement results.

(Examples 2 to 6, Comparative Examples 1 and 2) A top coat was produced in the same manner as in Example 1 except that the composition of the top coat was changed as shown in Table 4. In Examples 2 to 6 and Comparative Examples 1 and 2, the compounds were blended such that the ratio between the active hydrogen concentration of the aqueous resin composition and the isocyanate concentration of the curing agent was 1. The performance of the obtained top coat was measured according to the following method. Table 4 shows the measurement results.

(Comparative Example 3) Instead of the aqueous resin composition,
200 g of an acrylic dispersion having a hydroxyl value of 140 (mgKOH / g, solid) was used, and a self-emulsifying polyisocyanate (AQ-20) was used as a curing agent.
0, manufactured by Nippon Polyurethane Co., Ltd.), mixed well, and then applied and cured on a urethane waterproofing material. In this case as well, the ratio between the active hydrogen concentration of the acrylic dispersion and the isocyanate concentration of the curing agent was 1%.
I am trying to be. The performance of the obtained top coat
It was measured according to the following method. Table 4 shows the measurement results.

(Comparative Example 4) Instead of a two-pack type top coat obtained by mixing a curing agent with an aqueous resin composition, a one-pack type acrylic emulsion was used.
It was measured according to the following method. Table 4 shows the measurement results.

[Working time] The term "working time" as used herein means the time from when a curing agent is added to an aqueous resin composition (base resin) until it can no longer be applied as a topcoat paint. The pot life was determined from the relationship. In other words, when a paint that has passed the pot life is used, the physical properties of the resulting coating film are reduced.After blending the curing agent with the main agent, coating films are prepared at regular intervals, and in a tensile test of the coating film. The point at which the reduction in the elongation and strength of the coating film was observed was defined as the pot life.

[Touch dryness (tack free time)] 2
At 0 ° C., a top coat was applied on the urethane waterproofing material, and a fingertip was brought into contact with the surface of the coating at regular intervals immediately after the application. Then, a time (minute) from immediately after the application until the coating film did not adhere to the fingertip was obtained.

[Crack resistance of coating film during initial drying] Crack resistance of the coating film during initial drying was observed in accordance with JIS A 6909 7.9. The flexible plate having a thickness of 4mm (300 × 150mm) smeared urethane waterproof material in an amount of ^{1.5kg / m 2, 20 ℃,} 65%
After curing at RH for 3 days, 0.15kg of top coat
/ M ² was applied to prepare a test piece. The test piece immediately after the top coat was applied was placed in a wind tunnel adjusted to a wind speed of 3 m / sec ± 10%. After 6 hours, the test piece was taken out, and the occurrence of cracks on the coating film surface was visually observed. The crack resistance of the coating film was evaluated according to the following three grades depending on the presence or absence of cracks. ：: No cracks are observed at all △: Small cracks are observed at the thick film portion ×: Large cracks are observed at the thick film portion

[Adhesion Strength] A urethane waterproofing material aged at 20 ° C. and 65% RH for 3 days was coated with a top coat of 0.1 g.
It was applied in an amount of 15 kg / m ² and was cured at 20 ° C. and 65% RH for one week. A non-woven fabric impregnated with the top coat is further laminated on the cured top coat to form three layers,
Cured at 65 ° C. and 65% RH for 1 week. After curing, JIS
A peeling test was performed according to K6301, and the adhesion strength (N / mm) of the topcoat paint to the urethane waterproofing material was determined.

[0054] laying a release sheet on the bottom plate made of [elongation] synthetic resin, pouring a waterproof material on the at 1.5 kg / m ^2, 2
Cured for 3 days at 0 ° C. and 65% RH. Furthermore, a top coat is applied on this waterproof material, and the temperature is 25 ° C and 65% R.
After curing and curing with H for one week, the sample was cut out with a dumbbell-shaped No. 2 shape to obtain a test piece. Using a tensile tester (Autograph, Shimadzu Corporation), the marked line 2 on the obtained test piece
The elongation rate between cm was measured.

[Degradation during Elongation] A release paper was laid on a bottom plate made of synthetic resin, a waterproof material was poured at 1.5 kg / m ² thereon, and cured at 20 ° C. and 65% RH for 3 days. Furthermore, a top coat is applied on this waterproof material,
After curing and curing at 5% RH for one week, the test piece was cut out with a dumbbell-shaped No. 1 shape to obtain a test piece. A deterioration test during elongation of the test piece was measured in accordance with JIS A6909 7.32. That is, the mark 40 mm on the test piece is 60 mm
The test piece is stretched until reaching 20 ° C. and 65% RH for 24 hours.
The sample was allowed to stand in a curing room for an hour, and was further left vertically at 80 ° C. ± 2 ° C. for 7 days. For the test piece after standing for 7 days, the top coat was visually observed for peeling, warping and twisting,
The evaluation was made in three stages of ○, Δ and × as follows. ：: no cracks were observed in the top coat film △: small cracks were slightly observed ×: cracks were significantly observed

[Initial gloss] JIS K5400 7.6
The initial gloss value (60 ° gloss) of the surface of the coating film was determined according to the method for measuring specular glossiness described above. For the measurement of the initial gloss value, a gloss meter manufactured by Nippon Denshoku Industries Co., Ltd. was used.

[Accelerated Weathering Resistance] After a urethane waterproofing material was applied on a slate plate and cured for a certain period of time, an overcoat was further applied and cured at 20 ° C. and 65% RH for 14 days. The accelerated deterioration test of the obtained specimen was performed according to JIS.
The measurement was performed using a sunshine weather meter (SWOM) according to K5400. As test conditions for accelerated deterioration, the temperature in the tank was adjusted to 63 ± 3 ° C. using a black panel thermometer, and the water injection time in one cycle (120 minutes) was 18 minutes. The gloss value (60 °) of the coating film after 500 hours, 1000 hours, and 1500 hours of irradiation time was measured using a gloss meter of Nippon Denshoku Industries Co., Ltd., and the gloss value relative to the initial gloss value of the coating film was measured. The retention was determined. It can be said that the higher the gloss retention, the better the weather resistance.

[Contamination] After applying a urethane waterproofing material on a slate plate and curing it for a certain period of time, an overcoat was further applied and cured at 20 ° C. and 65% RH for 14 days. The obtained test body was horizontally set in an outdoor exposure test site for 6 months. The outdoor exposure time is from 30 minutes after sunrise to 30 minutes before sunset, and the test specimen has no ground-based properties that hinder direct sunlight, ventilation, and precipitation.
Installed in a place with low environmental pollution factors such as toxic gas and steam. Further, the outdoor exposure test site was treated so as not to be lit by the sun, dust soared, or flooded. The whiteness of the test sample after 6 months of outdoor exposure was measured using a color difference meter (Nippon Denshoku Industries Co., Ltd.), and the difference ΔL from the initial whiteness of the test sample was determined. The contamination was evaluated at each stage. ○; ΔL ≦ 5 △; 5 <ΔL <10 ×; 10 ≦ ΔL

[Water resistance] Urethane waterproofing material test piece (150
(× 70 × 2 mm) was prepared and cured, and then a top coat was applied and cured at 14 ° C. for 14 days in a standard condition of 20 ° C. and 65% RH to obtain a test piece. The obtained test piece was immersed in water at 20 ° C. for 7 days. After immersion, the test pieces were observed immediately after being taken out and after leaving for 2 hours after being taken out. The presence or absence of whitening, blistering, cracking, clouding, wrinkles, etc. in the coating film after immersion was compared with the test sample coating film before immersion. In addition, the thing which does not show a big change in the coating state of a test piece before and after immersion was set to "no abnormality".

[Alkali Resistance] A test piece identical to the test piece used for the evaluation of water resistance was prepared, and this test piece was immersed in a solution of sodium carbonate adjusted to 5 w / v% with deionized water for 7 days. Was. After immersion, the test piece immediately after taking out and after leaving for 2 hours after taking out, the blistering, cracking,
Peeling and presence of holes were visually observed. In addition, the thing which does not show a big change in the coating state of a test piece before and after immersion was set to "no abnormality".

[Acid Resistance] A test piece identical to the test piece used for the evaluation of water resistance was prepared, and sulfuric acid was removed with deionized water at 5 w / v%.
This test piece was immersed for 7 days in the liquid adjusted to 1). After immersion, the test pieces immediately after being taken out and left for 2 hours after being taken out were visually inspected for swelling, cracking, peeling, and presence or absence of holes. In addition, the thing which does not show a big change in the coating state of a test piece before and after immersion was set to "no abnormality".

[Abrasion resistance] JIS K5400 8.9
Using a Taber-type abrasion tester, the degree of abrasion of the coating film was expressed as abrasion loss. The abrasion loss was determined by performing a test on three test pieces, calculating by the following formula, and setting the average value. W = (A−B) × R / N W: loss of wear per prescribed number of revolutions (mg) A: mass of test specimen before test (mg) B: mass of test specimen after test (mg) R: prescribed Rotation speed N: Test rotation speed

[Table 4]

[0063]

The overcoating composition of the present invention is water-based, and therefore, in terms of protecting the global environment and ensuring work safety, compared with the organic solvent-based overcoating which has been generally used in the past. It is very good.

Further, the coating film comprising the top coating composition of the present invention is superior in adhesion to a waterproof material as a base material and has sufficient extensibility as a coating film as compared with a conventional water-based top coating material. In addition, the coating film does not crack. Furthermore, the coating film obtained from the two-pack type top coating composition of the present invention is excellent in abrasion resistance, stain resistance, water resistance and weather resistance. Therefore, the use of the two-pack water-based topcoat composition of the present invention can sufficiently protect the waterproofing material and also provide the waterproofing material with cosmetics.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuya Sugimoto 4-1-10- 506 Sakurada, Washinomiya-cho, Kita-Katsushika-gun, Saitama Prefecture (72) Inventor Kazuyoshi Nomura 1-1-12, Mutsucho, Kazo City, Saitama Prefecture Inventor Yutaka Miyata 1-9-8 Kurihara, Kuki-shi, Saitama F-term (reference) 4J038 CG011 CG141 CH031 CH041 CH071 CH121 CH171 DB221 DG132 DG262 GA03 GA06 KA03 MA08 MA10 MA13 MA14 NA01 NA04 NA12 PA07 PB05 PC04

Claims (1)

[Claims] 1. An aqueous resin composition containing an aqueous solution or aqueous dispersion of an acrylic copolymer (A) and a urethane dispersion (B) in an amount of 5 to 40% by weight (solid content ratio) based on (A). Two-part water-based topcoat composition obtained by blending a self-emulsifying polyisocyanate (C) with the above.