JP7315056B1 - Top coat composition for waterproofing urethane coating - Google Patents

Abstract

[PROBLEMS] To provide a topcoat composition for waterproofing a urethane coating film, which has good extensibility and weatherability and provides a topcoat with a matte finish. SOLUTION: It consists of (A1) a main agent and (A2) a curing agent, wherein (A1) contains (a) 100 parts by mass of acrylic polyol (solid content) and (b) 20 to 60 parts by mass of SiO-containing inorganic particles, (b) contains at least one inorganic particle having an average particle diameter of 20 μm or less in an amount of 20 parts by mass or more per 100 parts by mass (solid content) of (a), and (A2) contains (c) a polyisocyanate. , (c) contains at least one urethane prepolymer which is a reaction product of (d) a polyisocyanate containing two or more NCO groups in one molecule and a polyol having a molecular weight of 400 to 3,000, and (A2) The ratio (solid content) of (d) in is 70% by mass or more, the mass ratio (solid content) of (a) and (c) is 80/20 to 30/70, and [NCO]/[OH] is 0.5. -2.0. [Selection figure] None

Description

The present invention relates to a topcoat composition for waterproofing urethane coatings.

Conventionally, the coating film waterproofing method has been widely used as a waterproofing method for roofs of buildings, balconies, balconies, open corridors, and the like.
In this construction method, a primer layer is formed on the surface of a base material such as concrete or mortar, a urethane-based waterproof material layer is formed thereon, and a topcoat layer is further formed thereon to form a multi-layer waterproof structure.

In this case, the top coat is applied for the purpose of protecting the urethane-based waterproof material layer and improving its appearance, and an acrylic urethane-based paint is widely used (see Patent Documents 1 to 3). In order to protect the waterproof material layer over a long period of time, the extensibility of the top coat is important from the viewpoint of following the behavior of the underlying layer and ensuring reliable waterproof performance.

In addition, in recent years, in the interior and exterior walls of buildings, etc., there is an increasing demand for a so-called matte finish with low gloss, and from the viewpoint of harmony with matte finished exterior walls, etc., urethane coating waterproof top coats are also required to have a matte finish.
In this regard, for example, Patent Document 4 discloses that a water-based resin composition containing a predetermined amount of a predetermined water-based resin, a predetermined composition of a pigment, and a glycol ether compound provides a matte coating film excellent in stain resistance, weather resistance and substrate conformability, but there is room for improvement in terms of stretchability and weather resistance as a top coat.

Japanese Patent Application Laid-Open No. 2002-309156 Japanese Patent Application Laid-Open No. 2004-263121 JP-A-2007-720 JP 2016-40349 A

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a topcoat composition for waterproofing a urethane coating film that has good extensibility and weather resistance and provides a topcoat with a matte finish.

The inventors of the present invention have made intensive studies to achieve the above object, and as a result, found that a two-component composition obtained by mixing a base material containing a predetermined ratio of an acrylic polyol and SiO ₂ -containing inorganic particles having a predetermined average particle size with a curing agent containing a predetermined urethane prepolymer is suitable as a topcoat for waterproofing a urethane coating film because it gives a matte finish coating film and has good extensibility and weather resistance, and thus completed the present invention.

That is, the present invention
1. A two-component urethane coating waterproof topcoat composition comprising (A1) a main agent and (A2) a curing agent,
The (A1) main agent contains (a) an acrylic polyol and (b) SiO ₂ -containing inorganic particles, and 20 to 60 parts by mass of the (b) SiO ₂ -containing inorganic particles per 100 parts by mass (solid content) of the (a) acrylic polyol,
The (b ₎ SiO ₂ -containing inorganic particles contain at least one type of SiO 2 -containing inorganic particles having an average particle size of 20 μm or less, and 20 parts by mass or more of the SiO ₂ -containing inorganic particles having an average particle size of 20 μm or less per 100 parts by mass (solid content) of the (a) acrylic polyol,
The (A2) curing agent contains (c) a polyisocyanate, and the polyisocyanate (c) contains at least one urethane prepolymer which is a reaction product of (d) a polyisocyanate containing two or more isocyanate groups in one molecule and a polyol having a molecular weight of 400 to 3,000,
The ratio (solid content) of the (d) urethane prepolymer in the (A2) curing agent is 70% by mass or more,
A two-component urethane coating waterproofing topcoat coating composition characterized in that the mass ratio (solid content) of (a) acrylic polyol and (c) polyisocyanate is 80/20 to 30/70, and the reaction molar ratio ([NCO]/[OH]) is 0.5 to 2.0,
2. 1. 2-liquid type urethane coating waterproofing topcoat paint composition, wherein the (b) SiO ₂ -containing inorganic particles include at least one type of SiO ₂ -containing inorganic particles having an average particle diameter of 10 μm or less, and 20 parts by mass or more of the SiO ₂ -containing inorganic particles having an average particle diameter of 10 μm or less per 100 parts by mass (solid content) of the (a) acrylic polyol;
3. A 1- or 2-pack urethane coating waterproof topcoat coating composition is provided in which the mass ratio (solid content) of (a) acrylic polyol and (c) polyisocyanate is 75/25 to 35/65.

By using the two-liquid type urethane coating film waterproofing topcoat composition of the present invention, it is possible to produce a topcoat having good stretchability and weather resistance and a matte finish.

The present invention will be described in more detail below.
本発明に係る２液型ウレタン塗膜防水用トップコート組成物は、（Ａ１）主剤と（Ａ２）硬化剤とからなり、（Ａ１）主剤が、（ａ）アクリルポリオールおよび（ｂ）含ＳｉＯ ₂無機粒子を含有し、（ａ）アクリルポリオール１００質量部（固形分）に対して（ｂ）含ＳｉＯ ₂無機粒子が２０～６０質量部含まれ、（ｂ）含ＳｉＯ ₂無機粒子が、平均粒子径２０μｍ以下の含ＳｉＯ ₂無機粒子を少なくとも１種含み、（ａ）アクリルポリオール１００質量部（固形分）に対し、平均粒子径２０μｍ以下の含ＳｉＯ ₂無機粒子が２０質量部以上含まれ、（Ａ２）硬化剤が、（ｃ）ポリイソシアネートを含有し、当該ポリイソシアネート（ｃ）が、（ｄ）１分子中に２個以上のイソシアネート基を含むポリイソシアネートと、分子量４００～３，０００のポリオールとの反応物であるウレタンプレポリマーを少なくとも１種含み、（Ａ２）硬化剤における（ｄ）ウレタンプレポリマーの割合（固形分）が、７０質量％以上であり、（ａ）アクリルポリオールと（ｃ）ポリイソシアネートとの質量比（固形分）が、８０／２０～３０／７０であり、反応モル比（［ＮＣＯ］／［ＯＨ］）が０．５～２．０であることを特徴とする。

(1) Component (A1) Component (A1) is the main ingredient of the present composition and comprises (a) acrylic polyol and (b) SiO ₂ -containing inorganic particles.
In the present invention, various acrylic polyols obtained by radical copolymerization of an acrylic monomer having a hydroxyl group and other polymerizable monomers having an unsaturated double bond can be used as the acrylic polyol of the component (a).

Specific examples of acrylic monomers having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, N-methylolated acrylamide, ε-caprolactone-modified hydroxy (meth) acrylate, and carbonate-modified methacrylate (manufactured by Daicel Chemical Industries, Ltd., HEMAC). These may be used individually by 1 type, or may be used in combination of 2 or more type.

Specific examples of polymerizable monomers having unsaturated double bonds include carboxylic acid group-containing monomers such as (meth)acrylic acid, maleic acid, fumaric acid and itaconic acid; epoxy group-containing monomers such as glycidyl (meth)acrylate; amino group-containing monomers such as N,N-dimethylaminoethyl (meth)acrylate and N,N-diethylaminoethyl (meth)acrylate; C1-C24 alkyl (meth)acrylate monomers such as t-butyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decanyl (meth)acrylate, undecanyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate; aromatics such as styrene, α-methylstyrene, and vinyltoluene Examples thereof include hydrocarbon-based monomers, vinyl ether-based monomers such as methyl vinyl ether and ethyl vinyl ether, vinyl acetate, vinyl propionate, (meth)acrylonitrile, N-vinylpyrrolidone, and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type. In particular, it is preferable to use an alkyl (meth)acrylate monomer as the polymerizable monomer having an unsaturated double bond.

The radical copolymerization is carried out using a polymerization initiator in the absence of solvent or in the presence of a suitable organic solvent.
The organic solvent is not particularly limited as long as it does not adversely affect the reaction. Specific examples thereof include aliphatic or alicyclic hydrocarbons such as n-hexane, n-heptane, n-octane, cyclohexane, and cyclopentane; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, low-boiling aromatic naphtha, and high-boiling aromatic naphtha; Methanol, ethanol, iso-propanol, n-butanol, iso-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-butyl ether, propylene glycol monomethyl ether, propylene glycol mono-n-propyl ether, diethylene glycol monobutyl ether, etc.; ketones such as isobutyl ketone, methyl n-amyl ketone, cyclohexanone; ethers such as dimethoxyethane, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol dibutyl ether; N-methylpyrrolidone, dimethylformamide, dimethylacetamide, ethylene carbonate and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.

The polymerization initiator can be appropriately selected from known radical polymerization initiators, and examples thereof include 2,2'-azobisisobutyronitrile, azobisisovaleronitrile, benzoyl peroxide, t-butyl peroxide, cumene hydroperoxide and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.
The reaction temperature is usually about 60 to 150°C. The reaction time is usually about 1 to 12 hours.

In addition, acrylic polyol can also use a commercial item. Specific examples thereof include Excelol 290, Excelol 170, NX84-1 (manufactured by Asia Industry Co., Ltd.), Acrydic A-801-P, Acrydic A-823 (manufactured by DIC Corporation) and the like, but are not limited thereto.

On the other hand, in the present invention, the SiO ₂ -containing inorganic particles of the component (b) contain at least one type of SiO ₂ -containing inorganic particles having an average particle diameter of 20 μm or less, preferably 10 μm or less. By using 20 parts by mass or more of the particles having an average particle diameter within the above range, the specular glossiness of the resulting topcoat can be reduced. again. Although the lower limit of the average particle size is not particularly limited, it is preferably 1 µm or more, more preferably 2 µm or more, still more preferably 3 µm or more, and even more preferably 4 µm or more. The average particle size in the present invention is the volume average particle size (d ₅₀ ) by laser diffraction method.

Examples of SiO ₂ -containing inorganic particles include silica, diatomaceous earth, talc, kaolin and the like, and these may be commercially available products. Moreover, the inorganic particles may be subjected to general surface treatment.
Examples of commercially available silica include ACEMATT (registered trademark) OK412, OK500, OK520, OK607, 3300, 3600, 82, HK125, HK400, HK440, 790, 810, TS100, EXP3400, etc., which are silica particles manufactured by Evonik Japan Co., Ltd., but are not limited thereto.
Examples of commercially available diatomaceous earth include Radiolite 600, 700, 900, 2000, and 3000, which are flux-calcined diatomaceous earths manufactured by Hayashi Kasei Co., Ltd.; Radiolite 100, 200, 300, 500, and 800, which are calcined diatomaceous earths manufactured by Hayashi Kasei Co., Ltd.; Sparkle Flow; and Special Flow.
Commercially available talc products include, but are not limited to, Talcan Powder (registered trademark) PK-S, PK-C, PK-P, Micron White (registered trademark) #5000S and #5000R manufactured by Hayashi Kasei Co., Ltd.
Commercially available kaolin products include, but are not limited to, Satintone 5HB, SP-33, W, Translink 37, 77, 445, etc., which are calcined kaolins manufactured by BASF Corporation.

In component (A1), component (b) is contained in an amount of 20 to 60 parts by mass, preferably 25 to 55 parts by mass, per 100 parts by mass (solid content) of component (a). If the content of the component (b) is within the above range, the resulting top coat will have good extensibility, weather resistance and mattness.

(2) Component (A2) Component (A2) is a curing agent for the present composition and contains (c) polyisocyanate.
In the present invention, the component (c) polyisocyanate contains at least one urethane prepolymer which is a reaction product of (d) a polyisocyanate containing two or more isocyanate groups in one molecule and a polyol having a molecular weight of 400 to 3,000.

The polyisocyanate containing two or more isocyanate groups in one molecule, which is a raw material for the component (d), can be appropriately selected and used from known ones.

Aliphatic polyisocyanates include hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate and trioxyethylene diisocyanate.

Alicyclic polyisocyanates include isophorone diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate and the like.

Aromatic polyisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2,2′-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-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate and the like.
Examples of araliphatic polyisocyanates include xylylene-1,4-diisocyanate and xylylene-1,3-diisocyanate.

These isocyanates may be used individually by 1 type, or may be used in combination of 2 or more type. In addition, their adducts, allophanates, dimers, trimers and the like may also be used.

In particular, the polyisocyanate used in the present invention is preferably a polyisocyanate containing at least one dimer selected from the group consisting of aliphatic isocyanates and alicyclic isocyanates, preferably at least 30% by mass, preferably at least 35% by mass, more preferably at least 45% by mass, and even more preferably at least 50% by mass of a dimer of hexamethylene diisocyanate, and containing two or more isocyanate groups in one molecule. Although the upper limit of the dimer content is not particularly limited, it is usually 70% by mass or less.

In the present invention, the number of isocyanate groups possessed by the polyisocyanate is set to 2 or more per molecule from the viewpoint of improving the extensibility of the resulting topcoat, but 2 to 4 groups are preferable, and 2 to 3 groups are more preferable from the viewpoint of suppressing gelation during reaction with a polyol and improving handleability during use.
Although the viscosity of the polyisocyanate is not particularly limited, it is preferably from 50 to 900 mPa·s, more preferably from 100 to 700 mPa·s at 25° C. in consideration of handling properties during use. The viscosity is a value measured by a Brookfield viscometer.

A commercial item can also be used as a polyisocyanate and its dimer body. Specific examples thereof include EXCELHARDENER X-19 (manufactured by Asia Industry Co., Ltd., aliphatic dimer-containing polyisocyanate), Coronate 2365 (manufactured by Tosoh Corporation), and Desumodur N 3400 (manufactured by Sumika Covestro Urethane Co., Ltd.).

The polyol, which is the other raw material of component (d), is not particularly limited as long as it has a molecular weight of 400 to 3,000, and can be appropriately selected from known polyols. Specific examples thereof include polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol and the like.
The above molecular weight is a polystyrene-equivalent number-average molecular weight measured by gel permeation chromatography (hereinafter abbreviated as GPC) with differential refractometer detection.

Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymers thereof, which are obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc. using low-molecular-weight polyols, low-molecular-weight polyamines, and low-molecular-weight aminoalcohols as initiators.

Polyester polyols include one or more of polycarboxylic acids, acid esters, or acid anhydrides such as succinic acid, adipic acid, sebacic acid, azelaic acid, terephthalic acid, isophthalic acid, orthophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hexahydroorthophthalic acid, naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and trimetic acid, and ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, trimethylolpropane, glycerin, polyol obtained by dehydration condensation with one or more of low-molecular-weight polyols such as pentaerythritol.

Polycaprolactone polyols include polyols obtained by ring-opening polymerization of cyclic ester monomers such as ε-caprolactone and γ-valerolactone using low-molecular-weight polyols, low-molecular-weight polyamines and low-molecular-weight aminoalcohols as initiators.

Examples of polycarbonate polyols include polyols obtained by reacting the above low-molecular-weight polyols with ethylene carbonate, diethyl carbonate, diphenyl carbonate, or the like.

In the present invention, among these, polyether polyols capable of providing a top coat having excellent extensibility are preferred, and polypropylene glycol is preferred.

The average number of functional groups of the polyol used in the present invention is not particularly limited, but from the viewpoint of improving the extensibility of the resulting top coat, it is preferably 2.2 or more, and considering suppression of gelation during reaction with polyisocyanate and good compatibility with the main agent, 2.2 to 4 is more preferable, and 2.2 to 3 is even more preferable.

A commercial item can also be used for the polyol used by this invention. Specific examples thereof include Sannics GP-400 (manufactured by Sanyo Kasei Co., Ltd.), Sannics GP-1000 (manufactured by Sanyo Kasei Co., Ltd.), Sannics GP-3000 (manufactured by Sanyo Kasei Co., Ltd.), Kuraray Polyol F-1010 (manufactured by Kuraray Co., Ltd.), Polylite OD-X-2588 (manufactured by DIC Corporation), PCP-100L (Tosoh Co., Ltd.) and the like.

The urethane prepolymer of component (d) can be obtained by reacting the above-described polyisocyanate and polyol in the presence or absence of a solvent.
The reaction conditions between the polyisocyanate and the polyol are not particularly limited. For example, if necessary, in the presence of a known urethanization catalyst such as dibutyltin laurate and dioctyltin laurate, an excess amount of polyisocyanate and polyol are reacted at 20 to 150°C.

At this time, the reaction molar ratio ([NCO]/[OH]) between the [NCO] of the polyisocyanate and the [OH] of the polyol is preferably 1.05 or more from the viewpoint of significantly improving the extensibility of the resulting topcoat, and more preferably 1.5 or more, and even more preferably 2.0 or more in consideration of handleability during use. Although the upper limit of the reaction molar ratio is not particularly limited, it is preferably 7.0 or less, more preferably 6.0 or less.

When a solvent is used, it is not particularly limited as long as it does not adversely affect the reaction.

The isocyanate content (solid content) of the obtained (d) urethane prepolymer is preferably 0.5 to 12.0% by mass, more preferably 2.0 to 9.0% by mass, and even more preferably 3.0 to 7.0% by mass, in consideration of improving the extensibility of the resulting topcoat.

The solid content concentration of the obtained (d) urethane prepolymer is preferably 5 to 50% by mass, more preferably 15 to 40% by mass, from the viewpoint of storage stability.

In the present invention, the ratio (solid content) of the (d) urethane prepolymer in the (A2) component is set to 70% by mass or more from the viewpoint of the extensibility of the resulting top coat, etc., preferably 75% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass, and even more preferably 1000% by mass.

When the urethane prepolymer (d) is used in an amount of 70% by mass or more and less than 100% by mass, another polyisocyanate is used in combination.
Other polyisocyanates include the above-described aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, their adducts, allophanates, dimers and trimers (these are collectively referred to as modified products.) and reaction products (urethane prepolymers) of these polyisocyanates with polyols having a molecular weight outside the range defined in the present invention, but aliphatic polyisocyanate modified products and alicyclic polyisocyanate modified products are preferred.
Moreover, a commercial item can be used as another polyisocyanate. Specific examples thereof include Takenate D-127A (manufactured by Mitsui Chemicals, Inc., H6XDI isocyanurate modified), Desmodur XP 2565 (manufactured by Sumika Bayer Urethane Co., Ltd., IPDI allophanate modified), Takenate D-140N (manufactured by Mitsui Chemicals, Inc., IPDI adduct modified), Stabio D-370N (manufactured by Mitsui Chemicals, Inc., PDI isocyanurate), Coronate 27. 70 (manufactured by Tosoh Corporation, modified HDI allophanate), Coronate 2612 (manufactured by Tosoh Corporation, modified HDI adduct), and the like.

In the two-component urethane coating waterproofing topcoat composition of the present invention, the blending ratio of (A1) main agent and (A2) crosslinking agent is such that the mass ratio (solid content) of (a) acrylic polyol and (c) polyisocyanate is (a)/(c) = 80/20 to 30/70, and the reaction molar ratio ([NCO]/[OH]) is 0.5 to 2.0, from the viewpoint of increasing the crosslink density and sufficiently exhibiting the coating film performance of the topcoat. However, (a)/(c) is preferably 75/25 to 35/65, more preferably 70/30 to 40/60, even more preferably 60/40 to 45/55, and [NCO]/[OH] is preferably 0.6 to 1.9, even more preferably 0.7 to 1.8.

If necessary, an organic solvent may be added to the two-liquid type urethane coating film waterproofing topcoat composition of the present invention. As the organic solvent, various solvents conventionally used in topcoat compositions can be used. Specific examples thereof include aromatic hydrocarbon solvents such as toluene and xylene; ester solvents such as ethyl acetate, n-butyl acetate and n-amyl acetate; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane; , propylene glycol monomethyl ether propionate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, glycol ether ester solvents and the like. These may be used individually by 1 type, or may be used in combination of 2 or more type.

In addition, if necessary, the two-component urethane coating film waterproofing topcoat composition of the present invention may contain various additives such as coloring pigments such as titanium oxide, extender pigments, surface conditioners, defoaming agents, thickeners, anti-settling agents, ultraviolet absorbers, light stabilizers, and catalysts.
These solvents and various additives may be blended in either one of (A1) the main agent and (A2) the curing agent, or in both.

The two-component urethane coating film waterproofing topcoat composition of the present invention can be suitably used as a two-component room-temperature-curable composition in which the two components are prepared on site and applied.
In this case, the coating method is not particularly limited, and may be appropriately selected from known methods such as brush coating and roller coating. Also, the amount of coating, the thickness of the coating film, the drying time, etc. may be appropriately set according to the type of the urethane waterproofing material.

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following description, "parts" means "mass parts" and "%" means "% by mass".

[Example 1]
（１）（Ａ１）主剤の調製 アクリルポリオール（ＮＸ８４－１、亜細亜工業（株）製、水酸基価＝２２．０ｍｇＫＯＨ／ｇ、固形分５２．５％、以下同様）１９０．０部、シリカ粒子（ＡＣＥＭＡＴＴ（登録商標） ＯＫ４１２、エボニックジャパン（株）製、平均粒子径ｄ ₅₀ ＝６．３μｍ、以下同様）４０．０部、酸化チタン粒子（ＣＲ－９５、石原産業（株）製、以下同様）１３５．４部、キシレン２３４．６部、およびガラスビーズ６００部を混合容器に仕込み、ペイントシェーカーで１時間分散を行い、主剤を得た。
(2) (A2) Preparation of Curing Agent In a reactor equipped with a stirrer, thermometer, cooling pipe and nitrogen gas inlet pipe, 40.0 parts of aliphatic dimer-containing polyisocyanate (EXCELHARDENER X-19, manufactured by Asia Industries Co., Ltd., the same shall apply hereinafter), 41.8 parts of polyoxypropylene glycol (Sannix PP-1000, manufactured by Sanyo Kasei Co., Ltd., molecular weight = 1000, the same applies hereinafter), and 3 xylene. 18.1 parts were charged and the temperature was raised to 80°C. Further, 0.1 part of dibutyltin dilaurate was added and reacted at the same temperature for 10 hours to obtain a curing agent.
(3) Preparation of Topcoat Composition The main agent and curing agent obtained above were blended at a ratio of main agent/curing agent = 3/2 (mass ratio) and well mixed to obtain a topcoat composition.

[Examples 2 and 3]
A main agent and a curing agent were prepared in the same manner as in Example 1, except that the composition of each component was changed according to Table 1, to obtain a topcoat composition.

[Example 4]
(1) (A1) Preparation of main agent 190.0 parts of acrylic polyol, 20.0 parts of silica particles, 20.0 parts of flux-calcined diatomaceous earth (Radiolite 700, manufactured by Hayashi Kasei Co., Ltd., average particle size _d50 = 23.4 µm), 135.4 parts of titanium oxide particles, 234.6 parts of xylene, and 600 parts of glass beads are charged in a mixing vessel and dispersed for 1 hour in a paint shaker to obtain a main agent. was.
(2) Preparation of (A2) Curing Agent A curing agent was obtained in the same manner as in Example 1.
(3) Preparation of Topcoat Composition The main agent and curing agent obtained above were blended at a ratio of main agent/curing agent = 3/2 (mass ratio) and well mixed to obtain a topcoat composition.

[Examples 5 and 6]
A topcoat composition was obtained in the same manner as in Example 1, except that the composition of each component was changed according to Table 1.

[Example 7]
(1) (A1) Preparation of main agent A main agent was obtained in the same manner as in Example 1.
(2) (A2) Preparation of Curing Agent A reactor equipped with a stirrer, a thermometer, a condenser and a nitrogen gas inlet tube was charged with 21.4 parts of aliphatic dimer-containing polyisocyanate, 40.0 parts of polyoxypropylene glycol, and 311.3 parts of xylene, and heated to 80°C. Further, 0.1 part of dibutyltin dilaurate was added and reacted at the same temperature for 10 hours. After cooling, 27.2 parts of modified H6XDI isocyanurate (Takenate D-127A, manufactured by Mitsui Chemicals, Inc.) was charged and mixed to obtain a curing agent.
(3) Preparation of Topcoat Composition The main agent and curing agent obtained above were blended at a ratio of main agent/curing agent = 3/2 (mass ratio) and well mixed to obtain a topcoat composition.

[Examples 8 to 11]
A topcoat composition was obtained in the same manner as in Example 1, except that the composition of each component was changed according to Table 1.

[Comparative Examples 1 to 5]
A topcoat composition was obtained in the same manner as in Example 1, except that the composition of each component was changed according to Table 2.

[Comparative Example 6]
A topcoat composition was obtained in the same manner as in Example 7, except that the composition of each component was changed according to Table 2.

[Comparative Examples 7 to 11]
A topcoat composition was obtained in the same manner as in Example 1, except that the composition of each component was changed according to Table 2.

The topcoat compositions prepared in the above Examples and Comparative Examples were evaluated as follows. The results are also shown in Table 3.
(1) Specular glossiness Each topcoat composition was applied to one side of a glass plate (200 × 100 × 2 mm) using a film applicator with a gap of 150 µm, and the coated surface was placed horizontally and dried for 48 hours under standard conditions (temperature 23 ° C., relative humidity 50%) to prepare a test specimen. The specular glossiness (measurement angle 60°) of the obtained specimen was measured with a specular glossiness meter specified in JIS K5600-4-7:1999, and evaluated in the following three stages.
○: Specular glossiness less than 5 △: Specular glossiness 5 or more and less than 10 ×: Specular glossiness 10 or more (2) Extensibility Extensibility was measured using a tensile tester (manufactured by Shimadzu Corporation, Autograph AG-5000C), and the elongation rate until breakage was measured at a tensile speed of 200 mm / min, and evaluated in the following three stages.
In addition, the test piece was prepared by spraying the topcoat composition on a polypropylene test plate so that the dry film thickness was 50 μm, drying for 7 days under standard conditions to form a coating film, and then peeling off the coating film from the test plate and punching using a No. 2 dumbbell.
○: Elongation rate of 100% or more △: Elongation rate of 50% or more and less than 100% ×: Elongation rate of less than 50% (3) Accelerated weather resistance The accelerated weather resistance test was performed using a super accelerated weather resistance tester (manufactured by Iwasaki Electric Co., Ltd., Eye Super UV Tester), and the color change (ΔE ^* ) before and after the test was measured and evaluated in the following three stages. The test conditions were a wavelength of 295 to 450 nm, an ultraviolet irradiation intensity of 100 mW/cm ² , a black panel temperature of 63° C., 50% RH, and 125 cycles (1000 hours) of 4 hours of irradiation and 4 hours of dew condensation per cycle.
The test piece was prepared by spray-coating the topcoat composition on a flexible board of 50×50×4 mm so that the dry film thickness was 50 μm, and drying for 7 days under standard conditions.
○: ΔE ^* is less than 2 △: ΔE ^* 2 or more and less than 5 ×: ΔE ^* is 5 or more

As shown in Table 3, the coating film prepared from the topcoat composition of each example is superior to the coating film prepared from the topcoat composition of each comparative example in terms of specular glossiness, extensibility and accelerated weather resistance.

Claims (3)

A two-component urethane coating waterproof topcoat composition comprising (A1) a main agent and (A2) a curing agent,
The (A1) main agent contains (a) an acrylic polyol and (b) SiO ₂ -containing inorganic particles, and 20 to 60 parts by mass of the (b) SiO ₂ -containing inorganic particles per 100 parts by mass (solid content) of the (a) acrylic polyol,
The (b) SiO ₂ -containing inorganic particles contain at least one kind of SiO ₂ -containing inorganic particles having an average particle diameter of 1 to 20 μm , and 20 parts by weight or more of the SiO ₂ -containing inorganic particles having an average particle diameter of 20 μm or less per 100 parts by weight (solid content) of the (a) acrylic polyol,
The (A2) curing agent contains (c) a polyisocyanate, and the polyisocyanate (c) contains 30% by mass or more of at least one dimer selected from the group consisting of (d) an aliphatic isocyanate and an alicyclic isocyanate, and contains at least one urethane prepolymer which is a reaction product of a polyisocyanate containing two or more isocyanate groups per molecule and a polyol having a molecular weight of 400 to 3,000,
The ratio (solid content) of the (d) urethane prepolymer in the (A2) curing agent is 70% by mass or more,
The mass ratio (solid content) of (a) acrylic polyol and (c) polyisocyanate is 80/20 to 30/70, and the reaction molar ratio ([NCO]/[OH]) is 0.5 to 2.0. The two-component urethane coating film waterproofing topcoat paint composition according to claim 1, wherein the (b) SiO ₂ -containing inorganic particles include at least one type of SiO ₂ -containing inorganic particles having an average particle size of 1 to 10 µm , and 20 parts by mass or more of the SiO ₂ -containing inorganic particles having an average particle size of 1 to 10 µm per 100 parts by mass (solid content) of the (a) acrylic polyol. 3. The two-component urethane coating waterproof topcoat coating composition according to claim 1, wherein the mass ratio (solid content) of (a) acrylic polyol and (c) polyisocyanate is 75/25 to 35/65.