JP7073064B2 - Paint composition - Google Patents

Description

The present invention relates to a coating composition.

Conventionally, measures to prevent scratches caused by car wash machines and scratches around keyholes have been desired, but recently, automobile users who place importance on appearance have been demanding improvement for these scratches. Therefore, in order to enhance the commercial power of automobiles, it is an important issue for automobile manufacturers to develop a paint film capable of forming a coating film having excellent "scratch resistance" and "scratch resistance".

However, the automobile coating film must have not only car wash resistance and scratch resistance around the keyhole, but also many coating film performances such as impact resistance, weather resistance, finish property, and adhesiveness. A technology that simply softens or hardens the paint film does not provide a paint film that satisfies all of these, and automobile paint manufacturers have a well-balanced clear paint composition for automobiles that simultaneously satisfies multiple performances. I'm having a hard time developing.

Patent Document 1 describes a hydroxyl group-containing acrylic resin containing a monomer having a long-chain hydroxyalkyl group having 4 or more carbon atoms and a lactone-modified monomer in a specific ratio as a clear coating composition for automobiles having improved scratch resistance. And a clear coating composition containing a polyisocyanate compound are disclosed.
Patent Document 2 discloses a coating material comprising an oligocarbonate polyol, a hydroxy functional polyacrylate polyol, and an OH-reactive (poly) isocyanate cross-linking agent.

Japanese Unexamined Patent Publication No. 2006-176632 Japanese Unexamined Patent Publication No. 2007-16231

However, in the coating composition disclosed in Patent Document 1, as the content of the lactone-modified monomer increases, the scratch resistance improves, but the acid resistance decreases, so that it is difficult to achieve both scratch resistance and acid resistance at the same time. Is. Further, in Patent Document 2, although the chemical resistance (alkali resistance and acid resistance) is improved due to the effect of the oligocarbon carbonate polyol component, the scratch resistance is not sufficient and improvement is desired.

In view of the above problems, the present invention has initial scratch resistance (scratch resistance) further superior to that of conventional paint compositions, scratch recovery after scratch damage, and weather resistance and acid resistance. An object of the present invention is to provide a coating composition having excellent properties.

As a result of diligent studies, the present inventors have found a coating composition that can solve the above problems by combining a hydroxyl group-containing acrylic resin, a polycarbonate polyol having a specific number of hydroxyl groups and a number average molecular weight, and a curing agent. We have found that it can be obtained and have completed the present invention.
That is, the present invention includes the following aspects.

（式中、Ｒ₁は、炭素数２～２０の二価の脂肪族又は脂環族炭化水素を表す。）
［３］
前記（ｂ）ポリカーボネートポリオールにおける式（１）で表される繰り返し単位の内２０モル％以上が、下記式（２）で表される繰り返し単位であり、かつ式（１）で表される繰り返し単位の内２０モル％以上が、下記式（３）で表される繰り返し単位である、［２］に記載の塗料組成物。

［４］
前記（ａ）水酸基含有アクリル樹脂の数平均分子量が５００～１００００であり、前記（ａ）水酸基含有アクリル樹脂の水酸基価が５０～３００ｍｇＫＯＨ／ｇである、［１］～［３］のいずれかに記載の塗料組成物。
［５］
前記（ｂ）ポリカーボネートポリオールの含有量が、前記（ａ）水酸基含有アクリル樹脂１００質量部に対して５～６０質量部である、［１］～［４］のいずれかに記載の塗料組成物。
［６］
前記（ｃ）硬化剤が、１分子中に２．５以上のイソシアネート基及び／又はブロックドイソシアネート基を有する、脂肪族及び／又は脂環族有機イソシアネート化合物である、［１］～［５］のいずれかに記載の塗料組成物。
［７］
前記（ａ）水酸基含有アクリル樹脂由来の水酸基と前記（ｂ）ポリカーボネートポリオール由来の水酸基との合計モル数と、前記（ｃ）硬化剤に含まれるイソシアネート基モル数と、の当量比（ＯＨ基モル数／ＮＣＯ基モル数）が、１／０．５～１／２．０である、［６］に記載の塗料組成物。
［８］
さらに不活性有機溶剤を組成物全量に対し１～９０質量％含む、［１］～［７］のいずれかに記載の塗料組成物。 [1]
It contains (a) a hydroxyl group-containing acrylic resin, (b) a polycarbonate polyol, and (c) a curing agent.
The average hydroxyl valence in one molecule of the (b) polycarbonate polyol is 2.2 to 3.5, and the average hydroxyl value is 2.2 to 3.5.
(B) A coating composition having a number average molecular weight of (b) a polycarbonate polyol of 500 to 5000.
[2]
The polycarbonate polyol (b) described above
A polycarbonate polyol having a repeating unit represented by the following formula (1) and a terminal hydroxyl group, and / or
The coating composition according to [1], which is a polycarbonate polyol having a repeating unit represented by the following formula (1), a terminal hydroxyl group, and a urethane bond.

(In the formula, R ₁ represents a divalent aliphatic or alicyclic hydrocarbon having 2 to 20 carbon atoms.)
[3]
In the polycarbonate polyol (b), 20 mol% or more of the repeating units represented by the formula (1) are the repeating units represented by the following formula (2), and the repeating unit represented by the formula (1). The coating composition according to [2], wherein 20 mol% or more of the above is a repeating unit represented by the following formula (3).

[4]
Any of [1] to [3], wherein the (a) hydroxyl group-containing acrylic resin has a number average molecular weight of 500 to 10,000, and the (a) hydroxyl group-containing acrylic resin has a hydroxyl value of 50 to 300 mgKOH / g. The described paint composition.
[5]
The coating composition according to any one of [1] to [4], wherein the content of the (b) polycarbonate polyol is 5 to 60 parts by mass with respect to 100 parts by mass of the (a) hydroxyl group-containing acrylic resin.
[6]
[1] to [5], wherein the (c) curing agent is an aliphatic and / or alicyclic organic isocyanate compound having 2.5 or more isocyanate groups and / or blocked isocyanate groups in one molecule. The coating composition according to any one of.
[7]
Equivalent ratio (OH group molars) of the total number of moles of the hydroxyl group derived from the (a) hydroxyl group-containing acrylic resin and the hydroxyl group derived from the (b) polycarbonate polyol and the number of moles of the isocyanate group contained in the (c) curing agent. The coating composition according to [6], wherein (number / number of moles of NCO groups) is 1 / 0.5 to 1 / 2.0.
[8]
The coating composition according to any one of [1] to [7], further containing 1 to 90% by mass of an inert organic solvent with respect to the total amount of the composition.

According to the coating composition of the present invention, it has an initial scratch resistance (scratch resistance) further superior to that of a conventional paint composition, a scratch recovery property after being damaged by scratches, and a weather resistance. It is possible to provide a coating composition having excellent acid resistance.

Hereinafter, embodiments for carrying out the present invention (hereinafter, abbreviated as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

≪Paint composition≫
The coating composition of the present embodiment contains (a) a hydroxyl group-containing acrylic resin, (b) a polycarbonate polyol and (c) a curing agent, and (b) has an average hydroxyl value of 2.2 in one molecule of the polycarbonate polyol. It is about 3.5, and (b) the number average molecular weight of the polycarbonate polyol is 500 to 5000.

<(A) Hydroxyl group-containing acrylic resin>
The (a) hydroxyl group-containing acrylic resin used in the present embodiment is used as a main component of a coating composition and is a component that imparts surface hardness, water resistance, weather resistance, heat resistance, and the like. The (a) hydroxyl group-containing acrylic resin of the present embodiment is not particularly limited as long as it is a polymer that requires a structural unit derived from an acrylic monomer having a hydroxyl group, and is appropriately an acrylic single amount having a carboxyl group. It is a copolymer further containing structural units derived from the body, other acrylic monomers, acrylic monomers having a copolymerizable ester group, and other monomers such as vinyl monomers. The type of structural unit constituting the polymer is not particularly limited.

Examples of the acrylic monomer having a hydroxyl group include (meth) acrylic acid 1-hydroxymethyl, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 3-hydroxypropyl, and (meth) acrylic acid 4-. Examples thereof include hydroxybutyl, 2-hydroxyethyl (meth) acrylate, and ε-caprolactone adducts thereof. These may be used alone or in combination of two or more as required.

Examples of the acrylic monomer having a carboxyl group include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and their anhydrides. These may be used alone or in combination of two or more as required.

Examples of the acrylic monomer having an ester group include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, and n-. Amil (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) Acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) ) Acrylate and the like can be mentioned. These may be used alone or in combination of two or more as required.

Examples of other vinyl-based monomers include acrylamide-based monomers such as acrylamide, methacrylamide, N-methylolacrylamide, N, N-dimethylacrylamide, and diacetoneacrylamide; styrene and the like. These may be used alone or in combination of two or more as required.
The hydroxyl group-containing acrylic resin can be obtained by appropriately selecting a monomer from the above acrylic monomers and vinyl monomers and polymerizing them with a radical polymerization initiator, a chain transfer agent, or the like.

The hydroxyl value of the (a) hydroxyl group-containing acrylic resin is not particularly limited, but is preferably 50 to 300 mgKOH / g, and more preferably 70 to 200 mgKOH / g. When the hydroxyl value is 50 or more, the coating film hardness and the coating film strength of the coating film obtained from the coating composition tend to be further improved, and the initial scratch resistance tends to be better. Further, when the hydroxyl value is 300 or less, the crosslink density of the coating film obtained from the coating composition is adjusted to an appropriate range, and the scratch recovery tends to be better.

The number average molecular weight of the (a) hydroxyl group-containing acrylic resin is not particularly limited, but is preferably 500 to 10000, more preferably 1500 to 8000, and even more preferably 2000 to 6000. (A) When the number average molecular weight of the hydroxyl group-containing acrylic resin is 500 or more, the scratch recovery of the coating film obtained from the coating composition tends to be better. Further, (a) when the number average molecular weight of the hydroxyl group-containing acrylic resin is 10,000 or less, the viscosity of the coating composition is adjusted to an appropriate range, the coating appearance is improved, and the initial scratch resistance tends to be improved. It is in.

The glass transition temperature of the (a) hydroxyl group-containing acrylic resin is not particularly limited, but is preferably −20 to 60 ° C., more preferably 0 ° C. to 40 ° C. (A) When the glass transition temperature of the hydroxyl group-containing acrylic resin is −20 ° C. or higher, the surface hardness of the coating film obtained from the coating composition tends to be high, and the initial scratch resistance tends to be good. Further, (a) when the glass transition temperature of the hydroxyl group-containing acrylic resin is 60 ° C. or lower, the hardness of the coating film obtained from the coating composition is adjusted to an appropriate range, and the scratch recovery tends to be better. ..

(A) As the hydroxyl group-containing acrylic resin, for example, a commercially available product can be used, specifically, Setalux 1152, Setalux 1184, Setalux 1767 manufactured by Nuplex, LR-7606 manufactured by Mitsubishi Rayon, and Super Rack O manufactured by Nippon Paint Co., Ltd. -150 clear or the like can be preferably used.

<(B) Polycarbonate polyol>
The (b) polycarbonate polyol used in the coating composition of the present embodiment is a polycarbonate polyol having an average hydroxyl value of 2.2 to 3.5 and a number average molecular weight of 500 to 5000 in one molecule. (B) The polycarbonate polyol is preferably a polycarbonate polyol having a repeating unit represented by the following formula (1) and a terminal hydroxyl group.

(In the formula, R ₁ represents a divalent aliphatic or alicyclic hydrocarbon having 2 to 20 carbon atoms.)
The proportion of the polycarbonate polyol having the repeating unit represented by the formula (1) and the terminal hydroxyl group in the total (b) polycarbonate polyol is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably. Is 80% by mass or more.

The polycarbonate polyol (b) is not particularly limited, but for example, (d) a bifunctional diol compound, (e) a trihydric or higher functional alcohol, and (f) a carbonic acid ester are used as raw materials, and Polymer Reviews 9th. It can be synthesized by a transesterification reaction as described in Volume, pages 9-20.

The (d) bifunctional diol compound used in the present embodiment is not particularly limited, and is, for example, ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1 , 5-Pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2-methyl-1,8-octane Diol, neopentyl glycol, 2-isopropyl-1,4-butanediol, 2-ethyl-1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5-pentane Di here, 2,4-diethyl-1,5-pentanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2-bis (4-hydroxycyclohexyl) -propane, etc. Examples thereof include diols having a divalent aliphatic or alicyclic hydrocarbon skeleton having 2 to 20 carbon atoms.
These (d) bifunctional diol compounds may be used alone or in combination of two or more. Of these, it is preferable to use a linear alkylene diol having 2 to 10 carbon atoms.

The polycarbonate polyol (b) is preferably a polycarbonate polyol having a repeating unit represented by the following formula (1) and a terminal hydroxyl group. Further, among the repeating units represented by the formula (1), preferably 20 mol% or more, more preferably 30 mol% or more are the repeating units represented by the following formula (2), and the formula (1) is used. Of the repeating units represented, preferably 20 mol% or more, more preferably 30 mol% or more are the repeating units represented by the following formula (3). When the repeating unit represented by the formula (2) and the formula (3) is 20 mol% or more, the scratch recovery of the coating film obtained from the coating composition tends to be good.
The upper limit of the repeating unit represented by the formula (2) and the formula (3) is not particularly limited, but is 80 mol% or less, respectively.

(In the formula, R ₁ represents a divalent aliphatic or alicyclic hydrocarbon having 2 to 20 carbon atoms.)

The number average molecular weight of the (b) polycarbonate polyol used in the present embodiment is 500 to 5000, preferably 900 to 3000, and more preferably 1000 to 2000. (B) When the number average molecular weight of the polycarbonate polyol is 500 or more, the scratch recovery of the coating film tends to be good. Further, when the number average molecular weight is 5000 or less, the reaction with isocyanate at the time of curing is accelerated, the drying time can be shortened, and the initial scratch resistance of the obtained coating composition tends to be good.

The method for controlling the number average molecular weight of the (b) polycarbonate polyol within the above range is not particularly limited, and examples thereof include (b) a method for controlling the amount of the diol monomer distilled off during the polymerization of the polycarbonate polyol.

In the present embodiment, (b) a polyhydric alcohol compound having a trifunctionality or higher is used in addition to (d) a bifunctional diol as a raw material for the polycarbonate polyol. (E) The polyhydric alcohol compound is not particularly limited, and examples thereof include trimethylolethane, trimethylolpropane, hexanetriol, pentaerythritol, and glycerin.

Further, in the present embodiment, as the raw material of (b) the polycarbonate polyol, (d) a polyamine compound having a polyoxyalkylene chain can be used in addition to (d) a bifunctional diol. (H) The polyamine compound having a polyoxyalkylene chain is not particularly limited, and examples thereof include a polyamine compound having a polyoxyalkylene chain represented by the following formula (4).

(In the formula, R represents a divalent aliphatic hydrocarbon having 2 to 4 carbon atoms, and n is an integer of 5 or more and 80 or less, preferably an integer of 10 or more and 50 or less.)

As the compound represented by the above formula (4), a commercially available product can be used, and specifically, San-Amir TAP-10 (number average molecular weight 674, manufactured by Sanyo Chemical Industries, Ltd.), San-Amir TAP-40 ( Number average molecular weight 2250, manufactured by Sanyo Chemical Industries, Ltd.) and the like.

The average hydroxyl valence in one molecule of the polycarbonate polyol (b) of the present embodiment is 2.2 to 3.5, preferably 2.3 to 2.9, and more preferably 2.4 to 2.7. If the average hydroxyl value in one molecule of the polycarbonate polyol is less than 2.2, the initial scratch resistance, scratch recovery, and acid resistance are inferior, which is not preferable. If the average hydroxyl valence in one molecule of the polycarbonate polyol exceeds 3.5, the scratch recovery is deteriorated, which is not preferable. The average hydroxyl valence in one molecule of the polycarbonate polyol is the charge of the bifunctional diol, the trifunctional or higher functional alcohol, and / or the polyamine compound having the (h) polyoxyalkylene chain at the time of synthesizing the polycarbonate polyol. It can be adjusted by the ratio.
Specifically, the average hydroxyl value number in this embodiment can be measured by the method described in Examples.

(H) When a polyamine compound having a polyoxyalkylene chain is used, the amino group in the polyamine compound having a polyoxyalkylene chain is a carbonyl group in the polycarbonate polyol molecule as shown in the following formula (5). Makes a nuclear attack and forms a urethane bond.
Further, the polyamine compound having the polyoxyalkylene chain of the above formula (4) also has a hydroxyl group at the end of the oxyalkylene chain, and this hydroxyl group also causes a transesterification reaction during the synthesis of the polycarbonate polyol. Therefore, the polyamine compound having the polyoxyalkylene chain of the above formula (4) can also be used as a trifunctional compound.

Therefore, a part of the carbonate structure in the polycarbonate polyol molecule may be replaced with a urethane bond. One aspect of (b) a polycarbonate polyol in the present embodiment is a polycarbonate polyol containing a urethane bond, and specifically, has a repeating unit represented by the formula (1), a terminal hydroxyl group, and a urethane bond. It is a polycarbonate polyol.

Examples of the (f) carbonic acid ester used in the synthesis of (b) polycarbonate polyol in the present embodiment include dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate and dibutyl carbonate; diaryl carbonate such as diphenyl carbonate; ethylene. Examples thereof include carbonates, trimethylene carbonates, 1,2-propylene carbonates, 1,2-butylene carbonates, 1,3-butylene carbonates, alkylene carbonates such as 1,2-pentylene carbonates; and the like. From the viewpoint of easy availability and easy setting of conditions for the polymerization reaction, it is preferable to use dimethyl carbonate, diethyl carbonate, diphenyl carbonate, or ethylene carbonate.

A catalyst may or may not be added to the production of the polycarbonate polyol. When adding a catalyst, it can be freely selected from ordinary transesterification reaction catalysts. Examples of the catalyst include metals such as lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, aluminum, titanium, cobalt, germanium, tin, lead, antimony, arsenic, and cerium. Salts containing these metals, alkoxides, organic compounds and the like are used. Among the above catalysts, compounds containing titanium, tin and lead are preferable. The amount of the catalyst used is usually (d) a bifunctional diol compound, (e) a trihydric or higher polyhydric alcohol and / or (h) a polyamine compound having a polyoxyalkylene chain, and (f) a carbonic acid ester. It is 0.00001 to 0.1% of the total mass of.

As described above, (b) a method for producing a polycarbonate polyol uses (d) a bifunctional diol compound, (e) a trifunctional or higher polyhydric alcohol, and (f) a carbonic acid ester as raw materials for a transesterification reaction. Can be synthesized. More specifically, a predetermined ratio of one or more (d) bifunctional diol compounds, a predetermined ratio of one or more (e) trifunctional or higher polyvalent alcohols, and predetermined amounts. One or more of the (f) carbonic acid esters in the above ratios are mixed, and the transesterification reaction is carried out at a temperature of 100 to 200 ° C. under normal pressure or reduced pressure, in the absence or presence of a transesterification catalyst. The produced (f) carbonic acid ester-derived alcohol is distilled off to obtain a polycarbonate polyol having a molecular weight of about 300 to 500. Then, the unreacted (f) carbonic acid ester, (d) bifunctional diol and (e) trifunctional or higher polyhydric alcohol were distilled off at 130 to 230 ° C. under reduced pressure, and the desired molecular weight (of the desired molecular weight) was subjected to the condensation reaction. b) Polycarbonate polyol can be obtained. (B) The composition of the polycarbonate polyol and the average number of hydroxyl valences in one molecule can be controlled by the initial charge ratio of each component and the amount of each raw material and reaction product distilled during production.

Further, as a method for producing the (b) polycarbonate polyol of the present embodiment, one or more (d) bifunctional diol compounds having a predetermined ratio and one or more (f) having a predetermined ratio have been prepared in advance. ) The carbonate ester is mixed, and the ester exchange reaction is carried out at a temperature of 100 to 200 ° C. under normal pressure or reduced pressure, in the absence or presence of the ester exchange catalyst, and (f) the alcohol derived from the carbonate ester is retained. After the above, a polycarbonate diol having a molecular weight of about 300 to 500 was obtained, and then the unreacted (f) carbonic acid ester and (d) bifunctional diol were distilled off at 130 to 230 ° C. under reduced pressure, and a predetermined condensation reaction was carried out. To obtain a polycarbonate diol having a molecular weight, add one or more (e) trifunctional or higher polyhydric alcohols and / or (h) a polyamine compound having a polyoxyalkylene chain in a predetermined ratio, and add 130 to 230 ° C. The desired (b) polycarbonate polyol can also be obtained by carrying out an ester exchange reaction and / or a nucleophilic substitution reaction (depolymerization) of an amine at the temperature of.

<(C) Curing agent>
As the curing agent (c) used in the present embodiment, (g) an organic polyisocyanate compound is preferably used. (G) The organic polyisocyanate compound is preferably polyisocyanate derived from an aliphatic and / or alicyclic organic diisocyanate compound, particularly from the viewpoint of weather resistance, and specifically, for example, hexamethylene. Examples thereof include polyisocyanates derived from aliphatic or aliphatic diisocyanates such as diisocyanate (HDI) and isophorone diisocyanate (IPDI). Furthermore, these polyisocyanates are blocked with known blocking agents such as lower alcohols such as butanol and 2-ethylhexanol, methylethylketone oxime, lactams, phenols, imidazoles and active methylene compounds, so-called blocked isocyanates. A system curing agent can also be used. The polyisocyanate compound is not particularly limited, and is, for example, Sumijuru 44S, 44V70 (all manufactured by Sumika Bayer Urethane), Dismodule HL (manufactured by Sumika Bayer Urethane) which is a copolymer of TDI and HDI, and Asahi Kasei Co., Ltd. Various urethanes manufactured by the company, namely, Duranate 24A-100, Duranate 22A-75PX, Duranate 18H-70B, Duranate 21S-75E, Duranate THA-100, Duranate TPA-100, Duranate MFA-75X, Duranate TSA-100, Duranate TSS- 100, Duranate TSE-100, Duranate D-101, Duranate D-201, Duranate P-301-75E, Duranate E-402-90T, Duranate E-402-90T, Duranate E-405-80T, Duranate ME20-100, Available as Duranate 17B-60PX, Duranate TPA-B80X, Duranate MF-B60X, Duranate E-402-B80T, Duranate ME20-B80S, Duranate WB40-100, Duranate WB40-80D, Duranate WT20-100, Duranate WT30-100, etc. Is. From the viewpoint of improving acid resistance, alkali resistance, alcohol resistance, oil resistance, abrasion resistance, and scratch resistance of the cured coating film, the organic polyisocyanate compound contains 2.5 or more isocyanate groups in one molecule and / Alternatively, it is preferably an aliphatic and / or alicyclic organic isocyanate compound having a blocked isocyanate group, specifically, a diisocyanate derivative such as biuret, allophanate, uretdione, isocyanurate, and a polyhydric alcohol adduct type. preferable.

The blending ratio of the (a) hydroxyl group-containing acrylic resin and (b) polycarbonate polyol is preferably 5 to 60 parts by mass, more preferably 5 to 60 parts by mass, as the blending amount of (b) polycarbonate polyol with respect to 100 parts by mass of (a) hydroxyl group-containing acrylic resin. Is 8 to 40 parts by mass, more preferably 10 to 30 parts by mass. (A) When the blending amount of the polycarbonate polyol (b) is 5 parts by mass or more with respect to 100 parts by mass of the hydroxyl group-containing acrylic resin, the scratch recovery of the coating film obtained from the coating composition is excellent. Further, by setting the blending amount of (b) the polycarbonate polyol to 60 parts by mass or less with respect to 100 parts by mass of the (a) hydroxyl group-containing acrylic resin, the initial scratch resistance of the coating film obtained from the coating composition becomes good.

The compounding ratio of (a) the hydroxyl group-containing acrylic resin, (b) the polycarbonate polyol, and (c) the curing agent is the hydroxyl group derived from (a) the hydroxyl group-containing acrylic resin from the viewpoint of the drying property of the coating film and the coating film performance. (B) The total number of moles of hydroxyl groups derived from the polycarbonate polyol (hereinafter, also abbreviated as "OH group moles") and the number of moles of isocyanate groups contained in the curing agent (hereinafter, also abbreviated as "NCO group moles"). The equivalent ratio (number of moles of OH groups / number of moles of NCO groups) is preferably 1 / 0.5 to 1 / 2.0 (equivalent ratio), and 1 / 0.7 to 1 / 1.3 (equivalent). Ratio) is more preferable, and 1 / 0.8 to 1 / 1.2 (equivalent ratio) is further preferable. When the number of moles of OH groups is 1 equivalent, the physical characteristics of the coating film tend to be better when the number of moles of NCO groups is 0.5 equivalent or more. When the number of moles of NCO groups is 2.0 equivalents or less when the number of moles of OH groups is 1 equivalent, the curing rate can be made faster, and the flexibility of the obtained coating film tends to be more excellent.

<Inactive organic solvent>
The coating composition of the present embodiment may contain 1 to 90% by mass of an inert organic solvent with respect to the total amount of the coating composition, if necessary, in order to adjust the workability at the time of coating. The content of the inert organic solvent is more preferably 10 to 70% by mass, further preferably 20 to 50% by mass.

The inert organic solvent to be used is not particularly limited, but is preferably an organic solvent that is substantially inert to the polyisocyanate compound and does not have active hydrogen. Examples thereof are not particularly limited, but are, for example, hydrocarbons such as pentane, hexane, heptane, octane, decane, petroleum ether, petroleum benzine, ligroin, petroleum spirit, cyclohexane, and methylcyclohexane, trichlorofluoroethane, and tetrachlorodifluoroethane. , Perfluoroether and other fluorinated petroleum-based inert liquids, perfluorocyclohexane, perfluorobutyltetratetra, perfluorodecalin, perfluoro-n-butylamine, perfluoropolyether, dimethylpolysiloxane and the like alone or in admixture. Can be mentioned. Further, a single solvent such as methyl ethyl ketone, acetone, ethyl acetate, butyl acetate, toluene, xylene and the like can be mentioned.

<Other additives>
The coating composition of the present embodiment contains a curing accelerator (catalyst), a filler, a flame retardant, a dye, an organic or inorganic pigment, a mold release agent, a fluidity adjusting agent, a plasticizer, and an antioxidant depending on various uses. , Ultraviolet absorber, light stabilizer, defoamer, leveling agent, colorant, solvent and the like can be added.

The curing accelerator is not particularly limited, and is, for example, monoamine triethylamine, N, N-dimethylcyclohexylamine, diamine tetramethylethylenediamine, other triamines, cyclic amines, alcohol amines such as dimethylethanolamine, and etheramines. The metal catalyst is not particularly limited, but for example, potassium acetate, potassium 2-ethylhexanoate, calcium acetate, lead octylate, dibutyltin dilaurate, tin octylate, bismuth neodecanoate, bismuth oxycarbonate, bismuth 2 -Generally used substances such as ethyl hexanoate, zinc octylate, zinc neodecanoate, phosphine, and phosphorin can be used.

The filler and pigment are not particularly limited, but for example, woven fabric, glass fiber, carbon fiber, polyamide fiber, mica, kaolin, bentonite, metal powder, azo pigment, carbon black, clay, silica, talc, gypsum, alumina. Commonly used materials such as white and barium carbonate can be used.

The release agent, fluidity adjuster, and leveling agent are not particularly limited, and for example, silicone, aerosil, wax, stearate, polysiloxane such as BYK-331 (manufactured by BYK Chemical Co., Ltd.) and the like are used.

As the additive used in this embodiment, it is preferable that at least an antioxidant, a light stabilizer and a heat stabilizer are used. These antioxidants are not particularly limited, and are, for example, aliphatic, aromatic or alkyl group substituted aromatic esters of phosphoric acid, phosphite, hypophosphite derivatives, phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, and the like. Phosphorus compounds such as polyphosphonate, dialkylpentaerythritol diphosphite, dialkylbisphenol A diphosphite; phenolic derivatives, especially hindered phenol compounds, thioethers, dithioates, mercaptobenzimidazoles, thiocarbanilides, thiodipropionic acid esters, etc. Sulfur-containing compounds; tin-based compounds such as summalate and dibutyltin monooxide can be used.
These may be used alone or in combination of two or more.

<Painting method>
The coating method of the coating composition of the present embodiment is not particularly limited, but for example, a method of mixing each component immediately before coating and then applying the coating composition to the substrate by spraying, rolling, brushing or the like is used. It is also possible to mix components other than the curing agent (c) in advance, add the component (c) immediately before application, mix them uniformly, and then apply the mixture.

<Use>
Since the coating composition of the present embodiment is excellent in scratch resistance and scratch recovery, it is suitably used as a clear paint for automobile exteriors and a paint for automobile interiors. Further, it can be preferably used for home electric appliances, OA products, surface treatment of leather, surface treatment of synthetic leather, and the like.

Hereinafter, the present embodiment will be described in more detail with reference to Examples and the like, but the present embodiment is not limited to these examples. The test method and the evaluation of the physical characteristics of the coating film in the following Examples and Comparative Examples were carried out according to the following test methods.

<Test method>
1) Hydroxyl value of polycarbonate polyol (average number of hydroxyl values)
It was measured according to JIS K1557-1.

2) Pendrum hardness The paint solutions prepared in Examples and Comparative Examples were uniformly applied onto a glass plate so that the thickness of the coating film after drying was 30 μm. After drying at room temperature for 15 minutes, it was then dried in an oven at 140 ° C. for 20 minutes and then removed from the oven. After leaving it in a constant temperature room at 23 ° C. for 24 hours, it was subjected to evaluation of pendrum hardness.
The pendrum hardness was measured with a pendrum type hardness tester (using a König pendulum) manufactured by BYK-Gardner.

3) Scratch resistance A coating film was formed on the glass in the same manner as the method used for measuring the hardness of the pen drum. On this coated surface, a 4-row brass brush manufactured by Industry Kowa Co., Ltd. was scratched in parallel with the handle by reciprocating 20 times with a load of 500 g, a stroke speed of 30 cm / sec, and a stroke width of 5 cm. Immediately after the scratch was made, the scratched portion was measured for gloss (gloss): G1 at a 60-degree angle with a variable angle gloss meter manufactured by Suga Test Instruments Co., Ltd. The initial gloss (gloss) of the same portion before the scratch test was set to G0, and the scratch resistance was evaluated by the decrease in gloss according to the following formula (9).
Gloss retention rate (%) = (G1 / G0) x 100 (9)
It is evaluated that the higher the gloss retention rate, the better the scratch resistance.

4) Scratch recovery rate The sample tested in the scratch resistance evaluation in 3) above was left in a constant temperature room at 23 ° C for 24 hours, and then the gloss of the scratched part measured in 3) was measured. It was set to G2. The wound recovery rate was calculated by the following formula (10).
Wound recovery rate (%) = [(G2-G1) / G0] x 100 (10)

5) Acid resistance A coating film was formed on the glass in the same manner as the method used for measuring the hardness of the pen drum. The appearance of this coating film was observed to change by the drip method according to JIS K5600-6-1. As the acid, 0.1N sulfuric acid was used, and the appearance after 12 hours was observed. The case where there was no change in appearance was evaluated as ◯, the case where there was a slight liquid mark was evaluated as Δ, and the case where the liquid mark was clearly observed was evaluated as ×.

6) Weather resistance A coating film was formed on the glass in the same manner as the method used for measuring the hardness of the pen drum. After exposing this coating film to 1000 hours using a xenon weather meter according to JIS K5600-7-7, the state of the coating film was visually determined.
◯: No water stain marks △: Slight water stain marks observed ×: Significant water stain marks observed

[Polycarbonate polyol polymerization example 1]
236 g (2 mol) of 1,6-hexanediol (1,6-HDO), 1,5-pentanediol (1,5) in a 2 L glass flask equipped with a rectification column filled with a regular filling and a stirrer. -PDO) 208 g (2 mol), trimethylolpropane (TMP) 17.4 g (0.13 mol) and ethylene carbonate 352 g (4 mol) were charged, and after stirring and dissolving at 70 ° C., 0.05 g of titanium tetrabutoxide was added as a catalyst. rice field. The mixture was heated in an oil bath set at 175 ° C., and reacted for 12 hours at an internal temperature of 150 ° C. in a flask and a vacuum degree of 1.0 to 1.5 kPa while removing a part of the distillate from the reflux head at a reflux ratio of 4. After that, the rectification column was replaced with a simple distillation apparatus, heated in an oil bath set at 165 ° C, the internal temperature of the flask was reduced to 150 to 160 ° C, and the degree of vacuum was reduced to 0.5 kPa, and the diol and ethylene remaining in the flask were reduced. The carbonate and was removed. Then, the setting of the oil bath was raised to 175 ° C., and the reaction was carried out at an internal temperature of 160 to 170 ° C. of the flask for another 2 hours while removing the diol produced. This reaction gave a viscous liquid at room temperature. The obtained polycarbonate polyol has a number average molecular weight of 1030 (polystyrene equivalent) by GPC analysis, a composition (mol%) of 1,6-HDL: 1,5-PDL: TMP = 48.0: 46.5: 5.5, The hydroxyl value was 132.3 mgKOH / g, and the average number of hydroxyl values in one molecule was 2.54. This polycarbonate polyol is referred to as PC-1.

[Polycarbonate polyol polymerization example 2]
236 g (2 mol) of 1,6-hexanediol (1,6-HDO), 1,5-pentanediol (1,5) in a 2 L glass flask equipped with a rectification column filled with a regular filling and a stirrer. -PDO) 208 g (2 mol), trimethylolpropane (TMP) 10.0 g (0.057 mol) and ethylene carbonate 352 g (4 mol) were charged, and after stirring and dissolving at 70 ° C., titanium tetrabutoxide 0.05 g was added as a catalyst. rice field. The mixture was heated in an oil bath set at 175 ° C., and reacted for 12 hours at an internal temperature of 150 ° C. in a flask and a vacuum degree of 1.0 to 1.5 kPa while removing a part of the distillate from the reflux head at a reflux ratio of 4. After that, the rectification column was replaced with a simple distillation apparatus, heated in an oil bath set at 165 ° C, the internal temperature of the flask was reduced to 150 to 160 ° C, and the degree of vacuum was reduced to 0.5 kPa, and the diol and ethylene remaining in the flask were reduced. The carbonate and was removed. Then, the setting of the oil bath was raised to 175 ° C., and the reaction was carried out at an internal temperature of 160 to 170 ° C. of the flask for another 4 hours while removing the diol produced. This reaction gave a viscous liquid at room temperature. The obtained polycarbonate polyol has a number average molecular weight of 2050 (polystyrene equivalent) obtained by GPC analysis, a composition (mol%) of 1,6-HDL: 1,5-PDL: TMP = 49.5: 48.4: 2.1, The hydroxyl value was 66.7 mgKOH / g, and the average number of hydroxyl values in one molecule was 2.43. This polycarbonate polyol is referred to as PC-2.

[Polycarbonate polyol polymerization example 3]
236 g (2 mol) of 1,6-hexanediol (1,6-HDO), 1,5-pentanediol (1,5) in a 2 L glass flask equipped with a rectification column filled with a regular filling and a stirrer. -PDO) 208 g (2 mol) and ethylene carbonate 352 g (4 mol) were charged, and after stirring and dissolving at 70 ° C., 0.05 g of titanium tetrabutoxide was added as a catalyst. The mixture was heated in an oil bath set at 175 ° C., and reacted for 12 hours at an internal temperature of 150 ° C. in a flask and a vacuum degree of 1.0 to 1.5 kPa while removing a part of the distillate from the reflux head at a reflux ratio of 4. After that, the rectification column was replaced with a simple distillation apparatus, heated in an oil bath set at 165 ° C, the internal temperature of the flask was reduced to 150 to 160 ° C, and the degree of vacuum was reduced to 0.5 kPa, and the diol and ethylene remaining in the flask were reduced. The carbonate and was removed. Then, the setting of the oil bath was raised to 175 ° C., and the reaction was carried out at an internal temperature of 160 to 170 ° C. of the flask for another 2 hours while removing the diol produced. This reaction gave a viscous liquid at room temperature. The composition (mol%) of the obtained polycarbonate diol is 1,6-HDL: 1,5-PDL = 52.5: 47.5, the hydroxyl value is 112.2 mgKOH / g, and the average hydroxyl value in one molecule is It was 2.0.
200 g of this polycarbonate diol was placed in a 0.5 L glass flask equipped with a stirrer. Further, 89.4 g of Sun Amir TAP-10 (polyamine compound having a polyoxyalkylene chain, number average molecular weight 674, manufactured by Sanyo Chemical Industries, Ltd.) was added and heated in an oil bath set at 160 ° C., and the internal temperature of the flask was 145. The reaction was carried out at ~ 150 ° C. under stirring for 7 hours. This reaction gave a viscous liquid at room temperature. The obtained polycarbonate polyol had a number average molecular weight of 874 (in terms of polystyrene) by GPC analysis, a hydroxyl value of 162.2 mgKOH / g, and an average hydroxyl value in one molecule of 2.53. This polycarbonate polyol is referred to as PC-3.

[Example 1]
As a hydroxyl group-containing acrylic resin, Nuplex 1152 (xylene / methoxypropyl acetate mixed solution, solid content 61% by mass, solid content equivalent hydroxyl value 139 mgKOH / g, number average molecular weight of hydroxyl group-containing acrylic resin 3000) was 295 g, polycarbonate polyol PC. Add -1 to 20 g, leveling agent BYK-331 (manufactured by BYK Chemical Co., Ltd.) 2.06 g, dibutyltin dilaurate (manufactured by Air Product) 1.2 g, and a mixed solvent of xylene / butyl acetate (70/30) as a thinner. Then, the paint main agent having a solid content of 50% by mass was obtained (the ratio of the polycarbonate polyol in the main agent excluding the solvent was 10%). To this, Duranate TKA-100 (manufactured by Asahi Kasei Co., Ltd .: hexamethylene diisocyanate-based isocyanurate-type curing agent, NCO content = 21.8 wt%, isocyanate group in one molecule: 3) was added to the NCO / OH molar ratio =. A coating composition was prepared by adding and mixing so as to be 1.0 / 1.0. The pendrum hardness, scratch resistance, and scratch recovery were evaluated by the above method, and the results are shown in Table 1.

[Example 2]
A coating composition was prepared in the same manner as in Example 1 except that the polycarbonate polyol PC-2 was used instead of the polycarbonate polyol PC-1 of Example 1. The coating film performance was evaluated and the results are shown in Table 1.

[Examples 3 and 4]
A coating composition was obtained in the same manner as in Examples 1 and 2 except that the amount of Setalux 1152 added in Example 1 was 230 g and the amount of polycarbonate polyol added was 60 g.
The coating film performance was evaluated and the results are shown in Table 1.

[Example 5]
Instead of Setalux 1152, Setalux 1184 (xylene / methoxypropyl acetate mixed solution, solid content 52% by mass, solid content equivalent hydroxyl value 66 mgKOH / g, number average molecular weight of hydroxyl group-containing acrylic resin 3000) was used, and the amount of Setalux 1184 added was 346 g. A coating composition was prepared in the same manner as in Example 1 except for the above.
The coating film performance was evaluated and the results are shown in Table 1.

[Example 6]
A coating composition was prepared in the same manner as in Example 1 except that the polycarbonate polyol PC-3 was used instead of the polycarbonate polyol PC-1 of Example 1. The coating film performance was evaluated and the results are shown in Table 1.

[Example 7]
A coating composition was obtained in the same manner as in Example 6 except that the amount of Setalux 1152 added in Example 6 was 230 g and the amount of the polycarbonate polyol PC-3 added was 60 g. The coating film performance was evaluated and the results are shown in Table 1.

[Comparative Example 1]
A coating composition was obtained in the same manner as in Example 1 except that the polycarbonate polyol PC-1 was blended in Example 1. The coating film performance was evaluated and the results are shown in Table 1.

[Comparative Examples 2 and 3]
Instead of the polycarbonate polyol PC-1 of Example 1, a polycarbonate diol T5651 (number average molecular weight 1000, average hydroxyl value in one molecule 2.0), T5652 (number average molecular weight 2000, average in one molecule) manufactured by Asahi Kasei Co., Ltd. A coating composition was prepared in the same manner as in Example 1 except that the hydroxyl value number 2.0) was used. The coating film performance was evaluated and the results are shown in Table 1.

[Comparative Example 4]
The same as in Example 3 except that the polycarbonate diol T5651 (number average molecular weight 1000, average hydroxyl value 2.0 in one molecule) manufactured by Asahi Kasei Co., Ltd. was used instead of the polycarbonate polyol PC-1 of Example 3. A coating composition was prepared by the method. The coating film performance was evaluated and the results are shown in Table 1.

The paint composition of the present embodiment can be preferably used as a scratch recovery paint for automobile exteriors, interiors, home appliances, OA products, leather surface treatments, synthetic leather surface treatments, and the like.

Claims (6)

It contains (a) a hydroxyl group-containing acrylic resin, (b) a polycarbonate polyol, and (c) a curing agent.
The (b) polycarbonate polyol is a polycarbonate polyol containing (d) a structural unit derived from a bifunctional diol compound and (e) a structural unit derived from a trivalent or higher functional polyvalent component.
The (d) bifunctional diol compound is two or more kinds of linear alkylene diols having 2 to 10 carbon atoms.
The average hydroxyl valence in one molecule of the (b) polycarbonate polyol is 2.2 to 3.5, and the average hydroxyl value is 2.2 to 3.5.
The number average molecular weight of the polycarbonate polyol (b) is 500 to 5000, and the polycarbonate polyol has a number average molecular weight of 500 to 5000.
The polycarbonate polyol (b) described above
A polycarbonate polyol having a repeating unit represented by the following formula (1) and a terminal hydroxyl group, and / or
It is a polycarbonate polyol having a repeating unit represented by the following formula (1), a terminal hydroxyl group, and a urethane bond.
In the polycarbonate polyol (b), 20 mol% or more of the repeating units represented by the formula (1) are the repeating units represented by the following formula (2), and the repeating unit represented by the formula (1). A coating composition in which 20 mol% or more of the above is a repeating unit represented by the following formula (3) .

(In the formula, R ₁ represents a divalent aliphatic or alicyclic hydrocarbon having 2 to 20 carbon atoms.)

The coating composition according to claim 1, wherein the (a) hydroxyl group-containing acrylic resin has a number average molecular weight of 500 to 10000, and the (a) hydroxyl group-containing acrylic resin has a hydroxyl value of 50 to 300 mgKOH / g. The coating composition according to claim 1 or 2 , wherein the content of the polycarbonate polyol (b) is 5 to 60 parts by mass with respect to 100 parts by mass of the (a) hydroxyl group-containing acrylic resin. Any of claims 1 to 3 , wherein the (c) curing agent is an aliphatic and / or alicyclic organic isocyanate compound having 2.5 or more isocyanate groups and / or blocked isocyanate groups in one molecule. The coating composition according to item 1. Equivalent ratio (OH group molars) of the total number of moles of the hydroxyl group derived from the (a) hydroxyl group-containing acrylic resin and the hydroxyl group derived from the (b) polycarbonate polyol and the number of moles of the isocyanate group contained in the (c) curing agent. The coating composition according to claim 4 , wherein the number / number of moles of NCO groups is 1 / 0.5 to 1 / 2.0. The coating composition according to any one of claims 1 to 5 , further comprising an inert organic solvent in an amount of 1 to 90% by mass based on the total amount of the composition.