JP2002167490A - Hardening resin composition composed of acrylic polyol resin and melamine resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hardening type coating material composition, improved in acid resistance even if a melamine-hardening type of a low price, highly balanced in acid resistance and scratch resistance, and also giving a coating film excellent in flex resistance and recoat adhesi. SOLUTION: A hardening resin composition is essentially composed of 0.5-80 pts.wt. of an acrylic polyol composition (A) that is obtained by using a lactone- modified hydroxyalkyl(meth)acrylic ester composition wherein a ratio of a monomer having lactone chains of two or more (n>=2) given by the following formula, is 50% or below, and 0.5-50 pts.wt. of a melamine resin (B), wherein the total of (A) and (B) does not exceed 100 pts.wt. RCH=CR1COO(CR2R3)jOH+ n(lactones)→RCH=CR1COO(CR2R3)jO(CO(CR4R5)x)n-H (wherein R1, R2 and R3 are independently H or CH3, (j) is an integer of 2-6, xn pieces of R4 and R5 are interpedently H or a 1-12C alkyl, (x) is 4-7, (n) is 0 or an integer of 1 or above, and the average value of (n) in the composition is 0.3 or above and below 1.0).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a curable resin composition comprising an acrylic polyol resin containing at least a low lactone-modified hydroxyalkyl (meth) acrylate in a polymerization component and a melamine resin. From the curable resin composition of the present invention, even in the case of a melamine-curable system, a paint having a good balance between scratch resistance and acid resistance can be produced by improving acid resistance.

[0002]

2. Description of the Related Art In recent years, the importance of acrylic paints in the field of coating has increased. The reason is that weather resistance, chemical resistance, contamination resistance, and the like are superior to other alkyd resins, polyester resins, and epoxy resins. For this reason, acrylic coatings are used in various fields such as automobiles, household appliances, metals, and building materials. In coatings for automobiles, durability of coatings, particularly rainfall due to acid rain, and scratches due to car wash brushes and sand particles soaring during traveling are regarded as problems. For example, clear coats for top coats such as car bodies are often made of acrylic resin / melamine resin, but it has become clear that melamine resin causes a decrease in acid resistance. Crosslinking type paints have been proposed (JP-A-63-221123, JP-A-63-221123).
-108048). However, these paints are expensive compared to melamine-based thermosetting paints, and have a problem of poor adhesion to the melamine-based thermosetting paints.

[0003] Among acrylic resins, acrylic polyols obtained by copolymerizing a monomer having a hydroxyl group have been applied to a room temperature curing or baking curing coating compounded with a crosslinking agent capable of reacting with a hydroxyl group, for example, a polyisocyanate or a melamine resin. The acrylic monomer having a hydroxyl group is indispensable for imparting adhesion to a coating film and gasoline resistance. As such a monomer having a hydroxyl group, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and the like have been conventionally used. Here, (meth) acrylic acid represents acrylic acid or methacrylic acid. However, since the hydroxyl groups of the acrylic polyol obtained by copolymerizing these monomers are located very close to the main chain of the rigid acrylic resin skeleton, the reactivity with the crosslinking agent is not sufficient. For these purposes, 4-hydroxybutyl acrylate has been proposed, but its reactivity is still not sufficient.

[0004] As a solution to such a problem, conventionally, abrasion resistance has been obtained, for example, by copolymerizing a hydroxyalkyl (meth) acrylic acid ester obtained by addition reaction of ε-caprolactone with another vinyl monomer. It is known that a clear coat using ε-caprolactone-modified acrylic resin and a melamine curing agent is applied (Japanese Patent Laid-Open No. 66274/1988). There is known a curing agent which employs a clear coat in which a reaction between a carboxylic acid and an epoxy is used in combination (Japanese Patent Application Laid-Open No. 4-114069).

However, in the technique disclosed in Japanese Patent Application Laid-Open No. Sho 66-66274, the lactone-modified (meth) acrylate has a wide lactone chain distribution and a high lactone chain number (n).
When the hardness is increased, the curing reactivity and the flexibility are improved, but the hardness and the acid resistance may be reduced. For example, when a hydroxyalkyl acrylate or hydroxyalkyl methacrylate obtained by addition reaction of ε-caprolactone having a large number of lactone chains is used as a raw material for an automotive topcoat, the hydroxyl value per unit weight of the product is reduced. In order to adjust the hydroxyl value, it is necessary to use a large amount, which may impair other requirements such as gloss and acid resistance other than scratch resistance. In addition, in order to adjust the hydroxyl value without charging a large amount of lactone-modified hydroxyalkyl methacrylate, adjustment may be made with hydroxyethyl methacrylate or hydroxyethyl acrylate. The proportion of n = 1 lactone single-chain hydroxyalkyl (meth) acrylic ester having a good balance between properties and hardness is reduced.

[0006] On the other hand, the technique disclosed in Japanese Patent Application Laid-Open No. 4-114069 can provide a coating film having excellent acid resistance, but has insufficient scratch resistance. In addition, it is known that increasing the glass transition temperature of the cured coating film of the clear coat of the outermost layer is an effective method for obtaining a higher acid resistance. There has been a problem that undesirable situations such as a decrease in not only scratch resistance but also bending resistance and adhesion during recoating are caused. Therefore,
It has been an extremely difficult technique to obtain a coating film that balances acid resistance and abrasion resistance at a high level and also has excellent bending resistance and recoat adhesion.

[0007]

The problem to be solved by the present invention is to provide a cured coating composition having improved acid resistance and a good balance between scratch resistance and acid resistance even if it is an inexpensive melamine curing system. It is to provide things.

[0008]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that hydroxyalkyl (meth) acrylic acid having a reduced proportion of monomers having two or more lactone chains (n ≧ 2) has been obtained. A curable resin composition containing, as essential components, 0.5 to 80 parts by weight of an acrylic polyol resin (A) and 0.5 to 50 parts by weight or more of a melamine resin (B) obtained using an ester composition satisfies the above-mentioned requirements. The present invention was found to be satisfied, and the present invention was completed. That is, in the first aspect of the present invention, the proportion of a monomer having two or more lactone chains (n ≧ 2) represented by the following general formula (1) is 50% (GP
(C area%) Acrylic polyol resin (A) comprising at least a low lactone-modified hydroxyalkyl (meth) acrylate composition (a) in the polymerization component
0.5 to 80 parts by weight and melamine resin (B) 0.5 to
50 parts by weight of a curable resin composition (provided that (A)
And (B) do not exceed 100 parts by weight).

Embedded image Wherein R, R ¹ , R ² and R ³ are independently hydrogen or a methyl group, j is an integer of 2 to 6, and xn R ⁴ and R ⁵ are independently hydrogen. Or 1 to 12 carbon atoms
Wherein x is 4 to 7, n is 0 or an integer of 1 or more, and the average value of n in the composition is 0.3 or more.
It is less than 0. A second aspect of the present invention is the method according to the first aspect, wherein the low lactone-modified hydroxyalkyl (meth) acrylate composition (a) is obtained by using hydroxyethyl (meth) acrylate. A curable resin composition is provided. Thirdly, the low lactone-modified hydroxyalkyl (meth) acrylate composition (a) is obtained by using ε-caprolactone, δ-valerolactone, γ-butyrolactone, or a mixture thereof as a lactone monomer. The curable resin composition according to any one of the first and second aspects of the present invention is provided. Fourth of the present invention
Is an acrylic polyol resin (A) having a low lactone-modified hydroxyalkyl (meth) acrylate composition (a) of 5 to 70 parts by weight and an alkyl (meth) acrylate having an alkyl group of 1 to 20 carbon atoms of 0 to 90. Parts by weight,
0 to 30 parts by weight of (meth) acrylic acid and 0 to 40 parts by weight of another polymerizable unsaturated monomer according to the first to fifth aspects of the present invention.
3. The curable resin composition according to any one of 3. Fifth, the acrylic polyol resin (A) has a hydroxyl value of 5 to 250 and a number average molecular weight of 3,000 to 300,0.
The curable resin composition according to any one of the first to fourth aspects of the present invention, which is 00.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Low lactone modification in which the proportion of a monomer having two or more lactone chains (n ≧ 2) represented by the general formula (1) used in the present invention is less than 50% (GPC area%) Hydroxyalkyl (meth) acrylate composition (a)
Is obtained by subjecting a lactone to ring-opening polymerization of a hydroxyalkyl (meth) acrylate. In producing the composition (a), the composition is obtained by reacting the hydroxyalkyl (meth) acrylate and the lactone monomer at a reaction molar ratio of more than 1. More specifically, the composition (a) is prepared by mixing lactone and hydroxyalkyl (meth) acrylate in an atmosphere containing oxygen at 1000 pp.
m and a composition obtained by reacting at a temperature of about 80 to about 140 ° C. in the presence of less than 1000 ppm of an inhibitor to prevent polymerization of the hydroxyalkyl (meth) acrylate and less than 1000 ppm of the hydroxyalkyl (meth) acrylate.

In obtaining the composition (a) used in the present invention, a hydroxyalkyl (meth) acrylate such as hydroxyethyl acrylate (HEA) or hydroxyethyl methacrylate (HEMA) is used to reduce the lactone chain. The reaction is carried out with the molar ratio of lactone charged to less than 1. The catalyst that can be used in the present invention is various organic and inorganic metal compounds. Preferred catalysts are stannous chloride and monobutyltin tris-2-.
Tin-based compounds such as ethyl hexanate, stannous octoate, and dibutyltin dilaurate. As a result, a composition (a) having a reduced lactone chain useful for the synthesis of a lactone-modified acrylic polyol can be produced. While reducing the lactone chain, unreacted HEA and HEMA will remain, but HEA and HEMA
Is often used alone, and if it is 50% by weight or less, a mixed monomer is often acceptable.

Conventionally, ring-opening polymerization of ε-caprolactone to a substance having a hydroxyl group is performed by adding a titanium-based catalyst such as tetrabutyl titanate, tetraethyl titanate, tetrapropyl titanate or the like at 130 to 230 ° C. Ring-opening polymerization, the addition of ε-caprolactone to a (meth) acrylic ester having a hydroxyl group at a temperature of 130 ° C. or higher results in thermal polymerization of the acrylic ester itself, and It is difficult to get. At a temperature lower than 130 ° C., polymerization of the acrylate itself can be prevented, but the ring-opening reaction rate of ε-caprolactone is very slow.

[0012] Titanium-based catalysts have relatively high activity and can obtain the desired product. However, since this catalyst is also very active as a transesterification catalyst, the transesterification reaction proceeds during the reaction, Alkyl acrylate or hydroxyalkyl methacrylate 2
The polyhydric alcohol is removed from the mole, and hydroxyalkyl diacrylate or hydroxyalkyl dimethacrylate is by-produced. Since such a diacrylate or dimethacrylate has a high boiling point, it is difficult to separate it from a target substance. When the target product containing these by-products is radically copolymerized with another acrylate ester in a solvent, the resin undergoes three-dimensional cross-linking, resulting in a remarkable increase in viscosity or even gelation. . Because of this, the catalytic activity is strong and 80
It is desirable to use a catalyst in which the reaction proceeds sufficiently with a low temperature of about 130 ° C. and a small amount of the catalyst, and which has a small amount of diacrylate or dimethacrylate by-produced by the transesterification reaction. From such a viewpoint, stannous halide, monobutyltin tris-2-ethylhexanate,
A catalyst such as stannous octoate or dibutyltin dilaurate is used.

Among the above-mentioned catalysts, the use of monobutyltin tris-2-ethylhexanate can further reduce the coloration and reduce the transesterification reaction.
The catalyst concentration can be increased, and the reaction time is very excellent and more preferable. When this catalyst is used, the amount of addition is 1 to 1000 ppm, preferably 10 to 5 ppm.
00 ppm.

The hydroxyalkyl (meth) acrylate usable in the production of the composition (a) includes 2-hydroxyalkyl (meth) acrylate.
Hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate, 1,4-butylene glycol monomethacrylate, 1,4-butylene glycol monoacrylate, and the like. Can be

The lactone is used in an amount of from 0.3 to less than 1.0 mol, preferably from 0.35 to less than 1 mol, more preferably from 0.5 to 1 mol, per mol of the hydroxyalkyl acrylate or hydroxyalkyl methacrylate.
0.75 mol of the reaction. If the reaction amount of lactone is large,
The number of lactone chains increases, and when used as a coating material, for example, the curing reactivity and flexibility are improved, but the hardness and acid resistance of the cured product are reduced. On the other hand, if it is smaller than 0.3, the scratch resistance becomes poor. However, in practice, when 1 mole of lactone is reacted with 1 mole of hydroxyalkyl methacrylate, the rate of ring-opening reaction of lactone to the hydroxyl group of hydroxyalkyl methacrylate and the reaction of the product with the hydroxyl group at the terminal of caprolactone are reduced. Since the lactone ring-opening reaction rate hardly changes, the reactant is a compound represented by the above formula (2).

The reaction composition is statistically distributed from the unreacted material of n = 0 to the polycaprolactone of n = 1, 2, 3, 4, 5,... Here, n is preferably 2 or less, the average value of n in the composition is 0.3 or more,
Preferably it is less than 1.0. However, since it is industrially difficult to separate and purify these, in order to reduce the production amount of those having two or more chains, the charged reaction amount of ε-caprolactone per mole of hydroxyalkyl acrylate or hydroxyalkyl methacrylate is considered. To less than one. Further, besides ε-caprolactone, trimethylcaprolactone, δ-valerolactone, γ
-Other cyclic lactones such as butyrolactone may be partially used in combination.

The reaction temperature is 80-150 ° C., preferably 1
00-140 ° C. If the temperature is lower than 80 ° C, the reaction is slow,
When the temperature is higher than 150 ° C., thermal polymerization of acrylic occurs during the reaction, and there is a risk of gelation. It is preferable to add a polymerization inhibitor to the reaction system. As the polymerization inhibitor, hydroquinone, hydroquinone monomethyl ether, phenothiazine and the like are used in an amount of 0.01 to 1%, preferably 0.03 to 0.1%.
Use in the range of 5%. When an inert gas such as nitrogen is passed through the reaction system, radical polymerization is likely to occur. Therefore, passing a gas at all or passing air or the like helps to prevent thermal polymerization of a reactant.

The lactone-modified hydroxyalkyl (meth) acrylic acid ester composition produced by the above production method according to the present invention has a residual lactone content of 0 to 10% by weight and a residual hydroxyalkyl (meth) acrylic acid An ester content of 20% to 50% by weight, a di (meth) acrylate by-product content of 2% by weight or less, Michael addition, acrylic polymerization,
The content of by-products obtained from transesterification or other side reactions is 10% by weight or less, and the content of catalyst is 100% or less.
It is less than 0 ppm, and the content of the polymerization inhibitor is 1% or less.

The composition (a) used in the present invention is used alone,
Or, by copolymerizing with another radical polymerizable monomer, it is possible to provide an acrylic polyol resin having excellent reactivity with a cross-linking agent and rich in flexibility, and the curable resin composition for a paint of the present invention can be provided. It can be applied as material for objects.

Other radically polymerizable monomers copolymerized with the composition (a) used in the present invention include an isocyanate group-containing unsaturated monomer, an active hydrogen-containing polymerizable monomer, and other polymerizable unsaturated monomers.

Other polymerizable unsaturated monomers include:
The following are exemplified. Examples of (meth) acrylates include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylate.
Such as butyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl (meth) acrylate C1-C20 alkyl or cyclic alkyl esters of (meth) acrylic acid; methoxybutyl (meth) acrylate, methoxyethyl (meth) acrylate,
Examples thereof include alkoxyalkyl esters of (meth) acrylic acid having 2 to 8 carbon atoms, such as ethoxybutyl (meth) acrylate. Other than (meth) acrylates, for example, glycidyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene, (meth) acrylonitrile, (meth) acrolein, butadiene, isoprene, (meth) acrylic acid, etc. And these can be used as a mixture.

Examples of the active hydrogen-containing polymerizable monomer include the following hydroxyl group-containing (meth) acrylates and amino group-containing (meth) acrylates, and these can be used in combination. Examples of the hydroxyl group-containing (meth) acrylic acid ester include (meth) acrylic acid having 2 to 8 carbon atoms, such as hydroxyethyl (meth) acrylic acid ester and hydroxypropyl (meth) acrylic acid ester. ,
These can be used in combination. Examples of the amino group-containing (meth) acrylate include (meth) acrylates such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate.
Aminoalkyl esters of acrylic acid; (meth) acrylamide, etc., and these can be used as a mixture.

As the isocyanate group-containing monomer,
For example, isocyanate ethyl (meth) acrylate, isocyanate propyl (meth) acrylate, isocyanate butyl (meth) acrylate, isocyanate hexyl (meth) acrylate, m-isopropenyl-α, α′-dimethylbenzyl isocyanate , M-ethylenyl-α, α′-dimethylbenzyl isocyanate, and the like. Further, a polyisocyanate compound such as hexamethylene diisocyanate is added to the active hydrogen-containing polymerizable monomer such as hydroxyethyl (meth) acrylate. And unsaturated compounds, which can be used in combination. The above radical polymerizable monomers can be used as a mixture, and are selected and used depending on desired physical properties.

The acrylic polyol resin used in the present invention is produced by radically polymerizing the composition (a) and the above-mentioned radically polymerizable monomer in the presence of a radical polymerization initiator by a known solution polymerization method. Examples of the radical polymerization initiator include benzoyl peroxide, t-butyl hydroperoxide, cumyl hydroperoxide, cumene hydroperoxide, t-butylperoxybenzoate, t-butylperoxy-2-ethylhexanoate and the like. And azo-based initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile. Solvents used for solution polymerization include, for example, benzene, toluene, xylene; butyl acetate, ethyl acetate, propyl acetate, ester systems such as cellosolve acetate; dioxane, ether systems such as ethylene glycol dibutyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone Solvents such as a system, and these can be used alone or in combination of two or more.

The composition ratio of the obtained acrylic polyol resin (A) is such that the low lactone-modified hydroxyalkyl (meth)
Acrylic ester composition (a) 5 to 70 parts by weight, alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms 0 to 90 parts by weight, (meth) acrylic acid 0 to 30
Parts by weight, and from 0 to 40 parts by weight of the other polymerizable unsaturated monomer. The acrylic polyol resin (A) has a hydroxyl value of 5 to 250 and a number average molecular weight of 3,000 to 300,00.
0.

As the reactor used for the above polymerization, a reactor equipped with a stirrer, a reflux condenser with a drying tube, and a twin-screw extruder are preferably used. Polymerization temperature, polymerization time, the lactone-modified hydroxyalkylacrylic acid or methacrylic acid ester composition of the present invention and the respective types of the radical polymerizable monomers, the charging ratio, the type and amount of the catalyst, and further depending on the reaction device, There is no particular limitation, and the desired curable oligomer or (co)
It is appropriately determined depending on the use of the polymer acrylic resin, the physical properties of the coating film required for the paint, and the like.

As the melamine resin (B) used in the present invention, an ordinary melamine resin for coatings can be used as it is, and an imino-type or methylol-type melamine resin is used. Since no isocyanate compound is used as a curing agent, the handling and safety of the paint are excellent. The imino-type or methylol-type melamine resin is not particularly limited, and may react with a hydroxyl group.
As long as it is used in a paint system using such a hydroxyl group as a functional group, it can be used without particular limitation. Such imino-type melamine resins include, for example, Uban 22R (solid content 60%), Yuban 21R (solid content 50%), and Yuban 2028 (solid content 75%) manufactured by Mitsui Chemicals.
(All are imino-type melamine resins) and the like. On the other hand, as the methylol-type melamine resin, melamine and formaldehyde, a monoalcohol having 1 to 4 carbon atoms, and in some cases, a melamine resin having a degree of condensation of about 1.1 to 20 using water as a raw material can be used. For example, Uban manufactured by Mitsui Chemicals
60R (solid content 50%) and Super Beckamine L-121-60 (60% solid content) manufactured by Dainippon Ink and Chemicals, and the like.

The curable resin composition of the present invention comprises an acrylic polyol resin (A) obtained by using the composition (a).
0.5 to 80 parts by weight and melamine resin (B) 0.5 to
It contains 50 parts by weight as an essential component. However, (A)
And (B) do not exceed 100 parts by weight. If the amount of the acrylic polyol resin (A) is less than 0.5 part by weight, the bending resistance becomes insufficient, and if it exceeds 80 parts by weight, the abrasion resistance decreases, which is not preferable. If the amount of the melamine resin (B) is less than 0.5 part by weight, the solvent resistance is not sufficient, and if it exceeds 50 parts by weight, the acid resistance becomes insufficient, which is not preferable. When the use ratio of the acrylic polyol resin (A) and the melamine resin (B) is expressed separately, the acrylic polyol resin (A) 4
Melamine resin (B) 60-1 based on 0-90% by weight
0% by weight. When the use ratio of the acrylic polyol resin (A) is less than 40% by weight, the self-condensation reaction between the melamines increases, and the coating film becomes brittle. For example, it is not suitable as a paint for a polyolefin resin molded article. . On the other hand, when the use ratio of the acrylic polyol resin (A) is more than 90% by weight, crosslinking becomes insufficient,
Solvent resistance and weather resistance decrease. A preferred use ratio of the acrylic polyol resin (A) is 60 to 80% by weight, and a use ratio of the melamine resin (B) is 40 to 20% by weight.

In the present invention, the total acid value of the acrylic polyol resin (A), melamine resin (B) and, if necessary, the acidic curing catalyst is 5 to 50, preferably 15 to 35. If the total acid value is less than 5, crosslinking reactivity decreases, crosslinking becomes insufficient, and gasoline resistance and weather resistance decrease. On the other hand, when the acid value is higher than 50, the storage stability decreases and the water resistance decreases. By adjusting the acid value in this way, the coating composition can be made low-temperature curable.
To give the acrylic polyol resin (A) an acid value,
A monomer having an acid value such as a carboxyl group or a phosphoric acid group may be used in combination as a vinyl polymerizable monomer, and the acid group may be introduced into the acrylic polyol resin (A). The acid value can also be adjusted by blending an acidic curing catalyst into the coating composition. As such an acidic curing catalyst, a weakly acidic catalyst is used. Examples of such a weakly acidic catalyst include phosphoric acids, phosphoric acid monoesters, phosphites, unsaturated group-containing phosphates, carboxylic acids, and the like. As the weakly acidic catalyst, phosphoric acids or esters thereof are particularly preferred. Examples of such phosphoric acids or esters thereof include phosphoric acid, pyrophosphoric acid, and the like, and phosphoric acid mono- or diesters. Examples of the phosphoric acid monoester include monooctyl phosphate, monopropyl phosphate, monolauryl phosphate and the like. Examples of the phosphoric diester include dioctyl phosphate, dipropyl phosphate, dilauryl phosphate and the like. Furthermore, mono (2- (meth) acryloyloxyethyl) acid phosphate is mentioned. Further, a compound obtained by reacting a compound containing an acid anhydride with a polyol or an alcohol may be used. Further, an oligomer having an acid value may be blended. In this case, as a method for introducing an acid value into the acrylic polyol resin (A) and the other oligomer, for example, when graft polymerization or (co) polymerization is performed, a vinyl polymerizable monomer having a carboxyl group or a phosphate group may be used. There are ways to use it. In addition, it is preferable that the carboxyl group or the phosphoric acid group is present at a position away from the main chain of the oligomer by 10 atoms or more, and it is easy to react at a low temperature.

The acidic curing catalyst is based on the total weight of the acrylic polyol resin (A) and the melamine resin (B).
It is 0.001 to 10% by weight, preferably 0.001 to 5% by weight.

The coating composition of the present invention can be used as it is or, if necessary, with various additives conventionally used in the field of coatings, for example, coloring pigments, extender pigments, aluminum powder, pearl mica powder, A coating composition can be prepared by appropriately blending an anti-sagging agent or an anti-settling agent, a leveling agent, a dispersant, an antifoaming agent, an ultraviolet absorber, a light stabilizer, an antistatic agent, and a thinner.

Examples of the coloring pigment include titanium oxide (for example, Taipaque CR-95 (a titanium oxide pigment manufactured by Ciba Geigy)), carbon black, iron oxide, red iron oxide,
Inorganic pigments such as lead molybdate, chromium oxide and lead chromate, phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, quinacridone red, azo pigments,
Organic pigments such as anthraquinone pigments are exemplified.

Examples of the extender include kaolin and
Examples include talc, silica, mica, barium sulfate, calcium carbonate and the like. As the anti-sagging agent or the anti-settling agent, for example, bentonite, castor oil wax, amide wax, microgel (for example, MG100S (manufactured by Dainippon Ink)), aluminum acetate and the like can be preferably used.

As the leveling agent, for example, KF69, Kp
Silicon-based surfactants such as 321 and Kp301 (above, manufactured by Shin-Etsu Chemical), silicon-based surfactants such as Modaflow (a surface conditioner manufactured by Mitsubishi Monsanto), BYK301 and 358 (manufactured by Big Chemie Japan), and diamond aids AD9001 (manufactured by Mitsubishi Rayon) or the like can be preferably used. As dispersants, for example, Anti-Terra U or Anti-Terra P and
Disperbyk-101 (all manufactured by Big Chemie Japan) and the like can be preferably used. As the antifoaming agent, for example, BYK-0 (manufactured by BYK Japan) can be preferably used. As the ultraviolet absorber, for example,
Benzotriazole UV absorbers such as Tinuvin 900, Tinuvin 384, Tinuvin P (all manufactured by Ciba Geigy),
An oxalic acid anilide ultraviolet absorber such as Sandbar 3206 (manufactured by Sandwich) can be preferably used. As the light stabilizer, for example, hindered amine light stabilizers such as SANOL LS292 (manufactured by Sankyo) and Sandbar 3058 (manufactured by Sando) can be preferably used.

Examples of the thinner include aromatic compounds such as toluene, xylene and ethylbenzene, alcohols such as methanol, ethanol, propanol, butanol and isobutanol, acetone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, isophorone, and the like. Ketones such as N-methylpyrrolidone, ethyl acetate,
Ester compounds such as butyl acetate and methyl cellosolve, and mixtures thereof can be used. As the antistatic agent, for example, Esocard C25 (manufactured by Lion Armor) or the like can be preferably used. In preparing the coating composition of the present invention, the acrylic polyol resin (A), the melamine resin (B), and additives such as an acid dissociation catalyst and a pigment, if necessary, are mixed, and then mixed with a sand grind mill, a ball mill, By uniformly dispersing with a disperser such as an attritor, the (cured coating composition) of the present invention is prepared.

The curable resin composition (paint composition) of the present invention
First, a known degreasing and cleaning treatment, for example, degreasing and cleaning with an organic solvent such as 1,1,1-trichloroethane, alkali degreasing, acid cleaning, solvent wipe, etc. Also, if necessary, in order to further improve the adhesion of the paint to the object to be coated, for example,
After applying a primer such as Primac N0.1500 (manufactured by Nippon Oil & Fat), the coating composition of the present invention is directly applied by air atomization coating, airless coating, or the like.
0 minutes, preferably after setting for 1 to 20 minutes, 90 to 140 ° C,
Heat curing (baking) is preferably performed at a low temperature of 100 to 120 ° C. The clear paint may be applied wet-on-wet to the base coat paint constituting the lower layer.
In the present invention, with the above configuration, it is possible to heat and cure at a low temperature of 140 ° C. or less, so that a polyolefin-based resin molded article can be coated with a coating having excellent coating properties without damaging the molded article. it can.

When a primer is applied, its thickness is generally 3 to 20 μm, preferably, as a thickness after drying.
5 to 15 μm. Further, the film thickness of the clear paint, as a film thickness after drying, generally 15 to 45 μm, preferably 20 to 35 μm
It is. Examples of a coating method using the coating composition of the present invention include a two-coat one-bake type, a three-coat two-bake type, and the like. Here, the two-coat one-bake type is one of the methods for applying a top coat, in which a base coat paint containing a large amount of pigment and / or metal powder is first applied, and then a transparent clear paint is applied thereon. Alternatively, it is a coating method in which a top coat, which is a color clear paint containing less pigment, is applied and baked at a time. In the case of the above-mentioned two-coat one-bake-type coating method, an ordinary coating composition can be used as the base coat coating, and the coating composition of the present invention can be used for the top coat. 3 coat 2 bake type, apply paint containing blended materials, dyes and / or metal powders, bake, apply a base coat further blended pigments, dyes and / or metal powders, and then This is a coating method in which a transparent clear paint or a top coat which is a color clear paint having a small amount of pigments or dyes is applied thereon and baked at a time.

[0038]

Next, the present invention will be described more specifically with reference examples, examples, and comparative examples, but the present invention is by no means limited to these examples. In the following examples, all parts and percentages are by mass unless otherwise specified. Reference Example 1 In a four-necked flask equipped with an air inlet tube, a thermometer, a cooling tube, and a stirrer, 2446 parts of 2-hydroxyethyl methacrylate (2-HEMA) and ε-caprolactone (ε) were placed.
-CL) (1610 parts), 1.99 parts of hydroquinone monomethyl ether (HQME) as a polymerization inhibitor, and 0.199 parts of stannous chloride (SnCl2) as a reaction catalyst were reacted at 100 ° C for 23 hours while passing air. The conversion of ε-caprolactone is 99.4%, and the hue of the reaction product is 2
0 (APHA). When the obtained lactone-modified 2-hydroxyethyl methacrylate composition was copolymerized with another monomer, a good acrylic polyol resin was obtained.

Reference Example 2 In a four-necked flask equipped with an air inlet tube, a thermometer, a cooling tube, and a stirrer, 2446 parts of 2-hydroxyethyl methacrylate (2-HEMA) and ε-caprolactone (ε
-CL) (1610 parts), 1.99 parts of hydroquinone monomethyl ether (HQME) as a polymerization inhibitor, and 0.795 parts of monobutyltin tris-2-ethylhexate as a reaction catalyst.
The reaction was performed for 5 hours. The conversion of ε-caprolactone is 9
The hue of the reaction was 9.4%, 20 (APHA).
When the obtained lactone-modified 2-hydroxyethyl methacrylate was copolymerized with another monomer, a good acrylic polyol resin was obtained (see Reference Example 5).

Reference Example 3 In a four-necked flask equipped with an air inlet tube, a thermometer, a cooling tube, and a stirrer, 2446 parts of 2-hydroxyethyl methacrylate (2-HEMA), ε-caprolactone (ε
-CL) 1073 parts, 1.72 parts of hydroquinone monomethyl ether (HQME) as a polymerization inhibitor, and 0.690 parts of monobutyltin tris-2-ethylhexanate as a reaction catalyst, and react at 100 ° C for 7 hours while passing air. Was. The conversion of ε-caprolactone is 99.6.
%, The hue of the reaction was 30 (APHA). When the obtained lactone-modified 2-hydroxyethyl methacrylate was copolymerized with another monomer, a good acrylic polyol resin was obtained (see Reference Example 6).

REFERENCE EXAMPLE 4 In the same apparatus as in Reference Example 1, 504 parts of 2-hydroxyethyl acrylate (2-HEMA), 248 parts of ε-caprolactone, 0.368 part of hydroquinone monomethyl ether as a polymerization inhibitor, monobutyltin tris -2
-Ethylhexanate (0.148 parts) was charged and reacted at 100 ° C. for 7 hours while passing air through the reaction.
(APHA). When the obtained composition was copolymerized in the same manner as in Reference Example 5, a good acrylic polyol resin was obtained.

REFERENCE COMPARATIVE EXAMPLE 1 In the same apparatus as in Reference Example 1, 2446 parts of 2-hydroxyethyl methacrylate and 2146 of ε-caprolactone were used.
Parts, 2.25 parts of hydroquinone monomethyl ether as a polymerization inhibitor, and monobutyltin tris-2- as a catalyst
0.900 parts of ethyl hexanate was added and reacted at 100 ° C. for 8 hours while passing air. The conversion of ε-caprolactone was 99.0%, and the hue of the reaction product was 25 (APH
A). When the obtained lactone-modified 2-hydroxyethyl methacrylate composition was copolymerized with another monomer, an excellent acrylic polyol resin was obtained (see Reference Comparative Example 7).

REFERENCE COMPARATIVE EXAMPLE 2 In the same apparatus as in Reference Example 1, 799 parts of 2-hydroxyethyl methacrylate, 701 parts of ε-caprolactone were added.
0.735 parts of hydroquinone monomethyl ether and 0.147 parts of tetrabutyl titanate (TBT) were added, and the mixture was reacted at 100 ° C. for 64 hours while passing air.
-The conversion of caprolactone was 99.6% and the hue of the reaction product was 50 (APHA). When the obtained composition was copolymerized in the same manner as in Reference Example 5, the composition thickened during the reaction and eventually gelled, and it was not possible to obtain an acrylic polyol resin.

REFERENCE COMPARATIVE EXAMPLE 3 In the same apparatus as in Reference Example 1, 1816 parts of 2-hydroxyethyl methacrylate, ε-caprolactone 3184
Parts, 2.50 parts of hydroquinone monomethyl ether, 1.00 of monobutyltin tris-2-ethylhexanate
The reaction was carried out at 100 ° C. for 8.5 hours while passing air, and the reaction rate of ε-caprolactone was 99.2.
%, The hue of the reaction was 25 (APHA). When the obtained lactone-modified 2-hydroxyethyl methacrylate composition was copolymerized with another monomer, a good acrylic polyol resin was obtained (see Reference Comparative Examples 9 and 10).

REFERENCE COMPARATIVE EXAMPLE 4 In the same apparatus as in Reference Example 1, 1816 parts of 2-hydroxyethyl methacrylate and ε-caprolactone 4776 were added.
Parts, 3.30 parts of hydroquinone monomethyl ether, 1.32 monobutyltin tris-2-ethylhexanate
The reaction was carried out at 100 ° C. for 8 hours while passing air, and the reaction rate of ε-caprolactone was 99.2%,
The hue of the reaction was 25 (APHA). When the obtained lactone-modified 2-hydroxyethyl methacrylate composition was copolymerized with another monomer, a good acrylic polyol resin was obtained (see Reference Comparative Example 11).

REFERENCE COMPARATIVE EXAMPLE 5 In the same apparatus as in Reference Example 1, 1816 parts of 2-hydroxyethyl methacrylate and ε-caprolactone 6364 were added.
Parts, hydroquinone monomethyl ether 4.10 parts, monobutyltin tris-2-ethylhexanate 1.64
The reaction was carried out at 100 ° C. for 8.5 hours while passing air, and the reaction rate of ε-caprolactone was 99.2.
%, The hue of the reaction was 30 (APHA). When the obtained lactone-modified 2-hydroxyethyl methacrylate composition was copolymerized with another monomer, a good acrylic polyol resin was obtained.

Note that ε in the above reference example and reference comparative example was used.
-The theoretical molar number of addition of caprolactone is as follows. Reference Example 1: n = 0.75 Reference Example 2: n = 0.7
5, Reference Example 3: n = 0.50, Reference Example 4: n = 0.5
0, Reference Comparative Example 1: n = 1, Reference Comparative Example 2: n = 1, Reference Comparative Example 3: n = 2, Reference Comparative Example 4: n = 3, Reference Comparative Example 5: n = 4 n = 0. 50 for FM 0.5, n = 0.75 for FM 0.75, n = 1 for FM1, n = 2 for FM2, n = 3 for FM3, n = 4 FM
Notated as 4 etc.

The chain distribution of ε-caprolactone from GCP of the composition obtained above is shown in Table 1 and FIG.

[0049]

[Table 1]

Tables 2 and 3 summarize the reaction compositions, reaction conditions, and properties of the reactants of Reference Examples 1 to 4 and Reference Comparative Examples 1 to 5.

[0051]

[Table 2]

[0052]

[Table 3]

Reference Example 5 50 parts of butyl acetate, 50 parts of toluene were placed in a four-necked flask equipped with a thermometer, a reflux condenser, a nitrogen gas inlet, and a stirrer.
Ditertiary butyl peroxide (DTBPO) 1.0
The mixture was heated to 115 ° C., and when the temperature reached 115 ° C., 17.3 parts of styrene, 17.3 parts of butyl methacrylate, 17.3 parts of butyl acrylate,
2.0 parts of methacrylic acid, 46 parts of ε-caprolactone-modified 2-hydroxyethyl methacrylate synthesized in Reference Example 2, 0 parts of 2-hydroxyethyl methacrylate, and 1.0 part of azobisisobutyronitrile for 3 hours. And the reaction was continued for further 4 hours to obtain a good acrylic polyol resin transparent solution (A-1). The raw material composition and the properties of the resin solution are shown in Tables 4 and 5, respectively. Table 6 and FIG. 2 show the relationship between the ε-caprolactone / HEMA charge ratio and the ε-caprolactone chain distribution ratio.

Reference Example 6 and Reference Comparative Examples 6 to 11 The monomer and HEMA of the ε-caprolactone-modified acrylic ester composition obtained in Reference Examples 3 and 1 to 4 were mixed in the same apparatus and under the same mixing conditions as Reference Example 5. When polymerized,
Although a good acrylic polyol resin transparent solution could be obtained from the monomers obtained in Reference Example 3 and Reference Comparative Examples 3 and 4, in the case of the monomer obtained in Reference Comparative Example 2, the reaction solution increased during the polymerization. As a result, a resin solution was not obtained. Tables 4 and 5 show the raw material composition and the properties of the resin solution of each Reference Example and Reference Comparative Example, respectively.
The relationship between the caprolactone / HEMA charge ratio and the ε-caprolactone chain distribution ratio is shown in Table 6 and FIG.

[0055]

[Table 4]

[0056]

[Table 5]

[0057]

[Table 6]

In the polymerization of the acrylic resin, the obtained hydroxyl value (OHV) is set to 120 and the Tg is set to 0 to 10
5 and 6 of the above-mentioned Reference Example set to 7 ° C., 7 of the Reference Comparative Example,
8, 10, and 11, in Reference Examples 5 and 6, the ratio of the single adduct of ε-caprolactone (n = 1) is high, and the hardness of the melamine cured product of the acrylic resin is reduced. It can be seen that the ratio of the adducts of

Embodiment 1 Preparation of Clear Paint A clear paint (C series) was prepared based on the formulation shown in Table 7 below. Comparative clear paint (SC series)
Was prepared based on the formulation shown in Table 7 below. 2． Preparation of solid color paints Solid color paints are prepared by adding titanium oxide to a mixture of the raw material resin and melamine resin, dispersing the mixture with a motor mill (manufactured by Eiger Japan) for 30 minutes, and adding the remaining components. went. Solid color paint (S
Series) were prepared based on the formulations shown in Table 8 below. Comparative solid color paints (RS series) were prepared based on the formulations shown in Table 8 below.

Evaluation of paint performance Preparation of test piece As an object to be coated, a polyolefin resin (X5 manufactured by Mitsui Chemicals, Inc.)
The test piece molded in 0) was washed with isopropyl alcohol, and then washed with petroleum benzene. 2． Coating the test piece (1) In the case of clear paint The test piece is coated with a primer
o. 1500) at a thickness of 15 μm and dried. Primac No. 1 is used as a base coat paint. 5500 (manufactured by NOF CORPORATION), and then the wet-on-wet clear paint was applied to a Ford Cup No. using a mixed thinner of xylene and Solvesso 100. The test piece was diluted with 16 seconds at 4 and air-sprayed wet-on-wet on the test piece so that the dry coating film of the clear paint became 30 μm. After leaving at room temperature for 10 minutes, 120 ° C
For 30 minutes and at 100 ° C. for 30 minutes, and after 24 hours, the characteristics of the coating film were examined. The case where the clear paint was applied without using the primer is as follows. A test piece was coated with the basecoat paint X prepared as described below using a thinner of toluene / ethyl acetate (weight ratio 60/40) in a Ford Cup No. After dilution with 4 for 13 seconds, the resultant was applied with an air spray so that the dry film thickness became 15 μm. Next, the clear paint adjusted as described above was mixed with xylene and Solvesso 100 using a thinner for Ford Cup N.
o. The mixture was diluted to 16 seconds with 4, and air-sprayed on the base coat paint by wet-on-wet so that the dry film thickness of the clear paint was 30 μm. After leaving it to stand at room temperature for 10 minutes, it was dried by heating at 120 ° C. for 30 minutes and at 100 ° C. for 30 minutes, and after 24 hours, the characteristics of the coating film were examined.

Preparation of Basecoat Paint X (a) Preparation of Primary Hydroxyl-Containing Grafted Chlorinated Polyolefin Oligomer X In a four-necked flask equipped with a stirrer, thermometer, inert gas inlet, dropping funnel and reflux device, 494 parts of toluene and 250 parts of Hallen 14ML (chlorinated polyolefin manufactured by Toyo Kasei: chlorine content 26%) were added, and the temperature was raised to 100 ° C. while stirring. Next, a mixed solution of 142 parts of Praxel FM-3, 104 parts of isobornyl methacrylate, 6 parts of benzoyl peroxide and 4 parts of azobisisobutyronitrile was added dropwise over 3 hours, and the reaction was further continued for 6 hours. The above grafted chlorinated polyolefin oligomer X was obtained. (B) Preparation of base coat paint X It was prepared with the following composition.

[0062]

[Table 7]

(2) In the case of solid color paint After the primer was applied to a test piece so that the dry film thickness became 15 μm and dried, the solid color paint prepared as above was mixed with a thinner of xylene and butyl acetate in a Ford cup. No. The test piece was diluted with 16 to 16 seconds, and the test piece was applied by air spray so that the dry coating film of the solid color paint became 30 μm. After leaving at room temperature for 10 minutes, heat and dry at 120 ° C for 30 minutes and 100 ° C for 30 minutes,
After an hour, the coating properties were examined.

2. Performance Evaluation Method (1) Water Resistance Test One part of the coated molded product was immersed in warm water at 50 ° C. for 10 days, taken out, and evaluated for adhesion and the presence or absence of blisters. Here, a sample having many peeling or blisters was marked with “x”, a sample without peeling with few blisters was marked with “△”, and a sample without peeling or blistering was marked with “○”. (2) Gloss retention test An accelerated weather resistance test was performed using a sunshine weatherometer (manufactured by Suga Test Instruments), and a 60-degree mirror gloss after 1000 hours was measured.
The retention rate (%) according to JIS K5400 (1979) was measured, and an adhesion test was performed according to JIS K5400 (1976) 6.15. If the gloss retention is 80% or more and good adhesion, it is ○. If the gloss retention is 70% or more and less than 80%, and the adhesion test is good, △, the gloss retention is less than 70% and What peeled off in the adhesion test was evaluated as x. (3) Gasoline resistance A part of the painted molded product was immersed in regular gasoline (Nippon Oil Nippon Oil Silver Gasoline) at 20 ° C, taken out, and swellability was visually evaluated. X was markedly swollen, Δ was slightly swollen, and O was hardly swollen. (4) Acid Resistance Test 0.2 ml of a 5% sulfuric acid aqueous solution was dropped on the coating film, dried at 40 ° C. for 30 minutes, and the state of the coating film was visually observed. When there was a trace, it was evaluated as x, when there was little trace, it was evaluated as Δ, and when there was no trace, it was evaluated as ○. (5) Paint solids The lower the paint solids, the more difficult it is to make the film thickness. Clear paint and solid color paint, paint solid content 30%
The following were rated as x, those exceeding 30% and 35% or less were rated as △, those exceeding 35% and 40% or less were rated as ○, and those exceeding 40% were rated ◎. These characteristics data are combined together with Table 8 above.
-9.

[0065]

[Table 8]

[0066]

[Table 9]

[0067]

[Table 10]

[0068]

[Table 11]

From the above Examples and Comparative Examples, when those having a small proportion of these two or more ε-caprolactone adducts are used, for example, as a coating material for an automobile top coat, the hardness of the coating film, the finished appearance, It is clear that a coating film having a good balance of weather resistance, acid resistance, stain resistance, gloss, and scratch resistance can be formed.

[0070]

According to the present invention, the curable coating composition using a lactone-modified monomer having a reduced lactone chain has improved acid resistance, acid resistance and abrasion resistance even if it is an inexpensive melamine curing system. Provides a coating film that balances at a high level and is excellent in bending resistance and recoat adhesion.

[Brief description of the drawings]

FIG. 1 shows ε in Reference Examples 1 to 4 and Reference Comparative Examples 1 to 5.
-Shows the chain distribution of caprolactone.

FIG. 2 shows ε in Reference Examples 5 to 6 and Reference Comparative Examples 7 to 11.
The relationship between the caprolactone / HEMA charge ratio and the ε-caprolactone chain distribution ratio is shown.

Claims (5)

[Claims] 1. A lactone 2 represented by the following general formula (1)
Low lactone-modified hydroxyalkyl (meth) having less than 50% (GPC area%) of monomer of chain or more (n ≧ 2)
Acrylic polyol resin (A) containing acrylic ester composition (a) at least as a polymerization component
A curable resin composition comprising 0 parts by weight and 0.5 to 50 parts by weight of a melamine resin (B) (however, the total of (A) and (B) does not exceed 100 parts by weight). Embedded image Wherein R, R ¹ , R ² and R ³ are independently hydrogen or a methyl group, j is an integer of 2 to 6, and xn R ⁴ and R ⁵ are independently hydrogen. Or 1 to 12 carbon atoms
Wherein x is 4 to 7, n is 0 or an integer of 1 or more, and the average value of n in the composition is 0.3 or more.
It is less than 0. ) 2. The curable resin composition according to claim 1, wherein the low lactone-modified hydroxyalkyl (meth) acrylate composition (a) is obtained by using hydroxyethyl (meth) acrylate. 3. A low lactone-modified hydroxyalkyl (meth) acrylate composition (a) comprising lactone monomers such as ε-caprolactone, δ-valerolactone,
The curable resin composition according to claim 1, which is obtained by using γ-butyrolactone or a mixture thereof. 4. The acrylic polyol resin (A) is a low lactone-modified hydroxyalkyl (meth) acrylate composition (a) in an amount of 5 to 70 parts by weight and an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms. 0-9
The curable resin composition according to any one of claims 1 to 3, comprising 0 parts by weight, 0 to 30 parts by weight of (meth) acrylic acid, and 0 to 40 parts by weight of another polymerizable unsaturated monomer. 5. The acrylic polyol resin (A) has a hydroxyl value of 5 to 250 and a number average molecular weight of 3,000 to 300,0.
The curable resin composition according to any one of claims 1 to 4, which is 00.