JPH06220398A - Coating composition having high solid content - Google Patents

Abstract

PURPOSE:To effectively reduce an amount of a solvent in a coating material without damaging characteristics of the coating material. CONSTITUTION:This coating composition having a high solid content comprises a first component composed of a polyester oligomer having <=2,000 number- average molecular weight obtained by reacting a tri- or polyfunctional hydroxyl group-containing compound having <=200 molecular weight with an acid anhydride compound to give a compound and reacting this compound with a monofunctional epoxy compound and a second component composed of a curing agent having reactivity with hydroxyl group as essential components.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention has a high solid content capable of forming a coating film having excellent scratch resistance without impairing the fluidity of the coating material and reducing the amount of solvent in the coating material. The present invention relates to a coating composition.

[0002]

2. Description of the Related Art In recent years, in order to prevent pollution of the environment due to vaporization of a solvent constituting a paint, for example, as shown in JP-A-61-9461, hydroxyl group-containing polymers and fine particle weights are used. A high solid coating composition has been proposed which is configured to reduce the amount of solvent in the coating material while maintaining the coating workability in a good state by blending a specific amino resin in a system consisting of coalesced products. There is.

[0003]

The high solid coating composition disclosed in the above publication is capable of reducing the amount of solvent to some extent while imparting appropriate fluidity to the coating so that the coating operation is easy. However, its scratch resistance and acid resistance were insufficient, and it was not satisfactory as a coating composition used outdoors for automobiles and the like.

Further, as a top coating composition for automobiles having excellent gloss, hardness, durability, solvent resistance, water resistance, low temperature property and rapid curing property, JP-A-55-1236.
As shown in JP-A-60, a thermosetting coating composition for coating containing an appropriate amount of acrylic resin is known.

In order to obtain proper paint properties in the paint containing the acrylic resin as described above, 2000
It is necessary to use an acrylic resin having the above molecular weight. Therefore, in order to impart plasticity to the coating by appropriately plasticizing the acrylic resin, a certain amount of solvent must be used, and the effect of reducing the amount of solvent contained in the coating is insufficient. There was a problem.

The present invention has been made to solve the above problems, and provides a high solids coating composition capable of effectively reducing the amount of solvent in the coating without impairing the characteristics of the coating. The purpose is to do.

[0007]

The present invention according to claim 1 provides a compound (a) obtained by reacting a compound (a) having a trifunctional or higher functional hydroxyl group with a molecular weight of 200 or less and a compound (b) of an acid anhydride. In c), a monofunctional epoxy compound (d)
A high-solids coating composition containing as an essential component a first component consisting of a polyester oligomer having a number average molecular weight of 2000 or less obtained by reacting the above and a second component consisting of a curing agent having reactivity with a hydroxyl group. Is.

The high solids coating composition of the present invention will be described in more detail below. Here, as the compound (a) having a trifunctional or higher functional hydroxyl group constituting the first component, for example, glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, tris (2-hydroxyethyl) isocyanurate. Such as triols, pentaerythritol, dipentaerythritol, inositol and the like.

As described above, a compound having a trifunctional or higher functional hydroxyl group is used as the compound (a) constituting the first component, because the use of a bifunctional or lower functional compound results in insufficient crosslinking of the resin. This is because the film thickness cannot be formed sufficiently.

Examples of the compound (b) which is an anhydrous compound to be reacted with the above compound (a) include phthalic anhydride,
Examples include hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, hettic anhydride, hymic acid anhydride, trimellitic anhydride, and the like.

The monofunctional epoxy compound (d) which is reacted with the compound (c) obtained by reacting the compound (a) with the compound (b) which is an anhydrous compound is, for example, a product of Showa Shell Sekiyu KK Name "Currager E10", "Pes 10", product name "AOEX" from Daicel Chemical Industries, Ltd.
24 ”or the same“ AOEX68 ”.

The number average molecular weight of the first component consisting of the polyester oligomer obtained by reacting the compound (c) with the monofunctional epoxy compound (d) is 200.
It is preferably 0 or less and more preferably 1000 or less. The number average molecular weight of the first component is limited to 2000 or less,
This is because when the number average molecular weight is 2000 or more, it becomes difficult to dilute with a solvent and the effect of reducing the solvent of the paint cannot be obtained.

Examples of the curing agent which reacts with the hydroxyl group as the second component include isocyanate prepolymers, melamine resins, oligomers containing acid anhydrides and oligomers containing silanol groups.

Examples of the above-mentioned isocyanate prepolymer include aliphatic isocyanates such as hexahydrodiisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate and isophorone diisocyanate, or isocyanurates of alicyclic isocyanates, trimethylolpropane adducts or burettes. Can be mentioned.

The above melamine resin is classified into a mononuclear type and a polynuclear type, and it is effective to use a mononuclear type melamine resin in order to achieve the object of the present invention of reducing the solvent. As a specific example of this melamine resin, for example, "Cymel 30" manufactured by Mitsui Cyanamide Co., Ltd.
3 ”, the same“ Cymel 370 ”and the like.

The acid anhydride-containing oligomer is obtained by polymerizing a monomer having a vinyl group and an acid anhydride group, such as maleic anhydride or succinic anhydride, and a copolymerizable monomer. By doing so, an acrylic copolymer is obtained. The number average molecular weight of this acrylic copolymer is in the range of 800 to 1500, and 900 to 120
The range of 0 is preferable. If the number average molecular weight is less than 800, crosslinking of the resin will be insufficient and the chemical resistance of the coating will be poor. If it exceeds 1500, the molecular weight of the resin will be high and the viscosity of the coating will increase. This is because the effect of reducing the solvent decreases.

The ratio of the weight average molecular weight to the number average molecular weight of the acrylic copolymer is suitably 2.5 or less, preferably 2 or less. This is because if the ratio exceeds 2.5, molecules having an extremely high molecular weight are present in the resin, the viscosity of the coating material increases, and the solvent reduction effect cannot be expected.

The silanol group-containing oligomer is obtained by copolymerizing a silanol group-containing monomer represented by the following general formula 1 with a copolymerizable monomer to obtain an acrylic polymer. Can be obtained as

[0019]

[Chemical 1]

In the general formula shown in the above chemical formula 1, R
1 is H or CH ₃ , A is an ester or benzene ring, R 2 is a divalent saturated aliphatic hydrocarbon having 1 to 6 carbon atoms, R ₃ and 4 are the same or different phenyl groups, and 1 to 6 carbon atoms Is an alkyl group, an alkoxy group or an acyloxy group, R5 is H or an alkyl group having 1 to 6 carbon atoms, n
Is an integer of 1 to 10.

Examples of the divalent aliphatic saturated hydrocarbon having 1 to 6 carbon atoms represented by R2 include linear or branched alkylene groups such as methylene, ethylene, propylene and hexamethylene. . The alkyl group having 1 to 6 carbon atoms represented by R3, R4 and R5 is a linear or branched alkyl group such as methyl, ethyl, propyl, isobutyl, n-butyl, sec-butyl, pentyl. , Neopentyl group and the like.

The carbon number represented by R3 and R4 is 1
As the alkoxy group of to 6, linear or branched alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, n
-Pentoxy, n-hexyloxy and the like can be mentioned. When the integer n is 2 or more, R3 and R4 may be different from each other or may be the same.

In the present invention, the compound used as a monomer represented by the general formula of the above chemical formula 1 is, for example, γ- (meth) acryloxypropyltrimethoxysilane γ- (meth) acryloxypropyltrisilanol γ. -(Meth) acryloxypropyltrimethoxysilane γ- (meth) acryloxypropyltrisilanediol γ- (meth) acryloxybutylphenylsilanediol γ- (meth) acryloxypropylmethyldipropoxysilane Typical examples of the monomers copolymerizable with are alkyl (meth) acrylate, which is an ester compound of an alkyl group having 1 to 22 carbon atoms and (meth) acrylic acid, styrene, vinyltoluene, ter.
-Butyl styrene, glycidyl (meth) acrylate,
2-Ethoxyethyl (meth) acrylate, (meth) acrylonitrile, cyclohexyl (meth) acrylate, (meth) acrylamide, (meth) diacrylamide, N, N-dialkylaminoalkyl (meth) acrylate, phosphonooxyethyl (meth) Phosphate group-containing (meth) acrylate such as acrylate, vinyl acetate,
There are compounds such as α-olefins such as hexafluoropropylene and tetrafluoroethylene, and perfluorovinyl ethers such as trifluoromethyltrifluorovinyl ether.

Further, 2-hydroxyethyl (meth) acrylate and polyoxyalkylene glycol (meth)
(Meth) acrylates such as acrylate, 3-hydroxypropyl (meth) acrylate, 2,3-dihydroxypropyl (meth) acrylate, vinyl ethers such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether, and allyl compounds such as hydroxyethyl allyl ether , 1 to these with ε-caprolactone
Compound obtained by adding 6 mol, compound obtained by reacting monofunctional epoxy compound with carboxylic acid-containing monomer such as (meth) acrylic acid, and fatty acid with epoxy group-containing monomer such as glycidyl (meth) acrylate Alternatively, a hydroxyl group-containing monomer such as a compound obtained by reacting a hydroxy acid can be used.

The number average molecular weight of the acrylic copolymer obtained by copolymerizing the silanol group-containing monomer with the copolymerizable monomer is within the range of 800 to 2500, and 900 to 1200. The range of is preferable. If the number average molecular weight is less than 800, crosslinking of the resin will be insufficient and the chemical resistance of the coating will be poor. If it exceeds 2500, the molecular weight of the resin will be high and the viscosity of the coating will increase. This is because the effect of reducing the solvent decreases.

The ratio of the weight molecular weight to the number average molecular weight of the acrylic copolymer is suitably 2.5 or less, preferably 2 or less. This is because when the ratio is 2.5 or more, molecules having a remarkably high molecular weight are present in the resin, the viscosity of the coating material is increased, and the effect of reducing the solvent cannot be expected.

When the curing agent is a melamine resin, a phosphoric acid ester or dodecylbenzene is used as a curing catalyst for reacting the first component made of the above polyester polymer with the curing agent as the second component. Examples thereof include organic acids such as sulfonic acid and p-toluenesulfonic acid, and amine acids thereof.

Examples of the curing catalyst used when the curing agent is an isocyanate prepolymer include organic tin compounds such as dibutyl susdilaurate, dibutyl tin malate and the like, in addition to the above organic acids. When the curing agent is a silanol group-containing oligomer, an organic acid or a tin compound such as dibutyltin laurate is used as a curing catalyst. When the oligomer containing the acid anhydride is used as the curing catalyst, it is not necessary to use the curing catalyst.

Further, when the above-mentioned first component and second component are reacted to form a coating material, various resins, solvents and coloring agents such as pigments or dyes, other than the above, other flow regulators and UV absorbing agents are used. Needless to say, various conventionally known additives such as agents, light stabilizers, and silane coupling agents are added as necessary.

[0030]

According to the high solids coating composition having the above structure,
By reacting a trifunctional or higher functional hydroxyl group possessed by a compound having a molecular weight of 200 or less constituting the component with a curing agent constituting the second component, the resin of the first component is sufficiently cross-linked to obtain proper hardness. Will be done. Further, since the resin (first component) constituting the paint has a relatively small molecular weight, the amount of solvent in the paint is reduced.

[0031]

EXAMPLES Next, examples of the present invention will be described in comparison with comparative examples. In the following, all parts and% are based on weight unless otherwise specified.

(1) Synthesis of Polyester Oligomer (First Component) First, 2 weight of butyl acetate was used as a solvent in a four-necked flask equipped with a stirrer, an inert gas inlet, a thermometer and a cooler.
By adding 00 parts, 63.1 parts of glycerin as the compound (a), and 222 parts of methylhexahydrophthalic anhydride as the compound (b), the temperature was raised to 130 ° C. and the reaction was performed for about 2 hours to give the compound (C) is synthesized. Then, 514.9 parts of "CURJURA E10" trade name of Showa Shell Sekiyu KK as a monofunctional epoxy compound (d) and 2 parts of dimethylimidazole were added, and the mixture was further reacted for 2 hours under reduced pressure. The resin (molecular weight 1166) made of the polyester oligomer according to Example 1 is synthesized by removing the resin.

Similarly, by mixing the respective components in the composition ratios shown in Table 1 below, the resins according to Examples 2 to 5 having a molecular weight of 2000 or less are synthesized. Especially Example 2
And in the case of Example 4, the molecular weight of the polyester oligomer was 1000 or less. Furthermore, by mixing the respective components in the composition ratio shown in Table 1 below, a molecular weight of 200 was obtained.
0 or more of the resins according to Comparative Examples 1 to 3 were synthesized.

[0034]

[Table 1]

(2) Synthesis of Curing Agent Reacting with Hydroxyl Group 20 parts of xylene and 10 parts of butyl isoacetate were placed in the above-mentioned four-necked flask and stirred at 130 ° C. to give styrene 2
3.7 parts, 16.4 parts of γ-acryloxypropyltrimethoxysilane, 30 parts of butyl acrylate, 0.3 parts of trade name "Perbutyl A" of NOF CORPORATION, and 0.1 parts of "Perbutyl O". The mixed solution with 1 part is added dropwise over 3 hours. Then, after holding for 1 hour, 0.1 part of the above-mentioned "perbutyl O" was further added and held for 3 hours to synthesize the curing agent of the first component according to Example 6.

(3) Preparation of Base Coat Resin 20 parts of xylene and 10 parts of butyl isoacetate were placed in the four-necked flask and stirred at 130 ° C., and 20 parts of butyl acrylate and 10 parts of 2-hydroxyl ethyl methacrylate were added. Parts, 20 parts of methyl methacrylate, 10 parts of butyl methacrylate, 0.05 parts of trade name "Perbutyl O" of NOF CORPORATION, and 0.05 parts of "Perbutyl A", and a monomer mixture of 0.05 parts of the same over 3 hours. Let it drip. Then, after completion of dropping, the mixture is stirred for 1 hour, 0.05 part of trade name "Perbutyl A" manufactured by NOF CORPORATION is added, and after stirring for 2 hours, 10 parts of xylene is added to obtain a resin solution having a solid content of 60%.

(4) Preparation of base coat 50 parts of the base coat resin obtained as described above, and 5 parts of Asahi Kasei's trade name "Aluminum paste CR601S"
Mitsui Toatsu Chemicals Inc. product name "Uban 122" 21.5 parts, xylene 15 parts, butyl acetate 15 parts, Big Chemie product name "BYK307" 0.5 parts, Eastman product name " A base coat is prepared by mixing and stirring 5 parts of CAB531-1 "and 20 parts of toluene.

(5) Preparation of clear paint The resins according to Examples 1 to 5 and Comparative Examples 1 to 3 described above, the curing agent according to Example 6 and a predetermined curing compounded as shown in Table 2 below. Clear coatings A to K were prepared by a conventional method using an agent, a curing catalyst and a solvent. In addition, in Table 2, Sumidur N3500 is a trade name of a curing agent according to Sumitomo Bayer Urethane Co., Ltd.

[0039]

[Table 2]

(6) Preparation of coated plate Xylene 50 was applied to the plate coated with electrodeposition and intermediate coating.
Parts of the above base coat diluted with FC (Ford Cup) # 4 for 12 seconds in a mixed solvent of 50 parts and 50 parts of butyl acetate. After leaving for 10 minutes, the clear coatings A to K were mixed with xylene-sixahexynone (weight ratio = 60 /
FC (Ford Cup) #
The viscosity was adjusted to 4 seconds at 18 seconds, the solution was applied to the plate, left for 10 minutes, and then dried at a temperature of 140 ° C. for 15 minutes.

(7) Comparison and Evaluation The coated plate on which the clear coating film of finishes A to K was formed as described above was fixed to the ceiling of an automobile, and car washing was repeated by a car washing machine. Then, the scratches formed on the coating film by rubbing the car wash brush were visually observed, and the scratch resistance was evaluated according to the state of the scratches.
The evaluation results shown in were obtained. The number of car washes was 20 each.

When the application solids were measured in the state where the viscosity of the coating materials A to K was adjusted, the results shown in Table 3 were obtained. This application solid is measured at 20 ° C for each of the above paints A to K.
FC at room temperature and under heating at 60 ° C
(Ford Cup) # 4 by examining the percent solids in the paint when diluted to 18 seconds.

[0043]

[Table 3]

As can be seen from Table 3, Examples 1 to 1 above
In the coatings A to F according to the present invention using the resin composed of the polyester oligomer shown in 5, almost no scratches were generated, whereas in the coatings G to K using the resins according to Comparative Examples 1 to 3. Occurrence of scratches was observed. Further, in the case of the coating materials A to F according to the present invention,
It can be seen that the application solid in the paint is 65 to 90, and the amount of solvent is small. On the other hand, in the case of the coating materials G to K using the resins according to Comparative Examples 1 to 3, the application solid content in the coating material is 43 to 6
It was 1 and it was confirmed that the amount of solvent was relatively large.

In particular, in the case of the coatings B, D and G using the coating compositions of Examples 2 and 4 in which the number average molecular weight of the first component consisting of polyester oligomer is 1000 or less, the application solid is 79 or more. It was confirmed that the amount of solvent was extremely small.

As the comparative example, the one very close to the example is adopted, but if the same evaluation test is performed using a usual high solids coating composition far from the example, It is considered that very conspicuous scratches are generated and the amount of the solvent is larger than that of the above-mentioned comparative example.

As described above, the high-solids coating composition according to this example can increase the scratch resistance of the coating and effectively improve the durability of the coating film, and reduce the viscosity of the coating. It can be seen that the paint has a very excellent property as a paint capable of reducing the amount of the solvent without causing it.

[0048]

As described above, the high solids coating composition of the present invention has a molecular weight of 200 or more having a trifunctional or higher functional hydroxyl group.
A compound obtained by reacting the following compound with a compound of an acid anhydride is reacted with a monofunctional epoxy compound to obtain a first component consisting of a polyester oligomer having a number average molecular weight of 2000 or less, and a reactivity with a hydroxyl group. Since it is formed as an indispensable component with the second component consisting of the curing agent that it has, it effectively reduces the molecular weight of the resin that constitutes the paint without lowering the properties such as fluidity and scratch resistance of the paint. be able to.

Therefore, the amount of the solvent in the paint can be remarkably reduced as compared with the conventional paint, and the generation of air pollution due to the evaporation of the solvent at the time of coating can be surely prevented, and at the same time as the conventional paint. When the same amount of coating material is applied, there is an advantage that the thickness of the coating film can be made thicker than before.

Claims (1)

[Claims] 1. A high-solids coating composition comprising the following first and second components as essential components. First component: a polyester having a number average molecular weight of 2000 or less obtained by reacting a compound obtained by reacting a compound having a trifunctional or higher functional hydroxyl group with a molecular weight of 200 or less with a compound of an acid anhydride with a monofunctional epoxy compound. Oligomer Second component: Hardener having reactivity with hydroxyl group