JPS6187769A - Powder coating composition - Google Patents

Abstract

PURPOSE:To provide a powder coating compsn. which gives a coating film having excellent pigment inclusion power and good appearance (smoothness, brilliancy, etc.), by using an amine compd.-modified glycidyl group-contg. vinyl copolymer as a resin component. CONSTITUTION:A prim. or sec. amine contg. a tert. amino group (e.g. a reaction product between abietic acid and N,N-dimethylpropylamine) is used. 0.01-1pt.wt. said amine compd. is reacted with 100pts.wt. copolymer having a glass transition temp. of 10-75 deg.C and a number-average MW of 1,500-30,000, composed of 5-40wt% glycidyl group-contg. monomer (e.g. glycidyl acrylate) and 95-60wt$ ethylenically unsaturated monomer (methyl methacrylate or styrene) to obtain a modified resin. Said modified resin, a dibasic carboxylic acid (e.g. 1,12- dodecanedioic acid) as a hardener, a pigment and other additives are melt-mixed and the mixture is cooled and crushed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermosetting powder coating composition that provides a coating film with a well-defined finished appearance such as smoothness and sharpness.

(Prior art and its problems) Powder coatings, which have been developed as low-pollution coatings in recent years, are used in a wide range of fields. However, the paint films obtained from powder coatings that do not use solvents tend to have poorer finished appearance such as smoothness than conventional solvent-based coatings, and it is not possible to increase the pigment concentration, resulting in hidden problems. However, there is a need for the development of a powder coating with an excellent finished appearance since it lacks the disadvantage of low strength.

The inventors of the present invention have conducted intensive research to solve this problem.
As a result, by modifying the conventional vinyl resin for powder coatings with a specific amine compound, the finish appearance such as the smoothness and sharpness of the powder coating film was significantly improved, and the pigment concentration was increased to a maximum of 25%. The present invention was achieved by discovering that it is possible to further increase the amount, which was limited to about % by weight.

That is, the present invention is produced by copolymerizing 5 to 40% by weight of a glycidyl group-containing monomer and 95 to 60% by weight of an ethylenically unsaturated monomer, and has a glass transition temperature in the range of 10 to 75°C and 1.
A vinyl copolymer having a number average molecular weight in the range of 500 to 30,000 and containing 100 parts by weight of tertiary amine! A powder coating composition comprising a vinyl copolymer modified with 0.01 to 1.0 parts by weight of a primary or secondary amine compound and a dibasic carboxylic acid.

In the present invention, as the vinyl copolymer before being modified with the amine compound, those produced by any known method can be adopted, but among them, those produced by solution polymerization are used, and the vinyl copolymer is produced in a solution state or After removing the solvent, the amine compound was added in the molten state and uniformly dispersed at 80°C.
Preferably, those obtained by heating at a temperature of ~180° C. for 0.1 to 5 hours and reacting with glycidyl groups.

The above amine compound is a primary or secondary amine containing a 6th class amine and has the general formula (wherein R+ represents an alkyl group 7 and R2 represents an alkyl group or a hydrogen atom). It is used after being modified by forming a salt with a special carboxylic acid compound or reacting with an epoxy group-containing compound that does not have unsaturated bonds so as to minimize the amount of unsaturated bonds.

Examples of the amine represented by the above general formula include N, N
dimethylmethylamine, N,N dimethylethylamine,
N, N dimethylfurobylamine, N, N diethylmethylamine, N, N diethyl ethylamine, N, N
Examples include diethylpropylamine, N,N dinotyl/N'methylpropylamine, and the like.

Further, as the special carboxylic acid, diterpene acids are preferable, such as abietic acid, pimaric acid, neoabietic acid,
levopimaric acid, in-d-pimaric acid, photocarbic acid,
Agatene dicarbonate, rubenic acid, etc.? Among them, abietic acid and pimaric acid are the most common.

Furthermore, examples of the epoxy group-containing compound include phenyl glycidyl ether, allyl glycidyl ether, and epoxidized soybean oil.

The amount of the amine compound is 0 per 100 parts by weight of the vinyl copolymer.
．． It is preferable to add 01 to 1.0 parts by weight for modification. If it is less than 0.01 part by weight, there will be no effect of improving the finished appearance of the coating film, such as smoothness and sharpness, and if it is more than 1.0 part by weight, weather resistance will deteriorate, which is undesirable.

A still more preferable range is 0.05 to 0.5 parts by weight.

Using the above-mentioned vinyl copolymer according to the present invention, a powder coating can be produced by blending with dibasic carboxylic acid, a pigment, a curing catalyst, a flow regulator, etc. used in the production of powder coatings.

When the content of the glycidyl group-containing monomer component of the vinyl copolymer is less than 5% by weight of the total monomers, the coating strength and metal adhesion decrease; This is unsuitable because the smoothness of the painted surface decreases due to the curing reaction.

If the glass transition temperature of the vinyl copolymer is less than 10°C, the storage stability of the powder coating will decrease, and if it exceeds 75°C, the thermal fluidity will decrease and the smoothness of the painted surface will be impaired, making it unsuitable. Furthermore, if the number average molecular weight of the vinyl copolymer is less than 1,500, the strength, chemical resistance, and storage stability of the paint film will decrease, while if it exceeds 1,000, the smoothness of the painted surface will decrease. Therefore, it is not desirable.

Examples of glycidyl group-containing monomers used to provide g)nosidyl groups in the vinyl copolymer of the present invention include glycidyl acrylate, β-methylglycidyl acrylate, glycidyl methacrylate, and β-methylglycidyl acrylate. Seven examples include glycidyl ester of meth)acrylic acid, (methyl)IJ cidyl ether of allyl alcohol, (methyl)glycidyl ether of methallyl alcohol, N-glycidyl acrylic acid amide, and glycidyl vinylsulfonate. These can be used alone or as a mixture of two or more.

On the other hand, the copolymerizable monomer is an ethylenically unsaturated monomer with low reactivity with glycidyl groups,
and radically co-M with the above glycidyl group-containing monomer.
← monomers are used, for example, acrylic esters,
Examples include methacrylic acid esters and other ethylenically unsaturated monomers. These may be used alone or as a mixture.

Examples of esters of acrylic or methacrylic acid include methyl acrylate, ethyl acrylate, n-propyl acrylate, inpropyl acrylate, mn-butyl acrylate, ibutyl acrylate, and t-acrylate.
ert-butyl, cyclohexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, 2-ethyloctyl acrylate, dodecyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, n-provir methacrylate, methacrylate Inflovir acid, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, methacrylic q2-
Ethylhexyl, octyl methacrylate, 2-ethyloctyl methacrylate, benzyl methacrylate, dodecyl methacrylate, phenyl methacrylate, 2-ethyl acrylate
Hydroxyethyl, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-methacrylate
Examples include hydroxyl group-containing (meth)acrylic esters such as -hydroxypropyl.

In addition, other ethylenically unsaturated monomers include fumaric acid dialkyl ester, itaconic acid dialkyl ester, styrene, vinyltoluene, α-methylstyrene, acrylonitrile, metacyclonitrile, acrylonitrile, metacyclonitrile, and acrylonitrile. Examples include amides such as rylamide, methacrylamide, methylolacrylamide, alkoxymethylolamide, vinyloxazoline, vinyl acetate, vinyl propionate, lauryl vinyl ether, parogen-containing vinyl monomers, silicon-containing vinyl monomers, and the like.

On the other hand, as the dibasic carboxylic acid used as a curing agent, an aliphatic or aromatic dibasic carboxylic acid is used. For example, glutaric acid, adipic acid, pimelic acid, superric acid, azelaic acid, 7N cy/acid, 1,12-dodecanedioic acid, 1,2o-icosanedioic acid, 1,24-tetraeicosanedioic acid, maleic acid, Examples include di-groups such as citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, hexahydrophthalic acid, and cyclohexene 1,2 dicarboxylic acid. Also, succinic anhydride, sebacic anhydride, phthalic anhydride, It may also be a dibasic carboxylic acid anhydride such as itaconic anhydride.

Among these, 1,12 dodecanedioic acid and 1,20-icosasic acid are preferred because they have a good balance of performance. Their usage ratio can be arbitrarily combined, but the equivalent ratio of the epoxy group to the carboxyl group in the dibasic acid is 0.5 to 1,
It is preferable to use the ratio in a range of 5.

The powder coating composition of the present invention includes synthetic resins such as epoxy, polyester, and polyamide, various resins such as cellulose derivatives, pigments, flow regulators, antiblocking agents,
Additives for commonly used paints such as ultraviolet absorbers, benzoin, antistatic agents, antioxidants, etc. One or more types can be added as needed, and powders can be used with or without additives. Practical as body paint.

Any well-known method can be used to produce powder coatings, but usually after mixing the above components, it is heated to 80 to 1
The methods used include sufficiently melting and mixing at about 20°C, cooling, and then pulverizing to form a powder coating. Regarding the coating method, the object to be coated is coated by a well-known coating method such as electrostatic spraying or fluidized dipping, and then baked in a baking oven at a temperature of 7150 to 210°C to obtain a powder coating film. I can do it.

(Example) (1) Production of vinyl copolymer Production of special amine compound (1) In a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen inlet, 50 parts of xylene, abietic acid, and 1S7 ．．
After heating in a nitrogen atmosphere, 13.7 parts of N,N-dimethylpropylamine was gradually added at a temperature of 60 to 80'C, and the mixture was heated and reacted for 2 hours. This material is used as a special amine compound hole (solid content 50%).

A similar substance is Disparon 873-N (K, manufactured by Kusumoto Kasei Kogyo).

(11) Add 500 parts of xylene and 480 parts of phenyl glycidyl ether into a reactor equipped with a thermometer, stirrer, reflux condenser, and nitrogen inlet, and add 100 to 11 parts of phenyl glycidyl ether in a nitrogen atmosphere.
Heat to 0°C. 20 parts of N,N-dimethylpropylamine were gradually added thereto, and the mixture was allowed to react for 6 hours. This thing! Special amine compound "J3)" (solid content 50%).

(Production of Bl vinyl copolymer) 667 parts of xylene is added to a reactor equipped with a thermometer, a stirrer, a reflux condenser, and a nitrogen introduction lower, the air inside the reactor is replaced with nitrogen, and the mixture is heated to reflux.

A mixture consisting of monomers and a polymerization initiator in the amounts shown in Table 1 was added thereto for 4 hours, and the mixture was further kept under reflux for 1 hour, cooled, and azobisisobutyronitrile 0.
After adding 5 parts, the remaining monomer is polymerized at 80 to 100°C to complete the polymerization.

The amount of amine compound shown in Table 1 was added to the above polymerization solution, and 1
Heat the reaction at 00°C for 1 hour. A solid vinyl copolymer 7 was obtained by removing the solvent from the obtained polymerization solution.

Table 1 Note) The glass transition temperature is the value measured from the temperature change in specific volume using a platometer.

Rice is converted into solid content (2) Production of powder coating The solid vinyl copolymers (a) to (el) produced as described above (see Table 2) were dibasic carboxylic acid in the amount shown in experiment numbers (1) to (5),
The mixture was melt-kneaded together with the pigment and fluidity modifier, cooled, crushed in a crusher, and passed through a 150-mesh sieve.

As comparative examples, experiment numbers (6) to a1 were produced in the same manner except that the amounts of substances shown in Table 2 were used.In the table, the product name is Remix LFiSBS Chemical Co., Ltd.

(3) Evaluation of powder coating Each of the powder coatings with experiment numbers <1) to αQ shown in the second element was treated with zinc phosphate using an electrostatic spray coating machine for powder coatings according to the respective experiment numbers. 0.0, 8-J-thick matte steel plate was coated with a film thickness shown in Table 3, and heated at 180℃ x 3
A test plate was obtained by baking for 0 minutes, and the cured coating film was evaluated for each item shown in Table 5 according to each experiment number.
The results are shown in Table 3.

The clarity of the paint film is determined by the gloss of the painted surface! The smoothness of the coating film was visually judged as specified in JISK-54006.1, and the weather resistance was evaluated by accelerated testing using Q, U, and V testers.

(Effect of the invention) The water side (1) to (3) of the present invention have the same copolymer composition, but the amount of the amine compound used for modification varies from 0.01 to 1.0 parts by weight, and the water side C4) ( 5) shows the test results when the copolymer composition was changed and the amount of the amine compound was varied, and the pigment concentration was 60%. In either case, the finished appearance is excellent and there is no deterioration in physical properties such as weather resistance.

The comparative examples are all monocopolymer compositions used in (1) to (3), and the comparative example (6) has limited conditions such that the amount of amine compound used for modification is o, o o s parts by weight. This is an example of a pigment concentration of 25% when modified with a smaller amount, and comparative example (9) is an example of a pigment concentration of 30%.
If the amount is small like this, improve the smoothness of the powder coating surface,
There is no effect of increasing pigment concentration.

Comparative Examples (7) (8? αQ is an example where the amount of amine compound used for modification is larger than the limiting conditions, and both have poor weather resistance.

The above examples show that if the amount of the amine compound used for modification is within the specified conditions, physical properties such as weather resistance can be improved (finished appearance can be improved and pigment a degree can be improved). There is.

Claims (1)

[Claims] 10 to 40% by weight of a glycidyl group-containing monomer and 95 to 60% by weight of an ethylenically unsaturated monomer.
Glass transition temperature in the range of 75℃ and 1500-30000
Vinyl copolymer 100 having a number average molecular weight in the range of
Powder comprising a vinyl copolymer modified with 0.01 to 1.0 parts by weight of a primary or secondary amine compound containing a tertiary amine and a dibasic carboxylic acid. Paint composition.