JPS5812309B2 - Funtai Triyou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder coating that produces less smoke during baking, has a good coated surface, and can form a coating film with excellent physical and chemical strength.

The advantage of powder coatings is that they do not use solvents, but because of this, problems that are not considered problems with solution-based coatings or that can be easily improved become difficult problems, so various performances of the coating film are difficult to solve. In addition, it is not easy to balance the storage stability of powder coatings. In view of these points, the present inventors have conducted extensive research and found that by modifying a polymer containing a carbamate group with polyester, It was discovered that the smoothness, gloss, mechanical strength, solvent resistance, weather resistance, salt resistance of the coating film, and storage stability of the powder coating can be improved, leading to the present invention.

That is, the present invention provides a powder whose film-forming component is a resin obtained by polymerizing a carbamate group-containing vinyl monomer and other vinyl monomers (hereinafter referred to as carbamate resin) in the presence of a polymerizable unsaturated polyester. It concerns body paint.

To explain in detail the performance of the paint of the present invention, since the carbamate resin contains a polyester skeleton,
Since it acts as an internal flow agent, the coated surface becomes smoother, and weather resistance and salt resistance are also improved.

In addition, the curing mechanism of carbamate resin is based on a self-curing reaction between carbamate groups and hydroxyl groups, but this reaction does not occur at temperatures such as kneading, and on the other hand, at baking temperatures of 150C or higher, it fully reacts and cures, so the painted surface condition You can obtain excellent results.

These excellent effects are only exhibited when the carbamate group-containing vinyl monomer and polyester are copolymerized, and the powder coating film obtained from the blend of the carbamate group-containing polymer and polyester is , it was significantly inferior in terms of smoothness, gloss, and mechanical strength.

Examples of the carbamate group-containing monomer that is the first component of the carbamate resin used in the present invention include N-alkenyl alkyl carbamates, N-alkenyl capsulactam carbamates, N-alkenyl allyl carbamates, and N-aralkyl carbamates. Included are nyl alkyl carbamates, N-aralkenyl allyl carbamates, N-(meth)acryloxyalkylene alkyl carbamates, N-styrylalkyl carbamates and their thiocarbamates.

The alkyl group of these carbamate group-containing monomers preferably has 8 or less carbon atoms.

One or more of the above-mentioned carbamate group-containing monomers are used in an amount of 5 to 50% by weight (all percentages hereinafter indicate weight%) of the total raw materials, preferably 10 to 30%.

If the amount used is less than 5%, the physical properties of the coating film will be poor;
Exceeding this is not preferable as the flexibility will be poor.

The polymerizable unsaturated polyester as the second component can be obtained usually by a method of causing a condensation or addition reaction of an unsaturated group-containing component, an acid component, and an alcohol component.

Among the raw materials, unsaturated group-containing components include, for example, fumaric acid, maleic acid (anhydride), itaconic acid, etc., and acid components include, for example, o. m. p-monophthalic acid, its lower alkyl esters, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, benzoic acid, etc. Alcohol components include glycerin, ethylene glycol, propylene glycol, neopentyl glycol, pentaerythritol, etc. , trimethylolpropane, trimethylolethane, etc.

The preferred ratio (weight ratio) of the unsaturated group-containing component and the unsaturated group-free component to be used is 0.1:100 to 10:10.
0, more preferably 0.5:100 to 5:100.

If the amount of the unsaturated group-containing component is too small, the effect of the present invention will be small, and if it is too large, it will tend to gel or the molecular weight of the carbamate resin will become high, resulting in poor coating film smoothness.

The hydroxyl value of polymerizable unsaturated polyester is 20-300K
OHmg/g (units will be omitted hereafter), acid value is 20K
It is OHmg/g (units are omitted below) or less, more preferably 10 or less.

If the acid value exceeds 20, dissociation of the carbamate group will be delayed, which is not preferable.

Furthermore, if the hydroxyl value is less than 20, the physical properties of the coating film will be poor;
If it exceeds 00, the chemical resistance will be poor, which is not preferable.

The appropriate amount of polymerizable unsaturated polyester used is 5 to 70%.

The preferred ratio of the carbamate group-containing monomer to the carbamate group-containing monomer is 1:5 to 5:
1, more preferably in the range of 1:3 to 3:1.

Other vinyl monomers as the third component include (meth)acrylic acid esters such as methyl (meth)acrylate and butyl (meth)acrylate, styrene, vinyltoluene, acrylonitrile, vinyl acetate, vinyl chloride, Diesters of unsaturated dibasic acids such as dibutyl fumarate and dimethyl itaconate, (meth)acrylic acid, β
-Hydroxyethyl (meth)acrylate, (meth)acrylamide, etc.

The appropriate amount of these vinyl monomers to be used is in the range of 25-90%.

Among these monomers, monomers having functional groups reactive with carbamate groups, such as hydroxyl groups, carboxyl groups, and amide groups, inhibit the reaction between carbamate groups and the hydroxyl groups of polyester, so the amount used is limited. It is necessary that
The amount used is preferably 20% or less.

The carbamate resin used in the present invention can be obtained by a well-known method such as solution polymerization of each of the above components, followed by solvent removal, bulk polymerization or suspension polymerization, and then collection of granular resin.

Its preferable number average molecular weight is 3.000 to 30.000
, more preferably 5,000 to 15,000, and a preferable ring and ball softening point is 80 to 150°C, more preferably 90 to 120°C.

A blocked isocyanate dissociation catalyst can be added to promote the self-curing reaction of the carbamate resin used in the present invention.

These include, for example, organic metal salts, organic tin compounds, and tertiary and quaternary amines, the preferred amount of which is in the range of 0.01 to 10% based on the carbamate resin.

In addition, in order to improve the smoothness of the painted surface, acrylic acid long chain alkyl ester polymers with a softening point of 50°C or less, fluorinated polymers,
Cellulose nacetate butyrate, etc. can be added.

It goes without saying that other resins can be added to improve coating film performance.

For example, by adding epoxy resin, the gloss and smoothness of the coating film can be improved.
Salt resistance etc. can be improved.

Particularly in the case of epoxy resins, it consumes the carboxyl groups in the carbamate resin that retard the dissociation reaction of the bamate groups and lowers the acid value of the system during curing, so it is a preferred additive to speed up the dissociation reaction. I can say it.

Powder coatings can be prepared by any known method.

The resulting powder coating can be applied by any known method such as an electrostatic slurry method or a fluidized dipping method.

The present invention will be explained below according to examples.

"Parts" in the text indicate parts by weight.

Production of polyester A 586 parts of isophthalic acid, 1.6-\xanediol 10
1 part of trimethylolpropane, 208 parts of neopentyl glycol, and 20 parts of maleic anhydride were heated at 1180°C for 2 hours with stirring in an inert gas stream, then 2 hours.
Heated at 00℃ for about 7 hours to achieve a softening point of 85C1 and a hydroxyl value of 12.
5. Polyester A having an acid value of 4.2 was obtained.

Production of Polyester B 750 parts of dimethyl terephthalate, 100 parts of adipic acid, 180 parts of trimethylolpropane, 450 parts of neopentyl glycol, 21 parts of maleic anhydride, and 0 parts of zinc acetate.
．． 5 parts were charged into a reactor, and the temperature was raised from 150°C to 210°C in 7 hours while removing the generated methanol from the system, and then maintained at 210°C at 2 mrHg for 2 hours to reach a softening point of 95°C.
Polyester B having a hydroxyl value of 125 and an acid value of 1.5 was obtained.

Example 1 To a mixture of 200 parts of water and 3 parts of triammonium phosphate heated to 50°C, 2 parts of calcium acetate and 0.5 parts of sodium sulfite were added while stirring, and then the mixture was heated to 60°C and heated in a nitrogen stream. 30 parts of styrene, 15 parts of N-vinyl isopropyl carbamate, 30 parts of polyester A, 25 parts of isobutyl methacrylate, 4 parts of Abbis isobutyronitrile,
1 part of tert-butyl perpenzoate and 1 part of n-lauryl mercabutane were added, and the mixture was kept at the same temperature for 3 hours, then gradually raised to 80°C, and then kept at the same temperature for 15 hours before separating the product. Washed with water and dried to a softening point of 105°C.
A resin with a molecular weight of 8000 was obtained.

100 parts of the above resin, 0.5 parts of Modaflow (flow control agent manufactured by Monsan Di), 1 part of dibutyltin dichloride, and 50 parts of titanium oxide were kneaded at 100°C for 3 minutes using a heated triple roll, and then cooled and solidified. The mixture was separated using a mesh wire gauze to obtain a powder coating with a size of 150 mesh or less.

This powder coating was applied to a mild steel plate by electrostatic spray coating, and
A coating film was obtained by baking at 0° C. for 20 minutes.

Example 2 95 parts of the polymer of Example 1, 5 parts of Evicron 1050 (an epoxy resin manufactured by Inu Nippon Ink Chemical Industry Co., Ltd.), 0.5 parts of Modaflow, 0.5 parts of dibutyltin dichloride, and 50 parts of titanium oxide. A baked coating film was obtained by baking in the same manner as in Example 1.

Example 3 35 parts of methyl methacrylate, 15 parts of inbutenyl methyl carbamate, 30 parts of polyester B, and 20 parts of inbutyl methacrylate were polymerized in the same manner as in Example 1 to obtain a resin having a softening point of 110° C1 and a molecular weight of 8900.

Baking was carried out in the same manner as in Example 1 using 100 parts of the above resin, 0.5 part of Modaflow, 1 part of dibutyltin acetate, and 50 parts of titanium oxide.

Comparative Example 1 Using 30 parts of styrene, 15 parts of β-hydroxyethyl methacrylate, 15 parts of N-vinylbutyl carbamate, 35 parts of inbutyl methacrylate, and 5 parts of 2-ethylhexyl acrylate, the softening point was determined in the same manner as in Example 1. 11
A resin having a molecular weight of 9000 was obtained at 5°C.

Example 1 Using 100 parts of this resin, 0.5 part of Modaflow, 1 part of dibutyltin dichloride and 50 parts of titanium oxide,
Baked in the same way.

Comparative Example 2 Using 30 parts of styrene, 20 parts of N-vinylbutyl carbamate, and 50 parts of inbutyl methacrylate, Example 1
A resin having a softening point of 108° C. and a molecular weight of 8,000 was obtained in the same manner as above.

Using 70 parts of this resin, 30 parts of polyester A, 1 part of dibutyltin dichloride and 50 parts of titanium oxide, Example 1
Baked in the same way.

Table 1 shows the performance of the baked coating films obtained in each of the above examples.

Note) Salt water resistance indicates the peeling width of the coated surface when the sample was cut and sprayed with salt water for 500 hours, then cellophane tape was attached and removed.

Claims (1)

[Claims] 1 Hydroxyl value 20-300KOHmg/? , acid value 20K
Polymerizable unsaturated polyester with OHm9/g or less 5-70
Carbamate group-containing vinyl monomer in the presence of 5% by weight
A powder coating whose film-forming component is a resin obtained by polymerizing ~50% by weight and 25-90% by weight of other vinyl monomers.