JPH01282271A - Resin composition for powder coatings - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of providing a coating film excellent in film hardness, stain and weather resistance, mechanical properties, etc., by mixing a specified polyester resin with a copolymer containing glycidyl groups, a block isocyanate and an aliphatic dibasic acid. CONSTITUTION:(A) A polyester resin with 5-100, preferably 8-25mg KOH/g acid value, 5-100, preferably 10-25mg KOH/g hydroxyl value, 80-150 deg.C softening point and 1000-10000, preferably 2000-5000 number-average molecular weight is mixed with (B) a copolymer with 300-8000, preferably 500-6000 number-average molecular weight obtained by copolymerization between 10-95wt.%, preferably 20-60wt.% vinyl monomer selected from a group consisting of glycidyl (meth)acrylate and beta-methylglycidyl (meth)acrylate, 0-60wt.%, preferably 0-20wt.% vinyl monomer containing a hydroxyl group and 5-90wt.%, preferably 40-80wt.% another vinyl monomer, (C) a block isocyanate and (D) an aliphatic dibasic acid to provide the objective composition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a new and useful resin composition for powder machinery, and more specifically to a specific polyester resin, a copolymer having a glycidyl group, a block The present invention relates to a resin composition for powder coatings that is composed of an isocyanate and an aliphatic dibasic acid and has particularly excellent coating film hardness, stain resistance, mechanical properties, etc.

[Prior art]

Currently, thermosetting powder coatings include combinations of carboxyl group-containing ester resins and polyepoxy resins, hydroxyl group-containing polyester resins and block incyanates, and acrylic polyepoxy resins and aliphatic dibasic acids. Widely used. However, which tie 7'
However, in order to maintain mechanical properties, the coating film hardness was lower than that of solvent-based thermosetting paints. It has also been proposed to use block isocyanate in combination with a terester resin having both carboxyl groups and hydroxyl groups and an acrylic polyepoxy resin to perform composite crosslinking.
In order to obtain high hardness, the molecular weight of the polyester resin had to be lowered, so a decrease in mechanical properties was unavoidable.

[Problem to be solved by the invention]

The present inventors conducted intensive research in view of the existence of such drawbacks in the conventional technology, and as a result, the present inventors found that the present invention has both a carboxyl group and a hydroxyl group. (By newly blending an aliphatic dibasic acid into a resin composition consisting of a polyester resin, a copolymer having a glycidyl group, and a block isocyanate), the excellent properties of such a resin composition are not impaired in any way. However, the inventors discovered that the above-mentioned drawbacks could be solved, and completed the present invention.

[Structure of the invention]

To summarize the present invention, the present invention includes, as essential components, an acid value of 5 to 100 rn9r<oH/11 (hereinafter, only numbers will be described without units), and a hydroxyl value of 5 to 100.
100 to KOV'Il (same as above) and a softening point of 80 to 15
At 0°C, and number average molecular weight (hereinafter abbreviated as Mn).
1,000 to 10,000, (B) glycidyl acrylate (GA), glycidyl methacrylate (GMA), β-methylglycidyl acrylate (MGA), and β-methylglycidyl methacrylate) (MGMA) One or more vinyl monomers selected from the group 10 to 95 polymers,
A copolymer with an Mn of 300 to s, ooo obtained from 0 to 60% by weight of a hydroxyl group-containing vinyl monomer and 5 to 90% by weight of other vinyl monomers, (C) a blocked isocyanate, and (D) an aliphatic dibasic acid. A resin composition for powder coating comprising:

Hereinafter, the configuration of the present invention will be explained in detail.

First, the constituent components will be explained.

(4) Regarding the component; The polyester resin as the above-described component has an acid value of 5 to 100. Preferably 8 to 50, more preferably 8 to 25, and the hydroxyl value is 5 to 100, preferably 1
0 to 50, more preferably lO to 25, and a softening point of 80
~150°C, preferably 100-130°C, and Mn
is 1,000 to 10,000, preferably 2,000 to
5,000, but as long as it falls within this range, it may have a branch structure or a linear structure.

There is no particular restriction on the method for preparing the 4-reester resin, and any well-known and commonly used method can be applied as is.
Both well-known and commonly used dibasic acids, tribasic acids or higher polybasic acid components, and dihydric alcohols and trihydric alcohols or higher polyhydric alcohol components can be used.

Therefore, only representative acid components and alcohol components constituting the I-reester resin matrix of the present invention will be listed. ,
trimellitic acid, pyromellitic acid and their anhydrides; or adipic acid, sepacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, methylhexahydrophthalic acid and On the other hand, alcohol components include ethylene glycol, propylene glycol, 1,3-butaneol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, bishydroxyethyl terephthalate. ,
Hydrogenated e-sphenol A, ethylene oxide adduct or propylene oxide adduct of hydrogenated bisphenol A, trimethylolethane, trimethylolpropane,
Glycerin, pentaerythritol and 2,2.4-
Trimethylpentane-1,3-diol and the like can be used.

(rl) Regarding component (B): Next, the copolymer containing a (β-methyl)glycyl group as component (B) described above has an Mn of 300 to s, o
oo, preferably in the range of 500 to 6,000, glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate and β
- 1a selected from methylglycidyl methacrylate
i or more (β-methyl)glycidyl (meth)acrylate 10 to 95% by weight, preferably 20 to 60% by weight, hydroxyl group-containing vinyl monomer 0 to 60% by weight, preferably 0 to
20% by weight, and 5 to 90% by weight of other vinyl monomers
%, preferably from 40 to 80% by weight.

If the molecular weight of such a copolymer is lower than 300, the mechanical strength of the resulting coating film will be insufficient, and smoke will be emitted when the coating film is baked.

If it exceeds this, not only will the resulting coating film be poor in sharpness or smoothness, but also the compatibility between the resins will be poor, the crosslinking reaction will not be able to proceed sufficiently, and the strength of the coating film will be poor. It is also inappropriate if the animals are out of alignment.

Furthermore, if the amount of (β-methyl)glycidyl (meth)acrylate alone is reduced by more than 10% by weight, the curing reaction with the polyester resin (4) component will be insufficient and good physical properties will not be obtained.

Examples of the (β-methyl)glycidyl (meth)acrylate mentioned above include glycidyl acrylate, glycizol methacrylate, β-methylglycidyl acrylate, and β-methylglycidyl methacrylate.

Furthermore, if necessary, a hydroxyl group-containing vinyl monomer can be copolymerized. Such a monomer has improved compatibility with the polyester resin component (4) by its use;
The degree of crosslinking can be increased by reaction with blocked incyanate.

Such hydroxyl group-containing vinyl monomers include mono(meth)acrylic esters and monocrotonic esters of polyhydric alcohols, allyl alcohol, monoallyl ethers of polyhydric alcohols, Plaxel FM, FA Nanatsuma (Daicel Chemical Industries, Ltd.) Kaguro 2-chton addition monomer), hydroxyethyl vinyl ether, etc. Examples of polyhydric alcohols that can be used include ethylene glycol, I-lyethylene glycol, globylene glycol, polyclopylene glycol, 1.3-7" ethylene glycol, 1.4-2 terene glycol, I,6-hexanediol, etc. Dihydric alcohols such as glycerin, trimethylolpropane, trimethylolethane, and polyhydric alcohols such as pentaerythritol can also be used, as well as fumaric acid nohydroxyethyl ester, heptalic acid! hydroxyethyl ester, and the like.

In the present invention, other copolymerization components may be used in addition to the above-mentioned (β-methyl)glycidyl (meth)acrylate and the optionally used hydroxyl group-containing vinyl monomer. Examples of such other vinyl monomers include various (meth)acrylic acid esters, (meth)acrylonitrile, and (meth)acrylamide other than the above-mentioned (β-methyl)glycituru (meth)acrylate and hydroxyalkyl ester (meth)acrylate. , 7-malic acid diester, mannic acid diester, itaconic acid diester, or styrene are representative examples. In particular, among (meth)acrylic acid esters, cyclohegygyl methacrylate, cellosolve methacrylate, and styrene are suitable because they have excellent compatibility with the polyester resin carrier component.

Of course, in addition to this, any material can be used as long as it can be copolymerized with the glycidyl (meth)acrylate.

There are no particular restrictions on the method for producing the copolymer component CB), and well-known and commonly used methods can be applied as they are, but a solution polymerization method is particularly recommended because the molecular weight can be easily adjusted.

Regarding the GiD (C) component; Typical block inocyanates as the Q component are aliphatic, aromatic, or cyclic groups such as xylylene soocyanate, inholone diisocyanate, or hequinamethylene diisocyanate. The free isocyanate group contained in the adduct of incyanate and an active hydrogen compound can be removed using methanol, isopronoyl alcohol,
It is blocked with a known and commonly used blocking agent such as butanol, ethyl lactate or ε-cagloctam.

Metallic materials, such as rBF-1540J (Nishi Pitch, manufactured by Huls), which generate incyanate groups when heated, can also be used.

(ψ Regarding the (6) component; ■) The aliphatic dibasic acid that is the component has the general formula HOO
C-R-COOH (17 in the formula) R has 1 to 2 carbon atoms
It is represented by a linear or branched alkylene group, and typical examples include mineral, succinic acid, adipic acid, pimelic acid, speric acid, azelaic acid, sepacic acid, and decane. - Examples include zocargenic acid and blufflic acid. Among these, those having a long carbon number of 8 or more are suitable for use from the viewpoint of the appearance of the coating film.

Therefore, the present invention provides the above-mentioned polyester resin component, the glycidyl group-containing copolymer (B) component, and! Rockisocyanene) (C) component and aliphatic dibasic acid (
b) A composition for powder coating is made by blending the components in a specific ratio, but the functional groups present in each component are
/& The ratio of epoxy groups to xyl groups and the ratio of hydroxyl groups to free incyanate groups are each 0.5 to 1.
It is desirable to keep it within the range of 5. Also, the force N of the aliphatic dibasic acid (6) component and the ff polyester resin (4) component?
The ratio of xyl groups is preferably 2.0 or more, and if it is less than 2.0, the effects of the present invention will not be sufficiently exhibited.

The thus obtained resin composition for powder coating of the present invention includes:
Additionally, if necessary, pigments or other fillers, flow modifiers such as 2-ethylhexyl acrylate polymers or silicones, and optionally various curing catalysts such as amines, imidazoles or organotin compounds,
Certain h can be blended with various resins such as epoxy resins or petroleum resins in order to improve the physical properties of the coating film.

The resin composition for powder coating of the present invention is kneaded using a known and commonly used mixer such as an extruder, and then pulverized to form a powder coating.

As a powder coating method, it is 1! Known and commonly used methods such as painting or fluid dip coating can be applied as is.

〔Example〕

Next, the present invention will be explained in more detail with reference to Reference Examples, Examples, and Comparative Examples. In the following, parts refer to parts by weight unless otherwise specified.

Reference Example 1 [Preparation Example of $Reester Resin (4) Component] A mixture consisting of 344 parts of ethylene glycol, 1,348 parts of neopentyl glycol, 1,796 parts of trimethyl terephthalate and 1.8 parts of zinc acetate was prepared. Gradually increase the temperature to 210C while removing the generated methanol from the system.
After adding 596 parts of terephthalic acid, 740 parts of isophthalic acid, 80 parts of anovic acid and 2 parts of diptyltin oxide, the temperature was increased to 24% over 10 hours.
The temperature was raised to 0°C.

Next, the temperature of the obtained reaction product was lowered to 180°C, 136 parts of trimellitic anhydride was added, and the reaction was continued at the same temperature to obtain an acid value of 24, a hydroxyl value of 14, and a softening point of 1.
At 14°C, a polyester resin (4) component having a Mn of 4,000 was obtained. Hereinafter, this will be abbreviated as resin (A-1).

Reference Example 2 [Preparation example of polyester resin (4) component] 336 parts of ethylene glycol, 1,316 parts of neopentyl glycol, 1,752 parts of trimethyl terephthalate
and 1.8 parts of zinc acetate,
210 gradually while removing generated methanol from the system.
After raising the temperature to ℃, 1,500 parts of terephthalic acid and 2 parts of diptyltin oxide were added, and the temperature was raised to 240''C over 10 hours, and the reaction was continued at the same temperature to increase the acid value. 15, hydroxyl value is 15, and softening point is 11.
A 4fl) ester resin matrix component was obtained at 7° C. and having an Mn of 3,700. Hereinafter, this will be abbreviated as resin (A-2).

Reference Example 3 [Copolymer ■) Preparation example of component] 25 parts of glycidyl methacrylate, 15 parts of 2-hydroxypropyl methacrylate, 30 parts of cyclohexyl methacrylate
parts, n-butyl acrylate 10 parts, styrene 20 parts,
t-butylno'? - A mixture consisting of 1 part of Henshade and 0.5 part of cumene hydrono or monooxide was added dropwise under pressure to 100 parts of xylene heated to 150 DEG C. to polymerize. After the polymerization reaction, xylene was removed to obtain the desired polymer having Mn of i and soo. Hereinafter, this will be abbreviated as copolymer (B-1).

Reference Example 4 [Example of Preparation of Copolymer (B) Component] Using the same method as in Reference Example 3, 25 parts of glycidyl methacrylate,
20 parts of cyclohexyl methacrylate, 20 parts of n-butyl methacrylate, and 35 parts of styrene were polymerized, and M
A polymer containing no hydroxyl groups with n of 1,600 was obtained. Hereinafter, this will be abbreviated as copolymer (B-2).

Reference Example 5 [Preparation example of copolymer (B) component] 1.5 parts of glycidyl methacrylate, 15 parts of 2-hydroxyglobil methacrylate, 6.0 parts of cyclohexyl methacrylate, 1.0 parts of n-butyl acrylate. A mixture of 4.5 parts of azobisisobutyronitrile and 4.5 parts of azobisisobutyronitrile was added dropwise to 100 parts of xylene under normal pressure, and polymerized while refluxing. part was added and polymerized. After the polymerization reaction, xylene was removed to obtain the desired polymer having Mn of 3,100.

Hereinafter, this will be abbreviated as copolymer (B-3).

Examples 1 to 5 The components shown in Table 1 were triblended, then kneaded using an extruder, cooled, and then pulverized to obtain various powder coatings. Thereafter, the powder coating was applied to a steel plate treated with zinc phosphate, and then baked at 180° C. for 20 minutes to obtain a cured coating.

The various performances of each of the coating films thus obtained were investigated. The results are shown in Table 1.

Comparative Examples 1 to 3 Same as Examples 1 to 5 except that the aliphatic dibasic acid was omitted and the blending ratio was changed as shown in Table 1 according to the amount of functional groups in the copolymer. A control powder coating was prepared and then a cured 11i film was obtained and the performance of the coating was then investigated. The results are shown in Table 1.

As shown in Table 1, the coating films obtained from the powder coating composition of the present invention were superior in hardness, mechanical properties, weather resistance, etc. compared to those of the comparative examples. Recognize.

〔effect〕

The resin composition for powder coating of the present invention has hardness, mechanical properties,
It can provide a coating film with excellent stain resistance and weather resistance.

Agent: Patent Attorney Katsutoshi Takahashi

Claims (1)

[Claims] 1. (A) An acid value of 5 to 100 mgKOH/g, a hydroxyl value of 5 to 100 mgKOH/g, and a softening point of 80 to 15.
a polyester resin having a number average molecular weight of 1,000 to 10,000 at 0°C; (B) one or more vinyl monomers selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, and β-methylglycidyl methacrylate; The number average molecular weight obtained from ~95% by weight, 0 to 60% by weight of the hydroxyl group-containing vinyl monomer, and 5 to 90% by weight of other vinyl monomers is 30%.
1. A resin composition for a powder coating, comprising a copolymer having a molecular weight of 0 to 8,000, (C) a blocked isocyanate, and (D) an aliphatic dibasic acid.