JPS63278976A - Resin composition for powder coating - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a new and useful resin combination acid for powder coatings, and more specifically, to a combination of a specific polyester resin and a specific vinyl copolymer. Furthermore, the resin composition for powder coatings is composed of blocked isocyanate and/or non-blocked isocyanate containing uretdione bonds, and has excellent properties such as corrosion resistance, weather resistance, and stain resistance, as well as the physical properties and appearance of the coating film. relating to things.

[Prior art and problems to be solved by the invention] Generally,
Carboxyl group-containing polyester resin and (β-methyl)
Powder coatings composed of glycidyl group-containing vinyl polymer resins and blocked isocyanates have good physical properties and appearance, and are highly weather resistant, so they are mainly used for outdoor applications such as building materials and exteriors. Applied.

However, powder coatings with such a structure are different from conventional powder coatings such as powder coatings made of a hydroxyl group-containing polyester resin and blocked isocyanate, or powder coatings made of a carboxyl group-containing polyester resin and an epoxy resin. The corrosion resistance and stain resistance of the cured coating film are poor.

Various attempts have been made to overcome these drawbacks, such as adding epoxy resins, but none of them are sufficient, and instead end up deteriorating weather resistance and physical properties, which makes them difficult to use for outdoor applications. The reality is that the application to home appliances and other products has been delayed.

[Means for solving problems]

However, in view of the various drawbacks of the above-mentioned conventional techniques, the present inventors have made extensive studies and found that a specific vinyl monomer containing a phosphorus atom is added to a polyester resin having both a carboxyl group and a hydroxyl group. , (β−
A powder coating formed by combining a vinyl copolymer with a specific molecular weight range containing a vinyl monomer containing a methyl) glycidyl group as an essential monomer and a blocked isocyanate and/or a non-blocked isocyanate containing a uretdione bond has physical properties, The present invention was completed based on the discovery that a cured coating film having excellent appearance and weather resistance, as well as extremely excellent corrosion resistance and stain resistance, can be obtained.

That is, in the present invention, the essential film-forming component has an acid value of 5 to 100 ■KOH/g (hereinafter, the unit is abbreviated as abbreviation).

), the hydroxyl value is 5 to 100 ■KOH/g (hereinafter, the unit is abbreviated), and the number average molecular weight is 1,000 to 10
．． 000, and the softening point according to the ring and ball method (hereinafter the same) is 8
60-96 of polyester resin (A) at 0-150°C
Parts by weight and a small amount selected from the group consisting of glycidyl acrylate (G^), glycidyl methacrylate (GMA), β-methylglycidyl acrylate (MGA) and β-methylglycidyl methacrylate (MGMA).
Both have 10 to 95% by weight of one kind of (β-methyl)glycidyl group-containing vinyl monomer (b-1) and are copolymerizable with the (β-methyl)glycidyl group-containing vinyl monomer (b-1). 0 to 89 of the vinyl monomer (b-2),
99% by weight and 0 of the phosphorus atom-containing vinyl monomer (b-3) represented by the general formula
．． 01 to 10% by weight, the number average molecular weight is 3
3 to 40 of the vinyl copolymer (B) having both a (β-methyl)glycidyl group and a phosphorus atom of 00 to 8.000
The object of the present invention is to provide a resin composition for a powder coating comprising 1 to 2 parts by weight of a blocked isocyanate and/or a non-blocked isocyanate (C) containing a uretdione bond.

The configuration of the present invention will be explained in detail below.

First, the constituent components will be explained.

(i) Regarding the polyester resin (A) component; The polyester resin as the component (A) described above has an acid value of 5 to 100, preferably 10 to 70, and a hydroxyl value of 5.
~100, preferably 10-70, with a softening point of 80-1
50°C, preferably 100-130°C, and side 1
,000-10,000, preferably 2.000-5,
000, but as long as it falls within this range, it may have a branched structure or a linear structure.

As for the preparation method of the polyester resin, any well-known and commonly used method can be applied as is without any particular restriction, and both the acid component and the alcohol component are well-known and commonly used dibasic acids, tribasic acids or higher polybasic acids. Ingredients and dihydric alcohol and polyhydric alcohol components of trihydric alcohol and higher can be used.

Therefore, only typical acid components and alcohol components will be listed. First, acid components include terephthalic acid, isophthalic acid, phthalic acid, methylterephthalic acid, trimellitic acid, pyromellitic acid, and their anhydrides; Or adipic acid, sebacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid,
Methyl-tetrahydrophthalic acid, hexahydrophthalic acid, methyl-hexahydrophthalic acid and their anhydrides, etc., while alcohol components include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4- Butanediol, 1,6-hexanediol, neopentyl glycol, bishydroxyethyl terephthalate, hydrogenated bisphenol A, ethylene oxide adduct or propylene oxide adduct of hydrogenated bisphenol A, trimethylolethane, trimethylolpropane, glycerin, Pentaerythritol and 2,2,4-)trimethylpencune-1,3-diol can be used.

In addition, in preparing the present 8-polyester, it goes without saying that the following epoxy group-containing compounds can be used in combination with an acid component. For example, representative examples include n-butyl glycidyl ether, phenyl glycidyl ether, persatic acid glycidyl ester, glycide, and bisphenol A type epoxy resin.

(ii) Regarding the vinyl copolymer (B) component having both a (β-methyl)glycidyl group and a phosphorus atom: Next, a (β-methyl)glycidyl group and a phosphorus atom as the component (B) described above are combined. The vinyl copolymer has a leaf count of 300 to 8,000, preferably 500 to 6,000, and includes glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, and β-methylglycidyl methacrylate. 10 to 95% by weight, preferably 15 to 95% by weight of one or more (β-methyl)glycidyl (meth)acrylates selected from
80% by weight and 0 to 89% of other vinyl monomer (b-2) copolymerizable with the vinyl monomer (b-1).
．． 99% by weight, preferably 19.95-80% by weight,
0.01 to 10% by weight, preferably 0.05 to 5% by weight of one or more phosphorus atom-containing vinyl monomers (b-3) as shown in the above general formula (1) are co-coated by a conventional method. Refers to the product obtained by polymerization.

Here, if the amount of the (β-methyl)glycidyl group-containing vinyl monomer (b-1) used is less than 10% by weight, the compatibility with the above-mentioned polyester resin (A) becomes poor, and as a result, the resin Since the reaction with (A) becomes insufficient, a good cured coating film cannot be obtained, and conversely, 95% by weight
If it exceeds this, the storage stability of the paint will deteriorate.
Neither is preferable.

On the other hand, if the amount of the phosphorus atom-containing vinyl monomer (b-3) used is less than 0.01% by weight, good corrosion resistance of the coating film cannot be obtained and the effects of the present invention cannot be expected to be exhibited. On the other hand, if the content exceeds 10% by weight, the storage stability of the paint will deteriorate, so both are not preferred.

In addition, if the molecular weight of the polymer (B) component 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 .000, not only will the sharpness or smoothness of the resulting coating film be poor, but also the compatibility between the resins will be poor, the crosslinking reaction will not proceed sufficiently, and the strength of the coating film will also be poor. Therefore, it is inappropriate in either case.

In addition, other vinyl monomers having copolymerizability (
b-2), excluding (β-methyl)glycidyl group-containing vinyl monomers, containing 1 to 1 carbon atoms represented by ethyl (meth)acrylate and butyl (meth)acrylate;
Alkyl (meth)acrylate having an alkyl group of 22, styrene, vinyltoluene, t-butylstyrene, α-methylstyrene, 2-ethoxyethylene (meth)
Unsaturated carboxylic acids such as acrylate, (meth)acrylonitrile, cyclohexyl, (meth)acrylate, (meth)acrylic acid, maleic acid, fumaric acid or itaconic acid; β = hydroxyethyl (meth)acrylate, β-hydroxypropyl (meth) ) acrylate or vinyl monomers containing hydroxyl groups such as β-hydroxybutyl (meth)acrylate; diesters with monohydric alcohols having alkyl groups such as maleic acid or fumaric acid; (meth)acrylamide or N- (Meth)acrylamide such as alkoxymethylated (meth)acrylamide; N,N-dialkylaminoalkyl (meth)acrylate lfi; Fluorine-containing vinyl monomers such as vinyl acetate, hexafluoropropylene, and tetrafluoroethylene are used. .

These vinyl monomers (b-2) can be used alone or in a mixture of two or more depending on the desired coating performance.

In the present invention, it is of course possible to use any monomer other than the above-mentioned monomers as long as they can be copolymerized.

There is no particular restriction on the method for producing the copolymer (B) component described above, and well-known and commonly used methods can be applied as they are. However, a solution polymerization method is recommended because it allows easy adjustment of the molecular weight, and the desired polymer can be obtained by removing the solvent after polymerization. That is, it is preferable to carry out the polymerization using a known and commonly used solvent such as toluene, xylene, and ethyl acetate in the presence of a known and commonly used radical generator such as azobisisobutyronitrile and benzoyl peroxide. Chain transfer agents such as lauryl mercaptan, octyl mercaptan, 2-mercaptoethanol, octyl thioglycolate, 3-mercaptopropionic acid or α-methylstyrene dimer can also be used as molecular weight regulators.

(iii) Regarding the blocked isocyanate (C) component; The blocked isocyanate as the (C) component is an aliphatic compound such as xylylene diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate,
Free isocyanate groups contained in aromatic or alicyclic isocyanates, or adducts of these with active hydrogen compounds, are blocked using known and commonly used blocking agents such as methanol, isopropanol, butanol, ethyl lactate or ε-caprolactam. The one blocked by is a typical example. Typical active hydrogen compounds include various low molecular weight compounds such as ethylene glycol, butylene glycol, trimethylolpropane, glycerin, ethylenediamine or hexamethylenediamine,
Included are various high molecular weight materials such as polyols, polyethers, polyesters or polyamides.

Furthermore, a non-blocked isocyanate compound which does not contain the above-mentioned blocking agent and has, for example, a uretdione bond, can also be used as one of the components (C).

Therefore, the resin composition for powder coating of the present invention comprises the above-mentioned polyester resin (A), a vinyl copolymer (B) containing a (β-methyl)glycidyl group and a phosphorus atom, and a block isocyanate. and/or uretdione bond-containing non-blocked isocyanate) (C), and the ratio of these components used is 60-96:3-40:1-20.
, preferably within the range of 65 to 90 nia to 30:3 to 15 (parts by weight), and the ratio of epoxy groups to carboxyl groups among the functional groups (reactive groups) of each component. It is desirable to maintain the ratio of hydroxyl groups to free isocyanate groups within the range of 0.5 to 1.5, respectively.

The thus obtained resin composition for powder coating according to the present invention may further contain a pigment or other filler, a flow regulator such as a 2-ethylhexyl acrylate polymer or silicone, if necessary. It goes without saying that, depending on the case, various catalysts such as aminos, imidazoles or organic tin compounds, or various resins such as epoxy resins or petroleum resins may also be incorporated.

The powder coating composition of the present invention is kneaded using a known and commonly used kneading machine such as an extruder, and then pulverized to form a powder coating. As the powder coating method, known and commonly used methods such as electrostatic coating or fluidized dip coating can be used as they are.

〔Example〕

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

Reference Example 1 [Preparation example of polyester resin (A) component] 344 parts of ethylene glycol, 1,348 parts of neopentyl glycol, 1,7 parts of dimethyl terephthalate
A mixture consisting of 96 parts of zinc acetate and 1.8 parts of zinc acetate was charged, and while the methanol produced was removed from the system, 2
The temperature was raised to 10°C, and 596 parts of terephthalic acid, 740 parts of isophthalic acid, 80 parts of adipic acid, and 2 parts of dibutyltin oxide were added, and the temperature was raised to 240°C over 10 hours. .

Next, when the temperature of the obtained reaction product (intermediate polyester) was lowered to 200°C, 420 parts of trimellitic anhydride was added thereto and reacted at the same temperature for 2 hours to obtain an acid value of 60 and a hydroxyl group. A desired resin (A) was obtained which had a value of 5, a softening point of 113° C., and a number average molecular weight (side 1) of 3.500. Hereinafter, this will be abbreviated as resin (A-1).

Reference example 2 [same as above] 336 parts of ethylene glycol, 1.316 parts of neopentyl glycol, 1,7 parts of dimethyl terephthalate
A mixture consisting of 52 parts of zinc acetate and 1.8 parts of zinc acetate was charged, and 2
After raising the temperature to 10°C, 1,500 parts of terephthalic acid and 2 parts of dibutyltin 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 15, softening point 11
A target resin (A) having a temperature of 7° C. and a rabbit value of 3,700 was obtained. Hereinafter, this will be abbreviated as resin (A-2).

Reference Example 3 [Preparation example of vinyl copolymer (B)] 30 parts of GMA, 20 parts of n-butyl methacrylate, 15 parts of ethyl cellosolve methacrylate, 10 parts of n-butyl acrylate, 24.5 parts of styrene. , 0.5 parts of 2-methacryloyloxyethyl acid phosphate, 6 parts of azobisisobutyronitrile and 1.0 parts of t-butyl perbenzoate were added in 100 parts of xylene at 125°C. The mixture was added dropwise over a period of time to effect copolymerization, and the xylene was then removed to obtain a target copolymer (B) having a particle size of 1,500. Hereinafter, this will be abbreviated as copolymer (B-1).

Reference Example 4 [Same as above] Instead of 0.5 part of 2-methacryloyloxyethyl acid phosphate, 0.01 part of dioctyl-2-
A target copolymer (B) having a feather size of 1,600 was obtained in the same manner as in Reference Example 3, except that acryloyloxyethyl phosphate was used and the amount of styrene was changed to 24.99 parts. . Hereinafter, this will be described as a copolymer (B-2
).

Reference Example 5 [Same as above] 25 parts of MGMA, 10 parts of isobutyl methacrylate, 10 parts of 2-ethylhexyl methacrylate, 25 parts of methyl methacrylate, 25 parts of styrene, and 5 parts of diphenyl-2-methacryloyloxyethyl phosphate. In the same manner as in Reference Example 3, except that a mixture of vinyl monomers consisting of
A desired copolymer (B) named 900 was obtained. Hereinafter, this will be abbreviated as copolymer (B-3).

Reference Example 6 [Same as above] The amount of 2-methacryloyloxyethyl acid phosphate used was changed to 0.3 parts, and at the same time, 0.2 parts of diphenyl-2-methacryloyloxyethyl phosphate was also used, and azobis A target copolymer (B) having a H1 of 5.000 was obtained in the same manner as in Reference Example 3, except that the amount of isobutyronitrile used was changed to 2 parts. Hereinafter, this will be abbreviated as copolymer (B-4).

Reference Example 7 [Preparation example of a control vinyl copolymer containing a minute amount of a phosphorus atom-containing vinyl monomer] The amount of 2-methacryloyloxyethyl acid phosphate used was changed to 0.05 parts, and at the same time the amount of styrene used was changed to 24 parts. A control vinyl copolymer having a weight ratio of 1.550 was obtained in the same manner as in Reference Example 3, except that the amount was changed to 995 parts. Hereinafter, this will be abbreviated as copolymer (B'-1).

Reference Example 8 [Preparation example of a control vinyl copolymer containing a large amount of phosphorus atom-containing vinyl monomer] The amounts of 2-methacryloyloxyethyl acid phosphate and styrene used were 11 parts and 14 parts, respectively.
Mn was 1 in the same manner as Reference Example 3 except that the
, 400 was obtained as a control vinyl copolymer. below,
This is abbreviated as copolymer (B'-2).

Examples 1 to 5 and Comparative Examples 1 to 5 Each component as shown in Table 1 was triblended in a predetermined ratio, then kneaded in an extruder, and then cooled.
It was pulverized to obtain various powder coatings.

Thereafter, each powder coating was applied to a zinc phosphate-treated steel plate, and then baked at 180° C. for 20 minutes to obtain each cured coating.

The performance of each cured coating film thus obtained was compared and examined. The results are summarized in the same table.

Notes to Table 1 1) Blocked isocyanate manufactured by Hüls, West Germany 2) Non-blocked isocyanate containing uretdione bonds manufactured by the same company 3) Bisphenol A type epoxy resin manufactured by Dainippon Ink & Chemicals 4) Manufactured by BASP, West Germany Acrylic spreading agent 5)
Titanium oxide manufactured by British Titanium Ltd. 6) "Mitsubishi Uni" [Mitsubishi Pencil Product] 7) After making a cut in the paint film and spraying it for 700 hours at 35℃, apply cellophane tape to the cut part. 8) Red marker contamination degree, that is, (ΔEt/ΔEl)X1
It shows the color difference between the value calculated from 00 and the value after applying red marker and wiping it off.

9) Gloss retention after 800 hours on the Sunshine Weatherometer 10) After the paint was prepared and stored at 40°C for one month, the cured film obtained from this paint was evaluated for the painted surface. Smoothness determined visually [Effects of the invention] As is clear from the results in Table 1, the resin composition for powder coatings of the present invention has excellent physical properties and appearance, as well as corrosion resistance, weather resistance, and stain resistance. I know it's something.

Agent Patent Attorney Katsutoshi Takahashi Procedural Amendment June 1988 Director-General of the Patent Office Kuro 1) Mr. Yu Akira 1, Indication of the case 1988 Patent Application No. 113488 2, Name of the invention Resin for powder coatings Composition 3, Relationship with the amended person case Patent applicant: 3-35-58 Sakashita, Itabashi-ku, Tokyo (288) For the representative of Dainippon Ink and Chemicals Co., Ltd.
Shigeru Kuni Mura 4, Agent 5, Dainippon Ink & Chemicals Co., Ltd., 3-7-20 Nihonbashi, Chuo-ku, Tokyo 103, Column 6 of "Claims" of the specification subject to the amendment, Contents of the amendment ( 1) Correct the statement of the scope of claims as shown in the attached sheet.

Above (Attachment) Revised Claims (Japanese Patent Application No. 113488/1988) "The acid value is 5 to 100 a7KOH/g, the hydroxyl value is 5 to 100 ■KOH/g, and the number average molecular weight is 1. ,0
00 to 10.000, and the softening point according to the ring and ball method is 80.
Will it be ~150℃? 60 to 96 parts by weight of polyester resin; and (B) at least one (β-methyl)glycidyl group-containing vinyl selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, and β-methylglycidyl methacrylate. 10 to 95 tS of monomer (b-1) and the (β-methyl)glycidyl group-containing vinyl monomer (b-
Other vinyl monomers (b-2) copolymerizable with 1)
and one or more phosphorus atom-containing vinyl monomers represented by the general formula (b
-3) of a vinyl copolymer having both a (β-methyl)glycidyl group and a phosphorus atom and having a number average molecular weight of 300 to 8,000 obtained from 0.01 to 10% by weight of
40 parts by weight, and (1 to 20 parts by weight of a blocked isocyanate and/or a uretdione bond-containing non-blocked isocyanate) as essential components.

Claims (1)

[Scope of Claims] (A) Oxidation is 5 to 100 mgKOH/g, hydroxyl value is 5 to 100 mgKOH/g, and number average molecular weight is 1,00
0 to 10,000, and the softening point by the ring and ball method is 80 to
60 to 96 parts by weight of polyester resin at 150°C;
(B) 10 to 95 weight of at least one (β-methyl)glycidyl group-containing vinyl monomer (b-1) selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, β-methylglycidyl acrylate, and β-methylglycidyl methacrylate % and the (β-
0 to 0 of other vinyl monomers (b-2) that are copolymerizable with the vinyl monomer (b-1) containing a methyl) glycidyl group.
89.99% by weight, and the general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [ I ] However, R_1 in the formula is a hydrogen atom or a methyl group, and R_
2 and R_3 are each a hydrogen atom which may be the same or different, an alkyl group consisting of C_1 to C_8, C_
6-C_1_0 aryl group or C_7-C_1_
In the aralkyl group 2, A means an alkylene group C_1 to C_1_4. One or more phosphorus atom-containing vinyl monomers (b
-3) of a vinyl copolymer having both a (β-methyl)glycidyl group and a phosphorus atom and having a number average molecular weight of 300 to 8,000 obtained from 0.01 to 10% by weight of
and (C) 1 to 20 parts by weight of a blocked isocyanate and/or a uretdione bond-containing non-blocked isocyanate as essential components.