JPS63258962A - Production of graft-modified polyester resin for powder coating - Google Patents

Abstract

PURPOSE:To obtain the titled thermosetting type resin, having excellent pigment dispersibility and capable of forming films having improved appearance and surface hardness, by graft reacting a polyester resin with a nitrogen atom- containing vinyl monomer in a specific amount. CONSTITUTION:The aimed resin obtained by graft reacting a polyester resin with 0.01-5.0wt.%, preferably 0.05-3wt.% nitrogen atom-containing vinyl monomer [e.g. N,N-dialkylaminoalkyl (meth)acrylate or N,N-dialkylaminoalkyl (meth) acrylamide]. Furthermore, the above-mentioned polyester resin component preferably has unsaturation points used for the graft reaction with the nitrogen- containing vinyl monomer component.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to IJ ester resin for powder coatings.

More specifically, the present invention relates to a method for producing a graft-modified polyester resin with extremely excellent pigment dispersibility for thermosetting powder coatings.

(Prior Art and Problems to be Solved by the Invention) Conventionally, polyester resins have been widely used as binders for thermosetting powder coatings due to their crushed mechanical strength and coating film properties. however.

Pigment dispersibility is highly sensitive, and as a result, the amount of pigment used is limited to an amount that does not impair the aesthetic appearance of the paint film. There are limits to performance improvement. Furthermore, in powder coatings that are thermally melted from a solid state and then thermally cured, the pigment dispersibility described above governs the fluidity during hot melting and is an extremely important property in providing a good coating film appearance. . Pigment dispersibility of powder coatings using polyester resin as a binder is generally determined by using acrylic resin or epoxy resin. -Although both of these methods are excellent, they are still insufficient, as mentioned above, and the current situation is that nothing satisfactory has been achieved.

(Means for Solving the Problems) As a result of intensive research aimed at improving the pigment dispersibility in the prior art described above and thereby improving performance such as coating film appearance and surface hardness, the present inventors found that polyester resin The present inventors have discovered that the pigment dispersibility can be significantly improved by graft copolymerizing a nitrogen atom-containing vinyl monomer to the pigment, thereby completing the present invention.

To summarize the present invention, 1. The present invention is a grafting material for powder coatings which has excellent pigment dispersibility and is characterized by being made by grafting 0.01 to 5.0% by weight of a nitrogen atom-containing vinyl monomer onto a polyester resin. The present invention relates to a method for producing a modified I-lyester resin.

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

Any polyester resin component serving as a graft base used in the present invention can be used as long as it has an unsaturated point that can be graft copolymerized with the nitrogen atom-containing vinyl monomer component described below.

There are no particular restrictions.

There are no particular restrictions on the method for preparing the polyester resin, and any well-known and commonly used method can be applied as is.As for the acid component and the alcohol component, well-known and commonly used dibasic acids and/or polybasic acids may be used. Also, dihydric alcohols (glycols) and/or polyhydric alcohols can be used as they are, but among these, typical acid components include terephthalic acid, isophthalic acid, phthalic acid, methylterephthalic acid, and trimellitic acid. ,
Pyromellitic acid and its anhydrides or adipic acid, sepacic acid, succinic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, methyl-tetrahydrophthalic acid,
Hexahydrophthalic acid.

Examples include methyl-hexahydrophthalic acid and its anhydrides, while typical alcohol components include ethylene glycol, propylene glycol, l
l3-butanediol, 1.4-butanediol, 1.
6-hexanediol, neointyl glycol, isopentyl glycol, bishydroxyethyl terephthalate, hydrogenated hxphenol A, ethylene oxide adduct of hydrogenated bisphenol A, propylene oxide adduct of hydrogenated bisphenol A, trimethylolethane.

trimethylolpropane, glycerin, pentaerythritol and 2,2.4-) sameterpentane-1,
Although there are 3-diols and the like, monoepoxy compounds can also be used as one of the glycols in the present invention.

The polyester resin component used in the present invention is as follows.

It is desirable to have an unsaturated point that can be subjected to a graft reaction with the nitrogen atom-containing vinyl monomer component described below, and the following method is typical for securing this point.

(1) Maleic acid % 7 Unsaturated dicargenic acids such as maleic acid and itaconic acid are used as raw materials for polyester resin production in advance and subjected to a condensation reaction, or the hydroxyl groups of the polyester resin are reacted with dicarmenic anhydride to form unsaturated groups. How to introduce.

This method is the most preferred from the viewpoint of pigment dispersibility, which is the object of the present invention, and the amount of unsaturated dicarmenic acid used is 0.01 to 5% by weight, particularly preferably 0.05% by weight.
~3% by weight. When the ratio is less than 0.01% by weight, the effect is only expected, but when the ratio exceeds 5% by weight, the resin becomes extremely viscous, which causes a loss in the smoothness of the coating film.

(11) General formula %formula% (R4: hydrogen atom or methylol group.

R2: C4-C5 alkyl group) A method of adding a vinyl hexamer containing an isocyanate group represented by R2: C4-C5 alkyl group to the remaining hydroxyl groups of a polyester resin.

(iii) A method of adding glycidyl (meth)acrylate to residual calgexi groups of a polyester resin.

The above is a typical example of introducing an unsaturated group into the /IJ ester resin, and this makes it possible for the polyester resin component to be graft copolymerized with the nitrogen atom-containing vinyl monomer described below. It goes without saying that the method of introducing a saturated group is not limited to the method described above.

Next, the nitrogen atom-containing vinyl monomer component to be graft-reacted to the polyester resin component, which is an essential condition of the present invention, will be explained. Examples of such nitrogen atom-containing vinyl monomer components include N,N-dialkylaminoalkyl (meth)acrylate.

N,N-dialkylaminoalkyl(meth)acrylamide, (meth)acrylamide, N-methylol(meth)acrylamide, N,N-dialkyl(meth)acrylamide, diacetone(meth)acrylamide, acryloyl, morpholine, N-alkoxy Methyl (meth)acrylamide, N-vinylpyrrolidone, acrylonitrile, N,N-dialkylaminoalkylmaleimide,
Vinylimidazole and the like and derivatives thereof are used.

The amount used is 0.01 to 5% by weight, more preferably 0.01 to 5% by weight.
．． 05-3% by weight. If the amount is less than 0.01% by weight, the effect cannot be expected, and if it exceeds 5% by weight, problems will arise in the storage stability of the paint, which is not preferable.

, 1 The nitrogen atom-containing vinyl monomer can be grafted onto the polyester resin by a conventional graft reaction. Most conveniently, the graft reaction may be carried out with the nitrogen atom-containing bisulfur monomer in the presence of a 4-liester resin having an unsaturated group that participates in the graft reaction, in the presence or absence of a radical polymerization initiator.

In the present invention, other vinyl monomers can be used in addition to the nitrogen-containing vinyl monomer component during graft copolymerization. For example, styrene.

Styrene and its derivatives such as P-mechanical butyl styrene; Alkyl acrylates such as methyl acrylate, ethyl acrylate and butyl acrylate; Alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate; Acid monomers such as acrylic acid and methacrylic acid: 2 Hydroxy (meth)acrylates such as hydroxy (meth)acrylate, etc. can be used in combination.

1. In the graft copolymerization of the present invention, polymerization of azobisisobutyronitrile, benzoyl peroxide, tert-butyl perbenzony), /-butyl hydroxide, ditertiary butyl hydroxide, cumene hydroxide, etc. Initiators can be used.

Although the graft copolymerization reaction can be carried out without diluting the polyester resin with an organic solvent, the graft copolymerization reaction is generally carried out in a solution diluted with an organic solvent. The organic solvents used are aromatic ones such as xylene, toluene, Swazol 1000, and Swazol 1500 (Cosmo Oil Co., Ltd. W); ester-based ones such as ethyl acetate, butyl acetate, and cellosolve acetate; methyl ethyl ketone, methyl isobutyl. Ketone-based products such as ketone; alcohol-based products such as 1-butanol and 2-butanol cellosolve; aromatic, aliphatic, and alicyclic mixed-based products such as mineral spirit and Swazol 310, either singly or in combination. It can be used.

In order to carry out a graft copolymerization reaction in a solution and use the resulting resin solution for powder coating, it is preferable to distill off the solvent from the resin solution under normal pressure or reduced pressure.

The thus obtained graft-modified polyester resin of the present invention contains polyisocyanate, blocked isocyanate 1
．． It can be used as a thermosetting powder coating by containing a crosslinking agent component such as an amino resin or an epoxy resin. t
x. It goes without saying that the graft-modified polyester resin of the present invention can be used with addition of known and commonly used paint additives or curing accelerators effective for the crosslinking agent component.

A powder coating can be prepared using the graft-modified polyester resin of the present invention thus obtained by any known method.

A coating film with excellent subsequent performance can be obtained by applying the obtained nine powder coatings by a well-known method such as an electrostatic spray method, then a fluidized dipping method, and then baking.

(Examples, etc.) Next, the present invention will be specifically explained with reference to Synthesis Examples, Examples, and Comparative Examples.
All items shall be based on weight.

Synthesis example 1. [Pace polyester resin for graft modification (
Synthesis of A-1)] A mixture consisting of 83 parts of ethylene glycol, 327 parts of neopentyl glycol, 435 parts of dimethyl terephthalate, and 0.4 parts of zinc acetate was removed from the reaction system while removing the generated methanol from the reaction system. The temperature was gradually raised to 210°C, and then the same temperature was maintained for 2 hours to continue the alcohol exchange reaction. Next, 6 parts of trimethylolpropane, 130 parts of terephthalic acid, 224 parts of isophthalic acid, 13 parts of maleic acid and 0.5 part of di-n-butyltin oxide were added thereto, and 240 parts of di-n-butyltin oxide were added over a period of 8 hours.
The temperature was raised to .degree. C., and dehydration condensation was further carried out at the same temperature to obtain /I) ester (A-1) having a hydroxyl value of 40 and an acid value of 7.

Synthesis example 2. [Synthesis of the same (A-2)] A polyester (A-2) having a hydroxyl value of 30 and an acid value of 9 was obtained in the same manner as in Synthesis Example 1 except that 13 parts of maleic acid was changed to 15 parts of itaconic acid.

Synthesis example 3. [Base for comparison - Lyester resin (R-
Synthesis of 1)] 130 parts of terephthalic acid was changed to 135 parts, and the hydroxyl value was 40 in the same manner as in Synthesis Example 1 except for omitting the use of maleic acid.
．． Next, a preester with an acid value of 7 was obtained.

This is referred to as polyester (R-1).

Synthesis example 4. [Pace polyester resin for graft modification (
Synthesis of A-3)] The following polyester (R-1) obtained in Synthesis Example 3 1000
3.5 parts of maleic anhydride was added and reacted for 2 hours to obtain a polyester (A-3) having a hydroxyl value of 38 and an acid value of 9.

Synthesis example 5. [Synthesis of the same (A-4)] Omitted the use of ethylene glycol, 450 parts of neopentyl glycol, 420 parts of dimethyl terephthalate, 20 W of trimethylolpropane, 150 parts of f-phthalic acid,
A hydroxyl value of 5 and an acid value of 35 was prepared in the same manner as in Synthesis Example 1 except that 242 parts of isophthalic acid and 15 parts of maleic acid were used.
A polyester (A-4) was obtained.

Synthesis example 6. [Synthesis of the same (A-5)] 1000 parts of the polyester (A-1) obtained in Synthesis Example 1 was kept at 200°C, and 124 parts of trimellitic anhydride was added and reacted for 2 hours to give an acid value of 70. A polyester (A-5) having a hydroxyl value of 8 was obtained.

Synthesis example 7. [Comparative control paste/diester resin (R-
Synthesis of 2)] The hydroxyl value was 43.Synthesis in the same manner as in Synthesis Example 1 except that 13 parts of maleic acid was changed to 1 part. Polyester with acid value 5 (R-2
) and make friends.

Synthesis example 8. [Synthesis of (R-3)] The same procedure as in Synthesis Example 1 was carried out except that 13 parts of maleic acid was changed to 60 parts and 224 parts of isophthalic acid was changed to 140 parts.The hydroxyl value was 40. A polyester (R-3) with an acid value of 6 was obtained.

Synthesis example 9. [Synthesis of the same (R-4)] 1000 parts of the polyester (R-1) obtained in Synthesis Example 3 was kept at 200°C, and 124 parts of trimellitic anhydride was added and reacted for 2 hours to give an acid value of 70. A polyester (R-4) having a hydroxyl value of 8 was obtained as follows.

Synthesis example 10. (Graft modified polyester resin (GP-
Synthesis of 1)] 300 parts of xylene and 100 parts of butyl acetate were added to 500 m of polyester (A-1), and the temperature was raised to 120°C to dissolve it. Next, 100 parts of xylene.

A mixture of 0.15 parts of dimethylamine ethyl methacrylate and 3 parts of azobisisobutyronitrile was added dropwise to the polyester solution over 1 hour, and the graft reaction was further carried out at the same temperature for 8 hours. Next.

After the grafting reaction was completed, xylene and butyl acetate were distilled off from the resin solution under reduced pressure of 15 wHg to reduce the hydroxyl value to 3.
9. Acid value 7. A graft modified polyester (GP-1) having a softening point (ring and ball method) of 108°C was obtained.

Synthesis example 11. [Synthesis of the same (CP-2)] Same as Synthesis Example 10 except that 0.15 part of dimethylaminoethyl methacrylate was changed to 0.15 part of vinylimidazole.
Hydroxyl value 40. A graft modified/IJ ester (CP-2) having an acid value of 7° and a softening point of 109°C was obtained.

Synthesis example 12. [Synthesis of the same (GP-3)] Using 15 parts of methylef, dimethylaminoethyl, methacrylate) 0
．． The procedure was the same as in Synthesis Example 10 except that 15 parts were changed to 15 parts, and the hydroxyl value was 39 and the acid value was 6. A graft modified polyester (CP-3) having a softening point of 112°C was obtained.

Synthesis example 13. [Synthesis of the same (GP-4)] Polyester (
A-1) was changed to polyester # (A-2), and the hydroxyl value was 28. Graft-modified polyester (CP-4) with an acid value of 8 and a softening point of 118°C.
) was obtained.

Synthesis example 14. [Synthesis of GP-5] Polyester (
1 except that A-1) was changed to polyester (A-3)
In the same manner as in Synthesis Example 12, the hydroxyl value was 39. Acid value 8. Graft modified polyester (GP-5) with a softening point of 108°C
I got it.

Synthesis example 15. [Synthesis of GP-6] Polyester (
A-1) was changed to yN-liester (A-4) and the same procedure as in Synthesis Example 12 was carried out except for the hydroxyl value of 4. Acid value 33. Graft-modified polyester (GP-6) with a softening point of 120°C
).

Synthesis example 16. [Synthesis of the same (CP-7)] Polyester (
1 except that A-1) was changed to polyester (A-5)
In the same manner as in Synthesis Example 12, the hydroxyl value was 7. Graft modified polyester (CP-7) with an acid value of 66 and a softening point of 115°C
I got it.

Synthesis Examples 17 to 20 [Polyester resin for comparison (P
Synthesis of -1) to (P-4)] I polyester A-1) was converted into polyester (R-1).

Polyesters for comparison (P-1), (P-2), (P-2), (P-2), and (P -3), (P-4)
I got it.

Synthesis Example 216 [Synthesis of (P-5)] Same procedure as Synthesis Example 10 except that 0.15 parts of dimethylamine ethyl methacrylate was changed to 0.604 parts, with acid value 7. Hydroxyl value 39
．． Comparative polyester with a softening point of 108°C (P-5
) and make friends.

Synthesis example 22. [Synthesis of the same (P-6)] 30 parts of dimethylaminoethyl methacrylate
The acid value was changed to 6.0 parts, and the same procedure as in Synthesis Example 10 was carried out except for the following. Hydroxyl value 38. A comparative terester (P-6) having a softening point of 109°C was obtained.

Next, the resins obtained in each synthesis example will be evaluated. It is useful for preparing powder coatings such as Comparative Examples 1 to 8.

Example 1 Graft modified polyester (CP-1) 8 Part Q and "Fleran UIJ (block isocyanate manufactured by Bayer)"
20 parts, 100 parts of titanium oxide and "Moda 70-" (
1 part of Monsanto Co., Ltd.'s fluidity regulator) was added thereto, and these were mixed, then kneaded in an extruder, cooled, and pulverized to obtain a powder coating.

Examples 2 to 5 Powder coatings were obtained in the same manner as in Example 1, except that the graft modified polyester (CP-1) was replaced with graft modified polyesters (GP-2) to (GP-5), respectively.

Example 6 100 parts of titanium oxide and 1 part of "Modaflow" were added to 70 parts of graft-modified polyester (CP-6) and 30 parts of "Epiclon 3050J (Dainippon Ink Chemical Co., Ltd., epoxy resin)", and 9. Obtain powder coating in the same manner as in 1.

Example 7 Same as Example 6 except that 70 parts of graft-modified polyester (GP-6) was changed to 50 parts of graft-modified polyester (CP-7), and [Evicron 3050J 30 parts was changed to 50 parts.] A powder coating was obtained.

Example 8 The same procedure as in Example 1 was carried out except that 100 parts of titanium oxide was replaced with 10 parts of precipitated barium sulfate, and 5 parts of rMA-1ooJ (manufactured by Mitsubishi Cargan Co., Ltd., Cargan Black) was added. A powder coating was obtained.

Comparative Examples 1 to 3 A powder coating was applied in the same manner as in Example 1, except that the graft-modified polyester (CP-1) was replaced with the comparative polyesters (P-1) to (P-3), respectively. Obtained.

Comparative Example 4 A powder coating was obtained in the same manner as in Example 7 except that the graft-modified polyester (GP-7) was replaced with the control polyester (P-4).90 Comparative Example 516 Graft-modified polyester Compare (GP-1) vs. 4 for black
A powder coating material was obtained in the same manner as in Example 1 except that the polyesters (P-5) and (P-6) were used.

Comparative Example 7 A powder coating was obtained in the same manner as in Example 8, except for the holes, except that the graft-modified polyester (GP-1) was replaced with a comparative polyester (p-i).

Comparative Example 8゜The graft modified polyester (GP-1) was replaced with the base polyester for comparison (R-1), except for the holes of Example 1.
A powder coating was obtained in the same manner as above.

Each of the powder coatings of Examples 1 to 8 and Comparative Examples 1 to 8 was applied to a 0.8μ thick zinc phosphate treated steel plate by electrostatic spraying to a film thickness of 50 to 60μ, and then heated at 200°C. Baked for 20 minutes to create a test piece and evaluate the coating performance. The results are summarized in Table-1.

(Effects of the Invention) As is clear from the examples, the present invention provides a powder coating that not only has mechanical strength but also has excellent pigment dispersibility and forms a coating film with excellent coating appearance and surface hardness. /IJ ester resin is obtained.

Claims (1)

[Claims] 0.0% nitrogen atom-containing vinyl monomer is added to the polyester resin.
1. A method for producing a graft-modified polyester resin for powder coatings, characterized by carrying out a graft reaction of 01 to 5.0% by weight.