JPH02235969A - Resin composition for thermosetting powder coating material - Google Patents

Abstract

PURPOSE:To prepare a resin compsn. which gives a curable coating film excel lent in the resistance to solvent and weathering by blending a fluoroolefin copoly mer contg. glycidyl groups with a curing agent reactive with said glycidyl groups. CONSTITUTION:A fluoroolefin copolymer contg. glycidyl groups and having a number average MW of 1,000 to 100,000 and softening point measured by the ring and ball method of 50 to 150 deg.C is compounded with a curing agent reactive with said glycidyl groups. Said fluoroolefin copolymer is obtd. by copolymerizing 15 to 70wt.% fluoroolefin, 5 to 40wt.% monomer contg. a glycidyl group, and 5 to 80wt.% other copolymerizable monomer in such a wt. ratio that the total of the three components is 100wt.%. Said curing agent includes a compd. contg. at least two carboxyl group, and a polybasic acid or anhydride thereof is esp. pref.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a new and useful resin composition for thermosetting powder coatings. More specifically, the present invention comprises a glycidyl group-containing fluoroolefin copolymer as a paste resin component and a glycidyl group-reactive compound as a curing agent component, or a glycidyl group-containing A so-called fluoroolefin copolymer, a glycidyl group-reactive curing agent, and a curing catalyst.
The present invention relates to a resin composition for fluororesin-based powder coatings.

[Conventional technology]

As this type of fluororesin-based resin for powder coatings, there is a thermoplastic type resin whose main component is vinylidene fluoride.

Fluororesins (fluoroolefin copolymers) are widely used due to their good chemical resistance, heat resistance, abrasion resistance, non-stick properties, and weather resistance. However, because of its high melting point, special equipment is required for crushing it, and it is also indispensable to melt and bake it at daytime temperature, so it is rarely used as a powder coating. The current situation is that this has not been done.

Furthermore, in Japanese Patent Application Laid-Open No. 59-120661, (
・Although a technique has been disclosed for modifying a vinyl copolymer resin by using a resin obtained by copolymerizing a monomer having a {-)fluoroalkyl group as an additive, such additive resins and As such, there are limits to the amount added due to compatibility and, in particular, resistance to prosodication when used in powder coatings.

Furthermore, acrylic powder coatings, which are thermosetting powder coatings, are widely used for their excellent weather resistance, stain resistance, and appearance, or for applications that require long-term weather resistance. Therefore, it is desired to put into practical use a thermosetting, highly weather resistant powder coating that is easy to handle using conventional manufacturing methods.

[Problem to be solved by the invention]

Therefore, in view of the various shortcomings in the prior art described above, the present inventors developed a fluororesin system that can be cured under commonly used curing conditions, that is, under the same curing conditions as general-purpose powder coatings. As a result of intensive research aimed at obtaining a powder coating, we found that it has a specific molecular weight and softening point,
Moreover, the composition is a combination of a fluoroolefin copolymer containing a glycidyl group as a reactive group (functional group) and a curing agent that can react with the glycysol group.
Since it has excellent curability, it has been found that it can provide a cured coating film that not only has excellent solvent resistance but also has extremely excellent weather resistance, and has completed the present invention.

[Failure to solve the problem]

That is, in the present invention, as essential components, the softening point measured by the ring and ball method is 60 to 150°C, and the number average molecular weight is i.
, ooo to 100,000 and comprising a glycidyl group-containing fluoroolefin copolymer (A) and a glycidyl group-reactive curing agent (B), or
Such a fluoroolefin copolymer (A), a glycidyl group-reactive curing agent (B), and a curing catalyst for promoting the crosslinking reaction between the copolymer (A) and the curing agent (B).
C) A resin composition for powder coating is provided.

Here, the above-mentioned fluoroolefin copolymer (
Examples of A) include vinyl butylene, vinylidene butylene, trifluoroethylene, tetrafluoroethylene, promotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, or the carbon of a (per)fluoroalkyl group. Contains a fluoroolefin unit as an essential constituent unit, such as (.so-)fluoroalkyl trifluorovinyl ether having a number of 1 to 18, and also has a reactive group (functional group) such as a hydroxyl group or a glycidyl group in the side chain. In this sense, the fluoroolefin copolymer (g) is a fluoroolefin as listed above [hereinafter referred to as one reaction component (a-1)]. shall be. ] and as listed below, respectively.
A monomer containing a glycidinole group [hereinafter referred to as (a-
2) One reaction component. ] and these fluoroolefins (a-1) and glycidyl group-containing monomers (&
-2) and other monomers copolymerizable [hereinafter referred to as (a3
) as one reaction component. ] is preferable.

Typical examples of the glycidyl group-containing monomer (a-2) include glycidyl vinyl ether, (β-
Examples include methyl)glycidyl acrylate, (β-methyl)glycidyl methacrylate, and allylglycidyl ether, but from the viewpoint of copolymerizability, it is desirable to use vinyl ethers. On the other hand, acrylic materials include various fluoroolefins (
Since copolymerizability with a-1) is insufficient, the amount used should be kept within a range that does not reduce the polymerization rate of the target copolymer (A).

Furthermore, fluoroolefin/(a-1) as listed above
Typical examples of other monomers (a-3) copolymerizable with the glycidyl group-containing monomer (a-2) include methyl vinyl ether, ethyl vinyl ether, n-globin vinyl ether, isofurohir vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert
- Alkyl vinyl ethers such as butyl vinyl ether, n-bentyl vinyl, n-hexyl vinyl ether, n-octyl vinyl ether, <ld2-ethylhexyl vinyl ether; Classes: Chiralkyl vinyl ethers such as ben-zorvinyl ether or phenethyl vinyl ether:
2,2,3.3-tetrafluoropropylene vinyl ether, 2.2,3,3,4.4,5.5-octafluorobentyl vinyl ether, 2,2.3,3,4,4,
5,5,6,6,7,7,8,8.9,9-hexadecafluorononyl vinyl ether, perfluoromethyl vinyl ether, perfluoroethyl vinyl ether i
+ - 7 Fluoroglobin vinyl ether, Noyafluorooctyl vinyl ether 4L< is fluoroalkyl vinyl ethers such as perfluorocyclohexyl vinyl ether; Other is vinyl acetate, vinyl propionate, vinyl n-monobutyrate, vinyl isobutyrate , vinyl pivalate, vinyl caproate, hinyl versatate,
Vinyl laurate, vinyl stearate, vinyl benzoate, p-tert-butyl vinyl benzoate, salicylic acid vinyl esters such as vinyl hacyclohexanecarboxylate.
x-7b: In addition, ethylene, globylene, vinyl chloride, vinylidene chloride, (meth)acrylonitrile or various (meth)acrylic acid esters can also be used.

Among the other copolymerizable monomers (a-3), alkyl vinyl ethers; It is desirable to use at least one member selected from the group consisting of cycloalkyl vinyl ethers and caldic acid vinyl esters. From the side,
cycloalkyl vinyl ethers, or vinyl cyclohexanecarboxylate, vinyl acetate, vinyl benzoate or vinyl p-tert-butylbenzoate, or caru-bonded to a tertiary carbon atom? It is desirable to use at least one member selected from the group consisting of vinyl esters of aliphatic carboxylic acids of 05 to C18 having a xyl group.

In order to obtain the desired fluoroolefin copolymer from the various search components listed above, 15 to 70% by weight of the fluoroolefin (a-1) and the glycidyl group-containing monomer (a- 2) and 5 to 80% by weight of the other copolymerizable monomer (a-3), preferably 20 to 60% by weight of (a-1), ( a-2) 1
0 to 40% by weight of M and 10 to 70% by weight of (a-3) may be copolymerized such that the total amount of all these reaction components is 100% by weight.

If the amount of fluoroolefin (a-1) used is less than 15% by weight, the weather resistance will be insufficient, while if it exceeds 70% by weight, the gloss of the coating will not be low, so Moreover, if the amount of the glycidyl group-containing monomer (a-2) used is less than 5% by weight, the curability will inevitably be low, and the resulting coating film will therefore have insufficient solvent resistance. On the other hand, if it exceeds 40% by weight, the amount of curing agent (B) used will increase, which will inevitably lead to a decrease in weather resistance, which is undesirable. If the amount of monomer (a3) used is less than 5% by weight, the gloss of the coating film tends to be insufficient, while if it exceeds 80% by weight, the weather resistance inevitably decreases. Neither is preferable.

In order to prepare the fluoroolefin copolymer (A), known methods such as bulk polymerization, solution (pressure) polymerization, suspension polymerization 1 or emulsion polymerization may be carried out in the presence of a radical polymerization initiator. Depending on the method, it may be carried out in a batch, semi-continuous or continuous manner.

As the above-mentioned radical polymerization initiator, acetyl t4-
Noah silver oxides such as oxide or penzoylno-e-oxide; ketone peroxides such as methyl ethyl ketone peroxide or cyclohexanone oxide; hydrogen peroxide or t
Hydroperoxides such as ert-butyl hydroperoxide; dialkyls such as tert-butyl peroxide or dicumyl oxide! +-Oxides: Alkyl A'-oxyesters such as tert-butylperoxyacetate or tert-butylperoxybiparate; or persulfates such as potassium persulfate or ammonium persulfate; al or azobisinbutyro Typical examples include azo compounds such as nitrile and azobisisovaleronitrile, but if necessary, these may be combined with an inorganic reducing agent such as sodium bisulfite or sodium birosulfite, or cobalt naphthenate or dimethylaniline. It may also be used in combination with an organic reducing agent such as.

As a copolymerization reaction method, among the various methods listed above, the solution polymerization method is the simplest. Typical solvents used in this process include toluene, xylene,
Hydrocarbons such as chlorhexane, n-hexane or octane; esters such as methyl acetate, ethyl acetate or butyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone; amides such as dimethylformamide or dimethylacetamide. or alcoholic solvents such as methanol, ethanol, isopropanol, n-butanol, imptanol, sec-butanol or ethylene glycol monoalkyl ether, or mixtures thereof.

However, when carrying out such a copolymerization reaction, various chain transfer agents such as lauryl mer-butane, octyl mer-butane, 2-mercaptoethanol, or α-methylstyrene dimer are used as molecular weight regulators. can also be used.

When carrying out the copolymerization reaction, a temperature within the range of -20°C to 150°C is appropriate, and the temperature is approximately 10°C.
A reaction pressure of 0 K9/cm2 or less is suitable.

The fluoroolefin copolymer obtained in this way (
As a method for removing water or a solvent as a medium from the dispersion solution in A), any of the known methods can be used, and in particular, a method of heating and distilling under reduced pressure is recommended.

The number average molecular weight of the obtained copolymer (A) is usually in the range of i,ooo to 100,000, preferably 3,000 to 20,000. Engineering? The xy equivalent is usually 270-2
,000, preferably in the range from 350 to 1,500.

Furthermore, the softening point of the fluoroolefin copolymer (A) is usually 60 to 150°C, preferably 80 to 150°C.
A temperature within the range of 130°C is suitable.

If this softening point is less than 60°C, problems tend to appear in the blocking resistance of the powder coating;
If the temperature is too high, exceeding 0°C, the smoothness of the coating film will inevitably deteriorate, which is not preferable.

Next, representative examples of the glycidyl group-reactive curing agent (B), the curing agent having reactivity with the glycidyl group in the fluoroolefin copolymer (A), and those having at least two carpoxyl groups. Examples include compounds, among which it is particularly desirable to use polybasic acid compounds or their acid anhydride compounds.

First, typical examples of such polybasic acid compounds include acrylic resins having two or more carboxyl groups in one molecule, polyester resins having two or more carboxyl groups in one molecule, and c) adipic acid. , aliphatic dibasic acids such as sebacic acid, azelaic acid, decanoic acid, hexadeca/diacid, icosaniic acid or tetraicosaniic acid; or aromatic dibasic acids such as isophthalic acid; Examples include alicyclic dibasic acids such as hydrophthalic acid or tetrahydrophthalic acid; further tribasic acids such as trimellitic acid; and, of course, those having the general formula HOOC -{CF 2}
-Ya-fluoronibasic acid represented by --COOH [I] can also be used.

Typical examples of the polybasic acid anhydride compounds mentioned above include acrylic resins or polyester resins having two or more acid anhydride groups in one molecule, or trimellitic anhydride or pyroanhydride. Examples include mellitic acid.

Of course, the various compounds listed above can be used alone or in combination of two or more, but among these various compounds, from the viewpoint of blocking resistance and various physical properties, aliphatic dibasic It is desirable to use acids, especially linear dibasic acids, and from the viewpoint of weather resistance, it is desirable to use per-7 fluoronibasic acids.

r1 et al.) The amount of the glycidyl group-reactive curing agent (B) used is 0.5 to 0.5 to the (β-methyl)glycidyl group present in the glycidyl group-containing fluoroolefin copolymer. It is appropriate to have a ratio of 15 times equivalent, and it is desirable to blend the amount within this range.

Furthermore, as a representative example of the above-mentioned curing catalyst (C), triphenylphosphine may be used. Various ho/l. Examples include 7ynes and various imidazoles such as 2-methylimidazole.

The thus obtained resin composition for powder coating of the present invention may further contain known pigments, various resins, fluidity regulators, antioxidants, ultraviolet absorbers, silane coupling agents, etc., as necessary. Of course, various conventional additives can be added.

The composition of the present invention can be prepared by mixing each of the above-mentioned components with a mixer such as a hot roll or a co-kneader.
It is obtained by melt-kneading at a temperature of about 0 to 150°C and then pulverizing.

〔Example〕

Next, the present invention will be explained in detail with reference to Reference Examples, Examples, and Comparative Examples. In the following, all parts and percentages are based on weight unless otherwise noted.

Reference Examples 1 to 7 [Preparation example of fluoroolefin copolymer (A)] In a stainless steel pressure-resistant container with an internal volume of 1 liter, 4001 of methyl isobutyl ketone and [ as shown in Table 1] were added. Perbutyl PV J [peroxide-based radical polymerization initiator manufactured by NOF Corporation] and bis(1,2,
2.6.6-pentamethyl-4-biveridinyl) sebacate, ethyl vinyl ether (EVE), cyclohexyvinyl ether (CHVE), glycidyl vinyl ether (GVE), glycidyl methacrylate (GMA), glycidyl acrylate (GA) Vinyl ester of C, aliphatic caldenic acid having a caldexyl group bonded to a tertiary carbon atom, manufactured by Shell, Netherlands; hereinafter abbreviated as YV-9.]
, vinyl benzoate (VBZ) or p(l8) tert-butyl vinyl benzoate (VPTBZ), cooled to -70°C in a dry ice/methanol bath, and replaced the air in the pressure vessel by blowing in nitrogen gas. did.

Next, the liquefied and collected chlortrifluoroethylene (
CTFE) or hexafluoropropylene (RF
P) at the weight ratio shown in the same table and sealed in a tube. On the other hand, when using tetrafluoroethylene (TFE), a pressure-resistant container with a valve was used, and each raw material was charged in the same manner as described above. After the preparation, TFE of and was sealed under pressure from a TFE pump, and then the valve was closed and weighed.

Thereafter, each of these pressure-resistant containers was placed in a rotary thermostatic water bath heated to 60°C, and after a 16-hour reaction, the contents were taken out, and the solvent was added under reduced pressure and heating conditions. Then, the volatile components were distilled off to obtain the desired copolymers for each food.

When each characteristic value was measured for each fluoroolefin copolymer (A), the results shown in the table were obtained.

Examples 1 to 9 and Comparative Example 1 Each fluoroolefin copolymer (A) obtained in each reference example was mixed with a curing agent (B) and a filler in the weight ratios shown in Table 2. Mixing or hardening agent (B
), a curing catalyst (C), and a filler were mixed, cooled, pulverized, and then classified using a 150-mesh wire mesh to obtain a powder coating.

Next, each powder coating was applied electrostatically to a Denderite-treated steel plate with a thickness of 08 to give a film thickness of 60 to 70 microns after baking, and baked at 180°C for 20 minutes. A cured coating film was obtained.

In addition, as Comparative Example 1, commercially available acrylic powder paint,
1,? , a conventional powder coating that is fluorine-free and contains glycisol groups was used.

When various physical properties of each coating film were evaluated, the results shown in the table were obtained.

Note that the procedures and criteria for evaluating each physical property are as shown below.

Smoothness: determined by visual inspection Gloss: - Compliant with JIS K5400 Sections 6 and 7 Erichsen: Compliant with JIS Z-2247 The larger the Erichsen value, the better the flexibility. .

Broken kink resistance... 4 Qur about powder coating 157
nφ test MIfK [Jf2L, 20y-/CTn2 was applied and the sample was left at 35℃ for 240 hours. If the sample returned to its original powder state after that, it was considered "good" and blocking was observed. If it was, it was marked as ``not disgraced.''

Weather resistance: It is expressed as the gloss retention rate after 1,000 hours on a Sunshine Weatherometer, and the higher the value, the better the weather resistance.

, -9/' [Effects of the Invention] As is clear from the results in Table 2, the resin composition for powder coatings of the present invention has weather resistance that far exceeds that of conventional powder coatings, and It can be seen that the balance K of various physical properties is also excellent.

Claims (1)

[Claims] 1. (A) Number average molecular weight is 1,000 to 100,000
and the softening point according to the ring and ball method is 60 to 150°C.
A fluoroolefin copolymer having a glycidyl group,
(B) a curing agent that is reactive with this glycidyl group,
A resin composition for a thermosetting powder coating, comprising the following as an essential component. 2. (A) Number average molecular weight is 1,000 to 100,000
and the softening point according to the ring and ball method is 60 to 150°C.
A fluoroolefin copolymer having a glycidyl group,
(B) a curing agent that is reactive with this glycidyl group;
C) The above glycidyl group-containing fluoroolefin copolymer (A) and the above glycidyl group-reactive curing agent (B)
A resin composition for a thermosetting powder coating, comprising as an essential component a curing catalyst for promoting a crosslinking reaction with a thermosetting powder coating. 3. The glycidyl group-containing fluoroolefin copolymer (A) has 15 to 70 of the fluoroolefin (a-1).
5% by weight of the monomer (a-2) having a glycidyl group
~40% by weight, and the above-mentioned fluoroolefin (a-1
) and 5 to 80% by weight of the other monomer (a-3) copolymerizable with the glycidyl group-containing monomer (a-2), these (a-1), (a-2) The resin composition for a thermosetting powder coating according to claim 1 or 2, which is obtained by copolymerizing the monomers (a-3) and (a-3) such that the total amount is 100% by weight. . 4. Claim 1, wherein the glycidyl group-reactive curing agent (B) is a compound having at least two carboxyl groups.
or the resin composition for thermosetting powder coating according to 2. 5. The resin composition for a thermosetting powder coating according to claim 1, 2 or 4, wherein the glycidyl group-reactive curing agent (B) is a long-chain aliphatic linear dibasic acid. 6. The glycidyl group-reactive curing agent (B) has the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ [I] [However, n in the formula shall be an integer from 1 to 24. ] The resin composition for thermosetting powder coating according to claim 1, 2 or 4, which is a compound represented by the following.