JPH0477543A - Thermosetting resin composition - Google Patents

Abstract

PURPOSE:To provide a thermosetting resin composition containing an OH- containing fluoroolefin copolymer, a vinyl copolymer containing a specific reactive polar group and curing agent, having excellent storage stability, recoatability and weather resistance and suitable especially for powder coating. CONSTITUTION:The objective thermosetting resin composition is composed of (A) an OH-containing fluoroolefin copolymer composed of a fluoroolefin, an OH-containing monomer (preferbly vinyl ether monomer) and a copolymerizable monomer and having a number-average molecular weight of 1,000-100,000 and a softening point of 60-150 deg.C, (B) a vinyl copolymer having at least one kind of group selected from OH, acid group and glycidyl group, preferably a polymer having a softening point of 40-150 deg.C and produced by using a cyclohexyl (meth)acrylate and an alkyl (meth)acrylate having a 1-4C alkyl group (the sum of the monomers is >=50wt.% or the amount of either one of the monomers is >=30wt.%) and (C) a curing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a new and useful thermosetting resin composition. More specifically, the present invention relates to a specific reactive polar curable resin composition.

[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 excellent chemical resistance, heat resistance, abrasion resistance, non-stick properties, and weather resistance. Due to its high melting point, special equipment is required to crush it, and it also requires melting and baking at high temperatures, so it is rarely used as a powder coating. , is the current situation.

Furthermore, in Japanese Patent Application Laid-Open No. 59-120661, (
B) A thermosetting resin composition modified using a vinyl copolymer obtained using a fluoroalkyl group-containing vinyl monomer as an additive has been disclosed; When used as a paint, there is a limit to the amount added from the viewpoint of anti-blocking properties.

Further, JP-A-1-103670 also discloses a technology regarding a thermosetting resin composition for a fluorine-containing powder coating, and it is said that weather resistance etc. are significantly improved.

However, in actual painting, practical problems remain in terms of repaintability (recoatability) and stain resistance over time.

[Secret B to be Solved by the Invention] As described above, as long as the above-mentioned conventional techniques are followed, the material has excellent weather resistance, anti-blocking properties, repaintability, and stain resistance over time. It is difficult to obtain extremely useful thermosetting resin compositions.

Therefore, the problem to be solved by the present invention is to provide a practical thermosetting resin composition that is particularly excellent in repaintability and stain resistance over time. .

[Means for Solving the Problems] Therefore, in view of the existence of various drawbacks in the prior art as described above, the present inventors set their sights on the problems to be solved by the invention as described above, With the aim of obtaining a fluororesin powder coating that can be cured under commonly used curing conditions, i.e., under the same curing conditions as general-purpose powder coatings, we have conducted extensive research and developed a specific A fluoroolefin copolymer that has a molecular weight and a softening point and also has a hydroxyl group as a reactive polar group (functional group), and a specific hydroxyl group, acid group, and glycidyl group that are compatible with the copolymer. A composition comprising a combination of a vinyl copolymer having at least one functional group selected from the group consisting of a curing agent capable of reacting with such hydroxyl group, acid group, or glycidyl group improves the storage stability of the paint It has excellent repaintability, excellent stain resistance after long-term exposure, and it also provides a cured coating with extremely excellent weather resistance. After discovering something, we have completed the present invention.

That is, the present invention uses, as essential components, a fluoroolefin copolymer (A) having a hydroxyl group, and a vinyl copolymer (B) having a hydroxyl group, an acid group, and/or a glycidyl group.
) and a curing agent (C), which is useful for paints, especially powder paints.

Here, the above-mentioned fluoroolefin copolymer (
Examples of A) include vinyl butylene, vinylidene butylene, trifluoroethylene, tetrafluoroethylene, promotrifluoroethylene, chlorotrifluoroethylene, pentafluoropropylene, hexafluoropropylene, and the carbon of a mataha(bar)fluoroalkyl group. Examples include those containing a fluoroolefin unit as an essential structural unit, such as (bar)fluoroalkyl trifluorovinyl ether having a number of 1 to 18, and further having a hydroxyl group in the side chain, and the fluoroolefin copolymer (A) is, for example, the following fluoroolefin c as shown above, and this is used as the -reaction component (a-1). ] and a hydroxyl group-containing monomer (hereinafter referred to as :tL(a-2)), respectively, as shown below. ] and another monomer copolymerizable with these fluoroolefins (a-1) and the hydroxyl group-containing monomer (a-2) [hereinafter, this will be referred to as (a-3) -reaction component. ]
It is prepared by copolymerizing the following.

Representative examples of the hydroxyl group-containing monomer (a-2) used in preparing the desired fluoroolefin copolymer (A) by this method include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyethyl vinyl ether, l-hydroxymethyl-4-vinyloxymethyl Cyclohexane, 2
-Hydroxyethyl ether, 3-hydroxypropyl allyl ether, 4-hydroxybutyl allyl ether, 2-hydroxyethyl acrylate or 2-
Examples include hydroxyethyl methacrylate.

Among the hydroxyl group-containing monomers (a-2), from the viewpoint of copolymerizability, vinyl ether-based monomers are most desirable;
On the other hand, since acrylic materials have insufficient copolymerizability with the above-mentioned fluoroolefin (a-1), the amount used should be within a range that does not reduce the polymerization rate of the target copolymer (A). should be stopped.

Furthermore, a fluoroolefin (a-1) as listed above
Typical examples of other monomers (a-3) copolymerizable with the hydroxyl group-containing monomer (a-2) include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, and n-butyl vinyl ether. , alkyl vinyl ethers such as isobutyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl, n-hexyl vinyl ether, n-octyl vinyl ether or 2-ethylhexyl vinyl ether; cycloalkyl vinyl ethers such as cyclopentyl vinyl ether, cyclohexyl vinyl ether or methylcyclohexyl vinyl ether; Aralkyl vinyl ethers such as hensyl vinyl ether or phenethyl vinyl ether: 2,2
, 3.3-tetrafluoropropyl vinyl ether, 2
,2,3,3,44.5.5-,tphtafluoropentyl 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, perfluoropropyl vinyl ether, perfluorooctyl vinyl ether or perfluorocyclohexyl vinyl ether. ) Fluoroalkyl vinyl ethers; or vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl isobutyrate, vinyl piperate, vinyl caproate, vinyl persate, vinyl laurate, vinyl stearate, fa-hinyl benzoate, p- te
Examples include carboxylic acid vinyl esters such as vinyl rt-butylbenzoate, vinyl salicylate, and vinyl cyclohexanecarboxylate; further examples include ethylene, propylene, vinyl chloride, vinylidene chloride, (meth)acrylonitrile, and various (meth)acrylics. Acid esters and the like can also be used.

Among the other copolymerizable monomers (a-3), alkyl vinyl ethers are preferred from the viewpoint of improving the polymerization rate during the preparation of the target copolymer (A) and improving the weather resistance of the coating film. ; It is preferable to use at least one member selected from the group consisting of cycloalkyl vinyl ethers and carboxylic acid vinyl esters, and particularly in terms of storage stability (blocking resistance) of the resulting paint and hardness of the coating film. , cycloalkyl vinyl ethers, or vinyl cyclohexanecarboxylate, vinyl acetate, vinyl benzoate or vinyl p-tert-butylbenzoate, or aliphatic carboxylic acids from C1 to C11 having a carboxyl group bonded to a tertiary carbon atom. It is desirable to use at least one selected from the group consisting of vinyl esters.

In order to obtain the desired fluoroolefin copolymer (A) from the various reaction components listed above, 15 to 703II% of the fluoroolefin (a-1) and the hydroxyl group-containing monomer (a-2) are added. and 5 to 84 weight% of the other copolymerizable monomer (a-3,-), preferably 20 to 60 weight% of (a-1), (a 2 to 25% by weight of -2) and 10 to 77% 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 155% by weight, the weather resistance will be insufficient;
If it exceeds % by weight, the gloss of the coating film will not be low, which is not preferable, and if the hydroxyl group-containing monomer (
If the amount of a-2) used is less than 1% by weight, the curability will inevitably be low, resulting in insufficient solvent resistance of the resulting coating film.On the other hand, if the amount used exceeds 30% by weight, the curing agent (C)
Both of these are undesirable because they increase the amount of copolymerizable monomer (a-3), which inevitably leads to a decrease in weather resistance. If the amount is less than 84% by weight, the gloss of the coating film tends to be insufficient, while if it exceeds 84% by weight, the weather resistance inevitably decreases, so both are not preferred.

The fluoroolefin copolymer (A) can also be prepared by a known method such as bulk polymerization, solution (pressure) polymerization, suspension polymerization, or emulsion polymerization in the presence of a radical polymerization initiator. It may be carried out in a batchwise, semi-continuous or continuous manner.

Examples of the above-mentioned radical polymerization initiators include diacyl peroxides such as acetyl peroxide or benzoyl peroxide; ketone peroxides such as methyl ethyl ketone peroxide or cyclohexanone peroxide; hydrogen peroxide or tert
- hydroperoxides such as butyl hydroperoxide; dialkyl peroxides such as tert-butyl peroxide or dicumyl peroxide; alkyl peroxides such as tert-butyl peroxyacetate or tert-butyl peroxypivalate; Typical examples include oxyesters; persulfates such as potassium persulfate or ammonium persulfate; and azo compounds such as azobisisobutyronitrile and azobisisovaleronitrile; It may also be used in combination with an inorganic reducing agent such as sodium bisulfite or sodium pyrosulfite, or an organic reducing agent such as cobalt naphthenate or dimethylaniline.

As a copolymerization reaction method, among the various methods mentioned above, the solution polymerization method is the simplest. Typical solvents used in this case include hydrocarbons such as toluene, xylene, cyclohexane, n-hexane, or octane; esters such as methyl acetate, ethyl acetate, or butyl acetate; acetone, methyl ethyl ketone, and methyl isobutyl. Ketones such as ketones or cyclohexanone; amides such as dimethylformamide or dimethylacetamide; or alcoholic solvents such as methanol, ethanol, isopropanol, n-butanol, isobutanol, 5ec-butanol or ethylene glycol monoalkyl ether; There are mixtures of these.

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

When carrying out the copolymerization reaction, a temperature within the range of -20°C to 150°C is appropriate, and approximately 100°C.
A reaction pressure of less than 1 kg/cm" is suitable.

Depending on the reaction conditions, the hydroxyl group-containing monomer (a-2
) often leads to gelation when copolymerized with fluoroolefin (a-1), but in order to prevent such gelation, it is necessary to use so-called tertiary amines, solid bases, etc. It is desirable to carry out the copolymerization reaction in the presence of a basic substance.

The fluoroolefin copolymer obtained in this way (
As a method for removing water or a solvent as a medium from the dispersion or 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 1,000 to 100,000, preferably 3,000 to 20,000, and the hydroxyl group of the copolymer (A) is The value is usually 5 to 200
, preferably within the range of 10 to 100.

Furthermore, the softening point of the fluoroolefin copolymer (A) is usually 60 to 150''C1, preferably 80
A range of 130°C to 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, the above-mentioned hydroxyl-reactive curing agent (C), that is,
Typical examples of curing agents that are reactive with the hydroxyl groups in the fluoroolefin copolymer (A) include aminoplast, pronokpolyisonoir mono-compound, or polybasic acid (
Anhydrous #yJ);! , etc., and it is of course possible to use these various curing agents in combination.

Among these, representative examples of aminoplasts include amino group-containing compound components such as melamine, urea, acetoguanamine, Henzuguanamine, steroguanamine, or spiroguanamine, and aldehyde compound components such as formaldehyde, paraformaldehyde, acetaldehyde, or glyoxal. Examples include condensates obtained by reacting with known and commonly used methods, and those obtained by etherifying each of these condensates with alcohols, but even those normally used for powder coatings. Of course, any of them can be used.

In addition, block polyisocyanate compounds include various polyisocyanate compounds having at least two isocyanate groups in the molecule.
It refers to a compound obtained by blocking with a vine-forming agent, and typical examples of polyisocyanate compounds include aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate; hydrogenated xylylene diisocyanate or Cycloaliphatic diisocyanates (cycloaliphatic diisocyanates) such as isophorone diisocyanate; or organic diisocyanate compounds such as aromatic diisocyanates such as tolylene diisocyanate or 4,4'-diphenylmethane diisocyanate; or various organic diisocyanate compounds thereof; Examples include adducts with polyhydric alcohols, low molecular weight polyester resins, water, etc., as well as polymers and isocyanate biuret compounds of the above-mentioned organic diisocyanate compounds, among others, isophorone diisocyanate (IPD).
I) or adducts of IPDI and various polyol compounds, which are so-called isophorone diisocyanate-based polyisocyanates blocked with ε-caprolactam, are preferably used.

It goes without saying that compounds that regenerate isocyanate groups by heat, such as urentodione bonds, can also be used.

Further, as a representative example of the polybasic acid curing agent mentioned above, -
Examples include acrylic resins having two or more carboxyl groups in the molecule, polyester resins having two or more carboxyl groups in the molecule, or pyromellitic acid.On the other hand, polybasic acid anhydride curing agents Typical examples include acrylic resins having two or more acid anhydride groups in the molecule, trimellitic anhydride, pyromellitic anhydride, and the like.

Among the various curing agent (C) component compounds listed above, it is desirable to use block polyisocyanate compounds, especially from the viewpoint of physical properties and storage stability (pronging resistance).

Next, particularly preferable vinyl copolymers (B) having a hydroxyl group, an acid group and/or a glycidyl group have a number average molecular weight of 1,000 to 100,000, and have a softening property measured by the ring and ball method. Score 40-15
0° C., preferably a number average molecular weight of 2,000 to 10,000, and a softening point of 7.
It is within the range of 0 to 130°C.

Particularly typical monomers used in preparing the vinyl copolymer (B) include: α,β-monoethylenically unsaturated monomers having hydroxyl groups; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-
Hydroxypropyl (meth)azilylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate or 4-hydroxybutyl (
meth)acrylate, etc., and the α,β-monoethylenically unsaturated monomer having an acid group includes (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid or maleic anhydride, etc. Monomethyl maleate, monoethyl fumarate, mono-n-butyl itaconate, etc., and α,β-containing glycidyl groups.
As the monoethylenically unsaturated monomer, glycidyl (meth)acrylate or β-methylglycidyl (meth)
Such as acrylate.

In addition to monomers having these specific reactive polar groups (functional groups), it is of course possible to use monomers that are copolymerizable with these various functional group-containing monomers. Therefore, to cite only typical examples of such copolymerizable monomers, styrene,
CI' = Cz4 (meth)acrylic acid ester type or vinyl ester type, etc., and from the viewpoint of compatibility with the fluoroolefin copolymer (A), C1 to C4
It is particularly desirable to use alkyl (meth)acrylates or cyclohexyl (meth)acrylates having an alkyl group.

The amount of each functional group (functional group content) in the vinyl copolymer (B) is 0 to 150 ■KOH/g, preferably 1
A range of 0 to 130 ■Kon/g is appropriate, and the acid group content is expressed as an acid value of 0 to 150 ■Kon/g.
g, preferably within the range of lO to 100 ■KOH/g, and the glycidyl group content, expressed as epoxy equivalent, is preferably within the range of 0 to 2.000 g/eq, preferably 400 to 150°. The inside is appropriate.

Furthermore, the blending ratio of the above-mentioned fluoroolefin copolymer (A) and the vinyl copolymer (B) is (A)/(B)=9515 to 20/80, preferably 90/80 on a weight basis. /10 to 30/70.

If the amount of vinyl copolymer (B) used is small, repaintability will inevitably deteriorate, while if it is used in a large amount, weather resistance will inevitably deteriorate. , both cases are unfavorable.

A curing agent capable of reacting with the glycidyl group and/or acid group in the vinyl copolymer (B) is replaced with the above-mentioned aminoplast or bronze capable of reacting with the hydroxyl group in the above-mentioned fluoroolefin copolymer (A). Of course, in addition to so-called main curing agents such as polyisocyanate compounds or polybasic acids (anhydrides), they can also be used as so-called auxiliary curing agents. A compound or a glycidyl group-containing compound may be used.

The thermosetting resin composition of the present invention thus obtained includes:
In addition, pigments, various resins, fluidity regulators,
Of course, various known and commonly used additives such as antioxidants, ultraviolet absorbers, and silane coupling agents can also be incorporated.

The composition of the present invention is particularly suitable for use as a powder coating, and in that case, each component as listed above is mixed with a kneader such as a hot roll or a co-kneader to a It may be prepared by melt-kneading at a temperature of about 150°C and then pulverizing.

〔Example〕

Next, the present invention will be explained by reference examples, examples, and comparative examples.
Although the layers will be specifically explained, all parts and percentages hereinafter are based on weight unless otherwise specified.

Reference Examples 1 to 3 (Example of Preparation of Fluoroolefin Copolymer (A)) In a stainless steel pressure-resistant container with an internal volume of 11, 400 g of methyl isobutyl ketone and
8 g of J (peroxide-based radical polymerization initiator manufactured by NOF Corporation) and 5 g of bis(1,2,2,6,6pentamethyl-4-piperidinyl) sebacate as shown in Table 1. Ethyl vinyl ether (EVE),
4-Hydroxybutyl vinyl ether ()IBVE)
, vinyl benzoate (VBZ) or vinyl p-tert-butylbenzoate (VPTBZ) was charged and cooled to -70°C in a dry ice/methanol bath, and nitrogen gas was blown to replace the air in the pressure vessel.

Next, the liquefied and collected chlortrifluoroethylene (C
TFE) or hexafluoropropylene (RFP)
were charged in the weight ratio shown in the same table, sealed in a tube, and then the valve was closed and weighed.

After that, each of these pressure-resistant containers was placed in a rotary constant-temperature water bath heated to 60°C and reacted for 16 hours, then the contents were taken out and the solvent and volatiles were further removed under reduced pressure and heating conditions. The fraction was distilled off to obtain various desired copolymers.

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

Reference Example 4 [Preparation example of vinyl copolymer (B)] 50 parts of methyl methacrylate, 20 parts of cyclohexyl methacrylate and 3 parts of 2-hydroxyethyl methacrylate
A mixture consisting of 0 parts of azobisisobutyronitrile and 5 parts of azobisisobutyronitrile was dropped under normal pressure into a reaction vessel in which 100 parts of xylene had been charged in advance, and a polymerization reaction was carried out while refluxing. At 90°C, add 0.3 part of azobisisobutyronitrile and continue the reaction by keeping at the same temperature for 10 hours to remove xylene, resulting in a number average molecular weight of 3.000. The desired copolymer was obtained.

Reference Examples 6 to 10 (same as above) Various desired copolymers were obtained in the same manner as in Reference Example 4, except that the monomer usage ratios were changed to those shown in Table 2.

/ Q-” Examples 1 to 9 and Comparative Examples 1 to 3 The fluoroolefin copolymer (An and vinyl copolymer (B) obtained in each reference example were treated as shown in Table 3. The curing agent (C), filler, and additives were uniformly mixed in a mixing ratio using a "Henschel mixer" (a dry blender manufactured by Mitsui Kakoki Co., Ltd.), and heated at a temperature of 80 to 120°C. Under the conditions, "Busco kneader"
(The mixture was melt-kneaded using an extrusion kneader manufactured by Buss AG, Switzerland, and after cooling, it was pulverized using a hammer-type impact pulverizer.

The mixture was then filtered through a 150-mesh wire mesh to obtain various powder coatings.

After that, each powder coating was applied separately to a bonderite-treated steel plate with a thickness of 0.8 mm so that the film thickness after baking was 60 to 70 microns, and baked at 180°C for 20 minutes. Various cured coating films were obtained.

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. .

Blocking resistance... 15g of powder coating 40mmφ
20g/am" load and leave it at 35°C for 240 hours, then take out the sample. If it returns to its original powder state, it is considered to be "good" and blocking is observed. In some cases, it was marked as "defective".

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.

Overbake/recoatability...30 at 180"C
After baking for a minute, apply the same paint again and bake. Next, make 25 cross cants on the painted surface, peel off the cellophane tape in that area, and visually judge the degree of adhesion. did.

Stain resistance after exposure: It was visually determined whether dust and dirt accumulated on the coated surface after 6 months of outdoor exposure could be easily removed by simply washing with water.

O...Easily removed △...Partially remains ×...B that remains attached to the paint film and cannot be removed [Effects of the Invention] From the results shown in Table 3 As is clear, the thermosetting resin compositions of the present invention have better recoatability and practical exposure than those using resins that simply have fluorine atoms. It is known that it has a good balance of various physical properties without impairing the subsequent stain resistance, etc., and without impairing the weather resistance characteristic of such fluorine-containing resin powder coatings.

Claims (1)

[Claims] 1. Fluoroolefin copolymer having hydroxyl group (A)
, a vinyl copolymer (B) having at least one reactive polar group selected from the group consisting of a hydroxyl group, an acid group and a glycidyl group, and a curing agent (C). Curable resin composition. 2. The fluoroolefin copolymer (A) having a hydroxyl group described above has a number average molecular weight of 1,000 to 100,000 and a softening point determined by the ring and ball method of 60 to 150°C. , The thermosetting resin composition according to claim 1. 3. The vinyl copolymer (B) having at least one reactive polar group selected from the group consisting of a hydroxyl group, an acid group and a glycidyl group has a softening point according to the ring and ball method of 40 to 150°C. The thermosetting resin composition according to claim 1. 4. The vinyl copolymer (B) having at least one reactive polar group selected from the group consisting of a hydroxyl group, an acid group, and a glycidyl group described above is composed of cyclohexyl acrylate or cyclohexyl methacrylate and a carbon atom having 1 to 1 carbon atoms.
The total amount of alkyl acrylate or alkyl methacrylate having an alkyl group of 4 is 50% by weight or more, or 30% by weight of either the cyclohexyl (meth)acrylate or the alkyl (meth)acrylate. The thermosetting resin composition according to claim 1 or 3, which is obtained by using the thermosetting resin composition.