JP2814554B2 - Resin composition for coating - Google Patents

Description

The present invention relates to a novel and useful coating resin composition. More specifically, it comprises a specific vinyl copolymer having a siloxy group and an acid anhydride group and an epoxy compound as essential components, and is particularly excellent in storage stability,
The present invention relates to a coating resin composition which is excellent in low-temperature curability and, in addition, gives a coating film excellent in acid resistance and the like.

[Conventional technology]

In recent years, in the automotive industry,
From the viewpoints of the stability of the paint and the performance of the paint film, a paint system comprising an acrylic resin and a melamine resin is mainly used.

On the other hand, for off-line coating, a coating system comprising a combination of an acrylic resin and a polyisocyanate compound is often used from the viewpoint of low-temperature curability and appearance of a coating film.

However, even today, in the mainstream melamine-cured system, the appearance of the coating film cannot always be said to be excellent, and furthermore, due to the weak acid resistance of the melamine resin itself, due to acid rain during exposure. Deterioration of the coating film is observed.

In addition, in the case of a polyisocyanate curing system, the polyisocyanate compound itself has a problem of toxicity, and the pot life is short. Therefore, such a curing system is used for line coating which is used continuously and in large quantities. Is not suitable.

[Problems to be solved by the invention]

In order to solve each of these problems, of course,
Although a number of proposals have been made, it is a non-isocyanate-based and non-melamine-based film with excellent coating appearance, and can be used as a one-pack type, and can be used as a surplus or as an automobile outer panel. At present, a cured system having the above acid resistance has not been found yet.

However, the problem to be solved by the present invention is a novel form for non-isocyanate and non-melamine one-part curing from the viewpoint of both the future prospects in the automotive industry and the current analysis. It is an object of the present invention to provide a more practical coating material having the acid resistance of the grade required for automobile outer panels.

[Means for Solving the Problems] Therefore, the present inventors put a scalpel in the unsolved problems of the prior art as described above, and aimed at solving the problems to be solved by the invention as described above. As a result of intensive studies, a vinyl copolymer having a siloxy group and an acid anhydride group in one molecule and an epoxy compound obtained by polymerizing a specific vinyl monomer are contained as essential film-forming components. The present invention has been completed by finding new and useful coating resin compositions.

That is, the present invention provides a vinyl monomer (a) having at least one polymerizable unsaturated double bond (hereinafter abbreviated as an unsaturated bond) and a siloxy group, especially a trialkylsiloxy group, in one molecule. -1) and a vinyl monomer (a-2) having at least one unsaturated bond and an acid anhydride group in one molecule, or
The vinyl monomer (a-1), the vinyl monomer (a-2), and another vinyl monomer (a-) copolymerizable with both of the monomers (a-1) and (a-2).
3) a vinyl copolymer (A) obtained by polymerizing
And an epoxy compound (B) as an essential component, and if necessary, further comprising a catalyst for accelerating the dissociation of the siloxy group. Particularly, it has excellent storage stability, excellent low-temperature curability, and An object of the present invention is to provide a coating resin composition which gives a coating film having excellent acid resistance.

Here, first, a vinyl monomer having at least one unsaturated bond and a siloxy group in one molecule is represented by the general formula: Having a group represented by, for example,
In the presence of a so-called chlorine scavenger such as triethylamine or pyridine, various hydroxyl groups such as trialkylchlorosilane, triphenylchlorosilane, triarylchlorosilane, dialkylchlorosilane, dialkyldichlorosilane or dialkylhydrosilane described below. A compound obtained by reacting with a vinyl monomer contained therein, which is a compound obtained by trimethylsiloxyethyl (meth) acrylate, tritylsiloxypropyl (methyl) acrylate. , Trimethylsiloxybutyl (meth)
Acrylate, triethylsiloxyethyl (meth) acrylate, tributylsiloxypropyl (meth) acrylate, or triphenylsiloxyalkyl (meth)
Acrylate and the like, which may be used alone or in combination of two or more.

In addition, if only typical examples of the hydroxyl group-containing vinyl monomer are given as examples, a hydroxyl group such as β-hydroxyethyl (meth) acrylate, β-hydroxypropyl (meth) acrylate or β-hydroxybutyl (meth) acrylate may be used. Alkyl (meth) acrylates or N-methylolated (meth) acrylamide; β-hydroxyethyl (meth) acrylate with ε-caprolactone added thereto, for example, “Placcel FM, FA series” [Daicel Chemical Industries, Ltd. ) Products] and “TONE ^™ M-100” (a product of Union Carbide, USA); “Blemmer,” whose generic name is called polypropylene glycol monomethacrylate
"PP series" and "Blemmer PE series" whose generic name is called polyethylene glycol monomethacrylate)
[All are products of NOF Corporation]; or (meta)
Unsaturated carboxylic acids such as acrylic acid, maleic acid, fumaric acid or itaconic acid, and “Kajura E” (glycidyl esters of branched aliphatic monocarboxylic acids, manufactured by Shell, The Netherlands), glycidyl octylate or Monoglycidyl esters of monohydric carboxylic acids such as glycidyl ester of coconut oil, and adducts with monoepoxy compounds represented by monoglycidyl ethers such as butyl glycidyl ether.

The amount of the vinyl monomer (a-1) used is appropriately in the range of 1 to 5% by weight, preferably 5 to 30% by weight of the total amount of the monomers constituting the vinyl copolymer (A). is there. If less than 1% by weight,
It is not preferable because the effect of the monomer (a-1) cannot be expected.

Next, examples of the vinyl monomer (a-2) having an unsaturated bond and an acid anhydride group include maleic anhydride and itaconic anhydride, but are not limited to these. Not something.

The amount of the vinyl monomer (a-2) used is appropriately in the range of 1 to 50% by weight, preferably 5 to 30% by weight of the total amount of the monomers constituting the vinyl copolymer (A). is there. If less than 1% by weight,
It is not preferable because the effect of the monomer (a-2) cannot be expected.

Further, the use ratio of the vinyl monomer (a-1) and the monomer (a-2) as described above is such that the equivalent ratio of the siloxy group to the acid anhydride group is 1:05 to 1: 2.0. It is desirable to do.

Next, the other copolymerizable vinyl monomer (a-3) is, of course, any copolymerizable vinyl monomer (a-1) or (a-2) as described above. Can also be used, but if only typical examples are exemplified, C _{1 to} C ₂₂
(Meth) acrylates such as alkyl (meth) acrylate, glycidyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate or cyclohexyl (meth) acrylate, styrene, vinyltoluene, tert-butylstyrene or α-methylstyrene such aromatic vinyl monomers; (meth) acrylic acid, maleic acid, such as unsaturated carboxylic acids fumaric acid or itaconic acid or maleic acid, such as fumaric acid or itaconic acid unsaturated dicarboxylic acid and a C ₁ -C _18, Carboxyl group-containing vinyl monomers represented by monoesters with monohydric alcohols; diesters of such unsaturated dicarboxylic acids with monohydric alcohols of C _{1 to} C ₁₈ ; (meth) acrylamide, N- Methylol (meth) acrylamide if (Meth) acrylamides such as N-alkoxymethylated (meth) acrylamide; N, N-dialkylaminoalkyl (meth) acrylates such as N, N-diethylaminoethyl (meth) acrylate; Acrylates; or fluorine-containing vinyl monomers such as hexafluoropropylene or tetrafluoroethylene, and further, vinyl acetate, (meth) acrylonitrile, or α-olefins such as ethylene or propylene, or butadiene. Dienes and the like.

The amount of the vinyl monomer (a-3) to be used is appropriately in the range of 0 to 98% by weight, preferably 0 to 40% by weight. Depending on the performance, it is used alone or in combination of two or more.

To prepare the vinyl copolymer (A) from the various vinyl monomers listed above, a known and commonly used method may be used.
For example, it can be carried out by a solution polymerization method using a radical generator.

As such a radical generator, any of those generally used for polymerization of vinyl monomers can be used, and among them, azobis is a typical example. Isobutyronitrile,
Di-tert-butyl peroxide or benzoyl peroxide; and the solvent is, for example, an aromatic hydrocarbon such as toluene or xylene; an ester such as ethyl acetate, n-butyl acetate or cellosolve acetate; methyl ethyl ketone And ketones such as methyl isobutyl ketone and methyl amyl ketone. However, the use of a solvent, such as an alcohol-based solvent, that causes a reaction with an acid anhydride group during storage and increases the viscosity of the system should be avoided.

The number average molecular weight ( _n ) of the vinyl copolymer (A) thus obtained is suitably in the range of 1,000 to 50,000.

When _{n of the} copolymer (A) is less than 1,000,
In any case, the physical properties of the coating film cannot be sufficient, and in order to obtain the physical properties of the coating film, the copolymer (A)
It can also be said that the abundance of hydroxyl groups generated after the release of trialkylsiloxy groups, etc., the higher the hydroxyl value, the more easily the coating becomes brittle, whereas, if it exceeds 50,000, the coating film will inevitably The appearance, gloss and fleshy feel, and painting workability will be inferior.
Either case is not preferred.

Next, various compounds can be used as the above-mentioned epoxy compound (B). Among them, ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, Polyglycidyl ethers of polyhydric alcohols such as hexanediol diglycidyl ether, diglycidyl ether of bisphenol A or triglycidyl ether of glycerin; diglycidyl ester of phthalic acid, diglycidyl ester of isophthalic acid or diglycidyl ester of adipic acid Polyglycidyl esters of polyvalent carboxylic acids, such as glycidyl ether type epoxy resin of bisphenol A or bisphenol F, novolak type epoxy resin, or ester containing a hydantoin ring. Alkoxy, such as such as various epoxy resins of the resin, including so-called polyepoxy compounds, p-
Glycidyl ester ethers of oxybenzoic acid, or various vinyl polymers having an epoxy group in the side chain, and further, ethylene oxide, propylene oxide, butylene oxide, dodecene oxide, styrene oxide or cyclohexene oxide, or butyl glycidyl Ether or phenyl glycidyl ether, or glycidyl ether of p-pert-butylbenzoic acid, or a monoepoxy compound such as "Cardura E-10".

The use ratio of the vinyl copolymer (A) and the epoxy compound (B) is such that the equivalent ratio of the acid anhydride in the copolymer (A) to the epoxy group in the compound (B) is 0.5.
It is appropriate that the ratio be ２2.

When the coating resin composition of the present invention thus obtained is exposed to the atmosphere, it reacts with moisture in the air to form a siloxy group in the vinyl copolymer (A) constituting the resin composition. Is hydrolyzed to give the vinyl copolymer (A)
A hydroxyl group capable of reacting with an acid anhydride group therein is generated, but it is necessary to use a catalyst for promoting such hydrolysis, that is, a catalyst for promoting dissociation of a siloxy group.

Examples of the siloxy group dissociation accelerating catalyst (C) used as necessary include: phosphoric acid, phosphoric ester, or phosphite; p-toluenesulfonic acid or its amine salt; or benzoic acid, trichloroacetic acid, trifluoroacetic acid. Or various acidic catalysts such as naphthalenedisulfonic acid or an amine salt thereof, ethylenediamine, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, butylamine, dibutylamine, tert-
Amines such as butylamine, hexylamine or triethylamine; or various alkali catalysts such as lithium hydroxide, alkali metal hydroxides such as sodium hydroxide or potassium hydroxide, or alkyl titanates, octylates, dibutyltin dilaurate Or various carboxylic acid metal salts such as lead octylate, and further, various sulfide-type or methylcaptide-type organic tin compounds such as monobutyltin sulfide or dioctyltin mercaptite, or tetraethylammonium fluoride or fluorine such as cesium fluoride. Compounds that generate ions are effective and representative.

The dissociation accelerating catalyst (C) is added in an amount of 0.001 to 10% by weight, preferably 0.001 to 10 parts by weight, based on the vinyl copolymer (A).
A range of 0.005 to 8% by weight is appropriate.

Contrary to the above, the coating resin composition of the present invention is a partner of a reaction with an acid anhydride group, which occurs in a molecule or between molecules of the vinyl copolymer (A) unless exposed to the atmosphere. Although a hydroxyl group is not generated, it can be a one-pack type, highly stable paint, but in order to ensure long-term storage stability, always capture a small amount of moisture that enters for some reason. It is desirable to prepare such a shape in advance.

That is, to add a so-called water binder (water scavenger) having reactivity with moisture is a wise measure for securing such long-term stability, and by doing so, it is possible to increase the long-term stability. Extended storage stability will be ensured.

Needless to say, the water binder may be added at the time of preparing the vinyl copolymer (A). When preparing the copolymer (A), the water binder is mixed in advance in the initial stage. You can also keep.

Particularly representative examples of the water binder include trialkyl orthoformates such as trimethyl orthoformate, triethyl orthoformate and tributyl orthoformate; orthoalkyl salts such as trimethyl orthoacetate, triethyl orthoacetate and tributyl orthoacetate. Trialkyl acetates Trialkyl orthoborate such as trimethyl orthoborate, triethyl orthoborate, tributyl orthoborate; tetramethylsilicate, tetraethylsilicate, tetrabutylsilicate, tetra (2-methoxyethyl) silicate or tetra (2-chloroethyl) silicate Tetra (substituted) alkyl silicates alone such as; tetraphenyl silicate or tetrabenzyl silicate;
The same active substances as the above-mentioned tetra (substituted) alkyl silicates (hereinafter abbreviated as the same simple substance); or dimer, trimer, tetramer or hexamer of tetraethyl silicate, “ethyl silicate 40” [manufactured by Colcoat Co., Ltd., A mixture of tetra (substituted) alkyl silicates, a condensate of the same effective silicates, or a phenylisocyanate, such as a tetramer, pentamer or hexamer mixture of tetraethylsilicate. , P-chlorophenyl isocyanate, benzenesulfonyl isocyanate, p-toluenesulfonyl isocyanate or isocyanate ethyl methacrylate (isocyanate group-containing monomer manufactured by Dow Chemical Company, USA)
And isocyanate group-containing compounds.

The amount of the water binder used is appropriately in the range of 0.1 to 30% by weight, preferably 0.5 to 20% by weight based on the vinyl copolymer (A).

The composition of the present invention thus obtained can be used as a clear coating as it is, or can be used as an enamel coating by further mixing a pigment.

In addition, the composition of the present invention may be blended with various conventional additives such as a leveling agent, an ultraviolet absorber or a pigment dispersant, if necessary. An agent or a polyester resin can also be compounded.

Further, as the coating method, a known and commonly used method such as brush coating, spray coating or roll coating can be adopted, and as the curing method, the composition of the present invention can be used in a wide range from room temperature drying to forced drying (heat drying). The optimal curing conditions are designed according to the combination of the copolymer component and the cross-linking agent component.

The thus obtained coating resin composition of the present invention is in the form of a solution or in the form of a powder, for automobiles, for automobile repair,
It can be used in a wide variety of applications, such as for home appliances or exterior materials for building materials, as well as for pre-coating of metals, etc., especially in the field where storage stability is required in the form of one-pack paints. The effect is remarkable.

〔The invention's effect〕

As described above, the coating resin composition of the present invention has a number average molecular weight of 1,000 to 50,000 and a vinyl copolymer having at least one siloxy group and an acid anhydride functional group (reactive polar group). It is composed of a polymer, an epoxy compound, and, if necessary, a dissociation accelerating catalyst, and reacts with moisture (humidity) in the air to form a siloxy group in the vinyl copolymer. Hydroxyl groups are formed and then cross-linked by reacting with the acid anhydride groups-such steps are predominantly intramolecular or intermolecular cross-linking of the vinyl copolymer-carboxyl groups occur, Subsequently, a strong coating film is formed through a so-called composite curing method in which further cross-linking occurs between the carboxyl group and the epoxy group in the epoxy compound. Excellent sex, among other things, is extremely useful as a one-coating.

〔Example〕

Next, the present invention by reference examples, examples and comparative examples,
More specifically, in the following, parts and%
All are by weight unless otherwise specified.

Reference Example 1 [Preparation Example of Vinyl Copolymer (A)] 138 parts of trimethylsiloxyethyl methacrylate,
190 parts of styrene, 356 parts of n-butyl acrylate, 249 parts of methyl methacrylate and 67 parts of maleic anhydride
Part of the monomer mixture consisting of 200 parts, 700 parts of toluene and 5 parts of azobisisobutyronitrile (AIBN).
And 10 parts of tert-butyl perbenzoate in a four-necked flask equipped with a stirrer, thermometer, condenser and inert gas inlet, heated to 90 ° C., and kept at the same temperature for 1 hour Then, it took 30 minutes to raise the temperature to 110 ° C., and 800 parts of the remaining monomer mixture, 25 parts of AIBN, and 300 parts of toluene were added dropwise over 4 hours, respectively. After completion of the reaction, the polymerization reaction was continued by maintaining the same temperature for 5 hours, and the target copolymer (A) having a nonvolatile content of 51.0% and a Gardner viscosity at 25 ° C (hereinafter the same) of OP was OP. A solution was obtained. Hereinafter, this is referred to as a copolymer (A-1)
The trimethylsiloxy group: acid anhydride group equivalent ratio is 1: 1 and the number average molecular weight is 10,000.
It was 0.

Reference Example 2 (same as above) 360 parts of trimethylsiloxyethyl methacrylate,
A monomer mixture consisting of 20 parts of styrene, 172 parts of itaconic anhydride and 268 parts of lauryl methacrylate,
In a place where 700 parts of xylene was previously charged in the same reaction vessel as in Reference Example 1 and heated to 120 ° C., 300 parts of xylene and 30 parts of tert-butyl peroctoate (TBPO) were added. It was added dropwise over 6 hours. After the completion of the dropwise addition, the polymerization reaction was continued at the same temperature for 6 hours, and the non-
A light yellow target copolymer (A) solution having a viscosity of 0.2% and having a UV value was obtained. Hereinafter, this is referred to as a copolymer (A-2)
Which has an equivalent ratio of trimethylsiloxy groups: anhydride groups of 1: 1 and a number average molecular weight of 15,000.
It was 0.

Reference Example 3 (same as above) 194 parts of triphenylsiloxyethyl acrylate,
A monomer mixture consisting of 100 parts of styrene, 54 parts of maleic anhydride, 300 parts of 2-ethylhexyl acrylate and 352 parts of n-butyl methacrylate was previously placed in a reaction vessel similar to that of Reference Example 1 in 150 parts of methyl amyl ketone. And 35 parts of TBPO, 60 parts of xylene, and 60 parts of methyl amyl ketone were added dropwise to a place where 150 parts of and xylene were charged and heated to 120 ° C. over 6 hours, After the completion of the dropwise addition, the polymerization reaction was continued while maintaining the same temperature for 6 hours to obtain a transparent target copolymer (A) solution having a non-volatile content of 71.3% and a viscosity of A ₂ -A ₁ . . Hereinafter, this is abbreviated as copolymer (A-3), which has a triphenylsiloxy group: acid anhydride group equivalent ratio of 1: 1.1, and
The number average molecular weight was 7,000.

Reference Example 4 (same as above) 100 parts of trimethylsiloxybutyl vinyl ether,
100 parts of vinyl benzoate, 350 parts of vinyl acetate,
10 "(Shell, Netherlands), a monomer mixture consisting of 400 parts of a vinyl ester of a branched aliphatic monocarboxylic acid and 500 parts of maleic anhydride, and 200 parts of toluene.
A mixture consisting of 50 parts of TBPO was added dropwise in 5 hours to a place where 800 parts of toluene was previously charged in a reaction vessel similar to that of Reference Example 1 and heated to 90 ° C. After completion of the polymerization, the polymerization reaction was continued at the same temperature for 7 hours to obtain a target copolymer (A) solution having a nonvolatile content of 50.3% and a viscosity of DE. Hereinafter, this is abbreviated as copolymer (A-4), which had an equivalent ratio of trimethylsiloxy groups: acid anhydride groups of 1: 1 and a number average molecular weight of 13,000.

Examples 1 to 5 and Comparative Examples 1 to 3 Various paints were prepared in accordance with the composition ratios as shown in Table 1.

"Acridic A-800" used in Comparative Examples 2 and 3 is an acrylic polyol manufactured by Dainippon Ink and Chemicals, Inc., and has a nonvolatile content of 50%.
%, And the hydroxyl value of the solid content is 100. Both the siloxy group and the acid anhydride group are absent.

Then, apply each paint separately to Bonderite #
Spray coating on 144 treated steel sheet (thickness 0.8 mm), and in the case of Examples 1 to 4 and Comparative Example 1, baking was first performed at 80 ° C. for 30 minutes, and then at 100 ° C. for 30 minutes. On the other hand, in the case of the melamine curing system as in Comparative Example 2, baking in a relatively high temperature range of 140 ° C. for 30 minutes was performed, and in the case of the isocyanate curing system as in Comparative Example 3, At 80 ° C. for 30 minutes in a relatively low temperature range to obtain cured coating films.

Thereafter, the storage stability of each paint and the performance of each cured coating film were compared and examined. The results are as summarized in the table.

The storage stability of these paints and the evaluation of the coating film performances were determined in the following manner.

Gloss ...... 60 degrees using a mirror reflectivity hardness ...... pencil hardness Erichsen value ...... Erichsen tester was measured, the processing of displaying adhesion ...... 1 cm ² in mm, draw the squares of ² becomes size 1 mm, A cellophane tape was adhered to the cut portion, and then the cellophane tape was peeled off and indicated by the number of remaining gobangs. Water resistance: The state of the coating film after immersion in warm water at 40 ° C for 10 days was visually determined. Acid resistance: A 5% H ₂ SO ₄ aqueous solution is dropped on the coating film, dried at 70 ° C. for 1 hour, and then washed with water to visually determine the state of the coating film. Alkali resistance: 5% NaOH aqueous solution Visually determine the change in the state of the coating film after immersion in it for 24 hours. Weather resistance: Measure the gloss retention after 2,000 hours of irradiation with a QUV tester and display as a percentage. Solvent resistance: … Contact the painted surface with gauze soaked in xylene
Visually determine the state of the coating film after rubbing 10 times with a load of 1.5 kg. Storage stability ... The paint was kept in Iwata cup for 12 seconds.
Viscosity in Iwata cup at 25 ° C after diluting with xylene and storing at 50 ° C for 8 days (seconds) Footnotes in Table 1: "Super Beckamine L-117-60": butyl etherified melamine, manufactured by Dainippon Ink and Chemicals, Inc .; non-volatile content = 60% "Barnock DN-950": poly, manufactured by Dojo Isocyanate compound; non-volatile content = 75%, isocyanate group content = 12 to 13% "Denacol Ex612": Polyglycidyl ether of sorbitol manufactured by Nagase & Co., Ltd. "Beckamine p-198": Dainippon Ink and Chemicals, Inc. Co., Ltd., phosphate ester-based curing accelerator; acid value = 350-4
50 As is clear from Table 1, the coating resin composition of the present invention containing a vinyl copolymer having both a siloxy group and an acid anhydride group in one molecule and an epoxy compound as essential components, It is known that it is excellent in storage stability and gives a coating film having excellent acid resistance and low-temperature curability.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09D 163/00-163/10 C09D 143/04 C09D 135/00

Claims (2)

(57) [Claims] 1. A vinyl monomer having at least one polymerizable unsaturated double bond and a siloxy group in one molecule (a-
1) a vinyl copolymer (A) obtained by polymerizing a vinyl monomer (a-2) having at least one polymerizable unsaturated double bond and an acid anhydride group in one molecule; A coating resin composition comprising the compound (B) and, if necessary, the above-mentioned siloxy group dissociation accelerating catalyst (C). 2. A vinyl monomer having at least one polymerizable unsaturated double bond and a siloxy group in one molecule (a-
1) and a vinyl monomer (a-2) having at least one polymerizable unsaturated double bond and an acid anhydride group in one molecule
And both vinyl monomers (a-1) and (a-
2) and a vinyl copolymer (A) obtained by polymerizing another copolymerizable vinyl monomer (a-3), an epoxy compound (B), and, if necessary, dissociation of the siloxy group. A coating resin composition comprising a promoting catalyst (C).