JPH0134469B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel curable coating composition, and more particularly to a composition using a urethane resin composition as a color vehicle. [Industrial Application Fields] Traditionally, two-component paints consisting of polyisocyanate compounds and polyol (hydroxyl group-containing) resins have been used for painting and repairing industrial machinery, buildings, structures, automobile repair, furniture (including steel), etc. Resin compositions are widely used as room temperature drying paint compositions. [Prior Art] However, in recent years, with the demand for reducing the number of coats and shortening the time required for painting operations such as topcoating, there has been a strong demand for urethane resin paint compositions that can be coated thickly in one coat and dry quickly. . However, conventional coating compositions require 4 to 5 coatings to form a thick film. As one method for improving this drawback, an attempt has been made to add and mix petroleum resin or the like to a low molecular weight polyol resin, which is one of the components of the urethane resin coating composition. However, although the composition obtained by the above-mentioned improved method was improved in terms of thick film properties, the coating properties such as solvent resistance were deteriorated, and the drying properties (curing properties) were also poor. Therefore, after applying the urethane resin paint composition, the adhesion of dirt and dust to the painted surface can be reduced, and even if the top coat is applied over a short period of time, the color of the undercoat film will not bleed, and the undercoat film will not bleed. There is a desire for a quick-drying urethane resin coating composition that can speed up painting operations, such as its abrasive properties and the ability to apply masking tape in a short time. [Problems to be Solved by the Invention] Therefore, the following quick-drying urethane resin coating compositions have been proposed. That is, a 4,4'-methylenebis(phenyl isocyanate)-based compound is used as the polyisocyanate compound that is the curing agent component, and a polyol resin with a low molecular weight, high nonvolatile content, and a high number of hydroxyl groups is used as the polyol resin that is the main component. This is a composition in which a reaction accelerator (organotin compound, amine, etc.) is added. However, this type of composition has the problem that when it is applied to a thick film, the film contains air bubbles, which deteriorates the appearance of the film and also reduces the performance of the film, such as rust prevention. It was hot. As mentioned above, the coating film obtained from the urethane resin composition, which can be applied in one coat to form a thick film without bubbles and dries quickly, has low permeability to corrosive substances such as moisture, so it has poor rust prevention properties. The various properties of the coating film are greatly improved, and at the same time, it has many advantages such as improving the appearance of the coating film and also improving the workability. Nevertheless, as mentioned above, the reality is that a composition with sufficient performance to be put to practical use has not been obtained to date. In view of the above-mentioned current situation, the present inventors have conducted extensive research and have discovered a urethane resin curable coating composition that can be applied to a thick film in one coat, has quick drying properties, and does not generate bubbles. The invention has been completed. [Means and effects for solving the problems] That is, the present invention provides (a) a ratio NCO/OH of the number of isocyanate groups of a polyisocyanate compound to the number of hydroxyl groups of a polyol resin having a hydroxyl value of 50 to 500, of 0.3 to 1.5; 100 parts by weight of the urethane resin composition (solid content), (b) 0.01 to 10 parts by weight of peroxide, and (in another embodiment, if necessary) (c) 1 to 30 parts by weight of water adsorbent. A curable coating composition comprising: As the polyol resin used in the composition of the present invention, any polyol resin that has a hydroxyl value of 50 to 500 and is commonly used for paints can be used. For example, ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 2,2,4-trimethine-1,3-pentanediol, hexamethylene glycol, cyclohexanedimethanol, trimethylolpropane, hexanetriol, glycerin, pentaerythritol, Sorbitol, sucrose, castor oil,
A compound containing active hydrogen such as ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, hexamethylenediamine, water, hydroxyl group-containing vinyl monomer, polyether polyol, polyester polyol, polyamide, hydroxyl group-containing acrylic resin, etc. Epoxy-modified polyol resin obtained by polyaddition reaction with an epoxy resin containing 2-hydroxyethyl (meth)acrylate,
A hydroxyl group-containing monomer such as 2-hydroxypropyl (meth)acrylate, (meth)acrylic acid alkyl ester, (meth)acrylic acid, styrene,
Acrylic polyol resins obtained by copolymerization with α,β-monoethylenically unsaturated monomers such as vinyltoluene; alkyd resins obtained by condensation reactions from oils or fatty acids, polyhydric alcohols, and polybasic acids; Acrylic modified alkyd resins grafted with various monomers used in the production of acrylic resins; Polyester resins obtained by condensation reaction of polyhydric alcohols and polybasic acids; Cellulose derivative resins, polyether resins, etc. ,
Examples include one kind or a mixture of two or more kinds of natural resins. The weight average molecular weight of the polyol resin is approximately 300
~100000 is preferred. More preferably about
800-30000. In the polyol resin used in the present invention,
If the hydroxyl value is less than 50, the crosslinking density with the isocyanate compound will be low and sufficient coating properties will not be obtained. On the other hand, if the hydroxyl value exceeds 500,
The water resistance and moisture resistance of the paint film will decrease. Therefore, it is preferable that the hydroxyl value is 50 to 500. The curable coating composition of the present invention particularly preferably contains the above-mentioned epoxy-modified polyol resin having a molecular weight of about 800 to 30,000, or the resin as a main component, and includes acrylic resins, epoxy resins, acrylated alkyd resins,
Cellulose derivative resin, alkyd resin, petroleum resin,
This is an epoxy-modified polyol resin composition containing less than 50% by weight of a mixture containing one or more resins containing or not containing hydroxyl groups, such as natural resins, polyester resins, and polyether resins. Further, the polyisocyanate compound used in the coating composition of the present invention acts as a crosslinking agent for the polyol resin and is a known compound in itself, and has two free or blocked isocyanate groups in one molecule. This is a compound having the above. That is, diisocyanate compounds, triisocyanate compounds, isocyanate adducts having two or more terminal isocyanate groups in one molecule obtained by reacting a di- or triisocyanate compound with an active hydrogen-containing compound, and di- or triisocyanates thereof. Examples include blocked isocyanate compounds obtained by blocking free isocyanate groups of a compound or an isocyanate adduct with a blocking agent. Among these, the polyisocyanate compounds belonging to ~ above easily react with the polyol resin,
Since it cures, the curable coating of the present invention is suitable for use as a cold-curing type. When polyisocyanate compounds belonging to the above group are heated, the blocking agent dissociates, reacts with the polyol resin, and cures, so that the composition of the present invention is suitable for use in a heat-curable form. Examples of the isocyanate compounds listed above and in the above categories include aliphatic isocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, isophorone diisocyanate, isophorone diamine diisocyanate, toridine diisocyanate, and dimer acid diisocyanate; Diisocyanate, methylxylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, naphthylene diisocyanate, 4,4'-methylene bis(phenyl isocyanate), 4,4'-ethylene bis(phenyl isocyanate), 3,3'- Diisocyanate, 1,4-dimethylenebenzene, 3,3'-diisocyanate diethylbenzene, 3,3'-diisocyanate dimethyltoluene 3,3'-diethyltoluene, 3,3'-isocyanate diethylxylene, triphenylmethane diisocyanate, diphenylene Aromatic isocyanates such as nealmethane diisocyanate, metaphenylene diisocyanate, and diphenylmethane triisocyanate, and alicyclics such as 1-methyl-2,4-diisocyanate cyclohexanone, 4,4'-methylenebis(cyclohexyl isocyanate), and cyclohexane diisocyanate. Examples include group-based isocyanates. Further, the polyisocyanate compound belonging to the above group has two or more, preferably two to three terminal free isocyanate groups in one molecule obtained by reacting the di- or triisocyanate compound with an active hydrogen-containing compound. It is an isocyanate adduct. Examples of the active hydrogen-containing compound include ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, 2,
2,4-trimethyl-1,3-pentadiol,
Hexamethylene glycol, cyclohexanedimethanol, trimethylolpropane, hexanetriol, glycerin, pentaerythritol,
Examples include sorbitol, sucrose, castor oil, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, hexamethylenediamine, water, polyether polyol, polyester polyol, polyamide, and hydroxyl group-containing acrylic resin. The addition reaction between these di- or triisocyanate compounds and the active hydrogen-containing compound can be carried out by a known method. Further, the polyisocyanate compound belonging to the above category is a compound in which the isocyanate group of the polyisocyanate compound belonging to the above category .about. is blocked with a blocking agent. Examples of isocyanate group blocking agents include phenol, thiourea, methanol, propanol, n-butanol, t-butanol, ethylene chlorohydrin, 1,1-dichloro-2-propanol, ethyl acetoacetate, dimethyl malonate, 2 - Examples include mercaptobenzothiozole, other oximes, and caprolactams.
Blocking of isocyanate groups with such a blocking agent can be carried out by a known method. In the coating composition of the present invention, the ratio NCO/OH of the number of isocyanate groups in the polyisocyanate compound to the number of hydroxyl groups in the polyol resin is 0.3 to
Must be in the range of 1.5. In the above range, if NCO/OH is less than 0.3, or
If NCO/OH exceeds 1.5, the balance of crosslinking is lost, making it difficult to obtain the desired coating performance of the present invention, which is not preferred. The most preferred NCO/OH range is 0.5-1.2. Further, any organic peroxide containing active oxygen can be used in the curable coating composition of the present invention. For example, benzoyl peroxide, parachlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, caprylyl peroxide, lauroyl peroxide, acetyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, bis(1
-Hydroxycyclohexyl peroxide),
Hydroxyheptyl peroxide, tert-butyl hydroperoxide, p-menthane hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexyl-2,5-dihydroperoxide, di-tert-butyl peroxide, dicumyl peroxide Oxide, 2,5-dimethyl-2,5-di(tert-butylperoxine) hexane, 2,5-dimethylhexyl-2,5-di(peroxine benzoate) tert-butyl perbenzoate, tert-butyl peracetate ,
tert-butyl peroctoate, tert-butyl peroxyisobutyrate, di-tert-butyl di-
Examples include perphthalate and succinic peroxide. These peroxides can be used alone or in combination of two or more. In the composition of the present invention, the peroxide is used in an amount of 0.01 to 10 parts by weight based on a total of 100 parts by weight (solid content) of the polyol resin and polyisocyanate compound. If the amount of peroxide is less than 0.01 part by weight within the above range, the effect of suppressing bubble generation, which should be solved by the present invention, cannot be obtained. On the other hand, if more than 10 parts by weight is used, the various properties of the polyurethane coating will deteriorate. Therefore, it is preferable to use the peroxide in an amount of 0.01 to 10 parts by weight. Furthermore, as another aspect, the present invention includes a composition in which a moisture adsorbent is further used in combination with a polyol resin, a polyisocyanate compound, and a peroxide. As the moisture adsorbent, known ones such as natural zeolite, synthetic zeolite, orthoformic acid methyl ester, orthoformic acid ethyl ester, orthoacetic acid methyl ester, etc. can be used singly or as a mixture of two or more. The water adsorbent is used in an amount of 1 to 30 parts by weight based on 100 parts by weight (solid content) of the polyol resin and polyisocyanate compound. If the amount of water adsorbent used exceeds 30 parts by weight, the appearance of the coating film will be impaired and various properties such as water resistance will also deteriorate, which is not preferable. The composition of the present invention uses an organic solvent that dissolves the polyol resin and polyisocyanate compound as a medium. Examples of the organic solvent include ethyl acetate,
Ester solvents such as butyl acetate and isobutyl acetate, ether ester solvents such as ethylene glycol monoethyl ether acetate, xylene,
Aromatic solvents such as toluene, ketone solvents such as methyl isobutyl ketone, methyl ethyl ketone, etc. may be used in appropriate combinations. polyol resin, polyisocyanate compound,
The solid content concentration in the composition consisting of peroxide and an optional water adsorbent is preferably about 10 to 98% by weight. In particular, when the pigment described below is used in combination, the solid content concentration in the composition is preferably 20 to 95% by weight.
A range of 25 to 90% by weight is suitable. If the solid content concentration is less than 10% by weight, it will not be possible to obtain a sufficient film thickness, and if it exceeds 98% by weight, leveling agents,
Additives such as anti-cissing agents and anti-settling agents cannot be mixed in, reducing painting workability. The coating composition of the present invention may contain various additive components normally used for paints, such as color pigments, extender pigments, dyes, catalysts (organotin compounds, amines, etc.), bituminous substances, and various additives, as necessary. It can be used by adding and mixing. When the curable coating composition of the present invention is used as a room temperature curable coating composition, it can be prepared as follows. First, add 1 to 100 parts by weight of a resin solution with a solid content of 25 to 98% by weight, in which the polyol resin is dissolved in an organic solvent, and an appropriate organic or inorganic pigment if necessary.
Add 900 parts by weight, and leveling agent if necessary.
Additives such as anti-cissing agents, anti-settling agents, and moisture adsorbents are added and uniformly kneaded and dispersed to form the paint base. On the other hand, a polyisocyanate compound is dissolved in an organic solvent at a concentration of 20% by weight or more and used as a curing agent for paint. Immediately before use as a paint, the main agent and curing agent are mixed in such a way that the ratio of the number of isocyanate groups in the polyisocyanate compound to the number of hydroxyl groups in the polyol resin, number of NCO groups/number of OH groups, is in the range of 0.3 to 1.5, preferably 0.5 to 1.2. Mix in proportions. Further, a peroxide is mixed with 100 parts by weight of the urethane resin composition at a ratio of 0.01 to 10 parts by weight, preferably 0.05 to 8 parts by weight, and coated with an organic solvent if necessary. Dilute so that the amount of forming components is 10-95% by weight. Incidentally, the peroxide can also be mixed in advance into the paint base material. Further, when the coating composition of the present invention is used as a thermosetting coating composition, a blocked isocyanate compound and a peroxide can be mixed in advance with the paint base. (It can be used as a so-called one-component type.) The composition of the present invention can be applied using ordinary coating equipment such as a brush, roller, or spray, and after application, it must be dried at room temperature or heated at 60 to 250°C for 10 to 40 minutes. to obtain a coating film. As mentioned above, the coating composition of the present invention can be coated thickly (film thickness: 50 to 500 μm) in one coat, and does not generate bubbles even when cured and dried quickly. Furthermore, by making it harden quickly, there is less adhesion of dirt, dust, etc., polishing and masking can be done in a short time after painting, and there is no smearing even after repeated coatings. That is, by using the coating composition of the present invention, a coating film with excellent coating workability and performance can be obtained. The details of the present invention will be explained above using examples. "Part" or "%" indicates "part by weight" or "% by weight", respectively. Paint base A: Epoxy-modified polyol resin [manufactured by Asahi Denka Co., Ltd., trade name: Adeka Resin EPX-6080: hydroxyl value 105:60
% toluene/methyl isobutyl ketone mixed solution]
40 parts, titanium oxide 25 parts, talc 25 parts and xylene
10 parts were kneaded in a roll mill to obtain a white paint base A. Paint main component B Epoxy-modified polyol resin [manufactured by Dainippon Ink and Chemicals Co., Ltd., trade name Epicron H201BT: hydroxyl value 200: 60% toluene/methyl isobutyl ketone mixed solution] 40 parts, titanium oxide 25 parts, talc 25 parts,
and 10 parts of xylene were kneaded in a roll mill to obtain a white paint base B. Paint main component C Epoxy-modified polyol resin [manufactured by Dainippon Ink and Chemicals Co., Ltd., trade name Epiclon NS260-80X: hydroxyl value 360: 80% xylene solution] 30 parts, titanium oxide 25 parts, talc 25 parts, and xylene 20 parts. The mixture was kneaded in a roll mill to obtain a white paint base C. Paint main component D Epoxy modified polyol resin [manufactured by Dainippon Ink & Chemicals Co., Ltd., product name U251-60BT: hydroxyl value
225: 60% toluene/methyl isobutyl ketone mixed solution] 28 parts, epoxy resin [manufactured by Ciel Chemical Co., Ltd.,
Trade name Epicote #1001: hydroxyl value 9.5: 12 parts of 60% xylene solution], 25 parts of titanium oxide, 25 parts of talc, and 10 parts of xylene were kneaded in a roll mill to obtain paint base D. Paint base material E: 28 parts of epoxy-modified polyol resin (same as paint base D), saturated polyester polyol resin [manufactured by Dainippon Ink & Chemicals Co., Ltd., trade name: Burnock]
DE140-70: Hydroxyl value 136: 70% xylene/methyl isobutyl ketone mixed solution] 10 parts, titanium oxide
25 parts of talc, 25 parts of talc, and 12 parts of xylene were kneaded in a roll mill to obtain a white paint base E. Paint base material F Acrylic polyol resin [manufactured by Dainippon Ink & Chemicals Co., Ltd., trade name Acrydik A850: Hydroxyl value
100], 25 parts of titanium oxide, 25 parts of talc, and 10 parts of xylene were kneaded in a roll mill to obtain a white paint base F. Paint base agent G Castor oil (hydroxyl value 161) 40 parts, titanium oxide 25
25 parts of talc and 10 parts of xylene were kneaded in a roll mill to obtain a white paint base G. Paint base material H Polyether polyol resin [Takeda Pharmaceutical Co., Ltd.
Manufactured by Takerakku 922: Hydroxyl value 110〕40 parts,
25 parts of titanium oxide, 25 parts of talc, and 10 parts of xylene were kneaded in a roll mill to obtain a white paint base H. Examples and Comparative Examples Peroxide and polyisocyanate compound [tolylene diisocyanate adduct: manufactured by Bayer AG, trade name Dismodule L,
or methylene diisocyanate: manufactured by Dainippon Ink & Chemicals Co., Ltd., trade name Epicron B-907], catalyst,
The moisture adsorbent and the solvent were blended in the proportions shown in Tables 1 and 2 to obtain coating compositions of Examples and Comparative Examples. Various performance comparison tests were conducted on the obtained coating composition, and the results are shown in Table 3.

【table】

【table】

【table】

【table】

【table】

[Effects of the present invention]

The effects of the present invention will be explained below based on the comparative test results shown in Table 3 above. In the coating film obtained from the curable coating composition that does not contain peroxide shown as a comparative example, the generation of bubbles, which has been a problem in the past, was observed, and rusting and adhesion were observed in the salt spray resistance test. In the test, peeling was observed on some of the paint films. On the other hand, the coating film obtained from the curable coating composition of the present invention did not have the generation of air bubbles in the coating film, which had been a problem in the past, although it dried as quickly as the comparative example. The appearance of the coating film was good, particularly in Examples 17 to 21. Further, in tests regarding water resistance, adhesion, and salt spray resistance, no abnormalities were observed in the coating film. That is, the curable coating composition of the present invention can be applied to a thick film in one go, has quick drying properties, and can form a coating film without generating bubbles, and the resulting coating film has water resistance, Adhesion and salt water spray resistance were also very excellent.

Claims (1)

[Claims] 1 (a) 100 parts by weight of a urethane resin composition in which the ratio NCO/OH of the number of isocyanate groups of a polyisocyanate compound to the number of hydroxyl groups of a polyol resin with a hydroxyl value of 50 to 500 is in the range of 0.3 to 1.5 ( solid content) and (b)
0.01 to 10 parts by weight of peroxide. 2. The curable coating composition according to claim 1, wherein the polyol resin having a hydroxyl value of 50 to 500 is an epoxy-modified polyol resin. 3 (a) 100 parts by weight (solid content) of a urethane resin composition in which the ratio NCO/OH of the number of isocyanate groups of a polyisocyanate compound to the number of hydroxyl groups of a polyol resin with a hydroxyl value of 50 to 500 is in the range of 0.3 to 1.5. ) A curable coating composition comprising 0.01 to 10 parts by weight of a peroxide, and (c) 1 to 30 parts by weight of a moisture adsorbent. 4. The curable coating composition according to claim 3, wherein the polyol resin having a hydroxyl value of 50 to 500 is an epoxy-modified polyol resin. 5. The curable coating composition according to claim 3, wherein the moisture adsorbent is a zeolite.