JPH0314076B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an instant-curing coating composition with excellent weather resistance. Conventionally, there has been a desire to develop a technology that allows the crosslinking reaction to proceed instantaneously after painting to complete the painting, and a coating machine with a built-in mixing zone is equipped with two components that quickly cause a crosslinking reaction (i.e., usually a base agent). Attempts have been made to introduce a method in which a compound (composed of a hardener and a curing agent) are introduced separately, mixed in a mixing zone, and then immediately discharged for coating. Despite the development of such technology, the development of materials that can be used in a wide range of applications as coating compositions has not yet been sufficiently developed. It is still not fully developed. Particularly in the fields of ship exteriors, building exteriors, road marking paints, and colored road pavements, the development of instant-curing coating compositions with such excellent weather resistance is strongly desired. ing. An object of the present invention is to provide an instant-curing coating composition that has excellent weather resistance and is particularly suitable for the above-mentioned uses. The above object of the present invention is achieved by providing a coating composition comprising the following main agent and curing agent. That is, the composition of the present invention has (a) the general formula

[Formula] (wherein, X represents an alkylene group, and R, R ¹ and R ² each represent an alkyl group or an alkenyl group) and a monomer of 3 to 40% by weight and the general formula

[Formula] (wherein R ³ represents a hydrogen atom or a methyl group, R ⁴ represents an alkyl group, a cycloalkyl group, an alkoxyalkyl group, or a tetrahydrofurfuryl group) contains not less than 20% by weight of the monomer as an essential monomer. A main agent consisting of a copolymer obtained by copolymerization of monomers as polymer components, and (b) general formula

[Formula] (wherein n represents 2 or 3) Polyvalent isocyanate and/or a cured oligomer obtained by the reaction of the polyvalent isocyanate and a polyhydric alcohol, and whose terminal group is an isocyanate group A coating composition comprising: The main ingredient (a) and the curing agent (b) are separately supplied to a mixing zone in a coating machine by a pump or the like and mixed to form the composition of the present invention, and at the same time,
It is discharged from the tip of the spray gun of the coating machine and coats the object to be coated. 2 contained in the base ingredient of (a)
The class amino groups and the isocyanate groups in the curing agent (b) react rapidly to form a tough, weather-resistant film within a very short time after coating. In particular, it has the feature that it is extremely easy to use from a practical point of view, as its properties are not affected in any way by rain immediately after painting. It is particularly suitable for fields such as color pavement. General formula used to obtain the copolymer that is the main ingredient of the composition of the present invention

In the monomer represented by the formula, X represents an alkylene group, and the alkylene group is preferably an ethylene group or a propylene group. In addition, R, R ¹ and R ² represent an alkyl group or an alkenyl group, and the most common compound is a case where R, R ¹ and R ² are all alkyl groups having 1 carbon atom, that is, methyl groups, but R , R ¹
Even if R ² is an alkyl group or an alkenyl group larger than a methyl group, the effects of the present invention will not be impaired. The most common preferred compounds are:
These are tertiary-butylaminoethyl methacrylate and tertiary-butylaminopropyl methacrylate. The content of this monomer in the copolymer is in the range of 3 to 40% by weight, and if it is less than 3% by weight, a sufficient crosslinking reaction with the curing agent will not occur, resulting in a drawback in the durability of the coating. Moreover, if the amount exceeds 40% by weight, the crosslinking reaction is too fast, often forming gels in the mixing zone of the coating machine or the tip of the spray gun, and causing so-called bumps on the coating film, which is unsuitable. In particular, the content of this monomer is preferably in the range of 10 to 30% by weight. General formula used to obtain the copolymer that is the main ingredient of the composition of the present invention

Specific examples of the monomer represented by the formula include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate,
Octyl acrylate, cyclohexyl acrylate, methoxyethyl acrylate, butoxyethyl acrylate, tetrahydrofurfuryl acrylate, methyl methacrylate, ethyl methacrylate,
Propyl methacrylate, butyl methacrylate, octyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, oleyl methacrylate, cyclohexyl methacrylate, tetrahydrofurfuryl methacrylate,
There are methoxyethyl methacrylate, butoxyethyl methacrylate, etc., which contain one or more types of acrylic ester and methacrylic ester monomers.
20% by weight or more is used. If the copolymerized amount of the acrylic ester and/or methacrylic ester is less than 20% by weight, the weather resistance will be insufficient and it will be unsuitable for the present invention. Preferably, a copolymerized material containing 30% by weight or more is used. The remaining monomers used to obtain the copolymer which is the main ingredient of the composition of the present invention include styrene, α
- Aromatic monomers such as methylstyrene, paramethylstyrene, vinyltoluene, dimethyl fumarate,
Diethyl fumarate, dibutyl fumarate, dioctyl fumarate, monobutyl fumarate, dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl itaconate, diethyl itaconate,
Mono- or diesters of unsaturated dibasic acids such as dibutyl itaconate and monobutyl itaconate, unsaturated nitriles such as acrylonitrile and methacrylonitrile, vinyl esters such as vinyl acetate and vinyl propionate, hydroxyethyl methacrylate, and methacrylate. Hydroxyl group-containing unsaturated monomers such as hydroxypropyl acid, hydroxyethyl acrylate, hydroxypropyl acrylate, allyl alcohol, unsaturated halogen compounds such as vinyl chloride and vinylidene chloride, acrylic acid, methacrylic acid, itaconic acid, crotonic acid , unsaturated carboxylic acids such as fumaric acid and maleic anhydride, nitrogen-containing unsaturated monomers such as acrylamide, methacrylamide, dimethylacrylamide, vinylpyrrolidone, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc., and the effects of the present invention. One or more types can be appropriately copolymerized and used within a range that does not inhibit. The copolymer which is the main component of the composition of the present invention generally has a number average molecular weight in the range of 1,000 to 20,000, but preferably 1,000 to 8,000 in order to reduce the amount of organic solvent used during coating. is preferably 1000 to 5000. The above copolymer can be produced by any known method such as solution polymerization, bulk polymerization, suspension polymerization, or emulsion polymerization, but in order to obtain the above preferred number average molecular weight, solution polymerization is used. It is most appropriate to manufacture the General formula of the curing agent component of the composition of the present invention

Specific examples of polyvalent isocyanates represented by the formula include α, α,
α′, α′-tetramethyl metaxylylene diisocyanate, α, α, α′, α′-tetramethyl paraxylylene diisocyanate, α, α, α′, α′α″,
α''-hexamethylmesitylene triisocyanate, etc., and the curing agent is one or more of these polyvalent isocyanates and/or the polyvalent isocyanate, for example, ethylene glycol, diethylene glycol, triethylene glycol,
Polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3 butanediol, 1,4 butanediol, polytetramethylene glycol, pentanediol, hexanediol, glycerin,
one or more polyhydric alcohols such as trimethylolethane, trimethylolpropane, pentaerythritol, trishydroxyethyl isocyanurate, and polycaprolactone in a ratio such that the isocyanate groups of the polyhydric isocyanate compound are in excess of the hydroxyl groups of the polyhydric alcohol. An oligomer having an isocyanate group at the molecular end obtained by the reaction is used. If the molecular weight of the above-mentioned oligomer is too large, compatibility with the copolymer which is the main ingredient may be inhibited, so it is preferable that the number average molecular weight is 2000 or less. The polyvalent isocyanate and oligomer that are the curing agent components of the composition of the present invention do not impair weather resistance, and the carbon atoms to which the isocyanate group is bonded are 2.
Because it has two methyl groups, the reactivity with the secondary amino group of the copolymer (a) is somewhat slow, and there is no phenomenon such as clumping due to reaction in a spray gun, and it is similar to the normal reaction system of amine and isocyanate. It is possible to solve the problems that have made it difficult to put it into practical use as a coating material. The above copolymer (a) and curing agent (b) are usually used dissolved in an organic solvent, such as various coloring materials such as titanium oxide, iron oxide, carbon black, phthalocyanine blue, calcium carbonate, barium sulfate, etc. , a filler such as silica, alumina, aluminum powder, glass flakes, glass beads, talc, etc. is dispersed and mixed in the copolymer solution of (a) or in both the curing agent of (a) and (b), The copolymer solution (a) and the curing agent (b) are each supplied from separate containers to the mixing zone of the coating machine using a metering pump, etc., and after being mixed in the mixing zone, they are immediately discharged from a spray gun, etc. It is coated on the object to be coated. At this time, the ratio of amino groups in the copolymer (a) to isocyanate groups in the curing agent (b) is in the range of 1:0.8 to 1.4, particularly preferably 1:1.0 to 1.2. , each component is preferably provided to a mixing zone. The mixing mechanism of the above-mentioned paint sprayers is, for example, forced stirring type, static mixer,
Alternatively, any of the known methods can be used, such as mixing mechanisms with high pump discharge pressures and impingement plate designs, but the average residence time in the mixing zone and at the tip of the spray gun is preferably less than 30 seconds, especially less than 10 seconds. It is desirable that the value be within the range of 100% to prevent gel from forming inside the paint sprayer. The coating thus formed on the object to be coated hardens within a few minutes, making it possible to apply the coating within a short period of time, and the coating has excellent weather resistance. Hereinafter, the present invention will be specifically explained with reference to Examples. Example 1 100 parts by weight of a 60% by weight toluene solution (number average molecular weight 3500) of a copolymer of 50% by weight butyl acrylate, 35% by weight methyl methacrylate and 15% by weight tert-butylaminoethyl methacrylate and 60 parts by weight of titanium oxide. part by weight, 40 parts by weight of toluene, and 40 parts by weight of ethyl acetate were dispersed in a sand mill, and the base agent (A-
1) was adjusted. On the other hand, 14.4 parts by weight of trimethylolpropane and
73.2 parts by weight of α, α, α', α'-tetramethyl metaxylylene diisocyanate was reacted to obtain a 50% by weight solution of polyvalent isocyanate oligomer in ethyl acetate, which was used as a curing agent (B-1). Using a Binks two-component paint sprayer, apply the main agent (A-
Adjust the discharge rate of the metering pump so that the discharge weight ratio of 1) and curing agent (B-1) is 8:1 (the equivalent ratio of NH in the main agent and NCO in the curing agent is 1:1.06). The coating was applied to a sandblasted steel plate to a dry film thickness of approximately 100μ. Although I applied the paint repeatedly, there were no spots on the paint film, and there was no clogging of the spray gun. The coating became tack-free after 3 minutes, and did not peel off even after wiping with lacquer thinner after 10 minutes. or,
As a result of evaluating the painted board in an accelerated weathering test using a Weather-O-meter, the gloss retention rate was 89 after 500 hours of irradiation.
It was %. Example 2 Styrene 10% by weight, n-butyl methacrylate 30%
100 parts by weight of a 60% by weight toluene solution (number average molecular weight 2700) of a copolymer of 35% by weight ethyl acrylate and 25% by weight tert-butylaminopropyl methacrylate, 60 parts by weight of titanium oxide and 40 parts by weight of toluene, A base ingredient (A-2) was prepared by dispersing 40 parts by weight of ethyl acetate using a sand mill. On the other hand, trifunctional polycaprolactone with a molecular weight of 800
80 parts by weight and 73.2 parts by weight of α,α,α′,α′-tetramethyl paraxylylene diisocyanate were reacted to obtain a 50% by weight solution of polyvalent isocyanate oligomer in ethyl acetate, which was used as a curing agent (B-2). . Using a Binks two-component paint sprayer, apply the main agent (A-
Adjust the discharge rate of the metering pump so that the discharge weight ratio of 2) and curing agent (B-2) is 3:1 (the equivalent ratio of NH in the main agent and NCO in the curing agent is 1:1.04), The coating was applied to a sandblasted steel plate to a dry film thickness of approximately 100μ. Although I applied the paint repeatedly, there were no spots on the paint film, and there was no clogging of the spray gun. The paint film became tack-free after 3 minutes and did not peel off even when wiped with lacquer thinner after 10 minutes. Example 1
An accelerated weathering test was conducted under the same conditions as above, and the gloss retention rate was 86%. Example 3 60% by weight of a copolymer of 20% by weight methyl methacrylate, 20% by weight dibutyl fumarate, 40% by weight ethyl acrylate, 5% by weight 2-hydroxyethyl acrylate and 15% by weight tert-butylaminoethyl methacrylate. % toluene solution (number average molecular weight 4800), 60 parts by weight of titanium oxide, 40 parts by weight of toluene, and 40 parts by weight of ethyl acetate were dispersed in a sand mill to prepare a main ingredient (A-3). On the other hand, 80 parts by weight of the curing agent (B-2) used in Example 2 and a 50% solution of α, α, α′, α′, α″, α″-hexamethylmesitylene triisocyanate (toluene,
Dissolved in a 1:1 mixed solvent of methyl ethyl ketone)20
A curing agent (B-3) was prepared by mixing parts by weight. Using the coating machine of Example 1, the discharge weight ratio of the main agent (A-3) and the curing agent (B-3) was 8:1 (the equivalent ratio of NH in the main agent and NCO in the curing agent was 1:1.05) By adjusting the discharge rate of the metering pump, the dry film thickness was approximately 100μ on the sandblasted steel plate.
It was painted to look like this. Although I applied the coating repeatedly, there were no spots on the coating, and there was no clogging of the spray gun. The coating became tack-free after 3 minutes, and did not peel off even after wiping with lacquer thinner after 10 minutes. Furthermore, as a result of evaluating the coated board in an accelerated weathering test using a Weather-O-meter, the gloss retention rate was 91% after 500 hours of irradiation. Comparative Example The main ingredient (A-1) used in Example 1 was used as the main ingredient. On the other hand, a polyvalent isocyanate oligomer (Desmodyur L, trade name manufactured by Bayer AG), which is an adduct of trimethylolpropane and tolylene diisocyanate, was made into a 50% ethyl acetate solution, and a curing agent (B
-4). Using the same coating machine as in Example 1, the main agent (A-
Adjust the discharge rate of the metering pump so that the discharge weight ratio of 1) and hardening agent (B-4) is 9:1 (the equivalent weight of NH in the main agent and NCO in the hardener is 1:1.06) and perform sandblasting. The dry film thickness is approx.
It was painted to have a thickness of 100μ. As the paint was applied repeatedly, spots gradually appeared on the paint film and the tip of the spray gun became clogged. The coating film is 3
After a few minutes, it became tack-free, and after 10 minutes, the coating did not come off even after wiping with lacquer thinner. When an accelerated weathering test was conducted under exactly the same conditions as in Example 1, the gloss retention rate was 32%, which was poor.

Claims (1)

[Scope of Claims] 1 (a) Monomers 3 to 40 represented by the general formula [Formula] (wherein X represents an alkylene group, and R, R ¹ and R ² each represent an alkyl group or an alkenyl group) Weight % and monomer represented by the general formula [Formula] (wherein R ³ represents a hydrogen atom or a methyl group, and R ⁴ represents an alkyl group, cycloalkyl group, alkoxyalkyl group or tetrahydrofurfuryl group) 20 weight % or more of a copolymer obtained by copolymerization of monomers as essential monomer components, and (b) a main ingredient represented by the general formula: A coating composition comprising a polyvalent isocyanate and/or a curing agent comprising an oligomer obtained by reacting the polyvalent isocyanate with a polyhydric alcohol and having an isocyanate group as a terminal group.