JPH06905B2 - Coating composition with excellent storability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to coating compositions with significantly improved storability.

As a coating material excellent in weather resistance and flexibility that can be used at room temperature, conventionally, a hydroxyl group-containing acrylic resin or polyester resin is crosslinked with an aliphatic or alicyclic or alicyclic polyvalent isocyanate. The so-called non-yellowing urethane paint is widely used.

However, it is difficult to improve the curability at room temperature and to secure a sufficient pot life, and it is strongly desired to improve both of them.

The inventors of the present invention have previously described (a) the general formula 3 to 50% by weight of a monomer having the structure (wherein R represents hydrogen or an alkyl group, and n represents an integer of 1 or 2), and an ethylenically unsaturated monomer copolymerizable with the above monomer. To 50% by weight of an isocyanate group-containing copolymer, and (b) a ketimine obtained by reacting a polyvalent amine compound containing two or more primary amino groups in one molecule with a ketone. We have invented a novel coating composition consisting of a compound and an enamine compound obtained by the reaction of a polyvalent amine compound containing two or more secondary amino groups in one molecule with an aldehyde or ketone.

However, the coating composition containing the above isocyanate copolymer solution or pigment absorbs moisture during long-term storage and slowly thickens, or water remaining when the ketimine compound or enamine compound of (b) is mixed. Therefore, the pot life tends to be shortened, and further improvement of these storability is desired.

The present invention, the isocyanate group-containing compound (a) and
(b) a resin composition comprising one or more ketimine compounds and enamine compounds, and (C) a general formula (R is hydrogen, an alkyl group or a phenyl group, and R ′ is an alkyl group).
The mixing ratio of the isocyanate group-containing copolymer of (b) and the ketimine compound and / or enamine compound of (b) is (a)
Of the isocyanate group of (b) and the amino group of the ketimine compound and / or the enamine compound of (b) (the sum of the amino group and the free amino group of the ketimine compound and / or the enamine compound) are 1: 0.6 to 1: 1.2. The mixing ratio of the orthoesters of (c) is relative to the solid content of (a) and (b).
A coating composition having an excellent storability of 0.5 to 20% by weight, wherein the component (c) can be added to the components (a) and / or (b) to control the thickening thereof. And
The pot life after mixing (a) and (b) can be extended.

As described above, the general formula used for the (a) isocyanate group-containing copolymer (In the formula, R is hydrogen or an alkyl group, and n is an integer of 1 or 2.)
Examples of the monomer having the structure of p-isopropenyl-α, α-dimethylbenzyl isocyanate, m-
Isopropenyl-α, α-dimethylbenzyl isocyanate, p-ethylenyl-α, α-dimethylbenzyl isocyanate, m-ethylenyl-α, α-dimethylbenzyl isocyanate, isopropenyl-α, α, α ',
Examples thereof include α′-tetramethylxylylene diisocyanate, ethylenyl-α, α, α ′, α′-tetramethylxylylene diisocyanate and the like. The ratio of these isocyanate group-containing monomers used in the copolymer is
3 to 50% by weight is suitable, and if it is less than 3% by weight, the crosslink density after curing of the composition is low and weather resistance and flexibility are not sufficient, so that it is not suitable. Is not appropriate because it is difficult to maintain In order to achieve the object of the present invention, the use ratio of the monomer is preferably 5 to 40% by weight, particularly preferably 10 to 30% by weight.

Examples of the ethylenically unsaturated monomer copolymerizable with the above monomers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, oleyl acrylate, Acrylic acid esters such as cyclohexyl acrylate and tetrahydrofurfuryl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate,
Butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate,
Methacrylic acid esters such as oleyl methacrylate, stearyl methacrylate, methoxyethyl methacrylate, butoxyethyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, tetrahydrofurfuryl methacrylate; styrene, α-methylstyrene, vinyltoluene, paramethyl Aromatic vinyl monomers such as styrene and chlorostyrene; Dialkyl esters of unsaturated dibasic acids such as maleic acid, fumaric acid and itaconic acid; Nitrile group-containing monomers such as acrylonitrile and methacrylonitrile; Vinyl acetate, One or more vinyl esters such as vinyl propionate are used. Of the above-mentioned ethylenically unsaturated monomers, acrylic acid esters and methacrylic acid esters are particularly preferable, and aromatic vinyl monomers and acrylic acid esters are used as the ethylenically unsaturated monomer. Or, in combination with methacrylic acid esters, the aromatic vinyl monomers are used in an amount of 0 to 30% by weight based on all monomers.
It is particularly preferable to use a nitrile group-containing monomer as an ethylenically unsaturated monomer and an acrylic acid ester, a methacrylic acid ester or an aromatic vinyl monomer as an ethylenically unsaturated monomer. It is particularly preferable to use the group-containing monomer in an amount of 5 to 30% by weight based on the total weight of the monomers, since the polymerization rate at the time of copolymer synthesis can be improved.

Isocyanate group-containing copolymer is usually 2,000 to 20,000
It has preferably a number average molecular weight of, in any of the solution polymerization method in the presence of a radical-generating polymerization initiator in an inert solvent, bulk polymerization method, suspension polymerization method and emulsion polymerization method. Although synthesizable, solution polymerization or bulk polymerization in the absence of water is particularly suitable for the intended use of the coating composition of the present invention.

(B) Reaction of at least one amino group of a polyvalent amine compound containing two or more primary amine groups in the messenger, which is another essential component of the coating composition of the present invention, with a ketone Ketimine compounds blocked by are, for example, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, nonamethylenediamine,
Aliphatic amines such as diethylenetriamine, isophoronediamine, 4,4'-diaminodicyclohexylmethane,
Aliphatic diamines such as 4,4′-diaminodicyclohexylpropane, hydrogenated xylylenediamine and dipentenediamine, amino groups such as α, α, α ′, α′-tetramethylxylylenediamine and xylylenediamine Can be obtained by dehydrating polyvalent amines such as diamines which are not directly bonded to an aromatic ring with ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and isophorone.
Aromatic amines such as methylenedianiline are not suitable as a raw material for the ketimine compound of the present invention because of their poor weather resistance. It is desirable that all amino groups of the polyvalent amine compound be ketiminated, but at least 1 in 1 child
If one amino group is ketiminated, it can be used in the present invention.

Used as a curing agent similar to the above ketimine compound,
Examples of the enamine compound obtained by the reaction of a polyvalent amine compound having two or more secondary amino groups in one molecule with an aldehyde or a ketone include N-unsubstituted piperazine and a structural formula. A secondary diamine represented by the formula (provided that R ¹ and R ^{2 in the} structural formula are
Is methyl, ethyl, n-propyl, i-propyl, n-
Butyl, sec-butyl, i-butyl, cyclopentyl, cyclohexyl, cyanoethyl group, etc., and A is a divalent alkyl, cycloalkyl, aryl, polyether group, etc.) and structural formula (Wherein A is a divalent alkyl, cycloalkyl, aryl, polyether group or the like in the structural formula, X is CH or N. When X is CH, A
A) and other polyvalent amines and acetaldehyde, propionaldehyde, n-butyraldehyde,
It can be obtained by dehydration reaction with aldehydes such as i-butyraldehyde and benzaldehyde, or acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, substituted cyclopentanone and ketones such as cyclohexanone and isophorone. .

In the enamine compound of the present invention, it is preferable that all secondary amino groups are enamined, but some amino groups may remain as amino groups.

The ketimine compound and the enamine compound may be used alone or in combination with the isocyanate group-containing copolymer (a), or may be used in combination.

The above (b) ketimine compound and enamine compound are latent amino compounds that release ketones and return to amines in the presence of water, and in a paint without water,
Although it does not react with the isocyanate group-containing copolymer of the above (a), when it is applied to the object to be coated, it absorbs moisture in the air to return to the amine, and immediately returns to the isocyanate group in the copolymer of the (a). Reacts with to form a strong cross-linked coating film.

The mixing ratio of the isocyanate group-containing copolymer of (a) and the ketimine compound and the enamine compound of (b) are the equivalent of the isocyanate group of (a) and the amino group (ketimine of the ketimine compound and the enamine compound of (b) (ketimine And enamine and the total of free amino groups) are mixed and used in a weight ratio such that the equivalent weight thereof is 1: 0.6 to 1: 1.2, particularly preferably 1: 0.7 to 1: 1.

The above general formula (C), A compound having a structure (wherein R is hydrogen, an alkyl group or a phenyl group, and R'is an alkyl group) is usually obtained by a condensation reaction of a compound having a structure of RCCl ₃ and an alcohol, and is commonly called an orthoester.

Examples of compounds having RCCl ₃ include chloroform, 1,1,1-trichloroethane, benzotrichloride and the like, and examples of alcohols include methanol, ethanol, isopropanol, n-propanol, n-butanol and isobutanol. is there.

The orthoesters of (C) are gradually reacted with moisture in the pigment or moisture from the outside during storage, decompose into ester compounds and alcohol compounds, and eliminate the moisture from the paint system, resulting in storability due to moisture. Prevent the decrease of.

The addition amount of the orthoester of the above (C), the above (a) and
Usually, 0.5 to 20% by weight based on the solid content of (b), preferably 1 to
It is 10% by weight.

The coating composition of the present invention, the components (a) and (b) are respectively stored and mixed before use for coating, but the orthoesters of the above (c) are the isocyanate groups of the above (a). It may be mixed in the containing copolymer or in the ketimine or enamine compound of the above (b), and it is particularly preferable to mix them in both.

That is, by mixing with the component (a) to prevent the isocyanate group of the component (a) from gradually reacting with water to thicken, and avoiding the accumulation of water and mixing the component (b) during use. It is possible to prevent a decrease in pot life. or,
The alcohol produced by the decomposition of (c) is less likely to reduce the effective isocyanate group content because the isocyanate group contained in (a) does not easily react with the alcohol, and is large when using other isocyanate-containing resins. There is a difference.

On the other hand, by mixing with component (b), it is possible to prevent the ketimine or enamine compound from returning to the amine during storage due to external moisture, and to prevent deterioration of the pot life when mixing (a) and (b). Can be done.

The coating composition of the present invention is usually used by dissolving it in water and an organic solvent containing no active hydrogen, and can be practically used as a transparent clear varnish, for example, titanium oxide, iron oxide, carbon black, phthalocyanine blue, etc. Inorganic fillers such as various coloring inorganic pigments and calcium carbonate, barium sulfate, talc, alumina, silica, glass fibers, bentonite, and further auxiliary agents such as leveling aids, defoaming aids, and dispersing aids It can be used for practical purposes by mixing and dispersing types.

As described above, the coating composition of the present invention has a significantly improved storage property and the cured coating film formed has excellent weather resistance and flexibility, and is formed of metal, wood, plastic, cement products or already formed. It can be widely used for organic coatings.

Hereinafter, the present invention will be specifically described with reference to examples.

Example 1 50 parts by weight of toluene was charged into a reactor and heated to 85 ° C., and then 20 parts by weight of m-isopropenyl-α, α-dimethylbenzyl isocyanate, 40 parts by weight of methyl methacrylate and 40 parts by weight of ethyl acrylate. A mixture of azobisisobutyronitrile and 2 parts by weight of azobisisobutyronitrile was added dropwise to toluene over 4 hours, the internal temperature was kept at 85 to 90 ° C., and 1 part by weight of azobisisobutyronitrile was added after completion of the addition. The mixture was further heated and stirred at the same temperature for 4 hours, and 50 parts by weight of ethyl acetate was added and diluted to prepare a solution of the isocyanate group-containing copolymer (I) of the present invention. Solid content 49.8%, viscosity 1200cps
(25 ° C), isocyanate group content 0.49 equivalent / 1000g
Met.

Example 2 Instead of the monomer mixture in Example 1, ethylenyl-
From 10 parts by weight of α, α, α ', α'-tetramethylxylylene diisocyanate, 20 parts by weight of styrene, 20 parts by weight of dibutyl fumarate, 50 parts by weight of n-butyl methacrylate and 2 parts by weight of azobisisobutyronitrile. Using this mixture, a solution of the isocyanate group-containing copolymer (II) of the present invention was produced in exactly the same manner as in Example 1.

The solid content was 50.0%, the viscosity was 950 cps (25 ° C.), and the isocyanate group content was 0.37 equivalent / 1000 g.

Example 3 Hexamethylenediamine 116 in reactor with water separator
By weight, 500 parts by weight of methyl isobutyl ketone were charged, and the mixture was heated and stirred at 115 to 120 ° C. for 8 hours, and the reaction was performed while separating and removing the produced water. The dehydration amount was 35 parts by weight.

After the reaction, 200 parts by weight of excess methyl isobutyl ketone was distilled off under reduced pressure, and 70 parts by weight of toluene was added to prepare a solution of the ketimine compound (A) which is the curing agent of the present invention. The effective amino group content in this solution was determined by acid titration.
It was 4.0 equivalent / 1000 g. The solid content was 61.0%.

Example 4 86 parts by weight of piperazine, 300 parts by weight of isobutyraldehyde and 200 parts by weight of toluene were added to a reactor equipped with a water separator, and heating was carried out at a reflux temperature to carry out a reaction for 10 hours while separating and distilling off only water produced. went. During this period, the reflux temperature gradually increased from 70 ° C. to 104 ° C., and the amount of separated water was 34 parts by weight. Further, 50 parts by weight of a mixture of isobutyraldehyde and toluene was distilled off under reduced pressure to prepare a solution of the enamine compound (B) which is the curing agent of the present invention. The content of effective amino groups in this solution was determined by acid titration to be 4.0 equivalents / 1000 g. Solid content is 42.7%
Met.

Example 5 50 parts by weight of titanium oxide, 15 parts by weight of toluene, and 1 part of ethyl acetate were added to 100 parts by weight of the solution of the isocyanate group-containing copolymers (I) and (II) of the present invention described in Examples 1 and 2, respectively.
5 parts by weight, 10 parts by weight of ethylene glycol monoethyl ether acetate, and 0.07 parts by weight of a silicon-based leveling agent were mixed and dispersed by a three-roll mill, and 19 parts by weight of this pigment dispersion was added with the stabilizer shown in Table 1. Addition and mixing of certain methyl osloformate or ethyl orthoacetate, paint base
(1) -The paint main agent (6) was adjusted. Initial viscosity of each paint and 4
The viscosity after storage at 0 ° C. for 1 month was measured by the Four Cup method, and the results are shown in Table 1.

Example 6 Ketimine compound which is the curing agent described in Examples 3 and 4
5 parts by weight of methyl orthoformate, which is a stabilizer, was added to 100 parts by weight of each of the solution of (A) and the solution of the enamine compound (B), and the mixture was stored at 40 ° C. for 1 month. Was used for the experiment.

Comparative Example 1 The pigment and dispersion prepared in Example 5 were stored in the same manner without adding a stabilizer, and the viscosity was measured. The results are shown in Table 1 (coating ingredients (7) and (8)). Further, the ketimine compound (A) solution and the enamine compound (B) solution were stored under the same conditions as in Example 6 without adding a stabilizer and subjected to the evaluation of the compounded paint shown in Comparative Example 2.

Example 7 40 parts of the stabilizer-containing coating base materials (1) to (6) described in Example 5
Stored for 1 month and two kinds of curing agents containing stabilizers described in Example 6 were mixed at the compounding ratios shown in Table 2, and toluene was further added to adjust the initial viscosity to about 30 seconds and the viscosity change by the Ford cup method. It was measured. In addition, each coating was applied to a zinc phosphate-treated cold-rolled steel sheet, allowed to stand at room temperature for 1 week, and then subjected to solvent resistance, impact resistance, and weather resistance tests by a weather ometer test. Rubbing test 50 times or more, impact resistance is DuPont impact test (500g
The gloss retention rate after irradiation under a load of 30 to 40 cm and the weather ometer for 500 hours was 90% or more, which was extremely good.

Comparative Example 2 The viscosity change of the compounded coating material was measured in the same manner as in Example 7 by using the coating material containing no stabilizer shown in Comparative Example 1 and the curing agent solution, and the results are shown in Table 2. Described.

Further, solvent resistance, impact resistance and weather resistance tests were carried out in the same manner as in Example 7, and the results were at the same level as in Example 7 and showed good results.

Claims (1)

[Claims] 1. (a) General formula 3 to 50% by weight of a monomer having a structure where R represents hydrogen or an alkyl group, and n represents an integer of 1 or 2, and an ethylenically unsaturated monomer copolymerizable with the above monomer. ~ 50% by weight
(B) a ketimine compound obtained by reacting a ketone with a polyvalent amine compound containing two or more primary amino groups per molecule, and an isocyanate group-containing copolymer obtained by copolymerizing One or more enamine compounds obtained by reacting a polyvalent amine compound containing two or more secondary amino groups with an aldehyde or ketone; and (c) the general formula (R is hydrogen, an alkyl group or a phenyl group, and R ′ is an alkyl group).
The mixing ratio of the isocyanate group-containing copolymer of (b) and the ketimine compound and / or enamine compound of (b) is (a)
Of the isocyanate group of (b) and the amino group of the ketimine compound and / or the enamine compound of (b) (the sum of the amino group and the free amino group of the ketimine compound and / or the enamine compound) are 1: 0.6 to 1: 1.2. The mixing ratio of the orthoesters of (c) is relative to the solid content of (a) and (b).
A coating composition having an excellent storability of 0.5 to 20% by weight.