JPS6318967B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a curable composition that has high surface hardness, flexibility, and excellent water resistance, chemical resistance, and heat resistance, and particularly has good adhesion to a base material (for example, a steel plate). It is suitable for use as a high-performance baking paint. Conventionally, alkyd resins used as baking-type coating compositions generally have a large number of hydroxyl groups as reactive groups and have as low an acid value as possible, and melamine formaldehyde resins and modified resins thereof are used as crosslinking agents. is used. However, when melamine formaldehyde resin or the like is used as a crosslinking agent, formaldehyde, which is harmful and has an irritating odor, is generated during baking, which is undesirable in terms of work and environmental hygiene, and causes various problems. A coating composition that does not generate such formaldehyde and provides a coating film having excellent water resistance, chemical resistance, surface hardness, heat resistance, etc. is desired. The present inventors have investigated coating compositions that do not generate formaldehyde, which has a harmful and irritating odor as described above, and which provide a coating film with sufficiently excellent coating performance. 2
A high acid value alkyd resin having a free carboxyl group at the side chain or end of the molecule in a mixture or reaction product consisting of a polyfunctional cyanate ester having at least three cyanate groups and a bismaleimide or trismaleimide; Alternatively, by combining these modified resins, there is no generation of formaldehyde, which has a harmful and pungent odor, and the hardness is high.
The present invention was accomplished by discovering that a film with high flexibility, adhesion, heat resistance, etc. can be obtained. That is, the present invention provides (a) a polyfunctional cyanate ester, a prepolymer of the cyanate ester, or a prepolymer of the cyanate ester and an amine, and (b) bismaleimide, trismaleimide, a prepolymer of the maleimide, or the maleimide. It is a curable resin composition consisting of a mixture or reactant of an amine with a prepolymer and () a high acid value type alkyd resin with an acid value of 20 to 150. The polyfunctional cyanate ester of component (a) of the present invention is an organic cyanate ester represented by the following general formula having at least two or more cyanate groups in the molecule. Formula R(OC≡N)m (wherein, R is a residue having an aromatic nucleus derived from an aromatic hydrocarbon selected from the group consisting of benzene, biphenyl, and naphthalene; two or more benzene rings

[Formula] (R ₁ and R ₂ may be the same or different and are hydrogen or an alkyl group having 1 to 4 carbon atoms), -
O-, _{-CH2OCH2- ,} -S-,

【formula】

【formula】 【formula】

[Formula] and

A residue having an aromatic nucleus derived from a compound bonded by a bridge selected from the group consisting of [Formula]; aroma obtained by removing the phenolic hydroxyl group from a novolak type or resol type phenolic resin skeleton The residue is selected from a residue having a nucleus; a residue having an aromatic nucleus obtained by removing the terminal hydroxyl group of a polycarbonate skeleton derived from bisphenol. These aromatic nuclei may be substituted with an alkyl group having 1 to 4 carbon atoms, an alkoxy group, chloro, or bromine substituent. m is 2
~10, and the cyanate group is always bonded directly to the aromatic nucleus. ) Specific examples of such compounds include 1,
3- or 1,4-dicyanatobenzene, 1,
3,5-tricyanatobenzene, 1,3-,
1,4-, 1,6-, 1,8-, 2,6- or 2,7-dicyanatonaphthalene, 1,3,6-
Tricyanatonaphthalene, 4,4'-dicyanatobiphenyl, bis(4-cyanatophenyl)
Methane, 2,2-bis(4-cyanatophenyl)propane, 2,2-bis(3,5-dichloro-4-cyanatophenyl)propane, 2,2-
Bis(3,5-dibromo-4-dianatophenyl)propane, bis(4-cyanatophenyl)
ether, bis(4-cyanatophenyl) thioether, bis(4-cyanatophenyl) sulfone, tris(4-cyanatophenyl) phosphite, tris(4-cyanatophenyl) phosphate, and the like. In addition to these, cyanic acid esters described in Japanese Patent Publication No. 46-4112 or Japanese Patent Publication No. 44-4791 can be used. In addition, the molecular weight of these cyanate esters has a triazine ring formed by trimerization of the cyanate group.
400-6000 prepolymers are also used. This prepolymer can contain the above-mentioned cyanate esters, for example, mineral acids, Lewis acids, and other acids; sodium hydroxide;
It can be obtained by polymerization using a base such as sodium alcoholate or tertiary amines; or a salt such as sodium carbonate or lithium chloride as a catalyst. Polyfunctional cyanate esters can also be used in the form of mixtures of monomers and prepolymers. For example, many of the commercially available cyanate esters from bisphenol A and cyanogen halides may be in the form of mixtures of cyanate ester monomers and prepolymers; such raw materials It can be fully used for the purpose of the present invention. Furthermore, as described later, reactants with amines are also suitably used. The bismaleimide or trismaleimide of component ()b used in the present invention is any organic compound having two or three maleimide groups derived from maleic anhydride and a polyvalent amine, and
Bismaleimide or trismaleimide that can be suitably used in the present invention has the following general formula: (In the formula, R is a divalent or trivalent aromatic or alicyclic organic group, X ¹ and X ² are hydrogen, halogen, or an alkyl group, and n is 2 or 3.) expressed. Maleimides represented by the above formula can be produced by a method known per se, in which maleic anhydride and divalent or trivalent amines are reacted to prepare maleamic acid, and then maleamic acid is cyclodehydrated. . The polyvalent amines used are preferably aromatic amines in terms of the heat resistance of the final resin, but if flexibility and flexibility of the resin are desired, alicyclic amines may be used alone or in combination. It's okay. In addition, it is particularly desirable that the polyvalent amines be primary amines in terms of reactivity, but secondary
It is also possible to use grade amines. These maleimides can be used alone or in combination of two or more. Moreover, those obtained by heating without a catalyst or in the presence of a catalyst to form a prepolymer can also be suitably used. Furthermore, the polyfunctional cyanate ester and bismaleimide or trismaleimide each modified with an amine can also be used. These amines include metaphenylenediamine,
Meta- or para-xylylenediamine, 1,4-cyclohexanediamine, hexahydroxylylenediamine, 4,4'-bisaminophenylmethane,
4,4′-bisaminophenyl sulfone, bis(4
-amino-3-methylphenyl)methane (MDT), bis(4-amino-3,5-dimethylphenyl)methane (MDX), 4,4'-bisaminophenylcyclohexane, 4,4'-bisaminophenyl enyl ether, 2,2-bis(4'-aminophenyl)propane, 2,2-bis(4-amino-3
-methylphenyl)methane, α,α-bis(4-
Examples include aminophenyl) phenylmethane. The composition ratio of a and b in the component () of the present invention described above is not particularly limited, but it is preferably in the range of 20:80 to 95:5 in weight ratio of a and b. The high acid value type alkyd resin as component () in the composition of the present invention has an average molecular weight of 500 to 3000, and has an acid value of
20-150, preferably 40-100 are used. Conventional methods for obtaining high acid value type alkyd resins are applied to such alkyd resins, but one or more polyhydric carboxylic acids and one or more polyhydric alcohols are mixed with an acid in an excess amount of polyhydric alcohol. The desired high acid value type alkyd resin can be easily produced by a stepwise reaction method, such as reacting until the value is 20 or less, and then reacting with a polyfunctional polycarboxylic acid (for example, trimellitic anhydride). This is a preferred method because it can be synthesized into The polyhydric carboxylic acids and polyhydric alcohols used in the production of the above-mentioned alkyd resins are those used in the production of conventional alkyd resins, and the polyhydric carboxylic acids include, for example, phthalic anhydride, isophthalic acid, terephthalic acid, or lower alkyl esters thereof, tetrahydrophthalic anhydride,
Hexahydrophthalic anhydride, tetrabromo phthalic anhydride, tetrachlorophthalic anhydride, hexic anhydride, 3,6-endomethylene-△ ⁴ phthalic anhydride,
maleic anhydride, tetrahydromaleic anhydride,
Divalent carboxylic acids such as fumaric acid, itaconic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, trivalent carboxylic acids such as trimellitic anhydride, trimellitic acid, methylcyclohexenetricarboxylic acid, pyromellitic anhydride Examples include acids. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-butylene glycol,
Dihydric alcohols such as 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, trihydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, trishydroxymethylaminomethane, pentaerythritol, dipentaerythritol,
etc. are exemplified. Additionally, in some cases, oils such as linseed oil, tung oil, dehydrated castor oil, soybean oil, safflower oil, coconut oil, and castor oil, and fatty acids such as linseed oil fatty acids, coconut oil fatty acids, tall oil fatty acids, etc. It can also be used for oil modification. In addition, modified alkyd resins modified with rosin, phenols, epoxy compounds, vinyl compounds, etc. can also be used. Furthermore, as described above, the alkyd resin used in the present invention is a high acid value type alkyd resin with an acid value of 20 to 150, unlike ordinary alkyd resins, but the alkyd resin has free hydroxyl groups. In other words, it is almost impossible to reduce the hydroxyl value to zero, and it is desirable that the hydroxyl value of the high acid value type alkyd resin used in the present invention is 50 or less, and more preferably 40. It is more preferable that it is the following. The composition ratio of the above-mentioned components () and () in the present invention is not particularly limited, and the weight ratio is 1:
In the range of 99-99:1, preferably 5:95-95:5
It can be used within the following range, and the use of the composition,
The most suitable combination of raw materials and composition ratios for the purpose of use and for imparting suitable coating performance can be determined as appropriate, such as using more component () if higher heat resistance is required. selected. When coating a substrate (for example, a steel plate) with the composition of the present invention, it is applied by a known method such as spraying, dipping, or brushing. These painting methods,
Alternatively, the coating viscosity is generally adjusted to an appropriate coating viscosity using a diluting solvent, although this varies depending on the purpose. Examples of the diluting solvent include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, ethyl acetoacetate, butyl acetoacetate,
Examples include keto-enol type tautomeric compounds such as acetylacetone, diacetone alcohol, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether acetate, and mineral spirits. Used as a mixture of more than one species. Among these diluting solvents, ethyl acetoacetate is particularly preferred. In addition, the resin composition of the present invention itself has the property of becoming a heat-resistant resin by being bonded and reticulated by heating, but for the purpose of promoting crosslinking and reticulation as described above,
A catalyst can be included in the composition. Such catalysts include organic bases such as N,N-
Dimethylaniline, N,N-dimethyltoluidine, N,N-dimethyl-p-anisidine, P-halogeno-N,N-dimethylaniline, 2-N-ethylanilinoethanol, tri-n-butylamine, pyridine, quinoline, Tertiary amines such as N-methylmorpholine and triethanolamine;
Imidazoles such as imidazole and benzimidazole; Phenols such as phenol, cresol, xylenol, resorcinol, and phloroglucin; Organic metal salts such as lead naphthenate, lead stearate, zinc naphthenate, tin oleate, dibutyltin maleate, naphthenic acid Manganese, cobalt naphthenate, lead resinate, SnCl ₄ , ZnCl ₂ , AlCl ₃
Chlorides, etc., are suitable. The amount of these catalysts varies significantly depending on the type of catalyst, use, curing conditions, etc., and cannot be unconditionally defined, but in a general sense, the amount of catalyst, for example, 5% based on the total resin solid component.
It is preferable to use it in an amount of % by weight or less. The curable resin composition of the present invention may also contain pigments, fillers, flame retardants, coating film, etc., as desired, for the purpose of improving the properties of the resin in the final coating film, adhesive layer, resin molded product, etc. Additives such as modifiers and various natural, semi-synthetic or synthetic resins can be blended. For example, an epoxy compound may be used to further increase adhesiveness, or a synthetic mica may be used to increase flexibility. The curable resin composition of the present invention is particularly suitable as a coating material, and examples of the substrate in this case include ceramics, thermosetting resins, and metals. Curing is usually 80-300℃, preferably 100-250℃
There are methods of curing by heating at a temperature of °C and other methods using light. The curable resin composition of the present invention as described above provides a coating film with high heat resistance, high surface hardness, and excellent flexibility, water resistance, chemical resistance, etc., especially when used as a paint. It is suitable for use as a high-performance baking paint. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the examples, "part" indicates part by weight, and "%" indicates weight %. Example 1 348 parts of neopentyl glycol, 112 parts of trimethylolpropane, 489 parts of isophthalic acid, and 143 parts of adipic acid were placed in a reactor equipped with a thermometer, thermocouple, stirring bar, nitrogen gas inlet, and condenser for taking out condensed water.
The temperature inside the reactor was gradually raised under a nitrogen gas flow. After raising the temperature to 240°C, react at the same temperature under a nitrogen gas atmosphere, and when the acid value of the reactant reaches 20 or less, lower the temperature inside the container to 180°C or less, and then add 44 parts of trimellitic anhydride. After adding trimellitic anhydride, react again at 180℃ for about 30 minutes,
An oil-free alkyd resin having a resin acid value of 40-45 was obtained. This resin had a number average molecular weight of 1840 as measured by vapor pressure method. The resin was diluted with ethylene glycol monomethyl ether to a solid concentration of 70% to obtain a varnish having a Gardner bubble viscosity of Z ₄ -Z ₅ and a Gardner color number of 2. Next, for 80 parts of the solid content of the alkyd resin, 2,2
-After adding 20 parts of bis(4-cyanatophenyl)propane and 20 parts of bis(4-maleimidophenyl)methane, diluted with 134 parts of ethyl acetoacetate,
Viscosity is 19 seconds in food cup #4, non-volatile content is 38%
obtained a transparent varnish. This varnish is applied to Bonterite #144 treated steel plate (0.5
mm thickness) and aluminum foil, respectively.
After spray painting to 20-30, 160
After baking at ℃ for 20 minutes, a smooth coating film with a good appearance was obtained. The coating performance is shown in Table 1. Example 2 (A) Using a reactor similar to that used in Example 1, 391 parts of neopentyl glycol, 114 parts of isophthalic acid, 100 parts of adipic acid, and 225 parts of trimellitic anhydride were charged and heated under a nitrogen gas stream. Raise the temperature inside the reactor to 220°C. Approximately 30 at this temperature
The reaction was allowed to proceed for several minutes, and when the resin acid value reached 95, the reaction was stopped and the temperature was lowered. (B) Separately, use another reactor, charge it with 127 parts of isopropyl alcohol, and raise the temperature inside the reactor to 80°C under a nitrogen gas stream. To this, 69 parts of methyl methacrylate, 131 parts of butyl acrylate, 12 parts of diethylaminoethyl methacrylate, 32 parts of acrylic acid, 5 parts of azobisisobutyronitrile, n
- A mixture consisting of 5 parts of dodecyl mercabutane was added dropwise from a dropping funnel over a period of 3 hours, and the temperature was 80°C.
The mixture was allowed to react for 4 hours. The alkyd resin synthesized in (A) and the acrylic resin synthesized in (B) were charged into a reactor equipped with a thermometer, thermocouple, stirring rod, nitrogen gas inlet, and cooler, and gradually heated under a nitrogen gas stream. The solvent and produced water are removed. The temperature was raised to 180°C, and the reaction was carried out at this temperature until the resin acid value reached 55 to obtain an acrylic modified alkyd resin. The average molecular weight of this resin was 1600 as measured by vapor pressure method. The obtained acrylic modified alkyd resin was diluted with ethylene glycol monomethyl ether to a solid content of 70%, and the final resin acid value was 53 and the viscosity was Z ₄ ~
A liquid resin of Z ₅ and 3 colors was obtained. Next, to 80 parts (solid content) of the acrylic modified alkyd resin, 20 parts (solid content) of the same cyanate ester and 20 parts (solid content) of bismaleimide as used in Example 1 were added, and then acetate was added. It was diluted with a mixed solvent consisting of 120 parts of ethyl acetate and 40 parts of xylene to obtain a transparent varnish with a viscosity of 18 seconds in a #4 food cup and a non-volatile content of 40%. This varnish was applied to a steel plate in the same manner as in Example 1, and baked under the same conditions as in Example 1. The coating performance is shown in Table 1. Example 3 Solid content of alkyd resin obtained in Example 1: 83
7 parts (solid content) of 2,2-bis(4-cyanatophenyl)propane, 8 parts of bis(4-maleimidophenyl)methane, and 4-maleimidophenyl-3',4'-di A coating film was obtained in the same manner as in Example 1, except that 2 parts of a mixture of maleimidophenylmethane and 4-maleimidophenyl-2',4'-dimaleimidophenylmethane were added. The coating performance is shown in Table 1. Comparative Example 1 Using a reactor similar to that used in Example 1, 563 parts of neopentyl glycol, 363 parts of trimethylolpropane, 419 parts of adipic acid, and 637 parts of phthalic anhydride were charged, and the mixture was gradually heated under a stream of nitrogen gas. The temperature was raised to 240°C and maintained at 240°C. After reacting at 240°C for about 10 hours, a resin with an acid value of 10 was obtained. The reaction was stopped, and after the temperature was lowered, the mixture was diluted with a mixed solvent of xylene/butyl cellosolve=9/1 (weight ratio) so that the nonvolatile content was 65%. The obtained alkyd resin has a viscosity (Gardner bubble viscosity) UV, a color number (Gardner) 2,
The number average molecular weight was 1480 (VPO), the acid value was 10 (solid content), and the hydroxyl value was 137. Next, 20 parts of the same cyanate ester and 20 parts of bismaleimide as used in Example 1 were added to 80 parts of the obtained hydroxyl group-containing alkyd resin solid content, and then
Dilution with 120 parts of ethyl acetoacetate and 26 parts of dimethylformamide gave a varnish. Baking conditions: 140℃ for 20 minutes (A) or 160℃
A baked coating film was formed under the same conditions as in Example 1 except for 20 minutes (B). The coating performance is shown in Table 1.

[Table] *1 Pencil hardness tester *2 Dupont impact tester *3 % extraction residue after immersing the peeled film in a large excess of acetone and boiling it for 7 hours
Example 4 20 parts of the high acid value type acrylic modified alkyd resin obtained in Example 2 as solid content, 2,2-bis(4-
After adding 40 parts of cyanatophenyl)propane, 60 parts of bis(4-maleimidophenyl)methane, and 0.05 part of zinc octylate and 1 part of dimethylbenzylamine as a catalyst, 60 parts of ethyl acetoacetate and 100 parts of N,N-dimethylformamide. A varnish was obtained by diluting it with 50%. This varnish was applied to the same steel plate and aluminum foil as in Example 2 to a coating thickness of 20 to 30 μm, and then baked at 180° C. for 30 minutes to obtain a smooth coating with a good appearance. The coating hardness was 6H. Others are cross cut 100/100, 2mmφ bent A,
1/2 inch α500g impact value was 20cm.

Claims (1)

[Scope of Claims] 1 ()a A polyfunctional cyanate ester, a prepolymer of the cyanate ester, or a prepolymer of the cyanate ester and an amine, and b bismaleimide or trismaleimide, a prepolymer of the maleimide, or A curable resin composition comprising a mixture or reactant of a prepolymer of maleimide and an amine, and () a high acid value alkyd resin having an acid value of 20 to 150.