JP2609881C - - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a curable resin composition and a method for curing the same. 2. Description of the Related Art Conventionally, when a resin having an unsaturated group is cured by heating, it is generally performed to add a radical polymerization catalyst or a polythiol to cause a radical addition polymerization reaction to crosslink the resin. ing. However, this method has the drawbacks that the storage stability of the curable resin composition is poor and that the curing of the resin surface is prevented by oxygen in the air. As an alternative to the above method, a method in which a compound having active hydrogen is reacted with a polymerizable unsaturated group by Michael addition in the presence of a basic catalyst to cure the compound has been developed. The storage stability of the cured product is poor, and the basic catalyst remains in the cured product to lower the water resistance of the cured product. Means for Solving the Problems An object of the present invention is to provide a curable resin composition free from the above-mentioned disadvantages, that is, it has excellent storage stability, good curability, and excellent water resistance. And a method of curing the resin composition. According to the present invention, (a) selected from the group consisting of acrylic resins, polyester resins and epoxy resins.
Barre was, resins having a polymerizable unsaturated group in the molecule, and (b) the following formula in the molecule (I) [In the formula, R ₁ represents a hydroxyl group, an alkoxy group, an ester group, a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a hydrogen atom. And Y represents a sulfur atom. R ₂ , R ₃ and R ₄ are the same or different and have 1 to 1 carbon atoms.
And 14 organic groups. Further, R ₂ and R ₃ or R ₂ , R ₃ and R ₄ may be taken together to form a heterocyclic group together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. A curable resin composition containing a resin having an aprotic onium salt-containing group represented by the formula: and a resin composition characterized by heating and curing the resin composition at 80 ° C or higher. A curing method is provided. The curable resin composition of the present invention comprises a resin having a polymerizable unsaturated group in a molecule (hereinafter, also referred to as “resin (a)”) and a resin having the specific aprotic onium salt-containing group ( Hereinafter, it may be referred to as “resin (b)”). Examples of the resin having a polymerizable unsaturated group, does not contain at least one content to and above onium salt-containing group in the molecule a polymerizable unsaturated group, acrylic resin
, A polyester resin and an epoxy resin.
In the present invention, a resin having a primary hydroxyl group is preferable from the viewpoint of curability. Also, the molecular weight of the resin is not particularly limited, but preferably has a peak molecular weight of about 250 to 100,000, more preferably about 500 to 20,000 according to gel permeation chromatography (GPC). If the molecular weight of the resin exceeds the above range, coating workability tends to decrease, which is not preferable. Examples of the polymerizable unsaturated group include, for example, acryloyl, methacryloyl, itaconate, maleate, fumarate, crotonate, acrylamide, methacrylamide, cinnamic acid, vinyl, allyl, and drying oil fatty acids. saturated group, and the like. The polymerizable unsaturated group is required to be at least one per molecule, and is preferably in the range of 0.1 to 10 mol per 1 kg of resin solid content from the viewpoint of curability,
More preferably, it is in the range of 5 moles. When the amount is less than 0.1 mol, the curing of the resin becomes insufficient. On the other hand, when the amount is more than 10 mol, the mechanical properties of the cured product tend to decrease. Introduction of a polymerizable unsaturated group into the resin can be performed by employing a conventionally known means. For example, (i) an addition reaction between a carboxyl group and an epoxy group, (ii)
(Iii) an esterification reaction between a hydroxyl group and a carboxyl group, (iv) an addition reaction between an isocyanate group and a hydroxyl group, (v) a half esterification reaction between a hydroxyl group and an acid anhydride, (vi ) It can be carried out by utilizing a transesterification reaction between a hydroxyl group and an ester group or the like, and using a compound having a polymerizable unsaturated group in one or both of the compound or resin having such a functional group. Further, as the resin having the onium salt-containing group, as long as it is a resin containing at least one onium salt-containing group in a molecule, an acrylic, polyester, urethane, polybutadiene, alkyd, epoxy, phenol, or phenol Any known resin such as a resin may be used, and the resin is not particularly limited, but a resin having good compatibility with the resin (a) is preferable. In the present invention, a resin having a primary hydroxyl group is preferable from the viewpoint of curability. The molecular weight of the resin is also not particularly limited, but preferably has a peak molecular weight of about 150 to 100000 by GPC,
Those having about 200 to 20,000 are more preferable. If the molecular weight of the resin exceeds the above range, coating workability tends to decrease, which is not preferable. The aprotic onium salt-containing group is represented by the above formula (I), and is a group having a secondary hydroxyl group in which the carbon atom at the β-position from the nitrogen, phosphorus or sulfur atom of the onium salt has a secondary hydroxyl group. It is necessary. Such an aprotic onium salt is any of a quaternary ammonium salt, a quaternary phosphonium salt and a tertiary sulfonium salt. Specific examples of the cation in the aprotic onium salt-containing group are shown below. [In each of the above formulas, R ₂ , R ₃ and R ₄ are the same or different and each have 1 to 14 carbon atoms.
Represents an organic group. And R ₂ and R ₃ or R ₂ , R ₃ and R ₄ together
A heterocyclic group may be formed together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. The organic group having 1 to 14 carbon atoms represented by R ₂ , R ₃ and R ₄ is not particularly limited as long as it does not substantially interfere with ionization of an ammonium base, a phosphonium base or a sulfonium base, For example, a hydrocarbon group having 1 to 14 carbon atoms which may contain a hetero atom such as an oxygen atom in the form of a hydroxyl group, an alkoxy group or the like is generally used. Examples of such a hydrocarbon group include an aliphatic, alicyclic or aromatic hydrocarbon group such as an alkyl group, a cycloalkyl group, a cycloalkylalkyl group, an aryl group and an aralkyl group. The alkyl group may be linear or branched, and preferably has a carbon number of 8 or less, preferably a lower one. For example, methyl, ethyl, n- or iso-propyl, n- , Iso-, sec- or tert-butyl, pentyl, heptyl and octyl groups. The cycloalkyl group or cycloalkylalkyl group preferably has 5 to 8 carbon atoms, and examples thereof include cyclopentyl, cyclohexyl, cyclohexylmethyl, and cyclohexylethyl. The aryl group includes a phenyl, toluyl, xylyl group and the like. A benzyl group is preferred as the aralkyl group. Preferred examples of the hydrocarbon group containing a hetero atom, for example, an oxygen atom include a hydroxyalkyl group (particularly, a hydroxy lower alkyl group), specifically, hydroxymethyl, hydroxyethyl, hydroxybutyl, hydroxypentyl,
Hydroxyheptyl, hydroxyoctyl group and the like, and alkoxyalkyl group (especially lower alkoxy lower alkyl group), specifically methoxymethyl, ethoxymethyl, ethoxyethyl, n-propoxyethyl, iso-propoxymethyl, n-butoxymethyl, iso -Butoxyethyl, tert-butoxyethyl group and the like. R ₂ and R ₃ or R ₂ , R ₃ and R ₄ together form the nitrogen atom to which they are attached. For example, the following can be exemplified. Further, as the hydroxyl group, alkoxy group, ester group or hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a halogen atom represented by R ₁ in the above formula (I),
Examples thereof include an aliphatic, alicyclic or aromatic hydrocarbon group such as an alkyl group, an alkenyl group, a cycloalkyl group, a cycloalkylalkyl group, an aryl group and an aralkyl group. Among these, an alkyl group and an alkenyl group are preferable, and these groups may be either linear or branched, and particularly preferably a lower one, for example, methyl, ethyl, n- or iso-propyl. , N-, iso-, sec- or tert-
Examples include butyl, pentyl, heptyl, octyl, vinyl, and 2-methylvinyl groups. Preferred examples of the hydroxyl-substituted hydrocarbon group include a hydroxyalkyl group (
Particularly, a hydroxy lower alkyl group), specifically, a hydroxymethyl, hydroxyethyl, hydroxybutyl, hydroxypentyl, hydroxyheptyl, hydroxyoctyl group and the like. Preferred examples of the alkoxy-substituted hydrocarbon group include an alkoxyalkyl group (especially a lower alkoxy lower alkyl group), specifically methoxymethyl, ethoxymethyl, ethoxyethyl, n-propoxyethyl, iso-propoxymethyl, n-butoxy. Methyl, iso-butoxyethyl, tert-butoxyethyl and the like. Preferred examples of the ester group-substituted hydrocarbon group include a lower alkoxycarbonylalkyl group, a lower alkoxycarbonylalkenyl group and the like, specifically, methoxycarbonylmethyl, propoxycarbonylethyl, ethoxycarbonylpropyl, methoxycarbonylbutyl, methoxycarbonylethylenyl, An ethoxycarbonylethylenyl group is exemplified. Preferred examples of the halogen atom-substituted hydrocarbon group include chloromethyl, bromomethyl, iodomethyl, dichloromethyl, trichloromethyl, chloroethyl, chlorobutyl and the like. Further, the aprotic onium salt-containing group is used in an amount of 0.01 to 5 per kg of resin solid content.
It is preferably in the range of moles, more preferably in the range of 0.1 to 2 moles. If the amount is less than 0.01 mol, curing tends to be insufficient, which is not preferable. Conversely, if the amount exceeds 5 mol, the water resistance of the cured product obtained by curing may decrease, which is not preferable. The onium salt can be introduced into the resin according to, for example, the method shown in the following (A) or (B). (A) A tertiary amine, phosphine or thioether is reacted with a resin having a 2-halogeno-1-hydroxyethyl group in a water-miscible inert organic solvent, and then a halogen atom is converted to a hydroxyl group by anion exchange. Substituting and then reacting with an organic acid. Taking a case where a tertiary amine is used as a compound to be reacted with the above resin as an example, the reaction formula is as follows. R ₄ is the same as above. When phosphine is used instead of the tertiary amine, N may be replaced with P in the above reaction formula, and when thioether is used instead of the tertiary amine, N is replaced with S in the above reaction formula. replaced and -R ₄ may be deleted to. The reaction between the resin and a tertiary amine or the like is performed under heating at about 100 to 150 ° C., and the reaction is completed in about 1 to 20 hours. In order to replace a halogen atom with a hydroxyl group, a resin to be treated may be passed through a usual anion exchange resin such as a bead type anion exchange resin. The reaction between the thus-obtained hydroxyl-substituted resin and the organic acid easily proceeds simply by mixing the two at room temperature. (B) A method in which a tertiary amine, phosphine or thioether and an organic acid are simultaneously reacted with a resin having a 1,2-epoxy group in a water-miscible inert organic solvent. Taking a case where a tertiary amine is used as a compound to be reacted with the above resin as an example, the reaction formula is as follows. When phosphine is used in place of the tertiary amine and thioether is used in place of the tertiary amine, N is converted to P in the above reaction formula as in the case of (A).
, Or replace N with S and delete -R ₄ . The reaction between the resin, the tertiary amine and the like and the organic acid is carried out under heating at about 40 to 80 ° C., and the reaction is completed in about 1 to 20 hours. Examples of the water-miscible inert organic solvent used in the above (A) and (B) include, for example, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethanol, propanol, butanol and the like. And the like. The organic acid is an organic carboxylic acid that forms an anion in which R ₁ in the above formula (I) represents a hydroxyl group, an alkoxy group, an ester group, or a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a halogen atom. Can be widely used as long as it is, specifically, acetic acid, formic acid, trimethylacetic acid, acrylic acid, methacrylic acid, lactic acid, hydroxyacetic acid, crotonic acid, chloroacetic acid, monomethyl maleate, monoethyl fumarate Esters and itaconic acid monomethyl ester are exemplified. Among them, those having a dissociation constant (pKa value) of 1 × 10 ⁻⁵ or more are particularly preferable. When the resin is an acrylic resin, the onium salt can be introduced into the resin according to the methods (A) and (B) described above. [Wherein R ₅ represents a hydrogen atom or a methyl group. R ₁ and W are the same as above. Can be carried out by polymerizing the (meth) acrylic acid ester monomer represented by the formula (1) alone or together with a comonomer copolymerizable therewith in a conventional manner. Further, the resin (b) in the present invention may have a polymerizable unsaturated group in the molecule, and the amount of the polymerizable unsaturated group depends on the solidity of the resin (b) from the viewpoint of the physical properties of the obtained cured product. 1 kg per minute
It is preferably 10 mol or less per mol. The introduction of the polymerizable unsaturated group into the resin (b) can be performed in the same manner as the introduction of the polymerizable unsaturated group into the resin (a). The compounding ratio of the resin (a) and the resin (b) in the present invention is a solid content weight ratio, the resin (a)
Is preferably 99.99% by weight or less, more preferably 99.9% by weight or less. Furthermore, when the resin (b) has less than 0.1 mol of polymerizable unsaturated groups per 1 kg of solid content or has no polymerizable unsaturated group, the resin (a)
) Is preferably in the range of 99.99 to 50% by weight, more preferably in the range of 99.9 to 70% by weight, and the resin (b) is preferably in the range of 0.01 to 50% by weight, and 0.1 to 3% by weight.
A range of 0% by weight is more preferred. The resin composition of the present invention containing the resin (a) and the resin (b) further includes a coloring pigment,
Various additives such as extenders, rust preventive pigments, dyes, and other leveling agents, defoamers, and anti-sagging agents may be blended. The resin composition of the present invention is used in a form dissolved or dispersed in an organic solvent, or using a water-miscible solvent as a solvent at the time of preparing the resin, adding water to the obtained resin liquid, Alternatively, it is used in the form of an aqueous solution or an aqueous dispersion by being mixed in water. When curing the resin composition of the present invention, for example, a solution or dispersion of the resin composition, spray coating, brush coating, roll coating, dip coating and the like are applied to an object to be coated, and this is applied. Heat treatment may be performed at a temperature of 80 ° C. or higher, preferably 100 ° C. or higher, more preferably about 120 to 200 ° C., preferably 5 minutes or longer, more preferably about 10 to 30 minutes. Although the curing reaction mechanism in this case is not clear, the disappearance of the unsaturated group is observed in the change of the infrared absorption spectrum, so the polymerization of the polymerizable unsaturated group or the active hydrogen such as a hydroxyl group to the polymerizable unsaturated group is performed. This is probably due to the addition reaction. In addition to the curing reaction, Hoffman decomposition of the onium salt in the resin occurs in addition to the curing reaction, and as a result, excellent water resistance can be imparted to the cured product. In the present invention, in the present invention, a specific aprotic onium salt contained in the resin acts as a catalyst at the time of crosslinking and curing of the resin, and Hoffman decomposition easily occurs during or after crosslinking of the resin, The onium salt is no longer contained in the cured product, and as a result, an excellent effect of preventing a decrease in water resistance of the cured product is exhibited. Therefore,
The resin composition of the present invention has excellent storage stability and curability. Further, according to the method of the present invention, a cured product having excellent water resistance can be obtained. The resin composition of the present invention can be suitably used, for example, as a low-temperature curing type paint. Examples The present invention will be further clarified with reference to the following examples. In addition, simply "part" and "
"%" Means "parts by weight" and "% by weight", respectively. Production Example 1 of Resin (a) Having Polymerizable Unsaturation Group Production Example 1 Epicoat # 154 (manufactured by Ciel Chemical Co., Ltd.) 627 parts, ethylene glycol monobutyl ether 883 parts, acrylic acid 252 parts, hydroquinone 1 part, and tetraethylammonium bromide 3 parts In a four-necked flask,
The reaction was carried out at a temperature of 6 ° C. for 6 hours, and the point where the acid value became 3 or less was regarded as the end point. The obtained resin liquid (hereinafter, this resin liquid is referred to as “resin liquid (1-A)”) had a nonvolatile content of 49.5% and a Gardner viscosity (25 ° C.) of K. The peak molecular weight of this resin by GPC was about 900. Production Example 2 116 parts of 2-hydroxyethyl acrylate, glycidyl methacrylate 28
4 parts, n-butyl methacrylate 600 parts and azobisisobutyronitrile 30
Of the mixture was added to a four-necked flask containing 1000 parts of n-butyl alcohol maintained at 130 ° C. over 3 hours to carry out polymerization. Thereafter, the mixture was cooled to 110 ° C., and 172 parts of methacrylic acid, 1 part of hydroquinone and 2 parts of tetraethylammonium chloride were added and reacted until the acid value became 3 or less. The obtained resin solution (hereinafter, this resin solution is referred to as “resin solution (2-A)”) has a nonvolatile content of 54.
0% and Gardner viscosity (25 ° C.) was Q. The peak molecular weight of this resin by GPC was about 10,000. Production Example 3 A mixture of 650 parts of itaconic acid and 248 parts of ethylene glycol was dehydrated and condensed at 220 ° C. to synthesize a polyester having a carboxyl group at a terminal, and 754 parts of toluene was further added. The obtained resin solution (hereinafter referred to as “resin liquid (3-A)
") Was 50.0% of non-volatile content, and Y was Gardner viscosity (25 ° C). The peak molecular weight of this resin determined by GPC was about 700. Production Example 4 of Resin (b) Having Onium Salt-Containing Group Production Example 4 A mixture of four 627 parts of Epicoat # 154 (manufactured by Ciel Chemical), 1306 parts of ethylene glycol monobutyl ether, 252 parts of acrylic acid and 427 parts of thiodiglycol It was charged in a neck flask and reacted at 80 ° C. for 3 hours. The obtained resin liquid (hereinafter, this resin liquid is referred to as “resin liquid (1-B)”) had a nonvolatile content of 47.8% and a Gardner viscosity (25 ° C.) of P. The peak molecular weight of this resin determined by GPC was about 1,000. Production Example 5 A mixture of 900 parts of Epicoat # 1001 (manufactured by Ciel Chemical), 204 parts of pivalic acid, 180 parts of pyridine and 1284 parts of n-butanol was charged into a four-necked flask and reacted at 50 ° C. for 10 hours. The obtained resin liquid (hereinafter, this resin liquid is referred to as “resin liquid (2-B)”) has a nonvolatile content of 48.2% and a Gardner viscosity (25%).
° C) was H. The peak molecular weight of this resin determined by GPC was about 1200. Production Example 6 A mixture of 93 parts of epichlorohydrin, 89 parts of dimethylaminoethanol and 50 parts of 88% formic acid was charged in a four-necked flask and reacted at 70 ° C. for 40 minutes. The obtained resin liquid (hereinafter referred to as “resin liquid (3-B)”) has a nonvolatile content of 9%.
The Gardner viscosity (25 ° C.) was T. The peak molecular weight of this resin by GPC was about 200. Example 1 98 parts of the resin liquid (1-A) obtained in Production Example 1 and the resin liquid (1-B) obtained in Production Example 4
2) The mixture with 2 parts was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and was heated at 120 ° C. for 30 minutes to be cured. Example 2 50 parts of the resin liquid (1-A) obtained in Production Example 1 and the resin liquid (1-B) obtained in Production Example 4
And 50 parts of the mixture were applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and heated at 120 ° C. for 30 minutes to be cured. Example 3 30 parts of the resin liquid (1-A) obtained in Production Example 1 and the resin liquid (1-B) obtained in Production Example 4
) And a mixture with 70 parts was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 µm, and was heated at 120 ° C for 30 minutes to be cured. Example 4 98 parts of the resin liquid (2-A) obtained in Production Example 2 and the resin liquid (2-B) obtained in Production Example 5
2) The mixture of 2 parts was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and heated at 100 ° C. for 10 minutes to be cured. Example 5 95 parts of the resin liquid (2-A) obtained in Production Example 2 and the resin liquid (2-B) obtained in Production Example 5
5) A mixture of 5 parts was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and heated at 100 ° C. for 10 minutes to be cured. Example 6 70 parts of the resin liquid (2-A) obtained in Production Example 2 and the resin liquid (2-B) obtained in Production Example 5
And 30 parts of the mixture were applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and heated at 100 ° C. for 10 minutes to be cured. Example 7 99.5 parts of the resin liquid (3-A) obtained in Production Example 3 and the resin liquid (3
-B) A mixture with 0.5 part was wet-coated on a mild steel plate and a glass plate with a wet film thickness of 100 μm.
And heated at 160 ° C. for 2 hours to cure. Example 8 95 parts of the resin liquid (3-A) obtained in Production Example 3 and the resin liquid (3-B) obtained in Production Example 6
5) The mixture with 5 parts was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 µm, and was heated at 160 ° C for 2 hours to be cured. Example 9 90 parts of the resin liquid (3-A) obtained in Production Example 3 and the resin liquid (3-B) obtained in Production Example 6
) The mixture with 10 parts was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 µm, heated at 160 ° C for 2 hours, and cured. Comparative Example 1 100 parts of the resin liquid (1-A) obtained in Production Example 1 was applied to a mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and heated at 150 ° C. for 30 minutes to be cured. Comparative Example 2 98 parts of the resin liquid (1-A) obtained in Production Example 1 and benzoyl peroxide 2
The mixture was applied to a mild steel mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and was heated at 150 ° C. for 30 minutes to be cured. Comparative Example 3 A mixture of 98 parts of the resin solution (2-A) obtained in Production Example 2 and 2 parts of sodium ethylate was applied to a mild steel plate and a glass plate so as to have a wet film thickness of 100 μm. Heated for minutes and cured. Comparative Example 4 A mixture of 95 parts of the resin liquid (3-A) obtained in Production Example 3 and 5 parts of tetramethylammonium chloride was applied to a mild steel plate and a glass plate so as to have a wet film thickness of 100 μm. The following tests were performed on the coated plates obtained in Examples 1 to 9 and Comparative Examples 1 to 4 which were heated and cured for 2 hours. That is, an acetone extraction test was performed using a material coated on a glass plate, and a water resistance test was performed using a material coated on a mild steel plate. In addition, a storage stability test was performed on each of the resin solutions obtained in Examples 1 to 9 and Comparative Examples 1 to 4. The results are shown in Table 1 below.

Claims (1)

Claims (a) From the group consisting of acrylic resins, polyester resins and epoxy resins
A selected resin having a polymerizable unsaturated group in the molecule, and (b) a compound represented by the following formula (I) in the molecule: [In the formula, R ₁ represents a hydroxyl group, an alkoxy group, an ester group, a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a hydrogen atom. And Y represents a sulfur atom. R ₂ , R ₃ and R ₄ are the same or different and each have 1 carbon atom;
To 14 organic groups. Further, R ₂ and R ₃ or R ₂ , R ₃ and R ₄ may be taken together to form a heterocyclic group together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. ] A curable resin composition comprising a resin having an aprotic onium salt-containing group represented by the formula: (A) A group consisting of acrylic resin, polyester resin and epoxy resin
(B) a resin having a polymerizable unsaturated group in a molecule selected from the group consisting of the following formula (I): [In the formula, R ₁ represents a hydroxyl group, an alkoxy group, an ester group, a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a halogen atom, or a hydrogen atom. And Y represents a sulfur atom. R ₂ , R ₃ and R ₄ are the same or different and each have 1 carbon atom;
To 14 organic groups. Further, R ₂ and R ₃ or R ₂ , R ₃ and R ₄ may be taken together to form a heterocyclic group together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. ] A method for curing a resin composition, comprising: curing a curable resin composition containing a resin having an aprotic type onium salt-containing group represented by: