JP2612457B2 - Curable resin and its curing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a solution or dispersion of a curable resin and a method for curing the same.

Conventional technology and its problems Conventionally, when heating and curing a resin having an unsaturated group,
It is common practice to add a radical polymerization catalyst or polythiol to cause a radical addition polymerization reaction to crosslink a resin. 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 solution or dispersion of a curable resin free from the above-mentioned disadvantages, that is, it has excellent storage stability, good curability, and excellent cured product. It is intended to provide a solution or dispersion of a curable resin capable of imparting water resistance and a method of curing the solution or dispersion.

 According to the present invention, the following formula (I) is contained in one molecule.(R in the formula₁Represents a hydroxyl group, an alkoxy group, an ester group or
Represents a saturated group having 1 to 8 carbon atoms which may be substituted by a halogen atom.
It represents a sum or unsaturated hydrocarbon group or a hydrogen atom. −
W IsIs shown. Here, Z is a nitrogen atom or a phosphorus atom, and Y is sulfur
Indicates an atom. R_Two, R_ThreeAnd R_FourAre the same or different, oxygen
An atom may be contained, an aliphatic having 1 to 14 carbon atoms,
Shows an alicyclic or aromatic hydrocarbon group. Also these R_Twoas well as
R_ThreeOr R_Two, R_ThreeAnd R_FourTogether, these are combined
Heterocycle with nitrogen, phosphorus or sulfur atoms
Groups may be formed. Having an aprotic onium salt-containing group represented by the formula:
Resin having polymerizable unsaturated group and organic solvent
And / or curable resin characterized by containing water
A solution or dispersion is provided. Further, according to the present invention,
Heat the solution or dispersion of the above curable resin to 80 ° C or higher.
Curing resin solution or component characterized by curing by
A method of curing a liquid dispersion is provided.

The curable resin used in the present invention is a resin having the specific aprotic onium salt-containing group in one molecule and further having a polymerizable unsaturated group. Here, as the resin, as long as it contains a polymerizable unsaturated group and the above-mentioned onium salt-containing group, a conventionally known resin such as an acrylic, polyester, urethane, polybutadiene, alkyd, epoxy, or phenol resin And may be any one of them, and is not particularly limited. 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 not particularly limited, but preferably has a peak molecular weight of about 250 to 100,000 by gel permeation chromatography (GPC), and is preferably 500 to 20,000.
Are more preferred. If the molecular weight of the resin exceeds the above range, it is not preferable that the coating workability tends to decrease.

Examples of the polymerizable unsaturated group include an acryloyl group, a methacryloyl group, an itaconate group, a maleate group, a fumarate group, a crotonate group, an acrylamide group, a methacrylamide group, a cinnamic acid group, a vinyl group, and an allyl group.

The aprotic onium salt-containing group is represented by the formula (I)
Wherein the carbon atom at the β-position from the nitrogen, phosphorus or sulfur atom of the onium salt must be a group having a secondary hydroxyl group. 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 may contain an oxygen atom, and may be an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 14 carbon atoms. Show. 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. R ₂ , which may contain an oxygen atom represented by R ₃ and R ₄ , as an aliphatic, alicyclic or aromatic hydrocarbon group having 1 to 14 carbon atoms, an ammonium base, a phosphonium base or a sulfonium It is not particularly limited as long as it does not substantially hinder the ionization of the base.For example, a hydroxyl group, an aliphatic or alicyclic group having 1 to 14 carbon atoms which may contain an oxygen atom in the form of an alkoxy group or the like. Alternatively, an aromatic hydrocarbon group is generally used.

Examples of such an aliphatic, alicyclic or aromatic hydrocarbon group include 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,
Examples include 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 an oxygen atom include a hydroxyalkyl group (particularly, a hydroxy lower alkyl group), specifically, hydroxymethyl, hydroxyethyl, hydroxybutyl, hydroxypentyl, hydroxyheptyl, hydroxyoctyl Groups,
Alkoxyalkyl groups (particularly lower alkoxy lower alkyl groups), specifically methoxymethyl, ethoxymethyl,
Examples include ethoxyethyl, n-propoxyethyl, iso-propoxymethyl, n-butoxymethyl, iso-butoxyethyl, tert-butoxyethyl and the like.

 R_TwoAnd R_ThreeOr R_Two, R_ThreeAnd R_FourTogether, these are
Together with the nitrogen, phosphorus, or sulfur atom
-W when the heterocyclic group is formed As below
The following can be exemplified.

Examples of the saturated or unsaturated hydrocarbon group having 1 to 8 carbon atoms which may be substituted by a hydroxyl group, an alkoxy group, an ester group or a halogen atom represented by R ₁ in the above formula (I) include an alkyl group, an alkenyl Group, cycloalkyl group,
Examples thereof include aliphatic, alicyclic, and aromatic hydrocarbon groups such as silloalkylalkyl groups, aryl groups, and aralkyl groups. Among these, an alkyl group and an alkenyl group are preferable, and these groups may be any of a linear group and a branched group, and particularly preferably a lower group, for example, methyl,
Ethyl, n- or iso-propyl, n-, iso-, se
Examples thereof include c- or tert-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. Preferable examples of the alkoxy group-substituted hydrocarbon group include an alkoxyalkyl group (particularly, a lower alkoxy lower alkyl group), specifically, methoxymethyl, ethoxymethyl, ethoxyethyl, n
-Propoxyethyl, iso-propoxymethyl, n-butoxymethyl, 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.

The polymerizable unsaturated group contained in the base portion of the resin,
At least one is required per molecule, and from the viewpoint of curability, it is preferably in the range of 0.1 to 10 mol, more preferably 0.5 to 5 mol, per kg of resin solids. 0.1
If the amount is less than 10 moles, the curing of the resin becomes insufficient. On the other hand, if the amount is more than 10 moles, the mechanical properties of the cured product tend to decrease.

The aprotic onium salt-containing group is preferably in the range of 0.01 to 5 mol per kg of resin solids,
More preferably, it is in the range of 2 to 2 mol. If the amount is less than 0.01 mol, the 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 introduction of the polymerizable unsaturated group into the base portion of 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,
i) an addition reaction between a hydroxyl group and an epoxy group, (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 a compound having such a functional group or a resin.

The onium salt can be introduced into the resin according to, for example, the following method (a) or (b).

(A) In a water-miscible inert organic solvent, 2-halogeno-
A tertiary amine on a resin having a 1-hydroxyethyl group,
A method in which a phosphine or a thioether is reacted, a halogen atom is replaced with a hydroxyl group by anion exchange, and then an organic acid is reacted.

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.

[In the formula, a resin base portion is shown, and X represents a halogen atom. R ₂ , R ₃ and R ₄ are the same as above. When phosphine is used instead of a tertiary amine,
In the above reaction formula, N may be replaced with P. When a thioether is used instead of the tertiary amine, N may be replaced with S and -R ₄ may be deleted in the above reaction formula.

The reaction between the above resin and a tertiary amine is carried out at about 100 to 150 ° C.
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.

[Wherein R ₁ , R ₂ , R ₃ , R ₄ and the same are as defined above. When phosphine is used instead of the tertiary amine and thioether is used instead of the tertiary amine, in the above reaction formula, N is replaced with P or N is replaced as in the case of the above (a). and replaced with S may be deleted the -R _4.

The reaction of the above resin, tertiary amine, etc. and organic acid is about 40
The reaction is carried out under heating at 8080 ° 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 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,
Examples thereof include acrylic acid, methacrylic acid, lactic acid, hydroxyacetic acid, crotonic acid, chloroacetic acid, monomethyl maleate, monoethyl fumarate, and monomethyl itaconate. 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 above methods (a) and (b). [In the formula, 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.

The resin into which the polymerizable unsaturated group and the onium salt have been introduced according to the above method is used as an organic solvent type,
Alternatively, use a water-miscible solvent as the solvent when making the resin,
The resulting resin solution is used in the form of an aqueous solution or an aqueous dispersion by adding water or blending in water.

The solution or dispersion of the curable resin of the present invention obtained above is blended with various additives such as a coloring pigment, an extender pigment, a rust preventive pigment, a dye, other leveling agents, an antifoaming agent, and an anti-sagging agent. Is also good.

When curing the solution or dispersion of the curable resin of the present invention, for example, the solution or dispersion of the curable resin, spray coating, brush coating, roll coating, dip coating and the like on the object to be coated according to a usual method. Paint and heat this to 80 ° C or higher,
Preferably at a temperature of at least 100 ° C, more preferably at a temperature of about 120 to 200 ° C, preferably at least 5 minutes, more preferably 10 to 30
Heat treatment may be performed for about a minute. 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 the crosslinking and curing 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 solution or dispersion of the resin of the present invention has excellent storage stability,
The curability is also good. Further, according to the method of the present invention, a cured product having excellent water resistance can be obtained.

The solution or dispersion of the resin of the present invention can be suitably used as a low-temperature-curable paint or the like.

Examples Hereinafter, the present invention will be described more specifically with reference to Examples. The terms “parts” and “%” simply mean “parts by weight” and “% by weight”, respectively. The number of moles in parentheses after the number of parts of each reactant indicates epicoat # 154 in Example 1, and in Example 2 and Comparative Example 4,
In Example 3, 2-hydroxyethyl acrylate is the mole number of each substance when epichlorohydrin is 1.0 mole.

Example 1 Epicoat # 154 (trade name, manufactured by Shell Chemical Company, phenol novolak type epoxy resin, epoxy equivalent of about 174,
A mixture of 209 parts (1.0 mol), 139 parts of ethylene glycol monobutyl ether, 84 parts (2.80 mol) of acrylic acid, 31 parts (0.61 mol) of thiodiglycol and 0.3 part of hydroquinone is charged in a four-necked flask. , 80
The reaction was carried out at 3 ° C. for 3 hours to obtain a resin solution by sulfonium salification. The obtained resin solution had a nonvolatile content of 70% and a Gardner viscosity (25 ° C.) of Z. The peak molecular weight of this resin by GPC was about 1,000. In the resin solution, the resin molecule having a sulfonium salt has a polymerizable unsaturated group in the base portion of the resin, and since the anion is based on acrylic acid, R ₁ is also polymerizable unsaturated. Having a group.

This resin solution was applied to a mild steel plate and a glass plate so as to have a wet film thickness of 100 μm, and was cured by heating at 120 ° C. for 10 minutes.

Example 2 116 parts (1.0 mol) of 2-hydroxyethyl acrylate, 284 parts (2.0 mol) of glycidyl methacrylate, n
A mixture of 600 parts (4.23 mol) of butyl methacrylate and 30 parts of azobisisobutyronitrile was added to a four-necked flask containing 667 parts of n-butyl alcohol at 130 ° C. for 3 hours, and polymerization was carried out. Done. Thereafter, the mixture was cooled to 110 ° C., and further 86 parts (1.0 mol) of methacrylic acid, 0.5 part of hydroquinone and 1 part of tetraethylammonium chloride were added and reacted until the acid value became 0. By this reaction, one mole of two moles of the epoxy group based on glycidyl methacrylate in the acrylic resin reacted with the carboxyl group of methacrylic acid to introduce a polymerizable unsaturated double bond. Thereafter, the mixture was cooled to 70 ° C., and 60 parts of acetic acid (1.
0 mol) and 89 parts of dimethylaminoethanol (1.0 mol) were added and reacted for 5 hours to obtain a resin solution having a resin in which 1 mol of the remaining glycidyl methacrylate-based epoxy group was ammonium chlorided. The obtained resin solution had a nonvolatile content of 65% and a Gardner viscosity (25 ° C.) of P. The peak molecular weight of this resin determined by GPC was about 12,000. In the above resin, since the anion of the ammonium salt is based on acetic acid, R ₁ does not have a polymerizable unsaturated group and has a polymerizable unsaturated double bond in an acrylic resin which is a base portion of the resin.

This resin solution was coated in the same manner as in Example 1,
Heated for minutes and cured.

Example 3 650 parts (5.0 mol) of itaconic acid and ethylene glycol
248 parts (4.0 mol) of the mixture was dehydrated and condensed at 220 ° C., and the peak molecular weight by GPC having a terminal carboxyl group was about 2
000 polyesters were synthesized. Thereafter, it is cooled to 110 ° C., and then the epichlorohydrin 93 (1.
(0 mol) and 727 parts of iso-butanol were added and reacted until the acid value became zero. In this reaction, epichlorohydrin is substituted with two carboxyl groups at the terminal of the polyester.
The reaction was carried out at a ratio of one to one, and the carboxyl group at the terminal of the remaining polyester was esterified with iso-butanol. Further 90 parts of pyridine (1.14 mol)
Was added and reacted at 110 ° C. for 15 hours. 1000 parts of water was added to the obtained resin solution, and this solution was treated with an anion exchange resin to remove chloride ions. Then, 50 parts of 88% formic acid (0.96 parts) was added.
Mol) was added. The resulting aqueous resin solution had a nonvolatile content of 35
% And was present in an emulsion state having a Gardner viscosity (25 ° C.) B. In the obtained resin solution, the resin has a polymerizable unsaturated group based on itaconic acid in the polyester resin as a base part, and the anion is based on formic acid, so that R ₁ has a polymerizable unsaturated group. I do not have.

This emulsion solution was applied in the same manner as in Example 1, and 160
Heated at ℃ for 5 minutes to cure.

Comparative Examples 1 to 3 except that heating after coating was performed at 60 ° C. for 2 hours.
Those treated in the same manner as in Comparative Examples 1 to 3 were designated as Comparative Examples 1 to 3. Example 1 corresponds to Comparative Example 1, Example 2 corresponds to Comparative Example 2, and Example 3 corresponds to Comparative Example 3.

Comparative Example 4 A resin solution was obtained in the same manner as in Example 2 except that 35 parts (0.51 mol) of sodium ethoxide were mixed instead of reacting 60 parts of acetic acid and 89 parts of dimethylaminoethanol. In the obtained resin solution, the resin has a polymerizable unsaturated group in the acrylic resin which is the base portion,
It has no onium salt and some of the remaining carboxyl groups are neutralized with sodium ions. The resin solution was coated and heat-cured in the same manner as in Example 2.

The following tests were performed on the coated plates obtained in Examples 1 to 3 and Comparative Examples 1 to 4. 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 for each of the resin solutions obtained in Examples 1 to 3 and Comparative Examples 1 to 4. The results are shown in Table 1 below.

Claims (2)

(57) [Claims] 1. A compound represented by the following formula (I)(R in the formula₁Represents a hydroxyl group, an alkoxy group, an ester group or
Represents a saturated group having 1 to 8 carbon atoms which may be substituted by a halogen atom.
It represents a sum or unsaturated hydrocarbon group or a hydrogen atom. −
W IsIs shown. Here, Z is a nitrogen atom or a phosphorus atom, and Y is sulfur
Indicates an atom. R_Two, R_ThreeAnd R_FourAre the same or different, oxygen
An atom may be contained, an aliphatic having 1 to 14 carbon atoms,
Shows an alicyclic or aromatic hydrocarbon group. Also these R_Twoas well as
R_ThreeOr R_Two, R_ThreeAnd R_FourTogether, these are combined
Heterocycle with nitrogen, phosphorus or sulfur atoms
Groups may be formed. Having an aprotic onium salt-containing group represented by the formula:
Resin having polymerizable unsaturated group and organic solvent
And / or curable resin characterized by containing water
Solution or dispersion. 2. A compound represented by the following formula (I) in one molecule:(R in the formula₁Represents a hydroxyl group, an alkoxy group, an ester group or
Represents a saturated group having 1 to 8 carbon atoms which may be substituted by a halogen atom.
It represents a sum or unsaturated hydrocarbon group or a hydrogen atom. −
W IsIs shown. Here, Z represents a nitrogen atom or a phosphorus atom, and Y represents sulfur.
Indicates an atom. R_Two, R_ThreeAnd R_FourAre the same or different, oxygen
An atom may be contained, an aliphatic having 1 to 14 carbon atoms,
Shows an alicyclic or aromatic hydrocarbon group. Also these R_Twoas well as
R_ThreeOr R_Two, R_ThreeAnd R_FourTogether, these are combined
Heterocycle with nitrogen, phosphorus or sulfur atoms
Groups may be formed. Having an aprotic onium salt-containing group represented by the formula:
Resin having polymerizable unsaturated group and organic solvent
And / or curable resin characterized by containing water
Heat the solution or dispersion to 80 ° C or higher to cure it
A method for curing a solution or dispersion of a curable resin, characterized by the following.