JPH01152110A - Curable resin and curing method thereof - Google Patents

Abstract

PURPOSE:To obtain the subject resin having excellent storage stability and curing characteristics and providing a cured product having excellent water resistance, by introducing a polymerizable unsatd. group and a specified aprotic onium salt-contg. group into a resin. CONSTITUTION:0.01-5mol. aprotic onium salt-contg. group (C) of formula I (wherein R1 is OH, alkoxy, ester, a 1-8C hydrocarbon group which may be substd. with halogen or H; formula II is formula III-IV; Z is N or P; Y is S; R2-4 are each a 1-14C org. group and R2 and R3 or R2-3 and R4 may each form a heterocyclic group together with Z and Y) based on 1kg of resin solid is introduced into a resin (A) having a peak MW (measured by gel permeation chromatography) of 250-0.1 million by reacting a resin having a 1,2-epoxy group obtd. by introducing 0.1-10mol. of polymerizable unsatd. groups (B) based on 1kg of resin solid by applying addition reaction of carboxyl group and epoxy group with tert. amine, phosphine, thio-ether and an org. acid at the same time, to obtain a resin having component B and C in one molecule.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a curable resin and a method for curing the same.

Conventional techniques and their problems Conventionally, when curing resins with unsaturated groups by heating, it is common to add radical polymerization catalysts and thiols to cause a radical addition polymerization reaction and crosslink the resin. is being carried out.

However, this method has the disadvantage that the storage stability of the curable resin composition is poor and that curing of the resin surface is hindered by oxygen in the air. As an alternative to the above method, a method has been developed 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 resin. The storage stability of the cured product is poor, and the basic catalyst remains in the cured product, reducing the water resistance of the cured product.

Means for Solving the Problems The object of the present invention is to produce a curable resin that does not have the above drawbacks, that is, has excellent storage stability and good curability, and also provides the cured product with excellent water resistance. The present invention provides a curable resin that can be cured and a method for curing the resin.

According to the present invention, one molecule contains a polymerizable unsaturated group and one eCOR of the following formula (I) -CH-CH2-W.

H [In the formula, R1 represents a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a hydroxyl group, an alkoxy group, an ester group, or a halogen atom.

Here, Z represents a nitrogen atom or a phosphorus atom, and Y represents a sulfur atom. R2, R3 and R4 are the same or different and have 1 carbon number
~14 organic groups are shown. Also, these R2 and R3 or R
2, R3 and R4 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 having an aprotic onium salt-containing group represented by the following is provided, and a method for curing the curable resin, which is characterized by curing the curable resin by heating it to 80° C. or higher.

The curable resin of the present invention is a resin having a polymerizable unsaturated group and the above-mentioned specific aprotic onium salt-containing group in one molecule. Here, as long as the resin contains a polymerizable unsaturated group and the above-mentioned onium salt-containing group, conventionally known resins such as acrylic, polyester, urethane, polybutadiene, alkyd, epoxy, and phenol can be used. It may be any resin and is not particularly limited.

In the present invention, resins having -grade hydroxyl groups are preferred from the viewpoint of curability. Further, the molecular weight of the resin is not particularly limited, but the peak molecular weight measured by gel permeation chromatography (GPC) is 250 to 10.
A value of about 0,000 is preferable, and a value of about 500 to 20,000 is more preferable. If the molecular weight of the resin exceeds the above range, the coating workability tends to decrease, which is not preferable.

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

The aprotic onium salt-containing group is represented by the above formula (I), and is a group in which the carbon atom located at the β-position from the nitrogen atom, phosphorus atom, or sulfur atom of the onium salt has a secondary hydroxyl group. It is necessary. Such aprotic onium salts include quaternary ammonium salts, quaternary ammonium salts, and quaternary ammonium salts.
It is either a grade phosphonium salt or a tertiary sulfonium salt.

Specific examples of cations in the aprotic onium salt-containing group are shown below.

(2) [In each of the above formulas, R2, R3 and R4 are the same or different and represent an organic group having 1 to 14 carbon atoms. Moreover, these R2 and R3 or R2, R3 and R4 together,
These may form a heterocyclic group together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. ] The organic groups having 1 to 14 carbon atoms represented by R2, R3 and R4 are not particularly limited as long as they do not substantially hinder the ionization of ammonium bases, phosphonium bases or sulfonium bases, such as hydroxyl groups, A hydrocarbon group having 1 to 14 carbon atoms which may contain a heteroatom such as an oxygen atom in the form of an alkoxy group or the like is generally used.

Examples of such hydrocarbon groups include aliphatic, alicyclic, or aromatic hydrocarbon groups such as alkyl groups, cycloalkyl groups, cycloalkylalkyl groups, aryl groups, and aralkyl groups. The above-mentioned alkyl group may be linear or branched, and preferably has 8 or less carbon atoms, preferably a lower one, such as methyl, ethyl, n- or 1so-propyl, n- Examples include 1iso-1sec- or tert-butyl, pentyl, heptyl, and octyl groups. The above-mentioned cycloalkyl group or cycloalkylalkyl group preferably has 5 to 8 carbon atoms, and examples thereof include cyclopentyl, cyclohexyl, cyclohexylmethyl, and cyclohexylethyl groups. The above aryl groups include phenyl, tolyl, xylyl groups, and the like. Furthermore, a benzyl group is suitable as the aralkyl group.

Preferred examples of hydrocarbon groups containing a different atom, such as an oxygen atom, include a hydroxyalkyl group (especially a hydroxy lower alkyl group), specifically hydroxymethyl, hydroxyethyl, hydroxybutyl, hydroxypentyl, and hydroxyheptyl. , hydroxyoctyl group, etc., alkoxyalkyl group (especially lower alkoxy lower alkyl group), specifically methoxymethyl, ethoxymethyl, ethoxyethyl, n-propoxyethyl, 1
so-propoxymethyl, n-butoxymethyl, 1so
Examples include -butoxyethyl and tert-butoxyethyl groups.

R2 and R3 or R2, R3 and R4 taken together,
When these are heterocyclic groups formed together with the nitrogen atom, phosphorus atom, or sulfur atom to which they are bonded, -We can be exemplified by the following.

In addition, the hydrocarbon group having 1 to 8 carbon atoms which may be substituted with a hydroxyl group, an alkoxy group, an ester group or a halogen atom represented by R1 in the above formula (I) is an alkyl group, an alkenyl group, a cycloalkyl group. Examples include aliphatic, alicyclic, or aromatic hydrocarbon groups such as , cycloalkylalkyl group, aryl group, and aralkyl group. Among these, alkyl groups and alkenyl groups are preferred, and these groups may be linear or branched,
Particularly desirable are lower grades, such as methyl, ethyl, n
- or 1so-propyl, n-1iso-1sec
- or tert-butyl, pentyl, heptyl, octyl, vinyl, 2-methylvinyl groups, and the like.

Preferred examples of hydroxyl-substituted hydrocarbon groups include hydroxyalkyl groups (especially hydroxy lower alkyl groups), specifically hydroxymethyl, hydroxyethyl, hydroxybutyl, hydroxypentyl, hydroxyheptyl,
Examples include hydroxyoctyl group. Preferred examples of alkoxy-substituted hydrocarbon groups include alkoxyalkyl groups (especially lower alkoxy-lower alkyl groups), specifically methoxymethyl, ethoxymethyl, ethoxyethyl,
n-propoxyethyl, 1sO-propoxymethyl, n
-butoxymethyl, 1so-butoxyethyl, tert
-butoxyethyl group and the like. Preferred examples of the ester group-substituted hydrocarbon group include a lower alkoxycarbonylalkyl group, a lower alkoxycarbonylalkenyl group, and specifically methoxycarbonylmethyl, propoxycarbonylethyl, ethoxycarbonylpropyl, methoxycarbonylbutyl, methoxycarbonylbutylnyl, Examples include ethoxycarbonylpropyl group. Preferred examples of the halogen atom-substituted hydrocarbon group include chloromethyl, bromomethyl, iodomethyl, dichloromethyl, trichloromethyl, chloroethyl, chlorobutyl, and the like.

At least one polymerizable unsaturated group is required per molecule, and from the viewpoint of curability, the number of polymerizable unsaturated groups is 0.1 per kg of resin solid content.
It is preferably in the range of ~10 moles, and more preferably in the range of 0.5 to 5 moles. If the amount is less than 0.1 mole, the resin will not be cured sufficiently, while if it is more than 10 moles, the mechanical properties of the cured product will tend to deteriorate, so both are not preferred.

The amount of the aprotic onium salt-containing group is preferably in the range of 0.01 to 5 moles, more preferably in the range of 0.1 to 2 moles per kg of resin solid content. 0.
If the amount is less than 0.01 mole, curing tends to be insufficient, which is not preferable.

On the other hand, if the amount exceeds 5 moles, the water resistance of the cured product obtained by curing may decrease, which is not preferable.

The polymerizable unsaturated group can be introduced into the resin by employing conventionally known means. For example, (i) addition reaction between carboxyl group and epoxy group, (11) addition reaction between hydroxyl group and epoxy group, (iii) esterification reaction between hydroxyl group and carboxyl group, (1v) addition reaction between isocyanate group and hydroxyl group. , (V) half-esterification reaction between hydroxyl group and acid anhydride, (vl) transesterification reaction between hydroxyl group and ester group, etc. to add polymerizable unsaturation to one or both of the compounds or resins having these functional groups. This can be achieved by using a compound having a group.

The introduction of the onium salt into the above resin can be carried out, for example, in the following (a).
Alternatively, it can be carried out according to the method shown in (b).

(a) In a water-miscible inert organic solvent, 2-halogen-
Tertiary amine to resin having 1-hydroxyethyl group,
A method of reacting phosphine or thioether, then replacing halogen atoms with hydroxyl groups by anion exchange, and then reacting this with an organic acid.

Taking as an example a case where a tertiary amine is used as a compound to be reacted with the resin, the reaction formula is as follows.

0HR4 0HR4 [In the formula, [F] represents the base portion of the resin, and X represents a halogen atom. R2, R3 and R4 are the same as above. ] When using a phosphine instead of a tertiary amine, it is sufficient to replace N with P in the above reaction formula, and also to use a tertiary amine.
When a thioether is used instead of a class amine, N may be replaced with S and -R4 may be deleted in the above reaction formula.

The reaction between the above resin and tertiary amine etc. is approximately 100 to 15
The reaction is carried out under heating at 0° C. and takes about 1 to 20 hours to complete.

In order to substitute a halogen atom with a hydroxyl group, the resin to be treated may be passed through a conventional anion exchange resin such as a bead-type anion exchange resin.

Further, the reaction between the hydroxyl-substituted resin thus obtained and the organic acid can easily proceed by simply mixing the two at room temperature.

(b) A method in which a resin having a 1,2-epoxy group is simultaneously reacted with a tertiary amine, a phosphine or a thioether, and an organic acid in a water-miscible inert organic solvent.

Taking as an example a case where a tertiary amine is used as a compound to be reacted with the resin, the reaction formula is as follows.

■■ [In the formula, RI, R2, R3, R4 and [F] are the same as above. ] When using phosphine instead of a tertiary amine and when using a tertiary amine
When a thioether is used instead of a class amine, in the above reaction formula, N may be replaced with P, or N may be replaced with S and -R4 may be deleted, as in the case of (a) above.

The reaction of the above resin, tertiary amine, etc. and organic acid takes about 40 minutes.
The reaction is carried out under heating at ~80°C, and the reaction is completed for about 1 to 20 hours.

Examples of the water-miscible inert organic solvent used in (a) and (b) above include ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, ethanol,
Examples include alcoholic solvents such as propatool and butanol.

The organic acid is an organic carboxylic acid that generates an anion in which R1 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. A wide range of conventionally known substances can be used as long as they exist, specifically acetic acid, formic acid, trimethylacetic acid,
Examples include acrylic acid, methacrylic acid, lactic acid, hydroxyacetic acid, crotonic acid, chloroacetic acid, monomethyl maleate, monoethyl fumarate, monomethyl itaconate, and the like. Among these, those having a dissociation constant (pKa value) of 1×10 −5 or more are particularly preferred.

In addition, when the resin is an acrylic resin, the onium salt can be introduced into the resin according to the methods (a) and (b) above, but the following general formula % formula % [wherein R5 is a hydrogen atom or a methyl Indicates the group. R1 and W
is the same as above. ] It can also be carried out by polymerizing the (meth)acrylic acid ester monomer represented by the formula alone or together with a comonomer copolymerizable therewith according to a conventional method.

The resin into which the polymerizable unsaturated group and the onium salt have been introduced according to the above method can be used as an organic solvent type, or the resin liquid obtained by using a water-miscible solvent as a solvent during resin preparation. It is used in the form of an aqueous solution or dispersion by adding water to or blending in water.

The solution or dispersion of the curable resin of the present invention obtained above is mixed with various additives such as coloring pigments, extender pigments, antirust pigments, dyes, and other leveling agents, antifoaming agents, and anti-sagging agents. Good too.

When curing the curable resin of the present invention, for example, a solution or dispersion of the curable resin is applied to the object to be coated using a conventional method such as spray coating, brush coating, roll coating, or dip coating. Temperature of 80°C or higher, preferably 100°C
It may be heated at a temperature of 120 to 200° C. or higher, preferably 5 minutes or more, and more preferably 10 to 30 minutes. The curing reaction mechanism in this case is not clear, but since the disappearance of unsaturated groups is observed in changes in the infrared absorption spectrum, it is possible that the polymerization of polymerizable unsaturated groups or the transfer of active hydrogen such as hydroxyl groups to polymerizable unsaturated groups This is thought to be due to an addition reaction. Also, during the above heating,
In addition to the curing reaction, Hofmann decomposition of the onium salt in the resin occurs, and as a result, excellent water resistance can be imparted to the cured product.

Effects of the Invention In the present invention, a specific aprotic onium salt contained in the resin acts as a catalyst during crosslinking and curing of the resin, and easily causes Hofmann decomposition during or after crosslinking and curing of the resin. The onium salt is no longer contained in the cured product, and as a result, it exhibits an excellent effect of preventing a decrease in water resistance of the cured product. Therefore, the resin of the present invention has excellent storage stability and good curability. Further, according to the method of the present invention, a cured product with excellent water resistance can be obtained.

The resin of the present invention can be suitably used as a resin for low-temperature curing paints and the like.

Example Examples are given below to further clarify the present invention.

Note that "parts" and "%" mean "parts by weight" and "% by weight," respectively.

Example 1 A mixture of 209 parts of Epicote #154 (manufactured by Shell Chemical Co., Ltd.), 139 parts of ethylene glycol monobutyl ether, 84 parts of acrylic acid, 31 parts of thiodiglycol, and 0.3 parts of hydroquinone was placed in a four-bottle flask and heated to 80°C.
The mixture was allowed to react for 3 hours. The obtained resin solution has a nonvolatile content of 7
0%, and the Gardner viscosity (25°C) was Z. The peak molecular weight of this resin by GPC was about 1000.

This resin solution was applied to a polished mild steel plate and a glass plate to a wet film thickness of 100 μm, and was heated at 120° C. for 10 minutes to harden.

Example 2 A mixture of 116 parts of 2-hydroxyethyl acrylate, 284 parts of glycidyl methacrylate, 600 parts of n-butyl methacrylate, and 30 parts of azobisisobutyronitrile was placed in a fourth flask containing 667 parts of n-butyl alcohol. The solution was added at 130° C. after counting at 3 o'clock, and polymerization was carried out. Thereafter, the mixture was cooled to 110° C., and further 86 parts of methacrylic acid, 0.5 parts of hydroquinone, and 1 part of tetraethylammonium chloride were added, and the mixture was reacted until the acid value became 0. After that, it was cooled to 70°C, and then acetic acid 60
1 part and 89 parts of dimethylaminoethanol were added, and the mixture was reacted for 5 hours. The resulting resin solution had a nonvolatile content of 65% and a Gardner viscosity (at 25°C) of P. G of this resin
The peak molecular weight determined by PC was approximately 12,000.

This resin solution was coated in the same manner as in Example 1, and
It was heated for 0 minutes and cured.

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 the terminal and having a peak molecular weight of about 2000 by GPC. Thereafter, the polyester was cooled to 110°C, and then 93 parts of epichlorohydrin and 1 s of epichlorohydrin were added to the polyester.
727 parts of o-butanol was added, and the mixture was reacted until the acid value reached zero. Further 90 parts of pyridine was added to this,
The reaction was carried out at 110°C for 15 hours. 1000 parts of water was added to the obtained resin solution, and this liquid was treated with an anion exchange resin to remove chloride ions, and then 50 parts of 88% formic acid was added. The resulting aqueous resin solution had a nonvolatile content of 35% and existed in an emulsion state with a Gardner viscosity (25° C.) of B.

This emulsion liquid was coated in the same manner as in Example 1, and
It was cured by heating at ℃ for 5 minutes.

Comparative Examples 1 to 3 Example 1 except that heating after painting was performed at 60°C for 2 hours
Comparative Examples 1 to 3 were prepared in the same manner as in 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 Instead of reacting 60 parts of acetic acid and 89 parts of dimethylaminoethanol in Example 2, 3 parts of sodium ethoxide was used.
The coating and heat curing treatment were carried out in the same manner as in Example 2, except that 5 parts were mixed.

The following tests were conducted on the coated plates obtained in Examples 1 to 3 and Comparative Examples 1 to 4 above. That is, an acetone extraction test was conducted using a glass plate coated, and a water resistance test was conducted using a coated polished mild steel plate. Furthermore, a storage stability test was conducted on 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)

[Claims] (1) Polymerizable unsaturated group and the following formula (I)▲ in one molecule
There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_1 is a carbon number of 1 to 8 that may be substituted with a hydroxyl group, alkoxy group, ester group, or halogen atom.
represents a hydrocarbon group or a hydrogen atom. -W^■ indicates ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. Here, Z represents a nitrogen atom or a phosphorus atom, and Y represents a sulfur atom. R_2, R_3 and R_4 are the same or different and represent an organic group having 1 to 14 carbon atoms. Also, these R
_2 and R_3 or R_2, R_3 and R_4 may together form a heterocyclic group together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. ] A curable resin having an aprotic onium salt-containing group represented by: (2) Polymerizable unsaturated group and the following formula (I)▲ in one molecule
There are mathematical formulas, chemical formulas, tables, etc. ▼ [In the formula, R_1 is a carbon number of 1 to 8 that may be substituted with a hydroxyl group, alkoxy group, ester group, or halogen atom.
represents a hydrocarbon group or a hydrogen atom. -W^■ indicates ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼. Here, Z represents a nitrogen atom or a phosphorus atom, and Y represents a sulfur atom. R_2, R_3 and R_4 are the same or different and represent an organic group having 1 to 14 carbon atoms. Also, these R
_2 and R_3 or R_2, R_3 and R_4 may together form a heterocyclic group together with the nitrogen atom, phosphorus atom or sulfur atom to which they are bonded. ] A method for curing a curable resin, which comprises curing the curable resin having an aprotic onium salt-containing group represented by the following by heating it to 80° C. or higher.