JPH083425A - Theremosetting composition and method for curing it - Google Patents

Abstract

PURPOSE:To obtain a composition which is excellent in storage stability, low- temperature curability, etc., and gives a cured material excellent in discoloration resistance, etc., by incorporating an organotin compound into a compound having specified reactive groups. CONSTITUTION:This composition contains a compound (A) having an epoxy group, and a silanol group and/or a hydrolyzable group directly bound to a silicon atom in the molecule and an organotin compound (B). As the compound A, a copolymer obtained by the radical copolymerization of an epoxy-containing ethylenically unsaturated monomer, an ethylenically unsaturated monomer containing a silanol group and/or a hydrolyzable group directly bound to a silicon atom and, if necessary, other ethylenically unsaturated monomer is particularly desirable. An organic solution or dispersion produced by dissolving or dispersing the composition in an organic solvent is applied to a base material and then cured by heating.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel curable composition and a curing method using the curable composition.

[0002]

Conventionally, Lewis acids (eg, aluminum chloride, tin chloride, boron fluoride, boron fluoride ether complex, etc.), metal alcoholates (eg, aluminum trialkoxide, titanium tetraalkoxide, etc.) have been used as a curing catalyst for epoxy resins. , Metal chelate compounds (trisacetylacetonatoaluminum, etc.), complexes of metal chelate compounds and active hydrogen compounds (reaction products of trisacetylacetonatoaluminum, silanol compounds, etc.)
Etc. are known.

However, among these catalysts, the curable composition containing the above-mentioned Lewis acid or metal alcoholate has remarkably poor storage stability at room temperature, and the curability composition containing the metal chelate compound or a composite thereof. Each of the compositions has drawbacks such as poor storage stability at room temperature and yellowing of the cured product.

[0004]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of developing a cured product which is excellent in storage stability and can be cured at a low temperature without discoloration.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that an epoxy group and a hydrolyzable group directly bonded to silanol and / or a silicon atom are formed. A curable composition using an organotin compound as a reactive catalyst for a compound having a is excellent in storage stability, low temperature curability, and the like, and excellent in discoloration resistance of the cured product. Heading out, the present invention has been completed.

That is, the present invention contains (A) a compound having an epoxy group and a silanol group and / or a hydrolyzable group directly bonded to a silicon atom in the same molecule, and (B) an organotin compound. After applying a thermosetting composition characterized by comprising, and an organic solution or dispersion prepared by dissolving or dispersing the thermosetting composition in an organic solvent to a substrate,
The present invention relates to a curing method characterized by heating and curing.

In the present invention, the silanol group means a hydroxyl group directly bonded to a silicon atom, and the hydrolyzable group directly bonded to a silicon atom means a group which produces a silanol group by hydrolysis.

In the present invention, examples of the hydrolyzable group directly bonded to a silicon atom include, for example, an alkoxyl group represented by the general formula —OR ⁴ , an acyloxy group represented by the general formula —OCOR ⁵ , and a general formula — A ketoxime group represented by ON = C (R ⁶ ) ₂ and the like are included. In each of the above general formulas, R ⁴ represents an alkyl group having 1 to 5 carbon atoms, preferably 1 to 3 carbon atoms, such as methyl, ethyl, propyl and butyl,
R ⁵ represents an alkyl group having 1 to 3 carbon atoms, and R ⁶ represents an alkyl group having 1 to 5 carbon atoms.

Specific examples of preferable hydrolyzable groups include alkoxyl groups such as methoxy group, ethoxy group and propoxy group; ketoxime groups such as acetoxy group such as acetoxy group and propionyloxy group, acetoxime group and propionyloxime group. Groups and the like. Among these hydrolyzable groups, an alkoxyl group having 1 to 3 carbon atoms, which has excellent effects on storage stability and low temperature curability, is particularly preferable.

In the present invention, the hydrolyzable group directly bonded to the silanol group and the silicon atom may be hereinafter collectively referred to as "reactive silicon group".

In the present invention, the epoxy group in the component (A) is an aliphatic type epoxy group in which an ether group is bonded between the carbon atoms of a linear hydrocarbon group, or between the carbon atoms of an alicyclic hydrocarbon group. The epoxy group may be any type of alicyclic epoxy group having an ether group bonded thereto, but in the case of an alicyclic epoxy group, the same silanol group (or hydrolyzable group) and ( A cationic polymerization reaction or a cationic addition reaction easily and rapidly occurs due to the organotin compound as the component B), so that it is characterized by being excellent in low-temperature curability.

The curable composition of the present invention comprises (A) a compound having an epoxy group and a reactive silicon group in the same molecule and (B) an organotin compound.

Compound (A) In the compound (A), the number of epoxy groups in the molecule is preferably about 1 or more on average, preferably about 2 to 100 on average. If the number of the epoxy groups is less than about 1 on average in one molecule, low-temperature curability is deteriorated, which is not preferable.

The number of reactive silicon groups in the compound (A) is about 1 or more on average in one molecule, preferably about 1 to about 1 on average.
A range of 300 is suitable. When the number of the reactive silicon groups is less than about 1 on average in one molecule, low temperature curability is deteriorated, which is not preferable.

The compound (A) has an average molecular weight of about 20.
0 to 100,000, preferably about 500 to 50,000
A range of 0 is preferred. If the average molecular weight is less than about 200, the durability of the cured product tends to decrease, while that of about 10
When it exceeds 10,000, the storage stability and the appearance of the cured product tend to be deteriorated, which is not preferable.

The compound (A) is a conventionally known compound as long as it satisfies the above conditions, for example, a copolymer of an ethylenically unsaturated monomer, a polyester resin, a silicone-modified polyester resin, an epoxy-modified polyester. A resin, a silicone-modified epoxy resin, a fluorine resin, or the like can be appropriately selected and used.

As the compound (A), compounds known as silane coupling agents such as γ-glycidoxypropylmethoxysilane can be used, but the storage stability, curability and durability of the cured product The properties are inferior to those of the above copolymer or resin.

Particularly preferred compounds (A) are
A copolymer of ethylenically unsaturated monomers, that is, an epoxy group-containing ethylenically unsaturated monomer, a reactive silicon group-containing ethylenically unsaturated monomer, and other ethylenically unsaturated monomers as necessary, is subjected to radical copolymerization reaction. It is a copolymer obtained by

Examples of the epoxy group-containing ethylenically unsaturated monomer include glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, allyl glycidyl ether, and 3,4-epoxycyclohexylmethyl (meth) acrylate. , At least one of these is used.

Examples of the reactive silicon group-containing ethylenically unsaturated monomer include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, and γ. -(Meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, β-
(Meth) acryloyloxyethylpropyltrimethoxysilane, these and alkoxysilane (eg, tetraalkoxysilane, trialkoxyalkylsilane, etc.)
And a reaction product of a hydroxyl group-containing ethylenically unsaturated monomer (for example, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, etc.) and a low condensate of tetraalkoxysilane. , At least one of these is used. here,
Examples of the low-condensation product of the tetraalkoxysilane include "Colcoat ES40" and "Colcoat MS40".
(All are manufactured by Colcoat Co., Ltd., trade name) and the like.

Other ethylenically unsaturated monomers to be copolymerized as required include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, octyl (meth). ) Acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate and the like C
_{1 to 24} alkyl (meth) acrylates or cycloalkyl (meth) acrylates; perfluorobutylethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate, perfluorodecylethyl Perfluoroalkyl group- or perfluoroalkenyl group-containing ethylenically unsaturated monomers such as (meth) acrylate; aromatic vinyl monomers such as styrene and vinyltoluene; nitrile monomers such as (meth) acrylonitrile; (meth) acrylamide, Examples thereof include amide monomers such as N-butoxymethyl (meth) acrylamide.

Organotin compound (B) Organotin compound (B) is a compound in which an organic group is bonded to a divalent or tetravalent tin atom and has a boiling point of 150 ° C. or higher at room temperature (20 ° C.). It is liquid or solid. The organic group is a monovalent hydrocarbon group having 1 to 20 carbon atoms, and with this hydrocarbon group, an ether bond and / or
Alternatively, it may contain an ester bond. Further, the organotin compound also includes compounds having two or more tin molecules in one molecule.

In the present invention, among the above-mentioned organotin compounds (B), organic compounds represented by the following general formulas (I) and (II) containing a hydrocarbon group as an organic group and an ether bond and / or an ester bond. A curable composition using a tin-based compound has an advantage that the storage stability, low temperature curability, yellowing resistance and other properties are further improved.

That is, as preferable organotin compounds, the general formula (R ¹ ) _n Sn (OR ² ) _4-n (I) and the general formula (R ¹ ) _p Sn (OR ² ) _2-p (II) ( In each formula, R ¹ is the same or different and has 1 to 20 carbon atoms.
Shows a monovalent hydrocarbon group. R ² is the same or different and is a monovalent hydrocarbon group having 1 to 20 carbon atoms,

[0025]

Embedded image

Is shown. R ³ represents a monovalent hydrocarbon group having 1 to 20 carbon atoms. In addition, n represents an integer of 0 to 3, and p
Represents 0 or 1, and m represents an integer of 1 to 20. ) Are included. Of these, those represented by the general formula (I) are particularly preferable.

The above-mentioned organic group and the general formula (I) or (I
The monovalent hydrocarbon group having 1 to 20 carbon atoms of the organotin compound represented by I) is an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group or a combination of these groups. It may be any type of combination. The aliphatic hydrocarbon group may be linear or branched, and may contain an unsaturated bond, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl. , Tert-butyl, n-pentyl, iso-pentyl, tert-pentyl, neo-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-
Decyl, dodecyl, tridecyl, tetradecyl groups and the like can be mentioned.

Examples of the alicyclic hydrocarbon group include a cyclohexyl group and the like. Examples of the aromatic hydrocarbon group include phenyl, methylphenyl, dimethylphenyl, toluyl and xylyl groups. In addition, examples of the group in which the aliphatic hydrocarbon group and the aromatic hydrocarbon group are combined include a benzyl group and a phenethyl group.
Among these hydrocarbon groups, an alkyl group having 1 to 20 carbon atoms and a phenyl group are preferable.

In the organotin compound represented by the above general formula (I) or (II), R ² is

[0030]

[Chemical 4]

The one having an ester bond is excellent in storage stability and low temperature curability. Further, in the general formula (I) or (II), it is preferable that R ³ is an alkyl group having 1 to 20 carbon atoms or a phenyl group.

Further, in the above general formula (I),
The one in which n is 0 or 1 is excellent in storage stability and low temperature curability.

Examples of the organotin compound represented by the general formula (I) containing an ester bond include, for example, tin tetraacetate, tin tetraoctate, tin tetralaurate, butyltin triacetate, butyltin tributyrate, and butyltin triheteroate. Xylate, butyltin trioctate, butyltin trilaurate, butyltin trimethylmalate, octyltin triacetate,
Octyltin tributyrate, octyltin trihexylate, octyltin trioctate, octyltin trilaurate, octyltin trimethylmalate, phenyltin tributyrate, phenyltin trilaurate, dibutyltin diacetate, dibutyltin dibutyrate, Dibutyltin dihexylate, dibutyltin dioctate, dibutyltin dilaurate, dibutyltin diethylmalate, dioctyltin diacetate, dioctyltin dibutyrate, dioctyltin dihexylate, dioctyltin dioctate, dioctyltin dilaurate, dioctyltin diethylmalate, Tributyltin acetate, tributyltin butyrate, tributyltin hexylate, tributyltin octate, tributyltin laureth , Tributyltin methyl maleate, tri-octyl tin acetate, tri-octyl tin butyrate, trioctyltin f carboxylate, trioctyl tin octoate, trioctyltin laurate, include trioctyltin methyl maleate and the like. In addition, examples containing an ether bond include butyltin trimethoxy, butyltin tributoxy, octyltin trimethoxy, phenyltin trimethoxy, dibutyltin dimethoxy, dioctyltin dimethoxy, dioctyltin dibutoxy, tributyltin butoxy, and the like.

Among the above, tin tetraacetate, butyltin triacetate, butyltin tributyrate, butyltin trioctate, butyltin trilaurate, octyltin triacetate, octyltin tributyrate and the like are particularly preferable.

Examples of the organotin compound represented by the general formula (II) include tin diacetate, tin dibutyrate, tin dioctate and tin dilaurate.

In the thermosetting composition of the present invention, the compounding ratio of the compound (A) and the organotin compound (B) is about 0.1 parts by weight of the organotin compound (B) per 100 parts by weight of the compound (A). 001 to 20 parts by weight, preferably about 0.01 to 15
A range of parts by weight is preferred.

When the organotin compound (B) is less than the above range, the low temperature curability is deteriorated, while when it exceeds the above range, further low temperature curability cannot be obtained, and the finished appearance and durability of the cured product are not obtained. Also decreases, which is not preferable.

The thermosetting composition of the present invention contains a colorant, a filler, an organic solvent, an ultraviolet stabilizer, an ultraviolet ray, if necessary, in addition to the above-mentioned compound (A) and organotin compound (B) components. Absorbents, flow control agents and other additives can be added.

The thermosetting composition of the present invention can be cured at a temperature of 60 ° C. or higher, and its application is not particularly limited and can be selected from a wide range of fields and applied. Particularly preferably, it can be applied to the field of paints, for example.

Next, the curing method of the present invention will be described.

The curing method of the present invention is carried out by applying an organic solution or dispersion prepared by dissolving or dispersing the above-mentioned thermosetting composition in an organic solvent onto a substrate and then heating to cure it. be able to.

The organic solvent that dissolves or disperses the thermosetting composition may be appropriately selected depending on the type of the thermosetting composition, but is usually an ester type, a ketone type, an ether type, an alcohol type, or a hydrocarbon type. A solvent such as can be used.

The base material is not particularly limited as long as it is dissolved by an organic solvent or is not melted or deteriorated by heating at about 60 ° C., and a conventionally used material is selected and used. be able to. Specific examples thereof include treated or untreated metals, plastics, papers, fibers, and coated products of these.

As a method for applying to the base material, for example, usual coating means such as spray coating, brush coating, roller coating, dip coating and the like can be used. Thereby, the coating is applied so that the dry film thickness is in the range of about 1 to 100 μm.

The heat curing is usually carried out at a temperature of about 60 ° C. or higher, preferably about 100 to 300 ° C. Also, the heating time varies greatly depending on the temperature,
For example, it is usually about 10 seconds at about 250 ° C, or about 6 seconds.
At 0 ° C., it takes about 3 hours.

[0046]

The thermosetting composition of the present invention does not react at room temperature (about 20 ° C.), but the reaction rapidly occurs when a temperature of about 60 ° C. is applied, so that the composition is stable during storage. It has excellent properties, excellent low temperature curability, and excellent discoloration resistance of the cured product. Although the reason for this is not clear, heat causes the formation of a tin-silicon complex in which the organotin compound and the silanol group (or hydrolyzable group) -containing compound are bonded, and this is then followed by cationic polymerization of the epoxy group. It is presumed that it acts as a curing catalyst that accelerates the reaction or the cationic addition reaction.

[0047]

EXAMPLES Hereinafter, production examples, examples and comparative examples will be described.
The present invention will be described more specifically.

Production Example 1 Production of Epoxy Group- and Reactive Silicon Group-Containing Compound (i) In a reaction vessel equipped with a reflux device and a stirrer, 150 g of methacryloxypropyltrimethoxysilane, 220 g of 3,4-epoxycyclohexylmethyl methacrylate, Cyclohexyl methyl acrylate 500 g, butyl methacrylate 130 g and azoisobutyronitrile 10 g
Was added dropwise to 1000 g of xylene at 110 ° C.,
By reacting for 5 hours, an acrylic resin having a number average molecular weight of 10,000 (containing about 11 epoxy groups and about 19 alkoxysilyl groups in one molecule) was produced.

Production Example 2 Production of Compound (ii) Containing Epoxy Group and Reactive Silicon Group In a reaction vessel equipped with a reflux device and a stirrer, 24 g of methacryloxypropyltrimethoxysilane, 40 g of 3,4-epoxycyclohexylmethyl methacrylate, A mixture of 500 g of cyclohexyl methyl acrylate, 436 g of butyl methacrylate and 10 g of azoisobutyronitrile was added dropwise to 1000 g of xylene at 110 ° C., and the mixture was reacted for 5 hours to obtain an acrylic resin having a number average molecular weight of 10,000 (epoxy group in one molecule. Containing about 2 and about 3 alkoxysilyl groups) were prepared.

Production Example 3 Production of Epoxy Group- and Reactive Silicon Group-Containing Compound (iii) In a reaction vessel equipped with a reflux device and a stirrer, 150 g of methacryloxypropyltrimethoxysilane, 159 g of glycidyl methacrylate, 500 g of cyclohexylmethyl acrylate, and butyl. A mixture of 191 g of methacrylate and 10 g of azoisobutyronitrile was dropped into 1000 g of xylene at 110 ° C. and reacted for 5 hours to obtain an acrylic resin having a number average molecular weight of 10,000 (about 11 epoxy groups and alkoxysilyl groups in one molecule). Containing about 19 groups).

Example 1 Compound (i) 20 containing the above epoxy group and reactive silicon group
0 g (resin solid content 100 g) was mixed with 1.5 g of butyltin triacetate to produce the curable composition of the present invention.

Examples 2 to 7 and Comparative Examples 1 and 2 The compositions of the present invention of Examples 2 to 7 and the comparative compositions of Comparative Examples 1 and 2 were prepared with the formulations shown in Table 1.

The storage stability of each curable composition of Examples and Comparative Examples was examined by the following test method.

Storage stability: The following criteria were evaluated.

⊚: No thickening at 40 ° C. for 7 days or more, ◯: 40 ° C., slightly thickening in 7 days, Δ: 40 ° C., thickening and gelling in 1 to 6 days, ×: 20 ° C. It gels in 1 hour.

Next, each curable composition of Examples and Comparative Examples was applied to a degreased mild steel plate so that the dry film thickness was about 50 μm, and then heat-cured at 140 ° C. for 30 minutes. The performance of the obtained cured product was examined by the following test method.

Appearance: The presence or absence of abnormalities such as cracks and blurring of the cured film was observed. Those with no abnormality were considered good.

Curability: The peeled cured film was extracted with an acetone solvent at a reflux temperature for 2 hours, and the residual ratio (%) of the cured film was examined.

Yellowing resistance: The film before heating and the cured film after heating were compared, and yellowing was visually observed, and evaluated according to the following criteria. ◯: Good with no change, ×: Yellowing and bad.

The test results are also shown in Table 1.

[0061]

[Table 1]

In Table 1 above, the metal chelate compound is trisacetylacetonatoaluminum.

Claims (10)

[Claims] 1. (A) Epoxy group and silanol group and /
Alternatively, a thermosetting composition comprising a compound having a hydrolyzable group directly bonded to a silicon atom in the same molecule, and (B) an organotin compound. 2. The thermosetting composition according to claim 1, wherein the epoxy group is an alicyclic epoxy group. 3. The compound (A) comprises an epoxy group-containing ethylenically unsaturated monomer, a silanol group and / or an ethylenically unsaturated monomer containing a hydrolyzable group directly bonded to a silicon atom, and optionally other. The thermosetting composition according to claim 1 or 2, which is a copolymer obtained by copolymerizing the ethylenically unsaturated monomer. 4. The thermosetting composition according to claim 1, wherein the hydrolyzable group is an alkoxyl group. 5. The organotin compound (B) has the general formula (R ¹ ) _n Sn (OR ² ) _4-n (I) (wherein R ¹ is the same or different and has 1 to 20 carbon atoms). And R ² are the same or different,
A monovalent hydrocarbon group having 1 to 20 carbon atoms, Indicates. R ³ represents a monovalent hydrocarbon group having 1 to 20 carbon atoms. Moreover, n shows the integer of 0-3 and m shows the integer of 1-20. The thermosetting composition according to claim 1, which is represented by the formula (1). 6. The organotin compound (B) has the formula (I) wherein R ² is The thermosetting composition according to claim 5, wherein 7. The organotin compound (B) according to claim 5, wherein R ³ in the general formula (I) is an alkyl group having 1 to 20 carbon atoms or a phenyl group. Thermosetting composition. 8. The thermosetting composition according to claim 5, wherein the organotin compound (B) has n of 0 or 1 in the general formula (I). 9. The organotin compound (B) according to claim 5, wherein in the general formula (I), R ¹ is an alkyl group having 1 to 20 carbon atoms or a phenyl group. Thermosetting composition. 10. An organic solution or dispersion prepared by dissolving or dispersing the thermosetting composition according to claim 1 in an organic solvent is applied to a substrate and then heated to cure. Curing method.