JP2720585B2 - Curable resin composition and cured product thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION INDUSTRIAL APPLICATION The present invention provides a cured film having excellent storage stability and excellent properties by curing in a short time at a relatively low temperature,
The present invention relates to a curable resin composition suitable as a heat-resistant paint, a coating agent for plants, and the like, and a cured product thereof.

Conventional technology and problems to be solved by the invention Conventionally, a silicone resin composition of a condensation-type heat-curing method is generally cured by heating to a high temperature of 250 ° C. or more for 30 minutes or more, but the temperature at the time of curing is low. If the curing time is short, the resulting cured film has the disadvantage that the solvent resistance and surface hardness are low and the composition is easily softened by heat.

Therefore, various kinds of curing catalysts and the like are added to the silicone resin composition to improve the above-mentioned drawbacks.

However, for example, zinc, tin,
Iron, cobalt, manganese, nickel, the addition of a carboxylate of a metal ion such as lead as a curing accelerator can lower the curing temperature of the silicone resin composition,
In addition to low storage stability, there is a problem that the cured film is colored by the influence of metal ions. Also, Japanese Patent Publication No. 62-55554
Japanese Patent Application Laid-Open Publication No. H11-163,087 describes a silicone resin composition containing tetramethylammonium acetate (quaternary amine) as a curing catalyst. However, this composition cannot be said to have a sufficient pot life after the addition of the curing catalyst. In some cases, the resin gradually thickened and gelled. Similarly, Japanese Patent Publication No. 58-34
No. 94 proposes a salt (tertiary amine salt) of diazabicycloundecene and acetic acid as a curing catalyst, but blending this curing catalyst improves the storage stability of the composition at low temperatures. However, the storage stability at room temperature or higher was insufficient. Further, the aluminum chelate compound proposed as a curing catalyst in JP-B-63-35183 has a problem of coloring, and JP-A-1-280546 discloses a curable composition by making a coating film extremely thin. It is described that the curability of the composition is improved, but in this case, the solvent resistance of the composition was not satisfactory.

On the other hand, the heat-resistant paint using the conventional silicone resin composition has the solvent resistance and hardness of the coating by being cured by the heat because the object to be coated has heat at the time of use. In recent years, solvent resistance and hardness have been required before use because of exposure to solvent vapor in prevention and various post-processes. Development of resin compositions has also been awaited.

Therefore, development of a silicone resin composition that provides a cured film having good curability and excellent properties has been desired.

The present invention has been made in view of the above circumstances, has good storage stability, and is cured at a relatively low temperature in a short time, and has excellent adhesion, bending resistance, impact resistance, and solvent resistance, An object of the present invention is to provide a curable resin composition that provides a cured film without discoloration and a cured product thereof.

Means and Action for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, the following general formula (1) (Where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, R ²
Is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms,
a and b are positive numbers satisfying 0 <a ≦ 1.8, 0 <b <4, and 0 <a + b <4. ) Or the silicone resin of the above formula (1) is bonded to a silicon atom of the silicone resin.
And a modified silicone resin modified with an organic resin having a functional group capable of undergoing a condensation reaction with an OR ² group, and a compound represented by the following general formula (2): R ³ ₄ P ⁺ (OR ⁴ ) ⁻ (2) ³ is a substituted or unsubstituted monovalent hydrocarbon group, R ⁴
Represents a hydrogen atom or an acyl group having 1 to 20 carbon atoms. The curable resin composition blended with the phosphonium compound represented by the formula (1) has excellent storage stability, cures at a relatively low temperature in a short time, and has good adhesion, bending resistance, impact resistance, and solvent resistance. It was found that a cured film having excellent properties and no discoloration was provided.

In this case, the curable silicone resin composition, particularly a relatively soft and highly flexible silicone resin composition has poor curability and a low crosslink density, and thus has conventionally been used at 200 ° C. for 2 hours to 2 hours.
It was necessary to cure over a long period of time at a high temperature of 1 hour at 50 ° C. Furthermore, iron octylate or cobalt octylate is used as a curing catalyst in such a silicone resin composition in an amount of 0.1%.
When added in an amount of 2 to 1.0% by weight, curing at a temperature of less than 200 ° C. is possible, but storage stability is poor and gelation may occur when stored at room temperature for one month. However, this composition is unsuitable especially as a resin for a heat-resistant paint of a bright color system. On the other hand, the silicone resin composition of the present invention using the silicone resin of the above formula (1) or its modified silicone resin and blending the phosphonium compound of the above formula (2) can be stored for a long time after the addition of the curing catalyst. Even with little increase in viscosity, excellent storage stability and high curability, e.g.
Even if it is heated at a relatively low temperature of about 0 minutes for a short time, it cures sufficiently, and even when the flexibility is high, the solvent resistance and thermal softening property of the cured film are improved, adhesion, solvent resistance, bending resistance Gives a cured film with excellent resistance and impact resistance. Furthermore, (2)
Since the phosphonium compound of the formula is colorless, it does not color the coating, and after contributing to the condensation of silanol, it thermally decomposes and scatters outside the coating, so cracking of siloxane during heating such as other metal catalysts also occurs. Therefore, the cured film provided by the composition of the present invention has no discoloration and good heat resistance.

Accordingly, the present invention provides a method for modifying a silicone resin of the above formula (1) or an organic resin having a functional group capable of subjecting the above formula (1) to a condensation reaction with an OR ² group bonded to a silicon atom of the silicone resin. A curable resin composition comprising the modified silicone resin thus obtained and the phosphonium compound of the above formula (2), and a cured product thereof.

 Hereinafter, the present invention will be described in more detail.

The curable resin composition of the present invention has the following general formula (1) as a silicone resin. Use the one indicated by.

Here, the substituent R ¹ in the formula (1) is a substituted or unsubstituted monovalent hydrocarbon group, preferably one having 1 to 10 carbon atoms, such as a methyl group, an ethyl group, a propyl group or a butyl group. Alkyl groups such as phenyl group and tolyl group, alkenyl groups such as vinyl group and allyl group, and substituted alkyl groups such as trifluoropropyl group, chloromethyl group, chloropropyl group and glycidoxypropyl group. Among them, a methyl group and a phenyl group are industrially preferable. R ² is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms, such as a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group or an isobutyl group, a vinyl group, an allyl group. And alkenyl groups such as isopropenyl group. Further, a and b are 0 <a ≦ 1.8, 0
<B <4 and 0 <a + b <4.
It is preferred that 1.2 ≦ a ≦ 1.8 and 0 <b <1 because a soft and high polymerization degree silicone resin composition can be obtained.

Although the molecular weight of the silicone resin of the formula (1) is not particularly limited, it is preferable that the average molecular weight is 10 ³ to 10 ⁶ .

Specific examples of the silicone resin of the formula (1) include KR-282,272,271,251,255,253,311, ES-1001N, KR
-9706,5221 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

Further, in the present invention, the above-mentioned (1) is used as the silicone resin.
A modified silicone resin obtained by modifying the silicone resin of the formula with an organic resin can be used.

In this case, as the organic resin, a resin having a functional group capable of undergoing a condensation reaction with the OR ² group bonded to the silicon atom in the above formula (1) is used. For example, a polyester resin containing a hydroxyl group or a carboxyl group is used. And acrylic resin.

The rate of silicone modification by the organic resin is not particularly limited, but it is preferable that the silicone resin of the formula (1) is 30% by weight or more. Specifically, examples of the modified silicone resin include ES-1001, 1001N, 1004, KR-9706, 5221 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

Then, in the present invention the following general formula (2) R ³ ₄ P as a curing catalyst ⁺ (OR ^{4) -} ... blending phosphonium compound represented by (2).

Here, R ³ in the above formula (2) is a substituted or unsubstituted monovalent hydrocarbon group, preferably one having 1 to 10 carbon atoms,
For example, alkyl groups such as methyl group, ethyl group, propyl group and butyl group, aryl groups such as phenyl group and tolyl group, alkenyl groups such as vinyl group and allyl group, chloropropyl group, chloromethyl group and trifluoropropyl group Of these, a butyl group, a phenyl group and the like are industrially suitable. R ⁴ is a hydrogen atom or an acyl group having 1 to 20 carbon atoms, for example, a hydrogen atom, an acetyl group, a propionyl group, a benzoyl group, a C ₇ H ₁₅ CO
Group, C ₁₁ H ₂₃ CO group, C ₁₅ H ₃₁ CO group and the like.

Specific examples of the phosphonium compound of the formula (2) include tetrabutylphosphonium hydroxide, tetrabutylphosphonium acetate, tetrabutylphosphonium octoate, and tetrabutylphosphonium benzoate. Butyl phosphonium carboxylate is preferably used.

Further, in the present invention, the addition amount of the phosphonium compound of the above formula (2) is 0.001 to 5 parts with respect to 100 parts (parts by weight, hereinafter the same) of the silicone resin of the above formula (1) or modified silicone resin thereof, particularly The amount is preferably 0.02 to 2 parts. If the amount is less than 0.001 part, the curing promoting effect may not be sufficiently exhibited, and if it exceeds 5 parts, the storage stability of the composition may be deteriorated.

Although the silicone resin composition of the present invention can be used without solvent, it is preferable to use it after dissolving it in an organic solvent. Examples of the organic solvent include hexane, octane, and the like.
Aliphatic hydrocarbons such as ligroin and mineral spirits, aromatic hydrocarbons such as benzene, toluene, and xylene; alcohols such as methanol, ethanol, isopropyl alcohol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; chloroform, carbon tetrachloride;
Chlorides such as trichlorethylene and perchlorethylene,
Esters such as methyl acetate, ethyl acetate and isobutyl acetate; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone;

Optional components can be added to the silicone resin composition of the present invention as needed as long as the effects of the present invention are not impaired. Optional components include, for example, thickeners, organic pigments,
Examples include pigments such as inorganic pigments, dyes, and the like.

Effects of the Invention The curable resin composition of the present invention has good storage stability, and is cured at a relatively low temperature in a short time, and has excellent adhesion, bending resistance, impact resistance, and solvent resistance. It provides a cured film without discoloration, and is used as a vehicle or heat-resistant paint for heat-resistant paints such as automobiles, motorcycles, mufflers and engine peripherals, kitchen appliances such as microwave ovens, ovens and frying pans, heaters such as stoves and fan heaters, etc. It is useful as a coating agent for plants and the like.

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In the following examples, all parts are parts by weight.

[Examples and comparative examples]

A curing catalyst is added to 100 parts of the following silicone resin A, B or C
D, E or F was added as shown in Table 1 and mixed well to obtain a silicone resin solution.

Silicone resin A (CH ₃ ) _0.75 (C ₆ H ₅ ) _0.75 SiO _1.235 (OH) A xylene solution of a silicone resin represented by _0.03 (nonvolatile content 50
%) Silicone resin B (CH ₃ ) _0.8 (C ₆ H ₅ ) _0.7 SiO _1.25 (OH) A xylene solution of a silicone resin represented by _0.02 (nonvolatile content 50%)
%) Silicone resin C Epicoat 1001 (manufactured by Yuka Shell) 60 parts and xylene 40
Part of the mixture was modified (dehydration condensation reaction) with 30 parts of (CH ₃ ) (C ₆ H ₅ ) _0.6 SiO _1.03 (OH) _0.34 and then phthalic anhydride 10
Of xylene solution of epoxy-modified silicone resin obtained by adding 60 parts of xylene (50% non-volatile content). Curing catalyst D Tetrabutylphosphonium hydroxide (40% aqueous solution) 4.5 Parts, 92 parts of isopropyl alcohol and 3.5 parts of 2-ethylhexanoic acid were stirred at room temperature for 2 hours to prepare a curing catalyst D.

Curing Catalyst E 4.5 parts of tetrabutylphosphonium hydroxide (40% aqueous solution) and 95.5 parts of isopropyl alcohol were stirred at room temperature for 2 hours to prepare a curing catalyst E.

Curing Catalyst F 16 parts of tetramethylammonium hydroxide (10% methanol solution), 2 parts of acetic acid and 265 parts of ethanol were stirred at room temperature for 2 hours to prepare a curing catalyst F (comparative catalyst).

Next, the obtained silicone resin solution was polished to a mild steel plate (0.
3mm thick) to a dry film thickness of about 20μm.
After heating and curing at 30 ° C. for 30 minutes, the physical properties of the coating were measured by the following methods.

Table 1 also shows the change over time in the viscosity of the silicone resin solution and the measurement results of the film properties.

Physical properties of coating Pencil hardness: Performed according to a pencil scratch test according to JIS K5400, Section 6-14.

Adhesion: According to JIS K5400, Item 6-15, 11 mm length and width at 1 mm intervals
A cross cut was made for each book, and a peeling test was performed using cellotape (manufactured by Nichiban).

Flex resistance: Mandrel 2mmφ according to JIS K5400, Item 6-16
The test was performed according to the test.も の indicates that there was no abnormality, and X indicates that the appearance was abnormal.

Impact resistance: Performed according to an impact deformation test according to JIS K5400, Section 6-13. A load of 500 g was dropped from a height of 10 cm, and those having no abnormality in appearance were evaluated as ○, and those in which abnormality was observed were evaluated as ×.

Solvent resistance: The coating film was rubbed 10 times with a load of about 50 g applied to 1 cm ² of absorbent cotton impregnated with xylene.

From the results in Table 1, it can be seen that the curable resin composition of the present invention has excellent storage stability, is cured at a relatively low temperature in a short time and has high hardness, adhesion, flex resistance, impact resistance, It was confirmed that a cured film having excellent solvent resistance was provided.

Claims (2)

(57) [Claims] 1. The following general formula (1) (Where R ¹ is a substituted or unsubstituted monovalent hydrocarbon group, R ²
Is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms,
a and b are positive numbers satisfying 0 <a ≦ 1.8, 0 <b <4, and 0 <a + b <4. ) Or the silicone resin of the above formula (1) is bonded to a silicon atom of the silicone resin.
And a modified silicone resin modified with an organic resin having a functional group capable of undergoing a condensation reaction with an OR ² group, and a compound represented by the following general formula (2): R ³ ₄ P ⁺ (OR ⁴ ) ⁻ (2) ³ is a substituted or unsubstituted monovalent hydrocarbon group, R ⁴
Represents a hydrogen atom or an acyl group having 1 to 20 carbon atoms. A curable resin composition characterized by comprising a phosphonium compound represented by the following formula: 2. A cured product obtained by curing the curable resin composition according to claim 1.