JPH09263616A - Production of heat-resistant resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for the production of a melt-moldable transparent heat-resistant resin having high heat-resistance. SOLUTION: A heat resistant resin is produced by synthesizing a vinyl- containing polyester by polycondensation of a polyester-forming compound containing >=80wt.% of an α-hydroxyalkyl acrylate and polymerizing the vinyl- containing polyester in the presence of a radical polymerization initiator.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a heat-resistant resin, and more particularly to a method for producing a heat-resistant resin having high heat resistance and capable of being melt-shaped.

[0002]

2. Description of the Related Art Methacrylic resins containing methyl methacrylate as a main component are transparent and have excellent weather resistance, and are also compared in terms of mechanical strength, thermal properties and molding processability. Because of its well-balanced performance, it is used in many applications such as signboards, lighting covers, nameplates, automobile parts, optical materials, decorations and sundries. However, since the glass transition temperature (Tg) of the methacrylic resin is around 110 ° C., it is difficult to use it in the field where heat resistance is required.

Therefore, as a method for improving the heat resistance of a methacrylic resin, for example, a method of imidizing a methacrylic polymer with ammonia or a primary amine (Japanese Patent Laid-Open No. Sho 5).
8-71928, JP-A-62-4704), a method of copolymerizing methyl methacrylate and cyclohexyl methacrylate (JP-A-57-18624), methyl methacrylate and adamantyl methacrylate or norbornyl methacrylate. A method of copolymerizing (JP-A-60-115605 and JP-A-60-14).
7416), a method of copolymerizing methyl methacrylate and cyclohexylmaleimide (JP-A-3-21550).
No. 8), and a method of copolymerizing methyl methacrylate, α-methylstyrene and methacrylic acid (JP-A-58).
No. 71,928, Japanese Patent Laid-Open No. 03-205407, etc.) have been proposed. Further, as a method of improving the heat resistance of the resin, a method of introducing a reactive group such as a vinyl group into a polymer chain, and reacting the reactive group between molecules to crosslink and cure is known in the field of unsaturated polyester resin. There is.

However, among the above methods, the method of imidizing a methacrylic resin and the method of copolymerizing methyl methacrylate and cyclohexylmaleimide have a drawback that the resulting resin tends to be colored yellow. Further, the method of copolymerizing methyl methacrylate with adamantyl methacrylate or norbornyl methacrylate has a problem that the thermal stability is not sufficient. Further, the method of copolymerizing methyl methacrylate and cyclohexyl methacrylate or methyl methacrylate, α-methylstyrene and methacrylic acid has a drawback that sufficient heat resistance cannot be obtained. Further, the method of introducing a vinyl reactive group improves the heat resistance represented by the thermal decomposition temperature and the heat distortion temperature, but in the curing of the unsaturated polyester, a volatile compound such as styrene is added to perform vinyl polymerization. Therefore, in addition to operational problems, this volatile component remains after the reaction, and there is a problem in safety in use.

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies in view of such circumstances, and as a result, have found a method for producing a heat-resistant resin that can solve the above problems, and completed the present invention.

That is, the present invention synthesizes a vinyl group-containing polyester by polycondensing a polyester-forming compound containing at least 80% by weight of an α-hydroxyalkyl acrylic acid ester, and then initiates radical polymerization of the vinyl group-containing polyester. A method for producing a heat-resistant resin, which comprises polymerizing in the presence of an agent.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester-forming compound used in the production of the heat-resistant resin of the present invention comprises an α-hydroxyalkyl acrylate ester in an amount of 80% by weight or more. The α-hydroxyalkyl acrylate ester is not particularly limited as long as hydroxyalkyl is introduced at the α-position of the vinyl group of acrylic acid, but preferred examples include α-hydroxymethyl methyl acrylate and α-
Examples include hydroxymethyl ethyl acrylate. The content of α-hydroxyalkyl acrylic acid ester in the polyester-forming compound needs to be 80% by weight or more, preferably 90% by weight or more, and the content of α-hydroxyalkyl acrylic acid ester is low. Then, it becomes difficult to obtain a resin having high heat resistance.

The other polyester-forming compound which can be used in combination with the α-hydroxyalkyl acrylic acid ester is not particularly limited as long as it has a structure containing a hydroxy group, a carboxyl group or a carboxylic acid ester in the molecule. Specific examples thereof include ethyl glycolate and 2-hydroxyethyl acetic acid.

The vinyl group-containing polyester can be obtained by polycondensing the above polyester-forming compound. In the polycondensation, a solvent may or may not be added. It is possible to use an organic solvent capable of dissolving the above-mentioned polyester-forming compound, such as ethyl acetate, methanol, chloroform, toluene, tetrahydrofuran, or dimethyl sulfoxide. Of these, dimethyl sulfoxide and toluene are preferably used. The amount of the solvent added is in the range of 1 to 100 parts by weight with respect to 10 parts by weight of the polyester-forming compound.

Examples of the catalyst used in the polycondensation of the polyester-forming compound include known esterification catalysts or transesterification catalysts such as concentrated sulfuric acid and P-toluenesulfonic acid. The amount of these catalysts used is in the range of 0.1 to 5 parts by weight based on 100 parts by weight of the total amount of the polyester-forming compound and the solvent.

The reaction temperature in the polycondensation is preferably room temperature or higher, more preferably 50 ° C. or higher. If the temperature is lower than room temperature, the reaction rate is low and the reaction may not proceed.

Next, the above vinyl group-containing polyester is polymerized using a known radical polymerization initiator. The vinyl group-containing polyester may be polymerized by adding a radical polymerization initiator at room temperature, kneading, and then bulk polymerization using a method such as heating. Further, the above vinyl group-containing polyester may be dissolved in a solvent for solution polymerization. Examples of the solvent that can be used include organic solvents such as ethyl acetate, chloroform, tetrahydrofuran and dimethyl sulfoxide. The amount of the solvent used is 1 to 100 with respect to 1 part by weight of the vinyl group-containing polyester.
It is preferably in the range of parts by weight.

Examples of the radical polymerization initiator used in the polymerization include 2,2'-azobis (isobutyronitrile), 1,1'-azobis (cyclohexanecarbonitrile) and 2,2'-azobis (2,2'-azobis (cyclohexanecarbonitrile). Examples thereof include azo compounds such as 4-dimethylvaleronitrile), benzoyl peroxide, lauryl peroxide, dicumyl peroxide, and di-tert-butyl peroxide. The amount of these radical polymerization initiators used is 0.01 to 10 with respect to the vinyl group-containing polyester.
% By weight.

The polymerization temperature is preferably in the range of 50 to 150 ° C.

The heat-resistant resin according to the present invention obtained as described above is thermoplastic and has high heat resistance. this is,
The chemical structure of the obtained heat-resistant resin is not clear, but α
-By polycondensing a hydroxyalkyl acrylic acid ester to synthesize a vinyl group-containing polyester and radically polymerizing the polyester, the structure of the main chain is changed, and a part of the main chain is represented by the following formula (I). It is presumed that a polymer containing such a ring structural unit is obtained.

[0016]

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[0017]

EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[Example 1] 500 m equipped with a cooling pipe
In a round-bottomed flask, 130.01 g (1.0 mol) of ethyl α-hydroxymethylacrylate and toluene 250
ml and p-toluenesulfonic acid monohydrate 1.90 g
(0.01 mol) was charged and reacted at 100 ° C. for 3 hours under a nitrogen atmosphere. Then, the reaction product was poured into n-hexane for reprecipitation, and the precipitate was dried under reduced pressure at 100 ° C. for 5 hours to obtain a polycondensate. Then, the polycondensate 10
After 4.01 g (0.80 mol) was mixed with 0.164 g of 2,2'-azobis (isobutyronitrile), the mixture was placed in a glass cell and heated at 70 ° C for 5 hours in a nitrogen atmosphere to polymerize. Then, heat treatment was further performed at 120 ° C. for 1 hour. Then, the obtained polymer was dried under reduced pressure to obtain a resin. This resin can be melt-shaped, and a colorless and transparent molded product was obtained by press molding at 300 ° C. Further, when the thermal decomposition temperature of this resin was examined by thermogravimetric analysis, the 5% weight loss temperature was 410 ° C. Also, the Vicat softening temperature of this resin was measured according to ASTM D648 and found to be 1
A value of 85 ° C was shown.

[Comparative Example 1] 2,0.01 '(1.0 mol) of ethyl α-hydroxymethyl acrylate was added to 2,2'-
Azobis (isobutyronitrile) 0. 164 g was added and put in a glass cell, heated at 70 ° C. for 5 hours in a nitrogen atmosphere for polymerization, and then post-treated at 120 ° C. for 1 hour. Then, the obtained polymer was dried under reduced pressure to obtain a resin. This resin could be melt-shaped, and a colorless and transparent molded product could be obtained by press molding at 300 ° C. However, since the polycondensation reaction was scarcely performed, the 5% weight loss temperature was as low as 250 ° C. . The Vicat softening temperature was 150 ° C.

[0020]

The heat-resistant resin obtained by the present invention is
Since it is transparent and has high heat resistance and can be melt-shaped, conventional methacrylic resins could not be used. Applications requiring particularly high heat resistance, such as automobile parts, optical materials, and optics. It can be suitably used for applications such as equipment parts, industrial parts and household parts.

Claims (1)

[Claims] 1. A vinyl group-containing polyester is synthesized by polycondensing a polyester-forming compound containing at least 80% by weight of an α-hydroxyalkyl acrylic acid ester, and then the vinyl group-containing polyester is present in the presence of a radical polymerization initiator. A method for producing a heat-resistant resin, which comprises polymerizing below.