JP2005248003A - Manufacturing method of heat-resistant styrene resin and its composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a heat-resistant styrene resin exhibiting high heat resistance and molding processability and being excellent in practical strength, mechanical properties, transparency and external appearances of a molded article thereof without complicated polymerization processes. <P>SOLUTION: The manufacturing method of the copolymer comprises using an organic peroxide having in the molecule at least three -O-O- bonds in copolymerization by a bulk polymerization method or a solution polymerization method of (A) styrene with (B) α-methylstyrene or (A) styrene with (B) α-methylstyrene and further (C) a copolymerizable monomer therewith. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a transparent thermoplastic resin and a composition thereof, which is a styrene resin and has excellent heat resistance, molding processability, practical strength, mechanical properties, transparency and excellent appearance of a molded product. It is.

Conventionally, styrene-based resins are inexpensive and have excellent transparency, moldability, and rigidity, and thus have been widely used as molding materials for household goods, electrical products, packaging materials, and the like. As the field of application expands, methods for further improving styrenic properties and adding new functions have been developed by using blends and additives with copolymers and various polymers.
However, as a method for increasing the heat resistance, there is a heat-resistant styrene-based resin (for example, see Patent Document 1) by kneading polyphenylene ether and polystyrene. However, transparency and molded product appearance are poor due to coloring derived from polyphenylene ether.

On the other hand, a means for copolymerizing a styrene monomer and a methacrylic acid monomer is also taken (see, for example, Patent Document 2), but a kind of styrene copolymer comprising the styrene-methacrylic acid copolymer thus obtained. Although the polymer resin has improved heat resistance, it has poor practical strength.
In addition, a means for copolymerizing a styrene monomer and an α-methylstyrene monomer has been taken (see, for example, Patent Document 3), but α-methylstyrene has a low polymerization reactivity unlike styrene, and is particularly aqueous. In suspension polymerization and bulk polymerization, since the molecular weight is generally difficult to increase with a generally used polymerization initiator, there are problems such as a decrease in mechanical strength and a decrease in deflection temperature under load. When aqueous emulsion polymerization is used, a high molecular weight product is easily obtained, and a satisfactory polymerization target product is easily obtained, but the productivity in the post-treatment process such as thermal deterioration, coloring, and salting out due to the remaining surfactant remains. Many problems remain, such as decline.

JP 04-117444 A Japanese Patent Publication No. 06-092462 JP 11-124461 A

  As a result of earnestly examining the above-mentioned problems, the present inventors have used a specific polymerization initiator as an essential component, and thus have excellent heat resistance and molding processability without going through a complicated polymerization process, practical strength, mechanical properties. The inventors have found that a heat-resistant styrenic resin composition having excellent performance in transparency and appearance of a molded product is obtained, and the present invention has been completed. The characteristics of the present invention are the constitution of the monomer and the organic peroxide used as the polymerization initiator.

In the present invention, when a copolymer comprising styrene and α-methylstyrene as a main component is obtained by a bulk polymerization method or a solution polymerization method, it contains three or more —O—O— bonds in the molecule as a polymerization initiator. It is characterized by using an organic peroxide.
The copolymer obtained has (A) 40 to 99% by weight of styrene, (B) 1 to 40% by weight of α-methylstyrene, and (C) 0 to 20% of other copolymerizable monomers. % (However, the total amount of (A) to (C) is 100% by weight) and the weight average molecular weight is 150,000 or more. Furthermore, it is related with the resin composition which consists of the said copolymer.

  According to the present invention, it is possible to produce a heat-resistant styrenic resin that solves problems such as a decrease in molecular weight and a decrease in practical strength, has good moldability, high heat resistance, and excellent mechanical properties in a simple process. I can do it.

In the present invention, (A) styrene is 40 to 99% by weight, (B) α-methylstyrene is 1 to 40% by weight, (C) other copolymerizable monomers are 0 to 20% by weight (provided that (A ) To (C) are produced by a bulk polymerization method or a solution polymerization method, and an organic peroxide containing three or more —O—O— bonds as a polymerization initiator. Use things. (C) The other copolymerizable monomer is at least one monomer selected from unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, and maleimide compound. Specifically, methacrylic acid, acrylic acid, N -Phenylmaleimide, cyclohexylmaleimide, maleic anhydride and the like.
(B) When α-methylstyrene is less than 1% by weight, it is difficult to impart heat resistance, and when it exceeds 40% by weight, the polymerization reactivity becomes low and it is difficult to achieve the target weight average molecular weight. .

  Organic peroxides containing three or more —O—O— bonds in the molecule are 2,2-biz (4,4-di- (t-butylperoxy) cyclohexyl) propane, 2,2-biz. (4,4-di- (t-amylperoxy) cyclohexyl) propane, 2,2-biz (4,4-di- (cumylperoxy) cyclohexyl) propane, 2,2-biz (4,4-di- ( Organic peroxides containing 4 —O—O— bonds in the molecule such as t-butylperoxy) cyclohexyl) butane and 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone . Tris (t-butylperoxy) triazine, tris (t-amylperoxy) triazine, tris (t-butylperoxycyclohexyl) triazine, tris (dicumylperoxycyclohexyl) triazine, 1,2,4-tri (t -Butyl) trimellitate, 1,2,3-tri (t-butyl) trimellitate, 1,3,5-tri (t-butyl) trimellitate, etc. An oxide is mentioned.

  The polymerization method is a bulk polymerization method or a solution polymerization method. Either continuous or batch type may be used. As polymerization conditions, polymerization may be started at 20 to 180 ° C. according to the decomposition temperature of the organic peroxide as a polymerization initiator, and bulk polymerization or solution polymerization may be performed. A chain transfer agent, a solvent, a heat stabilizer such as a general antioxidant, mineral oil, silicon oil and the like can be added as appropriate. Examples of chain transfer agents include mercaptans such as α-methylstyrene dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, 1-phenyl-2-fluorene, dipentene and chloroform, terpenes such as terpenes, halogen compounds, and terpinolene. And the like. The amount of the chain transfer agent used is not particularly limited, but generally about 0.005 to 0.1% by weight may be added to the monomer.

Solvents used as necessary include aromatic hydrocarbons such as toluene, xylene, ethylbenzene, dialkyl ketones such as methyl ethyl ketone, and may be used alone or in combination of two or more. Good. Furthermore, other solvents such as aliphatic hydrocarbons can be mixed with aromatic hydrocarbons within a range that does not lower the solubility of the polymerization product. These solvents are preferably used in an amount not exceeding 25% by weight based on the monomers. When the solvent exceeds 25% by weight, the polymerization rate is remarkably reduced, and the impact strength of the resulting resin is greatly reduced. Moreover, since a large amount of energy is required for recovering the solvent, it is economically inferior. The solvent may be added after the polymerization proceeds and becomes relatively high in viscosity, or may be added before the polymerization, but it is better to add it in a proportion of 2 to 20% by weight before the polymerization. Quality is easy to make uniform, which is also preferable from the viewpoint of controlling the polymerization temperature.
Further, as general stabilizers, for example, hindered phenols such as octadecyl-3- (3,5-tertiarybutyl-4-hydroxyphenyl) propionate and 4,6-bis (octylthiomethyl) -o-cresol Examples thereof include phosphorus processing heat stabilizers such as antioxidants and tris (2,4-di-tertiarybutylphenyl) phosphite. Each of these stabilizers may be used alone or in combination of two or more. There is no restriction | limiting in particular about addition time, Either a superposition | polymerization process or a devolatilization process may be sufficient. Moreover, a stabilizer can also be mixed with a molded article with mechanical apparatuses, such as an extruder and a Banbury mixer.

In the present invention, the devolatilization step is not particularly limited. Polymerization proceeds in the polymerization step until the unreacted monomer is preferably 60% by weight or less, and devolatilization is performed by a known method in order to remove volatile components such as the unreacted monomer. This devolatilization process is for removing unreacted substances and / or solvents from the reaction product after the polymerization reaction. For the devolatilization treatment, for example, a flash drum, a twin-screw devolatilizer, a thin film evaporator, an extruder, etc. The normal devolatilization apparatus can be used. In addition, the temperature of devolatilization processing is about 190-280 degreeC normally, and the pressure of devolatilization processing is about 1-100 torr (torr). Preferably it is 1-50 torr, More preferably, it is 1-20 torr. As a devolatilization method, for example, it is desirable to remove by a method of removing under reduced pressure under heating or an extruder designed for the purpose of devolatilization removal.
The molecular weight of the copolymer resin composed of the monomer is preferably 150,000 to 500,000 in terms of styrene-converted weight average molecular weight measured by GPC method. If the weight average molecular weight is less than 150,000, sufficient practical strength and mechanical properties are difficult to obtain, and if it exceeds 500,000, moldability tends to decrease.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, the analysis method of the resin composition in a Example and a comparative example and a molded article, and the measuring method of each physical property are as follows.
(1) Measurement sample preparation of weight average molecular weight: Dissolving about 1000 ppm of resin composition in tetrahydrofuran Measurement equipment: Showa Denko Shodex21
(Gel permeation chromatography)
Column: sample; two KF-806L
Reference; KF-800RL 2 temperature: 40 ° C
Carrier: THF 1 ml / min
Detector: RI, UV (254 nm)
Calibration curve: Tosoh monodispersed PS data processing: Sic-480

(2) Vicat softening temperature: Measured according to ISO 306 (3) Bending strength: Measured according to ISO 178 (4) Charpy impact strength: Measured according to ISO 179 (5) Measurement of melt tension Sample After being heated to a predetermined temperature and melted, it was poured into a cylinder of a capillary rheometer (Rosand Advanced Capilary Extrusion Rheometer) and then extruded from a capillary (diameter 2 mm, length 20 mm) connected to this cylinder. Was extruded into a string while maintaining a constant speed of 20 mm / min. Next, after passing the string-like material through a tension detection pulley disposed below the nozzle, the winding speed is varied from 5 m / min to 100 m / min using a winding roll, and the maximum tension is obtained. Was used as melt tension.

[Example 1]
74 parts by weight of styrene, 25 parts by weight of α-methylstyrene, 1 part by weight of methacrylic acid and 0.005 part by weight of a polymerization initiator 2,2-di (4,4-di- (t-butylperoxy) cyclohexyl) propane Dissolved and continuously fed to a fully mixed polymerization apparatus having a capacity of 4.3 liters at a rate of 0.55 kg / hour. The reaction mixture discharged from the polymerization apparatus was supplied to a single screw extruder to remove volatile components under reduced pressure and pelletize. The polymerization reaction conditions in the polymerization process are a polymerization temperature of 120 ° C. The polymerization rate at the outlet of the reactor is 45%. The single screw extruder in the devolatilization process was set to a temperature of 230 to 240 ° C. and a vacuum degree of 14 torr.
Using the obtained pellets, a molded product was collected by a normal continuous molding method, and physical properties and the like were evaluated.

[Example 2]
Pellets and molded products were prepared in the same manner as in Example 1 except that 60 parts by weight of styrene, 30 parts by weight of α-methylstyrene, and 10 parts by weight of methacrylic acid were used in Example 1, and physical properties and the like were evaluated.
[Example 3]
Pellets and molded products were prepared in the same manner as in Example 1 except that 70 parts by weight of styrene and 30 parts by weight of α-methylstyrene were used in Example 1, and physical properties and the like were evaluated.
[Example 4]
Pellets and molded products were prepared in the same manner as in Example 1 except that 74 parts by weight of styrene, 25 parts by weight of α-methylstyrene, and 1 part by weight of maleic anhydride were used in Example 1, and physical properties and the like were evaluated.

[Example 5]
Pellets and molded products were prepared in the same manner as in Example 1 except that 74 parts by weight of styrene, 25 parts by weight of α-methylstyrene, and 1 part by weight of acrylic acid were used in Example 1, and physical properties and the like were evaluated.
[Example 6]
Pellets and molded products were prepared in the same manner as in Example 1 except that 0.005 parts by weight of 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone was used as the polymerization initiator in Example 1. Then, physical properties and the like were evaluated.

[Comparative Example 1]
Pellets and molded products were prepared in the same manner as in Example 1 except that 0.01 parts by weight of the polymerization initiator 1,1-di (t-butylperoxy) -cyclohexane was used in Example 1, and physical properties and the like were evaluated. went.
[Comparative Example 2]
Pellets and molded products were prepared in the same manner as in Example 2 except that 0.01 parts by weight of the polymerization initiator 1,1-di (t-butylperoxy) cyclohexane was used in Example 2, and physical properties were evaluated. It was.
[Comparative Example 3]
A pellet and a molded product were prepared in the same manner as in Example 3 except that 0.02 part by weight of the polymerization initiator t-butylperoxy-3,5,5-trimethylhexanoate in Example 3 was used. Evaluation was performed.

[Comparative Example 4]
A pellet and a molded product were prepared in the same manner as in Example 4 except that 0.02 part by weight of the polymerization initiator t-butylperoxy-3,5,5-trimethylhexanoate in Example 4 was used. Evaluation was performed.
[Comparative Example 5]
A pellet and a molded product were prepared in the same manner as in Example 5 except that 0.02 part by weight of the polymerization initiator t-butylperoxy-3,5,5-trimethylhexanoate in Example 5 was used. Evaluation was performed.
Monomer compositions (A to E) used in Examples 1 to 6 and Comparative Examples 1 to 5, types of polymerization initiators (a to d), physical properties of the obtained copolymers, and compositions of the copolymers Are shown in the following Tables 1 to 4, respectively.

  The heat-resistant styrenic resin of the present invention, which has excellent heat resistance, molding processability, practical strength, mechanical properties, transparency, and molded article appearance without going through a complicated polymerization process, Widely used as molding material for products, packaging materials, etc.

Claims (4)

  (A) Styrene and (B) α-methylstyrene, or (A) styrene and (B) α-methylstyrene, and (C) a copolymerizable monomer are copolymerized using a bulk polymerization method or a solution polymerization method. In the polymerization, an organic peroxide containing 3 or more —O—O— bonds in the molecule is used.   The total amount of (A) to (C) produced by the method according to claim 1 is 100% by weight, (A) styrene is 40 to 99% by weight, and (B) α-methylstyrene is 1 to 40% by weight. , (C) a copolymer comprising 0 to 20% by weight of other copolymerizable monomers.   (C) The copolymerizable monomer according to claim 1 is at least one monomer selected from unsaturated carboxylic acid, unsaturated carboxylic acid anhydride, and maleimide compound. .   A resin composition comprising the copolymer according to claim 2.