JPS62134243A - Isotactic polystyrene molded body - Google Patents

Abstract

PURPOSE:To enhance heat resistance and mechanical strength, by using isotactic polystyrene which is subjected to stretching treatment under heating and of which the heat of fusion obtained by differential scanning thermal analysis is a specific value or more. CONSTITUTION:Isotactic polystyrene is molded in such a state that a low MW org. compound is well dispersed therein and stretched under heating. The proper amount of the low MW org. compound in the molded body at the time of stretching treatment is 1-100pts.wt. of 100pts. of isotactic polystyrene. The low MW org. compound is normally evaporated and removed at the time of stretching under heating and operation is performed to that the presence amount of the low MW org. compound comes to 5pts.wt. at the time of the finish of stretching. Proper stretching temp. is 100-250 deg.C and proper stretching magnification is 1.5-100 times. The heat of fusion of the molded body obtained by differential scanning thermal analysis is 20 Joule/g or more and, if below 20 Joule/g or less, the strength of the molded body is inferior.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molded article of isotactic polystyrene having excellent heat resistance and chemical resistance. Specifically, the present invention relates to a high crystallinity interactivory polystyrene molded product obtained by a specific method.

[Conventional technology]

Isotactic polystyrene has a high melting point, relatively good chemical resistance, heat resistance, and chemical resistance! o, stock #?
However, there is a problem that the melting point and decomposition temperature of the polymer are close to each other, making it difficult to mold, and the molded product is extremely brittle and cannot be put to practical use. Therefore, it was not used for actual purposes.

[Problem that the invention seeks to solve]

It is desired to develop a molded article that takes advantage of isotactic polystyrene's inherent property of having a high melting point and that has strength enough to withstand practical use.

The present inventors have made extensive studies on isotactic polystyrene molded bodies that solve the above problems and have excellent physical properties, and have completed the present invention.

[Means to solve the problem]

That is, the present invention relates to isotactic polystyrene obtained by stretching isotactic polystyrene containing a low molecular weight organic compound under heating, which has a heat of fusion of 20 Joules/9 or more as determined by differential scanning calorimetry. This is an isotactic polystyrene molded article characterized by the following.

The isotactic polystyrene used in the present invention is obtained by polymerizing styrene using a catalyst that provides a highly stereoregular polymer of α-olefins such as ordinary propylene and butene-1. Among them,
It is preferable that the proportion of the extraction residue after extraction with boiling methyl ethyl ketone for 6 hours is 80% by weight or more, and the temperature is 135°C.
The intrinsic viscosity measured with a tetralin solution (measured by completely dissolving polystyrene at approximately 200°C and then lowering the temperature) is 0.1.
~10 Generally, a value of about 1 to 6 is appropriate.

Various catalysts are well known for producing isotactic polystyrene.As a solid catalyst, titanium trichloride obtained by reducing titanium tetrachloride with metal aluminum, hydrogen, organic aluminum, etc. can be used as needed. Examples include those obtained by pulverizing and activated in the presence of an electron-donating compound, and those obtained by supporting titanium tetrachloride on a carrier such as magnesium chloride together with an electron-donating compound if necessary.

In the polymerization of styrene, the above-mentioned solid catalyst is used in combination with alkyl aluminum such as trialkyl aluminum and dialkyl aluminum halide. Examples include butylaluminum chloride.

There are no particular restrictions on the polymerization temperature, and it is usually room temperature to 150℃.
C., preferably 50 to 100.degree. C., and polymerization can be carried out in the presence of hydrogen as a molecular weight regulator, if necessary.

In the present invention, the isotactic polystyrene obtained by the above method is molded in a state in which a low molecular weight organic compound is well dispersed, and then stretched under heating. The low molecular weight organic compound used here may be one that has good compatibility with isotactic polystyrene, and preferably has a boiling point of 50°C or higher, particularly 100 to 250°C.
For example, hydrocarbon compounds such as toluene, xylene, ethylbenzene, cumene, methylbenzene, tetralin, and decalin, halogenated hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene, and ethers such as diphenyl ether, 7disole, and dimethoxybenzene. etc.

The dispersion method involves dissolving isotactic polystyrene in a relatively large amount of a low molecular weight organic compound, then molding it.
It is also possible to remove a large excess of the low molecular weight organic compound and subject it to the stretching process, by mixing a predetermined amount of the low molecular weight organic compound and isotactic polystyrene in a Henschel mixer, etc., and then heat forming it. It is also possible to provide

The amount of low molecular weight organic compound in the molded body during the stretching treatment is 100 parts by weight of isotactic polystyrene (1 to 100 parts by weight).
A suitable amount is 100 parts by weight, and the low molecular weight organic compound is usually removed by evaporation during heating and stretching, so that the amount of the low molecular weight organic compound present is 5 parts or less at the end of the stretching.

The stretching temperature is 100 to 250°C, preferably 120°C.
~240°C is appropriate, and the stretching ratio is 1.5~1
00 times, usually 2 to 50 times is appropriate.

What is important in the present invention is that the heat of fusion obtained by differential scanning calorimetry of the obtained molded body was measured at 35° C.
It was measured by raising the temperature to 0°C.

〔Effect of the invention〕

The isotactic polystyrene molded article of the present invention has excellent heat resistance and mechanical strength, and is extremely valuable industrially.

〔Example〕 Hereinafter, the present invention will be further explained with reference to Examples.

Example 1 (i) Production of isotactic polystyrene 77(7)
Toluene in autoclave 31. Styrene 21. Highly active titanium trichloride (manufactured by Marubeni Solve A, lot number TGY
24) 1.59 and triethylaluminum 2- were added and polymerized at 70°C for 30 minutes.

Next, a small amount of methanol was added to deactivate the catalyst, and then the reaction solution was added to a large amount of methanol at room temperature to precipitate polystyrene. The obtained isotactic polystyrene was 1809, and its intrinsic viscosity (135° C. tetralin solution) was 5.6. In addition, boiling methyl ethyl ketone extraction residue (extracted for 6 hours with a Soxhlet extractor)
was 93.0%.

x1 (ii) Preparation of film The above isotactic polystyrene 29 was dissolved in 20-g of tetralin at 190°C, and then the thickness of A liquid film with a thickness of approximately 0.3 mmO was prepared, and most of the tetralin was evaporated at 50°C under a nitrogen stream to form a film containing 20 parts by weight of tetralin (100 parts by weight of polystyrene). This film was placed in a uniaxial stretching device (manufactured by Tokosha Co., Ltd.) for 18
Stretched 5 times at 0°C under a nitrogen stream, then stretched 5 times at 210°C.
After holding for a minute, it was cooled.

The obtained film was pliable and did not deform even at 150°C. A differential scanning calorimetry analysis of this film revealed that the heat of fusion was 28.2 Joules/9. The tensile strength of the film (ASTM D 882-64T) is 1
It was 200 kg 1 cr&.

Comparative Example 1 20 parts by weight of the tetralin produced in Example 1 (based on 100 parts by weight of polystyrene) was stretched three times at 160°C, the temperature was immediately lowered to obtain a film, and then dried under reduced pressure at 80°C. The resulting film was deformed at 150° and whitened. The heat of fusion obtained by differential scanning calorimetry was 19.0 joules/
9, and the tensile strength of the film is 680 kg/cr!
and was inferior to that of Example 1.

Example 2 100 g of isotactic polystyrene obtained in Example 1 (i) and 30 g of decalin were mixed and compression molded under heat at 180° C. to obtain a film with a thickness of 0.1 mm. This film was set in the stretching device in the same manner as in Example 1, and
It was stretched 6 times at 220° C. and held for 20 minutes under a nitrogen stream. The film taken out after cooling was pliable and 15
It does not deform at 0℃ and has a tensile strength of 1400kg/c.
r! , the heat of fusion was 32.1 Joules/g.

Claims (1)

[Claims] 1. An isotactic molded article obtained by stretching isotactic polystyrene containing a low molecular weight organic compound under heating, with a heat of fusion of 20 Joules/g or more as determined by differential scanning calorimetry. An isotactic polystyrene molded body characterized by: