JPH06145377A - Polyester sheet and thermoformed article obtained therefrom - Google Patents

Abstract

PURPOSE:To provide a polyester sheet which is transparent and can efficiently form, e.g. a container excellent in impact resistance, and a thermoformed article obtained therefrom. CONSTITUTION:The title sheet has a density of at most 1.34g/cm<3> and is made from composition consisting of 100 pts.wt. polyester resin having ethylene terephthalate units as the principal constituent and having an intrinsic viscosity of at least 0.6 and 5-20 pts.wt. polycarbonate resin having a weight-average molecular weight of 10,000 to 250,000.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a polyester sheet and a thermoformed article thereof. More specifically, the present invention relates to a transparent polyester sheet capable of efficiently forming a container having excellent impact resistance, and a thermoformed product thereof.

[0002]

2. Description of the Related Art Polyesters, especially polyethylene terephthalate (hereinafter referred to as PET), are widely used as fibers, films and plastics because of their excellent mechanical properties, heat resistance, chemical resistance and dimensional stability. There is. Recently, a molded product formed by thermoforming a polyester sheet can be easily molded and has good transparency, gloss, and gas permeability, and therefore, attempts have been made to use it as a container for packaging various products. ing.

However, these thermoformed products have the drawbacks of lower impact resistance and easier cracking than the conventional containers made of vinyl chloride, and improvements thereof have been desired.

JP-A-57-53553 discloses a method of obtaining a polyester sheet having a high impact strength by blending a bisoxazoline compound with polyester.
No. 2013359 discloses a method for improving impact resistance of a sheet by blending a polyester with a polyolefin graft copolymer, but the polyester sheet obtained by these methods has poor transparency and is used for packaging of products. Not preferable as a container or the like.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the drawbacks of the above polyester sheet and to provide a thermoformed article having impact resistance equivalent to that of a vinyl chloride container and transparent. is there.

[0006]

That is, the present invention is based on 100 parts by weight of a polyester resin having an ethylene terephthalate unit as a main constituent and an intrinsic viscosity of 0.6 or more, and a polycarbonate having a weight average molecular weight of 10,000 to 25,000 (hereinafter referred to as PC). A sheet of a composition comprising 5 to 20 parts by weight of a resin having a density of 1.34 g.
/ Cm ³ or less, and a thermoformed article obtained by thermoforming this sheet.

The polyester resin used in the present invention is obtained by polycondensing a dicarboxylic acid component and a glycol component by a known method. Examples of the dicarboxylic acid used as the acid component include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,
Aromatic dicarboxylic acids such as 2,7-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and diphenyl-4,4-dicarboxylic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid, and adipic acid , An aliphatic dicarboxylic acid such as sebacic acid is exemplified,
These dicarboxylic acids may be used alone or in combination of two or more.

As the glycol component, ethylene glycol, triethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, bis-β-hydroxybisphenol A and the like are used. These glycols may be used alone or in combination of two or more.

A typical example of the polyester resin used in the present invention is a PET resin obtained by polycondensing terephthalic acid and ethylene glycol by a known method.

The polyester resin used in the present invention is
The intrinsic viscosity is 0.6 or more, preferably 0.8 or more. When the intrinsic viscosity is less than 0.6, the compatibility with the PC resin is deteriorated, the transparency is significantly lowered, and the impact resistance improving effect is small.

The PC resin used in the present invention is an aromatic PC which can be prepared from a dihydric phenol and phosgene or a phosgene precursor, for example, a dihydroxydiarylalkane such as bisphenol A and phosgene or a carbonic acid diester. is there.

A typical example of the PC resin used in the present invention is poly (bisphenol A) carbonate resin. The weight average molecular weight of the PC resin used in the present invention is 10,000 to 25,000.
It is preferably ˜22000. When the weight average molecular weight is less than 10,000, no impact resistance improving effect is observed, and when the weight average molecular weight is more than 25,000,
It is not preferable because the compatibility with the polyester resin deteriorates and the transparency remarkably decreases.

The proportion of PC resin added is 5 to 20 parts by weight per 100 parts by weight of polyester resin. If it is less than 5 parts by weight, the impact resistance as a sheet or as a thermoformed product is less effective, and if it exceeds 20 parts by weight, the transparency of the sheet or thermoformed product is lowered, which is not preferable.

The polyester sheet used in the present invention is a substantially unstretched sheet obtained by the ordinary film-forming means of the above composition. The unstretched sheet of the present invention has a density of 1.34 g / cm ³ or less and is substantially amorphous. If the density of the sheet is higher than 1.34 g / cm ^3, it is not preferable because the shapeability of the molded product becomes poor when the molded product is manufactured by thermoforming, or the impact strength of the thermoformed product becomes low.

Such an amorphous polyester sheet is obtained by melt-mixing the composition of the present invention with an extruder, discharging it from a slit-shaped die, and quenching it with a cooling drum.

The thermoformed article of the present invention is obtained by thermoforming the polyester sheet of the present invention. Such a thermoformed product has excellent transparency and impact resistance. Thermoforming heats and softens the sheet and presses it against the desired mold, removes the air in the gap between the mold and the material, and makes the mold adhere to the mold by atmospheric pressure or molds the sheet by compressed air above atmospheric pressure. It is possible to apply compressed air molding that makes it intimately adhere to, and molding that uses both vacuum and compressed air.

[0017]

The polyester sheet of the present invention and the thermoformed article thereof have excellent transparency and impact resistance and can be widely used as a substitute for a vinyl chloride formed article.

[0018]

EXAMPLES The present invention will be described in detail below with reference to examples. In addition,
The measurement conditions for the main physical properties are shown in Table 1.

[Table 1]

Example 1 100 parts by weight of a PET resin having an intrinsic viscosity of 0.85 and 5 parts by weight of a PC resin having a weight average molecular weight of 22,000 were blended, vacuum dried at 140 ° C. for 8 hours, and a sheet extrusion die was attached to the tip. It was supplied to the extruder having a screw diameter of 30 mmφ. Extruder cylinder temperature 240-280 ° C
Were melt-kneaded under the conditions described above, and the extruded sheet was cooled by a cooling roll to obtain a polyester sheet having a wall thickness of about 0.3 mm. Table 2 shows the sheet density and IV measurement results.

This sheet was molded using a pressure air and vacuum forming machine manufactured by Kiefeld at a molding temperature of 100 ° C., a length of 120 mm and a width of 1.
It was molded into a thermoformed product having a size of 60 mm and a height of 37 mm. Table 2 shows the measurement results of the transparency (haze) and impact resistance of the obtained molded product.

Example 2 Example 1 was repeated except that 5 mol% 1,4-cyclohexanedimethanol copolymer PET resin having an intrinsic viscosity of 0.80 was used. The results are shown in Table 2.

Example 3 Example 1 was repeated except that 10 parts by weight of a PC resin having a weight average molecular weight of 22000 was blended. The results are shown in Table 2.
Shown in.

Comparative Example 1 Example 1 except that a PET resin having an intrinsic viscosity of 0.55 was used.
I went the same way. The results are shown in Table 2.

Comparative Example 2 The procedure of Example 1 was repeated except that a PC resin having a weight average molecular weight of 30,000 was used. The results are shown in Table 2.

Comparative Example 3 The procedure of Example 1 was repeated except that the PC resin was not added. The results are shown in Table 2.

Comparative Example 4 The procedure of Example 1 was repeated except that 30 parts by weight of a PC resin having a weight average molecular weight of 22,000 was used. The results are shown in Table 2.

[0027]

[Table 2]

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Claims (2)

[Claims] 1. 100 parts by weight of a polyester resin having an ethylene terephthalate unit as a main constituent and an intrinsic viscosity of 0.6 or more and a weight average molecular weight of 10,000 to 2500.
A sheet of a composition comprising 5 to 20 parts by weight of a polycarbonate resin of 0, wherein the density of the sheet is 1.34 g.
/ Cm ³ or less, a polyester sheet. 2. A polyester thermoformed product comprising the sheet according to claim 1.