JPH01289826A - Polyester molding - Google Patents

Abstract

PURPOSE:To obtain the title molding which is excellent in heat resistance, impact resistance and gas barrier property and can be suitably used as a container such as an ovenable tray by molding a specified liquid crystal polyester composition. CONSTITUTION:A composition comprising a liquid crystal polyester obtained by polycondensing p-hydroxybenzoic acid and/or its esterifiable derivative with 6-hydroxy-2-naphthoic acid and/or its esterifiable derivative is molded to give a molding which is excellent in heat resistance, impact resistance and gas barrier property and can be advantageously used as a container such as an ovenable tray. A laminate of a sheet of said liquid crystal polyester with a sheet of a polyethylene terephthalate sheet or a molding formed of a mixture prepared by blending the both is free from drawbacks that a container made entirely of polyethylene terephthalate has poor heat sealability and any suitable cover material cannot be found and that the impact resistance is greatly decreased when it is used under severe cooking conditions.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a polyester molded product, and more specifically, it has excellent heat deformation resistance, impact resistance, and gas barrier properties that can be cooked in an oven (sometimes called ovenable). The present invention relates to a polyester molded article that can be used for containers, etc.

[Prior Art 1 Molded bodies made of polyester, particularly polyethylene terephthalate, are widely used as various tray-shaped or cup-shaped containers. In particular, molded products that are thermoformed from polyethylene terephthalate (sometimes abbreviated as PET) sheets to which polyolefin resin has been added under conditions that allow PET to crystallize are heat-resistant as described in JP-A-59-62660. It has excellent properties and can be used as a heat-resistant container such as an ovenable tray. However, PET containers obtained by such technology have poor heat sealing properties, and it is difficult to find a suitable lid material, or the impact resistance of the container is difficult when distributing products at low temperatures or when used under harsh cooking conditions. It has the disadvantage of extremely decreasing
Improvement was desired.

[Object of the Invention] As a result of intensive research into polyester molded products free from the above-mentioned drawbacks, the present inventor discovered that specific liquid crystal polyester (hereinafter sometimes abbreviated as LCP) alone, LCP and polyethylene terephthalate (hereinafter abbreviated as PET) The inventors have discovered that the above-mentioned drawbacks can be improved by using a sheet-like laminate or a molded product made of a blended composition of LCP and PET, and have thus arrived at the present invention.

[Structure of the Invention] That is, the present invention comprises: 1. (a) p-hydroxybenzoic acid and/or its ester-forming derivative and (O) 6-hydroxy-2-naphthoic acid and/or its ester-forming derivative. A polyester thermoformed body made of liquid crystal polyester obtained by polycondensation, 2. (a) p-hydroxybenzoic acid and/or its ester-forming derivative, (b) 6-hydroxy-2-naphthoic acid and/or its A polyester thermoformed product consisting of a laminate of a liquid crystal polyester (B) layer obtained by polycondensing an ester-forming derivative and a polyester (A) layer containing ethylene terephthalate as a main repeating unit, and 3. ) Liquid crystal polyester (B) obtained by polycondensing p-hydroxybenzoic acid and/or its ester-forming derivative, (b) 6-hydroxy-2-naphthoic acid and/or its ester-forming derivative (B) 0.5 ~1
0 wt% and 99.5 to 10 wt% of polyester (A) whose main repeating unit is ethylene terephthalate.

In the present invention, liquid crystal polyester (B) means (a)
A polyester obtained by polycondensing p-hydroxybenzoic acid and/or its ester-forming derivative and (b) 6-hydroxy-2-naphthoic acid and/or its ester-forming derivative.

In the present invention, polyester (A) is not only a homopolymer of polyethylene terephthalate, but also a part of the terephthalic brewing component, for example, an aromatic compound such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarbonhenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, etc. Dicarboxylic acids; aliphatic dicarboxylic acids such as adipic acid, sepatic acid, azelaic acid, etc.:
one or more components of other difunctional carboxylic acids such as oxyacids such as p-β-hydroxyethoxybenzoic acid, p-oxybenzoic acid, ε-oxycaproic acid, etc., and/or one of the ethylene glycol components. For example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene gelylcol, diethylene glycol.

1 of other glycols such as 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, 2,2-bis(4-β-hydroxyethoxyphenyl)propane, bis(4-β-hydroxyethoxyphenyl)sulfone A copolyester substituted with more than one component is encapsulated. The total proportion of copolymer components in this copolyester is preferably 3 mol % or less based on the total acid components. Among these, a homopolymer of polyethylene terephthalate is preferred. Further, the intrinsic viscosity (sometimes abbreviated as IV) of PET is preferably 0.7 or more in order to improve impact resistance. In the thermoformed article in which LCP and PET are laminated according to the present invention, one layer each of LCP and PET may be used.
It is also possible to have three or more layers with an intermediate layer. In either case, the thickness ratio of the LCP layer is preferably 5% or more of the total thickness. If the LCP layer is too thin, the effect of improving heat resistance and impact strength will be poor.

Further, in the present invention (3), when LCP and PET are used as a blend, the mixing ratio of LCP must be 0.5 wt% or more. o.If it is less than 5 wt%, the effect of improving heat resistance etc. is poor.

Note that the PET used in the present invention is measured using a differential calorimeter (hereinafter referred to as D
The crystallization peak temperature when the temperature is lowered (sometimes abbreviated as Tcd) and the crystallization peak temperature when the temperature is raised from an amorphous state (sometimes abbreviated as Tci) are measured at (hereinafter sometimes abbreviated as ΔTc) is preferably in the range of 40 to 80°C. △
If Tc is lower than 40°C, the crystallization rate will be insufficient, the production efficiency during thermoforming of the sheet will be poor, the mold releasability will be poor, and the heat-resistant dimensional stability of the obtained thermoformed product will be poor. This is not preferable because it may be insufficient. In addition, high-speed crystallization products with a TC of more than 80° C. are not preferred because they result in poor moldability during thermoforming, and the resulting thermoformed product has low impact strength.

Adjust the crystallization rate of the polyester sheet to the above appropriate range (
In order to achieve ΔTc (40 to 80°C), it is necessary to mix a crystallization nucleating agent. For example, an inorganic compound containing magnesium silicate as a main component (sometimes called talc)
It can be obtained by blending in the range of 0.1 to 2% by weight. If the addition ratio is less than 0.1%, the effect of accelerating the crystallization rate will be insufficient, and if it is more than 2%, the strength will decrease, which is not preferable. As crystallization accelerators for PET other than magnesium silicate, sodium salts of organic carboxylic acids such as sodium montanate and sodium palmitate, oxides, sulfates, and phosphates of metals from Group ■ or Group ■ of the periodic table. , silicate.

Stearate, benzoate, salicylate, tartrate, etc. may be blended so as to have a ΔTc within the range of the present invention.

The polyester molded article of the present invention can be made of the LOP single-layer sheet, a laminated sheet of LOP and PET, or a laminated sheet of LCP and PE.
It is obtained by thermoforming a single layer sheet consisting of a mixed composition with T. Thermoforming here refers to vacuum forming, in which a sheet is softened by heating and pressed against a desired mold, the air in the gap between the mold and the material is eliminated, and the sheet is brought into close contact with the mold under atmospheric pressure, or A general term for air pressure forming, in which the sheet is brought into close contact with a mold using compressed air, and forming that uses a combination of vacuum and air pressure. As a method for molding a molded product with excellent heat resistance, for example, a sheet is thermoformed in a mold X where the Tci of PET is kept within the range of above or below Tc, and then the molded product is thermoformed in a mold Y where the temperature is kept at 1 g or less. Furthermore, there is a method of thermoforming and cooling molding. Molds X and Molds Y are of engraved shape to obtain a molded product of substantially the same shape, but Mold It is preferable that the convex shapes have different shapes, or vice versa.

[Effects of the Invention] The polyester molded article of the present invention has excellent heat resistance, impact resistance, and gas barrier properties, and can be advantageously used, for example, as a container such as an ovenable tray.

[Example] The present invention will be explained in detail with reference to Examples below.

The measurement conditions for the main physical property values are as follows.

(1) Intrinsic viscosity [IV]: Measured at 35°C in O-chlorophenol or a phenol/tetrachloroethane mixed solvent.

('2J Density [ρ]; Measured at 25°C using a density gradient pipe made of carbon tetrachloride and n-hebutane.

(3) Glass transition temperature [T! It ]; Differential calorimeter (
2 by Seiko Electronics Industries Co., Ltd. DSC-20 model)
Measured at a temperature increase rate of 0°C/win.

(4) Crystallization peak temperature during heating [Tci]: Measured under the same conditions as Tg.

(5) Melting point (polyester) [T+a]: T (measured under the same conditions as J.

(6) Crystallization peak temperature during cooling [Tcd]; Sample held at 290°C for 3 minutes using a differential calorimeter for 20'
Measured at a cooling rate of C/sin.

(Katana) Heat resistance: Fill the thermoformed body with salad oil and raise the temperature in an electronic oven (NEM-600 model manufactured by Matsushita Electric Industrial Co., Ltd.). The temperature was measured to determine the heat resistance temperature.

(8) Cold resistance: After filling the thermoformed body with water and heat-sealing the lid material, it was placed in a freezer (E C-8 newly manufactured by Hitachi).
The cold-resistant altitude was defined as the altitude at which the thermoformed body did not break when it was cooled to minus 20°C in a 00M H-1 type machine and then dropped onto a concrete floor.

(9) Tensile impact strength [Ti]: The strength of a dumbbell struck from a sample was measured at 20°C using a tensile impact test manufactured by Tester Sangyo.

(g)) Heat-sealing property: A multilayer film obtained by coextruding PET and PET copolymerized with 30 mol% isophthalic acid into a film and then biaxially stretching the film to have an area magnification of 10 times. Used as a material. The thermoformed body and the copolymerized PET layer of the film were heat-sealed at a temperature of 14
The adhesive strength when heat-sealed in the range of 0 to 240°C was 0.8Kg/15. Those above were considered good, and those lower than 0.8 and 9/15 tuta were judged poor.

Example 1 and Comparative Examples 1 and 2 Liquid crystal polyester (Vectra A- manufactured by Hoechst)
After drying PET pellets of 900) and IVl, 0 in a hot air dryer at 150°C for 5 hours, the additives shown in Table 1 for PET were added, and a sheet extrusion die was inserted at the tip. It was fed into an extruder equipped with a 50 m screw diameter. Extruder cylinder setting temperature 280-295
The extruded sheet was melt-kneaded at a temperature of 0.0°C, and the extruded sheet was cooled with a cooling roll to obtain a polyester sheet having a wall thickness of 0.5 thtn.

The obtained sheet was engraved into a mold X using an FC-IAPA-W type compressed air/vacuum forming machine manufactured by Asano Research Institute, and was molded into a vertical shape.
351n! R, width 58MIR, depth 184IIH concave tray mold as a mold vertical 133+nI1. Width 56m
+, a convex tray with a depth of 18M was used, the heating time of the sheet was set as shown in Table 1, and the contact time with mold X was 5 seconds.

Vacuum forming was performed under the conditions that the temperature of the mold Y was 20 to 50° C. and the contact time with the mold Y was 5 seconds. Table 1 shows the evaluation results of the tray thus obtained.

Examples 2 to 4 and Comparative Examples 3 to 4 A die for sheet extrusion for 2 types and 3 layers was installed at the tip, an extruder with a screw diameter of 40 Mφ was used for extruding the middle layer, and the extrusion method of Example 1 was used for extruding the outer layer. The middle layer was made of the same liquid crystal polyester as in Example 1, the outer layer was made of PET as in Comparative Example 1, and only Comparative Example 4 was made of PET as in Comparative Example 2. A multilayer sheet having the thickness structure shown in -2 was obtained.

A tray was formed from this sheet in the same manner as in Example 1, and evaluated by varying the heater output for heating the sheet and the sheet heating time. The results are shown in Table-2.

Examples 5 to 6 and Comparative Example 5 The same liquid crystal polyester as in Example 1, PET
Using the same formulation as Comparative Example 1, Table-
Same as Example 1 except that the mixture was mixed at the ratio shown in Example 3.
The sheet was extruded and a tray was formed in the same manner as in Example 2. Table 3 shows the evaluation results of the tray.

Table 1 1) Hayashi ([PKN Talc 2) Low density polyethylene (MIo, 2) Examples 7 to 8 and Comparative Examples 6 to 7 Examples 7 to 8 and Comparative Examples 6 to 7 Except for changing the wall thickness of the extruded sheet as shown in Table 2, In the same manner as in Example 1, a tray was molded and evaluated. The results are shown in Table-2.

Table 4 The molded articles of the present invention shown in Examples 1 to 8 have excellent heat resistance, cold impact resistance, and heat sealability.
It was useful as a container for food, etc.

Claims (1)

[Claims] 1. (a) Condensation polymerization of p-hydroxybenzoic acid and/or its ester-forming derivative and (b) 6-hydroxy-2-naphthoic acid and/or its ester-forming derivative A polyester molded body made of liquid crystal polyester (B) obtained by. 2. A polyester molded article comprising a laminate of a polyester (A) containing ethylene terephthalate as a main repeating unit and the liquid crystal polyester (B) according to claim 1. 3. The liquid crystal polyester (B) according to claim 1, 10 to 0.
A polyester molded article made of a mixed composition of 5% by weight of polyester (A) having ethylene terephthalate as a main repeating unit and 90 to 99.5% by weight. 4. The polyester according to any one of claims 1 to 3, which is a tray-shaped molded product obtained by thermoforming a sheet-like product, and whose wall thickness at the flat bottom position is in the range of 0.1 to 1 mm. Molded object.