JPH11286095A - Polyester multilayered film or sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film or sheet which has improved gas-barrier properties, mechanical strength, transparency, molding characteristics and can be used effectively in the industry. SOLUTION: The polyester multilayered film or sheet contains at least one layer of polyethylene terephthalate resin A and at least one layer of a copolymerized resin B of ethylene-2,6-naphthalate unit of 40-90 mole % and ethylene isophthalate unit of 60-10 mole %, wherein the ratio of the resin A to the resin B is 10-90 wt.%:10-90 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet suitable for a molded article such as a laminated multilayer film or tray made of a polyester resin having a novel property. More specifically, a laminated multilayer film or tray having excellent gas barrier properties, transparency and moldability containing at least one layer of a copolymerized polyester resin of a polyethylene terephthalate resin, ethylene-2,6-naphthalate units and ethylene isophthalate units. The present invention relates to a sheet suitable for a molded article.

[0002]

2. Description of the Related Art Conventionally, molded articles such as films and trays made of polyethylene terephthalate (hereinafter referred to as PET) have excellent properties such as mechanical strength, transparency, moldability, and chemical resistance. Widely used as. However, even in such a PET molded product, the gas barrier properties of oxygen, carbon dioxide gas, etc. are not sufficient, and when the storage is extended for a long time, when the container is small, or when a high gas barrier is required, the commercial value is reduced. It has the disadvantage of lowering.

[0003] As a method of improving such a disadvantage, PET is used.
A method of laminating a xylene group-containing polyamide resin (hereinafter referred to as MXD-6) having more excellent gas barrier properties and PET, for example, JP-A-56-64866 and JP-B-60-88.
-240409. A method of blending MXD-6 with PET is disclosed in, for example,
This is proposed in Japanese Patent Application Laid-Open No. 8-90033 and Japanese Patent Application Laid-Open No. 58-160344. Furthermore, polyethylene-2,6-naphthalate (hereinafter referred to as P
A method of laminating EN) on PET is proposed in, for example, Japanese Patent Publication No. 26940/1990.

However, such molded articles are made of PET and MXD-
In the case of laminating with MXD-6, the interlayer adhesion is very weak and peeling is apt to occur, and where MXD-6 is unstretched and laminated, whitening occurs due to moisture absorption crystallization of MXD-6. doing. Also MXD-6 in PET
When PET is blended, transparency is poor because PET and MXD-6 are incompatible, and in particular, poor transparency due to the development of pearl luster due to MXD-6 is a serious disadvantage in practical use.

On the other hand, in the case of laminating PEN and PET,
The melting temperature and glass transition temperature of N and PET are respectively
273 ° C, 113 ° C, 254 ° C, 72 ° C and PEN are P
About 20 ° C at melting temperature and about 40 at glass transition temperature from ET
° C, the difference in the basic thermal behavior of this resin appears as a problem in the molding process. For example, if the temperature of the hot runner is set to a temperature suitable for PET at the time of melt molding, white turbidity due to PEN is generated in the molded product, and in a more severe case, a solidified product is mixed. Further, if the temperature is set to a temperature suitable for PEN, the high temperature may cause thermal degradation of PET, that is, a reduction in molecular weight, and promote generation of acetaldehyde.

On the other hand, when the molded article is a stretched body, the stretching temperature at the time of stretching is Tg (72 ° C.) + 20 ° C.
g + 50 ° C., while Tg (113 ° C.) + 20 ° C. with PEN
It is generally considered that the temperature range of Tg + 50 ° C. is an appropriate temperature range. When a laminate of PET and PEN is stretched, if the stretching temperature is set to a low temperature side, PEN is in a cold stretching state and minute voids are generated. If the temperature is set to a high temperature side, the PET will be in a so-called draw stretching state without proper orientation, stretching unevenness will occur, and white turbidity will occur due to thermal crystallization.

[0007] Further, when the use ratio of PEN is increased in order to impart gas barrier properties, this drawback appears more remarkably and becomes a major drawback in molding. As described above, there is a drawback that the barrier property, moldability, and transparency are not improved in a well-balanced manner, and the improvement has been desired.

[0008]

An object of the present invention is to provide a sheet having excellent gas barrier properties and transparency and suitable for a molded article such as a laminated multilayer film or tray.

[0009]

SUMMARY OF THE INVENTION The present invention, which focuses on such problems, relates to a sheet suitable for a molded article such as a laminated multilayer film or a tray which does not have the above-mentioned drawbacks. The present inventors have found a polyester multilayer sheet or film having excellent properties and moldability and capable of improving the above-mentioned disadvantages, and have reached the present invention.

That is, according to the present invention, a polyethylene terephthalate resin (A) layer, an ethylene-2,6-naphthalate unit of 40 to 90 mol% and an ethylene isophthalate unit of 60 to 90 mol% are used.
A polyester multilayer film or sheet comprising at least one layer of 10 mol% of a copolymerized polyester resin (B), wherein the composition ratio (A) :( B) is 10 to 90.
A polyester multilayer film or sheet characterized in that it is 10% to 90% by weight based on the weight.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyethylene terephthalate resin (A) in the present invention is mainly intended for a homopolymer of polyethylene terephthalate. Aromatic dicarboxylic acids such as cyetane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, etc.
Alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid and azelaic acid, p-β
-One or more other difunctional carboxylic acids such as oxyacids such as hydroxyethoxybenzoic acid, ε-oxocaproic acid, and / or a portion of the ethylene glycol component;
For example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2-bis (4′-β −
Hydroxyethoxyphenyl) propane, bis (4'-
Copolymers substituted with one or more other polyfunctional compounds such as (β-hydroxyethoxydiphenyl) sulfonic acid and copolymerized in a range of 5 mol% or less, preferably 2 mol% or less may be used.

The polyester resin (B) in the present invention is a copolymerized polyester resin of an ethylene-2,6-naphthalate unit and an ethylene isophthalate unit, and has a 2,6-naphthalenedicarboxylic acid component of 90 to 4%.
The molar ratio is 0 mol%, preferably 80 to 50 mol%, the isophthalic acid component is 10 to 60 mol%, preferably 20 to 50 mol%, and the 2,6-naphthalenedicarboxylic acid component is 9 mol%.
When it is more than 0 mol%, copolymerization with an isophthalic acid component,
The effects of the melting temperature drop and the glass transition temperature drop due to randomization do not appear, and the effects on the melt moldability and the roll moldability during lamination molding with PET do not appear.

On the other hand, when the 2,6-naphthalenedicarboxylic acid component is less than 50 mol%, the melting temperature is remarkably lowered, the melt viscosity is lowered, and the casting from the polymerization vessel becomes very difficult. When laminating, the thermal degradation of the copolymer resin itself during melting becomes significant. And
This copolymerized polyester resin (B) is a naphthalene-
It is synthesized by combining 2,6-dicarboxylic acid and isophthalic acid with ethylene glycol under appropriate reaction conditions in the presence of a catalyst. Further, a part of the 2,6-naphthalenedicarboxylic acid component is converted to 2,7-naphthalenedicarboxylic acid. , 1,5-, 1,
6-, 1,7-other isomers of naphthalenedicarboxylic acid or terephthalic acid or one or more of the above-mentioned polyfunctional carboxylic acids and / or a part of ethylene glycol component A copolymer obtained by substituting at least one kind and copolymerizing at 5 mol% or less, preferably 2 mol% or less, may be used.

The limiting viscosities (IV) of the polyester resins (A) and (B) are within a range where melt extrusion and injection molding can be performed, a range where stretchability during heating and stretching is good,
From the mechanical properties and the like of the obtained molded product, IV: 0.3 to
1.2, preferably in the range of 0.4 to 1.0. The structure of the polyester resin (A) layer and the (B) layer in the present invention may be any combination of two or more layers of the polyethylene naphthalate resin (A) layer and the copolymerized polyester resin (B) layer. However, in particular, two layers having polyethylene terephthalate (A) as an inner layer and a copolymerized polyester resin (B) as an outer layer, and three layers having a polyethylene terephthalate layer as an innermost layer and an outermost layer and a copolymerized polyester layer as an intermediate layer are preferred. The weight ratio of each layer is from 10 to 90% by weight, especially 25 to 75% by weight, particularly from 90 to 10% by weight, particularly from 10 to 90% by weight, particularly from the effect of damp barrier properties and stretchability. 75
~ 25% by weight is preferred. If necessary, a small amount of another polymer can be added to or mixed with these resins. In this case, however, it is preferable to carry out the reaction within a range that does not substantially change the properties of the polyester resin. Examples of these additives or mixtures include polyamides, polyolefins, and other polyesters. The polyester resin may contain additives such as a matting agent, a coloring agent, and a stabilizer, if necessary.

[0015]

The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples.
First, the main methods of measuring physical properties are as follows.

Intrinsic viscosity [IV]: Measured at 35 ° C. using o-chlorophenol as a solvent.

Melting temperature [Tm]: Measured with a Takayanagi-type melting point analyzer (manufactured by Kyoto Keiki Seisakusho).

Glass transition temperature [Tg]: Differential calorimeter (P
According to ERKIN-ELMER DSC-1B), 20
Measured at a heating rate of ° C / min.

Oxygen permeability: 25 ° C. × 100 using an Ox-Tran 100 type oxygen permeability meter (manufactured by MOCON).
Measured at% RH.

Haze: Haze = (T4 / T3 × 100) -T3 (%) calculated from the following equation using a haze meter S (manufactured by Toyo Seiki Co., Ltd.) T2: Total transmitted light, T3: Depends on device Scattered light, T4:
Light intensity scattered by the instrument and sample

Degree of orientation [Δn]: A polarizing plate was set up on an Abbe refractometer, and the refractive index in the plane direction and the thickness direction of a sample cut from a stretched film was measured at a temperature of 25 ° C. using a D line of sodium. The difference between the two was calculated.

Tensile breaking strength: Tensileon (manufactured by Toyo Baldwin Co., Ltd.) was used to measure the puncture-like specimen having a width of 5 mm under conditions of a chuck distance of 40 mm and a tensile speed of 50 mm / min (23 ° C.).

The polyethylene terephthalate resin (A), the copolymerized polyester resin (B) of ethylene-2,6-naphthalate unit and ethylene isophthalate unit (B) and the polyethylene-2,6-naphthalate resin used are as follows. is there.

(1) Polyethylene terephthalate resin (A): PE manufactured by Nihon Unipet Co., Ltd. with IV = 0.75
T homopolymer.

(2) Copolymerized polyester resin of ethylene-2,6-naphthalate unit and ethylene isophthalate unit (B):
An initial condensate was produced by performing a transesterification reaction of 6-dicarboxylic acid and isophthalic acid with ethylene glycol in the presence of a catalyst, and the initial condensate was obtained by polycondensation. In this way, four types of copolymerized polyester resins [B-1] to [B-4] shown in Table 1 were obtained in an autoclave.

[0026]

[Table 1]

(3) Polyethylene-2,6-naphthalate resin In an autoclave, an ester exchange reaction between naphthalene-2,6-dicarboxylic acid and ethylene glycol is carried out in the presence of a catalyst to produce an initial condensate. IV obtained by subjecting this precondensate to polycondensation:
0.61 PEN homopolymer.

Examples 1 to 6, Comparative Example 1 Using each of the above resins, the cylinder i temperature of the multilayer sheet molding machine manufactured by Plastic Research Laboratory was set at 275 ° C.
i temperature set to 275 ° C, hot runner temperature set to 270 ° C
Setting, chill roll temperature 17 ° C setting, thickness 250μm
And a single-layer unstretched sheet is formed. Then, using this sheet, biaxial stretching is performed at a stretching temperature of 105 to 115 ° C. and a stretching ratio of 3 × 3 times using a stretching film molding machine manufactured by TM-LONG. Laminated and single-layer films were obtained. Table 2 shows the evaluation results of the oxygen gas barrier properties of the film.

[0029]

[Table 2]

As is clear from Table 2, the multilayer film obtained by laminating the PET and the copolymerized polyester resin (B) has better gas barrier properties than PET.

Examples 7 to 11 and Comparative Examples 2 to 3 Using the above resins, cylinders i and iii (PET layer cylinder) of a multilayer sheet molding machine manufactured by Plastic Research Laboratory
275 ° C setting, cylinder ii (intermediate employment cylinder) 27
5 ° C, 285 ° C, 295 ° C setting, hot runner 280
250μm thickness at ℃ setting, chill roll temperature setting at 17 ℃
And a single-layer unstretched sheet were formed. Table 3 shows the evaluation results of the transparency and the breaking strength of the sheet.

[0032]

[Table 3]

As is clear from Table 3, the multilayer sheet obtained by laminating the PET and the copolymerized polyester (B) is made of PE
Fogging unlike a multilayer sheet in which T and PEN are laminated does not appear, and the moldability with respect to transparency at the time of low-temperature melt molding is particularly excellent. Further, a sheet obtained by laminating the copolyester (B) on PET shows superior strength characteristics to a single-layer sheet of PET.

Examples 12 to 17 and Comparative Examples 7 to 8 Using the above resins, cylinders i and iii (PET layer cylinder) of a multilayer sheet molding machine manufactured by Plastic Research Laboratory
275 ° C setting, cylinder ii (middle layer cylinder), 2
Laminated and single-layer unrolled unsorted sheets having a thickness of 250 μm were formed at 75 ° C. and 295 ° C., hot runner set at 280 ° C., and chill roll set at 17 ° C. Next, using this sheet, a biaxially stretched film having a stretching ratio of 3 × 3 times was set at a stretching temperature setting of 90 to 170 ° C. at 5 ° C. intervals using a TM-LONG company's drawing film forming machine. Table 4 shows the stretching range of each resin from the molding conditions at this time.

[0035]

[Table 4]

When the temperature is lower than the stretching temperature range shown in Table 4, uneven orientation accompanied by neck stretching or microvoids due to cold stretching occurs. When the temperature is higher than this stretching temperature, an appropriate orientation is gradually obtained. In this case, draw stretching was not performed, and in any case, defects such as uneven thickness and wrinkles were observed on the appearance of the stretched body at a temperature lower by 5 ° C. to 10 ° C. than at the above stretching temperature and at a high temperature side. As shown in Table 4, in the case of a laminate of PET and the copolyester resin (B), stretching can be performed at a stretching temperature equivalent to that of PET, and a PET film stretching apparatus widely used industrially at present is used. It can be widely used and has excellent characteristics in molding.

[0037]

The multilayer molded film and sheet of the present invention have excellent gas barrier properties, mechanical strength, transparency and moldability, and can be used industrially.

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Takuma Kobayashi 10-24 Toyo-cho, Tsuruga-shi, Fukui Prefecture Toyobo Co., Ltd.

Claims (1)

[Claims] 1. A polyethylene terephthalate resin (A)
A polyester multilayer film or sheet comprising at least one layer and at least one layer of a copolymerized polyester resin (B) having 40 to 90 mol% of ethylene-2,6-naphthalate units and 60 to 10 mol% of ethylene isophthalate units, The composition ratio (A) :( B) is 10 to 90% by weight to 1
0 to 90% by weight of a polyester multilayer film or sheet.