JP2674193B2 - Polyester composition, polyester stretched sheet comprising the same, and polyester hollow container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester composition having high transparency and excellent strength and gas barrier properties, and a packaging material molded using the same.

[Conventional technology]

Polyethylene terephthalate is excellent in mechanical strength, chemical stability, transparency, hygiene, etc., and because it is lightweight and inexpensive, it is widely used for various sheets and containers as packaging materials, especially recently, Demand for carbonated drinks, fruit juice drinks, liquid seasonings, cooking oils, sake and wine containers is growing rapidly.

However, although the gas barrier property of polyethylene terephthalate is superior to that of other resins such as polyolefin, there are some fields in which a higher level is required, and it cannot be said to be a sufficient level. For example,
In applications such as carbonated drinks, beer, wine, etc., a particularly strict oxygen gas barrier property and carbon dioxide gas barrier property are required from the viewpoint of storage of contents, and a hollow container made of commonly used biaxially oriented polyethylene terephthalate. However, it cannot be said that it has a sufficient gas barrier property.

For this reason, gas barrier containers in which polyethylene isophthalate or its copolyester is blended with polyethylene terephthalate have been proposed to further improve the gas barrier properties of polyethylene terephthalate containers (JP-A-59-64658 and JP-A-59-64658). 61-43655). However, the level of gas barrier property of these polyesters is not yet sufficient, and it is necessary to blend a considerable proportion in order to significantly improve the gas barrier property of polyethylene terephthalate. The original strength and heat resistance are sacrificed.

In general, as materials having high gas barrier properties, polyvinylidene chloride, saponified ethylene-vinyl acetate copolymer, polyamide, and the like are known, but these gas barrier materials have poor compatibility with polyethylene terephthalate. Also, since the difference in the refractive index is large, the transparency of the blend is significantly impaired.

[Object of the invention]

An object of the present invention is to provide a polyester composition having excellent physical properties such as mechanical strength and gas barrier property and having high transparency, and a sheet and a container made of the same.

[Configuration of the invention]

The present invention provides a dicarboxylic acid containing 20 to 95% by weight of polyethylene terephthalate, (a) isophthalic acid or an ester-forming derivative thereof, and (b) a dicarboxylic acid represented by the following general formula (I) or an ester-forming derivative thereof. A polyester composition comprising 80 to 5% by weight of a copolyester obtained by copolymerizing an acid component with a diol component, wherein the ratio of (a) and (b) in the copolyester is (a): (B) = 10
To 95:90 to 5 (mol% ratio), and the sum of (a) units and (b) units represents the total acid component of the copolyester.
It relates to a polyester composition characterized by being 50 mol% or more.

Further, a sheet having excellent gas barrier properties obtained by stretching a sheet obtained by injection molding or extrusion molding of the polyester composition, and a gas barrier property obtained by further stretch-blowing the polyester composition, The present invention relates to a hollow container having excellent transparency and mechanical strength.

(In the formula, R is a halogen, an alkoxy group, a phenyl group,
Alternatively, it represents a substituent selected from an alkyl group. n is 0
-4. Of R in the general formula (I), the alkoxy group preferably has 1 to 2 carbon atoms, and particularly preferably a methoxy group. The alkyl group preferably has 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group.

Specific examples of the dicarboxylic acid represented by the general formula (I) include 1,2-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, 1,4-phenylenedioxydiacetic acid,
2-methyl-1,3-phenylenedioxydiacetic acid, 5-methyl-1,3-phenylenedioxydiacetic acid, 6-methyl-1,3
-Phenylenedioxydiacetic acid, 5-ethyl-1,3-phenylenedioxydiacetic acid, 6-ethyl-1,3-phenylenedioxydiacetic acid, 5-methoxy-1,3-phenylenedioxydiacetic acid, 6 Examples include -methoxy-1,3-phenylenedioxydiacetic acid, 4-chloro-1,2-phenylenedioxydiacetic acid, and 4-chloro-1,3-phenylenedioxydiacetic acid. Of these, preferred is a derivative of 1,3-phenylenedioxydiacetic acid, and more preferred is 1,3-phenylenedioxydiacetic acid.

The dicarboxylic acid represented by the general formula (I) may be used as it is in combination with isophthalic acid, or may be used as an ester-forming derivative such as an acid anhydride, an acid halide, a monoester or a diester. Further, it may be added after reacting with glycols to form a quantified product.

Isophthalic acid may also be used in the form of an ester derivative such as dimethyl isophthalate and diethyl isophthalate, and an ester-forming derivative which reacts with a diol component such as isophthalic acid halide such as isophthalic chloride.

In the copolyester used in the polyester composition of the present invention, the molar percentage of (a) isophthalic acid unit and (b) dicarboxylic acid unit represented by the general formula (I) is 10 to 95:90 to 5 , Preferably in the range of 30-90: 70-10. When the amount of the dicarboxylic acid unit represented by the general formula (I) used exceeds this range, the glass transition point (Tg) of the obtained copolyester is too low, and the resin before drying is dried. And the heat resistance of the resulting copolymerized polyester when blended with polyethylene terephthalate to form a molded article decreases. On the other hand, when the amount of the dicarboxylic acid unit represented by the general formula (I) used is less than this range, the level of gas barrier property is not sufficient, so that the gas barrier property of polyethylene terephthalate is improved to improve the gas barrier property of the present invention. It is not suitable for use as a polyester packaging material with excellent gas barrier properties.

In the copolyester used in the polyester composition of the present invention, the sum of the isophthalic acid unit and the dicarboxylic acid unit represented by the general formula (I) preferably accounts for at least 50 mol% or more of the repeating units of all acid components. .
If the sum of both is less than 50 mol%, the copolyester cannot be used as the packaging material of the present invention because the gas barrier property is not sufficient. Further, other dicarboxylic acids and oxyacids can be used as long as the isophthalic acid and the dicarboxylic acid represented by the general formula (I) satisfy the above molar ratio.

These dicarboxylic acids include terephthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenoxyethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid and their structural isomers, malonic acid. Examples of aliphatic dicarboxylic acids such as succinic acid and adipic acid, and oxyacids include hydroxybenzoic acid derivatives and glycolic acid.

Examples of the diol component used in the copolymer polyester used in the polyester composition of the present invention include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol and hexamethylene. Examples thereof include glycol, neopentyl glycol, cyclohexanedimethanol, diethylene glycol, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S. Of these, ethylene glycol is generally most preferred.

Further, the copolyester used in the present invention is a polyfunctional compound such as trimethylolpropane, pentaerythritol, glycerin, trimellitic acid, trimesic acid, and pyromellitic acid, and O-benzoyl within a range not impairing the requirements of the present invention. A monofunctional compound such as benzoic acid may coexist. Such polyfunctional compounds and monofunctional compounds are used within the range of 20 mol% or less of the diol component.

The copolyester used in the present invention has an intrinsic viscosity [phenol / tetrachloroethane (weight ratio 1 /
Value measured at 30 ° C using the mixed solvent of 1)] is 0.4 to 2.
It is desirable that the range is 0, preferably 0.50 to 1.5. When the intrinsic viscosity is less than 0.4, the strength of the obtained polyester is low, and after the completion of the polymerization reaction, when it is taken out from the reaction can and cut into chips, or when blended with polyethylene terephthalate, a film or sheet, a bottle, a barrel, a can, etc. Physical properties required for practical use cannot be obtained when molding as a container.
When the intrinsic viscosity exceeds 2.0, there is a problem that the melt viscosity becomes too high and molding such as injection, extrusion and blow becomes difficult.

The copolymerized polyester can be produced by a conventionally known polymerization method for polyethylene terephthalate. For example, isophthalic acid and a dicarboxylic acid represented by the general formula (I), specifically 1,3-phenylenedioxydiacetic acid, and ethylene glycol are used to carry out a direct esterification reaction under pressure, and then further elevate. There is a method in which the polycondensation reaction is performed by gradually reducing the pressure while heating. Alternatively, an ester derivative of isophthalic acid, for example, isophthalic acid dimethyl ester, and an ester derivative of dicarboxylic acid represented by the general formula (I), for example, 1,3-phenylenedioxydiacetic acid dimethyl ester, and ethylene glycol are used. It can be produced by carrying out an exchange reaction and then further polycondensing the obtained reaction product. At that time, it is preferable to use an esterification catalyst, a transesterification catalyst, a polycondensation catalyst, a stabilizer and the like.

As the transesterification catalyst, known compounds, for example,
From the viewpoint of transparency, one or more kinds of calcium, manganese, zinc, sodium, and lithium compounds can be used, and a manganese compound is particularly preferable. As the polymerization catalyst, one or more known antimony, germanium, titanium, and cobalt compounds can be used, but antimony, germanium, and a titanium compound are preferably used.

In the present invention, if necessary, conventionally known additives such as antioxidants, ultraviolet absorbers, fluorescent brighteners, release agents, antistatic agents, dispersants and coloring agents such as dyes and pigments may be added. It may be added at any stage during polyester production, or may be added by so-called masterbatch disposal before molding.

The copolymerized polyester used in the polyester composition of the present invention thus obtained is melt-molded with polyethylene terephthalate to obtain a molded article. In particular,
It is also possible to blend with polyethylene terephthalate and melt-knead with an extruder to obtain a mixed chip, and then use this for molding, or dry-blend each component and directly use for molding. Here, the ratio of the blend of polyethylene terephthalate and the copolyester of the present invention is such that the copolymer is 5 to 5 in the composition.
It preferably represents 80% by weight. The ratio of copolymer is 5
When it is less than 80% by weight, the effect of improving the gas barrier property of polyethylene terephthalate is insufficient, and when it exceeds 80% by weight, the performance of the molded product deteriorates in terms of mechanical strength and heat resistance.

The polyester composition of the present invention can be used to mold films, sheets, containers, and other packaging materials using a melt molding method generally used for molding polyethylene terephthalate and the like, and is a gas barrier even in an unstretched state. It can be used as a highly flexible material. Further, the gas barrier properties and mechanical strength can be further improved by stretching the polyester composition in at least one axial direction.

A stretched sheet comprising the polyester composition of the present invention,
The polyester composition of the present invention formed into a sheet by injection molding or extrusion molding is uniaxially stretched, which is usually used for stretching polyethylene terephthalate, sequential biaxial stretching, simultaneous 2
It is molded using any stretching method of axial stretching. Further, it can be formed into a cup shape or a tray shape by pressure forming.

In producing a stretched sheet comprising the polyester composition of the present invention, the stretching temperature may be set between the glass transition point temperature of the polyester of the present invention or a temperature 70 ° C. higher than the glass transition point. The stretching ratio is usually from 1.1 to 10 times, preferably from 1.1 to 8 times in the case of uniaxial stretching, and in the case of biaxial stretching, from 1.1 times in both the longitudinal and transverse directions. It may be carried out in a range of 8 times, preferably 1.1 times to 5 times. The stretched sheet obtained from the polyester composition of the present invention thus obtained is excellent in transparency, gas barrier property and mechanical strength, and is useful as a film-shaped, cup-shaped or tray-shaped packaging material.

The polyester hollow molded article made of the resin composition of the present invention is formed by stretch blow molding a preform, and an apparatus conventionally used in blow molding of polyethylene terephthalate can be used. Specifically, for example, a preform is once formed by extrusion blowing method, injection blowing method, injection molding or extrusion molding, and as it is, or after processing the plug portion and the bottom portion, reheat it, A blow molding method such as a hot parison method or a cold parison method for stretching is applied. The stretching temperature is 70 to 120 ° C,
The stretching ratio is preferably 80 to 110 ° C., and the stretching ratio is 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction.

Further, in producing a polyester hollow molded article, a preform is formed by laminating a layer made of the polyester composition of the present invention and a layer made of polyalkylene terephthalate containing polyethylene terephthalate as a main component, which is then biaxially stretch blow molded. Then, a multi-layer hollow molded container may be used. At this time, the layer structure is not particularly limited, and 3
A structure of about 5 layers is preferable.

〔Example〕

Hereinafter, the present invention will be described in more detail by examples,
The present invention is not limited to the following examples unless it exceeds the gist.

In the examples, "parts" means "parts by weight", and various measuring methods used in the examples are shown below.

Intrinsic viscosity phenol-tetrachloroethane (50/50 weight ratio)
It was measured at 30 ° C in the middle.

Oxygen permeability Extruded sheet samples with a thickness of about 200μ and bottles were prepared, and under the conditions of 23 ° C and 100% RH, "OX-TRAN 10 / 50A"
Measured with an oxygen permeability measuring device (manufactured by US Modern Controls), cc · mm / m ² · day · atm or cc / bottle · day · atm
Indicated by

Production Example 1 38 parts of dimethyl isophthalate, 48 parts of naphthalene dicarboxylic acid dimethyl ester, 48 parts of ethylene glycol, and 0.03 part of manganese acetate tetrahydrate were added to a reaction vessel and heated to 160 ° C.
To 230 ° C., and the transesterification reaction was carried out until no effluent came out.

59 parts of 1,3-phenylenedioxydiacetic acid, 0.02 parts of orthophosphoric acid, and 0.03 parts of germanium dioxide were added to this system in this order, and the temperature inside the polymerization tank was gradually reduced from 230 ° C. while gradually increasing the temperature. A highly transparent polyester having an intrinsic viscosity of 0.71 was obtained after a total polymerization time of 6 hours under a vacuum of 260 ° C. and 0.5 torr.

Production Example 2 Polymerization was performed in the same manner as in Production Example 1 except that 52 parts of dimethyl isophthalate, 30 parts of 1,3-phenylenedioxydiacetic acid, 65 parts of naphthalene dicarboxylic acid dimethyl ester, and 66 parts of ethylene glycol were used. . The intrinsic viscosity of the obtained polymer was 0.69.

Production Example 3 51 parts of dimethyl isophthalate, 89 parts of 1,3-phenylenedioxydiacetic acid, 33 parts of ethylene glycol, and 0.03 part of titanium tetrabutoxide were added to a reaction can, and the temperature was gradually raised from 200 ° C to 230 ° C. Then, the transesterification reaction was carried out until no effluent came out.

Further, the temperature was gradually raised from 230 ° C., and the pressure inside the polymerization tank was gradually reduced from normal pressure to obtain a highly transparent polyester having an intrinsic viscosity of 0.65 under a vacuum of 260 ° C./torr and a total polymerization time of 5.0 hours.

Production Example 4 Polymerization was performed in the same manner as in Production Example 1 except that 82 parts of dimethyl isophthalate, 32 parts of 1,3-phenylenedioxydiacetic acid, 34 parts of dimethyl ester of nanaphthalenedicarboxylic acid, and 70 parts of ethylene glycol were used. It was The intrinsic viscosity of the obtained polymer was 0.70.

Production Example 5 Polymerization was performed in the same manner as in Production Example 1 except that 114 parts of dimethyl isophthalate, 33 parts of 1,3-phenylenedioxydiacetic acid, 0 part of dimethyl naphthalene dicarboxylic acid, and 73 parts of ethylene glycol were used. . The intrinsic viscosity of the obtained polymer was 0.68.

Comparative Production Example 1 Polyethylene isophthalate was polymerized in the same manner as in Production Example 1 except that 152 parts of dimethyl isophthalate and 97 parts of ethylene glycol were used. The intrinsic viscosity of the obtained polymer was 0.73.

The copolymerized polyesters obtained in Production Examples 1 to 5 and Comparative Production Example 1 were pressed into a sheet of about 200 μm and the oxygen permeability was measured. The results are summarized in Table 1.

Examples 1-2 The copolymerized polyesters obtained in Production Examples 1-2 were melt-kneaded with polyethylene terephthalate having an intrinsic viscosity of 0.75 (Japan Unipet Co., Ltd. RT543C) at a ratio shown in Table 2 below,
The blend was pressed into sheets of about 200μ. The results of measuring the acid transmittance of the obtained press sheet are shown in Table 2.

Examples 3 to 4 The copolymerized polyester obtained in Production Example 1 was pellet-blended with polyethylene terephthalate (RT543C manufactured by Nippon Unipet) in the proportions shown in Table 2 below, and injection-molded (Nikko.
A 6 cm × 6 cm flat plate was molded by 8 oz injection molding.
This was simultaneously stretched 3 times in the longitudinal and transverse directions with a long stretching machine to obtain a stretched sheet having a thickness of about 100 μ, and the oxygen permeability was measured. The results are summarized in Table 2.

Comparative Examples 1-2 Polyethylene terephthalate (RT54 manufactured by Nippon Unipet Co., Ltd.
For 3C), the oxygen permeability of the unstretched film was measured in the same manner as in Examples 1 and 2. Further, a stretched film was prepared in the same manner as in Examples 3 to 4, and the oxygen transmission rate was measured. Table 2 shows the results.

Comparative Examples 3 to 4 The polyethylene isophthalate obtained in Comparative Production Example 1 was blended with polyethylene terephthalate in the same manner as in Examples 1 and 2, and the oxygen permeability of the unstretched film was measured. Further, a stretched film of a blend with polyethylene terephthalate was prepared in the same manner as in Examples 3 to 4,
This oxygen permeability was measured. Table 2 shows the results.

Example 5 10 parts of the polyester copolymer obtained in Production Example 1 was mixed with polyethylene terephthalate (RT543C manufactured by Nippon Unipet) 90
Part is dry blended and injection molded into a bottle preform.
(Average thickness of shoulder and body 0.33mm, total surface area 700c
It was molded into a stretched bottle of m ² ). The oxygen gas permeability of the obtained bottle was measured and found to be 0.21 cc / bottle ・ day ・ atm.
Met.

Comparative Example 5 Polyethylene terephthalate (RT54 manufactured by Nippon Unipet)
3C) was used to mold a stretched bottle having an internal volume of 1.5 in the same manner as in Example 5. When the oxygen gas permeability of the obtained bottle was measured, it was 0.43 cc / bottle · day · atm.

Comparative Example 6 Polyethylene isophthalate obtained in Comparative Production Example 1
10 parts and polyethylene terephthalate (made by Nippon Unipet)
RT543C) using 90 parts in the same manner as in Example 5 with an internal volume of 1.5
Was formed. When the oxygen gas permeability of the obtained bottle was measured, it was 0.34 cc / bottle · day · atm.

Comparative Example 7 A bottle preform was injection-molded using the polyester copolymer obtained in Production Example 1, and this was molded into a stretched bottle having an internal volume of 1.5 by a biaxial stretching blow machine.
The shape of the obtained bottle was distorted and the strength of the bottle was low.

Production Example 6 25 parts of dimethyl isophthalate, 72 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester, 48 of ethylene glycol
Parts and 0.03 parts of manganese acetate tetrahydrate were added to the reaction can,
The temperature was gradually raised from 160 ° C. to 230 ° C., and transesterification was carried out until no effluent appeared.

To this system, 52 parts of 1,3-phenylenedioxydiacetic acid, 0.02 part of orthophosphoric acid, and 0.03 part of germanium dioxide were added in this order, and the temperature in the polymerization tank was gradually reduced from normal pressure while gradually increasing the temperature from 230 ° C. A highly transparent polyester having an intrinsic viscosity of 0.70 was obtained at 260 ° C. under a vacuum of 0.5 torr with a total polymerization time of 6 hours.

Production Example 7 In the same manner as in Production Example 1 except that 13 parts of dimethyl isophthalate, 75 parts of 1,3-phenylenedioxydiacetic acid, 65 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester and 66 parts of ethylene glycol were used. Polymerization was carried out. The intrinsic viscosity of the obtained polymer was 0.68.

Production Example 8 In the same manner as in Production Example 1 except that 29 parts of dimethyl isophthalate, 83 parts of 1,3-phenylenedioxydiacetic acid, 54 parts of 2,6-naphthalenedicarboxylic acid dimethyl ester and 73 parts of ethylene glycol were used. Polymerization was carried out. The intrinsic viscosity of the obtained polymer was 0.70.

The copolymerized polyester obtained in Production Examples 6 to 8 was used in an amount of about 200.
It was pressed into a sheet of μ and the oxygen transmission rate was measured. The results are summarized in Table 3.

Examples 6 to 7 The copolyesters obtained in Production Examples 6 to 7 were melt-kneaded with polyethylene terephthalate having an intrinsic viscosity of 0.75 (Japan Unipet Co., Ltd. RT543C) in a ratio shown in Table 4 below.
The blend was pressed into sheets of about 200μ. Table 4 shows the results of measuring the oxygen permeability of the obtained press sheet.
Shown in

Examples 8 to 9 Polyester copolymers obtained in Production Examples 6 and 7 were pellet-blended with polyethylene terephthalate (RT543C manufactured by Nippon Unipet) at a ratio shown in Table 4 below, and injection-molded (Nikko 0.8oz injection molding). A 6 cm × 6 cm flat plate was molded by. This was simultaneously stretched 3 times in the longitudinal and transverse directions with a long stretching machine to obtain a stretched sheet having a thickness of about 100 μ, and the oxygen permeability was measured. The results are summarized in Table 4.

Example 10 Polyethylene terephthalate (RT543C manufactured by Nippon Unipet) 80 parts was added to 20 parts of the polyester copolymer obtained in Production Example 6.
Part and dry-blended to injection mold a bottle preform.
(Average thickness of shoulder and body 0.33mm, total surface area 700c
It was molded into a stretched bottle of m ² ). The oxygen gas permeability of the obtained bottle was measured and found to be 0.21 cc / bottle ・ day ・ atm.
Met.

〔The invention's effect〕

The polyester composition of the present invention has high transparency and excellent gas barrier properties. Therefore, the stretched sheet obtained by using the film makes use of the gas barrier property,
It can be used for various uses as a packaging material such as sheets, cups and trays. Furthermore, in the polyester hollow molded article of the present invention, in addition to excellent transparency and gas barrier properties, it also has mechanical strength and soft drinks, seasonings, oil, beer and wine, alcoholic beverages such as sake,
It can be widely used for cosmetics and other applications. In particular, it can be used for applications such as small carbonated beverages, beer, wine, etc., where ordinary polyethylene phthalate biaxially stretched bottles have insufficient gas barrier properties and cannot be stored for a specified shelf life. Becomes

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Claims (4)

(57) [Claims] 1. Containing 20 to 95% by weight of polyethylene terephthalate, (a) isophthalic acid or an ester-forming derivative thereof, and (b) a dicarboxylic acid represented by the following general formula (I) or an ester-forming derivative thereof. A polyester composition comprising 80 to 5% by weight of a copolyester obtained by copolymerizing a dicarboxylic acid component with a diol component, wherein the ratio of (a) and (b) in the copolyester is (a). : (B) = 10
To 95:90 to 5 (mol% ratio), and the sum of the (a) unit and the (b) unit represents the total acid component of the copolyester.
A polyester composition comprising 50 mol% or more. (In the formula, R represents a substituent selected from a halogen, an alkoxy group, a phenyl group or an alkyl group. N is 0 to 4
Is an integer. ) 2. Containing 20 to 95% by weight of polyethylene terephthalate, (a) isophthalic acid or an ester-forming derivative thereof, and (b) a dicarboxylic acid represented by the general formula (I) or an ester-forming derivative thereof. A polyester composition comprising 80 to 5% by weight of a copolyester obtained by copolymerizing a dicarboxylic acid component with a diol component, wherein the ratio of (a) and (b) in the copolyester is (a). : (B) = 30
˜90: 70 to 10 (mole% ratio), and the sum of (a) units and (b) units represents the total acid component of the copolyester.
A polyester composition comprising 50 mol% or more. 3. A polyester stretched sheet obtained by injection-molding or extrusion-molding the polyester composition according to claim 1 and stretching a sheet-like material in at least one direction. 4. A polyester hollow container obtained by subjecting the polyester composition according to claim 1 to stretch blow molding or injection molding or extrusion molding of the composition to form a preform, followed by biaxial stretch blow molding. .