JPH02150420A - Polyester having excellent gas barrier property - Google Patents

Abstract

PURPOSE:To obtain the title polyester having excellent heat resistance and gas barrier properties by using phthalic naphthylenedicarboxylic acid or an ester forming derivative thereof as a dicarboxylic acid component and a glycol component having a specific repeating unit as a glycol component. CONSTITUTION:The aimed polyester consisting of repeating units shown by formula I and formula II (R is group shown by formula III, group shown by formula IV or mixture thereof; m is 2-10), comprising 0-95mol% group shown by formula I and 100-5mol% group shown by formula II. Preferably >=80mol% group shown by formula I is expressed by unit shown by formula V. The polyester has preferably >=60 deg.C glass transition temperature and 0.3-1.5 intrinsic viscosity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crystalline polyester having excellent gas barrier properties.

[Conventional technology]

Polyethylene terephthalate (hereinafter abbreviated as PET)
Because of its excellent mechanical and chemical properties, it is processed into various containers such as films, sheets, bottles, cups, and trays, and is widely used as a packaging material.

However, although PET is superior to polyethylene and polypropylene in terms of gas barrier properties against oxygen and carbon dioxide, it is still not sufficient, and further improvements in performance are desired in many applications.

For example, in containers with pressurized interiors such as carbonated beverages, the gas barrier performance of the conventionally known level is insufficient, and it is not possible to prevent the carbon dioxide gas in the container from gradually dissipating. In packaging, if oxygen is present inside, there are problems such as the contents being oxidized by ultraviolet rays during storage and deteriorating in quality. This has been an extremely serious problem in the past, especially for foods containing oil and fat components, but with the recent expansion of natural foods and health foods, the number of ``additive-free'' and ``low-sodium'' products has increased. As a result, the demand for gas barrier properties is becoming stronger even in general food packaging materials. A method for improving the gas barrier properties of PET as a packaging material is to coat or laminate it with a resin that has better gas barrier properties than PET, such as polyvinylidene chloride, saponified ethylene-vinyl acetate copolymer, polyamide, etc. However, all such resins have poor adhesion to PET, which not only causes delamination and loss of transparency of the container as a result, but is also disadvantageous in terms of recovery.

- In place of PET, a method has been proposed in which a polymer in which part or all of the terephthalic acid component of PET is replaced with isophthalic acid (Japanese Unexamined Patent Publication No. 5964624, R
, R, LightL et al. Polym, Engine, Sci
,.

22 (14), 857 (1982), etc.). However, satisfactory barrier properties have not been achieved even by methods using polyethylene isophthalate or copolymers thereof.

Also, as a method for improving the gas barrier properties of PET, there is a method of copolymerizing isophthalic acid and 1,3-bis(β-hydroxyethoxy)benzene to PET (Japanese Patent Laid-Open No. 5
8-167617) or a method of copolymerizing 1,3-phenylenedioxydiacetic acid with PET (Japanese Patent Publication No. 1983)
O-501Q6Q) etc. have been proposed. However, such copolymerized polyesters have extremely low glass transition temperatures, have completely insufficient heat resistance, and cannot be said to be of practical use.

On the other hand, there is a method in which polyethylene naphthalate-based polyester is laminated on PET (Japanese Unexamined Patent Publication No. 61-279553), and a method in which a condensed liquid crystal polymer is blended with polyethylene naphthalate (Japanese Unexamined Patent Publication No. 62-11).
No. 9265) have been proposed, but none of them have achieved satisfactory gas barrier performance.

[Problem to be solved by the invention]

In view of this situation, in which a polyester with high gas barrier properties has not yet been found, the present inventors set out to provide a new polyester with excellent gas barrier properties that cannot be achieved with conventional polyesters. As a result of intensive research, we have arrived at the present invention.

[Means to solve the problem]

The present invention relates to a polyester comprising repeating units represented by general formulas [I] and [II], and characterized in that OCH30 (1) is 0 to 95 mol% and CI is 100 to 5 mol%. This is what we provide.

The present invention will be specifically explained below.

The polyester of the present invention includes naphthylene dicarboxylic acid or its ester-forming derivative as a dicarboxylic acid component,
and 2.2-bis(4'-hydroxymethoxyphenyl)propane or its ester-forming derivative as a glycol component, a straight line in which m in the above general formulas [I] and [II] is an integer of 2 to 10. The constituent component is chain aliphatic glycol.

Among the dicarboxylic acid components, naphthylene dicarboxylic acid or its ester-forming derivative is 0 to 95 mol%, 2.2
-Bis(4'-hydroxymethoxyphenyl)propane or its ester-forming derivative is 100 to 5 mol%, but the moldability of the resulting polyester and the physical strength of molded products obtained from the polyester are affected. In consideration, it is preferable that the former be 30 to 95 mol% and the latter be 70 to 5 mol%.

When the amount of 2.2-bis(4'-hydroxymethoxyphenyl)propane or its ester-forming derivative is less than 5 mol %, the gas barrier performance of the molded article obtained from the polyester is not substantially improved.

The above-mentioned naphthylene dicarboxylic acid or its ester-forming derivative includes 2,6-naphthylene dicarboxylic acid,
1.4-naphthylene dicarboxylic acid or a mixture thereof is preferred, and in terms of heat resistance, gas barrier properties, moldability, etc., it is particularly preferred that 80 mol% or more of the acid is 2.6-naphthylene dicarboxylic acid.

In the polyester of the present invention, naphthylene dicarboxylic acid, 2,2-bis(4'-hydroxymethoxyphenyl)
Dicarboxylic acid components other than propane or their ester-forming derivatives in a proportion of 10 mol% or less, for example, aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid or their ester-forming derivatives, naphthylene dicarboxylic acid, 4゜4'-diphenyldicarboxylic acid, 1.2
- Aromatic dicarboxylic acids such as bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, phenylenedioxydiacetic acid, bis(4-carboxymethoxyphenyl)sulfone or their ester-forming derivatives, cyclohexanedicarboxylic acid Alicyclic dicarboxylic acids or ester-forming derivatives thereof, such as hydroxybenzoic acid, hydroxynaphthoic acid, hydroxyacetic acid, 3-hydroxypropionic acid, or ester-forming derivatives thereof, etc. may be used as copolymerization components. Can be done. As the ester-forming derivatives of the above dicarboxylic acids or oxycarboxylic acids, esters with lower alcohols such as methanol and ethanol are generally used, but esters with glycols such as ethylene glycol may also be used.

In the polyester of the present invention, the glycol component includes linear aliphatic glycols in which m is an integer of 2 to 10 in general formulas [I] and (II), such as ethylene glycol, tetramethylene glycol, hexamethylene glycol, octamethylene Glycols and the like can be mentioned, but glycols in which m is an integer of 2 to 4 are preferred, particularly ethylene glycol in which m is 2. Other glycol components, such as aliphatic glycols such as neopentyl glycol, alicyclic glycols such as 1,4-cyclohexane dimetatool, 1,3-bis(β-hydroxyethoxy ) Aromatic glycols such as benzene, bis(β-hydroxyethoxy)bisphenol S, and polymeric glycols such as polyethylene glycol and polypropylene glycol can be used as copolymerization components.

Further, the polyester of the present invention includes, for example, glycerin,
Trimethyl or higher polyfunctional compounds such as trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, pyromellitic acid, etc. may be copolymerized to the extent that melt molding is possible.

The polyester of the present invention can be produced by a method established for producing conventional polyethylene terephthalate. For example, it can be obtained by a method in which a dicarboxylic acid and a glycol are subjected to an esterification reaction followed by a polycondensation reaction, or a dicarboxylic acid ester and a glycol are subjected to a transesterification reaction and then subjected to a polycondensation reaction. Furthermore, among the dicarboxylic acid components, 2,2-bis(4'-hydroxymethoxyphenyl)propane or an ester-forming derivative thereof can be added after the esterification reaction or the transesterification reaction.

In this case, it is preferable to use an esterification catalyst, a transesterification catalyst, a polycondensation catalyst, a stabilizer, etc., but these catalysts, stabilizers, etc. are known as catalysts, stabilizers, etc. for polyester, especially polyethylene terephthalate. can be used. For example, catalysts that promote these reactions include metal compounds such as sodium, magnesium, calcium, zinc, manganese, tin, tungsten, germanium, titanium, and antimony, and stabilizers include phosphoric acid, phosphate esters, Examples include phosphorous compounds such as phosphorous acid and phosphorous esters. In addition, other additives (colorants, ultraviolet absorbers, light stabilizers, antistatic agents, flame retardants, etc.), fillers (silane,
Wollastonite, talc, calcium carbonate, mica, etc.) and reinforcing agents (glass fiber, etc.) can also be added.

The polyester obtained by the above method has an intrinsic viscosity of 0.3 to 1.5, preferably 0.4 to 1.2, and a glass transition temperature of 60°C or higher, preferably 70°C.
The above is preferable in terms of moldability and heat resistance.

The polyester of the present invention can be melt molded, and can be molded into sheets, films, or hollow containers by known molding methods, such as injection molding, blow molding, biaxial stretch blow molding, vacuum molding, and compression molding. can. The sheet or film can be formed into packaging materials such as wraps, bags, etc.

In addition, the polyester of the present invention can be used with other polymers such as polyolefin resins such as polyethylene and polypropylene,
It is also possible to laminate with polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon, etc., and laminates such as films, sheets, and tubes can be produced by coextrusion, dry lamination, sandwich lamination, etc. It is also possible to do this.

The molded article obtained from the polyester of the present invention has an oxygen permeability coefficient of 5 to 60% that of polyethylene terephthalate, for example.
, 6-85% of polyethylene-2,6-naphthalate, has excellent gas barrier performance, and has no moisture dependence on oxygen barrier properties, making it suitable for packaging when improved gas barrier properties are required. It is useful in applications such as

The present invention will be specifically explained below using Examples.

Note that parts in the examples mean parts by weight.

The physical property values of this example were measured according to the following method.

1) Intrinsic viscosity [η] Measured at 30°C at a concentration of lOg/12 using a mixed solvent of equal weight of phenol/tetrachloroethane.

2) Glass transition temperature Tg It was measured using a differential scanning calorimeter (manufactured by Mettler, Model TA-3000) at a heating rate of 10° C./min on a rapidly cooled amorphous sample.

3) Oxygen permeation amount Pot After drying the polymer at about 50°C under reduced pressure for at least 20 hours or more, extrude it at a temperature of 280°C using an extruder (Toyo Seiki Seisakusho new product, Labo Blast Mill), and immediately roll it on a chill roll (roll surface). Temperature: 30°C) to a thickness of 7.
A 5 μm non-oriented film was obtained. The film was measured using a gas permeability measuring device (manufactured by Tsunegi Seisakusho, GTRIO type),
Dry condition at 35°C (0%R,)1. ) was measured.

The unit is cc・20 μm/m”・day-atm.

Example 1 2.6-naphthalene dicarboxylic acid dimethyl ester 10
000 parts (95 mol%), 2,2-bis(4'-carboxinemethoxyphenyl)propane dimethyl ester 80
1 part (5 mol%), 6019 parts of ethylene glycol (molar ratio of ethylene glycol to dicarboxylic acid component is 2.2
5:1) and 2.6 parts of manganese acetate tetrahydrate were charged into a reactor, and the temperature was gradually raised from 190°C to 240°C over about 3 hours while stirring, and more than 99% of the theoretical amount of methanol was added. Distilled away. Thereafter, 0.9 parts of phosphorous acid and 4.2 parts of germanium dioxide were added, and polycondensation was carried out at 290° C. under high vacuum of 0.5 mmHg or less for about 2 hours. Table 1 shows the values of the intrinsic viscosity [η], glass transition temperature Tg, and oxygen permeation fi P Ot of the obtained polymer.

Example 2 A copolymerized polyester was produced in the same manner as in Example 1, except that the amount of modification with 2,2-his(4'-hydroxymethoxyphenyl)propane was changed from 5 mol% to 10 mol%. I got it. Table 1 shows the measured physical property values.

Example 3 A copolymerized polyester was produced in the same manner as in Example 1, except that the amount of modification with 2,2-bis(4'-hydroxymethoxyphenyl)propane was changed from 5 mol% to 20 mol%. I got it. Table 1 shows the measured physical property values.

Example 4 Example! A copolymerized polyester was obtained in the same manner as in Example 1, except that the amount of modification with 2,2-bis(4'-hydroxymethoxyphenyl)propane was changed from 5 mol% to 30 mol%. Table 1 shows the measured physical property values.

Example 5 A copolymerized polyester was produced in the same manner as in Example 1, except that the amount of modification with 2.2-bis(4″-hydroxymethoxyphenyl)propane was changed from 5 mol% to 50 mol%. The measured physical property values are shown in Table 1.

Example 6 In Example 1, the amount of modification with 2,2-bis(4'-carboxymethoxyphenyl)propane was changed from 5 mol% to 100%, that is, all of the dicarboxylic acid components were changed to 2,2-
A polyester was obtained in the same manner as in Example 1 except that bis(4'-hydroxymethoxyphenyl)propane was used.

Table 1 shows the measured physical property values.

Comparative Example 1 In Example 1, the amount of modification with 2,2-bis(4'-hydroxymethoxyphenyl)propane was changed from 5 mol% to 0 mol%, that is, all the dicarboxylic acid components were changed to 2,6-
Naphthalene dicarboxylic acid, final polymerization temperature 290℃
In the same manner as in Example 1 except that the temperature was changed from to 300°C,
Polyethylene-2,6-naphthalene dicarboxylate was obtained. Table 1 shows the measured physical property values.

Comparative Example 2 Polyethylene terephthalate was obtained in the same manner as in Example 1, except that terephthalic acid was used as the dicarboxylic acid component. Table 1 shows the measured physical property values. These results show that the polyester of the present invention has excellent gas barrier properties.

Table 1 [Effects of the Invention] The molded product obtained from the polyester of the present invention maintains heat resistance comparable to that of polyethylene terephthalate and has excellent gas barrier properties against oxygen and other gases, making it suitable for packaging materials that require improved gas barrier properties. It is useful as

Patent applicant RiRashi Co., Ltd. Representative Patent Attorney Ken Honda

Claims (7)

[Claims] (1) It is composed of repeating units represented by general formulas [I] and [II], ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・[I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼・...[II] (In the formula, R indicates ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲There are mathematical formulas, chemical formulas, tables, etc.▼, or a mixture thereof, and m is an integer from 2 to 10. ) [I] is 0 to 9
5 mol%, and [II] is 100 to 5 mol%. (2) 80 mol% or more of general formula [I] is ▲mathematical formula,
The polyester according to claim 1, which has a chemical formula, a table, etc.▼ (wherein m is an integer from 2 to 10). (3) In general formulas [I] and [II], m is 2 to 4
The polyester according to claim 1 or 2, wherein the polyester is an integer of . (4) The polyester according to any one of claims 1 to 3, having a glass transition temperature of 60°C or higher. (5) The polyester according to any one of claims 1 to 3, having an intrinsic viscosity of 0.3 to 1.5. (6) A film or sheet made of the polyester according to any one of claims 1 to 3. (7) A molded container made of the polyester according to any one of claims 1 to 3.