JPH02135259A - Blow molded article of polyester - Google Patents

Abstract

PURPOSE:To provide a blow molded polyester article having excellent gas- barrierness and transparency and having at least one layer consisting of a mixture of a thermoplastic polyester, a polyamide containing m-xylylene group and a specific modified polyester. CONSTITUTION:The objective blow molded polyester article has at least one layer composed of a mixture of (A) a thermoplastic polyester preferably containing ethylene terephthalate as main recurring unit and having an intrinsic viscosity of >=0.55, (B) a polyamide containing m-xylylene group and having a relative viscosity of >=1.5, preferably 2-4 (e.g., poly-m-xylylene adipamide) and (C) a modified polyester containing 0.5-10mol% of a copolymerized component having a metal sulfonate group (preferably ethylene isophthalate containing metal sulfonate group), preferably a modified polyester containing ethylene terephthalate unit accounting for >=90mol% of the constituent unit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a polyester hollow molded article having excellent gas barrier properties and transparency. More specifically, it has a layer consisting of a mixture of a thermoplastic polyester resin, a metaxylylene group-containing polyamide resin, and a compatibilizer that uniformly and finely disperses the metaxylylene group-containing polyamide resin in the thermoplastic polyester resin, and has gas barrier properties and transparency. This invention relates to a polyester hollow molded article with excellent properties.

[Conventional technology]

Thermoplastic polyester resins, mainly made of polyethylene terephthalate, have traditionally been used in various types due to the material's excellent mechanical properties, male barrier properties, chemical resistance, fragrance retention, transparency, hygiene, and safety. It is processed into containers, films, sheets, etc., and is widely used as packaging material. Particularly in recent years, advances in blow molding technology, especially biaxial stretch blow molding technology, have led to remarkable advances in the use of hollow containers such as bottles and cans.

However, biaxially oriented containers made of thermoplastic polyester resin mainly composed of polyethylene terephthalate do not have perfect performance, especially for foods and pharmaceuticals whose contents require high gas barrier properties. It was unsuitable as a container due to its insufficient gas barrier properties against oxygen.

[Problem to be solved by the invention]

Conventionally, resins with excellent gas barrier properties have been used to improve the gas barrier properties of plastic containers, such as polyvinyl alcohol (Japanese Patent Application Laid-open No. 114572/1983), vinylidene chloride resin (Japanese Patent Application Laid-open No. 155759/1989), and ethylene.・Vinyl alcohol resin (JP-A-56-7
7143)) are known. However, interlayer adhesion is weak due to lack of compatibility with polyester resin, bonding force, reaction force, etc., resulting in insufficient mechanical strength as a container and permeation gas remaining between the layers. Furthermore, it has drawbacks such as a lack of durability in water resistance and gas barrier properties. Attempts have also been made to obtain containers with excellent gas barrier properties by blending gas barrier resins and thermoplastic resins. However, even in this case, it has drawbacks such as lack of water resistance, loss of stretchability, lack of transparency due to pearl-like devitrification, and insufficient gas barrier properties. However, satisfactory results have not yet been obtained.

In addition, an attempt has been made to improve the gas barrier properties by blending a metaxylylene group-containing polyamide resin with a thermoplastic polyester resin (Japanese Patent Application Laid-Open No. 73966/1982), but transparency is impaired due to poor compatibility, and It has problems in that it lacks water resistance and stretchability, and its barrier properties are significantly reduced when it absorbs moisture, so its uses are limited.

[Means to solve the problem]

As a result of intensive research by the present inventors to solve the above problems,
Improves barrier properties against oxygen without impairing the excellent mechanical properties of thermoplastic polyester resin, and without impairing transparency even when blended, and barrier properties and transparency are not affected by moisture. It was discovered that a hollow molded body can be obtained by adding a meta-xylylene group-containing polyamide resin and a specific copolymerized polyester as a compatibilizer, and the present invention was gradually completed. That is, the present invention provides a hollow molded article consisting of a single layer or multiple layers,
A polyester characterized in that at least one layer is composed of a mixture of a thermoplastic polyester ◇υ, a metaxylylene group-containing polyamide ■, and a modified polyester (Q) containing 0.5 to 10 mol% of a copolymer component having a sulfonic acid metal base. It is a hollow molded body.

The thermoplastic polyester recovered in the present invention includes acid components such as terephthalic acid, isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, naphthalene 1,4- or 2,6-dicarboxylic acid, adipic acid, sebacic acid, Deccan 1. IO-dicarboxylic acid, hexahydroterephthalic acid, glycol components such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclobexane dimetatool, 2,2'-bis(4-hydroxyphenyl) Propane, 2,2'-bis(4-hydroxyethoxyphenyl)propane or oxyacid obtained from p-oxybenzoic acid, p-hydroethoxybenzoic acid, etc.
In the present invention, the main repeating unit is ethylene terephthalate, in which 80 mol% or more of the acid component is terephthalic acid, preferably 90 mol% or more, and 80 mol% or more, preferably 90 mol% or more of the glycol component is ethylene glycol. Preferred are polyesters.

The thermoplastic polyester of the present invention has an intrinsic viscosity of 0.55 or more, more preferably 0.65 to 1.4. If the intrinsic viscosity is less than 0.55, it is difficult to obtain a parison, which is a precursor molded body of a container, in a transparent amorphous state, and the resulting container also has insufficient mechanical strength.

In addition, the metaxylylene group-containing polyamide used in the present invention as component (1) includes metaxylylene diamine,
Or, in the molecular chain, a constituent unit produced from meta-xylylene diamine, a mixed xylylene diamine containing 30% or less of the total amount of para-xylylene diamine, and an α1 ω-aliphatic dicarboxylic acid having 4 to 10 carbon atoms. at least 7 to
Examples include polymers containing 0 mol%.

Examples of these polymers include homopolymers such as polymethaxylylene adipamide, polymethaxylylene adipamide, polymethaxylylene adipamide, etc., and metaxylylene/paraxylylene adipamide copolymers, metaxylylene adipamide, etc. Copolymers such as /paraxylylene adipamide copolymer, metaxylylene/paraxylylene adipamide copolymer, etc., and components of these homopolymers or copolymers such as hexamethylene diamine. Aliphatic diamines, cycloaliphatic diamines such as piperazine, parabis(
aromatic diamines such as 2-aminoethyl)benzene,
Aromatic dicarboxylic acids such as terephthalic acid, lactams such as ε-caprolactam, ω-aminocarboxylic acids such as γ-aminohebutanoic acid, aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid, etc. Examples include copolymerized copolymers. In the above copolymer, para-xylylene diamine is 30% of the total xylylene diamine.
% or less, and the constituent units produced from xylylene diamine and aliphatic dicarboxylic acid account for at least 70 mol % or more in the molecular chain.

Meta-xylylene group-containing polyamide (hereinafter abbreviated as MXD6 resin) itself is inherently brittle in an amorphous state, so it is usually necessary that the relative viscosity is 1.5 or more, preferably 2.
It is 0 to 4.0.

The zero-component copolyester in the present invention contains 0.5 to 10 mol% of the copolymer component having a sulfonic acid metal base.
It has molecular compatibility with the thermoplastic polyester, finely disperses the MXD6 resin, and significantly improves the transparency of molded products obtained from the polyester resin composition. Preferably, at least 90 mol% of the structural units are ethylene terephthalate, and 0.5 to
This is a copolymerized polyester in which 10 mol% is a copolymerized component having a sulfonic acid metal base.

Specifically, the above-mentioned copolymerized polyester is manufactured from the raw materials exemplified for the above-mentioned thermoplastic polyester (A) and a copolymerized component having a sulfonic acid metal base represented by the following general formula (1).

The sulfonic acid metal salt compound may be any compound as long as it is represented by the general formula (1), but 5
-sodium sulfoisophthalate, dimethyl 5-sodium sulfoisophthalate, bis(2-hydroxyethyl) 5-sodium sulfoisophthalate or bis(4-hydroxybutyl) 5-sodium sulfoisophthalate are preferred.

M in the general formula representing a sulfonic acid metal salt compound represents an alkali metal such as sodium, potassium, calcium, pallium, lithium, magnesium, strontium, alkaline earth metal, or lead, lanthanum, zinc, etc. Preferred metals are sodium, lithium, and potassium, and particularly preferred metal is sodium.

The amount of the sulfonic acid metal salt compound added is 0.5 to 10 mol%, preferably 1.0 to 10 mol%, based on the polyester.
The range is 5.0 mol%.

The intrinsic viscosity of the obtained copolymerized polyester is preferably 0.40 or more, more preferably 0.50 to 1.4.

The above-mentioned molecular compatibility means that the kneaded compositions are mixed on the molecular order, and that the glass transition point obtained from DSC or viscoelasticity measurement is substantially one.

In the prisoner component in the present invention, (the amount of the Q component varies depending on the type of the balance component, but the S) component is 1 to 100 parts by weight, preferably 5 to 60 parts by weight, based on 100 parts by weight of the prisoner component, (13) Mixing ratio of component to component is 95:5
-5:95, especially 80:20-40:60 is preferred.

Additives such as antioxidants, ultraviolet absorbers, antistatic agents, and transparent colorants may also be added to the above mixture, if necessary.

Next, the method for mixing the components (Q) is not particularly limited and may be carried out by any method. For example, each component may be mechanically kneaded using an extruder, roll mill, Banbury mixer, etc. Alternatively, multi-stage kneading may be used in which the copolyester is kneaded in advance with MXD&resin, and then the thermoplastic polyester component is kneaded.

The gas barrier hollow molded body of the present invention can be obtained by tri-blending the components (4) to 0 at a desired concentration and molding the mixture directly in a hollow body molding machine, or by melt-kneading each component in an extruder. Examples include a method of making mixed composition pellets and molding the pellets with a blow molding machine.

Regarding molding using a blow molding machine, it can be carried out in no way different from conventional blow molding of polyester resin. For example, extrusion blow molding is generally called direct blow molding, injection blow molding is a method in which the parison is blown with compressed gas before it has been sufficiently cooled after injection molding, and biaxial stretch blow molding is also known as injection molding or injection blow molding. After producing a parison with a bottomed opening by extrusion molding, the parison is stretched using a stretch blowing device. The temperature is adjusted to an appropriate temperature, for example, 70 to 150°C, and axial stretching by a stretching rond and circumferential stretching by compressed gas are performed simultaneously or sequentially. A blow molding method can be used.

Further, the hollow molded article of the present invention may be composed of multiple layers,
It is sufficient that at least one layer thereof is composed of a mixture of the above (A), (B), and (C).

[For production]

In the hollow molded article of the present invention, the thermoplastic polyester and the zero copolymer polyester have molecular compatibility, and
Since the Tg of each component in C) is almost the same, oriented crystallization is sufficiently induced by stretching, so the excellent mechanical properties of thermoplastic polyester are not possessed by any one member, and the oxygen gas barrier property is maintained. can be significantly improved.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

The methods for measuring the main characteristics measured in the present invention are shown below. However, the oxygen permeation rate was measured using the bottle, and other items were measured using a test piece cut from the main body of the bottle.

(1) Intrinsic viscosity of polyester [η]; Phenol/
Measurement was performed at 30°C using a mixed solvent of tetrachloroethane = 6/4 (weight ratio).

(2) M X D, ηrel of resin; 9 for 1 g of resin
Relative viscosity measured at 25°C, dissolved in 100+ nl of 6% sulfuric acid.

(3) Transparency and haze °: Using haze meter MODEL TC-HI manufactured by Tokyo Denshoku Co., Ltd., JIS-6
It was calculated from the following formula according to 714.

Transparency”” T z / T IX 100 (%)T
, Amount of light emitted by two persons T2: Amount of total light transmission T3: Amount of scattered light by the device T4: Amount of scattered light by the device and sample (4) Amount of oxygen permeation; US MODERN C0NTR0L
From the oxygen permeation meter OX-TRAMiOO made by S company,
The permeation amount per 1000cc bottle was measured at 20"C.

(5) Tensile properties: Using a tanzag-shaped specimen with a width of 10 mm, the stratified strength and breaking strength and elongation were measured using a Tensilon manufactured by Toyo Baldwin Co., Ltd. under conditions of a chuck gap of 50 bars and a tensile speed of 50 mm/min. (23''C) Examples 1 to 6, Comparative Examples 1 to 3 A copolymerized polyester in which 95 mol% of the structural units were ethylene terephthalate and 5 mol% was 5-sodium sulfoisophthalate was used as the component.

Next, as the polyester which is the prisoner component, [η]=0.8(
C) Polyethylene terephthalate (abbreviated as PET)
MXD is the component, and ηrel is the resin.
Using the polymethaxylylene adipamide of 2.2, knead the above zero copolymer polyester as each component in the proportions shown in Tables 1 and 2 to obtain pellets, and use the obtained pellets to produce Meiki Seisakusho. A bottomed parison with an outer diameter of 25+ nm, a length of 130 mm, and a wall thickness of 4 mm was molded using an M100 injection molding machine manufactured by Kogyo Corporation. The open end of this parison was fitted into a parison fitting part equipped with a rotation drive device, and the parison was heated while rotating in an open space equipped with a far-infrared heater until the surface temperature of the parison reached 110°C. After this, the parison is transferred into the blow mold and the drawing speed is 2.
Blow molded under the conditions of 2 cm/sec and compressed gas pressure of 20 kg/ci, total length 265 mm, body outer diameter 80 mm,
A beer bottle-shaped hollow container with an internal volume of 1000 was obtained.

The performance of these containers is shown in Table 1.2.

(Margins below this page) As is clear from Table 1, the hollow molded article of the present invention has significantly improved transparency and gas barrier properties. It should be noted that when the haze value reaches 15, the transparency of the bottle changes greatly in terms of appearance.

(Margins below this page) As is clear from Table 2, it can be seen that the hollow molded article of the present invention has improved its gas barrier properties and the significant decrease in transparency upon moisture absorption.

Examples 7 to 10 Molded bodies were obtained in the same manner as in Example 3, except that in Example 3, a copolyester having the composition shown in Table 3 was used as the zero-component copolyester. The results are also listed in Table 3.

(Margins below this page) As is clear from Table 3, the use of polyester copolymerized with 5-sodium sulfoisophthalic acid as the Q component improves transparency and significantly reduces haze.

〔Effect of the invention〕

The hollow molded article of the present invention having the above configuration has excellent transparency, gas barrier properties, and mechanical properties, and has almost no influence from moisture (water), as its effects have been demonstrated in the examples. It is extremely durable as a container that does not receive water.

Claims (3)

[Claims] (1) In a hollow molded body consisting of a single layer or multiple layers,
At least one layer is made of a mixture of a thermoplastic polyester (A), a metaxylylene group-containing polyamide (B), and a modified polyester (C) containing 0.5 to 10 mol% of a copolymer component having a sulfonic acid metal base. Characteristic polyester hollow molded body. (2) The polyester blow molded article according to claim 1, wherein the main repeating unit of the thermoplastic polyester (A) is ethylene terephthalate. (3) Polyester blow molding according to claim 2, characterized in that at least 90 mol% of the structural units of the modified polyester (C) are ethylene terephthalate, and the copolymerization component is ethylene isophthalate containing a sulfonic acid metal base. body.