JPS58160344A - Hollow polyester molding having excellent gas barrier properties - Google Patents

Abstract

PURPOSE:To provide a hollow polyester molding having excellent gas barrier properties, by mixing a thermoplastic polyester resin with an m-xylylene group- contg. polyamide resin. CONSTITUTION:A hollow molded article consists of a thermoplastic polyester resin, whose main repeating unit is ethylene terephthalate, and contains 1- 100pts.wt. m-xylylene group-contg. polyamide resin such as poly-m-xylyleneadipamide homopolymer or an m-xylylene/p-xylylene adipamide copolymer per 100pts.wt. polyester resin. By incorporating the polyamide resin, the hollow molded article having remarkably improved oxygen gas barrier properties can be obrg. without deteriorating innerent mechanical properties of the thermoplastic polyester resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyester hollow molded article having excellent gas barrier properties. For more details, please refer to J! This invention relates to a hollow molded article having excellent gas barrier properties and comprising a I mixture.

Thermoplastic polyester resin, which is mainly composed of polyethylene terephthalate, has traditionally been used in various containers, films, sheets, etc. due to its excellent mechanical properties, gas barrier properties, chemical resistance, fragrance retention, and hygienic properties. It is processed and 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 food containers whose contents require gas barrier properties. However, it was unsuitable due to its lack of gas barrier properties against oxygen.

The present inventor has conducted extensive research to improve the oxygen barrier properties without impairing the excellent mechanical properties of thermoplastic polyester resin or impairing its practical transparency.
A solution to the problem was found by adding a metaxylylene group-containing polyamide resin, leading to the present invention. That is, the present invention is a hollow molded article made of a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate,
This polyester hollow molded article has excellent gas barrier properties and is characterized by containing 1 to 100 parts by weight of a metaxylylene group-containing polyamide resin per 100 parts by weight of the polyester resin.

In the present invention, the thermoplastic polyester resin containing ethylene terephthalate as the main 7 Th tightening unit usually has an acid component of 80 mol% or more, preferably 90 mol% or more of terephthalic acid, a glycol component of 80 mol%, Preferably, it means a polyester in which 90 mol% or more is ethylene glycol, and the remaining acid components include isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, naphthalene 1,4- or 2,6-dicarboxylic acid, and adipic acid. , sebacic acid, decane 1,10-dicarboxylic acid, hexahyteterephthalic acid, and other glycol components such as propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, Schiftetrahexane dimetatool, 2,2- Examples include polyester resins containing bis(4-hydro-tetraxyphenyl)propane, 2,2-bis(4-hydroxyethoxyphenyl)propane, or p-oxybenzoic acid, p-human-tetraethoxybenzoic acid, etc. as the oxyacid. . Alternatively, a blend of two or more types of polyester may be used so that ethylene terephthalate falls within the above range.

The intrinsic viscosity of the thermoplastic polyester resin of the present invention is 0.5
The value is 5 or more, and 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.

Furthermore, the metaxylylene group-containing polyamide resin used in the present invention is composed of metaxylylene diamine or a mixed xylylene diamine containing metaxylylene diamine and para-xylylene diamine in an amount of 30% or less of the total amount, and a carbon number of 6.
- log α,ω-aliphatic dicarboxylic acid and a polymer containing at least 70 mol % of a structural unit in the molecular chain.

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 varaxylylene himelamito copolymer, metaxylylene/paraxylylene adipamide copolymer, etc., as well as components of these homopolymers or copolymers and fats such as hexamethylene diamine. group diamines, cycloaliphatic diamines such as piperazine, para-bis-
Aromatic diamines such as (2-aminoethyl)benzene, aromatic dicarboxylic acids such as terephthalic acid, lactams such as ε-cab-p-lactam, ω-aminocarboxylic acids such as γ-aminohbutanoic acid, para- Examples include copolymers obtained by copolymerizing aromatic aminocarboxylic acids such as aminomethylbenzoic acid. In the above copolymer, para-xylylene diamine is 3% of the total xylylene diamine.
0% 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 weight.

Meta-xylylene group-containing polyamide resin (hereinafter abbreviated as 8M resin) itself is inherently brittle in an amorphous state, so it is usually necessary that the relative viscosity is 1.15 or more, preferably 2.
．． It is 0 to 4.0.

Since it is a polyester resin, if it is added to a thermoplastic polyester resin, the stretch braking formability will be impaired, and the obtained hollow molded product will be devitrified in a pearl shape and will not function as a transparent container in practical terms. It is also difficult to obtain gas barrier properties.

In addition, when a styrene-acrylonitrile copolymer is added, it has the disadvantage that it cannot be stretched sufficiently at a stretching temperature suitable for polyester resin because its glass transition temperature (T) is high. Since it is a resin and does not induce oriented crystallization even when stretched, it also has the disadvantage that the container deforms due to residual stretching stress.

In contrast to these resins, SM resin itself is originally a crystalline resin, but since it has a relatively high Tg, it is easily amorphized by rapid cooling treatment from a molten state, and thermoplastic polyester resin 10
If added within 100 parts by weight, preferably within 60 parts by weight, of the SM resin per 0 overlapped part, it provides transparency that does not impair practicality, and T9 of the thermoplastic polyester resin.
Since it is almost equal to g, oriented crystallization is sufficiently induced by stretching, and unlike the above-mentioned high gas barrier resin, the excellent mechanical properties of thermoplastic polyester resin are not impaired in any way, and the oxygen gas barrier properties are significantly improved. It becomes a hollow molded body. A particularly preferred amount of BMW fat is 5 to 60 parts by weight per 100 parts by weight of polyester resin.

The gas barrier hollow molded article of the present invention can be obtained by tri-blending a thermoplastic polyester resin with a desired concentration and an 8M resin, and molding the mixture directly with a hollow body molding machine, or with a thermoplastic polyester resin having a desired concentration and an 8M resin. Examples include a method of melt-kneading in an extruder to produce mixed composition pellets, and molding the pellets with a blow molding machine.

It is also possible to use a crusher to crush a layered molded product of thermoplastic polyester resin and 8M resin into a state that can be supplied to a blow molding machine, and then mold it with a blow molding machine. It can be carried out in the same way as blow molding of polyester resin. For example, after producing a parison with a bottomed opening by extrusion swallow molding or injection pro method commonly called direct F-blowing, or by extrusion molding over injection molding using a molding called biaxial stretch blow molding, the parison is stretched using a stretch blowing machine. A blow molding method can be used in which the temperature is adjusted to an appropriate temperature, for example, 70 to 150'C, and stretching in the axial direction with a stretching rod and stretching in the circumferential direction with a compressed gas are carried out simultaneously or sequentially.

By stretching, a hollow molded body can be obtained in which the thin body portion is oriented in at least one direction.The stretching ratio is preferably 2 times or more in area ratio (axial stretching ratio x circumferential stretching ratio), and Even if it is a plastic can that has a lid integrated into a hollow molded product formed by deep drawing after molding, or a cylindrical body obtained by stretching or orienting a pipe formed by extrusion or injection molding from a mixed resin. good.

The hollow molded article according to the present invention may contain colorants, ultraviolet absorbers, antistatic agents, thermal oxidative deterioration inhibitors, antibacterial agents, lubricants, nucleating agents, thermoplastic resins other than those mentioned above, etc., as required. It can be contained within a range that does not cause any damage.

Hereinafter, the present invention will be explained in detail using examples.

The methods for measuring the main characteristics measured in the present invention are shown below.

(1) Intrinsic viscosity (b) of polyester resin: Measured at 30°C using a mixed solvent of phenol/TEF-chloroethane=6/4 (weight ratio).

(2) ηrθ1 of polyamide resin: resin 19 to 96
Heavy N% sulfur i! Relative viscosity measured at 25°C, dissolved in l1100-.

(8) Transparency and haze: Calculated using Hazemeter S manufactured by Toyo Seiki Co., Ltd. according to J-Ko S-6'714 according to the following formula.

Transparency = T2/Tlx 100 (%) Tli incident light amount T2 i Total light transmission amount Tsi Scattered light amount by device T4 i Scattered light amount by device and sample (4) Oxygen transmission 1ti Oxygen transmission amount measuring device 0X-TRAN manufactured by MODIRN 0ONTROLS in the United States l 00 by 1000
The amount of permeation per bottle was measured at 20°C.

(ce/1 container, 24hr -afm) (5)
Tensile properties: Using a tanzak-shaped specimen with a width of IQm, the distance between the chucks was 50 m using Tensilon manufactured by Toyo Baldwin Co., Ltd.
The yield strength and breaking strength and elongation were measured under the conditions of a tensile speed of 50 m/win (23c).

Examples 1 to 5 and Comparative Examples Polyethylene terephthalate (abbreviated as PIT) with (b)=0.72 was used as the polyester/l/resin, and ηrel=2.
2 Polymethaxylylene adipamide (abbreviated as 8M resin)
A bottomed parison with an outer diameter of 25 mm, a length of 130 mm, and a wall thickness of 4 mm was molded using an M + 100 injection molding machine manufactured by Taiki Seisakusho under the molding conditions shown in Table 1.

The open end of this parison was fitted into a parison fitting part equipped with a rotation drive device, and the surface temperature of the parison was raised to 11oC while rotating in an oven equipped with a far-infrared heater.
It was heated until it reached 'c. Thereafter, the parison was transferred into a blow mold and blow molded under the conditions of a drawing rond moving speed of 227 J/sec and a compressed gas pressure of 20 to 9/ad, with a total length of 26
A beer bottle-shaped hollow container with a length of 5 m, an outer diameter of the body of 8°, and an internal volume of 1000° was obtained. Table 2 shows the performance of these containers.
Shown below.

Table 1 The containers obtained in this example have significantly improved oxygen gas barrier properties compared to the conventional polyethylene terephthalate container shown in the comparative example without impairing practical transparency or sacrificing mechanical properties. I understand that. Profit-% u
Itftr Inspector LI-4 vs. 2-sex M4JJL? t
The corner nine is 1%p.

Patent applicant: Toyobo Co., Ltd.

Claims (1)

[Scope of Claims] L A hollow molded article made of a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate, containing 1 to 100 parts by weight of a metaxylylene group-containing polyamide resin per 100 parts by weight of the polyester resin. A polyester hollow molded body with excellent gas barrier properties. 2. A polyester hollow molded article with excellent gas barrier properties as claimed in claim 1, characterized in that the hollow molded article is oriented in at least one direction in the thin body portion.