JPH0454702B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyester hollow molded article having excellent gas barrier properties. More specifically, the present invention relates to a hollow molded article having excellent gas barrier properties, which is made of a mixture of a thermoplastic polyester resin and a metaxylylene group-containing polyamide resin. Thermoplastic polyester resins, mainly composed of polyethylene terephthalate, have been used for various containers, films, sheets, etc. due to their 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 as food containers whose contents require gas barrier properties. It was unsuitable due to its lack of gas barrier properties against oxygen. The present inventor has conducted extensive research in order to improve the oxygen barrier properties without impairing the excellent mechanical properties of thermoplastic polyester resins, nor impairing their practical transparency, and has added polyamide resins containing meta-xylylene groups. find a solution to the problem,
This led 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,
Per 100 parts by weight of the polyester resin, 70 to 100 mol% of metaxylylene diamine as an amine component,
Paraxylylene diamine 30 to 0 mol% Polyamide resin 1 containing 70 mol% or more of amide repeating units obtained by reacting an aliphatic dicarboxylic acid having 6 to 10 carbon atoms as an acid component based on the total amide repeating units.
This is a polyester hollow molded article with excellent gas barrier properties, characterized by containing ~100 parts by weight. The thermoplastic polyester resin containing ethylene terephthalate as a main repeating unit as used in the present invention usually has an acid component of 80 mol% or more, preferably 90 mol% or more of terephthalic acid, and a glycol component of 80 mol% or more, preferably 90 mol% or more. It means a polyester in which ethylene glycol accounts for at least mol%, and the remaining acid components include isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, and naphthalene 1,4-
or 2,6-dicarboxylic acid, adipic acid, sebacic acid, decane 1,10-dicarboxylic acid, hexahydroterephthalic acid, and other glycol components such as propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclohexane. Dimethanol, 2,2-bis(4-hydroxyphenyl)propane, 2,2
- bis(4-hydroxyethoxyphenyl)propane or p-oxybenzoic acid as oxyacid,
Examples include polyester resins containing p-hydroxyethoxybenzoic acid and the like. Alternatively, a blend of two or more types of polyester may be used so that ethylene terephthalate falls within the above range. The thermoplastic polyester resin of the present invention has an intrinsic viscosity of 0.55 or more, more preferably 0.65 to 1.4.
It is. 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 polyamide resin used in the present invention is
30% of para-xylylene diamine with metaxylylene diamine or a mixture of metaxylylene diamine and para-xylylene diamine.
% or less, and an α,ω-aliphatic dicarboxylic acid having 6 to 10 carbon atoms (at least one of adipic acid, pimelic acid, corkic acid, azelaic acid, and sebacic acid). It is a polymer containing at least 70 mol% of amide repeating units based on the total amide repeating units. Examples of these polymers include polymethaxylylene adipamide, polymethaxylylene sebacamide,
Homopolymers such as polymethaxylylenesperamide, and metaxylylene/paraxylylene adipamide copolymers, metaxylylene/paraxylylene pimeramide copolymers, metaxylylene/paraxylylene azeramide copolymers, etc. copolymers such as, as well as components of these homopolymers or copolymers with aliphatic diamines such as hexamethylene diamine, cycloaliphatic diamines such as piperazine,
Aromatic diamines such as para-bis-(2-aminoethyl)benzene, aromatic dicarboxylic acids such as terephthalic acid, lactams such as ε-caprolactam, ω-aminocarboxylic acids such as γ-aminoheptanoic acid, Examples include copolymers obtained by copolymerizing aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid. In the above copolymer, paraxylylene diamine accounts for 30% or less of the total xylylene diamine, and the amide repeating unit formed from xylylene diamine and aliphatic dicarboxylic acid is at least 70 moles in the molecular chain. %
That's all. The specific polyamide resin referred to in the present invention Since the polyamide resin (hereinafter abbreviated as SM resin) itself is inherently brittle in an amorphous state, it is necessary that the relative viscosity is usually 1.5 or more, preferably 2.0 to 4.0. Saponified ethylene-vinyl acetate copolymer, which is conventionally known as a gas barrier resin, is itself a crystalline resin, so if it is added to thermoplastic polyester resin, stretch blow moldability will be impaired, and the resulting hollow molded product will be damaged. It devitrifies in a pearl-like form and has no practical function as a transparent container, and it is difficult to obtain the expected gas barrier properties. Furthermore, when a styrene-acrylonitrile copolymer is added, it has a drawback that it cannot be stretched sufficiently at a stretching temperature suitable for polyester resins because its glass transition temperature (Tg) is high. Furthermore, since it is an amorphous 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 because it has a relatively high Tg, it is easily amorphized by rapid cooling treatment from the molten state, and 100 parts by weight of SM resin per 100 parts by weight of thermoplastic polyester resin. If added within 60 parts by weight, it will provide transparency without impairing practicality and also improve its Tg.
Since Tg is almost equal to the Tg of the thermoplastic polyester resin, oriented crystallization is sufficiently induced by stretching, and unlike the above-mentioned high gas barrier resins, the excellent mechanical properties of the thermoplastic polyester resin are not impaired in any way, and the oxygen This results in a hollow molded body with significantly improved gas barrier properties. A particularly preferable amount of SM resin is to maintain transparency within a range that does not impair practicality.
From the point of view of trying to exhibit gas barrier properties as high as possible, the content should be more than 5 parts by weight and 60 parts by weight or less per 100 parts by weight of polyester resin, and in order to have high transparency and also exhibit gas barrier properties. 1 per 100 parts by weight of polyester resin.
~5 parts by weight. As a method for obtaining the gas barrier blow molded article of the present invention, a thermoplastic polyester resin of a desired concentration and
A method of dry blending SM resin and directly molding it with a hollow body molding machine, or a method of melting and kneading a thermoplastic polyester resin of a desired concentration and SM resin in an extruder to form mixed composition pellets, and then molding the pellets with a blow molding machine. A method of molding, etc. are exemplified. It is also possible to use a crusher to crush a layered molded product of thermoplastic polyester resin and SM resin into a state that can be supplied to a blow molder, and then mold the molded product using a blow molder. 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, there are extrusion blow molding, commonly called direct blow molding, and injection blow molding, in which the parison is blown with compressed gas before it has been sufficiently cooled after injection molding, and a molded product called biaxial stretch blow molding. After producing a parison with a bottomed opening by injection molding or extrusion molding, the parison is stretched using a stretch blowing device. The temperature is adjusted to an appropriate temperature, e.g. 70 to 150°C, and the axial direction is stretched by a stretching rod and the circumferential direction is stretched by compressed gas at the same time. Alternatively, a method of successive blow molding can be used. By stretching, a hollow molded body is obtained in which the thin body portion is oriented in at least one direction. The stretching ratio is preferably 2 times or more in terms of area ratio (axial stretching ratio x circumferential stretching ratio), and particularly preferably 3 to 15 times. The wall thickness of the body of the final product is usually 0.1 mm or more, preferably 0.15 mm or more, and particularly preferably 0.2 to 1 mm. In addition, a hollow molded body formed by extrusion molding an unstretched sheet from the above mixed resin and then deep drawing, or a pipe molded from the mixed resin by extrusion or injection molding may be obtained by stretching or orientation. It may also be a plastic can with a lid integrated into the cylinder. 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 necessary. It can be contained within the range. Hereinafter, the present invention will be explained in detail with reference to Examples.
The methods for measuring the main characteristics measured in the present invention are shown below. (1) Intrinsic viscosity of polyester resin [η]; Phenol/tetrachloroethane = 6/4 (weight ratio)
Measurement was performed at 30°C using a mixed solvent. (2) ηrel of polyamide resin; 1g of resin is 96% by weight
Relative viscosity measured at 25°C, dissolved in 100ml of sulfuric acid. (3) Transparency and haze: Calculated using Hazemeter S manufactured by Toyo Seiki Co., Ltd. according to the following formula according to JIS-K6714. Transparency = T ₂ / T ₁ × 100 (%) Haze = T ₄ - _{T 3} (T ₂ / T ₁ ) / T ₂ × 100 (%) T ₁ ; Incident light amount T ₂ ; Total light transmission amount T ₃ ; Equipment Amount of light scattered by T ₄ : Amount of light scattered by the device and sample (4) Amount of oxygen permeation; US MODERN CONTROLS
Using the company's oxygen permeation measuring device OX-TRAN100,
The amount of permeation per 1000 c.c. bottle was measured at 20°C. (cc/1 container, 24 hr, afm) (5) Tensile properties: Using a strip-shaped specimen with a width of 10 mm, it was measured using a tensilon manufactured by Toyo Baldwin Co., Ltd., under the conditions of a chuck distance of 50 mm and a tensile speed of 50 mm/min. Yield strength and breaking strength and elongation were measured (23°C). Examples 1 to 5 and Comparative Examples Using polyethylene terephthalate (abbreviated as PET) with [η] = 0.72 as the polyester resin,
ηrel as metaxylylene group-containing polyamide resin
Using polymethaxylylene adipamide (abbreviated as SM resin) of = 2.2, a bottomed parison with an outer diameter of 25 mm, a length of 130 mm, and a wall thickness of 4 mm was made using an M-100 injection molding machine made by Meiki Seisakusho. It was molded under the molding conditions shown below. The open end of this parison was fitted into a parison fitting part equipped with a rotation drive device, and heated while rotating in an oven equipped with a far-infrared heater until the surface temperature of the parison reached 110°C. After that, the parison was transferred into a blow mold and blow molded under the conditions of a stretching rod moving speed of 22 cm/sec and a compressed gas pressure of 20 Kg/cm ² to produce a beer with a total length of 265 mm, an outer diameter of the body of 80 mm, and an internal volume of 1000 ml. A bottle-shaped hollow container was obtained.
Table 2 shows the performance of these containers.

[Table] Example 6 Using 3 parts by weight of SM resin for 100 parts by weight of PET described in Example 1, a beer bottle-shaped hollow molded product having an internal volume of 1000 ml was molded according to the molding method described in Example 1. The tensile strength of this hollow molded body is 1100
Kg/ ^cm2 , transparency 83%, haze 15%, enzyme permeation amount is
It was 0.38cc/book, 24hr, ATM.

[Table] Compared to the conventional polyethylene terephthalate container shown in the comparative example, the container obtained in this example does not impair practical transparency, does not sacrifice any mechanical properties, and has significantly improved oxygen gas barrier properties. I understand that. The resulting container may optionally be further provided with a water-resistant and scratch-resistant coating.

Claims (1)

[Scope of Claims] 1. A hollow molded article made of a thermoplastic polyester resin whose main repeating unit is ethylene terephthalate, which contains 70 parts of metaxylylene diamine as an amine component per 100 parts by weight of the polyester resin.
~100 mol%, paraxylylenediamine 30-0 mol%, contains at least 70 mol% or more of amide repeating units obtained by reacting an aliphatic dicarboxylic acid having 6 to 10 carbon atoms as an acid component based on the total amide repeating units. A polyester hollow molded article having excellent gas barrier properties, characterized in that it contains 1 to 100 parts by weight of a polyamide resin. 2. The polyester hollow molded article having excellent gas barrier properties as claimed in claim 1, wherein the hollow molded article is oriented in at least one direction in the thin body portion.