JP2663578B2 - Polyester hollow molded body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hollow polyester molded article having excellent gas barrier properties and transparency. More specifically, a gas barrier and transparent layer having a layer comprising a mixture of a thermoplastic polyester resin and a meta-xylylene group-containing polyamide resin and a compatibilizer for uniformly and finely dispersing the meta-xylylene group-containing polyamide resin in the thermoplastic polyester resin. The present invention relates to a polyester hollow molded article having excellent properties.

[Conventional technology]

Conventionally, thermoplastic polyester resin mainly composed of polyethylene terephthalate has been focused on its excellent mechanical properties, gas barrier properties, chemical resistance, fragrance retention, transparency, hygiene, safety, etc. It is processed into containers, films, sheets, etc., and is widely used as packaging materials. Particularly, in recent years, the use of hollow containers such as bottles and cans has been remarkable due to improvements in blow molding technology and biaxial stretch blow molding technology.

However, as a biaxially oriented container made of a thermoplastic polyester resin mainly composed of polyethylene terephthalate, it does not necessarily have the perfect performance, and in particular, the content to be filled requires food with a high gas barrier property,
It was unsuitable as a container for medicines and the like because of its lack of gas barrier properties against oxygen.

[Problems to be solved by the invention]

Conventionally, resins having excellent gas barrier properties, such as polyvinyl alcohol (JP-A-54-114572), vinylidene chloride-based resins (JP-A-56-155759), and ethylene have been used to improve the gas barrier properties of plastic containers.・
Containers in which a vinyl alcohol resin (JP-A-56-77143) is laminated or coated 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 or permeated gas stagnation between layers. Further, they have disadvantages such as lack of durability against water resistance and gas barrier property.
Attempts have also been made to obtain a container having excellent gas barrier properties by blending a gas barrier resin and a thermoplastic resin, and as a gas barrier resin, saponified ethylene vinyl acetate copolymer, styrene-acrylonitrile copolymer, It is known that, even in this case, lacks water resistance, impairs stretchability, lacks transparency due to pearl-like devitrification, and has disadvantages such as insufficient gas barrier properties. And no satisfactory results have yet been obtained.

Attempts have also been made to improve gas barrier properties by blending a meta-xylylene group-containing polyamide resin with a thermoplastic polyester resin (Japanese Patent Application Laid-Open No. 52-73966), but transparency is impaired due to poor compatibility. water resistant,
There is a problem that the stretchability is lacking or the barrier properties are significantly reduced during moisture absorption, and the use thereof is limited.

[Means for solving the problem]

The present inventors have conducted intensive studies to solve the above problems, and as a result, without impairing the excellent mechanical properties of the thermoplastic polyester resin at all, and even if blended, the barrier property against oxygen without impairing the transparency. It has been found that a hollow molded body that is improved and whose barrier properties and transparency are not affected by moisture can be obtained by adding a metaxylylene group-containing polyamide resin and a specific copolymerized polyester as a compatibilizer. The invention has been completed. That is,
The present invention provides a hollow molded article comprising a single layer or a multilayer, wherein at least one layer is a thermoplastic polyester (A),
A polyester hollow molded article comprising a mixture of a metaxylylene group-containing polyamide (B) and a modified polyester (C) containing 0.5 to 10 mol% of a copolymer component having a metal sulfonate group.

The thermoplastic polyester as the component (A) of the present invention includes terephthalic acid, isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, naphthalene 1,4- or 2,6-dicarboxylic acid, adipic acid, sebacin as an acid component. Acid, decane 1,10-dicarboxylic acid, hexahydroterephthalic acid,
As glycol components, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, 2,2'-bis (4-hydroxyphenyl) propane, 2,2'-bis (4-hydroxy (Ethoxyphenyl) propane or oxyacid is obtained from p-oxybenzoic acid, p-hydroethoxybenzoic acid, etc., and in the present invention, 80 mol% or more, preferably 90 mol% of the acid component.
The above is terephthalic acid, 80% by mole of glycol component
As described above, a polyester containing ethylene terephthalate in which at least 90 mol% is ethylene glycol as a main repeating unit is preferable.

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

Further, as the metaxylylene group-containing polyamide used as the component (B) used in the present invention, metaxylylenediamine, or a mixed xylylenediamine containing metaxylylenediamine and 30% or less of paraxylylenediamine of the total amount, A polymer containing at least 70 mol% of a structural unit generated from an α, ω-aliphatic dicarboxylic acid having 4 to 10 carbon atoms in a molecular chain is exemplified.

Examples of these polymers include homopolymers such as polymetaxylylene adipamide, polymetaxylylene sebacamide, polymetaxylylene veramide, etc., and metaxylylene / paraxylylene adipamide copolymer, metaxylylene / Copolymers such as para-xylylene pimeramide copolymer, meta-xylylene / para-xylylene azeramide copolymer, and components of these homopolymers or copolymers and aliphatics such as hexamethylenediamine Diamines, alicyclic 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, γ-aminoheptane Ω-aminocarboxylic acids such as acids, and aromatic acids such as para-aminomethylbenzoic acid. Copolymers obtained by copolymerizing Nokarubon acid. In the above copolymer, para-xylylenediamine is based on all xylylenediamine.
It is at most 30%, and the constitutional unit formed from xylylenediamine and aliphatic dicarboxylic acid is at least 70 mol% in the molecular chain.

Since the metaxylylene group-containing polyamide (hereinafter abbreviated as MXD ₆ resin) itself is brittle in the amorphous state, its relative viscosity is usually
It is necessary to be 1.5 or more, preferably 2.0 to 4.0
It is.

The copolymerized polyester of the component (C) in the present invention comprises:
A molded article obtained from the polyester resin composition containing 0.5 to 10 mol% of a copolymer component having a sulfonic acid metal base, having molecular compatibility with a thermoplastic polyester, and finely dispersing an MXD ₆ resin. Is to greatly improve the transparency. Preferably, at least 90 of the structural units
Mole% is ethylene terephthalate, and 0.5 to 10 mol% is a copolymerized polyester which is a copolymer component having a sulfonic acid metal base.

Specifically, the copolymerized polyester is prepared by mixing the raw materials exemplified for the thermoplastic polyester (A) with the following general formula (1)
And a copolymerization component having a metal sulfonate group represented by the formula:

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

M in the general formula representing the metal sulfonic acid compound is sodium, potassium, calcium, parium, lithium,
Magnesium, alkali metals such as strontium, alkaline earth metals, or lead, lanthanum, zinc, etc.,
More preferred metals are sodium, lithium and potassium, and a particularly preferred metal is sodium.

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

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

The molecular compatibility means that the kneaded composition is mixed in a molecular order, and that the glass transition point obtained by DSC or viscoelasticity measurement is substantially one.

The amount of the components (B) and (C) in the component (A) in the present invention varies depending on the type of the component (C).
The component (B) is 1 to 100 parts by weight, preferably 5 to 60 parts by weight with respect to 100 parts by weight, and the mixing ratio of the component (B) to the component (C) is 95: 5 to 5:95, 80:20 to 40:60 is preferred.

If necessary, additives such as an antioxidant, an ultraviolet absorber, an antistatic agent, and a transparent colorant may be added to the mixture.

Next, the method of mixing the components (A) to (C) is not particularly limited, and any method may be used. For example, it can be obtained by mechanically kneading the components with an extruder, a roll mill, a Banbury mixer, or the like. Alternatively, multi-stage kneading may be performed in which the copolymer polyester is kneaded in advance with the MXD ₆ resin, and then the thermoplastic polyester component is kneaded.

Examples of the method for obtaining the gas-barrier hollow molded article of the present invention include a method of dry-blending the above-mentioned components (A) to (C) at a desired concentration and directly molding the same with a hollow-body molding machine, or melt-kneading each component in an extruder. Of the mixed composition pellets, and molding the pellets with a blow molding machine.

The molding by the hollow molding machine can be performed without any difference from the conventional polyester resin hollow molding. For example, extrusion blow molding or injection blow molding, which is generally called direct blow, is a method in which a parison is blow-molded with a compressed gas before it is sufficiently cooled after injection molding, or injection molding or molding in which molding is called biaxial stretch blow molding. After making a parison with a bottomed opening by extrusion molding, the parison is stretched with a stretch blow device at an appropriate temperature, for example, at a temperature of 70 to 150 ° C., and the axial stretching by a stretching rod and the circumferential stretching by a compressed gas are simultaneously or sequentially performed. A method of performing blow molding can be used.

Further, the hollow molded article of the present invention may be composed of multiple layers, at least one of which is the above (A), (B), (C)
What is necessary is just to be comprised from the mixture of.

(Operation)

In the hollow molded article of the present invention, the thermoplastic polyester (A) and the copolymerized polyester (C) have molecular compatibility, and the Tg of each of the components (A), (B) and (C) is substantially the same. Since orientation crystallization by stretching is sufficiently induced,
The excellent mechanical properties of the thermoplastic polyester are not impaired at all, and oxygen gas barrier properties can be significantly improved.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

In addition, the measuring method of the main characteristic measured by this invention is shown below. However, the oxygen permeation amount was in the state of a bottle, and the other items were performed using test pieces cut out from the main body of the bottle.

(1) Intrinsic viscosity [η] of polyester; phenol /
Using a mixed solvent of tetrachloroethane = 6/4 (weight ratio)
Measured at 0 ° C.

(2) ηrel of MXD ₆ resin; 1 g of resin is 100 ml of 96% by weight sulfuric acid
Relative viscosity measured at 25 ° C.

(3) Transparency and haze: Using a haze meter MODEL TC-H III manufactured by Tokyo Denshoku Co., Ltd., it was calculated from the following equation according to JIS-K6741.

Transparency _{= T 2 / T 1 × 100} (%) T ₁ : incident light amount T ₂ : total light transmission amount T ₃ : scattered light amount by the device T ₄ : scattered light amount by the device and the sample (4) Oxygen transmission amount: Oxygen transmission amount measuring instrument OX-TRAM100 manufactured by MODERN CONTROLS, USA It was measured at 20 ° C. as the permeation amount per 1000 cc bottle.

(5) Tensile properties: Using a 10 mm-wide tangled specimen, the distance between the chucks was set to 50 using Tensilon manufactured by Toyo Baldwin Co., Ltd.
The yield strength and the breaking elongation at break were measured under the conditions of mm and a tensile speed of 50 mm / min. (23 ° C.) Examples 1 to 6, Comparative Examples 1 to 3 As a component (C), a copolymer polyester in which 95 mol% of the structural unit was ethylene terephthalate and 5 mol% was 5-sodium sulfoisophthalic acid was used. .

Next, (η) = 0.
Using polyethylene terephthalate (abbreviated as PET) of 80, polymetaxylylene adipamide with ηrel = 2.2 as the MXD ₆ resin as the component (B), and the above-mentioned (C) copolymerized polyester for each component, Pellets were obtained by kneading at the ratios shown in 1 and 2, respectively, and the obtained pellets were used to obtain an outer diameter of 25 m using an M-100 injection molding machine manufactured by each machine.
A bottomed parison m, 130 mm long and 4 mm thick was molded. This parison was fitted with a parison opening end in a parison fitting portion provided with a rotation driving device, and heated while rotating in an oven having a far-infrared heater until the surface temperature of the parison reached 110 ° C. Thereafter, the parison is transferred into the injection mold, and the moving speed of the stretching rod is 22 cm / sec, and the compressed gas pressure is 20 kg / cm.
Blow molding under the conditions of ² , total length 265mm, outer diameter of the body 80mm,
A beer bottle-shaped hollow container having an inner volume of 1000 ml was obtained. Tables 1 and 2 show the performance of these containers.

As is evident from Table 1, the hollow molded article of the present invention has remarkably improved transparency and gas barrier property. It should be noted that the haze value is about 15, and the transparency of the bottle is significantly different in appearance.

As is evident from Table 2, the hollow molded article of the present invention has improved gas barrier properties and a significant decrease in transparency during moisture absorption.

Examples 7 to 10 A molded article was obtained in the same manner as in Example 3 except that the copolymerized polyester of the component (C) used in Example 3 had the composition shown in Table 3. The results are also shown in Table 3.

As is evident from Table 3, when the polyester obtained by copolymerizing 5-sodium sulfoisophthalic acid is used as the component (C), the transparency is improved and the haze is considerably reduced.

[Effects of the Invention] The hollow molded article of the present invention having the above-described structure has excellent transparency, gas barrier properties, and mechanical properties as well as excellent wet and water properties, as demonstrated in Examples. It is very durable as a container that is hardly affected by the minute.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B29L 22:00

Claims (3)

(57) [Claims] In a hollow molded article comprising a single layer or a multilayer, at least one layer contains 0.5 to 10 moles of a copolymer component having a thermoplastic polyester (A), a metaxylylene group-containing polyamide (B) and a metal sulfonate group. % Of a modified polyester (C). 2. The polyester hollow molded article according to claim 1, wherein the main repeating unit of the thermoplastic polyester (A) is ethylene terephthalate. 3. The polyester according to claim 2, wherein at least 90 mol% of the structural units of the modified polyester (C) is ethylene terephthalate and the copolymer component is ethylene isophthalate containing a sulfonic acid metal base. Hollow molded body.