JPH03193325A - Polyester hollow molded body whose color tone is improved - Google Patents

Abstract

PURPOSE:To prevent yellowing by improving oxygen gas barrier properties without spoiling dynamical properties, by a method wherein at least one layer should be a matter where specific quantities of a methaxylylene group and specific modified copolymerization polyester and a cobalt chemical compound as metallic cobalt to the whole composition are contained into specific thermoplastic polyester. CONSTITUTION:Thermoplastic polyester of an ingredient A should be a polyester consisting mainly of ethylene terephthalate as a repeating unit and an ingredient B should be a polyamide containing a methaxylene group, in at least one layer of a hollow molded body. Modified copolymerization polyester of an ingredient C is obtained by grafting unsaturated carboxylic acid or its derivative to the copolymerization polyester having at least one kind of a chemical compound selected out of aliphatic dicarboxylic acid or cyclohexane dimethanol or hydrogenated terephthalic acid for its one ingredient. Compounding quantities of those ingredients should be respectively that the ingredient B is 1-100pts.wt. and a mixture ratio between the ingredients B, C is 95:5-5:95 on the basis of 100pts.wt. ingredient A. Then a cobalt chemical compound of an ingredient D is contained 10-1,000ppm as metallic cobalt to the whole composition.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Applications) The present invention relates to a polyester hollow molded article having excellent gas barrier properties and transparency, and improved color tone. More specifically, it is a polyester hollow molded product with excellent gas barrier properties and transparency, and improved color tone, which is made by blending a thermoplastic polyester resin and a metaxylylene group-containing polyamide resin with a compatibilizer and a cobalt compound that bind the two components together. It is related to.

(Conventional technology) Thermoplastic polyester resin, which mainly consists of polyethylene terephthalate, has long been known for its excellent mechanical properties, gas barrier properties, chemical resistance, fragrance retention, transparency, hygiene, safety, etc. It has attracted attention and is processed into various containers, films, sheets, etc., and is widely used as packaging material. In particular, in recent years, advances in blow molding technology, especially two-wheel 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.

(Problems to be Solved by the Invention) Conventionally, in order to improve the gas barrier properties of plastic containers, resins with excellent gas barrier properties, such as polyvinyl alcohol (Japanese Unexamined Patent Publication No. 114572/1982), vinylidene chloride resins (Japanese Patent Laid-Open No. 114572/1983), and (Japanese Patent Application Laid-open No. 56-155759), ethylene vinyl alcohol resin (Japanese Patent Application Laid-open No. 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, attempts were made to improve gas barrier properties by blending meta-xylylene group-containing polyamide resin with thermal 11J plastic polyester resin (Japanese Patent Laid-Open Nos. 58-90033 and 58-16).
No. 0344), but it has problems such as poor compatibility, which impairs transparency, lacks water resistance and stretchability, and significantly reduces barrier properties when moisture is absorbed. .

In order to improve the poor mutuality, the present inventors proposed a specific mutualization method in JP-A No. 83-213529. This method is certainly used in JP-A-58-90033 and JP-A-58-
Compared to the composition of the simple blend of No. 160344, the effect of increasing the transparency to 11] was recognized, but unfortunately it had the disadvantage of being colored yellow or brown by the compatibilizer. Depending on the content, there may be restrictions on usage due to color tone.

(Means for Solving the Problems) As a result of intensive research by the present inventors to solve the above problems,
It does not impair the excellent mechanical properties of thermoplastic polyester resin, and even when blended, it improves its barrier properties against oxygen without impairing its transparency or color tone, and its barrier properties and transparency are resistant to the effects of moisture. It has been discovered that a hollow molded body that does not absorb heat can be obtained by adding a metaxylylene group-containing polyamide resin and a specific modified copolymerized polyester as a compatibilizer, and has finally completed the present invention.

That is, the present invention provides a hollow molded article consisting of a single layer or multiple layers, in which at least one layer is made of thermoplastic polyester (A) whose main repeating unit is ethylene terephthalate.
To the copolymerized polyester containing metaxylylene group-containing polyamide (B) and at least one component selected from aliphatic dicarboxylic acids, cyclohexanedimethanol, and hydrogenated terephthalic acid, unsaturated carboxylic acids or their Modified copolymerized polyester grafted with a derivative (C
) and a cobalt compound (D) in an amount of 10 to 1,000 ppm as metallic cobalt based on the total composition.

The thermoplastic polyester that is component (A) of the present invention is:
Acid components include terephthalic acid, isophthalic acid, diphenyl ether 4,4'-dicarboxylic acid, naphthalene 1,4-
Or 2,6-dicarboxylic acid, adipic acid, sebacic acid, decane 1,10-dicarboxylic acid, hexahydroterephthalic acid, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, cyclohexane as a glycol component Obtained from dimethanol, 2,2'-bis(4-hydroxyphenyl)propane, 2,2'-bis(4-hydroxyethoxyphenyl)propane or oxyacid from p-oxybenzoic acid, p-hydroethoxybenzoic acid, etc. In the present invention, 80 mol% or more of the acid component is dicaterephthalic acid, preferably 90 mol% or more, and 80 mol% or more, preferably 90 mol% or more of the glycol component is ethylene glycol. Repeat over ethylene terephthalate! Polyester with the 11th position is preferred.

The thermoplastic polyester of the present invention has an intrinsic viscosity of 0.55 or more, preferably 0.65 to 1.4. If the intrinsic viscosity is 0.55 and is not soaked, 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 as component (B) used in the present invention is metaxylylene diamine or a mixed xylylene diamine containing metaxylylene diamine and 30% or less of para-xylylene diamine of 11i, and carbon Examples include polymers containing at least 70 mol % of structural units formed from 4 to 10 α,ω-aliphatic dicarboxylic acids in the molecular chain.

Examples of these polymers include homopolymers such as polymethaxylylene adipamide, polymethaxylylene adipamide, polymethaxylylene adipamide, polymethaxylylene adipamide, etc., and metaxylylene/paraxylylene adipamide copolymers, metaxylylene 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 polymerized copolymers. In the above copolymer, para-xylylene diamine accounts for 30% of the total xylylene diamine.
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 referred to as MXD, abbreviated as 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 modified copolymerized polyester of the component (C) in the present invention has molecular compatibility with the thermoplastic polyester, finely disperses the MXD resin, and significantly improves the transparency of the molded product obtained from the polyester resin composition. It is something that makes you

Specifically, terephthalic acid accounts for 60 mol% or more of the acid component, preferably 70 mol% or more, and 3% of the glycol component
0 mol% or more, preferably 50 mol% or more of carbon atoms
12, preferably 2-4 alkylene glycol, containing as one component at least one compound selected from aliphatic dicarboxylic acids such as sebacic acid, adipic acid, dodecanedioic acid, cyclohexanedimethanol or hydrogenated terephthalic acid. It is obtained by grafting an unsaturated carboxylic acid or a derivative thereof onto a copolymerized polyester.

The aliphatic dicarboxylic acid which is the copolymerization component is preferably 5 to 50 mol%, particularly 10 to 30 mol%, based on the total acid components, and in the case of hydrogenated terephthalic acid, it is 5 to 60 mol% based on the total acid components. The amount of cyclohexanedimethanol is preferably 5 to 70 mol%, especially 20 to 50 mol% based on the total glycol component. The intrinsic viscosity of the obtained copolymerized polyester is preferably 0.40 or more, more preferably 0.50 to 1.4.

Examples of unsaturated carboxylic acids or derivatives thereof to be grafted onto the copolymerized polyester include maleic acid, maleic anhydride, fumaric acid, itaconic acid, acrylic acid, crotonic acid, and their anhydrides.

Examples of cobalt compounds include inorganic cobalt compounds such as oxides, halides, sulfates, nitrates, carbonates, and phosphates, and organic cobalt complexes such as carboxylic acid cobalt salts having 2 to 20 carbon atoms and cobalt acetylacetonate. It will be done.

In the case of cobalt salts of aliphatic carboxylic acids, cobalt salts of saturated fatty acids that do not have double bonds in their alkyl groups are preferred.

(B) for component (A) in the present invention.

The blending amounts of components (C) and (D) vary slightly depending on the type of component (C), but the amount of component B) is 1 to 100 parts by weight per 100 parts by weight of component (A). If component (B) is less than 1 part positive, the gas barrier properties will be poorly expressed, and if it exceeds 100 parts positive, transparency will decrease. Preferably 1-50
It is a heavy masticator.

The mixing ratio of component (B) and component (C) is 95:5 to 5:9
5, particularly 70:30 to 40:80.

In addition, the amount of component (D) is preferably increased or decreased depending on the amount of component (C), but the amount of cobalt metal in the entire composition is 10%.
It is sufficient if the content is ~1000 pp■, preferably 2
0 to 500 ppm. If it is less than 10 pp-, yellowing cannot be prevented, and if it exceeds 11,000 pp, the crystallization rate of the polyester becomes faster, making it difficult to obtain a transparent molded product.

Next, as a method for mixing the components (A) to (D),
It is not particularly limited and may be carried out by any method. For example, each component is triblended just before molding,
The hollow precursor molded body may be molded using an injection molding machine or an extrusion molding machine, or may be mechanically kneaded using a roll mill, a Banbury mixer, or the like. Alternatively, multi-stage kneading may be used in which the MXD, resin, modified copolyester, and cobalt compound are kneaded in advance, and then the thermoplastic polyester component is kneaded.

Furthermore, for cobalt compounds, polyester and/or
Alternatively, it may be added at any stage during the polymerization of the modified copolymerized polyester or during the polymerization of MXD8.

The present invention also includes antioxidants, ultraviolet absorbers,
Additives such as antistatic agents and transparent colorants can be added.

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, in extrusion blow molding, which is generally called direct blow molding, or injection blow molding, the parison is blow molded with compressed gas before it has been sufficiently cooled after injection 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 with a stretching rod and circumferential stretching with compressed gas are performed simultaneously or sequentially. A blow molding method can be used.

(Function) The hollow molded article of the present invention comprises (A) thermoplastic polyester and (C
) Since the modified copolymerized polyester has molecular compatibility and the Tg of each component (A), (B), and (C) is approximately equal, oriented crystallization by stretching is sufficiently induced. The excellent mechanical properties of thermoplastic polyester are not impaired in any way, and the oxygen gas barrier properties are significantly improved. At the same time, yellowing is prevented by the addition of cobalt compound (D). A container is obtained.

(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 [η] of polyester: Measured at 30°C using a mixed solvent of phenol/tetrachloroethane=6/4 (weight ratio).

(2) MXD, ηrel of resin; 96% by weight of 1 g of resin
Relative viscosity measured at 25°C, dissolved in 100 mQ of sulfuric acid.

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

Transparency = 72/T, xl 00 (%)゛1゛2 Tl Two-person irradiation amount T2: Total light transmission amount T, J: Scattered light amount by the device T4: Scattered light amount by the device and sample (2) Yellowing color b Value (abbreviated as Co-b) was measured using a color difference meter 101-DP manufactured by Nippon Denshoku Industries Co., Ltd.

■ Oxygen permeation rate; US MODERN C0NTR0LS
10 by oxygen permeation measurement device 0X-TRANloo manufactured by Manufacturer.
The amount of permeation per 00cc bottle was measured at 20°C.

(6) Tensile properties; width 10. ．． Yield strength and breaking strength and elongation were measured using a tanzaku-shaped test piece using a Tensilon manufactured by Toyo Baldwin Co., Ltd. under conditions of a chuck distance of 50 cm-1 and a tensile rate of 50 cm/win. (23°C) Example 1.2 Comparative Example 1.2.3 Copolymerized polyester (terephthalic acid/
Ethylene glycol/cyclohexanedimethanol = 1
00/65/35) 0.0% maleic anhydride per 100 parts by weight.
5 parts by weight of Tsukumir peroxide and 0.2 parts by weight of Tsukumir peroxide were mixed, melt-kneaded in a 30 mm diameter twin-screw extruder at 240°C under a nitrogen atmosphere, extruded, cooled, and pelletized to obtain a graft of maleic anhydride. A modified copolyester having a ratio of 1.5 mol % was obtained.

Next, as the polyester which is the component (A), [η]=O,
SO polyethylene terephthalate (abbreviated as PET) 8
0 parts by weight, MXD as component (B), and ηre as resin.
10 parts by weight of polymethaxylylene adipamide of l = 2.2 and 10 m acid parts of the modified copolymerized polyester (C), (
Cobalt acetate was blended with a total of 100 parts by weight of A) + (B) + (C) in the proportions shown in Table 1, and melt-kneaded using an extruder to obtain pellets. The obtained pellets were each dried in a vacuum dryer at 120°C for 16 hours, and then dried with M manufactured by Meiki Seisakusho.
-100 type injection molding machine with outer diameter of 25mm and length of 1
A bottomed parison with a thickness of 30 mm and a wall thickness of 4 mw+ was molded.

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 100° while rotating in an open space equipped with a far-infrared heater.
It was heated to ℃. Thereafter, 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, with a total length of 285 mm.
,.

A beer bottle-shaped hollow container with a body having an outer diameter of 80 mm and an internal volume of 1000 mQ was obtained. The performance of these containers is shown in Table 1.

Table 1 Terephthalic acid/adipic acid I ethylene glycol = 80/20//1 as the copolymerized polyester of Example 1
A molded article was obtained in the same manner except that a molded article having a molar composition of 0.00 was used. The results are shown in Table 2.

Table 2 As is clear from Table 1, the yellowing degree of the hollow molded article of the present invention is significantly improved, and at the same time, the amount of oxygen permeation is also reduced.

Example 3.4 Comparative Example 4.5.6 As is clear from Table 2, the hollow molded article according to the composition of the present invention has an extremely low degree of yellowing and has improved gas/<IJ properties.

Example 5.6 Comparative Example 7.8.9 As the copolymerized polyester of Example 1, terephthalic acid/hydrogenated terephthalate I ethylene glycol = 80/20
// A molded article was obtained in the same manner except that one having a 100 mol composition was used. The results are shown in Table 3.

Table 3: 10 parts by weight of adipamide, 20 parts by weight of the above modified copolymerized polyester as component (C), and cobalt acetate as component (D) in terms of cobalt metal, based on the total amount of (A) + (B) + (C). Add the amount to make ppm,
After drying in a vacuum dryer at 120° C. for 16 hours, a hollow container of 1 OOOmQ was obtained in the same manner as in Example 1. Table 4 shows the evaluation results of Comparative Example 10, which was made into a hollow molded product in the same manner as one with a composition that does not contain component (D).
Shown below.

Table 4 As is clear from Table 3, even when hydrogenated terephthalic acid copolyester is used, the hollow molded article according to the composition of the present invention has
Significant improvements in yellowing degree and gas barrier properties were observed.

Example 7 Comparative Example 10 After obtaining the modified copolyester (C) component in the same manner as in Example 1, 80 parts by weight of PET as the (A) component and (B
) As is clear from Table 4, the yellowing degree and gas barrier properties are significantly improved even by the triblend method before molding.

(Effect of the invention) By adding the compatibilizer (C) component according to the present invention, the dispersibility of the thermoplastic polyester (A) component and the metaxylylene group-containing polyamide (B) component is improved, and the transparency of the molded product is improved. The invention is characterized in that yellowing and coloring due to addition of component (C) is prevented by addition of a cobalt compound (component D), thereby obtaining a transparent molded product in which coloration is prevented.

Claims (1)

[Claims] In a blow molded article consisting of a single layer or multiple layers, at least one layer contains a thermoplastic polyester (A) whose main repeating unit is ethylene terephthalate, a metaxylylene group-containing polyamide (B), an aliphatic dicarboxylic acid, cyclohexanedimethanol, and water. A modified copolyester (C) obtained by grafting an unsaturated carboxylic acid or a derivative thereof to a copolyester containing at least one selected from terephthalic acid as one component and a cobalt compound (D) are added to the entire composition. 10-100 as metal cobalt
A polyester hollow molded article with improved color tone, characterized in that it contains 0 ppm.