JPH11209592A - Resin composition, molded product and bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molded product, especially a bottle, having excellent transparency, a low acetaldehyde content and a low oligomer content. SOLUTION: This resin composition comprises (A) a thermoplastic polyester containing ethylene terephthalate units as main repeating units and (B) a thermoplastic polyester containing ethylene naphthalenedicarboxylate units as main repeating units in a blend weight ratio of 44/56 to 98/2. Therein, the contents of Ge and Sb contained in the resin composition are 20-90 ppm and 3-110 ppm, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection-molded article or bottle comprising a thermoplastic polyester resin composition, which is excellent in transparency and has a small amount of acetaldehyde and oligomers, and a fat composition used for molding the bottle.

[0002]

2. Description of the Related Art Conventionally, seasonings, oils, soft drinks, beer,
Glass has been widely used as a material for containers such as sake, cosmetics and detergents. However, glass has drawbacks such as heavy weight, high logistics cost, and easy breakage and danger.

[0003] The conversion from glass containers to plastic containers is rapidly progressing in an attempt to overcome these disadvantages of glass containers. Among these plastic materials, polyethylene terephthalate is excellent in mechanical strength, heat resistance, transparency, gas barrier properties and the like, and has been widely used as a substitute material for glass containers.

However, the polyethylene terephthalate container has insufficient ultraviolet ray blocking ability depending on the application, so that the irradiation of ultraviolet rays from the outside deteriorates the content of the food and deteriorates the taste, and the cosmetics fade and deteriorate to lower the commercial value. There is a problem. In addition, polyethylene terephthalate itself is a resin with low heat resistance unless crystallized, and depending on the type of content, it is necessary to shower hot water after filling or hot water for sterilization, and a material with high heat resistance is required. I have. Further, depending on the contents, higher gas barrier properties are required to extend the shelf life.

[0005] In recent years, it has been known that such problems can be solved by blending polyethylene naphthalene dicarboxylate with polyethylene terephthalate.

However, when a resin is produced by a conventionally known copolymerization method, it is necessary to lower the solid-state polymerization temperature due to a lowering of the melting point, thereby lowering the productivity. It is necessary to manufacture a resin in which the mixing ratio is changed for each quality, resulting in an increase in manufacturing cost and complicated management in molding. Further, since the resin itself becomes amorphous when the copolymerization amount is in the range of 20 to 80 mol%, the handling properties such as drying and solid-phase polymerization are deteriorated, or the desired physical properties are not obtained.

For this reason, a method of blending polyethylene naphthalene dicarboxylate with polyethylene terephthalate and molding has been proposed as a method capable of flexibly coping with the required quality and as a method of reducing the production cost of resin and molded articles.

[0008]

However, the polyethylene terephthalate and the polyethylene naphthalenedicarboxylate are inferior in compatibility and the molded product obtained by simply blending the two is cloudy and has low transparency, so that the value as a commercial product is low. Is significantly impaired. Even if it is possible to select a severe molding condition such as raising the injection temperature or increasing the back pressure to increase the compatibility and obtain a transparent molded product, a large amount of acetaldehyde or oligomer is generated during molding, The oligomer adheres to the vent portion of the mold of the injection molding machine and causes problems such as burns and short shots. In particular, if the amount of acetaldehyde is large in beverages and the like, the flavor of the contents is impaired.

Since acetaldehyde and oligomers are generated in large amounts during molding, the problem cannot be solved simply by reducing the amount of acetaldehyde or oligomer in the polymer used.

An object of the present invention is to provide a molded article having excellent transparency and containing a small amount of acetaldehyde and a small amount of oligomers
Especially in providing bottles.

[0011]

Means for Solving the Problems The present inventor has focused on such problems and has identified a specific thermoplastic polyester whose main repeating unit is ethylene terephthalate and a specific thermoplastic polyester whose main repeating unit is ethylene naphthalene dicarboxylate. It has been found that by using a resin composition in which polyester is blended in a specific range, molded articles and bottles having good transparency and having a small amount of acetaldehyde and oligomers can be obtained, thereby completing the present invention.

That is, the present invention provides a thermoplastic polyester (A) whose main repeating unit is ethylene terephthalate and a thermoplastic polyester (B) whose main repeating unit is ethylene naphthalene dicarboxylate in a weight ratio of 44 to 98:56. 2 is a resin composition obtained by blending, wherein Ge contained in the resin composition is 20 to
The resin composition has 90 ppm and Sb of 3 to 110 ppm.

In the present invention, the thermoplastic polyester (A) in which the main repeating unit is ethylene terephthalate is mainly intended for a homopolymer of ethylene terephthalate, but a part of the terephthalic acid component is, for example, isophthalic acid or naphthalenedicarboxylic acid. Other aromatic dicarboxylic acids such as diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, tetrahydronaphthalenedicarboxylic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, decahydronaphthalenedicarboxylic acid, etc. Aliphatic dicarboxylic acids such as alicyclic dicarboxylic acid, adipic acid, sebacic acid, azelaic acid, etc., p-β-hydroxyethoxybenzoic acid, ε-oxycaproic acid, etc. Substituted with one or more other difunctional carboxylic acids such as
It may be a copolymer copolymerized in a range of not more than wt%.

A part of the diol component is, for example, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentyl glycol, diethylene glycol, 1,1-
One of other polyfunctional compounds such as cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2-bis (4′-β-hydroxyphenyl) propane, and bis (4′-β-hydroxyethoxyphenyl) sulfonic acid It may be a copolymer substituted by more than one kind and copolymerized in a range of 10% by weight or less of the entire polyester.

In the present invention, the thermoplastic polyester (A) in which the main repeating unit is ethylene terephthalate is obtained by copolymerizing a dicarboxylic acid component and a diol component with each other in an amount of 10% by weight or less of the total polyester. Is also good.

In the present invention, the thermoplastic polyester (B) in which the main repeating unit is ethylene naphthalenedicarboxylate is mainly a homopolymer of polyethylene-2,6-naphthalenedicarboxylate. Part of the naphthalenedicarboxylic acid component,
2,7-, 1,5-, 1,7- and other isomers of naphthalenedicarboxylic acid, terephthalic acid, and one or more of the aforementioned polyfunctional carboxylic acids,
It may be a copolymer copolymerized in a range of 0% by weight or less.

Further, a copolymer in which a part of the diol component is copolymerized with one or more of the above-mentioned polyfunctional glycols in a range of 20% by weight or less of the total polyester may be used.

In the present invention, the thermoplastic polyester (B) in which the main repeating unit is ethylene naphthalenedicarboxylate has a dicarboxylic acid component and a diol component each containing 20 wt% of the total polyester.
It may be copolymerized in the following range.

The thermoplastic polyesters (A) and (B) used in the present invention may optionally contain an antioxidant,
The thermoplastic polyester (A) used in the present invention may be one to which an ultraviolet absorber, a plasticizer, or the like is added, or may be one that has been subjected to treatment such as hot water treatment or humidity control treatment after polymer production. Any of (B) can be produced by a conventionally known method, but at least the thermoplastic polyester whose main repeating unit is ethylene terephthalate can reduce the amount of acetaldehyde in the resin to 1 by solid phase polymerization.
It is preferably at most 0 ppm, more preferably at most 2 ppm.

The present invention is characterized in that the content of the metal originating from the polymerization catalyst in each thermoplastic polyester satisfies specific conditions.

[0021] The present invention relates to a method for preparing Ge contained in a resin composition.
Should be 20 to 90 ppm and Sb should be 3 to 110 ppm. If the Ge content is less than 20 ppm, the polymerization rate during the production of the polymer becomes extremely slow, which is not preferable. If the Ge content exceeds 90 ppm, the effect of reducing the amount of acetaldehyde after molding is not sufficient, which is not preferable. On the other hand, if the Sb content is less than 3 ppm, the polymerization rate in producing the polymer becomes extremely slow, which is not preferable. If the Sb content exceeds 110 ppm, the effect of reducing the acetaldehyde amount and the oligomer amount after molding is not sufficient, which is not preferable. .

Ge used as a polymerization catalyst includes:
For example, compounds such as germanium dioxide and germanium tetrabutoxide can be exemplified. Examples of Sb used as a polymerization catalyst include antimony trioxide and antimony acetate.

Ge and Sb can be derived from both a thermoplastic polyester whose main repeating unit is ethylene terephthalate and a thermoplastic polyester (B) whose main repeating unit is ethylene naphthalenedicarboxylate.

Ge is preferably derived from a polymerization catalyst used for producing a thermoplastic polyester whose main repeating unit is ethylene terephthalate.
Is preferably derived from a polymerization catalyst used for producing a thermoplastic polyester whose main repeating unit is ethylene naphthalenedicarboxylate.

In the present invention, the thermoplastic polyester whose main repeating unit is ethylene terephthalate is
It is preferable to contain Ge in an amount of 30 ppm or more and 100 ppm or less. If the Ge content is less than 30 ppm, the polymerization rate in producing the polymer will be significantly reduced, while
If the content exceeds 100 ppm, the effect of reducing the amount of acetaldehyde after molding is not sufficient. The Ge content is more preferably 40 ppm or more and 90 ppm or less, particularly preferably 50 ppm or more and 80 ppm or less.

The thermoplastic polyester having a main repeating unit of ethylene naphthalenedicarboxylate preferably contains Sb in an amount of 100 ppm or more and 350 ppm or less. If the amount is less than 100 ppm, the polymerization rate during the production of the polymer becomes extremely slow, and if it exceeds 350 ppm, the effect of reducing the amount of acetaldehyde and oligomer after molding is not sufficient.

In the present invention, the blend ratio of the thermoplastic polyester preferably satisfies a specific condition. That is, a thermoplastic polyester (A) in which the main repeating unit containing Ge is 30 ppm or more and 100 ppm or less is ethylene terephthalate and a thermoplastic polyester (B) in which the main repeating unit containing Sb is 100 ppm or more and 350 ppm or less is ethylene naphthalenedicarboxylate Is (A) :( B) = 44-9 by weight ratio
8:56 to 2 are preferred.

When the blending ratio of the thermoplastic polyester (A) whose main repeating unit is ethylene terephthalate to the whole of the blend exceeds 98 wt%, when the molded article is formed, the intended effect of improving ultraviolet ray blocking performance and gas barrier properties, heat resistance, If the effect is not sufficient, the effect of reducing the amount of acetaldehyde and oligomers is not sufficient.

Examples of the molded article of the present invention include a preform obtained by an injection molding method. It is necessary to set appropriate molding conditions for the molding temperature so that the molded product is transparent.However, as long as a transparent molded product can be obtained, the molding temperature should be set as low as possible and the residence time should be set as short as possible. desirable.

In injection molding, the molding machine cylinder extends from a position where the resin is subjected to heat shearing treatment in the cylinder to a substantially molten state to a position immediately before the molten resin is accumulated on the cylinder tip in the measuring step. It is preferable that the air be exhausted through at least one vent port provided in the apparatus and that the inside of the molding machine be depressurized to perform molding, so that acetaldehyde and oligomers can be further reduced to a lower level.

The bottle of the present invention can be obtained by blow molding a preform molded as described above by a known method. The molded preform may be cooled once and then reheated before being blown, or may be blown as it is without cooling after the preform is formed.

Thus, the molded articles and bottles produced by the above-described method are excellent in transparency while having the ultraviolet ray blocking ability, gas barrier property, and heat resistance improving effect of polyethylene naphthalenedicarboxylate, and the content of acetaldehyde and oligomer contained therein Therefore, it can be applied not only to conventional use of polyethylene terephthalate but also to use requiring higher quality.

[0033]

The present invention will be described below in detail with reference to examples. The main measurement conditions for the physical properties are as follows.

(1) Haze Measured by a turbidity meter manufactured by Nippon Denshoku Industries Co., Ltd.

(2) Acetaldehyde content The sample was frozen and pulverized in liquid nitrogen and then measured by gas chromatography.

(3) Amount of acetaldehyde (hereinafter referred to as HS-AA) by a head space method A bottle obtained by blow molding is left at room temperature for 20 minutes, and then 2k
The mixture was purged with gf / cm ² of nitrogen for 30 seconds and sealed with an aluminum cap. After holding at 22 ° C. for 24 hours, the amount of acetaldehyde contained in the gas phase in the bottle was measured by gas chromatography.

(4) Amount of oligomer The sample was pulverized at room temperature, dissolved in a mixed solvent of hexafluoroisopropanol: chloroform = 1: 1, and the solution was measured by GPC. Regarding the amount of oligomer, the total amount of oligomers of pentamer or less was calculated from a calibration curve prepared in advance for those composed of ethylene terephthalate units, those composed of naphthalenedicarboxylate units, and those containing both units.

Example 1 Polyethylene terephthalate pellets having a Ge content of 70 ppm (IV (measured using a mixed solvent of tetrachloroethane: phenol = 4: 6))
= 0.76, acetaldehyde content = 1.0 ppm, oligomer content = 0.38 wt%) 90 wt% and Sb content 2
00 ppm polyethylene naphthalenedicarboxylate pellets (IV (measured in the same manner as above)) = 0.46, acetaldehyde amount = 151 ppm, oligomer amount = 0.
After dry blending 10 wt% of the mixture and drying with hot air at 160 ° C. for 5 hours, an injection molding machine (M100 manufactured by Meiki Co., Ltd.) was used.
-DM), injection molding was performed in a mold cooled with a cylinder set temperature of 305 ° C, a molding cycle of 90 seconds, and cooling water of 10 ° C to obtain a preform weighing 55 g. This preform has an outer diameter of a cylindrical body of 22 to 24 mm and a thickness of 3.5 m.
m, one end of a total length of 150 mm is bottomed,
It was a substantially amorphous, colorless and transparent molded product. The amount of acetaldehyde in the obtained preform was 29 ppm, and the amount of oligomer was 0.46 wt%. The preform was blow-molded into a 1.5 L bottom petaloid free-standing bottle using a RHB-L blow molding machine manufactured by Cincinnati Milacron. The haze of the body of the obtained bottle was 1.4%.

[Examples 2 to 3] A preform and a bottle were molded in the same manner as in Example 1 except that the blend ratio of polyethylene terephthalate and polyethylene naphthalenedicarboxylate and the type of polyethylene naphthalenedicarboxylate were changed. Physical properties were measured. Table 1 shows the results.

[Examples 4 and 5] 1 from the nozzle of the injection molding machine
00 mm hopper side (this position is in the section from the position where the resin undergoes heat shearing treatment in the cylinder and becomes substantially molten state to the position immediately before the molten resin is accumulated at the tip of the cylinder in the measuring step) A preform and a bottle were obtained by the same raw materials and method as in Example 1 except that a vent port was provided, and the pressure was reduced to 5 mmHg by a vacuum pump and injection molding was performed. Table 1 shows the results.

Comparative Examples 1 to 6 Preforms and bottles were formed in the same manner as in Example 1 except that the blend ratio of polyethylene terephthalate and polyethylene naphthalenedicarboxylate and the type of polyethylene naphthalenedicarboxylate were changed. Physical properties were measured. Table 1 shows the results.

[0042]

[Table 1]

[0043]

Industrial Applicability According to the present invention, a thermoplastic polyester having a main repeating unit of ethylene terephthalate and a thermoplastic polyester having a main repeating unit of ethylene naphthalene dicarboxylate are excellent in transparency and have a low content of acetaldehyde and oligomer. A small number of injection molded articles, especially bottles, can be obtained. It is particularly suitably used as a beverage container.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08G 63/189 C08G 63/189 63/85 63/85 // B29K 67:00

Claims (5)

[Claims] 1. A thermoplastic polyester (A) having a main repeating unit of ethylene terephthalate and a thermoplastic polyester (B) having a main repeating unit of ethylene naphthalenedicarboxylate in a weight ratio of 44 to 98:
A resin composition comprising 56 to 2 blends, wherein Ge contained in the resin composition is 20 to 90 ppm and Sb is 3 to 110 ppm. 2. A thermoplastic polyester (A) having a main repeating unit of ethylene terephthalate containing 30 to 100 ppm of Ge and 100 pp of Sb.
(A) :( B) = 44 to 50 ppm by weight of a thermoplastic polyester (B) whose main repeating unit is ethylene naphthalenedicarboxylate.
98. The resin composition according to claim 1, wherein the resin composition is blended with 56-2. 3. A molded product obtained by injection molding the resin composition according to claim 1. 4. A bottle obtained by blowing a preform obtained by injection molding the resin composition according to claim 1. 5. A molding machine cylinder in a section from a position where a resin is subjected to a heat shearing treatment in a cylinder to a substantially molten state during injection molding to a position immediately before a molten resin is accumulated at a cylinder tip in a measuring step. 5. The bottle according to claim 4, wherein the bottle is evacuated through at least one vent port provided in the mold, and the inside of the molding machine is evacuated to form the bottle.