JPH058283A - Polyester direct blow hollow molded product - Google Patents

Abstract

PURPOSE:To provide a polyester direct blow hollow molded product suitable for a packing molded product requiring gas barrier properties and transparency. CONSTITUTION:A polyester direct blow hollow molded product excellent in gas barrier properties and transparency is obtained using a copolyester resin containing 90-40mol.% of an ethylene-2,6-naphthalate unit and 10-60mol.% of an ethylene isophthalate unit and characterized by that oxygen permeability is 1.5cc.mm/m.day.atm or less and the light transmissivity of the body part thereof is 85% or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester direct blow hollow molded product suitable for a molded product for packaging which requires properties such as gas barrier property and transparency.

[0002]

2. Description of the Related Art Direct blow hollow molded articles made of polyethylene terephthalate resin (hereinafter referred to as PET) have been widely used as molded articles for packaging because of their excellent mechanical strength and transparency.

However, even in such a PET molded product, the gas barrier property against oxygen and the like is not sufficient, and the product of the contents is used when the storage is prolonged and a higher gas barrier property is required such as when the container is small. It has the drawback of reducing its value. Further, when a PET molded product is to be obtained by the direct blow molding method, the melt viscosity must be remarkably increased in order to prevent drawdown during molding which may occur due to its poor melt strength. It has the disadvantage that solid-state polymerization has to be carried out in the process.

As a known method for improving such a defect, the crystallinity of a molded article or PET using a polyethylene 2,6 naphthalate resin (hereinafter referred to as PEN) having an excellent gas barrier property to reduce the crystallinity and melt viscosity characteristics. Improved, for example, KODAR PET of Eastman Chemical Company
Examples include molded articles using G. Copolyester.

However, among such molded products, in the case of a molded product using PEN, since it is a typical crystalline polymer due to the molecular structure of PEN and its melting temperature is as high as 270 ° C., molding during melt extrusion is performed. If the temperature is not raised to high temperature, cloudiness will occur due to the fact that the crystal nuclei cannot be completely melted,
Further, the high temperature causes a problem that the generation of acetaldehyde increases. Also, like PET, solid-state polymerization must be carried out to prevent drawdown during molding, and crystallization will proceed further if solid-state polymerization is carried out. Therefore, unless the molding temperature during melt extrusion is raised to a higher temperature, it becomes cloudy. Is likely to occur, and further, a large defect occurs in the molded product that acetaldehyde is significantly increased. In addition, KODAR. PETG. A molded product using Copolyester has a major drawback that it is inferior to PET in gas barrier property. As described above, there are such drawbacks, and improvement thereof has been desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester direct blow hollow molded article suitable for a molded article for packaging which is required to have excellent gas barrier properties and transparency.

[0007]

SUMMARY OF THE INVENTION The present invention has been made paying attention to such problems, and relates to a polyester direct blow hollow molded article suitable for a molded article for packaging which does not have the above-mentioned defects, and as a result of earnest research, gas barrier property, The present invention has been accomplished by finding a polyester direct blow hollow molded article having excellent transparency and capable of improving the above drawbacks.

That is, the present invention contains 90 to 40 mol% of ethylene-2,6-naphthalate units and 10 to 60 mol% of ethylene isophthalate units and has an oxygen permeability of 1.5.
cc · mm / m · day · atm direct blow blow molding of a copolyester resin of less than, and the gas barrier properties of the hollow molding of the body light transmittance of 85% or more,
It is a polyester direct blow hollow molded product with excellent transparency.

The polyester copolymer resin in the present invention is a copolymer polyester resin containing 90 to 40 mol% of ethylene-2,6-naphthalate units and 10 to 60 mol% of ethylene isophthalate units, and is ethylene-2,6.
-When the naphthalate unit is more than 90 mol%, the transparency of the molded article does not appear because the effects of copolymerization with ethylene isophthalate unit, melting temperature drop and glass transition temperature drop due to randomization, and slowing of crystallization rate do not appear. When the ethylene-2,6-naphthalate unit is less than 40 mol, there is no effect on the moldability, particularly the melting property, and the melting temperature is remarkably lowered, the melt viscosity is lowered, and the casting from the polymerization kettle is remarkably reduced. It will be difficult.

This polyester copolymer resin is 2,6-
Synthesized by combining naphthalenedicarboxylic acid or its ester-forming derivative with isophthalic acid or its ester-forming derivative and ethylene glycol under suitable reaction conditions in the presence of a catalyst. Mol%, preferably 2 mol% or less, in the range of terephthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hydroxybenzoic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 3 , 5-dicarboxybenzenesulfonic acid, oxalic acid, succinic acid, glutaric acid, sebacic acid and the like, and one or more kinds of ester-forming derivatives thereof may be substituted.

Further, a small amount of a part of ethylene glycol such as 1,2-propylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, neopentylene glycol, 1,4-bishydroxybenzene and poly (ethylene glycol) is used. It may be replaced with one kind or two or more kinds of alkylene glycols such as polyethylene glycol, polytetramethylene glycol and polypropylene glycol. In addition, trifunctional or higher functional compounds such as glycerin, pentaerythritol, trimellitic acid and 5-hydroxyisophthalic acid may be used to a certain extent so that the polymer is substantially linear,
Further, it may be replaced with a monofunctional compound such as p-phenylphenol, benzyloxybenzoic acid, naphthalenemonocarboxylic acid, polyethylene glycol monomethylene ether and the like.

The intrinsic viscosity (hereinafter referred to as IV) of the polyester copolymer resin is in the range that can be melt-extruded,
From the mechanical properties of the obtained molded product, IV = 0.3-1.
The range is 0, preferably 0.4 to 0.85.

If necessary, a small amount of another polymer may be added to or mixed with the polyester copolymer resin in the present invention, but in this case, the properties of the polyester copolymer resin are not essentially changed in this case. It is preferable to carry out. Examples of these additives or mixtures include polyamide, polyolefin, and other polyesters. Further, the polyester copolymer resin is, if necessary, a matting agent such as titanium dioxide and alumina oxide, a stabilizer such as phosphoric acid, phosphorous acid and esters thereof, an antioxidant, an ultraviolet absorber, and a fluorescent whitening agent. Agents or additives such as pigments and dyes may be included.

[0014]

In the polyester direct blow hollow molded article using the polyester copolymer resin of the present invention, the gas barrier property of the molded article is improved due to the molecular structure of the copolymer resin component, and the randomization effect by copolymerization causes In addition, the crystallization rate is slowed, and a molded article having good transparency can be obtained. In addition, the randomizing effect of the copolymerization can increase the melt viscosity at a low melting temperature and improve the moldability during direct blow molding.

[0015]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

First, the main methods for measuring physical properties are as follows.

1. Intrinsic viscosity (IV) It was measured at a temperature of 35 ° C. using o-chlorophenol as a solvent.

2. Oxygen transmission rate OX-TRAN100 type oxygen transmission rate measuring instrument (MOCON
(Manufactured by the company) at a temperature of 25 ° C and a humidity of 50% RH.

3. Light transmittance DIRECT. READING. Haze. METER
(Manufactured by Toyo Seiki Seisakusho).

4. Melt pour point (Tf) Measured with a high-performance flow tester (manufactured by Shimadzu Corporation) at a load (P) of 30 kg and a nozzle size of 1.0 mm diameter and 10 mm thickness. Outflow rate (Q) = 10 cm / sec. The melt pour point (Tf) was determined by measuring the cylinder temperature.

5. Melt viscosity (ηa) From the outflow rate (Q) measured with a high-performance flow tester (manufactured by Shimadzu Corporation), load (P) = 30 kg, nozzle size = 1.0 mm diameter and 10 mm thickness

[0022]

[Equation 1]

Then, the melt viscosity (ηa) was calculated.

6. Tensile rupture strength Using a slab-shaped test piece having a width of 5 mm, a tensilon (manufactured by Toyo Ball Doun Co., Ltd.) was used to measure between chucks = 40 mm, tensile speed = 50 mm / min, and temperature 23 ° C.

The polyester copolymer resin, PEN resin and PET resin used are as follows.

1. Polyester Copolymer Resin In an autoclave, the transesterification reaction of 2,6-naphthalenedicarboxylic acid and isophthalic acid with ethylene glycol is carried out in the presence of a catalyst to produce an initial condensate, and this initial condensate is polycondensed. It was obtained. Thus, the following four types of polyester copolymer resins shown in Table 1 were obtained in the autoclave.

[0027]

[Table 1]

2. PEN resin In an autoclave, an ester condensation reaction between 2,6-naphthalenedicarboxylic acid and ethylene glycol was carried out in the presence of a catalyst to produce an initial condensate, which was obtained by polycondensation. IV = 0.6
PEN homopolymer of 1.

3. PET resin manufactured by Nippon Unipet Co. IV = 0.59 and IV = 1.00
PET homopolymer.

[Examples 1 to 4 and Comparative Example 1] Using the above resins, a press sheet molding machine manufactured by SHINTO was used to set molding temperature = 275 to 295 ° C and cooling = 15 ° C (water cooling). Thus, an unstretched sheet molded product having a thickness of about 0.1 mm was obtained. Table 2 shows the evaluation results of the oxygen permeability and the tensile breaking strength of the molded product.

[0031]

[Table 2]

As is clear from Table 2, the oxygen permeability of the present copolyester resin is 1.5 cc.mm/m.day.atm.
The following excellent gas barrier properties are exhibited, and the mechanical strength of the molded product is also excellent.

[Examples 5 to 8 and Comparative Examples 2 to 3] Using each of the above resins, the relationship between the melt viscosity (ηa) and the cylinder temperature was obtained and used for the melt pour point (Tf) and the current direct blow. Solid-state polymerization PET (IV = 1.
Table 3 shows the evaluation results of the cylinder temperature range showing the melt viscosity (ηa = 9000 to 14000 poise) corresponding to the standard molding temperature of 280 to 290 ° C. in 0).

[0034]

[Table 3]

As is clear from Table 3, in the case of the present copolyester resin, the melt pour point is on the low temperature side, so that low temperature melt extrusion is possible and a temperature showing a high melt viscosity equivalent to PET for direct blowing. The range is as wide as PET for direct blow molding, and the high melt viscosity without drawdown, which is indispensable for obtaining direct blow molded products, is stably maintained. Thus, the present copolyester resin has excellent melting characteristics suitable for direct blow molding.

[Examples 9 to 12 and Comparative Examples 4 to 7] Using the above resins, a molding temperature of 240 to 300 ° C. was set by a blow molding machine manufactured by Japan Steel Works, and a cooling temperature of the blow mold was 1
A molded product of a hollow direct blow container was obtained at a setting of 5 ° C. Table 4 shows the molding conditions during the molding and the evaluation results of the light transmittance of the body of the molded product.

[0037]

[Table 4]

As is clear from Table 4, in the case of the present copolyester resin, due to its excellent melting property, the molding condition is good, and the body light transmittance of the molded product is 85% or more. The transparency of the molded product is excellent.

[0039]

The polyester molded product according to the present invention is a novel polyester direct blow hollow molded product which is excellent not only in gas barrier properties and transparency but also in direct blow moldability.

Continuation of front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI technical display location // B29K 67:00 B29L 22:00 4F (72) Inventor Fujio Fujisawa 2-1-1 Katata, Otsu City, Shiga Prefecture No. Toyobo Co., Ltd.

Claims (1)

Claims: 1. Ethylene-2,6-naphthalate unit 9
0-40 mol% and ethylene isophthalate units 10-6
Containing 0 mol% and oxygen permeability of 1.5cc ・ mm / m ・ da
A direct blow hollow molded product of a copolymerized polyelter resin of y · atm or less, and a hollow molded product having a light transmittance of 85% or more in the body, which is excellent in gas barrier properties and transparency, and is a polyester direct blow hollow molded product. ..