JP2652878B2 - Polyester hollow molded body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hollow polyester article excellent in gas barrier properties and transparency.

(Problems solved by the prior art and the invention) Polyethylene terephthalate resin (hereinafter abbreviated as PET)
Thermoplastic polyester resin represented by is a material with excellent mechanical properties, gas barrier properties, chemical resistance, hygiene, etc., and various containers for draft beer and other carbonated beverages, seasonings, cosmetics, pharmaceuticals, etc. It is processed into paper, film, sheet, etc. and is widely used as packaging material. In particular, in recent years, there has been a remarkable use as a hollow container due to improvement in flow molding technology and biaxial stretching blowing technology.

However, a container made of a thermoplastic polyester resin containing PET as a main component has a disadvantage that the gas barrier property is insufficient, and in particular, in the case of a container for beer and carbonated beverage where severe gas barrier property is required, the gas barrier property is increased. Therefore, as a method conventionally used, a method of increasing the wall thickness and a method of using an ethylene-vinyl alcohol copolymer, a polyamide, a vinylidene chloride polymer, an acrylonitrile resin, etc.
There is a method of forming two layers of PET. In the former method of increasing the wall thickness, the basis weight is increased, and in the latter two-layer molding method, it is difficult to regenerate the resin, the waste of the resin increases, the overall material cost increases, and a special two-layer molding method is used. There is a problem that a molding machine is required.

Japanese Patent Application Laid-Open No. 50-45895 discloses a poly (alkylene oxide) having an ether bond and having improved gas barrier properties, but having a number average molecular weight of 600 to 6000.
It is a copolymer of glycol and has poor heat resistance.

Also, those disclosed in JP-A-61-241349, (R ′: divalent aromatic hydrocarbon group) The polyhydroxypolyether represented by the following formula is used as a component unit, and it is particularly characterized by containing a hydroxy group.

An object of the present invention is to develop a polyester hollow molded article having excellent gas barrier properties and melt moldability.

(Means for Solving the Problems) The present invention has the following configuration to achieve the above object.

That is, the present invention provides a hollow molded article obtained by stretching a polyester resin composition comprising a diol component unit containing ethylene glycol as a main component and a dicarboxylic acid component unit containing terephthalic acid or an ester-forming derivative thereof as a main component. A polyester hollow molded article characterized in that more than 5 mol% of diethylene glycol is copolymerized as a diol component unit of the polyester resin composition.

The content of diethylene glycol in the preferred polymer is more than 5 mol% and not more than about 10 mol%.

The dicarboxylic acid component unit used in the resin composition as a raw material of the hollow molded article of the present invention mainly contains a terephthalic acid component unit, and the other dicarboxylic acid component units include isophthalic acid, naphthalenedicarboxylic acid, phthalic acid, and cyclohexane. Aromatic, alicyclic, and aliphatic dicarboxylic acids such as dicarboxylic acid, sebacic acid, azelaic acid, adipic acid, succinic acid, and oxalic acid.

As the diol component unit, in addition to diethylene glycol used in the present invention and ethylene glycol as a main component, 1.3 propanediol, 1.4-butanediol, neopetyl glycol, cyclohexanediol, cyclohexanedimethanol, 1・ 4-bis (β-hydroxyethoxy) benzene, 1.3-bis (β-hydroxyethoxy) benzene, 2.2-bis (4-β-hydroxyphenyl) propane, 2.2-bis (4-β- Hydroxyethoxyphenyl) propane, bis (4-β-hydroxyethoxyphenyl) sulfone, bis (4-β-hydroxyphenyl) sulfone and the like can be used.

In the resin composition, a polyfunctional component unit may be used as a moldability improver, and a polyfunctional component unit having three or more carboxyl groups or hydroxyl groups, or a total of three carboxyl groups and hydroxyl groups may be used. The polyfunctional component unit having the above may be used.

Specifically, trimellitic acid, trimesic acid, 3.
Aromatic polybasic acids such as 3 ', 5,5'tetracarboxydiphenyl, aliphatic polybasic acids such as butane-tetracarboxylic acid, and aromatics such as phloroglucin and 1,2.4,5-tetrahydroxybenzene Examples thereof include aliphatic polyols such as polyol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol, and oxypolycarboxylic acids such as tartaric acid and malic acid.

As the catalyst used for the polymerization of the polyester resin composition, a known catalyst used in the conventional production of PET can be used. These catalysts include antimony,
Metals such as germanium, titanium and niobium or compounds thereof can be used. Specific examples include antimony trioxide, germanium dioxide, tetrabutoxytitanium, and niobate.

In the present invention, conventionally known additives such as heat stabilizers, light stabilizers, antibacterial agents, lubricants, pigments and dyes can be used during the polymerization of polyester. As the transesterification catalyst, metal compounds such as calcium, magnesium, lithium, zinc, cobalt and manganese, hydroxides, halogen compounds, inorganic acid salts, organic acid salts and the like are used. Further, a phosphorus compound such as phosphoric acid, phosphorous acid, hypophosphorous acid or an ester thereof can be used as the heat stabilizer.

As the polymerization method used in the present invention, a known melt polymerization method and solid-state polymerization method can be used. The melt polymerization method is generally used a direct polymerization method or a transesterification polymerization method,
The polymerization is carried out at a temperature of 200 to 280 ° C. and a degree of vacuum of 1 Torr or less. The solid phase polymerization method is to further extend the molecular weight of a polymer obtained by melt polymerization, and is carried out under a vacuum at a temperature of 160 to 240 ° C. below the melting point or under an inert flow. The intrinsic viscosity of the resin composition is 0.5 to 2.0 dl / g, particularly in the case of a hollow molded article, which is 0.1 to 2.0 dl / g.
It is preferably in the range of 7 to 1.5 dl / g, more preferably 0.8 to 1.3 dl / g.

The polymerization degree is usually pelletized, dried to a water content of 0.01% or less, and used for molding. Vacuum drying conditions are 15
Hours or more, preferably at 130 to 150 ° C. for 20 hours or more.
The hollow molded article of the present invention may be uniaxially or biaxially stretched, and its stretching ratio is 1.1 to 10 times in uniaxial stretching, preferably
The range is 1.5 to 7 times, and in the case of biaxial stretching, any of simultaneous or sequential stretching methods may be used.
Times, preferably 1.5 to 6 times. The hollow molded article can be subjected to heat setting depending on the purpose of use.

The polyester hollow molded article of the present invention contains a nucleating agent, an inorganic filler, a lubricant, a slipping agent, an antiblocking agent, a stabilizer, an antistatic agent, an antifogging agent, It does not matter if an appropriate amount of various additives such as is blended.

In producing the polyester hollow molded article of the present invention, the polyester resin composition of the present invention and PET may be pellet-blended. Moreover, you may use for multilayer molding.

When a parison is used as the hollow molded body, it can be performed without any difference from a conventional PET resin hollow molding machine.
For example, extrusion blow molding, which is generally called direct blow, or a molding method called injection blow, in which a parison is blown with a compressed gas before being sufficiently cooled after injection molding, or after forming a parison with a bottomed opening by injection molding or extrusion molding, A molding method called biaxial stretching blow molding in which a parison is stretched at an appropriate temperature, for example, at a temperature of 60 to 160 ° C, and is blow-molded by axial stretching with a stretching rod and circumferential or simultaneous stretching with a compressed gas. Can be used. In the hollow molded body obtained by the above method, the body thin portion is stretched in at least one axial direction.

The stretch ratio is preferably 2 times or more, more preferably 3 times or more in terms of area ratio (axial direction stretch ratio × circumferential stretch ratio). The body thickness of the stretch-blown hollow molded body is usually 100 μm or more, preferably 200 to 1000 μm.
Further, after extrusion molding of an unstretched sheet, a lid was integrated with a hollow molded body formed by deep drawing, or a cylinder obtained by stretching and orienting a pipe formed by extrusion or injection molding in some cases. It may be a plastic can.

More specifically, the hollow molded article of the present invention is a hollow molded article characterized by having excellent gas barrier properties and having less uneven thickness at least in one direction in a thin portion of the body. The polyester resin composition used in the present hollow molded article preferably has crystallinity from the viewpoint of blow moldability, and has an intrinsic viscosity of preferably 0.7 to 1.5 dl / g, more preferably 0.8 to 1.3 dl / g.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. Prior to the description, in Test Examples and Control Examples, changes in gas barrier properties based on the blending ratio of diethylene glycol will be described with reference to gas barrier properties of a film.

The main measuring methods used in the present invention are as follows.

Measurement method of gas barrier properties (oxygen permeability)
(I) Measurement with stretched film (cc · mm / m ² · atm · day) Measurement was performed using a film that was simultaneously stretched 3.5 times vertically and horizontally at 95 ° C.

(Ii) Measurement by hollow molded article (cc / book · atm · day) Measurement was performed using one hollow molded article blow-molded by Nissei ASB50, which is a biaxial stretch blow molding machine.

Diethylene glycol content in chip (mol%)
2.00 g of sample was saponified with 50 ml of 1N KOH methanol solution, neutralized with terephthalic acid, and measured by gas chromatography.

Intrinsic viscosity (dl / g) Phenol / 1.1.1.2.2 Tetrachloroethane = 6/4
(Weight ratio) It measured at 20 degreeC using the mixed solvent.

Test Examples 1 and 2 and Control Examples 1 and 2 10 kg of bishydroxyethyl terephthalate, 6.6 kg of terephthalic acid, diethylene glycol (hereinafter abbreviated as DEG)
419 g (5 mol% based on acid component unit), ethylene glycol 1.43 kg, trimethyl phosphoric acid 4 g (based on polymer
pm), 1.5 g of germanium dioxide (about 100 ppm for polymer)
, And subjected to an esterification reaction at 250 ° C. for 3 hours.
Polyester was obtained by a polycondensation reaction under reduced pressure at 75 ° C. and a degree of vacuum of 0.5 Torr for 4 hours. The intrinsic viscosity was 0.715 dl / g.

The pelletized polyester was vacuum-dried at 140 ° C. for 24 hours, and a 230 μm-thick sheet was formed using a Labo Plastomill manufactured by Toyo Seiki Seisaku-sho, Ltd. Further, the sheet was simultaneously stretched at a stretch ratio of 3.5 times each in the longitudinal and horizontal axes to form a film, and then gas barrier properties were evaluated.

Test Example 2 was the same as Test Example 1 except that the amount of DEG added was 8 mol% based on the acid component unit.
In Comparative Example 2, a film was prepared in the same manner as in Test Example 1, except that DEG was added at 2 mol% based on the acid component unit except that DEG was not added.

Table 1 summarizes the above results. DEG component 3.4 of Control Example 2
In mol%, a remarkable effect is not seen.
When the DEG component exceeds 5 mol% as in 2, the oxygen permeability showing gas barrier properties is clearly improved.

In Example 1, the polyester obtained in the same manner as in Test Example 1 except that the amount of DEG was increased, was further subjected to solid-state polymerization in a vacuum of 205 ° C. × 1 Torr for 26 hours, DEG 10.5 mol%, intrinsic viscosity
0.95 dl / g of polymer is stretched by a biaxial stretch blow molding machine to about 2
It is a hollow molded body having a minimum thickness of 300 μm, which is stretched about 3.3 times and about 3.3 times in width. Comparative Example 1 has a conventional intrinsic viscosity of 0.75 dl / g.
This is a hollow molded article obtained by molding PET (without adding DEG) by the same method.

Comparative Example 2 had an intrinsic viscosity of 1.0 dl / in which 10 mol% of the terephthalic acid component unit of PET was replaced by the isophthalic acid component unit.
g of the copolyester resin molded in the same manner.
It is a hollow molded body. Table 2 summarizes the above results.

Comparative Example 2 was composed of a composition having excellent gas barrier properties, but had a significant uneven thickness and could not be used substantially. Example 1
Has less uneven wall thickness and has better gas barrier properties than the conventional hollow molded body of Comparative Example 1.

(Effect of the Invention) As described above, the polyester hollow molded article of the present invention is excellent in gas barrier properties, melt moldability, and transparency.

Claims (1)

(57) [Claims] A hollow molded article obtained by stretching a polyester resin composition comprising a diol component unit containing ethylene glycol as a main component and a dicarboxylic acid component unit containing terephthalic acid or an ester-forming derivative thereof as a main component. A polyester hollow molded article characterized in that more than 5 mol% of diethylene glycol is copolymerized as a diol component unit of the polyester resin composition.