JPH10100237A - Hollow container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make transparency, heat resistance and gas barrier properties excellent by solving a problem which polyethylene naphthalate possesses wherein whitening occurs when a polyethylene naphthalate resin is molded into a hollow container. SOLUTION: A hollow container consisting of a resin compsn. contg. a polyethylene nephthalate resin and comprising a trunk part and a bottom part is a container wherein at an arbitrary measuring point on the outer periphery of the trunk part of the container, when birefringence in one direction (direction X) on the outer peripheral face of the measuring point is Δnx and birefringence in the direction (direction Y) at right angles to the above described direction on the outer peripheral face is Δny, Δnx and Δny are at least 0.05 and Δnx/Δny is 0.7-1.3. The hollow container like this has a haze of the trunk part of at most 8%. The hollow container is prepd. by performing injection molding of a resin compsn. contg. polyethylene naphthalate to obtain a preliminary molding and then, performing simultaneous stretch blow molding in length and peripheral directions while the preliminary molding is heated at 120-150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container made of polyethylene naphthalate resin having excellent transparency, heat resistance and gas barrier properties.

[0002]

2. Description of the Related Art In recent years, juices mainly made of glass containers,
Containers for carbonated beverages, beer, sake, cosmetics, soy sauce, and the like are being converted into various plastic containers. It is an object of the present invention to overcome the drawbacks of glass containers such as inconvenience in handling such as fragility and heavyness of glass containers and soaring transportation costs by switching to plastic containers. In particular, polyethylene terephthalate resins are widely used as containers for juices, carbonated drinks, beer, sake, cosmetics, soy sauce, etc. because of their excellent moldability, mechanical properties, and transparency.

[0003] However, for containers that require long-term preservation of the contents filled by high-temperature filling for the purpose of sterilizing the contents, containers made of polyethylene terephthalate resin are likely to be deformed during high-temperature filling. In addition, they have disadvantages such as low gas barrier properties and poor long-term storage properties.

On the other hand, it is known that polyethylene naphthalate resin has a higher glass transition temperature than polyethylene terephthalate resin and has excellent heat resistance and high gas barrier property. That is, JP-A-52-45466, JP-A-4-39052, and JP-A-4-331.
No. 255 describes that polyethylene naphthalate resin has good gas barrier properties and heat resistance.

[0005] As described above, polyethylene naphthalate resin is superior to polyethylene terephthalate resin in properties such as heat resistance and gas barrier properties. However, on the other hand, polyethylene naphthalate resin has a rigid structure in a polymer chain, so that a container is formed. It has the drawback that it is easy to whiten and has poor transparency. Such a drawback may be a fatal drawback because the polyester resin container is characterized by good transparency.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a whitening agent for molding into a hollow container of a polyethylene naphthalate resin having excellent heat resistance and gas barrier properties. It is an object of the present invention to solve the problem described above and to obtain a hollow container having excellent transparency.

[0007]

Means for Solving the Problems The present inventors diligently studied blow molding conditions in order to obtain a hollow container having excellent transparency while making use of the gas barrier properties and heat resistance properties of polyethylene naphthalate resin. This led to the present invention.

The present invention provides (1) a hollow container comprising a resin composition containing a polyethylene naphthalate-based resin and comprising a body and a bottom, wherein the hollow container has an arbitrary shape on the outer periphery of the body. At the measurement point, the birefringence in one direction (X direction) on the outer peripheral surface of the measurement point was Δnx, and the birefringence in the direction perpendicular to the direction (Y direction) on the outer peripheral surface was Δny. In this case, the present invention relates to a hollow container, wherein Δnx and Δny are 0.05 or more, and Δnx / Δny is 0.7 to 1.3. A preferred embodiment is as follows. (2) The hollow container according to the above (1), wherein the haze of the trunk is 8% or less. (3) A resin composition containing a polyethylene naphthalate-based resin is injection-molded to obtain a preform, and then the preform is heated at 120 to 150 ° C. and stretch blow-molded simultaneously in the length direction and the circumferential direction. Above (1) or above
The hollow container of (2).

Hereinafter, the present invention will be described in detail. The molded container of the present invention comprises a resin composition containing a polyethylene naphthalate resin. The polyethylene naphthalate resin used in the present invention contains ethylene-2,6-naphthalate units preferably in an amount of 60 mol% or more, more preferably 7 mol% or more.
More than 5 mol%, more preferably more than 85 mol%. By including this unit in an amount of 60 mol% or more, the resulting hollow container is provided with excellent heat resistance and gas barrier properties. If necessary, ethylene glycol, 2,6
-A copolymer component other than naphthalenedicarboxylic acid may be contained within a range that does not impair the performance of the hollow container of the present invention.

The copolymerized acid component includes terephthalic acid, isophthalic acid, 2,7-naphthalenedicarboxylic acid, 1,5-
Naphthalenedicarboxylic acid, hexahydroterephthalic acid,
Hexahydroisophthalic acid, succinic acid, adipic acid, sebacic acid, p-oxybenzoic acid, 4-4′-biphenyldicarboxylic acid, and ester-forming derivatives thereof, but terephthalic acid, isophthalic acid, hexahydroterephthalic acid preferable.

The copolymerized glycol components include propylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, neopentyl glycol,
1,4-bis (β-hydroxyethoxy) benzene,
There are 1,4-bis (β-hydroxyethoxyphenyl) sulfone, 2,2′-bis (p-β-hydroxyethoxyphenyl) propane, polyalkylene oxide glycol, diethylene glycol, and the like. Methylene glycol, 1,4-cyclohexanedimethanol and neopentyl glycol are preferred.

Trimellitic acid as a polyfunctional copolymer component,
An acid component such as pyromellitic acid, and a glycol component such as glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol may be contained in a small amount, for example, to such an extent that substantially linearity is maintained.

In the copolymerization reaction, Sb, Ge, Ti, S
Oxides such as n, Zn, Mn, Co, Ca, and Mg, hydroxides, lower aliphatic carboxylate salts, alkoxides, and the like can be used as the catalyst.

The intrinsic viscosity of the polyethylene naphthalate resin is preferably 0.4 to 1.1 dl from the viewpoint of moldability and the like.
/ G, more preferably 0.5 to 1.0 dl / g.

Further, from the viewpoint of moldability, heat resistance and mechanical strength (particularly during heat setting), when the temperature is raised at a rate of 20 ° C./min with a differential scanning calorimeter (DSC) of polyethylene naphthalate resin. The elevated crystallization temperature is preferably 15
The temperature is 0 ° C or higher, more preferably 160 to 230 ° C, and particularly preferably 170 to 220 ° C.

The resin composition may contain a stabilizer, for example, phosphoric acid, phosphorous acid, hypophosphorous acid, trimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributyl phosphate, triphenyl phosphate, trimethyl phosphate Phosphorus compounds such as phosphite, triethyl phosphite, tripropyl phosphite, tributyl phosphite, and triphenyl phosphite can be used.

The hollow container of the present invention is first preliminarily molded by melting and mixing a stabilizer and other additives as necessary with a polyethylene naphthalate resin. As the molding method,
Although not particularly limited, an injection molding method, an extrusion molding method, or the like is employed.

Next, the preform is stretch blown to obtain a hollow container. In this stretch blow molding, the obtained hollow container has Δnx and Δny of 0.05 or more, Δnx
/ Δny is 0.7 to 1.3, so that 120 to 15
It is preferable that the film is stretched at 0 ° C., preferably 130 to 140 ° C., simultaneously in the length direction and the circumferential direction. This temperature is 1
When the temperature is lower than 20 ° C., the shape of the obtained container is deteriorated. On the other hand, when the temperature is higher than 150 ° C., the thickness of the obtained container tends not to be uniform, which is not preferable. Further, when the stretching in the length direction and the stretching in the circumferential direction are not simultaneous, Δnx / Δny is less than 0.7 or more than 1.3, so that the degree of orientation in a specific direction is increased and the transparency of the obtained container is poor, which is not preferable. . Here, the "length direction" refers to the vertical direction when the plug portion of the obtained hollow container is turned upward, and the "circumferential direction" refers to the direction perpendicular to the "length direction", that is, the horizontal direction. Good,
This refers to the direction of one horizontal circumference of the outer periphery of the container when the plug portion of the obtained hollow container is facing upward.

The thus manufactured hollow container of the present invention has a birefringence in one direction (X direction) on the outer peripheral surface of the measuring point at an arbitrary measuring point on the outer periphery of the body of the container. When the refractive index is Δnx and the birefringence in the direction perpendicular to the direction on the outer peripheral surface (Y direction) is Δny,
nx and Δny are 0.05 or more, preferably 0.10
And Δnx / Δny is 0.7 to 1.3, preferably 0.8 to 1.2. If Δnx or Δny is less than 0.05, the gas barrier properties and heat resistance of the resulting container will be poor. In addition, Δnx / Δny is 0.
If it is less than 7 or more than 1.3, the transparency of the container from which a large degree of orientation in a specific direction is obtained becomes poor. Δ
In order for nx and Δny to satisfy the above conditions, a method of stretch blow-molding the preform under the above conditions is employed.

The haze of the hollow container of the present invention is further preferably 8% or less, more preferably 5% or less. If the haze is more than 8%, the resulting molded article has poor transparency. In order to reduce the haze to 8% or less, the preform is stretch blow-molded under the conditions described above, and Δnx, Δny,
A method in which Δnx / Δny is set in the above range is employed.

Therefore, the hollow container of the present invention is excellent in transparency, gas barrier properties and heat resistance.
It is suitably used for containers such as juice, carbonated beverages, beer, sake, cosmetics, and soy sauce.

[0022]

Next, the present invention will be described specifically with reference to examples. In addition, various measurement methods in the present invention were measured as follows. 1. Haze A sample is cut out from the body (thickness of about 0.4 mm) of the hollow container, and DIRECT. READING. HAZE. MET
Haze (%) was measured by ER (manufactured by Toyo Seiki Seisaku-sho, Ltd.). 2. Birefringence The center part of the body of the hollow container is cut out at multiple locations (2 cm x
2cm) A sample for refractive index measurement, and the birefringence in an arbitrary direction on the sample at an arbitrary measurement point, that is, an X direction, and a direction perpendicular to the X direction on the sample, that is, a Y direction, is measured by an Appe refractometer. Was measured by The central part of the body of the hollow container refers to the vicinity of the half height of the hollow container except for the plug. 3. Intrinsic intrinsic viscosity IV It was measured with an Ubbelohde viscometer at a temperature of 30 ° C. in a mixed solvent of 1,1,2,2-tetrachloroethane / p-chlorophenol (1: 3 weight ratio). 4. Heated crystallization temperature (Tc1) Differential scanning calorimeter (manufactured by DSC Seiko Instruments Inc.)
The sample was heated at a rate of 20 ° C./min and measured.

Example 1 Polyethylene naphthalate resin (IV: 0.885d)
l / g) using an injection molding machine (M-10, manufactured by Meiki Seisakusho).
0 type) to obtain a preform having a weight of 57 g. A stretch blow molding machine (CORPOLAST) is used for the obtained preformed body.
Stretching temperature of 130 to 140
At the same time, the preformed body was stretch blow-molded in the length direction and the circumferential direction at the same time to obtain a biaxially stretched hollow container. The obtained hollow container was evaluated. Table 1 shows the results. In addition, the angle x (0 ≦ x <360) between the X direction and the horizontal direction (circumferential direction) of an arbitrary measurement point on the body of the hollow container and △ nx / △ n
A graph showing the relationship of y is shown in FIG. △ nx / △ ny
Ranges from 0.83 to 1.20, and the haze is also 3.
0%, and Δnx of the measurement point was 0.05 or more in any direction as shown in FIG. 2, indicating that the container was a hollow container having excellent transparency.

Example 2 Using a polyethylene naphthalate resin shown in Table 1, a hollow container was obtained in the same manner as in Example 1. The obtained hollow container was evaluated. Table 1 shows the results. The range of Δnx / Δny was 0.81 to 1.20, the haze was 5.1%, and the hollow container was excellent in transparency.

Comparative Examples 1 and 2 Preforms were obtained in the same manner as in Example 1 using the polyethylene naphthalate resins shown in Table 1. The obtained preform was stretched in the length direction of the preform at a stretching temperature of 130 to 140 ° C., and then stretched in the circumferential direction at the same temperature to obtain a biaxially stretched hollow container. The obtained hollow container was evaluated. Table 1 shows the results. △ nx / △ ny
Ranges from 0.21 to 4.81 and 0.53 to 1.1, respectively.
56, and the haze greatly exceeds 8%. As shown in FIG. 3, in the hollow container of Comparative Example 1, Δnx of the measurement point is less than 0.05 in a certain direction, and the hollow container is transparent. It was a hollow container with poor properties.

[0026]

[Table 1]

[0027]

As is clear from the above description, according to the present invention, transparency, heat resistance,
A hollow container having excellent gas barrier properties can be obtained.

[Brief description of the drawings]

FIG. 1 shows the relationship between the angle x between the X direction and the horizontal direction and Δnx / Δny at an arbitrary measurement point on the outer peripheral surface of the body of the hollow container obtained in Example 1 and Comparative Example 1 of the present invention. It is a graph showing the relationship.

FIG. 2 is an angle x between an X direction and a horizontal direction at an arbitrary measurement point on the outer peripheral surface of the body of the hollow container obtained in Example 1.
6 is a graph showing the relationship between and nx.

FIG. 3 is an angle x between an X direction and a horizontal direction at an arbitrary measurement point on the outer peripheral surface of the body of the hollow container obtained in Comparative Example 1.
6 is a graph showing the relationship between and nx.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FIB29L 22:00 (72) Inventor Shinichi Kodera 2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo Co., Ltd. Research Laboratory

Claims (3)

[Claims] 1. A hollow container comprising a resin composition containing a polyethylene naphthalate-based resin, comprising a body and a bottom, wherein at a given measurement point on the outer periphery of the body of the container, One direction (X
Δnx and Δny are 0.05 or more and Δn when the birefringence in the direction (Y direction) on the outer peripheral surface is Δny and the birefringence in the direction perpendicular to the direction on the outer peripheral surface (Y direction) is Δny.
x / Δny is 0.7 to 1.3. 2. The hollow container according to claim 1, wherein the haze of the body is 8% or less. 3. A preform is obtained by injection molding a resin composition containing a polyethylene naphthalate-based resin, and then simultaneously stretched in the length direction and the circumferential direction while heating the preform at 120 to 150 ° C. 3. The hollow container according to claim 1, which is formed by blow molding.