JPH04197634A - Multi-layer plastic vessel and its manufacture - Google Patents

Abstract

PURPOSE:To obtain a uniform vessel which possesses transparency and is superior in barrier properties to gas, steam and ultraviolet rays, by a method wherein the title vessel is comprised of at least two layers of thermoplastic polyester of ethylene terephthalate and a thermoplastic polyesterblend layer. CONSTITUTION:A multi-layer plastic vessel is constituted of at least two layers of a thermoplastic polyester layer (layer A) at least 80mol% of which is ethylene terephthalate as a repeating unit and a thermoplastic polyesterblend layer (layer B) consisting essentially of thermoplastic polyester (a) at least 70mol% of which is ethylene isophthalate as a repeating unit and thermoplastic polyester (b) at least 80mol% of which is ethylene naphthalate as a repeating unit. Then to manufacture this multi-layer plastic vessel, a preform comprised of at least two layers A, B is molded by injection molding and the title vessel is obtained by performing orientation blow molding in at least a uniaxial direction within a temperature range of 80-120 deg.C.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention has a uniform wall thickness, is transparent, and has excellent barrier properties against gases such as oxygen and carbon dioxide gas or water vapor, and excellent barrier properties against ultraviolet rays. The present invention relates to a multilayer plastic container and a method for manufacturing the same.

(Prior art and problems to be solved by the invention) Recently, polyethylene naphthalate (PE
N) is attracting attention. PEN has barrier properties against gases such as oxygen and water vapor due to polyethylene terephthalate (
It can also block ultraviolet rays in the 320 to 380 nm range, which cannot be blocked by PET. In addition, it has the same stretchability as PET, and like PET, strong containers can be made by biaxial stretch blow molding.

However, PEN is very expensive due to the complicated manufacturing process of the raw material 2,6-naphthalene dicarboxylic acid or dimethyl 2,6-naphthalene dicarboxylate, and it is difficult to use PEN alone in general-purpose food packaging containers, for example. . Therefore, it would be a great advantage if containers could be made at low cost without reducing the performance of PEN.

One solution to this problem is multilayer molding using PEN. For example, Japanese Patent Application Laid-Open No. 61-279553 describes a PET/PEN multilayer hollow molded product and a method for manufacturing the same. However, the optimum stretching temperature for PET is 80~
120° C., PEN was deviated from around 120 to 160° C., and there was a problem that it was difficult to uniformly stretch and mold a multilayer preform.

(Means for Solving the Problems) As a result of intensive research in order to solve the above problems, the present inventors found that a layer of thermoplastic polyester (layer A) in which 80 mol% or more of repeating units is ethylene terephthalate; A thermoplastic polyester blend layer containing as essential components a thermoplastic polyester (a) in which 70 mol% or more of repeating units are ethylene isophthalate, and a thermoplastic polyester (b) containing 80 mol% or more of ethylene naphthalate as repeating units. A multilayer plastic container consisting of at least two layers (layer B) is transparent, has excellent barrier properties against gases such as oxygen, water vapor, and ultraviolet rays, and is molded into a uniform container with no uneven thickness. It was found that this method was easy to carry out, and the present invention was completed.

That is, the present invention provides a thermoplastic polyester layer (A layer) in which 80 mol% or more of repeating units are ethylene terephthalate, and a thermoplastic polyester layer (A layer) in which 70 mol% or more of repeating units are ethylene isophthalate.
) and a thermoplastic polyester (b) in which 80 mol% or more of repeating units are ethylene naphthalate (b).
A multilayer plastic container comprising at least two layers of A and a method for manufacturing the multilayer plastic container, the method comprising:
A method for producing a multilayer plastic container, which comprises molding a preform consisting of at least two layers, layer B and layer B, by injection molding, and stretching and blow molding the preform in at least one axial direction at a temperature range of 80 to 120"C. It provides:

The thermoplastic polyester containing 80 mol% or more of ethylene terephthalate units as a repeating unit used as a component of layer A in the present invention may also contain other ester repeating units in a range of less than 20 mol%. .

1.5-1 as a dicarboxylic acid component other than terephthalic acid
■, 6-11.7-12.6-12,7-naphthalene dicarboxylic acid, isophthalic acid, phthalic acid, cyclohexanedicarboxylic acid, dibromoisophthalic acid, sodium-sulfoisophthalic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenylketone dicarboxylic acid, diphenoxyethane dicarboxylic acid, aromatic dicarboxylic acids such as phenylenedioxydiacetic acid, adipic acid, sebacic acid, succinic acid,
Glutaric acid, piperic acid, schelic acid, azelaic acid,
Examples include aliphatic dicarboxylic acids such as undecadionic acid and dodecadionic acid, either alone or in a mixture of two or more.

In addition, as diol components other than ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, phlopylene glycol, neopentyl glycol,
Aliphatic glycols such as diethylene glycol and polyethylene glycol, alicyclic glycols such as cyclohexane dimetatool, aromatic glycols such as o 1 m + p-xylene glycol, 2,2-bis(4-hydroxyethoxyphenyl)propane, etc. alone or A mixture of two or more types may be mentioned.

Furthermore, hydroxycarboxylic acids such as glycolic acid, hydroxybenzoic acid, and hydroxynaphthoic acid, and diphenols such as hydroquinone, resorcinol, dihydroxydiphenyl, and dihydroxydiphenyl ether may be copolymerized.

The intrinsic viscosity (phenol/tetrachloroethane; weight ratio 6/4.25°C) of the thermoplastic polyester in which 80 mol% or more of repeating units are ethylene tereclate units used in the present invention is preferably 0.5 dl/g or more. . If it is less than 0.5 dl/g, the mechanical properties of the obtained multilayer container will deteriorate, which is not preferable.

Thermoplastic polysteel containing 70 mol% or more of ethylene isophthalate units as a repeating unit that can be used as component (a) of layer B of the present invention/L/C, and 30 others
It may contain other ester repeating units in an amount less than mol%. Dicarboxylic acid components other than isophthalic acid include 1,5-11.6-11,7-12,6-32,7-naphthalenedicarboxylic acid, terephthalic acid, phthalic acid, cyclohexanedicarboxylic acid, dibromoisophthalic acid, and sodium-sulfoisophthalic acid. acids, aromatic dicarboxylic acids such as diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, diphenoxyethane dicarboxylic acid, phenylene dioxy diacetic acid, adipic acid, sebacic acid,
Examples include aliphatic dicarboxylic acids such as succinic acid, glutaric acid, piperic acid, speric acid, azelaic acid, undecadionic acid, and dodecadionic acid, either alone or in a mixture of two or more.

In addition, diol components other than ethylene glycol include trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, propylene glycol, neopentyl glycol,
Aliphatic glycols such as diethylene glycol and polyethylene glycol, alicyclic glycols such as cyclohexane dimetatool, o, m, p-xylene glycol, 2,2
-Bis(4-hydroxyethoxyphenyl)propane and other aromatic glycols may be used alone or in a mixture of two or more.

Furthermore, hydroxycarboxylic acids such as glycolic acid, hydroxybenzoic acid, and hydroxynaphthoic acid, and diphenols such as hydroquinone, resorcinol, dihydroxydiphenyl, and dihydroxydiphenyl ether may be copolymerized.

The intrinsic viscosity (phenol/tetrachloroethane; weight ratio 6/4.25°C) of the thermoplastic polyester in which 70 mol% or more of repeating units are ethylene isophthalate units used in the present invention is preferably 0.4 dl/g or more. . If it is less than 0.4 dl/g, the mechanical properties of the obtained multilayer container will deteriorate, which is not preferable.

The thermoplastic polyester containing 80 mol% or more of ethylene naphthalate units as repeating units used as component (b) of the B layer of the present invention may contain 2.6 mol% or more of ethylene naphthalate units as other dicarboxylic acid components in a range of less than 20 mol%. - isomer of naphthalene dicarboxylic acid 1,5-11,6-11,7
-32,6-12.7-naphthalenedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, cyclohexanedicarboxylic acid, dibromoisophthalic acid, sodium-sulfoisophthalic acid, diphenyldicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenyl Aromatic dicarboxylic acids such as ketone dicarboxylic acid, diphenoxyethane dicarboxylic acid, and phenylene dioxy diacetic acid, adipic acid, sebacic acid, succinic acid, glutaric acid, piperic acid, schelic acid, azelaic acid, undecadionic acid, dodecadionic acid, etc. A single aliphatic dicarboxylic acid or a mixture of two or more thereof may be added.

In addition, diol components other than ethylene glycol include trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, propylene glycol, neopentyl glycol,
Aliphatic glycols such as diethylene glycol and polyethylene glycol, alicyclic glycols such as cyclohexane dimetatool, O+m+p-xylene glycol, 2,2
-Bis(4-hydroxyethoxyphenyl)propane and other aromatic glycols may be used alone or in combination of two or more.

Furthermore, hydroxycarboxylic acids such as glycolic acid, hydroxybenzoic acid, and hydroxynaphthoic acid, and diphenols such as hydroquinone, redulcinol, dihydroxydiphenyl, and dihydroxydiphenyl ether may be copolymerized.

The intrinsic viscosity (phenol/tetrachloroethane: weight ratio 6/4.25° C.) of the thermoplastic polyester in which 80 mol% or more of repeating units are ethylene naphthalate units used in the present invention is preferably 0.3 dl 7 g or more. If it is less than 0.3 dl/g, the mechanical properties of the obtained multilayer container will deteriorate, which is not preferable.

The blend ratio of layer B, that is, a thermoplastic polyester (a) in which 70 mol% or more of repeating units is ethylene isophthalate, and a thermoplastic polyester (b) in which 80 mol% or more of repeating units is ethylene naphthalate.
It is preferable that the blend ratio is the following weight ratio.

Weight ratio of a and b; 99-5:1-95 Weight ratio of thermoplastic polyester (b) in which 80 mol% or more is ethylene naphthalate as a repeating unit is 1%
If it is below, the effect on the barrier property against ultraviolet rays will be small, and if the weight ratio is 95% or more, the optimum stretching temperature of the blend layer will be 120"C or higher, and the optimum stretching temperature of the A layer (80 to 120"C) will be lower. Misalignment makes it difficult to mold a multilayer container with uniform wall thickness, which is undesirable.

In the present invention, layer B consists of a thermoplastic polyester (a) containing 70 mol% or more of ethylene isophthalate as the repeating unit and a thermoplastic polyester (a) containing 80 mol% or more of ethylene naphthalate as the repeating unit.
This is a thermoplastic polyester blend layer which contains b) as essential components and may contain thermoplastic polyesters other than these.

Examples of thermoplastic polyesters other than the above (a) and (b) include polyethylene terephthalate-based polyesters.

The blending amount of the thermoplastic polyester other than these (a) and (b) is preferably 0 to 30% by weight based on the total resin of the B layer.

The resins of layer B may be blended by melt blending in advance or by tri-blending in a hopper of a molding machine. In the case of rough melt blending, any of, for example, a screw extruder, twin screw extruder, open roll, kneader, mixer, etc. can be employed.

The temperature for melt blending varies depending on the type of polyester used, but it ranges from softening temperature + 10°C to softening temperature + 100°C.
'C range is preferred.

Furthermore, an adhesive resin, a coloring agent, an oxidation stabilizer, an ultraviolet absorber, an antistatic agent, a flame retardant, etc. can be added to either layer A or layer B to the extent that the stretchability is not impaired.

The structure of a multilayer plastic container may be at least two layers, layer A and layer B. One layer is a two-layer structure in which layer A is an outer layer and layer B is an inner layer, and the other is a two-layer structure in which layer A is an inner layer and layer B is an outer layer.
Preferred layer structure is a three-layer structure in which layer A is the outermost layer and layer B is the middle layer, and a three-layer structure in which layer B is the outermost layer and layer A is the middle layer. Furthermore, an adhesive layer may be provided between each glabella. It is possible.

The weight proportion of layer B is 1 to 90% by weight, especially 5 to 60% by weight.
is preferred.

Further, in order to improve the transparency of the container and the barrier properties against gases such as oxygen and carbon dioxide, and water vapor, it is preferable to stretch the container in at least one axial direction. For this purpose, the container of the present invention is
A preform (preformed body) consisting of at least 2N of layer and B layer is molded by injection molding, and this is
It is manufactured by stretch blow molding in at least one axis at a temperature range of .degree.

If the stretching temperature is 80° C. or lower, both the hemi layer and the B layer have high elastic moduli and cannot be stretched uniformly. On the contrary, 1
If the temperature is 20° C. or higher, the hemilayer will crystallize, and even in this case, it will no longer be possible to stretch the film uniformly.

(Effects of the invention) The multilayer plastic container according to the invention has a uniform wall thickness,
It is transparent and has excellent barrier properties against gases such as oxygen and carbon dioxide, water vapor, and ultraviolet rays, and can be particularly suitably used as food packaging containers.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples, but these Examples are not intended to limit the present invention in any way.

The test methods used in Examples and Comparative Examples are as follows.

- Uniformity of container wall thickness The thickness of the container body was measured at several locations and evaluated based on the degree of variation from the average value.

○...6. The width of variation is less than 5% of the average value △・
・・・Width of variation is 5 to 50% of the average value x 01
．．・Width of variation is 50% or more compared to the average value ・Oxygen permeability of container Gas permeability measuring device GPM25 manufactured by Gascro Industries Co., Ltd.
The oxygen permeability coefficient of the container was measured at 23° C. and 1 normal pressure. In order to compare the measured values of various containers, the oxygen permeability coefficient (unit: cm2mm/m224h) is calculated by dividing the surface area value of each container and then multiplying it by the average value of the flesh pressure of each container.
ATM).

- Water vapor permeability of container The container filled with calcium chloride and sealed was left in a room at 40° C. and 90% relative humidity. The weight of the container was measured every other day to determine the weight increase per day. In order to compare the measured values of various containers, the water vapor permeability (unit: g
mm/m224h).

- Measurement of ultraviolet transmittance A part of the sample was cut out from the container using a spectrophotometer U-Sea 265FW manufactured by Shimadzu Corporation, and the wavelength of the transmitted light was examined.

Examples 1 to 3 Polyethylene isophthalate (intrinsic viscosity 0.66 dl/g) and polyethylene naphthalate (intrinsic viscosity 0.68 dl/g) were used as thermoplastic polyesters at a weight ratio of 8.
Polyethylene terephthalate (intrinsic viscosity: 0
．． 75dl/g) is the outermost layer and innermost layer, and the blend resin is the middle layer.Outer diameter 27mm, length 115mm, wall thickness 3I
A multilayer preform of IIli was molded by injection molding. The molding conditions at that time were that the cylinder temperature of the injection molding machine for polyethylene terephthalate was set at 260 to 280°C, and the cylinder temperature of the injection molding machine for blend resin was set at 2.
The set temperature of one mold was 60-290°C 20-40°C.

Subsequently, biaxial stretch blow molding was performed at 100°C, and the capacity was 60.
A cylindrical container with a diameter of 0 m1, a body diameter of 60 mm, a height of 220 mm, and a mouth diameter of 27 mm was molded. As the molding machine, an injection blow molding machine manufactured by Mekkei Nisbee Machinery Co., Ltd. was used.

Three types of containers with different thickness ratios of each layer were molded, and Example 1
~3. Table 1 shows the test results for each container.

Example 4 The weight ratio of blended resins is 50=5 of polyethylene isophthalate (intrinsic viscosity 0.66 dl/g) and polyethylene naphthalate (intrinsic viscosity 0.68 dl/g)
Molding was carried out in the same manner as in Example 1 except that the temperature was 0.

Table 1 shows the test results for the molded containers.

Example 5 Same as Example 1 except that the weight ratio of the blended resin was 25 near 5 of polyethylene isophthalate (intrinsic viscosity 0.66 dl/g) and polyethylene naphthalate (intrinsic viscosity 0.68 dl/g). Molded.

Table 1 shows the test results for the molded containers.

Example 6 The weight ratio of the blended resins was 80:80: polyethylene terephthalate/polyethylene isophthalate (20:80) copolymer (intrinsic viscosity 0.74 dl/g) and polyethylene naphthalate (intrinsic viscosity 0.68 dl/g). 20
Molding was carried out in the same manner as in Example 1, except that.

Table 1 shows the test results for the molded containers.

Example 7 The ratio of blended resins was determined by weight ratio of polyethylene naphthalate/polyethylene isophthalate (20:80) copolymer (intrinsic viscosity 0.78 dl/g) and polyethylene naphthalate (intrinsic viscosity 0.68 dl/g). Molding was carried out in the same manner as in Example 1 except that the ratio was 80:20.

Table 1 shows the test results for the molded containers.

Comparative Examples 1 to 3 Same as Examples 1 to 3 except that only polyethylene naphthalate was used instead of the blend resin, polyethylene terephthalate (intrinsic viscosity 0.75 dl/g) was used as the outermost layer, polyethylene naphthalate (intrinsic viscosity 0. .68dl
/g) as the intermediate layer, and three types of multilayer containers with different thickness ratios of each layer were molded.

Table 1 shows the test results for the molded containers.

Comparative Example 4 A multilayer container was formed in the same manner as in Example 1 except that the stretching temperature was 75°C. Table 1 shows the test results for the molded containers.

Comparative Example 5 A multilayer container was molded in the same manner as in Example 1 except that the stretching temperature was 130°C. Table 1 shows the test results for the molded containers.

Comparative Example 6 Polyethylene terephthalate (intrinsic viscosity 0.75 dl/
A single-layer container was formed in the same manner as in Example 1 except that only g) was used. Table 1 shows the test results for the molded containers.

From the test results in Table 1, it can be seen that the molded product according to the present invention has better oxygen permeability and water vapor permeability of the container than the molded product of the comparative example.

Claims (1)

[Claims] 1. A layer (A layer) of thermoplastic polyester in which 80 mol% or more of repeating units are ethylene terephthalate, and a thermoplastic polyester (a) in which 70 mol% or more of repeating units are ethylene isophthalate. A multilayer plastic container comprising at least two layers of a thermoplastic polyester blend layer (B layer) containing as an essential component a thermoplastic polyester (b) in which 80 mol % or more is ethylene naphthalate as a repeating unit. 2 The blend ratio of thermoplastic polyester (a) and thermoplastic polyester (b) in layer B is (a):(b)
)=99-5:1-95 (weight ratio). The multilayer plastic container according to claim 1. 3 A layer of thermoplastic polyester (layer A) in which 80 mol% or more of the repeating unit is ethylene terephthalate, a thermoplastic polyester (a) in which 70 mol% or more of the repeating unit is ethylene isophthalate, and 80 mol% or more of the repeating unit. A preform consisting of at least two thermoplastic polyester blend layers (layer B) containing thermoplastic polyester (b) which is ethylene naphthalate as an essential component is molded by injection molding, A method for producing a multilayer plastic container, characterized by stretch blow molding in at least one axial direction within a temperature range.