JPH0444562B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a parison having a multilayer structure, and more particularly, to a method for manufacturing a parison having a multilayer structure.
The present invention relates to a method for producing a multilayer parison, which is a precursor for obtaining a multilayer container with excellent gas barrier properties and mechanical strength.

In recent years, hollow containers made of thermoplastic resin have been used for cosmetics, etc. due to their light weight and safety against bursting.
Widely used as containers for food, drinks, etc.

In particular, the development of hollow containers made of polyethylene terephthalate is progressing rapidly due to improvements in biaxial stretch blow molding technology.

However, biaxially oriented containers made of thermoplastic polyester resin mainly composed of polyethylene terephthalate do not have perfect performance, especially when the contents are beverages that require high gas barrier properties. In some cases, they have drawbacks such as impairing the flavor of the contents due to insufficient gas barrier performance against oxygen and carbon dioxide.

Conventional technology In order to solve these drawbacks, thermoplastic polyester resin and meta-xylene group-containing polyamide resin (hereinafter referred to as MX), which is a thermoplastic gas barrier resin, were developed.
Using a molding machine with two injection cylinders, one for each type of nylon, the molten thermoplastic polyester resin and MX nylon are injected into a single mold in one clamping operation. Continuously and sequentially inject polyester resin and MX nylon in that order to form thermoplastic polyester resin on the outer layer.
Attempts to create a three-layer structure with MX nylon as the central layer are already known. (Unexamined Japanese Patent Publication No. 57-128516, No. 57
-128520) Problems to be Solved by the Invention However, in the case of this multilayer container, gas barrier resins including MX nylon inherently have poor affinity with thermoplastic polyester resins, etc., so adhesive strength is insufficient. There was a drawback that it was easy to peel off.

As a result of extensive research in view of these drawbacks of conventional methods, the present inventors added an injection cylinder compatible with thermoplastic adhesive resins to the above-mentioned method. By sequentially and sequentially injecting,
We succeeded in forming a thin and uniform thermoplastic polyester resin layer between the thermoplastic polyester resin layer and the MX nylon layer, and as a result of further research, we arrived at the present invention.

Means for Solving the Problems Accordingly, the present invention provides thermoplastic polyester resin,
Polyolefin resin, polycarbonate, polyacrylonitrile, polyvinyl chloride or polystyrene (resin A), thermoplastic adhesive resin (resin B)
and a thermoplastic gas barrier resin (resin C), using a molding machine with three injection cylinders corresponding to each, into a single mold with one mold clamping operation,
Melted resin A, resin B, and resin C, resin A,
Continuously and sequentially injecting resin B and resin C in this order,
Finally, resin A is post-coated to replace the gate portion layer of the parison with resin A, and the body portion is made of resin B between the two outer layers made of resin A and the center layer made of resin C. This is a method for manufacturing a multilayer parison having a five-layer structure in which two adhesive layers are formed, and at least the mouth opening portion has a single structure.

The present invention will be explained below based on the drawings.

FIG. 1 is a principle diagram of an apparatus for implementing the method of the present invention, in which 1, 2, and 3 are injection cylinders for injecting resin A, resin B, and resin C, respectively, and 4 is an injection cylinder for injecting resin A, resin B, and resin C, respectively. Hot runner, 5 is gate,
6 represents a mold, and 7 represents a cavity.

2 to 5 are cross-sectional views showing step by step the situation inside the cavity when carrying out the present invention, and 8, 9 and 10 are resin A, resin B, respectively.
and represents resin C.

Resin A, resin B, and resin C in a molten state in each of the injection cylinders 1, 2, and 3 pass through the gate 5 in the order of resin A, resin B, and resin C.
The parison-shaped cavity 7 is continuously formed in the mold 6.
Inject sequentially.

A check valve is provided in front of the confluence point of the resin flow path.

First, from the injection cylinder 1, the molten resin A
into the cavity, equivalent to 40 to 80% of its capacity.

The internal cross section of the cavity at this time is as shown in Figure 2.

Subsequently, the molten resin B is injected into the cavity from the injection cylinder 2 in an amount corresponding to 1 to 5% of its capacity.

The internal sectional view of the cavity at this time is as shown in FIG.

Subsequently, molten resin C is injected into the cavity from the injection cylinder 3 in an amount corresponding to 16 to 50% of its capacity.

As a result, five resin layers are formed in the cavity as shown in FIG.

Next, a small amount of resin A is again injected from the injection cylinder 1 to convert the outermost layer near the gate of the parison to resin A and replace the flow path with resin A, as shown in FIG.

When the mold is opened after holding pressure and keeping it cold, the body part has five layers, two outer layers made of resin A and a center layer made of resin C, with two adhesive layers made of resin B formed between them. A multilayer parison is obtained, which has a single structure at least in the mouth opening portion.

Generally, the wall thickness of a multilayer parison is 2 to 6 mm, preferably 3 to 5 mm, and the wall thickness of a biaxially stretched and blow-molded multilayer container is 200 to 500 μm, preferably
It is 250-450μ.

Resin A used in the present invention includes thermoplastic polyester resin, polyolefin resin, polycarbonate, polyacrylonitrile, polyvinyl chloride,
or polystyrene, among which thermoplastic polyester resins are preferred.

Such a thermoplastic polyester resin usually has an acid component of 80 mol% or more, preferably 90 mol% or more of terephthalic acid, and a glycol component of 80 mol% or more.
The above means a polyester in which 90 mol% or more is preferably ethylene glycol, and the remaining acid components include isophthalic acid, diphenyl ether-4,4-dicarboxylic acid, naphthalene-1,4- or 2,6- Dicarboxylic acid, adipic acid, sebacic acid, decane-1,10-dicarboxylic acid, hexahydroterephthalic acid, and other glycol components include propylene glycol, 1,4-butanediol, neopentyglycol, diethylene glycol, and cyclohexanedimethanol. , 2,2-bis(4-hydroxyphenyl)propane, 2,2-
Bis(4-hydroxyethoxyphenyl)propane and the like can be exemplified. Furthermore, polyester resins containing P-oxybenzoic acid or the like as the oxyacid may also be exemplified.

The intrinsic viscosity of these thermoplastic polyester resins is suitably 0.55 or more, preferably 0.65 to 1.4.
It is. If the intrinsic viscosity is less than 0.55, it is difficult to obtain a multilayer balisong in a transparent amorphous state.
The resulting container also has insufficient mechanical strength.

Examples of the resin B used in the present invention, that is, the thermoplastic adhesive resin, include modified polyolefin resins, α-olefin-vinyl ester copolymers, copolymerized polyamide resins, copolymerized polyester resins, polyurethane resins, and ionomer resins. These may be used alone or as a mixture of two or more or as a mixture with other thermoplastic resins.

Examples of the resin C used in the present invention, that is, a thermoplastic gas barrier resin, include MX nylon, saponified ethylene-vinyl acetate copolymer resin, polyacrylonitrile copolymer resin, polyvinylidene chloride resin, etc. Among them, MX nylon is preferred.

Such MX nylon is metaxylylene diamine alone, or mixed xylylene diamine containing metaxylylene diamine and para-xylylene diamine in an amount of 30% or less of the total amount, and α/ω-carbon atoms of 6 to 10.
It means a polymer containing at least 70 mol% of structural units obtained from aliphatic dicarboxylic acids.

Examples of these polymers include homopolymers such as polymethaxylylene adipamide, polymethaxylylene sepacamide, polymethaxylylene speramide, etc., metaxylylene/paraxylylene adipamide copolymers, metaxylylene/ Copolymers such as paraxylylene pimeramide copolymer, metaxylylene/paraxylylene azelamide copolymer, and components of these alone or copolymers, and aliphatic diamines such as hexamethylene diamine, piperazine. Alicyclic diamines such as para-bis-
Aromatic diamines such as (2-aminoethyl)benzene, aromatic dicarboxylic acids such as terephthalic acid, lactams such as ε-caprolactam, ω-
Examples include copolymerization with ω-aminocarboxylic acids such as aminoheptanoic acid, aromatic aminocarboxylic acids such as para-aminobenzoic acid, and the like.

Further, these polymers may contain polymers such as nylon 6, nylon 6.6, nylon 6.10, and nylon 11.

The relative viscosity of these MX nylons is suitably 1.5 or more, preferably 2.0 to 4.0.

In the present invention, if necessary, one or both of resin A and resin B may contain a colorant, an ultraviolet absorber,
Antistatic agents, antioxidants, lubricants, nucleating agents, etc. can be added within the range that does not impair the purpose of the present invention.

Function and Effects of the Invention Biaxial stretching in which the multilayer parison obtained by the method of the present invention is heated to a stretching temperature and then expanded by a stretching rod that moves in the axial direction in a blow mold and by blowing pressurized gas. The multilayer container obtained by blow molding has an adhesive layer that does not impair gas barrier properties, transparency, or mechanical strength, and the outer layer and the center layer are firmly bonded to each other. There is no risk of layer delamination.

Incidentally, the stretching temperature in this case may be approximately the same as the stretching temperature of a parison made of a single thermoplastic polyester resin, and is preferably in the range of 70 to 130°C. The stretching is preferably carried out by 1 to 4 times in the axial direction, 2 to 7 times in the circumferential direction, and more preferably 5 to 15 times in area stretching ratio.

Example Hereinafter, it will be explained in more detail with reference to Examples.

Example Polyethylene terephthalate (hereinafter abbreviated as PET) with an intrinsic viscosity of 0.75 was used as resin A, and resin B
Modified polyethylene (manufactured by Mitsubishi Yuka Co., Ltd.,
Relative viscosity of resin C (product name "MODID E-310K") or modified polypropylene (manufactured by Mitsui Petrochemical Industries, Ltd., product name "ADMER GF550")
Using polymethaxylylene adipamide in 2.1,
It has an outer diameter of 30mmφ, a length of 120mm, and a wall thickness of 4mm, and the body has a five-layer structure in which two adhesive layers made of resin B are formed between two outer layers made of resin A and a center layer made of resin C. A multilayer parison consisting of 3
-Molded using a cylinder type injection molding machine.

The injection conditions are as follows: Cylinder temperature: Resin A side 275℃ Resin C side 265℃ Mold temperature: 20℃ Injection holding time: 10sec Cooling time: 15sec Injection volume ratio: Resin A 65% by volume Resin B 5% by volume Resin C 30% by volume Injection speed: Resin A 22c.c./sec Resin B 8c.c./sec Resin C 11c.c./sec The obtained parison was molded using a biaxial stretch blow molding machine. After heating the parison with a quartz heater until the surface temperature reaches 95°C, it is transferred into a blowing mold, and the drawing rod is heated at a transfer speed of 20cm/sec and a drawing blowing pressure of 20°C.
Biaxial stretch blow molding under Kg/ ^cm2 condition, full length
A bottle-shaped hollow multilayer container with a diameter of 275 mm, an outer diameter of 80 mmφ, and an internal volume of 1000 ml was obtained.

The obtained multilayer container had excellent gas barrier properties, transparency, and mechanical strength, and did not cause layer peeling.

In other words, the oxygen permeability was measured at 20°C and 65% relative humidity using a testing machine "OXTRAN 100" manufactured by Modern Control Co., Ltd., and was approximately 1/5 that of a single-layer polyethylene terephthalate container. The peel strength between Resin C and Resin B was measured in a 180-degree tensile direction on a 1-inch wide strip using a testing machine "Tensilon" manufactured by Toyo Baudouin Co., Ltd. When modified polyethylene was used as Resin B. 300～
500g/in, when using modified polypropylene
It was 200 to 400 g/in.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of an apparatus for implementing the method of the present invention, in which 1, 2, and 3 are injection cylinders for injecting resin A, resin B, and resin C, respectively, and 4 is an injection cylinder for injecting resin A, resin B, and resin C, respectively. Hot runner, 5 is gate,
6 represents a mold, and 7 represents a cavity. 2 to 5 are cross-sectional views showing step by step the conditions inside the cavity when carrying out the present invention, and 8, 9, and 10 represent resin A, resin B, and resin C, respectively. represents.

Claims (1)

[Claims] 1. Thermoplastic polyester resin, polyolefin resin, polycarbonate, polyacrylonitrile, polyvinyl chloride or polystyrene (resin A),
Using a molding machine with three injection cylinders for each of thermoplastic adhesive resin (Resin B) and thermoplastic gas barrier resin (Resin C), one mold clamping operation is performed on a single mold. Then, molten resin A, resin B, and resin C are continuously and sequentially injected in the order of resin A, resin B, and resin C. Finally, resin A is post-injected to cover the gate portion of the parison with resin A. The body part has a five-layer structure in which two adhesive layers made of resin B are formed between two outer layers made of resin A and a central layer made of resin C, and at least the mouth Method 2 of manufacturing a multilayer parison in which the opening part has a single structure Resin A is a thermoplastic polyester resin,
The method for producing a multilayer parison according to claim 1, wherein the resin C is a meta-xylene group-containing polyamide resin.