JPS6047106B2 - multilayer hollow container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a container suitable for storing agricultural chemicals, industrial chemicals, liquid pharmaceuticals, and the like.

In recent years, agricultural chemicals, fuel oil, industrial chemicals (aromatic hydrocarbon type, aliphatic hydrocarbon type), etc. have been replaced with conventional metal cans and glass bottles by multilayer hollow containers with inner layers made of polyamide or saponified ethylene-vinyl acetate copolymer. It is being stored in a container.

However, such multilayer hollow containers do not have excellent resistance to all liquids; for example, polyamides are susceptible to phenols, alcohols, acids, etc., and saponified ethylene/vinyl acetate copolymers are sensitive to polyamides. Similarly, it had the disadvantage of not having sufficient resistance to solvents having hydroxyl groups. Furthermore, metals are unsuitable for acids, and glass is unsuitable for alkaline hydrates. On the other hand, fluororesins that have fluorine atoms in their polymer molecules show excellent resistance to all chemicals.

Fluororesin was originally developed as a corrosion-resistant and chemical-resistant material, and is the best among synthetic resins in terms of non-water absorption, abrasion resistance, non-adhesiveness, self-lubricating properties, heat resistance, cold resistance, weather resistance, etc. ing. Among these fluororesins, one that has the best chemical resistance is tetrafluoroethylene (hereinafter abbreviated as PTFE), which is completely fluorinated and is composed of only fluorine and carbon.

PTFE has a structure in which a carbon chain is closely surrounded by fluorine atoms, and its C-F bonding strength is extremely strong.
Excellent heat resistance, chemical resistance, and oxidation resistance. Due to the repulsion between highly charged fluorine atoms, the intermolecular cohesive force is small. Therefore, in order for a PTFE molded product to have practical strength, the PTFE molecular chains must be long enough to form a bond with each other, i.e. , the molecular weight must be significantly higher than that of ordinary plastics. Therefore, the melt viscosity is 380
It has a poise of 1~■° at ℃, and although it is a thermoplastic resin, it has poor thermoplasticity and cannot be molded using methods such as extrusion molding or injection molding that are applied to ordinary plastics, so it is molded using a method similar to powder metallurgy. be done. Fluororesins include ethylene-tetrafluoroethylene alternating copolymer resin (hereinafter referred to as ETFE), which is thermoplastic and can be extruded, vinyl fluoride resin (PVdF), vinyl fluoride resin (PVF), ethylene-tetrafluoroethylene Chloride trifluoride ethylene alternating copolymer resin (ECTFE), trifluorochloride ethylene resin (PCTFE), tetrafluoroethylene-hexafluoroethylene alternating copolymer resin (FEP), tetrafluoroethylene/perfluoroalkoxyethylene resin Polymer resin i (PFA) and the like exist, and since these contain fluorine in their molecular segments, they exhibit performance close to that of PTFE. However, although fluororesins have excellent performance, they are very expensive, so their applications are restricted from a cost perspective, and they are only used in special fields.

Fluororesins generally have a large permeability coefficient for gases such as oxygen, nitrogen, and carbon dioxide, so they are not suitable for storing contents that are susceptible to oxidative deterioration. Furthermore, due to the non-adhesive property that is a characteristic of fluororesin, it has been difficult to adhere it to other resins. Therefore, the present invention eliminates the drawbacks in view of the above points,
The purpose of the present invention is to economically provide a container having excellent chemical resistance, moisture proofing properties, gas barrier properties, and interlayer adhesion properties by using a multilayer coextrusion blow molding method.

The present invention will be explained in detail below. That is, the present invention has a multilayer structure in which the inner layer is a thermoplastic fluororesin, the middle layer is a polyolefin having an epoxy group in its molecule by copolymerization with unsaturated glycidyl, and the outer layer is a polyamide or a saponified ethylene-vinyl acetate copolymer. Relating to hollow containers.

As the fluororesin used in the present invention, ETFE. ．． PVdF. ．． PVFNECTFE,. PC
TFE,. There are FEP, etc., but from the viewpoint of moldability, ET
FE. ．． PVclF and FEP are preferred.

Polyamides include condensation of diamine and dicarboxylic acid,
Linear polymers with acid amide bonds obtained by condensation of amino acids and ring opening of lactams, such as nylon 6, nylon 6, nylon 610, nylon 11, nylon 1
2 and copolymerized nylon 6-6 can be used.

Although the chemical composition of the saponified ethylene-vinyl acetate copolymer is not limited, G. Considering the barrier properties, oil resistance, and water vapor permeability, the ethylene content is 25%.
It is preferable to use one obtained by saponifying 50 mol% of ethylene-vinyl acetate copolymer so that the degree of saponification becomes 93% or more, preferably 96% or more.

The crystalline polyolefin modified by copolymerization with unsaturated glycidyl used in the intermediate layer of the present invention has an epoxy group in its molecule, and has a fluororesin in the inner layer and a polyamide, ethylene, or vinyl acetate in the outer layer. It is possible to firmly adhere the saponified copolymer.

Here, unsaturated glycidyl refers to glycidyl methacrylate, glycidyl acrylate, etc., and its structural formula is as follows.

Glycidyl methacrylate Niglycidyl acrylate The polyolefin used in the present invention includes not only homopolymers of α-olefins such as ethylene and propylene, but also copolymers of ethylene and other α-olefins, such as ethylene-propylene copolymers. Polymer, ethylene-butene-1
Copolymers and ethylene-hexene-1 copolymers also include crystalline polymers of α-olefins such as propylene-butene-1.

These polymers and copolymers may be used as a blend. As a method for modifying polyolefin, it can be obtained by copolymerizing the above-mentioned unsaturated glycidyl and polyolefin. Copolymerization methods include melt-kneading the polyolefin, polymerization monomer, and catalyst in an extruder, or adding the polymerization monomer and catalyst to the polyolefin suspended in an appropriate solvent, followed by heating and stirring. There are methods etc. This three-layer hollow container can be formed by conventional multilayer extrusion blow molding.

Conventional fluororesin single-layer containers are extremely expensive and have not been applied in special physical and chemical fields or medical fields, but this method can be made at a lower cost than before without losing the performance of the fluororesin. A container with excellent chemical resistance and gas barrier properties can be provided, making it possible to apply it to pharmaceutical containers. Examples and comparative examples of the present invention are shown below. Example 1 The inner layer was made of ethylene-tetrafluoroethylene alternating copolymer resin (PETFE) having a melting point of 270°C and a melt viscosity of 101 to 1 Cf' poise in the temperature range of 300 to 330°C, and the middle layer had a density of 0. 94 MI 1.8 ethylene/vinyl acetate/glycidyl methacrylate terpolymer, outer layer with relative viscosity 4. ＼Using 6-nylon with a melting point of 224°C, the weight of the three-layer structure was 45y1 using a multilayer coextrusion blow molding machine.
A container with an internal capacity of 500 mt was molded.

At this time, the wall thickness ratio was inner/middle/outer = 2/6/2. <
Example 2> The same resin as in Example 1 was used for the inner layer and intermediate layer,
The outer layer has a melting point of 184°C Mll. 5 (190℃2460V)
A multilayer container with a weight of 45 Da and an internal capacity of 500 m1 was molded using the saponified ethylene/vinyl acetate copolymer.

The wall thickness ratio is inner/middle/outer = 2/6/2.Comparative Example 1〉 The inner layer and the middle layer are hard.The same resin as in Example 1〉 is used,
A multilayer container with a weight of 45y1 and an internal capacity of 500mL was molded using high-density polyethylene with a density of 0.95MI0.3 for the outer layer.

Wall thickness ratio is inner/middle/outer = 2/1/7 (Comparative example 2) 6 for inner layer
- A bolt similar to Example 1 was molded using nylon, maleic anhydride-modified polyethylene for the intermediate layer, and high-density polyethylene with a density of 0.95M10.3 for the outer layer. Wall thickness ratio is inner/middle/outer = 2/1/<Comparative Example 3> Density 0.95M
■Example 1 of 0.3 high-density polyethylene single-layer container
It was molded in the same way.

Next, the chemical resistance of Examples 1 and 2 and Comparative Examples 1, 2, and 3,
A table comparing gas barrier properties is shown.

Claims (1)

[Claims] 1 A multilayer hollow vessel in which the inner layer is a thermoplastic fluororesin, the middle layer is a crystalline polyolefin that has an epoxy group in its molecule by copolymerization with unsaturated glycidyl, and the outer layer is made of polyamide or saponified ethylene-vinyl acetate copolymer. .