JPS60125667A - Multilayer plastic vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multilayer plastic container, more specifically, it is composed of a laminate of an olefin resin layer and an oxygen barrier layer of ethylene-vinyl alcohol copolymer, and the adhesive strength between the two resin layers is This invention relates to a multilayer plastic container with significantly improved properties.

Laminated with an adhesive resin layer consisting of an olefin resin such as polypropylene or polyethylene that has excellent moisture resistance, and an ethylene-vinyl alcohol copolymer that has excellent oxygen barrier properties, and an acid or acid anhydride modified olefin resin. BACKGROUND OF THE INVENTION Laminated bodies are widely used in various fields as containers with excellent content preservation properties in the form of bottles, cups, pouches, etc.

It is desirable for these multilayer plastics to increase the adhesive strength between each layer in order to improve impact resistance.

However, conventional laminates using the above-mentioned acid or acid anhydride-modified olefin resin as an adhesive layer are not always satisfactory because the adhesive strength between each layer decreases depending on the contents. .

An object of the present invention is to bond a layer made of an olefin resin and a layer made of an ethylene-vinyl alcohol copolymer via an acid- or acid anhydride-modified linear low-density polyethylene-containing layer, and to have excellent delamination resistance. We offer multi-layer plastic containers.

Another object of the present invention is to provide a multilayer blow-molded container in which each resin layer exhibits excellent delamination resistance regardless of the type of contents.

According to the present invention, at least one layer mainly composed of an olefin resin; at least one oxygen barrier layer mainly composed of an ethylene-vinyl alcohol copolymer having an ethylene content of 25 to 60 moles; A multilayer plastic container is provided which is characterized in that it is made up of a single stack of adhesive resin layers containing acid- or acid anhydride-modified linear low-density polyethylene interposed between both phase resin layers.

The present invention is characterized in that an acid- or acid-anhydride-modified resin based on IJ near (linear) low-density polyethylene is selectively used as the adhesive resin layer among various acid- or acid-anhydride-modified olefin resins. It is something that you have.

Linear low-density polyethylene, which is the base of the acid- or acid anhydride-modified resin, has several characteristics that are not found in commonly used high-pressure low-density polyethylene and low-pressure high-density polyethylene.

That is, high-pressure low-density polyethylene has a molecular structure with long chain branches and is a single polymer of ethylene, whereas linear low-density polyethylene has a substantially straight-chain molecular structure and consists of ethylene and carbon. It consists of a copolymer with 4 to 8 α-olefins. On the other hand, low pressure high density polyethylene has a density (25°C) of 0.940 to 0.9659/cm.
3, and its molecular structure has almost no short branched chains, whereas linear low-density polyethylene has a density in the range of 0.915 to 0.9359/GnL'', It is different in that it has a short branched chain derived from the above-mentioned α-olefin.

Comonomers in this linear low density polyethylene include butene-1, pentene-1,4-methylpentene-
1, hexene-1,2-methyl-butene-1, octene-1, and other α-olefins having 4 to 8 carbon atoms;
It is incorporated into the polymer chain at a concentration of 6% to 15%, especially from 6 to 15 times Jt.

This linear low-density polyethylene (L-LDPE) is also related to the above-mentioned chemical structure and can be used with other olefin resins, such as high-pressure low-density polyethylene (CHpLl)PE),
Compared to high density polyethylene (HDPE), crystalline propylene ethylene copolymer (PPE), etc., it has different physical properties as shown in Table A below.

L LDPE 850 300 106~122HP
LDPE 600 120 94~114HDPE 8
00 230 118-166PPE 800 330
125-156 From Table A above, it is clear that the linear low-density polyethylene, which is the base of the modified resin, has the characteristics of having a low melting point while having high elongation and strength.

The modified resin used in the present invention can be easily obtained by graft-modifying the above-mentioned linear low-density polyethylene with an ethylenically unsaturated carboxylic 5-acid or its anhydride. Ethylenically unsaturated carboxylic acids or their anhydrides include maleic anhydride, maleic acid, fumaric acid,
Acrylic acid, methacrylic acid, crotonic acid, itaconic acid,
Mention may be made of citraconic acid, hegisahydrophthalic anhydride, etc., which may be contained in a concentration of 1 to 600 millimeters of equivalene/1oo, p-polymer, based on the final resin.

The adhesive layer used in the present invention can be made of acid-modified linear low-density polyethylene alone, or can be made of a blend of acid-modified linear low-density polyethylene and unmodified linear low-density polyethylene. In the latter case, the blending ratio of both can be freely changed as long as the overall carbonyl group hardness is within the above range. Furthermore,
This adhesive layer has a linear low density polyethylene content of 5
0 weight or more, and as long as the overall carbonyl group concentration is within the above-mentioned range, other olefin resins, such as acid-modified or unmodified crystalline polypropylene,
High-density polyethylene, high-pressure low-density polyethylene, crystalline ethylene-propylene copolymer, etc. may be contained in the form of a blend.

According to the present invention, by using an adhesive layer mainly composed of acid or acid anhydride modified linear low density polyethylene,
The peel strength of a polyolefin/ethylene vinyl alcohol copolymer laminate, especially after the contents have been stored, can be significantly improved compared to conventional acid- or acid anhydride-modified olefin resins.

In general, in this type of laminated structure, there is almost no peeling between the olefin resin layer and the adhesive resin layer, and i Adhesive 1M
It is observed that peeling occurs between the fat M and the ethylene-vinyl alcohol copolymer layer.

Table 3 below shows that the carbonyl group concentration is 30 wag/I
The figure shows the peel strength (kg/15 m width) of a laminated sheet of DOI polymer maleic anhydride-modified olefin resin and 40 mole ethylene-vinyl alcohol copolymer containing ethylene.

Filled with Calan as the smoke content, 30'C, 80% l?
Stored in M for 3 weeks.

The above results demonstrate that the acid- or anhydride-modified linear low-density polyethylene of the present invention has superior resistance compared to conventional acid- or acid-anhydride-modified olefin resins such as modified low-density polyethylene, modified high-density polyethylene, and modified polypropylene. It can be seen that it has delamination properties.

In the present invention, by using acid or acid anhydride-modified linear low-density polyethylene as the adhesive resin layer, it is possible to obtain superior interlayer adhesive strength and impact resistance compared to conventional modified olefin resins. This is thought to be due to the fact that modified linear low-density polyethylene has the property of being able to stretch well under relatively low tension.

The above results demonstrate that the resin based on linear low-density polyethylene has the property of being able to stretch well under relatively low tension, and due to this property, the laminated container of the present invention is free from destruction of the adhesive interface and distortion of the adhesive interface. It is recognized that this prevents the residue from remaining and maintains excellent adhesive strength. Furthermore, the fact that the adhesive resin itself has excellent mechanical strength under normal conditions is also considered to be helpful in increasing adhesive strength. It should be understood that acid modification within the range described above causes almost no change in the physical properties of the resin.

In addition to the acid or acid-modified base resins mentioned above, such as low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and linear low-density polyethylene, the layer mainly composed of olefin resin may include ethylene-vinyl acetate. Contains a copolymer etc. as a main component,
In addition, those containing small amounts of resins constituting the oxygen barrier layer and the adhesive layer may also be used. In this way, it is possible to use Paris, etc., which is produced as a by-product during blow molding, as the olefin resin layer or a part thereof.

In addition, as the ethylene-vinyl alcohol copolymer constituting the multilayer container, from the viewpoint of oxygen barrier properties, an ethylene-vinyl acetate copolymer having an ethylene content of 25 to 60 moles, a saponification degree of 96 moles or more, In particular, a copolymer obtained by saponification to a molecular weight of 99% or more can be preferably used. Of course, this oxygen barrier layer may contain other thermoplastic resins as long as the essence of the ethylene-vinyl alcohol copolymer is not impaired.

In the present invention, the above-mentioned olefin resin layer (73),
The oxygen barrier layer (A) and the adhesive layer (C) are the layers (
Any layer arrangement can be used as long as C) is interposed between layer CA) and layer (B), for example (i)
A/C/B three-layer configuration, 10- (II) CIA/C/B four-layer configuration, (iii) B/C/A/C/B, B/C/A/C/B
'.

(B+A+C)/C/A/C/(B0A+C) five-layer structure, (1v) six-layer structure IB'/C/A/C/B (7) B/(B+A+C)/C/A/ C/11 (8) (I
Upper layer composition/(B+A+CVC/A/C/CB+A+C) IB
(9) B/'B'/C/A/C/B'/B [o]
It can take any layer configuration such as.

The thickness of each layer is also not particularly limited, and generally B:A21:
It is preferable to provide each layer with a thickness ratio of 1 to 500:IB:C21=1 to 500:1.

According to the present invention, the above parison or sheet having a multilayer structure is formed by simultaneous melt extrusion, and then the parison or sheet is shaped into a bottle shape, a cup shape, an ant shape, etc. by a plastic processing method known per se. Form into a container.

The multilayer parison is manufactured by simultaneous melt extrusion or simultaneous injection molding of the resin layers described above into multiple layers, and a blow molded container is obtained by expanding the parison in a molten state with a fluid.

The molded container according to the present invention is generally manufactured with a basis weight (volume per unit g of resin) of 0.01 to 5 de/g, particularly 0.05 to 21e7 g, although it differs depending on its use. The thickness of is 0. U2 to 1■, especially 0.
The desired combination of gas barrier properties, stiffness, and transparency can be achieved within these ranges.

The container according to the present invention is useful as a container for preserving contents as is, and is useful for storing liquid or pasty foods and drinks,
For example, alcoholic beverages including sparkling wine such as beer, fruit liquors such as sake, whiskey, shochu, and grape wine, and various cocktails such as gin fizz; various carbonated beverages including cola, cider, plain soda, etc.; lemon juice, orange juice Fruit juice drinks, including straight juices such as flamm juice, grape juice, and strawberry juice, or processed fruit juice drinks such as nectar; Cannabis juice drinks, including tomato juice and various vegetable juices; Sugars such as sugar or fructose, citric acid, and coloring. Synthetic drinks and vitamin-enriched drinks containing synthetic juices using agents, fragrances, etc., or adding vitamins as necessary; Lactic acid bacteria drinks; Stews such as cooked curry, cooked hash, borscht, and beef stew;
Brevies such as meat sauces; boiled vegetables, fish and meat such as sweet and sour pork, sukiyaki, fried vegetables, Chinese stew, asparagus stew, beans, cream-simmered tuna; consommé soup, potage soup, miso soup, pork soup, Soup such as Kenchin soup; rice food such as rice, sekihan, grilled rice, gomoku rice, pilaf, crab; spaghetti, soba, radon, Chinese soba,
Meals like macaroni 44; Complex seasonings for fried rice and soup or Chinese buckwheat and soup; Favorite foods such as red bean, red bean, shiruko, apricot, honey bean, pudding, jelly, water yokan, etc.; meatballs, hamburger steak, corned beef, ham , processed seafood and livestock products such as sausage, grilled fish, kunsei, bean curd, kamaboko; tangerine,
Fruit products such as peaches, pineapple, cherries, and olives; seasonings such as pepper oil, sauce, vinegar, mirin, dressing, mayonnaise, ketchup, edible oil, miso, lard, and ketchup; tofu, jam, butter, margarine, etc. Luxury goods: Liquid medicines such as Ringer's solution, concentrated medicines, cosmetics, perfumes, detergents; Also, ketones such as acetone and methyl ethyl ketone; fatty hydrocarbons such as n-hexane and n-heptane; fatty acids such as cyclohexane Hydrocarbons; aromatic hydrocarbons such as benzene, toluene, and xylene; chlorine-containing compounds such as tetrachloroethane and tetrachlorethylene; or various higher fatty acids; gasoline, kerosene, petroleum, benzine, m-oil, thinner, fleece, and silicone oil , light oil, machine oil; or liquefied freon (trade name of DuPont, USA), etc.
It has little waste and is useful as a container for storing each of the above-mentioned contents.

The invention is illustrated by the following example.

14- Example 1 Melt index is 0.59/10 min, density is 0.9189/cb, DTA method (heating rate, 10°C
The inner and outer layers are made of low-density polyethylene with a peak melting point of 110°C according to the above method, and the oxygen barrier resin layer (intermediate layer) has an ethylene content of 60 mol, a vinyl alcohol content of 70 mol, and a melting point of 110 ℃ according to the above method. It is made of ethylene-vinyl alcohol copolymer at 182°C and has a grease-resistant adhesive layer (1) Melt index (Ml
) is 0.4 g710min, density is 0.93 g/c
c, also has a melting point of 122°C and a carbonyl group concentration of 6
Modified linear low density polyethylene with 0 mmol/100 g polymer.

(11) A mixture of the modified linear low density polyethylene and unmodified linear low density polyethylene in a mixing ratio of 90:10 (weight ratio).

Outer layer/adhesive layer/middle layer/adhesive I
@ / A bottle with a 5-layer structure consisting of an inner layer with a diameter of 40 mm, an effective length of 880 m, 1 melt channel (for the middle layer), a diameter of 40 mm, an effective length of 880 m, and 2 melt channels. The flow path (for the adhesive layer) has a diameter of 65 mm and an effective length of 1430 mm.

A multilayer parison with a 5-layer structure was molded using an extruder group having a valley dimension with two melt channels (for inner and outer layers) and a 5-layer die for coextrusion.

The composition ratio of each layer of these parisons is all outside! -Knee i-: 1, and the total wall thickness is approximately 5 torso, 5 20
0 Inner diameter is 30yxI11. The length was 301 nm. Below, parison f using (1) as adhesive layer resin
A, the parison using the same hammering is designated as B.

This multilayer parison was sandwiched between blow molds in a molten state, and air was blown from one end to expand the parison, followed by blow molding to obtain blow bottles AB and BB having a five-layer structure. The resulting bottle has an inner diameter of 100 mm, a height of 150 mm, an average wall thickness of 0.6 rtan, and an internal volume of approximately 100 mm.
The bottle had a basis weight of about 0.31 dl19 and was cylindrical.

The oxygen permeability of these bottles (QO2) vj Kosho 52
Measured by the method described in Publication No.-11263, and further,
Fill 20 bottles AB and BB with 1000 cc of water, drop the bottles from a height of 120 IIJ to the concrete floor at room temperature, and remove the bottom, part of the bottom corner, body, shoulder, mouth, etc. of each bottle. The presence or absence of delamination occurring in a portion was visually observed by a panel of five people, and the delamination resistance was examined.

For comparison, a bottle CB similar to the one described above was prepared using low density polyethylene with a carbonyl group concentration of 30 mmol/l0JI polymer and a melting point of 110°C as the adhesive resin.
I molded it.

Table 1 shows the evaluation results for these bottles. The oxygen permeability is the same for bottles AB, HB, and CB, but the resistance to delamination is higher for bottle A than for bottle CB.
It can be seen that it is very excellent in B and BB.

17- Table 1 Patent applicant: Toyo Seikan Co., Ltd. 18-

Claims (1)

[Claims] (1) At least one layer mainly composed of olefin resin;
an oxygen barrier layer; and an acid containing an acid having a density of 0.915 to 0.965177 cm and a concentration of 1 to 600 mm equivalent/100.@polymer interposed between these two phase resin layers. A multilayer plastic container comprising a laminate of adhesive resin layers containing anhydride-modified linear low-density polyethylene.