JPS5968351A - Polyethylene resin composition and laminate thereof - Google Patents

Abstract

PURPOSE:To provide a polyethylene resin compsn. having excellent adhesion and environmental stress cracking resistance, consisting of a specified ethylene copolymer or medium/low density polyethylene and a specified modified ethylene copolymer or high-density polyethylene. CONSTITUTION:A compsn. consists of 99.9-45wt% ethylene copolymer composed of ethylene and 0.2-20mol% of an alpha-olefin (other than ethylene) or medium/ low density polyethylene and 0.1-55wt% ethylene copolymer obtd. by modifying the above ethylene copolymer with an unsaturated carboxylic acid or its derivative, or high-density polyethylene. This compsn. (layer A) is laminated to a resin (layer B) selected from a saponified product of an ethylene/vinyl acetate copolymer, polyamide, polyester and polyolefin to obtain a laminate. This laminate has improved peeling strength, gas barrier properties and resistance to oils and water and excellent thermoformability and environmental stress cracking resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ethylene resin composition and a laminate formed by laminating the composition and a resin such as a saponified ethylene-vinyl acetate copolymer.

Polyethylene has traditionally been widely used as packaging and containers for various foods and chemicals, as it has excellent properties such as transparency, flexibility, hygiene, and processability, and can be obtained at a relatively low cost. . However, polyethylene has some disadvantages such as high gas permeability, so it is not used alone as a material for packaging and containers, and other materials such as polyamide, saponified ethylene-vinyl acetate copolymer, etc. Laminates with molecular materials are being considered.

However, since polyethylene is a nonpolar material, it has almost no adhesive strength, and there are various problems when using it as a laminate.

In recent years, in order to improve these drawbacks, (1) methods of modifying polyethylene with unsaturated carboxylic acids or its anhydrides, and (2) methods of modifying polyethylene with other polymers, such as saponified ethylene-vinyl acetate copolymers, have been developed. , thermoplastic polyester, and polyvinyl alcohol/l/sudo have been proposed.
103480).

However, although the laminates obtained by these methods have sufficient initial adhesion, they have the disadvantage of poor durability and decreased adhesion over time. Furthermore, the environmental stress cracking resistance is not sufficient, making it difficult to apply it to chemical containers and steel pipes as anticorrosive coatings, which has placed significant limitations on its use.

The object of the present invention is to provide adhesive properties that eliminate the above-mentioned drawbacks.

An object of the present invention is to provide a polyethylene resin composition having excellent environmental stress cracking resistance and a laminate using the composition.

That is, the present invention first provides (a) ethylene and 0.
Ethylene copolymer or medium or low density polyethylene consisting of 2 to 20 mol% α-olefin (excluding ethylene) 7
99.9 to 45% by weight and (b) 0.1 to 55% by weight of the ethylene copolymer or high density polyethylene modified with an unsaturated carboxylic acid or a derivative thereof. , furthermore, the resin composition (A) and a saponified ethylene-vinyl acetate copolymer.

The present invention provides a laminate formed by laminating a resin selected from the group consisting of polyamide, polyester, and polyolefin.

The ethylene copolymer which is component (a) in the polyethylene resin composition of the present invention is composed of ethylene and 0.2 to 20 mol%, preferably 1 to 10 mol% of other α-olefin. be. If the amount of α-olefin is less than 0.2 mol% of the copolymer, durable adhesion and environmental stress cracking resistance will be insufficient, and if it exceeds 20 mol%, strength and other physical properties will decrease significantly. Therefore, it is not desirable.

Other α-ols/fins to be copolymerized with ethylene include those having 3 to 20 carbon atoms, preferably 4 to 20 carbon atoms.
8, specifically propylene, butene-1゜pentene-1, hexene-1,4-methylpentene-1, octene-1, nonene-1, etc., and one or two of these can be used. It is good to use the above in combination.

This ethylene copolymer is produced by ionic polymerization (gas phase polymerization, solution polymerization) under medium to low pressure, and has a density of 0.910 to 0.96017/cni, preferably 0.9], 5 ~0.930! i'/cn
l, melt index (M■) is (1,1~30f/
10 minutes, preferably 0.5 to 1247'/10 minutes.

That is, α- which essentially copolymerizes with ethylene.
It is an ethylene copolymer having short chain branches consisting only of olefin residues, and has recently come to be known as linear low- and medium-density polyethylene.

Therefore, it is essentially different from low-density polyethylene copolymers having long chain branches that have been conventionally obtained by high-pressure radical polymerization.

In the present invention, the above-mentioned ethylene copolymer or medium or low density polyethylene is used as component (a).

Here, low-density polyethylene refers to polyethylene with a density of 0.910 to 0.9409/cA conventionally obtained by a high-pressure method, and includes copolymers with other α-olefins.

On the other hand, as the component (b) of the present invention, the above-mentioned ethylene copolymer or high-density polyethylene modified with an unsaturated carbonic acid or a derivative thereof is used. Here, high-density polyethylene refers to a density of 0.940 to 0.970, which is conventionally obtained by a low-pressure method! i'/c
ni polyethylene, including copolymers with other α-olefins.3 Here, the unsaturated carboxylic acid is acrylic acid.

Methacrylic acid, maleic acid, fumaric acid, itaconic acid,
Crotonic acid, /traconoic acid, sorbic acid.

These include mesaconic acid and angelic acid. In addition, its derivatives include acid anhydrides, esters, and amides.

Imides, metal salts, etc., such as maleic anhydride,
Itaconic anhydride, citraconic anhydride, methyl acrylic acid, methyl methacrylate, ethyl acrylate, butyl acrylate, maleic acid monoethyl ester, acrylamide, maleic acid monoamide, maleimide, N-butylmaleimide, sodium acrylate, Can be used to store sodium methacrylate, etc.

The method for modifying the ethylene copolymer or high-density polyethylene with these unsaturated carboxylic acids or derivatives thereof is not particularly limited, and any known method may be used.

For example, the process proceeds by adding a radical initiator to ethylene copolymer or the like and maleic anhydride in the presence or absence of a solvent and heating the mixture. During the reaction, other vinyl monomers such as styrene or rubbers such as liquid rubber and thermoplastic rubber may also be present.

The content of unsaturated carboxylic acid or its derivative in the ethylene copolymer or high density polyethylene modified in this way is usually 0.001 to 15% by weight, preferably 0.005 to 10% by weight, and more preferably is 0.05~5
% by weight. This modified product does not necessarily have to be entirely modified, and may be a blend of unmodified polyethylene.

In the polyethylene resin composition of the present invention, either an ethylene copolymer, medium or low density polyethylene is used as the (a) component, and either a modified ethylene copolymer or a high density polyethylene is used as the (b) component. or Among these, combinations using an ethylene copolymer as component (a) are particularly preferred.

The blending ratio of component (a) and component (b) is 99.9 to 45% by weight of component (a), preferably 99 to 65% by weight, and more preferably 98 to 80% by weight. , 0.1 to 55% by weight, preferably 1 to 35% by weight of component (b),
More preferably, it is 2 to 20% by weight.

The polyethylene resin composition of the present invention having the above structure is as follows:
It has extremely good adhesion to other resins, and
Its adhesive strength does not deteriorate even when exposed to heat, water, salt water, etc., and it has excellent environmental stress cracking resistance. Therefore, this resin composition exhibits excellent properties when forming a laminate with other resins or creating a blend with other resins. In addition to the above-mentioned components, the resin composition of the present invention may optionally contain compatible combs.

Ethylene-01 vinyl triate copolymer and the like can also be added. The rubber is preferably an ethylene-propylene comb such as ethylene-propylene copolymer or ethylene-propylene/enterpolymer, and the above resin composition 1
00 parts by weight or less, preferably 3 to 1 parts by weight
It is effective to mix within the range of 5 parts by weight. It goes without saying that various additives such as antioxidants and ultraviolet absorbers can be added as appropriate.

Next, the second invention, a laminate, will be explained.

As mentioned above, the second invention is a laminate formed by laminating the above-mentioned polyethylene resin composition ([A] layer) and a specific monthly charge ([89 layers)]. [89] As the material constituting the layer, saponified ethylene-hinyl acetate copolymer, polyamide, polyester, or polyolefin is used. Although the composition of the saponified ethylene-vinyl acetate copolymer is not particularly limited, it is preferable to use an ethylene-vinyl acetate copolymer having an ethylene content of 25 to 50 mol %, with a saponification degree of 93%. % or more, preferably 96
It is preferable to use a product obtained by saponifying the product so that the content is 3% or more; if it is outside this range, it is not preferable because it will have inferior casing properties and oil resistance.

Polyamide is a linear synthetic polymer with acid amide bonds obtained by condensation of diamide/7-carphonic acid, self-condensation of amino acids, and ring-opening polymerization of lactam. 6,6-nylon (polyhexamethyleneateifamito); 6,
10-Nylon (Polyhexamethylene)
; 11-nylon (polyundecamide); 12-nylon, etc. can be used.

Next, examples of polyester include polyethylene terephthalate and polybutylene terephthalate. Also,
There are various types of polyolefins, such as high-density polyethylene, low-density polyethylene, linear polyethylene,
Medium density polyethylene.

Polypropylene or a copolymer thereof can be used.

The laminate of the present invention has a polyethylene resin composition layer ([A3
layer) and a layer such as a saponified ethylene-vinyl acetate copolymer ([This is a two-layer laminate with 89 layers, but if necessary, A-B-A, B-A-B, polyolefin-A −
A multilayer laminate such as B, polyolefin-A-B-A-polyolefin may also be used.

The laminate of the present invention can be obtained by applying known means such as thermocompression bonding, in-die lamination, die-out lamination, etc. to obtain the desired sorting and film, and then blow molded products by blow molding. can be done.

The laminate of the present invention thus obtained has interlayer adhesion (
The peel strength has been significantly improved, and the gas barrier
Properties such as hardness, oil resistance, and water resistance have also been improved, and it is said to have good thermoformability and excellent environmental stress cracking resistance! He has a Buddhist statue. This laminate can be used as a material for packaging or containers for various foods, beverages, chemicals, etc., and can also be effectively used as a coating material for steel pipes for various purposes.

Next, Example 1 of the present invention will be shown. Example (1) Hm of modified polyethylene A Low density ethylene copolymer (M I 26 f / I
0 min, density 0.92 W/cra, butene-1 content 2.1% by weight) 100 parts by weight, maleic anhydride 10
Parts by weight and 0.5 parts by weight of didimyl peroxite were added to 600 parts by weight of Kinolev, dissolved by heating, and heated at 125°C for 2 hours.
The reaction was allowed to take place while stirring for a period of time. Next, the reaction product was poured into a large amount of acetone, and the reaction product was separated by precipitation and dried to obtain maleic anhydride-modified polyethylene A. The maleic anhydride content of the obtained modified polyethylene was 3.0% by weight.
The air flow rate was 9 fl/10 min.

(2) Raw material for producing modified polyethylene B Polyethylene, M113f/10 minutes, density 0
．． Modified polyethylene/B was obtained by carrying out the same operation as in (1) above except that high-density polyethylene of 95 fl/cni was used. 9JA image density polyethylene (MI23) of the obtained modified poly(3) modified polyethylene C
2/10 minutes.

Modified polyethylene C was obtained by performing the same operation as in (1) above using polyethylene (density: 0.90 Y/cni). The maleic anhydride content of the obtained modified polyethylene was 3.1
It was % by weight, and the weight was 8fl10 minutes.

(4) Production of resin composition and laminate The formulations shown in Table 1 were kneaded and extruded at 200°C to obtain pellets. The pellets were coextruded with saponified ethylene-vinyl acetate copolymer, 6-nylon, polyethylene terephthalate, and polyolefin, each layer having a thickness of 200 mm.
A bilayer sheet of μ was produced. The molding temperature is 220°C for the resin composition/saponified ethylene-vinyl acetate copolymer.
, 240°C for resin composition/6-nylon, 260°C for resin composition/polyethylene terephthalate,
In the case of resin composition/polyolefin, the temperature is 200°C.
The withdrawal speed was 5 ++z 7 minutes. The results of 180° peel strength are shown in Tables 1 and 2.

Table 1 Table 1 (continued) I L L I) P E Low enrichment ethylene copolymer (N+ I 2 ? /10 min, density 0.926 ?
/orI, spot/-1 content 17w [%] rice 2 LDPE: low grade polyethylene (I~41o,
8? /10 minutes, density 0.924 f? /crrt
) Rice 3 EVA saponified product: Saponified ethylene-vinyl acetate copolymer (vinyl acetate content 40 wt%, saponification degree 9
8%) Cap 46-Nylon: Relative viscosity 44 45 pbT: Polyethylene terephthalate Relative viscosity 11 Vermillion 6 HDPE: High density polyethylene (M work 09 g/10 min.

Density: 0.9547.10 rI ) Rice 7180° Peel strength ° Tensile speed: 50 mm/min
2 table

Claims (2)

[Claims] (1) (a) Ethylene and 0.2 to 20 mol% a-
Ethylene copolymer consisting of olefin (excluding ethylene) or medium or low density polyethylene 99.9 to 45% by weight
and (b) a polyethylene resin composition comprising 0.1 to 55% by weight of the ethylene copolymer or high density polyethylene modified with an unsaturated carboxylic acid or a derivative thereof. (2) (A) (a>-'n tyrene and 0.2-2
Ethylene copolymer consisting of 0 mol% α-olefin (excluding ethylene) or medium or low density polyethylene 99.
(b) 1 to 55% by weight of the above-mentioned ethylene copolymer or high-density polyethylene modified with an unsaturated carboxylic acid or a derivative thereof; and CB) an ethylene-vinyl acetate copolymer. Combined saponified matter. A laminate made of a resin selected from the group consisting of polyamide, polyester, and polyolefin.