JPH0146313B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminate of a polyolefin resin composition. Polyolefins have traditionally been used in a wide range of packaging and containers for various foods and chemicals, as they have excellent properties such as transparency, flexibility, hygiene, and processability, and can be obtained at relatively low prices. . However, polyolefins have drawbacks such as high gas permeability, so they cannot be used alone as materials for packaging or containers, and can be used with other materials, such as polymeric materials such as polyamides and saponified ethylene-vinyl acetate copolymers. It is used as a laminate with metals such as aluminum and aluminum. However, since polyolefin 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, methods have been developed to (1) modify polyolefins with unsaturated carboxylic acids or their anhydrides, and (2) add other polymers to modified polyolefins, such as saponified ethylene-vinyl acetate copolymers. , thermoplastic polyester, polyvinyl alcohol, etc. have been proposed (Japanese Patent Application Laid-Open No. 53-39381, JP-A No. 52-124080).
(Japanese Patent Application Laid-Open No. 103480/1983). However, although the laminates obtained by these methods have sufficient initial adhesive strength, they have the disadvantage that they are inferior in durability and their adhesiveness decreases over time. In addition, the environmental stress cracking resistance is not sufficient, making it difficult to apply it to chemical containers and corrosion-resistant coatings of steel pipes, which has placed significant limitations on its use. An object of the present invention is to provide a laminate using a polyolefin resin composition that eliminates the above-mentioned drawbacks and has excellent adhesiveness and environmental stress cracking resistance. [A] (a) Consisting of ethylene and 0.2 to 20 mol% α-olefin with a density of 0.900 to 0.940 g/cm ³
30 to 98% by weight of a medium to low pressure ethylene copolymer and (b) 70 to 2% by weight of a polyolefin other than the above (a), and the polyolefin of the above (b) is made of an unsaturated carboxylic acid or a derivative thereof. a polyolefin resin composition containing a polyolefin modified with a polyolefin; and [B] a metal selected from the group consisting of a polyolefin and an ethylene-vinyl acetate copolymer.
The present invention provides a laminate formed by laminating seed materials. (a) in the polyolefin resin composition of the present invention
Among the components, the low-pressure ethylene copolymer is not particularly limited as long as it is composed of ethylene and other α-olefins and can be obtained by a medium-pressure method or a low-pressure method. Specifically, it is an ethylene copolymer having short chain branches consisting essentially of α-olefin residues that are copolymerized with ethylene,
It is an ethylene copolymer that 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 conventionally obtained by high-pressure radical polymerization. Also,
These polyethylenes have a density of 0.900 to 0.940g/
cm ³ and a melt index (MI) of 0.1 to 30 g/10 min are preferable, and these are usually produced by ionic polymerization (gas phase polymerization, solution polymerization) or the like.
On the other hand, other α-olefins to be copolymerized with ethylene include those having 3 to 20 carbon atoms, specifically propylene, butene-1, pentene-1, hexene-1,4-methylpentene-1, octene-1, 1,
Examples include nonene-1, and these may be used alone or in combination of two or more. In the medium and low pressure ethylene copolymer as component (a) above, the above α-olefin is 0.2 to 20
It is introduced in a range of mol%. 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 deteriorate significantly. descend. The polyolefin resin composition of the present invention contains, among the above components (a), a low-pressure ethylene copolymer;
It is composed of polyolefin other than the component (component (b)). The polyolefin as component (b) contains a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof, and may further contain, for example, high-density polyethylene, low-density polyethylene, polypropylene, or a copolymer thereof. can. (a) in the polyolefin resin composition of the present invention
The mixing ratio of component and component (b) is 30 to 98% by weight of component (a), 70 to 2% by weight of component (b), preferably 40 to 2% by weight of component (a).
98% by weight, component (b) 60-2% by weight.
If the proportion of component (a) is less than 30% by weight, durable adhesiveness and environmental stress cracking resistance are insufficient. Furthermore, if the blending ratio of component (b) containing modified polyolefin is less than 2% by weight, the desired improvement in physical properties will be insufficient. In the present invention, it is necessary that the component (b) contains a polyolefin modified with an unsaturated carboxylic acid or a derivative thereof. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, citraconic acid, sorbic acid, mesaconic acid, and angelic acid. In addition, its derivatives include acid anhydrides, esters,
There are amides, imides, metal salts, etc., such as maleic anhydride, itaconic anhydride, citraconic anhydride, methyl acrylate, methyl methacrylate,
Examples include ethyl acrylate, butyl acrylate, monoethyl maleate, acrylamide, maleic acid monoamide, maleimide, N-butylmaleimide, sodium acrylate, and sodium methacrylate. The method for modifying polyolefin with these unsaturated carboxylic acids or derivatives thereof is not particularly limited, and various known methods can be used. For example, the process proceeds by adding a radical initiator to polyolefin 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. There is no particular restriction on the type of polyolefin to be modified here;
It may be selected as appropriate depending on the purpose of use. The content of the unsaturated carboxylic acid or its derivative in the modified polyolefin thus obtained is usually in the range of 0.001 to 15% by weight, preferably 0.005 to 10% by weight. This modified polyolefin is
Not all polyolefins need to be modified, and may be a blend of unmodified polyolefins. The polyolefin resin composition of the present invention having the above-mentioned structure has excellent adhesion to other resins and metals, and its adhesive strength does not deteriorate even when exposed to heat, water, salt water, etc., and is resistant to It has excellent environmental stress cracking resistance. Therefore, this resin composition exhibits excellent properties when forming a laminate with other resins or metals, or when making a blend with other resins. In addition to the above-mentioned components, the resin composition of the present invention may optionally contain various additives such as rubbers, ethylene-vinyl acetate copolymers, antioxidants, and ultraviolet absorbers, as well as fillers. It is also effective to add the following as appropriate. The present invention is a laminate formed by laminating the above polyolefin resin composition ([A] layer) and a specific material ([B] layer). Here, the materials constituting the [B] layer include metals such as aluminum, iron, galvanized iron, tinplate, and copper, polyolefin, and ethylene.
Polymer materials such as vinyl acetate copolymers are used. The material constituting these [B] layers may be an unprocessed plate-like body or a processed product such as aluminum foil or polyolefin film. The laminate of the present invention can be laminated into two or more layers to obtain a desired sheet or film by applying known methods such as thermocompression bonding, in-die lamination, and outside-die lamination. A blow molded product can be obtained by blow molding. In addition, when laminating the [A] layer and the [B] layer,
Of course, an adhesive such as epoxy resin may be used. The thus obtained laminate of the present invention has significantly improved interlayer adhesion (peel) strength, and also has improved properties such as gas barrier properties, oil resistance, and water resistance, and also has improved thermoformability. It has the characteristics of not only good hardness but also excellent environmental stress cracking resistance. Therefore, 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, examples of the present invention will be shown. Examples 1 to 4 and Comparative Examples 1 to 4 (1) Production of modified polyethylene High density polyethylene (melt index:
6.5g/10 minutes, density: 0.956g/ ^cm3 ) 100 parts by weight,
10 parts by weight of maleic anhydride and 0.5 parts by weight of dicumyl peroxide were added to 600 parts by weight of xylene, heated and dissolved, and reacted at 125°C for 2 hours with stirring. 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 (2).
The maleic anhydride content of the obtained modified polyethylene was 2.1% by weight, and the melt index (MI) was 0.5 g/10 minutes. (2) Preparation of sheets and laminates of resin compositions The formulations shown in Table 1 were fed to a twin-screw kneading extruder and extruded at 200°C to obtain pellets. Sheets with thicknesses of 0.3 mm and 3 mm were produced from the pellets by compression molding. Next, sandblasted steel plate (thickness 3mm, JIS
G3141, SPCC-SD) After applying thermosetting epoxy adhesive on the surface and curing at 130℃ for 2 minutes, overlap the 0.3mm sheets and heat at 130℃ under pressure.
A resin-metal laminate was obtained by heating and melting and pressing at 10 kg/cm ³ for 3 minutes. Table 1 shows the measurement results of the 90 degree peel strength and mixed salt water peeling of these laminates. Table 1 also shows the results of measuring environmental stress cracking resistance (ESCR) using the sheet with a thickness of 3 mm. Example 5 and Comparative Example 5 According to the procedure of Example 1, xylene-degreased steel plates were heat-melted and pressed for 5 minutes at 150° C. and 10 Kg/cm ³ to obtain laminates. Table 1 shows the measurement results of 90 degree peel strength, heat peel resistance after being left in an oven at 80° C. for 100 hours, and ESCR of these laminates.

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Claims (1)

[Claims] 1 [A] (a) Consisting of ethylene and 0.2 to 20 mol% α-olefin with a density of 0.900 to 0.940 g/cm ³ ,
30 to 98% by weight of a low-pressure ethylene copolymer and (b) 70 to 2% by weight of a polyolefin other than the above (a), and the polyolefin of the above (b) is modified with an unsaturated carboxylic acid or a derivative thereof. A laminate comprising a polyolefin resin composition containing a polyolefin and [B] one material selected from the group consisting of a metal, a polyolefin, and an ethylene-vinyl acetate copolymer.