JPH0421587B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a laminate of ethylene vinyl alcohol copolymer resin or polyamide resin and ethylene polymer resin, and more specifically, in producing the laminate, This is related to improvements. A laminate of polar resin such as ethylene vinyl alcohol copolymer resin or polyamide resin and polyolefin resin has characteristics such as oil resistance, oxygen permeability resistance, and fragrance retention, as well as water resistance, heat sealability, impact resistance, etc. It is a composite material that has the following characteristics and is widely used as various packaging materials such as containers and films. It is also common practice to use a polyolefin resin modified with an unsaturated carboxylic acid or the like in order to bond a polar resin and a polyolefin resin that do not adhere by normal gluing. In this technical field, the present inventors have conducted various studies on modified polyethylene resin compositions that can bond well between ethylene vinyl alcohol copolymer resins, polyamide resins, and polymers mainly composed of ethylene. It was discovered that an adhesive layer with good moldability and excellent adhesive performance can be obtained by using a composition consisting of a high-pressure processed low-density polyethylene resin and a medium-low-pressure processed high-density polyethylene resin, which have the following characteristics.The present invention This is the completed version. That is, the gist of the present invention is that when manufacturing a laminate including a polar resin layer selected from ethylene vinyl alcohol copolymer resin and polyamide resin and an ethylene polymer resin layer, ( A) The product (EC) of melt index (MI) and melt tension (MT) values is 20 or more,
and melt index (MI) is 0.1＜MI＜
A composition consisting of 60-90% by weight of high-pressure processed low-density polyethylene with a density of 0.50 (B) 10-40% by weight of medium-low-pressure processed high-density polyethylene with a density of 0.945 or more, which contains both components (A) and (B). A method for producing a laminate, characterized in that a modified polyethylene composition is used in which one or both of the unsaturated carboxylic acids or derivatives thereof are grafted in an amount of 0.03 to 1% by weight based on the total composition. A modified polyethylene resin composition using a mixture of polyethylenes with different properties was published in
33895, JP-A-50-5144, JP-A-52-33941, etc. In particular, in JP-A No. 52-33941, high-pressure polyethylene and medium-low pressure polyethylene are mixed and modified, or they are individually modified with unsaturated carboxylic acids, etc., and then mixed to prevent corrosion of metals. Suitable modified polyethylene is described, and Japanese Patent Publication No. 50-33895 describes metal coating compositions made of high-pressure polyethylene and medium-low pressure polyethylene graft-modified with polar monomers, but in both cases, the main focus is The key is adhesion to metal. Unlike these inventions, the present invention uses a special modified polyethylene resin as an adhesive resin used when manufacturing a laminate of an ethylene polymer and a polar resin selected from ethylene vinyl alcohol copolymer resin or polyamide resin. It is characterized by the use of The special modified polyethylene used in the present invention is not simply a high-pressure polyethylene resin, but is a combination of a high-pressure low-density polyethylene resin that exhibits specific performance and a medium-low pressure polyethylene resin. Adhesive performance to alcohol copolymer resins or polyamide resins is greatly improved. The high-pressure low-density polyethylene resin (A) used in the present invention has a product (EC) of the tension shown by the molten polymer {melt tension (MT)} and the flow index value (MI) of the molten polymer. is a high-pressure low-density polyethylene with a melt index (MI) of 20 or more and a melt index (MI) of 0.1<MI<50. Such high-pressure low-density polyethylene (A) can be produced by either the tubular method or the autoclave method, but when produced by the autoclave method, it can be easily produced by shifting the reaction conditions to high temperature and high pressure. I can do it. Density is 0.910~0.930g/ ^cm2
degree is preferred. In recent years, there has been a polyethylene called linear low-density polyethylene, which has a short branched structure and has a lower density by copolymerizing ethylene and other α-olefins, but this linear low-density polyethylene has poor adhesive strength. It is undesirable. When the EC is less than 20, the desired adhesive strength cannot be obtained, and the upper limit is preferably 40 or less, and more preferably 35 or less. If it exceeds 40, molding becomes difficult and there is little economic merit. Melt index (MI) is ASTM-D-
Value measured according to 1238-57T (190℃) (g/10
min), and in the present invention, it is greater than 0.1 g/10 min.
High-pressure low density polyethylene with a rate of less than 50 g/10 minutes is used, preferably greater than 0.5 g/10 minutes and less than 5 g/10 minutes. The melt tension was measured using a melt tension meter manufactured by Toyo Seiki Co., Ltd. with a diameter of 2 mmφ, a length of 8 mm, and an inflow angle.
Installed 180° orifice, temperature 160°C, extrusion amount
This is the value (g) measured at a take-up speed of 152 cm/min at 0.25 g/min. The medium-low pressure high-density polyethylene (B) may be any polyethylene obtained by polymerization such as the usual Ziegler method or Phillips method, and has a density of 0.945 containing an ethylene homopolymer or a small amount of copolymer component.
It is high-density polyethylene of g/cm ² or more. density
If less than 0.945 g/cm ² of polyethylene is used, the effect of the present invention will be small. The blending ratio of components (A) and (B) is 60 to 90% by weight of component (A) and 10 to 40% by weight of component (B). (B) The content of component
If it is less than 10% or more than 40%, the adhesive performance will be low, which is not desirable. More desirably, the amount of component (B) is 15 to 35% by weight. Examples of unsaturated carboxylic acids or derivatives thereof include unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, maleic acid, and endo-bicyclo[2.2.1]-5.
- unsaturated polycarboxylic acids such as heptene 2,3 dicarboxylic acids, and their acid anhydrides, esters, imides, etc. Among these, unsaturated dicarboxylic acid anhydrides, particularly maleic anhydride, are preferred. In order to create modified polyethylene, a method using a commonly known graft reaction can be used.
That is, the unsaturated carboxylic acid or its derivative monomer, the radical generator, and/or components (A) and (B) may be brought into contact with each other under conditions in which the radical generator is effective, and the reaction conditions are as follows: Any of the following methods may be used: a melt-kneading method using an extruder or the like, a method in which the polymer is dissolved in a solvent, and a slurry method in which solution-processed polymer particles are suspended. The component modified by a graft reaction of an unsaturated carboxylic acid or a derivative thereof is at least one of the components (A) and (B), and both components may be modified by a graft reaction. Preferably (B)
It is preferable that the component is modified by a graft reaction, or both components (A) and (B) are modified by a graft reaction. The amount of unsaturated carboxylic acid or derivative thereof to be grafted may be from 0.03 to 1% by weight, based on the total composition. If it is less than 0.03%, the adhesiveness will be poor, and if it exceeds 1%, problems such as coloring and gelation may occur, and the adhesive performance will not be improved, so it is not necessary. Additives such as stabilizers, pigments, and fillers commonly used in polyolefin resins can also be added to the adhesive composition used in the present invention to the extent that their effects are not impaired. It is also possible to add modifying materials such as ethylene/α-olefin copolymer rubber. Further, depending on the case, other polyolefins of the same or different type can be added to the composition to form a composition. The adhesive composition obtained as a result of such blending desirably has a melting characteristic of about 0.1 to 30 g/10 min, preferably about 0.5 to 10 g/10 min, and for this purpose, components (A) and (B) are It is necessary to select the appropriate one. In the present invention, the adhesive composition is used as an intermediate layer between an ethylene vinyl alcohol copolymer resin or a polyamide resin and an ethylene polymer resin to make a laminate by melt laminating by multilayer coextrusion molding or the like. . The ethylene polymer resin referred to here refers to homopolymers and copolymers mainly composed of ethylene monomer, and the comonomer component is α-olefin having about 3 to 12 carbon atoms,
Any comonomer copolymerizable with vinyl acetate, dienes such as non-conjugated dienes and butadiene, acrylic acid, methacrylic acid and derivatives thereof, and ethylene may be used. Furthermore, the mode of copolymerization is not limited to random copolymers, but also includes copolymerization in graft or block forms. The ethylene-vinyl alcohol copolymer is an ethylene-vinyl acetate copolymer whose acetic acid groups are partially or almost saponified to form OH groups, and its chemical composition is not limited; 100,000, ethylene content 10 mol% ~
Ethylene content of 70 mol% is used, but considering gas barrier properties, film formability, etc., the ethylene content is 50%.
~30 mol% ethylene-vinyl acetate copolymer,
Preferably, those obtained by saponification have a saponification degree of 90% or more. Polyamide resin is a linear polymer with an acid amide bond obtained by ring opening of lactam, condensation of diamine and dicarboxylic acid, etc., and has an average molecular weight.
15,000 to 60,000, [η] = about 1.0 to 6.0, and specifically, nylon 6, nylon 6.6, nylon 6.10, nylon 11, nylon 6.11, nylon 6T, etc. can be used. An example of the method of the present invention will be described below using an example, but the present invention is not limited to the following example unless the gist thereof is exceeded. Production example and adhesive strength measurement method [Example of high-pressure method low-density polyethylene production] [Polyethylene (A)] Using an autoclave-type high-pressure reactor, ethylene was polymerized using a radical initiator to obtain the following two types of polyethylene. .

[Table] [Example of production of high-density polyethylene by medium and low pressure method] [Polyethylene (B)] Using triethylaluminum and a solid catalyst component obtained by reducing a mixture of titanium tetrachloride and vanadium oxytributoxide with ethylaluminum sesquichloride, normal hexane was produced. Polymerization was carried out by mixing a small amount of propylene and putene-1 as comonomers with ethylene.

[Example of manufacturing modified polyethylene A predetermined amount of maleic anhydride and α,α′-ditertiarybutylperoxyparaisopropylbenzene are mixed with polyethylene (A) and/or polyethylene (B), and the mixture is uniaxially extruded with an inner diameter of 30 mmφ and L/D=24. The copolymer was modified by melt-kneading and grafting using a machine at 210°C. The grafting rate was determined by infrared spectroscopy after removing unreacted monomers by extraction with acetone. [Adhesive strength measurement method]

The inner layer was formed by coextruding a modified polyethylene composition and an ethylene-vinyl alcohol copolymer resin (ethylene content: 39 mol%, saponification degree: approximately 100%, melt index at 210°C: 8 g/10 minutes) in a die. Adhesive polyethylene composition, outer layer is ethylene-
A composite inflation film made of vinyl alcohol resin was created. Die inner diameter 75mmφ, die temperature 205℃ Polyolefin composition side extruder L/D
= 26, temperature 205°C, ethylene vinyl alcohol resin side extruder L/D = 26, temperature 205°C.
Winding speed 6.2m/min, blow-up ratio 2,
The thickness of the ethylene vinyl alcohol resin is 25μ, and the thickness of the modified polyethylene is 25μ. The T peel strength of this composite film was measured in accordance with JISK6854. Examples 1 to 4 Using high-pressure polyethylene a-1, a composition was prepared by blending a predetermined amount of polyethylene b-1, b-2, and b-3 grafted with maleic anhydride according to the above production example, and ethylene vinyl alcohol The adhesive strength with the copolymer resin was measured. The results are shown in Table-1. Example 5 A composition was prepared in which maleic anhydride was grafted all over using high-pressure polyethylene a-1 and medium-low pressure polyethylene b-2, and the adhesive strength was measured. The results are shown in Table-1. Comparative Example 1 As a comparison between Examples 2 and 3, a composition containing 50% component (B) was prepared. It is clear that the effect decreases as the amount of blend increases. The results are shown in Table-1. Comparative Example 2 Comparison with Example 2 was made using high pressure polyethylene a-2 having a small melt tension. Adhesive strength is lower than a-1 which has high melt tension. The results are shown in Table-1. Comparative Example 3 Linear low density polyethylene was used as component (B). The adhesive strength is not as good as that of Examples 1, 2, and 4.
The results are shown in Table-1. Comparative Example 4 A comparison with Example 5 was made using a-2 polymer with low melt tension. A-2, which has a low melt tension, has low adhesive strength. The results are shown in Table-1.

【table】

Claims (1)

[Scope of Claims] 1. When producing a laminate containing a polar resin layer selected from ethylene vinyl alcohol copolymer resin and polyamide resin and ethylene polymer resin, as an adhesive resin layer for both layers (A ) The product (EC) of the melt index (MI) value and the melt tension (MT) value is 20 or more, and the melt index (MI) is 0.1 <
High pressure low density polyethylene with MI<50 60~
90% by weight (B) A composition consisting of 10 to 40% by weight of medium-low-pressure high-density polyethylene with a density of 0.945 or more, containing an unsaturated carboxylic acid in either or both of the components (A) and (B). A method for producing a laminate, characterized in that a modified polyethylene composition is used in which 0.03 to 1% by weight of a derivative thereof is grafted based on the total composition. 2 Claim 1 characterized in that maleic anhydride is used as the unsaturated carboxylic acid derivative
The manufacturing method described in section. 3. The manufacturing method according to claim 1, wherein at least component (B) is modified by a graft reaction.