JPH0519461B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a laminate having a layer of a chlorine-containing thermoplastic resin such as a vinyl chloride polymer or a vinylidene chloride polymer and having strong interlayer adhesion.

(Prior art) Among chlorine-containing thermoplastic resins, polyvinylidene chloride has low moisture permeability and excellent gas barrier properties and oil resistance, so it is used as a gas barrier material like polyamide and saponified ethylene-vinyl acetate copolymer. Its use in food packaging containers is being considered.

Furthermore, polyvinyl chloride is used in many applications in an extremely wide range of fields.

However, the softening point and thermal decomposition point of vinylidene chloride homopolymers are very close to each other, and in the absence of suitable plasticizers and stabilizers, it is usually internally plasticized by copolymerizing with vinyl chloride, acrylonitrile, etc. Workability is improved by lowering the softening point. Therefore, since polyvinylidene chloride used for food packaging has low rigidity and cannot be used as a container by itself, and also to reduce costs, various studies have been conducted on laminating polyvinylidene with polyolefin.

Further, polyvinyl chloride is preferably laminated with polyolefin from the viewpoint of food stability.

As a specific method, for example, an ethylene-vinyl acetate copolymer is used for the adhesive layer.

(Problems to be Solved by the Invention) However, the method of using an ethylene-vinyl acetate copolymer for the adhesive layer has poor adhesive properties, especially heat-resistant adhesive properties, and has a significantly lower softening point than chlorine-containing thermoplastic resins. Because of the low viscosity, the viscosity of the adhesive layer becomes low during lamination by coextrusion, making molding difficult, which is not desirable.

The present invention was made with the aim of improving these drawbacks, and it was discovered that when a specific modified polymer composition is used, the adhesion is significantly improved and the purpose is achieved. .

(Means for Solving the Problems) That is, the present invention provides a method in which “a layer of a chlorine-containing thermoplastic resin and a part or all of a crystalline α-olefin polymer are grafted with 3% by weight or more of an acrylic ester. A chlorine-containing thermoplastic, characterized in that it consists of a layer of a composition consisting of a modified crystalline α-olefin polymer and an acrylic ester polymer, with a total content of acrylic esters of 25 to 75% by weight. "Plastic resin laminate".

Since the laminate of the present invention has strong interlayer adhesion and has the advantages of a chlorine-containing thermoplastic resin and the properties of a polyolefin, it can be highly expected to be applied not only to industrial products but also to the field of daily necessities.

(Function) Examples of the chlorine-containing thermoplastic resin used in the present invention include vinyl chloride, vinylidene chloride homopolymers, and copolymers containing these as main components (e.g., ethylene-vinyl chloride copolymers, propylene-vinylidene chloride copolymers, etc.). (vinyl copolymers, etc.), chlorinated polyolefins, etc., and can be appropriately selected from commercially available products. Among these, polyvinylidene chloride is preferred in terms of adhesiveness.

In addition, other resins that are compatible with the chlorine-containing thermoplastic resin (in the case of mixing in large amounts), resins that are not compatible with it (in the case of mixing in small amounts, for example, 30% by weight or less),
Fillers, colorants, stabilizers, etc. may be appropriately blended and used.

In addition, the modified polymer composition constituting the other layer used in the present invention may be modified by the method described above, in which part or all of the crystalline α-olefin polymer is graft-modified with 3% by weight or more of an acrylic ester. "A composition comprising a modified crystalline α-olefin polymer and an acrylic ester polymer, and the total content of acrylic ester is 25 to 75% by weight." The acrylic ester polymer may be a blend or a homopolymer of acrylic esters produced during graft modification.

Here, the crystalline α-olefin polymer is, for example, ethylene, propylene, butene-1, hexene-1, heptene-1, 4-methylpentene-
1. A homopolymer or mutual copolymer of α-olefins such as octene-1, or a majority weight of these α-olefins and other polymerizable monomers, such as vinyl esters (vinyl acetate, etc.), unsaturated Carboxylic acids or their derivatives (acrylic acid, maleic anhydride, methyl methacrylate, ethyl acrylate, etc.), unsaturated aromatic monomers (styrene, α
-methylstyrene, etc.), unsaturated organic silanes (vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, etc.), etc. Among these, preferred are polymers consisting only of α-olefins, such as low, medium and high density polyethylene, ethylene-propylene copolymers,
They include ethylene-butene copolymers, polypropylene, propylene-butene copolymers, etc., and α-olefin polymers having 3 to 12 carbon atoms are particularly preferred in terms of heat resistance.

These polymers are crystalline, with a crystallinity of 10
% or more, but preferably 20-60%
belongs to.

In addition, the above acrylic acid ester polymer is
For example, it is an alkyl ester homopolymer or copolymer of acrylic acid or methacrylic acid, and specific examples of this alkyl include methyl, ethyl,
Examples include propyl, butyl, 2-ethylhexyl, etc., and alkyl having 1 to 4 carbon atoms are particularly preferred from the viewpoint of adhesiveness.

Here, the copolymer is one containing an acrylic acid ester as a component in the majority by weight, as described above for the α-olefin polymer.

Further, as the monomer of the acrylic acid ester (monomer used for graft modification), those listed as constituent monomers in the above acrylic ester polymer can be used. This acrylic acid ester monomer can also be graft copolymerized in the presence of other copolymerizable vinyl monomers, if necessary.

Next, the method of graft modification is solution grafting,
It does not matter whether it is melt grafting, aqueous suspension grafting, or radiation grafting, but from the viewpoint of uniform dispersion of acrylic acid ester monomers and suppression of gel formation, aqueous suspension grafting (for example, see JP-A-59-68318)
is preferred.

If the amount of acrylic acid ester monomer grafted onto the crystalline α-olefin polymer is less than 3% by weight, it is difficult to achieve the initial objective in terms of the balance between adhesiveness and strength. Furthermore, if the content of all acrylic acid ester monomers is less than 25% by weight, adhesiveness will be insufficient, and if it exceeds 75% by weight, moldability will deteriorate.

This resin layer may also contain petroleum resins, tackifiers, etc. that are commonly used in hot melt adhesives.

As a method for manufacturing the laminate of the present invention, a method of laminating the resins of both layers by coextrusion molding, press molding, extrusion lamination, etc. is used.

Note that the laminate of the present invention includes not only these two layers, but also a laminate consisting of three or more layers including these two layers. At this time, materials that can be used as base materials for other layers include, for example, fluorocarbon resins such as polyvinylidene fluoride; styrene resins such as acrylonitrile-butadiene-styrene resins and polystyrene; polyolefin resins such as polyethylene and polypropylene; acrylonitrile - Various rubbers such as butadiene rubber, styrene-butadiene rubber; Metals such as aluminum and iron; Thermosetting resins such as unsaturated polyester, epoxy resin, and urethane resin; Thermoplastic polyester, polycarbonate,
Possible materials include engineering resins such as nylon.

The modified polymer composition constituting one layer of the laminate of the present invention can be bonded to these substrates without using an adhesive or with an adhesive as necessary.

At this time, in laminating with other base materials, it is necessary to ensure that the modified polymer composition used in the present invention contains unsaturated organic carboxylic acids or derivatives thereof, unsaturated organic carboxylic acids, unsaturated organic carboxylic acids, derivatives thereof, Those containing a glycidyl compound in the form of graft modification or copolymerization are preferred from the viewpoint of adhesive properties.

Here, "contained in the form of graft modification or copolymerization"
This refers to a method in which these unsaturated compounds are simultaneously grafted together with the acrylic ester monomer during graft copolymerization of the acrylic ester monomer, or as an α-olefin polymer or an acrylic ester polymer. A method of using a product containing these unsaturated compounds in the form of graft or copolymerization in advance, or graft copolymerization of these unsaturated compounds to a modified polymer composition containing a predetermined amount of an acrylic acid ester monomer. How to make a modified polymer composition α
- There is a method of kneading an α-olefin polymer similar to an olefin polymer or an acrylic acid ester polymer containing these unsaturated compounds in the form of graft modification or copolymerization.

In addition, unsaturated carboxylic acid or its derivative is
Unsaturated compounds having carboxylic acid groups, acid anhydride groups, ester groups, carboxylic acid metal salts, carboxylic acid amide groups, etc. Examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, etc. and their derivatives. Maleic anhydride is particularly preferred.

Examples of unsaturated glycidyl compounds include glycidyl methacrylate, glycidyl acrylate, and the like.

Since the laminate of the present invention can also be obtained during molding of a chlorine-containing thermoplastic resin, it is particularly useful for coating the inner surface of pipes such as metal pipes, which have conventionally been difficult to laminate.

(Example) Next, an example will be shown, and each evaluation in the example was based on the following method.

(1) Adhesion: After cutting the laminate into 1cm wide strips and peeling off a portion, the fluororesin and base material were placed between the chucks of an Instron type testing machine and measured at a speed of 50mm/min. .

(2) Acrylic acid ester content: Determined by infrared analysis after vacuum drying the obtained modified polymer at 60°C for 10 hours.

Reference example 20 kg of pure water, 0.6 kg of tribasic calcium phosphate as a suspending agent, and 0.6 g of sodium dodecylbenzenesulfonate are mixed into a 50-capacity autoclave to form an aqueous medium, and propylene-ethylene copolymer with a particle size of 3 to 4 mm is mixed into this. 5 kg of combined material (MFR 6 g/10 minutes, ethylene content 4% by weight) was added and stirred to suspend. Separately 15g t-butyl peroxybenzoate
was dissolved in 5 kg of n-butyl acrylate, and this was added to the above suspension system, and the system was purged with nitrogen. Furthermore, the temperature inside the autoclave was raised to 90 DEG C., and the mixture was left at this temperature for 4 hours with stirring to impregnate n-butyl acrylate containing a polymerization initiator into the propylene-ethylene copolymer particles.

Next, the temperature of this suspension was raised to 105°C, and polymerization was carried out by standing at this temperature for 2.5 hours while stirring, and the temperature was further raised to 125°C and maintained for 8.5 hours to complete polymerization.

After cooling, the solid contents were taken out and washed with water to obtain 10 kg of n-butyl acrylate modified propylene-ethylene copolymer particles. Obtained modified propylene
The n-butyl acrylate content in the ethene copolymer was 50% by weight.

Example The n-butyl acrylate-modified propylene-ethylene copolymer obtained in Reference Example and vinylidene chloride resin (commercially available reagent) were each molded into a 0.5 mm thick sheet at 200° C. by compression molding.

The obtained sheets were further laminated by compression molding at 200°C to obtain a laminated sheet of the modified propylene-ethylene copolymer and vinylidene chloride resin.

The adhesive strength between each layer of the obtained laminate was 3Kg/cm
It was hot.

Comparative Example 1 Comparative example 1 was carried out in the same manner as in the example except that the propylene-ethylene copolymer used in the reference example was used instead of the modified propylene-ethylene copolymer, and no adhesion occurred at all.

Comparative Example 2 In the reference example, the raw materials propylene-ethylene copolymer and n-butyl acrylate were 8 kg and 2 kg, respectively.
10 kg of n-butyl acrylate modified propylene-ethylene copolymer was obtained in the same manner except that 6 g of -butyl peroxybenzoate was used. The n-butyl acrylate content in the resulting modified propylene-ethylene copolymer was 20% by weight.

Next, according to the example, the above acrylic acid n
A laminate sheet of the -butyl-modified propylene-ethylene copolymer and the vinylidene chloride resin was molded.
An attempt was made to measure the adhesive strength between each layer of such a laminate, but the adhesive strength was too weak to be measured.

Comparative Example 3 Low-density polyethylene melt-kneaded in an extruder (melt index 2 g/10 minutes, density 0.920 g/cm ³ )
A modified polyethylene was obtained by graft-modifying the polyethylene with maleic anhydride. This modified polyethylene and vinylidene chloride resin (commercially available reagent) were compressed and molded for 200 min.
Sheets each having a thickness of 0.5 mm were formed at ℃. The obtained sheets were further laminated by compression molding at 200°C to produce a laminate. An attempt was made to measure the adhesive strength between each layer, but the adhesive strength was too weak to be measured.

Claims (1)

[Claims] 1 Layer of chlorine-containing thermoplastic resin and crystallinity α
- Part or all of the olefin polymer is 3% by weight
Consists of a layer of a composition comprising a modified crystalline α-olefin polymer graft-modified with the above acrylic ester and an acrylic ester polymer, and the total content of acrylic ester is 25 to 75% by weight. A chlorine-containing thermoplastic resin laminate characterized by: