JPS6364725A - Manufacture of laminated material - Google Patents

Abstract

PURPOSE:To obtain easily a laminated material having an interlaminar adhesive strength being sufficiently enough for the practical application, by carrying out a corona discharge treatment on the surface of a membrane formed of a resin composition consisted of a polypropylene resin and an inorganic powder and laminating and fusing another material on this treated surface. CONSTITUTION:Either a propylene-ethylene random copolymer or a blend of polypropylene and an ethylene polymer is used as a polypropylene resin. 0.5-70wt% inorganic powder, e.g., titanium oxide and so on are usually blended with the resin. Reinforcing materials, rubbers, lubricants, anti-static agents, plasticizers and coloring agents are properly added with them. At first, a membrane like material, such as a film, a sheet and the like is formed from the resin composition. A corona discharge treatment is carried out on the surface of this membrane like material while the surface temp. is being kept at 80-250 deg.C under an atmosphere wherein the air content is 50vol% or less. A gas barrier sheet or film consisted of another material such as saponified ethylene-vinyl acetate copolymer and so on is laminated and fused on this treated surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a laminated material, and more specifically, to inexpensively and safely manufacture a laminated material with excellent adhesive strength without the need for adhesives. The laminated material produced according to the present invention can be used as a packaging material for various foods, beverages, pharmaceuticals, industrial machinery parts, etc.

[Saponified vinyl monoacetate copolymer, polyvinylidene chloride, nylon,
Laminated materials made of gas/barrier materials such as aluminum foil have the excellent properties of polypropylene resin, such as heat resistance, strength, rigidity, and moisture permeability, as well as properties such as gas barrier properties, and are useful for various foods, It is widely used as packaging bags or containers for beverages, pharmaceuticals, industrial machinery parts, etc. However, polypropylene resin and these materials with gas barrier properties essentially do not have adhesive properties, so it is not possible to produce a laminated material by ordinary coextrusion molding or lamination. Methods that have been adopted include coextrusion molding of a polyolefin graft-modified with saturated carboxylic acid or its derivatives as an adhesive resin, or wet-processing the surfaces of the respective materials and then laminating them. However, both methods require adhesives in addition to the respective materials, and also require equipment and manufacturing processes for using the adhesives, resulting in high production costs and low productivity.

As a result of intensive study on a method for manufacturing a laminated material that has excellent interlayer adhesion and can be used as various packaging materials without using adhesives, the present inventors selected a specific raw material polypropylene resin and specific corona treatment conditions. It was discovered that a laminated material having interlayer adhesion strength sufficient for practical use can be easily obtained by this method, and the present invention was completed based on this knowledge.

[Means to Solve the Problems] That is, the present invention provides a polypropylene resin consisting of a propylene-ethylene random copolymer or a blend of polypropylene and an ethylene polymer, in which no inorganic powder is added. The surface of a film-like body formed from a resin composition containing .5 to 70% by weight is heated to 80°C
The present invention provides a method for manufacturing a laminated material, which comprises performing a corona discharge treatment at 250° C. in an atmosphere with an air content of 50% by volume or less, and then laminating and fusing other materials on the treated surface.

In the present invention, a resin composition basically consisting of a polypropylene resin and an inorganic powder is used as a raw material.

Here, the polypropylene resin needs to contain ethylene as a copolymer or mixed component, rather than a propylene homopolymer. Specifically, it is either a propylene-ethylene random copolymer or a blend of polypropylene and an ethylene polymer. Note that the random copolymer includes a mixture of a random copolymer obtained by a multistage polymerization method and a propylene homopolymer, and the propylene-ethylene random copolymer has an ethylene content of 2 to 30% by weight. , preferably 2 to 20% by weight. The melt index □II) of this propylene-ethylene random copolymer is not particularly limited, and is usually 0.1 to 20 g/10 min. In addition, a blend of polypropylene and ethylene polymer is homopolypropylene and polyethylene (low density, medium density).

high density), ethylene-α-olefin copolymer.

Whether it is a blend of ethylene-based polymers such as ethylene-propylene rubber (EPR), terpolymer (EPDM) made by copolymerizing ethylene-propylene with a small amount of diene, or ethylene-unsaturated acid copolymer. Good.

In this case, a propylene-ethylene random copolymer may of course be included, but the molecular weight, XI, etc. of the polypropylene are not particularly limited.

Usually, Ml is 0.1 to 20 g/10 min, preferably 0.
5 to 10 g/10 minutes.

Further, the content of the ethylene component in the ethylene polymer is not particularly limited as long as it is 2% by weight or more, and
There are no particular restrictions on the mixing ratio of the ethylene polymer and polypropylene, and it may be determined as appropriate depending on the type of material for the lining layer, the intended physical properties, etc. Generally, the mixing ratio of the ethylene polymer is 40% by weight. Below, preferably 1 to
It is 30% by weight. In any case, in the present invention, the purpose of the present invention cannot be achieved at all if homopolypropylene is used alone as the polypropylene resin. Therefore, it is not possible to contain an ethylene component in the polypropylene resin. The ethylene component is obtained by mixing a propylene-ethylene random copolymer or an ethylene polymer.

Next, there are various inorganic powders used in the present invention, such as titanium oxide, talc, clay, silica, kaolin, calcium carbonate, etc. calcium acid, fE
barium acid, magnesium oxide, magnesium hydroxide,
Calcium silicate.

Examples include magnesium silicate, zeolite, silicic anhydride, and carbon black. There is no particular restriction on the particle size, etc., but it is usually 0.1 to 30, preferably 0.2 to 20.
A material with a weight of approximately 100 g is used.

This inorganic powder is usually added to the resin composition with a concentration of 0.5 to 70%.
It is blended in a proportion of 1 to 50% by weight, preferably 1 to 50% by weight. Here, the blending ratio of the inorganic powder is appropriately selected depending on the type of the inorganic powder, the strength, rigidity, heat resistance, use, etc. of the laminated material. In particular, the present invention is characterized in that excellent effects can be obtained by adding several weight percent.

The resin composition used in the present invention consists of the above-mentioned polypropylene resin and inorganic powder, and optionally contains stabilizers against oxidation, heat, light, etc., and glass fiber.

Reinforcing materials such as carbon fibers, rubbers, lubricants, antistatic agents, plasticizers, colorants, etc. can be added as appropriate.

In the present invention, a membranous body such as a film or a sheet is first formed from such a resin composition. Here, the film-like body can be formed by a conventional method, and after thoroughly kneading the above raw materials,
It can be obtained by extrusion molding. in this case,
It may be multilayer coextrusion molded with other resins, or may be lined with aluminum foil or other heat-resistant resin sheets, if necessary.

Next, such a film-like body is subjected to a corona discharge treatment, and at this time, it is necessary to keep the surface of the film-like body at a temperature of 80 to 250°C, preferably 100 to 200°C.

Therefore, if the surface of the film-like body is kept at the above temperature after extrusion molding, for example, the sheet extruded from the goo outlet of the extrusion molding machine can be directly extruded into the gas atmosphere chamber of corona discharge. In some cases, corona discharge can be performed continuously. In addition, if the surface of the film-like material is lower than the above temperature, it may be reheated and then subjected to corona discharge treatment at the above temperature.Here, reheating may be performed using heating rolls, radiant heating, hot air heating, etc. In addition, in the case of a lined film, only the surface to be treated needs to be heated; in any case, the treatment temperature of the present invention may be as long as the temperature of the treated surface is within the above temperature range. , processing equipment,
An optimal method may be selected depending on the process. In this case, the corona treatment atmosphere temperature may be set to 80° C. or higher.

Corona discharge treatment is performed on the surface of the film-like body that is maintained within such a temperature range. This treatment has an air content of 50
The process can be carried out in an atmosphere of 50% by volume or less.A method for carrying out in such an atmosphere is to introduce an inert gas such as carbon dioxide gas, dinitrogen oxide gas, water vapor, argon, helium, etc. Examples include a method of carrying out corona discharge treatment in a treatment tank with replacement by % by volume, or a method of carrying out corona discharge treatment while blowing the above-mentioned gas onto the surface to be treated with corona discharge. Particularly preferred as the processing gas here are carbon dioxide gas and dinitrogen oxide gas.

In corona discharge treatment, a high voltage is applied between a grounded galvanic-coated roll or dielectric-coated metal plate and a knife-shaped electrode placed several inches apart between the two to discharge corona. This is done by running sheets in between.

Although the processing conditions may be arbitrarily determined depending on the processing effect, purpose, etc., the processing is usually carried out at a discharge voltage of 1000 to 5000 volts and an oscillation frequency of 3 to 150 KHz.

In the present invention, the desired laminated material can be manufactured by laminating and fusing other materials on the treated surface that has been subjected to the corona discharge treatment in this manner.

There are no particular restrictions on other materials, but ethylene-
Single-layer or multi-layer sheets or films made of gas barrier materials such as saponified vinyl acetate copolymers, polyvinylidene chloride, nylon, polyester, and polyacrylonitrile are preferred.

In addition, metals such as aluminum foil or laminates thereof can also be used. Such other materials do not need to be corona discharge treated, but may be corona discharge treated. There are no particular restrictions on the conditions for the corona discharge treatment, but the same conditions as described above may be used.

This other material and the corona discharge treated surface of the film-like body subjected to the corona discharge treatment are laminated and fused. For this lamination and fusing, it is necessary that the temperature is such that the surface of at least one of the membrane bodies melts, and preferably the temperature is such that the surface of at least one of the membrane bodies melts.
It is preferable to heat it to a temperature higher than ℃. In the manner described above, a laminated material consisting of two or more layers can be manufactured.

The method for producing the laminated material of the present invention includes, for example, extrusion molding a polypropylene resin compound into a film, and corona treatment in an atmosphere using an inert gas at a high surface temperature of 80 to 250°C. There is a method of laminating another material in the form of a film on this treated surface and fusing it with a pressure roll. By this method, a laminated material can be obtained with high productivity and at low cost.

[Effects of the Invention] According to the present invention, it is possible to produce a laminated material that has high interlayer adhesive strength and has an interlayer adhesive strength equivalent to or higher than that obtained when a modified polyolefin is used as an adhesive resin.

Further, according to the present invention, since no adhesive is required, the cost of raw materials is significantly reduced, and extrusion equipment for this purpose is not required, resulting in low operating costs.

Furthermore, the laminated material can be manufactured inexpensively and safely.

Furthermore, according to the present invention, since rotation is the process of reducing the adhesive strength of the ears by controlling the width of the treated surface, it has practical benefits such as being able to separate and collect unnecessary ears as a product. have

[Example] Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto unless it exceeds the scope of the present invention.

Examples 1 to 9 and Comparative Examples 1 to 4 A 300-thick luripolypropylene-based 81 resin sheet (hereinafter referred to as PP sheet) formed by molding a resin composition formed by blending predetermined amounts of each component shown in Table 1. 1 was set on the heating roll 3 of the corona discharge treatment apparatus shown in FIG. The A-layer sheet 6 was obtained by carrying out a corona discharge treatment (7000 V, 5 KHz) under the conditions shown below, laminating the layers, and then winding them around a take-up roll 7. Note that the roll 3.4 was crimped using a spring.

Table 1 shows the measurement results of the living room peel strength of the obtained laminated sheet.
I used one lined with aluminum foil.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of an apparatus used in experiments for carrying out the method of the present invention. 1...Polypropylene resin sheet. 2...Other materials. 3.4... Heating roll. 5A, 5B...electrodes. 6... Laminated sheet. 7... Winding roll. 8... Weight

Claims (1)

[Claims] 1. As a polypropylene resin, 0.5 to 70% by weight of inorganic powder is blended into a polypropylene resin made of a propylene-ethylene random copolymer or a blend of polypropylene and an ethylene polymer. The surface of the film-like body formed from the resin composition is set at 80°C to 250°C,
1. A method for producing a laminated material, which comprises performing a corona discharge treatment in an atmosphere with an air content of 50% by volume or less, and then laminating and fusing another material on the treated surface. 2. The manufacturing method according to claim 1, wherein the other material is a gas barrier material.