JPH0548743B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an easily peelable multilayer material, and more particularly to a multilayer material that is hygienic and easy to manufacture and whose peel strength can be arbitrarily set depending on the application. . [Prior Art and Problems to be Solved by the Invention] Polypropylene resins have excellent heat resistance, rigidity, moisture permeability, etc., and are therefore used in various packaging fields. Particularly when used for packaging foods, drinks, etc., it has been used as a multilayer material with a gas barrier resin layer from the viewpoint of long-term storage stability. These multilayer materials are usually T-die or inflation molded into a film or sheet shape, and then subjected to secondary processing such as stretching or rolling, and are made into bags or sheets that are thermoformed depending on the purpose of use. It is used as a packaging material for various products. However, the packaging materials obtained through the above-mentioned processes are susceptible to dust adhesion and contamination by germs during the manufacturing, storage, transportation, secondary molding, etc. of the packaging materials.
In many cases, it cannot be used for packaging precision electronic mechanical parts, foods, etc. A possible solution to this problem is to wash and sterilize the packaging material before packaging, but this requires additional steps and increases packaging costs. Another possible method is to laminate an easily peelable film, but this method requires a laminating step, which complicates the manufacturing process, and it also has the disadvantage of causing contamination during the laminating step. Furthermore, with this method, it is difficult to set an arbitrary peel strength. [Means for Solving the Problems] The purpose of the present invention is to eliminate the above-mentioned conventional drawbacks, and to provide a multilayer material whose peel strength can be arbitrarily set and which is free from contamination from dust and germs when peeled off during use. It is something to do. That is, the present invention provides (A) polypropylene resin
100 parts by weight and 0.5 parts of low crystalline α-olefin copolymer
An easily peelable multilayer material (hereinafter referred to as the first invention) consisting of at least two layers: a polypropylene resin composition layer containing ~3 parts by weight and (B) a resin layer that is non-fusible with the polypropylene resin. ), and an easily peelable multilayer material formed by forming (C) a gas barrier resin layer on the (A) polypropylene resin composition layer side of the multilayer material via an adhesive resin layer. (hereinafter referred to as the second invention). The multilayer material of the first invention has at least
It consists of two layers (A) and (B), and the polypropylene resin composition layer (A) contains 0.5 to 3 parts by weight of low crystalline α based on 100 parts by weight of the polypropylene resin. - It is obtained by blending an olefin copolymer. Various types of polypropylene resins can be used as the polypropylene resin constituting layer (A), but usually propylene homopolymers, random copolymers of propylene and 30% by weight or less of ethylene, butene-1, etc. There are mixtures of these. Here, as a random copolymer,
It may be produced by two-stage or more multi-stage polymerization as disclosed in No. 226549. In addition, the melt index of this polypropylene resin is generally 0.1 to 15g/10 minutes,
Preferably 0.2-10g/10 minutes, more preferably 0.3
~5g/10 minutes. In this case,
In the case of sheet materials for container molding, if the melt index exceeds 15 g/10 minutes, the melt strength of the sheet will be low, while if it is less than 0.1 g/10 minutes, the fluidity will be poor, and both will be difficult to heat. Secondary formability such as molding becomes difficult. Note that these polypropylene resins may contain fillers such as talc and calcium carbonate in an amount of 300 parts by weight or less per 100 parts by weight of the polypropylene resin. Moreover, various other additives can also be added. The low-crystalline α-olefin copolymer blended into the above polypropylene resin is an elastic copolymer mainly composed of α-olefin, and usually has a crystallinity of 40% or less and a density of 0.85 to 0.90. g/ ^cm3 ,
Melt index (MI) (230℃) 0.1~100g/
10 minutes, preferably crystallinity 30% or less, density 0.85~
0.88g/cm ³ , MI (230°C) 0.5-50g/10 minutes. Here, the α-olefin component units include ethylene, propylene, butene-1, pentene-1,
Examples include 4-methylpentene-1, hexene-1, octene-1, decene-1, and dodecene-1. A low-crystalline α-olefin copolymer usually consists of two or more α-olefin components, and in addition to these α-olefin component units, a small amount of other copolymerizable components, such as 1,4-
It may also contain non-conjugated diene components such as hexadiene, dicyclopentadiene, and 5-ethylidene-2-norbornene, and conjugated diene components such as butadiene and isoprene. Specifically, elastic copolymers containing ethylene or propylene as a main component are preferred, such as ethylene-propylene copolymer (EPR), ethylene-propylene-diene copolymer (EPDM), and ethylene-butene-1 copolymer. Union,
Examples include propylene-ethylene copolymers. The content of the α-olefin component is usually 85 mol%, preferably 90 mol% or more. In the polypropylene resin composition layer of layer (A), the amount of the low crystalline α-olefin copolymer blended is 0.5 to 3 parts by weight, preferably 0.7 to 2 parts by weight, based on 100 parts by weight of the polypropylene resin. It is a proportion of parts by weight. The amount of low crystallinity α-olefin copolymer is
If it is less than 0.5 part by weight, it is not preferable because it will peel off during various handling or transportation during multilayer body molding. Moreover, if it exceeds 3 parts by weight, it is not suitable because it is difficult to peel off during use. On the other hand, the resin layer (B) has a non-fusion property with the polypropylene resin used for the layer (A) mentioned above, that is, it has the ability to be easily peeled off even if laminated with the polypropylene resin layer. . Here, in order to have appropriate peelability, the interlayer peel strength is usually 100 g/25 mm or less, preferably 80 to 10 g/25 mm. The resin constituting this layer (B) may have the above-mentioned characteristics, and specifically, polyethylene resin is preferable. Examples of this polyethylene resin include high-density polyethylene, medium-density polyethylene, and low-density polyethylene, and in addition to ethylene homopolymers, ethylene-α-olefin copolymers,
These include random or block copolymers such as ethylene-unsaturated carboxylic acid copolymers, or mixtures thereof. Here, high-density polyethylene has a density of 0.940 to 0.970 g/ ^cm3 , and medium- and low-density polyethylenes include high-pressure polyethylene, ethylene, propylene, and butene obtained by medium- and low-pressure methods.
Copolymers with α-olefins having 3 to 12 carbon atoms such as 1,4-methylpentene-1 and octene-1,
So-called linear low-density polyethylene (LLDPE)
There is. When these polyethylene resins are used as a component of layer (B), the melt index of this polyethylene resin is usually 0.02 to 10.0 g/
10 minutes, preferably 0.03 to 5.0 g/10 minutes, more preferably 0.04 to 2.0 g/10 minutes. If the melt index of the polyethylene resin is outside the above range, it is unfavorable in terms of melt kneading properties, moldability, etc. In addition, resins other than polyethylene resin include polyester resin, polycarbonate resin,
Examples include polyamide resin. The first invention is a multilayer material that essentially includes at least two layers, the (A) layer and the (B) layer as described above. Next, the multilayer material of the second invention is constructed by laminating layer (C) in addition to the above layers (A) and (B) with an adhesive resin layer interposed therebetween. This (C) layer is stacked on the (A) layer side, that is, so that the (A) layer faces the (C) layer. Any known gas barrier resin can be used as a component of this (C) layer. Specifically, ethylene-
Preferred examples include saponified vinyl acetate copolymers, polyamides, polyesters, polyacrylonitrile, and polyvinylidene chloride. Various adhesive resin layers can be used between layer (C) and layer (A), but usually modified polyolefin, such as unsaturated carboxylic acid or its derivative modified polyolefin (product name: Polytack), is used. etc.), metal salts of ethylene-acrylic acid copolymers (ionomers, etc.), and mixtures of these and unmodified olefins. In the multilayer material of the present invention, in the first invention (A)
In the second invention, the essential component layers are the (B) layer, the (A) layer, the adhesive resin layer, and the (C) layer. In addition to this, other layers can be laminated as desired. Here, there are no particular restrictions on other layers that may be laminated as desired;
For example, in the case of the second invention, preferable examples include polypropylene and a composition having the same components as the layer (A). These layers are laminated on the (C) layer side, and are usually laminated via a suitable adhesive resin layer as described above. In the second invention, for example, when a layer similar to layer (A) ((A') layer) is used as another layer, layer (B), (A)
layer, adhesive resin layer, (C) layer, adhesive resin layer, (A′)
A multilayer body is formed in which six of the layers are stacked one after the other. The thickness of each of the above layers may be determined by considering the purpose of use of the multilayer material of the present invention, but when manufacturing multilayer sheets or multilayer films for forming various ordinary packaging containers, etc. The thickness of the entire body is the first
20 to 2000μ for both the invention and the second invention, preferably 30 to 200μ
A suitable thickness is 1200μ, particularly for the layer (B), about 2 to 300μ, preferably about 5 to 150μ. There are no particular restrictions on the molding method used to mold multilayer bodies such as multilayer sheets and films, various packaging materials, and containers using the multilayer material of the present invention. An extrusion molding method is preferred, and more specifically, an inflation method using a circular die and a T-die coextrusion method using a flat die are applied. [Effects of the Invention] According to the present invention as described above, a multilayer material of any thickness can be manufactured easily and hygienically by coextrusion method etc., and furthermore, by specifying the components constituting each layer (A The interlayer peel strength between layer ) and layer (B) can be set arbitrarily. Furthermore, the multilayer material of the present invention has excellent heat resistance, chemical resistance, etc. Therefore, it can be used as a packaging material for aseptic packaging by heat sterilizing it during multilayer molding or container molding. In particular, when filling a container made of the multilayer material of the present invention with food, it can be used more hygienically if the non-fusible resin layer (B) is peeled off immediately before filling the container. According to the second invention, by further laminating a gas barrier resin layer on the multilayer material of the first invention, it is possible to manufacture a packaging material particularly suitable for long-term storage of foods, beverages, and the like. Therefore, the easily peelable multilayer material of the present invention is useful as a packaging material for various kinds of foods, pharmaceuticals, medical instruments, precision parts, and the like. [Example] Next, the present invention will be explained in more detail by giving specific examples. Example 1 The low crystallinity ^α- Layer (A) containing a predetermined amount of olefin copolymer and low density polyethylene (density 0.921g/
cm ³ , melt index 0.6 g/10 min, manufactured by Toyo Soda Kogyo Co., Ltd., product name: Petrocene 175) layer (B)
Co-extruded, (A) layer thickness 250μ, (B) layer thickness
A multilayer sheet consisting of two 50μ layers was produced. Table 1 shows the interlayer peelability and adhesion between layer (A) and layer (B) of this sheet. Example 2 Low-density polyethylene (same as Example 1) as a component of layer (B), polypropylene resin (same as Example 1) as a component of layers (A) and (A'), and low crystallinity as shown in Table 1. A composition containing a predetermined amount of a polyolefin copolymer, maleic anhydride-modified polypropylene (melt index 4 g/10 minutes, manufactured by Idemitsu Petrochemical Co., Ltd.) as a component of the (D) layer and (D') layer. Product name: Idemitsu Polytac E100), saponified ethylene-vinyl acetate copolymer as a component of layer (C) (melt index 1.3 g/10 minutes, ethylene content 32 mol%, manufactured by Kuraray Co., Ltd., product name: EVAL EP-F101)
Using (B) layer, (A) layer, (D) layer, (C) layer, (D′) layer,
The layers (A') were laminated in this order to obtain a multilayer sheet consisting of 6 layers and 4 components. In addition, the thickness of each layer is in the order mentioned above.
They were 50μ, 340μ, 20μ, 30μ, 20μ, and 340μ. A ribbed container (diameter 60 mm, height 25 mm) was formed from the obtained sheet by pressure forming. (A) of this container
Table 1 shows the interlayer peelability and adhesion between the layer and the (B) layer. Note that peelability and adhesiveness were evaluated based on the following criteria. ◎...Very good 〇...Good △...Slightly poor ×...Poor [Table]

Claims (1)

[Scope of Claims] 1 (A) A polypropylene resin composition layer comprising 100 parts by weight of a polypropylene resin and 0.5 to 3 parts by weight of a low-crystalline α-olefin copolymer, and (B)
An easily peelable multilayer material comprising at least two layers of the polypropylene resin and a non-fusible resin layer. 2 The low crystalline α-olefin copolymer is an ethylene-propylene copolymer, an ethylene-propylene-diene copolymer, or an ethylene-butene-1
The easily peelable multilayer material according to claim 1, which is any copolymer. 3. The easily peelable multilayer material according to claim 1, wherein (B) the resin layer that is non-fusible with the polypropylene resin is a polyethylene resin layer. 4 (A) A polypropylene resin composition layer comprising 100 parts by weight of a polypropylene resin and 0.5 to 3 parts by weight of a low-crystalline α-olefin copolymer, and (B)
A gas barrier resin layer (C) is placed on the (A) polypropylene resin composition layer side of the multilayer material consisting of at least two resin layers that are non-fusible with the polypropylene resin via an adhesive resin layer. An easily peelable multilayer material formed by forming. 5 The low crystallinity α-olefin copolymer is an ethylene-propylene copolymer, an ethylene-propylene-diene copolymer, or an ethylene-butene-1
The easily peelable multilayer material according to claim 4, which is any copolymer. 6. The easily peelable multilayer material according to claim 4, wherein (B) the resin layer that is non-fusible with the polypropylene resin is a polyethylene resin layer.