JPH0458788B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a resin laminate, and more specifically, it has improved impact resistance, heat resistance, punching property, and stretchability during thermoforming, and can be used for various foods, for example,
The present invention relates to a resin laminate that can be used as a packaging material suitable for packaging beverages, medicines, etc. [Prior Art] Conventionally, paper, synthetic resin sheets, synthetic resin films, laminates of paper and synthetic resin sheets or films, etc. have been used as packaging materials for various foods, beverages, medicines, etc. . Among these, synthetic resin packaging materials, particularly polyolefin sheets or polyolefin films, are used in many industrial fields because they have excellent moldability, high productivity, water resistance, chemical resistance, etc. However, this material has the disadvantage that its rigidity and heat resistance are insufficient. Furthermore, if a protrusion is provided on the polyolefin film or if the polyolefin film comes into contact with a protrusion, the polyolefin film is easily damaged. Therefore, in order to solve this problem, a relatively large amount (for example, 20 to 80% by weight) of an inorganic filler such as talc or calcium carbonate is blended into polyolefin resin, and the resulting resin composition is formed into a sheet. It is possible that This resin exhibits excellent physical properties such as rigidity and heat resistance, and is easy to incinerate and is well known as a pollution-free resin. By the way, this product can be used as food packaging containers such as trays by vacuum forming or compression molding, but when extruding the sheet material, die lines may occur or the surface may become rough. Alternatively, it is necessary to consider safety due to elution of the inorganic filler during use, and furthermore, there are problems with moldability itself. For this reason, a polyolefin resin layer containing substantially no inorganic filler or only a specific amount of inorganic filler is formed on both sides of the rigid resin layer in which inorganic filler is dispersed. A resin laminate has been proposed that is formed into a three-layer sheet. Specifically, for example, in JP-A No. 52-63283, a material obtained by blending an inorganic filler with a polyolefin resin is used as a center layer, and both sides of the material are sandwiched between polyolefin resins. A laminated plastic sheet is described, and a similar one is also described in JP-A-55-154159. Further, JP-A-57-15963 also describes a similar multilayer sheet. [Problems to be Solved by the Invention] Such a conventional resin laminate is shown in FIG.
In FIG. 2, 1 is a resin layer containing a filler, and 2 is a polyolefin layer covering this resin layer. However, since such a three-layer resin laminate contains a large amount of inorganic filler relative to the total resin component, properties such as impact resistance, heat resistance, and thermoformability deteriorate. Furthermore, if rubber or the like is blended into the outer layer resin in order to improve the impact resistance of this resin laminate, there is a drawback that punching properties (cutting properties) are reduced. Here, punching property refers to the property of punching out a molded product from a molded sheet.
This is an indicator of ease of cutting and the absence of stringiness. [Objective of the Invention] The object of the present invention is to provide a resin molded product (for example, a flat sheet-like molded product) for molding a final product with good surface smoothness, impact strength, heat resistance, and cold resistance. The object of the present invention is to provide a resin laminate having excellent properties and stretchability during thermoforming. [Means for achieving the object of the invention] The gist of this invention for achieving the above object is as follows:
A first layer made of a polyolefin resin mixed with an inorganic filler is laminated on both sides of a central layer containing a polyolefin resin, and a second layer containing a polyolefin resin is further formed on the outside of each of the first layers. This is a resin laminate characterized by forming. FIG. 1 shows the configuration of this invention. In Figure 1, 3
4 indicates the central layer, 4 indicates the 1st layer and 5
The second layer is indicated by . The center layer is made of at least a polyolefin resin. Here, the polyolefin serving as the base polymer of the polyolefin resin includes polyethylene such as high-density polyethylene, medium-, low-density polyethylene, and linear low-density polyethylene, isotactic polypropylene, syndiotactic polypropylene, atactic polypropylene, etc. Examples include polypropylene, polybutene, poly-4-methylpentene-1, and the like. In addition, in this invention, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer,
Copolymers of olefins and other vinyl monomers, such as ethylene-vinyl chloride copolymers and propylene-vinyl chloride copolymers, can also be used. Furthermore, in this invention, a modified polyolefin can also be used as the polyolefin. Examples of the modified polyolefin include those obtained by chemically modifying polyolefin with an unsaturated carboxylic acid (including its anhydride) or a derivative thereof. Here, an elastomer such as polybutadiene can also be added during modification. In producing this chemically modified polyolefin, a polyolefin such as polypropylene, an unsaturated carboxylic acid, or a derivative thereof may be reacted with a radical generator. Among the various polyolefins, polyethylene, polypropylene, polybutene-1, and polymethylpentene-1 are preferred, and polypropylene or a mixture of polypropylene and polyethylene is particularly preferred. Furthermore, if the desirable physical properties of polyolefins are shown, they are methytoflow index (MI)
However, 0.2-20g/10 minutes, preferably 2.0-10.0g/
It's 10 minutes. This center layer is mainly formed of the above-mentioned polyolefin resin, but in order to further improve the impact resistance of this resin laminate, low-crystalline or non-crystalline resin, ethylene-propylene rubber (EPR) is used. , ethylene-propylene-diene (EPDM) or the like is preferably contained in the center layer. Next, the first layer is made of polyolefin resin and
80% by weight, particularly preferably 30 to 65% by weight of inorganic filler. The base polymer of the polyolefin resin for forming this first layer is the same as that for the center layer. Preferred base polymers are polyethylene, polypropylene and blends thereof. Note that EPR and EPDM are included in this first layer.
may be blended, but the purpose of this invention can be achieved even without blending, so the first
There is no particular need to incorporate such a rubber into the layer. The amount of inorganic filler blended in this first layer is important. If the amount of inorganic filler added is less than 20% by weight, heat resistance and mechanical strength will decrease, and the burned calories of the resin laminate will increase, leading to damage and malfunction of the incinerator. In addition, when the amount is more than 80% by weight, the mechanical strength of this resin laminate increases.
This results in a decrease in moldability. Examples of the inorganic filler include carbonates such as calcium carbonate, magnesium carbonate, and dolomite; sulfates such as calcium sulfate, magnesium sulfate, and barium sulfate; sulfites such as calcium sulfite; talc, clay, mica, asbestos, and glass. Silicates or silicate minerals such as fibers, glass beads, calcium silicate, montmorillonite, and bentonite; Metal powders such as iron, zinc, and aluminum; Metal oxides such as titanium oxide and aluminum oxide; Metals such as aluminum hydroxide Examples include hydroxides; ceramics such as silicon carbide and silicon nitride, and their whiskers; carbon black, graphite, carbonate fibers, and the like. These inorganic fillers may be used alone or in combination of two or more of the above inorganic fillers. Among the various inorganic fillers, talc, carbonates and metal oxides are preferred, and titanium oxide is preferred as the metal oxide, and calcium carbonate is preferred as the carbonate. Furthermore, among the various inorganic fillers mentioned above, talc,
titanium oxide, carbon black, graphite,
Using carbonated fibers, etc. can improve the light-shielding properties of this resin laminate, and packaging foods, medicines, etc. with such resin laminates prevents the packaged items from deteriorating due to light and can be stored for a long time. can be made possible. The inorganic filler may be in the form of particles, plates, or fibers, but in the present invention, the particle size is 20 μm or less, preferably 15 μm or less. In this invention, a second layer of polyolefin resin is laminated and formed on the outside of the first layer made by blending the inorganic filler and polyolefin resin.
As the polyolefin resin used at this time, the same base polymer as that for the center layer can be used. Preferred base polymers include polypropylene, polyethylene, linear low density polyethylene,
One or more ethylene-vinyl acetate copolymers are selected, and particularly preferred are polyethylene, polypropylene, and blends thereof. This invention has a great advantage in that the resin used for the second layer can be freely selected for punchability, sealability, printability, etc. without considering impact resistance. As mentioned above, the resin laminate according to the present invention has the following features:
A product having at least a five-layer structure, in which a first layer containing a specific amount of inorganic filler is laminated on each outer surface of a central layer, and a second layer is further laminated on each outer surface of the first layer. It is. The resin laminate according to the present invention generally has a total diameter of 50 to 3000 μm, and a more easily handled form has a diameter of 100 μm.
It is preferable to mold to a thickness of ~2000 μm. The thickness of each layer of this resin laminate cannot be uniformly determined depending on its use, but for example, the thickness ratio is 2nd layer: 1st layer: center layer: 1st layer: 2nd layer. Approximately 5-10:32-42:5-6:32
When the ratio is about 42:5 to 10, it is easy to obtain general-purpose properties of this resin laminate. This resin laminate can be manufactured by a coextrusion method. In addition, this central layer, the first layer and the second layer,
Elastomers such as EPR and EPDM; sparingly soluble azo dyes, red colorants, cadmium yellow,
Coloring agents such as cream yellow and titanium white; antioxidants such as triazole type, salicylic acid type, and acrylonitrile type; plasticizers such as phthalic acid diester, butanol diester, and phosphoric acid diester; heat stabilizers, etc. should be added and blended as appropriate. I can do it. [Examples] Hereinafter, the configuration and effects of the present invention will be explained in more detail and concretely using Examples. Example 1 Resin composition A and resin composition B consisting of the following components were molded using a feedblock type coextrusion molding machine to form a five-layer thickness consisting of each layer of A-B-A-B-A. A 0.8 mm sheet was obtained. Note that the thickness ratio of each layer of A:B:A:B:A at this time was 5:42:6:42:5. {Resin composition A} High-density polyethylene (density 0.963 g/cm ³ , MI=
0.25g/10min, product name 520MB, manufactured by Idemitsu Petrochemical Co., Ltd.)
60% by weight and polypropylene (density 0.91g/cm ³ ,
MI=0.6g/10min, product name E-100G, Idemitsu Petrochemical
Co., Ltd.) 40% by weight. {Resin Composition B} A blend of 40% by weight of the resin composition A, 56% by weight of talc (average particle size 14 μm), and 4% by weight of titanium oxide. A container with a development magnification of 3 was molded from the sheet obtained as described above by air-pressure thermoforming, and the moldability was good without any trouble, and the wall pressure distribution of the molded container was also good. , it had a paper-like texture. The tensile strength, tensile modulus, elongation, impact strength, tensile impact strength, and moisture permeability of the sheet before container molding were measured, and the results are shown in Table 1. Comparative Example 1 Example 1 except that instead of the center layer and the pair of first layers in Example 1, the center layer 2 was formed with resin composition A, resulting in three layers of A-B-A as a whole. A sheet was obtained in the same manner as above. This sheet was subjected to the same tests as in Example 1, and the results are shown in Table 1. Example 2 Resin C and resin compositions D and E consisting of the following components were molded into five layers of three types each consisting of C-D-E-D-C using a feedblock coextrusion molding machine. A sheet with a thickness of 0.8 mm was obtained. The thickness ratio of C:D:E:D:C in the sheet was 5:42:6:42:5. This sheet was tested in the same manner as in the previous example, and the results are shown in Table 1. {Resin C} Polypropylene (density 0.91g/cm ³ , MI=2.0
g/10 minutes, product name F-200S, manufactured by Idemitsu Petrochemical Co., Ltd.) {Resin composition D} 40% by weight of polypropylene (product name E-100G, above) and polyethylene (density 0.934 g/cm ³ , MI=
3.0g/10 minutes, product name Petrocene 219, Toyo Soda Kogyo
Co., Ltd., 10% by weight and talc (average particle size 14μm) 47
% by weight and 3% by weight of titanium oxide. {Resin composition E} Polypropylene (product name E-100G, above) 92% by weight, EP rubber (propylene content: 22% by weight, density 0.86g/cm ³ , MI = 3.6g/10min, Muny viscosity 70ML) ₁₄ (100℃) and 8% by weight. Comparative Example 2 The same procedure as in Example 2 was carried out except that the intermediate D-E-D layer in Example 2 was changed to the D layer, and two types and three layers of C-D-C were used. Test results for sheets obtained in the same manner as in the other examples are summarized in Table 1.

[Table] As can be understood from the results in the table, the resin laminates obtained according to the present invention have improved elongation, Dupont impact strength, and tensile impact strength compared to those of the comparative examples. [Effects of the Invention] As described above, the resin laminate according to the present invention has significantly improved properties in terms of elongation, Dupont impact strength, and tensile impact strength, as well as tensile strength and
It has excellent mechanical properties with tensile modulus maintained at the conventional level. Furthermore, the resin laminate according to the present invention has a specific amount of inorganic filler blended in the first layer, and
This is presumably due to the layered structure, which allows the sheet-like material to have the feel of paper even though it is made of synthetic resin. In addition, impact resistance, punching properties, sealing properties, printability, etc. can be improved depending on each component. When a rubber component or a soft resin is blended into the center layer, stretchability during thermoforming is good. Note that the resin laminate according to the present invention may be used not only as a thermoforming sheet but also as a bag-making film or a hollow container obtained by blow molding.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a five-layer resin laminate formed according to the present invention, and FIG. 2 is a sectional view of a conventional three-layer resin laminate. 1...Resin layer blended with a filler, 2...Polyolefin layer, 3...Center layer, 4...Polyolefin resin layer blended with a filler, 5...Polyolefin resin layer.

Claims (1)

[Claims] 1. A first layer made of a polyolefin resin mixed with an inorganic filler is laminated on both sides of a central layer containing a polyolefin resin, and a polyolefin resin is further layered on the outside of each of the first layers. A resin laminate comprising a second layer containing resin. 2. The resin laminate according to claim 1, wherein the center layer is formed by blending 30% by weight or less of ethylene-propylene rubber and/or ethylene-propylene-diene rubber with a polyolefin resin. 3 The first layer has an inorganic filler content of 20 to
The resin laminate according to claim 1 or 2, which has a content of 80% by weight.