Polyolefin sheets, press-through package base materials and press-through package packaging materials

Abstract

To provide a polyolefin-based sheet having sufficient moisture resistance, transparency and impact resistance, and further having excellent interlayer adhesive strength without a need for an adhesive layer.SOLUTION: There is provided a polyolefin-based sheet comprising at least two layers, a layer (A) containing a polypropylene-based resin (a) as a main component and a layer (B) containing a polyethylene-based resin (b) adjacent to the layer (A) as a main component, in which at least one thermoplastic resin (c) selected from a group consisting of petroleum resins, terpene resins, chroman-indene resins, rosin-based resins, and hydrogenated derivatives thereof, is included in at least one of the layer (A) and the layer (B), and an interlayer strength between the layer (A) and the layer (B) measured based on JIS K6854-3 method is 3.5 N / 15 mm or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyolefin sheet having excellent secondary processability, moisture resistance and transparency, and a press-through package base material and press-through package material made using the same. [Background technology]

[0002] In the pharmaceutical and food packaging fields, PTP (press-through package) packaging is used to package solid drugs such as capsules and tablets, granular foods, etc. In the food packaging field, blister packages, which are very similar to PTP packages, are also often used to package foods.

[0003] PTP packaging is a type of packaging in which a pocket for storing a solid agent such as a capsule is formed, for example, by applying pressure forming, vacuum forming, etc. to a transparent sheet, and after storing the capsule in the pocket, a foil or film made of a material that can be easily torn or opened by hand, such as aluminum foil, is laminated as a lid material to integrate the two. With PTP packaging, the solid agent or food stored in the pocket of the transparent sheet can be directly confirmed with the naked eye before opening, and when opening, the contents can be easily removed by pressing the solid agent in the pocket with a finger to break the lid material.

[0004] A blister package is a type of packaging in which a pocket is formed in accordance with the shape of the food product by vacuum forming a sheet or the like, and the food product or other contents are placed in this pocket, which is then sealed with heat-sealable coated paper or film.

[0005] Polyvinyl chloride (hereinafter sometimes referred to as "PVC") has traditionally been used as the raw material for sheets used in PTP packaging and blister packages because of its good thermoformability, rigidity at room temperature, impact resistance, and transparency. However, PVC generates hydrogen chloride gas depending on the combustion method, which can cause problems such as deterioration of the combustion furnace and environmental pollution, and its moisture resistance is also insufficient, so there has been a demand for an alternative material to PVC from the perspective of long-term storage of contents.

[0006] Therefore, polypropylene resin (hereinafter sometimes referred to as "PP") is generally used as an alternative material to PVC. For example, Patent Document 1 proposes a resin sheet made of PP and hydrogenated petroleum resin, which has good transparency and moisture resistance and is suitable for PTP packaging.

[0007] However, although PP has superior moisture resistance to PVC, in recent years, there has been a demand for further improvement in moisture resistance. Thus, cyclic polyolefin resins (hereinafter also referred to as "cyclic PO resins"), which are not only superior in moisture resistance but also have transparency and viscoelastic behavior similar to PVC, have attracted attention as one of the candidate materials to replace PVC and PP, and Patent Document 2 proposes a sheet using PP and polyethylene resins (hereinafter also referred to as "PE") for both surface layers and a cyclic PO resin for an intermediate layer, but there are problems in that the adhesion between the intermediate cyclic PO resin layer and both surface layers is poor, and the cyclic PO resin is less flexible than PP or PE, resulting in inferior impact resistance and high costs. Patent document 3 proposes a laminated sheet of PP and bio-PE using bio-PE (bio-polyethylene resin), which has higher moisture resistance than PP. However, the adhesion between the PP layer and the PE layer is poor, making it necessary to use an adhesive layer, which increases productivity and costs. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 6-99604 [Patent Document 2] JP 2010-194751 A [Patent Document 3] Patent No. 6355243 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention solves the above problems. Since PTP packaging is used for carrying or taking medicines in small portions, it is required to maintain the efficacy of the medicine, be visible, and have a certain degree of strength against impact, so moisture resistance, transparency, and impact resistance are important.

[0010] In view of the problems with the conventional technology, the object of the present invention is to provide a polyolefin-based sheet having sufficient moisture resistance, transparency and impact resistance, and further having excellent interlayer adhesion without requiring an adhesive layer, and a PTP packaging base material and a PTP packaging material made using the same. [Means for solving the problem]

[0011] Means for Solving the Problems The present inventors conducted intensive research to solve the above problems and discovered that the above problems can be solved by incorporating a specific thermoplastic resin into a layer mainly composed of a polypropylene-based resin and a layer mainly composed of a polyethylene-based resin, thereby completing the present invention.

[0012] That is, the present invention relates to a polyolefin-based sheet comprising at least two layers, namely, a layer (A) containing a polypropylene-based resin (a) as a main component, and a layer (B) adjacent to the layer (A) and containing a polyethylene-based resin (b) as a main component, wherein at least one of the layers (A) and (B) contains at least one thermoplastic resin (c) selected from the group consisting of petroleum resins, terpene resins, chroman-indene resins, rosin-based resins, and hydrogenated derivatives thereof, and wherein the interlaminar strength between the layers (A) and (B) measured in accordance with JIS K6854-3 is 3.5 N / 15 mm or more. Effect of the Invention

[0013] INDUSTRIAL APPLICABILITY According to the present invention, the polyolefin-based sheet of the present invention has excellent moisture resistance, transparency and impact resistance, and therefore can be suitably used for various packaging applications, and can be suitably used in particular as a base material for PTP packaging. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram for explaining the PTP molded product used in the examples described later. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A polyolefin sheet will be described below as an example of an embodiment of the present invention, although the scope of the present invention is not limited to the embodiment described below.

[0016] In this specification, the term "main component" refers to a component that occupies the largest mass ratio in the composition, and its content is preferably 45 mass% or more, more preferably 50 mass% or more, and even more preferably 55 mass% or more. Furthermore, when it is written "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", as well as "preferably larger than X" and "preferably smaller than Y".

[0017] The polyolefin-based sheet of the present invention comprises at least two layers: a layer (A) containing a polypropylene-based resin (a) as a main component, and a layer (B) adjacent to the layer (A) containing a polyethylene-based resin (b) as a main component, and at least one of the layers (A) and (B) contains a thermoplastic resin (c).

[0018] <About Layer (A)> The layer (A) is formed from a resin composition containing a polypropylene resin (a) as a main component. Each component contained in the resin composition will be described below.

[0019] [Polypropylene resin (a)] The polypropylene-based resin (a) used in the present invention may be a polypropylene having a single composition, i.e., a propylene homopolymer, or may be a random copolymer or a block copolymer in which propylene is copolymerized with a copolymerization component. The polypropylene-based resin (a) may be used alone or in combination of two or more kinds.

[0020] The copolymerization component is typically, for example, ethylene or 1-butene, with ethylene being preferred.

[0021] When the copolymer is used, the content of the copolymer component in the copolymer is preferably 0.5% by mass to 5.0% by mass, more preferably 1.0% by mass to 4.0% by mass, and even more preferably 1.5% by mass to 3.0% by mass. By keeping the content of the copolymer component in the copolymer within the above range, it is possible to impart suitable moisture resistance and transparency to the sheet while maintaining good film-forming properties.

[0022] As the polypropylene-based resin used in the present invention, from the viewpoint of being able to impart suitable moisture resistance and transparency to the sheet while maintaining good film-forming properties, a single-component polypropylene or a propylene-ethylene copolymer is preferred, a single-component polypropylene or a propylene-ethylene random copolymer is more preferred, and a propylene-ethylene random copolymer is particularly preferred.

[0023] The melt flow rate (hereinafter also referred to as "MFR") of the polypropylene resin (a) at 230°C under a load of 2.16 kg according to the JIS K7210 method is preferably 0.3 g / 10 min to 20 g / 10 min, more preferably 0.5 g / 10 min to 10 g / 10 min, and even more preferably 0.8 g / 10 min to 8.0 g / 10 min. If the MFR is within the above range, stable film formability is obtained, and a polyolefin sheet having good mechanical properties is obtained.

[0024] The polypropylene resin (a) must be contained as a main component of the resin composition forming the layer (A). When the resin composition forming the layer (A) is taken as 100% by mass, the lower limit of the content of the polypropylene resin (a) is preferably 45% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more. The upper limit of the content is not particularly limited, but is preferably 93% by mass or less. By making the content of the polypropylene resin (a) equal to or more than the lower limit, the moisture resistance and transparency of the sheet can be maintained, and by making it equal to or less than the upper limit, the film-forming property and thermoformability of the sheet can be improved.

[0025] The resin composition forming the layer (A) preferably contains a thermoplastic resin (c) from the viewpoint of adhesion to the layer (B).

[0026] [Thermoplastic resin (c)] The thermoplastic resin (c) is at least one selected from the group consisting of petroleum resins, terpene resins, chroman-indene resins, rosin resins, and hydrogenated derivatives thereof. The thermoplastic resin (c) is preferably compatible with the polypropylene resin (a) and has a higher glass transition temperature than the polypropylene resin (a).

[0027] Examples of the petroleum resin include petroleum resins such as C5-based petroleum resins, C9-based petroleum resins, C5-C9 copolymer-based petroleum resins, alicyclic hydrocarbon-based petroleum resins such as dicyclopentadiene-based petroleum resins, and hydrogenated derivatives thereof. Among these, hydrogenated derivatives of C9-based petroleum resins are preferred.

[0028] Examples of the terpene resin include terpene resins such as α-pinene polymers, β-pinene polymers, and dipentene polymers, and modified terpene resins such as terpene phenol resins, styrene-modified terpene resins, and hydrogenated terpene resins.

[0029] The coumarone-indene resin may be, for example, a thermoplastic synthetic resin obtained by purifying a 160 to 180° C. fraction of tar and polymerizing it with coumarone having 8 carbon atoms and indene having 9 carbon atoms as main monomers.

[0030] Examples of the rosin-based resin include unmodified rosins such as tall rosin, gum rosin, and wood rosin, polymerized rosin, disproportionated rosin, hydrogenated rosin, maleic acid-modified rosin, and fumaric acid-modified rosin, as well as esterified rosin resins obtained by modifying these with glycerin, pentaerythritol, ethylene glycol, or the like.

[0031] As the thermoplastic resin (c), from the viewpoint of exhibiting relatively good compatibility when mixed with the polypropylene-based resin (a) and further improving color tone, thermal stability, compatibility, moisture impermeability, etc., hydrogenated derivatives are preferred, and in particular, petroleum resins or terpene resins having a hydrogenation rate (hereinafter referred to as "hydrogenation rate") of 95% or more and substantially free of polar groups such as hydroxyl groups, carboxy groups, and halogens, or unsaturated bonds such as double bonds, are preferred, with petroleum resins being particularly preferred. Note that "substantially free" means that the content of the polar groups and unsaturated bonds is 3% or less, preferably 1% or less, relative to the thermoplastic resin (c).

[0032] The softening point of the thermoplastic resin (c) is preferably 80 to 170°C, more preferably 90 to 160°C, and particularly preferably 100 to 150°C. When the softening point of the thermoplastic resin (c) is within the above range, the thermoplastic resin (c) is easily compatible with the polypropylene resin (a), and the formation of fine crystals due to the crystallization of the polypropylene resin (a) is more promoted, and a polyolefin sheet with excellent transparency tends to be obtained. In addition, when the softening point is above the above lower limit, blocking of the raw material pellets is prevented during sheet formation, and productivity tends to be good.

[0033] Specific examples of thermoplastic resins (c) include the "Petrotack" series manufactured by Tosoh Corporation, the "Alcon" series manufactured by Arakawa Chemical Industries, Ltd., the "Clearon" series manufactured by Yasuhara Chemical Co., Ltd., the "Imarve" series manufactured by Idemitsu Petrochemical Co., Ltd., and the "T-REZ" series manufactured by JXTG Energy Corporation.

[0034] The content of the thermoplastic resin (c) is preferably 7% by mass or more and 40% by mass or less, more preferably 8% by mass or more and 30% by mass or less, and even more preferably 9% by mass or more and 25% by mass or less, when the resin composition forming the layer (A) is taken as 100% by mass. By making the proportion of the thermoplastic resin (c) equal to or more than the above lower limit, the transparency and moisture resistance of the sheet tend to be improved. In addition, by making the proportion of the thermoplastic resin (c) equal to or less than the upper limit, good film-forming properties and impact resistance can be maintained, and sufficient interlayer strength can be obtained when the sheet is laminated.

[0035] [Other additives] In addition, the resin composition forming the layer (A) may contain polyolefin resins other than the polypropylene resin (a), polystyrene resins, polyester resins, polyolefin or polystyrene thermoplastic elastomers, and other resins, as well as additives such as crystal nucleating agents, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, nucleating agents, antibacterial and antifungal agents, antistatic agents, and lubricants, within the scope of the present invention. These may be used alone or in combination of two or more. Among these, crystal nucleating agents are preferred because they can improve the transparency and moisture resistance of the polyolefin sheet.

[0036] Examples of the crystal nucleating agent include dibenzylidene sorbitol (DBS) compounds, 1,3-O-bis(3,4 dimethylbenzylidene) sorbitol, dialkylbenzylidene sorbitol, diacetals of sorbitol having at least one chlorine or bromine substituent, di(methyl- or ethyl-substituted benzylidene) sorbitol, bis(3,4-dialkylbenzylidene) sorbitol having a substituent forming a carbon ring, aliphatic, alicyclic, and aromatic carboxylic acids, dicarboxylic acids, or polybasic polycarboxylic acids, and anhydrides and metal salts thereof, etc. metal salt compounds of organic acids, cyclic bis-phenol phosphates, bicyclic dicarboxylic acids and salt compounds such as disodium bicyclo[2.2.1]heptene dicarboxylate, etc., saturated metal or organic salt compounds of bicyclic dicarboxylates such as bicyclo[2.2.1]heptane dicarboxylate, etc., 1,3:2,4-O-dibenzylidene-D-sorbitol, 1,3:2,4-bis-O-(m-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-ethyl ... 1,3:2,4-bis-O-(m-propylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(m-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-methylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-isopropylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-propylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-isopropylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-propylbenzylidene)-D-sorbitol, ,3:2,4-bis-O-(pn-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,3-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,4-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,5-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3,4-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3,5-dimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,3-diethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,4-diethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,5-diethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3,4-diethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3,5-diethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,4,5-trimethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3,4,5-trimethyl benzylidene)-D-sorbitol, 1,3:2,4-bis-O-(2,4,5-triethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(3,4,5-triethylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-methyloxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-ethyloxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-isopropyloxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis- O-(on-propyloxycarbonylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(on-butylbenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(o-chlorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-(p-chlorobenzylidene)-D-sorbitol, 1,3:2,4-bis-O-[(5,6,7,8,-tetrahydro-1-naphthalene)-1-methylene]-D-sorbitol, 1,3:2,4-bis-O-[(5,6,7,8,-tetrahydro-2-naphthalene)-1-methylene ]-D-sorbitol, 1,3-O-benzylidene-2,4-Op-methylbenzylidene-D-sorbitol, 1,3-Op-methylbenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-Op-ethylbenzylidene-D-sorbitol, 1,3-Op-ethylbenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-Op-chlorobenzylidene-D-sorbitol, 1,3-Op-chlorobenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-(2,4-dimethylbenzylidene)-D-sorbitol, 1,3-O-(2,4-dimethylbenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O-(3,4-dimethylbenzylidene)-D-sorbitol, 1,3-O-(3,4-dimethylbenzylidene)-2,4-O-benzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene-2,4-Op-ethylbenzylidene sorbitol, 1,3-p-ethyl-benzylidene-2,4-p-methylbenzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene-2,4-Op-chlorobenzylidene-D-sorbitol, 1,3-Op-chloro- Diacetal compounds such as benzylidene-2,4-Op-methylbenzylidene-D-sorbitol, sodium 2,2'-methylene-bis-(4,6-di-tert-butylphenyl)phosphate, aluminum bis[2,2'-methylene-bis-(4-6-di-tert-butylphenyl)phosphate], sodium 2,2-methylenebis(4,6-di-tert-butylphenyl)phosphate, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecane acid, etc. Examples of the fatty acid include fatty acids such as myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, and montanic acid; fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, and hebenic acid amide; fatty acid metal salts such as magnesium stearate, zinc stearate, and calcium stearate; inorganic particles such as silica, talc, kaolin, and calcium carbide; higher fatty acid esters such as glycerol and glycerin monoester, and the like. These may be used alone or in combination of two or more. Among these, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, and hebenic acid amide, and fatty acid metal salts such as magnesium stearate, zinc stearate, and calcium stearate are particularly preferred.

[0037] Specific examples of crystal nucleating agents include the "Gelall D" series manufactured by New Japan Chemical Co., Ltd., the "Adeka STAB" series manufactured by Asahi Denka Kogyo Co., Ltd., the "HYPERFORM HPN-20E", "HL3-4", and "Millad" series manufactured by Milliken Chemical Co., Ltd., the "IRGACLEAR" series manufactured by BASF, and "Rikemaster CN-001" and "Rikemaster CN-002" manufactured by Riken Vitamin Co., Ltd. Among these, those that are particularly effective in improving transparency include "HYPERFORM HPN-20E" and "HL3-4" manufactured by Milliken Chemical Co., Ltd., and "Rikemaster CN-001" and "Rikemaster CN-002" manufactured by Riken Vitamin Co., Ltd.

[0038] The content of the crystal nucleating agent is preferably 0.5% by mass or more and 4% by mass or less, more preferably 1% by mass or more and 3.5% by mass or less, when the resin composition forming the layer (A) is taken as 100% by mass. By making the proportion of the crystal nucleating agent equal to or more than the lower limit, the crystallinity of the polyolefin sheet is improved, and suitable transparency and moisture resistance can be imparted. In addition, by making the proportion of the crystal nucleating agent equal to or less than the upper limit, the proportion of additives can be minimized, and an efficient effect can be expected.

[0039] The layer (A) of the polyolefin sheet of the present invention can be obtained by using the above-mentioned resin composition by the production method described below.

[0040] <About Layer (B)> The layer (B) is formed from a resin composition mainly composed of a polyethylene resin (b). Each component contained in the resin composition will be described below.

[0041] [Polyethylene resin (b)] The polyethylene resin (b) may be a polyethylene homopolymer, or a polyethylene copolymer, which is a copolymer of ethylene and a monomer component other than ethylene. Also, a mixture of these may be used as the polyethylene resin (b).

[0042] Examples of the monomer component other than ethylene include α-olefin monomers and non-olefin monomers having a functional group, and among these, α-olefin monomers are preferred.

[0043] The α-olefin monomer may be an α-olefin having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-2-propanediol ... Examples of the olefins include 1-butene, 4-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, and 12-ethyl-1-tetradecene. These may be used alone or in combination of two or more. Among these, propylene, 1-butene, 1-hexene, and 1-octene are preferred from the viewpoints of industrial availability, various characteristics, and economic efficiency.

[0044] When the above-mentioned α-olefin monomers are used as copolymerization components, the total proportion of the α-olefin monomers in the polyethylene copolymer is preferably 0.1 to 4 mass%, more preferably 0.3 to 3.5 mass%, and particularly preferably 0.5 to 3 mass%. When the proportion of the α-olefin monomers is within this range, the moisture resistance and transparency of the polyolefin-based sheet can be further improved.

[0045] As the polyethylene-based resin (b) used in the present invention, among the above, it is preferable to use an ethylene homopolymer or a copolymer of ethylene and at least one α-olefin monomer selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene.

[0046] The polymerization method for the polyethylene resin (b) is not particularly limited, and may be carried out by a conventional method. The catalyst used in the polymerization is also not particularly limited, and may be any of the conventional catalysts.

[0047] The polyethylene resin (b) used in the present invention has a density of 0.935 g / cm3 as measured according to JIS K7112. 3 It is preferable that the content is equal to or more than 0.94 g / cm. 3 More preferably, it is 0.945 g / cm 3 With the density in the above range, a sheet having high moisture resistance and chemical resistance can be provided. The upper limit of the density of the polyethylene resin (b) is usually 0.97 g / cm 3 It is.

[0048] The polyethylene resin (b) has an MFR of 0.3 g / 10 min to 20 g / 10 min under a load of 2.16 kg at 190° C. according to the JIS K7210 method, more preferably 0.5 g / 10 min to 10 g / 10 min, and even more preferably 0.8 g / 10 min to 8 g / 10 min. If the MFR is within the above range, stable film formability and a polyolefin sheet having good mechanical properties can be obtained.

[0049] The polyethylene resin (b) may be a petroleum-derived polyethylene resin, but is preferably a bio-polyethylene resin from the standpoint of environmental protection. The above-mentioned "biopolyethylene resin" means a polyethylene resin obtained by chemical or biological synthesis using renewable biomass resources as raw materials. The biopolyethylene resin has the characteristic that even if it is incinerated, it does not increase the carbon dioxide concentration in the atmosphere due to the carbon neutrality of biomass.

[0050] The biopolyethylene resin preferably uses plant-derived ethylene derived from bioethanol obtained from a plant raw material, i.e., the biopolyethylene resin is preferably a plant-derived polyethylene resin.

[0051] Specific examples of polyethylene resins (b) that are derived from petroleum include Asahi Kasei's Suntech HD series, Japan Polypropylene's Novatec HD series, and Prime Polymer's Evolue H series. Examples of biopolyethylene resins include Braskem's Green Polyethylene series.

[0052] The polyethylene resin (b) must be contained as a main component of the resin composition forming the layer (B). When the resin composition forming the layer (B) is taken as 100% by mass, the lower limit of the content of the polyethylene resin (b) is preferably 45% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more. The upper limit of the content is not particularly limited, but is preferably 93% by mass or less. By making the content of the polyethylene resin (b) equal to or more than the above lower limit, the sheet can be imparted with moisture resistance and impact resistance. Furthermore, by making the proportion of the polyethylene resin (b) equal to or less than the upper limit, the sheet can be imparted with appropriate rigidity.

[0053] The resin composition forming the layer (B) preferably contains a thermoplastic resin (c) from the viewpoint of adhesion to the layer (A).

[0054] [Thermoplastic resin (c)] Examples of the thermoplastic resin (c) contained in the resin composition forming the layer (B) include the thermoplastic resin (c) described in the layer (A). The thermoplastic resin (c) contained in the resin composition forming the layer (B) is preferably compatible with the polyethylene resin (b) and has a higher glass transition temperature than the polyethylene resin (b). The above thermoplastic resin (c) can be used alone or in combination of two or more. Among them, the thermoplastic resin (c) is preferably a hydrogenated derivative, which shows relatively good compatibility when mixed with the polyethylene resin (b) and further enhances color tone, thermal stability, compatibility, moisture resistance, etc., and is particularly preferably a petroleum resin or terpene resin having a hydrogenation rate (hereinafter referred to as "hydrogenation rate") of 95% or more and substantially does not contain polar groups such as hydroxyl groups, carboxy groups, and halogens, or unsaturated bonds such as double bonds, and is particularly preferably a petroleum resin.

[0055] The softening point of the thermoplastic resin (c) contained in the resin composition forming the layer (B) is also preferably within the range of the thermoplastic resin (c) explained in connection with the layer (A).

[0056] In the present invention, the types of thermoplastic resin (c) contained in the resin composition forming layer (A) and the thermoplastic resin (c) contained in the resin composition forming layer (B) may be the same or different. From the viewpoint of adhesion, it is preferable to use the same type of thermoplastic resin (c), and it is more preferable to use the same type of thermoplastic resin (c).

[0057] The content of the thermoplastic resin (c) is preferably 7% by mass or more and 40% by mass or less, more preferably 8% by mass or more and 30% by mass or less, and even more preferably 9% by mass or more and 25% by mass or less, when the resin composition forming the layer (B) is taken as 100% by mass. By making the proportion of the thermoplastic resin (c) equal to or more than the above lower limit, the transparency and moisture resistance of the sheet tend to be improved. In addition, by making the proportion of the thermoplastic resin (c) equal to or less than the upper limit, good film-forming properties and impact resistance can be maintained, and sufficient interlayer strength can be obtained when the sheet is laminated.

[0058] [Other additives] In addition, the resin composition forming the layer (B) may contain polyolefin resins other than the polyethylene resin (b), polystyrene resins, polyester resins, polyolefin or polystyrene thermoplastic elastomers, and other resins, as well as additives such as crystal nucleating agents, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, nucleating agents, antibacterial and antifungal agents, antistatic agents, and lubricants, within the scope of the present invention. These may be used alone or in combination of two or more. Among these, crystal nucleating agents are preferred because they can improve the transparency and moisture resistance of the polyolefin sheet.

[0059] As the crystal nucleating agent, the crystal nucleating agents explained in the layer (A) can be used, and the preferable crystal nucleating agents and the content thereof are also as explained in the layer (A).

[0060] <Method of manufacturing polyolefin sheet> Next, the method for producing the polyolefin sheet of the present invention will be described. The method for molding the polyolefin sheet of the present invention is not particularly limited. For example, the resin composition forming layer (A) and the resin composition forming layer (B) can be melt-mixed in a single-screw or twin-screw extruder, co-extruded through a T-die, and quenched and solidified with a cast roll to produce an unstretched sheet. Here, the term "unstretched sheet" refers to a sheet that is not actively stretched for the purpose of increasing the strength of the sheet. For example, the term "unstretched sheet" includes sheets that are stretched less than twice their original size by stretching rolls during extrusion molding.

[0061] The polyolefin-based sheet of the present invention thus obtained contains the thermoplastic resin (c) in at least one of the layers (A) and (B), and therefore has excellent adhesion between the layers (A) and (B). Therefore, there is no need to provide an adhesive layer between the layers (A) and (B), and the sheet can be excellent in productivity and cost. In particular, from the viewpoint of adhesion, it is preferable that the thermoplastic resin (c) is contained in both the layers (A) and (B).

[0062] The layer structure of the polyolefin sheet of the present invention is not particularly limited as long as it has at least a two-layer structure in which layer (A) is adjacent to layer (B). For example, the two-layer structure may further include layer (A) or layer (B), or may include another thermoplastic resin layer or adhesive layer. Among them, from the viewpoint of impact resistance, a two-kind three-layer structure in which layer (A) is adjacent to both sides of layer (B) is preferable.

[0063] [Thickness] The polyolefin-based sheet of the present invention has a total thickness of 50 μm or more and 600 μm or less, more preferably 100 μm or more and 500 μm or less, even more preferably 150 μm or more and 450 μm or less, and particularly preferably 200 μm or more and 400 μm or less. If the total thickness of the layer (A) and the layer (B) is equal to or more than the lower limit, the sheet exhibits suitable rigidity and has excellent processability and curl resistance. On the other hand, if the thickness of the propylene-based sheet of the present invention is equal to or less than the upper limit, the sheet rigidity can be controlled within a suitable range, so that when used as a PTP package, there is no problem in removing the drug, and excellent processability can be maintained.

[0064] In addition, the thickness of the polyolefin sheet of the present invention is not particularly limited, but taking into consideration processability and practicality, it is preferably 100 μm or more and 1000 μm or less, more preferably 150 μm or more and 800 μm or less, even more preferably 180 μm or more and 600 μm or less, and particularly preferably 200 μm or more and 400 μm or less.

[0065] In the polyolefin sheet of the present invention, the thickness ratio of the layer (A) to the layer (B) is preferably 1:1.2 to 1:5, more preferably 1:1.5 to 1:4, and particularly preferably 1:1.8 to 1:3. When the thickness ratio of the layer (A) to the layer (B) is within the above range, the sheet exhibits appropriate rigidity and tends to be excellent in processability and curl resistance. When the polyolefin sheet has a plurality of layers (A) and layers (B), the above thickness ratio is the ratio of the total thickness of all layers (A) to the total thickness of all layers (B).

[0066] In the polyolefin sheet of the present invention, when the total of the resin compositions of the layers (A) and (B) is taken as 100% by mass, the content of the thermoplastic resin (c) is preferably 7% by mass or more and 40% by mass or less, more preferably 8% by mass or more and 30% by mass or less, and particularly preferably 9% by mass or more and 25% by mass or less. When the content of the thermoplastic resin (c) is within the above range, the adhesion between the layers (A) and (B) tends to be excellent, and the impact resistance also tends to be excellent.

[0067] From the viewpoint of adhesion, the ratio of the thermoplastic resin (c) (% by mass) contained in 100% by mass of the resin composition of Layer (A) to the thermoplastic resin (c) (% by mass) contained in 100% by mass of the resin composition of Layer (B) [thermoplastic resin (c) contained in the resin composition of Layer (A):thermoplastic resin (c) contained in the resin composition of Layer (B)] is preferably 3:1 to 1:5, more preferably 2:1 to 1:4, and particularly preferably 1:1 to 1:3.

[0068] [Interlaminar strength] The polyolefin sheet of the present invention has an interlaminar strength between the layer (A) and the layer (B) of 3.5N / 15mm or more, preferably 4N / 15mm or more, and particularly preferably 5N / 15mm or more, measured according to JIS K6854-3. By making the interlaminar strength of the polyolefin sheet of the present invention equal to or more than the above-mentioned value, good adhesion between the layer (A) and the layer (B) can be obtained. In addition, when the polyolefin sheet has a plurality of two-layer structures of adjacent layers (A) and (B), it is sufficient that the interlaminar strength between at least one adjacent layer (A) and layer (B) is equal to or more than the above-mentioned value, and preferably, the interlaminar strength between all adjacent layers (A) and layers (B) is equal to or more than the above-mentioned value.

[0069] [Moisture resistance] The water vapor transmission rate of the polyolefin-based sheet of the present invention is 0.6 g / (m2) measured at a temperature of 40° C. and a relative humidity of 90% according to the JIS K7129-2 method. 2 24 hours) or less, and more preferably 0.55 g / (m 2 24 hours) or less, and more preferably 0.53 g / (m 2 By setting the water vapor transmission rate of the polyolefin-based sheet of the present invention to the above value, good moisture resistance can be obtained, and deterioration of the contents can be suppressed when the sheet is used for packaging medicines and the like.

[0070] [Transparency] When the polyolefin-based sheet of the present invention is used for packaging purposes, the haze measured according to JIS K7136 is preferably 50% or less, more preferably 45% or less, and even more preferably 40% or less, from the viewpoints of design, visibility of contents, etc. If the haze of the polyolefin-based sheet of the present invention is within the above range, sufficient visibility can be ensured.

[0071] [Impact resistance] The polyolefin sheet of the present invention preferably has a film embrittlement temperature measured according to the conditions and method of ASTM D1790 of less than 20° C., more preferably less than 0° C., and even more preferably less than −25° C. If the film embrittlement temperature of the polyolefin sheet of the present invention is within the above range, sufficient impact resistance can be ensured.

[0072] [Biomass ratio] The biomass ratio of the polyolefin-based sheet of the present invention is preferably 10% or more, more preferably 15% or more, and even more preferably 25% or more. If the biomass ratio of the polyolefin-based sheet of the present invention is equal to or greater than the above values, the environmental load can be reduced. The biomass ratio can be calculated by the following method. [How to calculate biomass ratio] "Biomass ratio of sheet" (%) = "Biomass ratio of resin made from biomass resources" (%) x "mass ratio of resin made from biomass resources in sheet"

[0073] <Molded body using polyolefin sheet> The polyolefin sheet of the present invention can be formed into molded articles of various shapes by vacuum forming, pressure forming, pressure vacuum forming, press forming, and other thermoforming methods, and can be suitably used to manufacture, for example, packaging molded articles, particularly packaging molded articles such as PTP packaging base materials and blister packages.

[0074] For example, when producing a molded sheet for a PTP packaging base material, the propylene-based sheet of the present invention is heated and softened with a heating plate before molding, the sheet is sandwiched in a mold, and compressed air is injected to mold a large number of pockets (e.g., about 9 mm in diameter and about 4 mm in depth) in the sheet surface along the concave shape of the mold. If necessary, the plug may be raised and lowered at an appropriate timing during the injection of compressed air to assist moldability. The PTP packaging base material produced as described above can be combined with a lid material to form a PTP packaging material.

[0075] In addition to the thermoforming, it is also possible to laminate aluminum foil, aluminum vapor deposition film, plastic film (e.g., biaxially oriented polypropylene film, nylon film, ethylene-vinyl alcohol copolymer film, polyvinylidene chloride film), etc., on the front surface, back surface, or both surfaces of the sheet. It is also possible to form a composite sheet by laminating aluminum foil or the above-mentioned various films, etc., on the front surface, back surface, or both surfaces of the sheet, and then thermoform the composite sheet.

[0076] In addition, in order to improve the design and secondary processability of the product, the sheet surface may be embossed or matte-finished. In this case, a mirror-like sheet may be prepared and then processed with an embossing roll or matte-finish roll, or the cast roll may be changed to an embossing roll or matte-finish roll during extrusion molding. As long as the purpose of the present invention is not impaired, the sheet surface may be coated with an antistatic agent, silicone, wax, etc., a film may be formed using a surface protection sheet for the purpose of preventing scratches, or a printed layer may be provided. Note that any currently known means may be used as the means for forming the printed layer.

[0077] Since the polyolefin-based sheet of the present invention has excellent transparency, moisture resistance, and impact resistance, it can be used in PTP packaging for packaging solid agents such as capsules and tablets, granular foods, etc. in the pharmaceutical and food packaging field, and blister packages for packaging foods, etc. in the food packaging field. EXAMPLES

[0078] The following examples are given, but the present invention is not limited by them. Various measurements and evaluations of the raw materials and polyolefin-based sheets were performed as follows. The flow direction of the polyolefin-based sheet from the extruder is called the machine direction, and the perpendicular direction is called the cross direction.

[0079] [Peel strength] Each test piece formed under the conditions of the examples and comparative examples was cut into a 15 mm wide strip to prepare a T-shaped test piece. The 180° peel strength of each test piece was measured at a speed of 50 mm / min according to the JIS K6854-3 method. [Evaluation Criteria] ○: Peel strength is 5.0N / 15mm or more △: Peel strength is 3.5N / 15mm or more and less than 5.0N / 15mm ×: Peel strength is less than 3.5N / 15mm

[0080] [Moisture resistance (water vapor transmission rate)] According to the JIS K7129-2 method, the water vapor transmission rate of the polyolefin-based sheet was measured in an atmosphere of 40° C. and 90% RH using a PERMATRAN W 3 / 31 (manufactured by MOCON), and evaluated according to the following criteria. [Evaluation Criteria] ◎: Water vapor permeability is 0.53g / (m 2 ·24 hours) or less 〇: Water vapor permeability is 0.53g / (m 2 24 hours) over 0.6g / (m 2 ·24 hours) or less ×: Water vapor permeability is 0.6g / (m 2 - More than 24 hours

[0081] [Transparency (haze)] The total light transmittance and diffuse transmittance of the polyolefin-based sheet were measured using a haze meter according to JIS K7136. The haze was calculated from the total light transmittance and diffuse transmittance obtained using the following formula and evaluated according to the following criteria. [Haze](%)=[Diffuse transmittance] / [Total light transmittance]×100 [Evaluation Criteria] ○: Haze is 40% or less △: Haze is over 40% and 50% or less ×: Haze exceeds 50%

[0082] [Impact resistance] The embrittlement temperature of the film was measured according to the conditions and methods of ASTM D1790 and evaluated according to the following evaluation criteria. [Evaluation Criteria] ◎: Film embrittlement temperature is less than -25°C 〇: Film embrittlement temperature is -25°C or higher and less than 0°C △: Film embrittlement temperature is 0°C or higher and less than 20°C ×: Film embrittlement temperature is 20°C or higher

[0083] <Evaluation of PTP Sheet> A polyolefin-based sheet was used to form a bottom sheet for PTP packaging using a PTP forming device (manufactured by CKD, FBP-300E). Without filling the contents, it was heat-sealed at 250°C using a 20-μm-thick aluminum foil. Further, after making a slit to a depth of 200 μm from the bottom sheet side, it was punched out into a size of approximately 40 mm × approximately 95 mm with a corner R = 5 mm (the 40-mm direction is the longitudinal direction of the sheet) to obtain a PTP molded product as shown in Fig. 1.

[0084] 〔PTP Moldability〕 The temperature of the sheet heating plate in the PTP forming device was changed at 5°C intervals to form the sheet, and the obtained molded body was visually evaluated. The upper and lower limits of the temperature at which a PTP molded product of a level without crushing, deformation, or delamination between layers in the pocket top surface or corner parts for storing tablets and without practical problems can be obtained were determined, and such a temperature range was defined as the temperature range that can be appropriately formed by molding, and the evaluation was carried out according to the following evaluation criteria. [Evaluation Criteria] 〇: The temperature range of the upper and lower limits is 20°C or higher △: The temperature range of the upper and lower limits is 10°C or higher and less than 20°C ×: The temperature range of the upper and lower limits is less than 10°C, or when the pocket shape cannot be formed

[0085] 〔PTP Drop Cracking Property〕 Ten molded PTP molded products were bundled into a set, and a 100g weight was dropped once on each of the four corners of the bundled sheets from a height of 60cm in an environment of 25°C using a PTP sheet drop impact tester (manufactured by Mize Testing Machines Co., Ltd.) to check for the presence or absence of corner cracks. PTP molded products with chipped or cracked corners were judged to have corner cracks, while those in their original state or with folds or bends were judged to have no corner cracks. The above test was performed for 5 sets (n=200), and the evaluation was performed according to the following evaluation criteria. [Evaluation Criteria] ○: Less than 20% of corners are cracked △: The percentage of cracked corners is between 20% and 50%. ×: The rate of corner cracks is 50% or more.

[0086] [PTP push-through opening] A total of six randomly selected male and female subjects in their 20s to 50s were asked to use a wearable load sensor (HapLog, manufactured by Kato Tech Co., Ltd.) to calculate the weighted average load applied by the thumb of the dominant hand when pushing against the body, and then evaluated according to the following criteria. [Evaluation Criteria] ○: Weighted average value is less than 30N △: Average load is 30N or more and less than 40N ×: Average load is 40N or more

[0087] Prior to the examples, the following raw materials were prepared.

[0088] [Polypropylene resin (a)] (a-1): Random polypropylene (propylene / ethylene = 98 / 2 mass% copolymer, density = 0.900 g / cm 3 , MFR=5.0g / 10min) (a-2): Random polypropylene (propylene / ethylene = 97 / 3 mass% copolymer, density = 0.900 g / cm 3 , MFR=1.9g / 10min)

[0089] [Polyethylene resin (b)] (b-1): High-density polyethylene resin (density = 0.952 g / cm 3 , MFR=2.0g / 10min)

[0090] [Thermoplastic resin (c)] (c-1): Hydrogenated derivative of C9 petroleum resin (density = 0.999 g / cm 3 , softening point=125℃)

[0091] <Example 1> For layer (A), (a-1), (a-2), and (c-1) were dry-blended in a mixing mass ratio of 80:10:10, and then kneaded at 230°C using a 40 mmφ single-screw extruder. For layer (B), (b-1) and (c-1) were dry-blended in a mixing mass ratio of 90:10, and then kneaded at 230°C using a 32 mmφ single-screw extruder. Layer (A) and layer (B) were extruded from a T-die so that the lamination ratio was A:B:A = 1:4:1, and then quenched with a casting roll at about 45°C to produce a sheet with a thickness of 300 μm. The obtained sheet was evaluated for interlaminar strength, moisture resistance, transparency, impact resistance, PTP moldability, PTP drop crack resistance, and PTP push-through openability. The results are shown in Table 1 below.

[0092] <Examples 2 and 3, Comparative Examples 1 and 2> A sheet having a thickness of 300 μm was produced and evaluated in the same manner as in Example 1, except that the raw materials for Layer (A) and Layer (B) were mixed in the prescribed ratios shown in Table 1 below. The results are shown in Table 1 below.

[0093] <Reference example> As a reference example, a commercially available polypropylene resin sheet with a thickness of 300 μm was prepared, which is composed of a single layer of homopolypropylene, which is conventionally used as a base material for PTP packaging. The above sheet was similarly evaluated for moisture resistance, transparency, impact resistance, PTP formability, PTP drop crack resistance, and PTP push-through opening properties. The results are shown in Table 1 below.

[0094] [Table 1]

[0095] From the results in Table 1 above, the polyolefin-based sheet of the example having a layer (A) containing a polypropylene-based resin (a) as a main component and a layer (B) adjacent to layer (A) containing a polyethylene-based resin (b) as a main component, in which layer (A) and layer (B) contain a thermoplastic resin (c), and having a specific interlayer strength, was also excellent in moisture resistance, transparency, and impact resistance.

[0096] On the other hand, the polyolefin-based sheets of Comparative Examples 1 and 2 in which the interlaminar strength between the layer (A) and the layer (B) was low were inferior in moisture resistance and transparency and were not suitable for practical use.

[0097] The present invention has been described above in relation to the embodiment that is considered to be the most practical and preferable at present. However, the present invention is not limited to the embodiment disclosed in the specification of this application, and can be modified as appropriate within the scope of the claims and the gist or concept of the invention that can be read from the specification as a whole, and films with such modifications should also be understood to be included within the technical scope of the present invention. [Industrial Applicability]

[0098] The polyolefin sheet of the present invention has excellent moisture resistance, transparency and impact resistance and can therefore be suitably used for various packaging applications, and can be particularly suitably used as a base material for PTP packaging.

Claims

1. A press-through package base material using a polyolefin-based sheet having at least two layers, namely, a layer (A) containing a polypropylene-based resin (a) as a main component and a layer (B) adjacent to the layer (A) containing a polyethylene-based resin (b) as a main component, at least one of the layers (A) and (B) contains at least one thermoplastic resin (c) selected from the group consisting of petroleum resins, terpene resins, chroman-indene resins, rosin-based resins, and hydrogenated derivatives thereof, and the interlaminar strength between the layers (A) and (B) measured in accordance with JIS K6854-3 is 3.5 N / 15 mm or more; the thickness ratio of the layer (A) to the layer (B) is 1:1.8 to 1:3; The press-through package base material, wherein the polyethylene resin (b) is a bio-polyethylene resin.

2. 2. The press-through package base material according to claim 1, wherein a content of the thermoplastic resin (c) contained in at least one of the resin compositions forming the layer (A) and the layer (B) is 7% by mass or more and 40% by mass or less, when the resin compositions forming the layer (A) and the layer (B) are taken as 100% by mass.

3. 3. The press-through package base material according to claim 1, wherein the polypropylene-based resin (a) is at least one of a monocomponent polypropylene and a propylene-ethylene copolymer.

4. The polyethylene resin (b) has a density of 0.935 g / cm3 as measured according to JIS K7112. 3 The press-through package base material according to any one of claims 1 to 3, which is a polyethylene-based resin having the above properties.

5. The water vapor transmission rate measured at a temperature of 40°C and a relative humidity of 90% according to JIS K7129-2 is 0.6 g / (m 2 The press-through package packaging base material according to any one of claims 1 to 4, wherein the shelf life is 24 hours or less.

6. A press-through package packaging material comprising a press-through package base material according to any one of claims 1 to 5 and a lid material.

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