JP2012172100A - Polyethylene-based sheet, lid material for ptp packaging prepared by molding the same, and ptp packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new polyethylene-based sheet having all sufficient press-through properties, moisture resistance, and shock resistance so that it can be preferably used as, e.g., a PTP packaging material.SOLUTION: There is provided the polyethylene-based sheet that is a sheet of which the crystalline melting temperature measured at a heating rate of 10°C/min in differential scanning calorimetry is 100 to 140°C and the crystalline melting heat quantity is 140 to 200 J/g and which contains an ethylene polymer (A), a crystal nucleating agent (B), and a cyclic olefin-based resin (C), wherein the percentage of (B) to the mixture of (A), (B), and (C) is 0.01 mass% or more and 3.0 mass% or less; and the percentage of (C) is 5 mass% or more and 50 mass% or less.

Description

  The present invention relates to a polyethylene-based sheet excellent in press-through property, moisture-proof property, and impact resistance, a PTP packaging lid formed by molding the sheet, and a PTP packaging material.

  In the field of packaging pharmaceuticals and foods, PTP (press-through packaging) packaging is widely used for packaging solid agents such as capsules and tablets, and granular foods. In the field of packaging foods and the like, blister packages that are very similar to PTP packaging are also widely used for packaging foods and the like.

  PTP packaging is, for example, forming a pocket portion for storing a solid agent such as a tablet or capsule by performing pressure forming, vacuum forming or the like using a transparent sheet as a bottom material, and after storing a capsule or the like in the pocket portion, For example, it is a package in a form in which a foil or film of a material that can be easily torn by hand or easily opened like aluminum foil is laminated and integrated as a lid. According to PTP packaging, the solid agent or food stored in the pocket of the bottom material can be directly confirmed with the naked eye before opening, and when opening, push the solid agent etc. in the pocket with your finger to break the lid material Thus, the contents can be easily taken out.

  The blister package is formed by forming a pocket according to the form of food by vacuum forming the sheet, etc., and storing contents such as food in the pocket, and then using heat-sealed coated paper or film. It is a packaging in the form of sealing.

  PTP packaging and blister package lid materials are generally required to have “press-through” and moisture-proof properties that can easily break the lid by pushing the contents of the pockets with your fingers. Aluminum foil is used. However, when aluminum foil is used, it is difficult to inspect foreign objects using a metal detector, the aluminum pieces may be accidentally swallowed when the contents are taken out, and the bottom material and lid at the time of disposal. Since there are problems when aluminum foil is used in various situations such as difficulty in material separation and material recycling, lid materials that do not use aluminum foil are desired.

Therefore, as a cover material that does not use aluminum foil, for example, Patent Document 1 discloses that one side of a biaxial or uniaxially stretched film made of polypropylene or a copolymer thereof, or polypropylene or a copolymer thereof added with a photodegradation accelerator. PTP packaging lid materials provided with a heat seal layer are disclosed.
Patent Document 2 discloses a PTP package in which a high-melting crystalline polyester resin is laminated on one side of a layer made of a mixture of a crystalline polyester resin and a specific block copolymer polyester resin, and at least uniaxially stretched. A lid is disclosed.

On the other hand, Patent Document 3 discloses a lid for PTP packaging made of a polypropylene sheet filled with an inorganic powder.
Patent Document 4 discloses a PTP packaging lid material obtained by blending an inorganic filler with a resin made of polypropylene, polyethylene, ethylene / propylene rubber, or a copolymer or a mixture thereof.
Patent Document 5 discloses a lid for PTP packaging containing a plate-like filler having an average aspect ratio of 10 or more and an average major axis of 0.1 to 20 μm with respect to polypropylene.
In addition, Patent Document 6 discloses a lid for PTP packaging made of a stretched film having at least one layer containing an inorganic filler with respect to a thermoplastic resin.

  Further, in Patent Document 7, a film obtained by adding a petroleum resin to an amorphous polyolefin resin, a film obtained by adding a petroleum resin to an amorphous polyolefin resin, an inorganic material, or a petroleum resin added to an amorphous polyolefin resin, A lid for PTP packaging is disclosed in which a seal layer is laminated on a film to which an organic resin is added.

Japanese Patent Laid-Open No. 06-122180 JP 2004-099137 A JP 09-057920 A JP 09-240727 A JP 2006-052292 A JP 2010-264987 A JP-A-11-313870

  Regarding the techniques of Patent Document 1 and Patent Document 2, since polypropylene or polyester-based resin is used as a base material, it is difficult to obtain sufficient moisture resistance for protecting the contents even if stretching is performed.

  Regarding the techniques of Patent Documents 3 to 5, although the drug take-out property can be improved by adding an inorganic filler, in order to give practically sufficient drug take-out property, the inorganic filler needs to be highly filled and transported. There is concern about the occurrence of damage to the lid material. Moreover, since an inorganic filler is generally hydrophilic, the moisture-proof property of a lid | cover material may be reduced.

Regarding the technique of Patent Document 6, although mechanical characteristics and moisture resistance are improved by stretching, it is very difficult to balance the press-through property and moisture resistance.
Further, regarding the technology of Patent Document 6, it is a cover made of a mixture of an amorphous polyolefin and a petroleum resin, and the contents are obtained by adding a large amount of petroleum resin to the amorphous polyolefin having low impact resistance. On the other hand, there is a concern about the damage of the lid material and contents during transportation.

  Accordingly, in view of the problems of the prior art, an object of the present invention is to provide a new polyethylene sheet having sufficient press-through property, moisture resistance, and impact resistance, and a PTP packaging lid formed by molding the same. It is in providing a material and a PTP packaging material.

The present invention is a sheet comprising the following (A), (B), and (C), and the ratio of (B) in the mixture of (A), (B), and (C) is The present invention proposes a polyethylene sheet characterized by being 0.01% by mass or more and 3.0% by mass or less, and the ratio of (C) being 5% by mass or more and 50% by mass or less.
(A) An ethylene polymer having a crystal melting temperature of 100 to 140 ° C. and a crystal melting heat of 140 to 200 J / g measured at a heating rate of 10 ° C./min in differential scanning calorimetry (B) Crystal Nucleating agent (C) Cyclic olefin resin

  Since the polyethylene sheet proposed by the present invention has sufficient press-through properties, moisture-proof properties, and impact resistance, for example, lids for packaging materials such as pharmaceuticals and foods, particularly PTPs (press-through packs) for pharmaceuticals. Like materials, it can be suitably used as a material that requires press-through properties, moisture resistance, and impact resistance.

It is a schematic sectional drawing which shows an example of a PTP package.

  Hereinafter, a polyethylene-based sheet (hereinafter also referred to as “present sheet”) as an example of an embodiment of the present invention will be described. However, the scope of the present invention is not limited to the embodiments described below.

<Ethylene polymer (A)>
The ethylene-based polymer (A) used in the present sheet may be an ethylene homopolymer, or may be a copolymer of ethylene and a monomer component other than ethylene, particularly an α-olefin. . A mixture of these can also be used.

Here, as the α-olefin copolymerized with ethylene, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, 3-methyl- Examples include butene-1, 4-methyl-pentene-1. Among these, propylene, butene-1, hexene-1, and octene-1 are preferable from the viewpoints of industrial availability, various characteristics, and economical efficiency.
The α-olefin copolymerized with ethylene may be used alone or in combination of two or more.

  Among these, it is preferable to use an ethylene homopolymer or a copolymer of ethylene and at least one α-olefin selected from the group consisting of butene-1, hexene-1, and octene-1.

  When a copolymer of ethylene and at least one α-olefin selected from the group consisting of butene-1, hexene-1 and octene-1 is used, butene-1 and hexene-1 occupy in the copolymer , And the total proportion of octene-1 is preferably 0.1 to 4.0% by mass, particularly 0.3% by mass or more or 3.5% by mass or less, and more preferably 0.5% by mass or more or 3%. More preferably, it is 0.0 mass% or less. If the proportion of the α-olefin is within such a range, the moisture resistance and transparency of the sheet can be further improved.

In addition, as the ethylene polymer (A), it is particularly preferable to use an ethylene homopolymer and / or an ethylene-α-olefin random copolymer that is polymerized using a single site catalyst.
An ethylene homopolymer and / or an ethylene-α-olefin random copolymer polymerized using a single site catalyst has a small molecular weight distribution index (Mw / Mn) and a relatively uniform molecular length. Therefore, when a crystal nucleating agent is added, it becomes possible to form fine crystals, so that transparency and moisture resistance can be particularly improved. From such points, the molecular weight distribution index (Mw / Mn) of the ethylene-based polymer (A) is 2.50 to 5.00, particularly 2.60 or more or 4.50 or less, especially 3.00 or more or 4. It is preferably 00 or less.

  As a single site catalyst, the metallocene catalyst which combined the metallocene compound and methylaluminoxane can be mentioned, for example. Features of ethylene homopolymers and / or ethylene-α-olefin random copolymers polymerized using a single site catalyst include narrow molecular weight distribution and low heat of crystal fusion even at the same density Can be mentioned.

From the viewpoint of moisture resistance, the density of the ethylene polymer (A) is preferably a 0.930~0.958g / cm ^3, among them 0.932 g / cm ³ or more, or 0.947 g / cm ³ by more preferably less, and more preferably 0.935 g / cm ³ or more, or 0.942 g / cm ³ or less therein. If the density of the ethylene polymer (A) is within such a range, the moisture resistance of the sheet can be further improved.

The ethylene polymer (A) has a crystal melting temperature of 100 to 140 ° C. measured at a heating rate of 10 ° C./min in differential scanning calorimetry and a crystal melting heat of 140 to 200 J / g. is required. By using the ethylene polymer (A) having a crystal melting temperature and a crystal melting heat amount within such a range, it is possible to exhibit excellent moisture resistance as a lid material for PTP packaging or blister package. Among these, the crystal melting temperature is more preferably 110 ° C. or higher, and further preferably 120 ° C. or higher.
The heat of crystal fusion is more preferably 145 J / g or more, and more preferably 150 J / g or more.
The upper limit of the heat of crystal fusion is 200 J / g.
Such a crystal melting temperature can be measured using a differential scanning calorimeter at a heating rate of 10 ° C./min according to JIS K7121, and the crystal melting calorie can be measured using a differential scanning calorimeter. According to the above, it can be measured at a heating rate of 10 ° C./min.

<Crystal nucleating agent (B)>
The kind of the crystal nucleating agent (B) used in the sheet is not particularly limited as long as the effect of improving the moisture resistance of the ethylene polymer (A) is recognized.
For example, dibenzylidene sorbitol (DBS) compounds, 1,3-O-bis (3,4 dimethyl benzylidene) sorbitol, dialkyl benzylidene sorbitol, diacetals of sorbitol having at least one chlorine or bromine substituent, di (methyl or ethyl substituted benzylidene) ) Sorbitol, bis (3,4-dialkylbenzylidene) sorbitol with substituents forming carbocycles, aliphatic, alicyclic and aromatic carboxylic acids, dicarboxylic acids or polybasic polycarboxylic acids, corresponding anhydrides Metal salts of organic acids such as organic and metal salts, bicyclic dicarboxylic acids and salts such as cyclic bis-phenol phosphate, disodium bicyclo [2.2.1] heptene dicarboxylic acid, bicyclo [2.2 .1] Heptane-dicarboxylate Bicyclic dicarboxylate saturated metal or organic salt compounds such as 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-ethylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (m-isopropylbenzylidene)- D-sorbitol, 1,3: 2,4-bis-O- (mn-propylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (mn-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- (pn-propylbenzylidene) -D-sorbitol, 1,3: 2,4-bis-O- (p- n-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-sorbite 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, -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] − -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- Chlorbenzylidene-D-sorbitol, 1,3-O-p-chlorobenzylidene-2,4-O-benzylidene-D-sorbitol, 1,3-O-benzylidene-2,4-O- (2,4-dimethyl Benzylidene) -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-O-p-ethylbenzylidenesorbitol, 1,3-p-ethyl-benzylidene-2,4-p-methylbenzylidene-D-sorbitol, 1,3-Op-methyl-benzylidene-2,4 Dia such as -Op-chlorobenzylidene-D-sorbitol, 1,3-Op-chloro-benzylidene-2,4-Op-methylbenzylidene-D-sorbitol Tar compounds, 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, tridecanoic acid, myristic acid Acids, fatty acids such as pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, montanic acid, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, hebenic acid amide, stearin Magnesium oxide, zinc stearate, calcium stearate Fatty acid metal salts such beam, silica, talc, kaolin, inorganic particles such as calcium carbonate, glycerol, can be mentioned higher fatty acid esters such as glycerin monoesters, and the like.
Among these, fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, and hebeninic acid amide, and fatty acid metal salts such as magnesium stearate, zinc stearate, and calcium stearate are particularly preferable.
One of these crystal nucleating agents can be used alone, or two of these can be selected and used in combination.

  As specific examples of the crystal nucleating agent (B), the product name “Gelall D” series of Shin Nippon Rika Co., Ltd., the product name “Adekastab” of Asahi Denka Kogyo Co., Ltd. ”,“ Hyperform ”, trade name“ IRGACLEAR ”of BASF Corp., etc. In addition, as a master batch of crystal nucleating agent, trade name“ Rike Master CN ”of Riken Vitamin Co., Ltd. Product name “Hyperform Concentrate” and the like. Among these, products that have a particularly high effect of improving moisture resistance include “Hyperform HPN-20E” and “Hyperform Concentrate HL3-4” from Milliken Chemical Co., Ltd., and “Rike Master CN-” from Riken Vitamin Co., Ltd. 001 "," Rike Master CN-002 ".

<Cyclic olefin resin (C)>
It is important that the sheet contains a cyclic olefin resin (C) that is incompatible with the ethylene resin (A). By containing such a cyclic olefin-based resin (C), the cyclic olefin-based resin (C) serves as a starting point of breakage at the time of press-through, and therefore has excellent press-through properties without reducing moisture resistance. Can be granted.

As the cyclic olefin-based resin (C), (i) a polymer obtained by hydrogenating a ring-opened (co) polymer of cyclic olefin as necessary, (ii) an addition (co) polymer of cyclic olefin, (iii) cyclic Examples include random copolymers of olefins and α-olefins such as ethylene and propylene, and (iv) graft modified products obtained by modifying the above (i) to (iii) with unsaturated carboxylic acids or their derivatives.
Specifically, the product name “ZEONOR” series of Nippon Zeon Co., Ltd., the product name “Apel” series of Mitsui Chemicals, Inc., and the product name “TOPAS” series of Polyplastics Co., Ltd. can be mentioned. The cyclic olefin polymers are described in, for example, JP-A-60-168708, JP-A-61-115916, JP-A-61-271308, JP-A-61-252407. It can also be produced according to known methods.

  In addition, a cyclic olefin ring-opening (co) polymer or a hydrogenated product of a cyclic olefin ring-opening (co) polymer may be used, such as maleic anhydride, maleic acid, itaconic anhydride, itaconic acid, (meth) acrylic acid, etc. A graft copolymer modified with a modifier of a saturated carboxylic acid or its anhydride can also be used.

  The glass transition temperature of the cyclic olefin resin (C) is preferably 50 to 105 ° C, more preferably 55 to 90 ° C. If the glass transition temperature of the cyclic olefin resin is within such a range, the press-through property can be improved without reducing the heat resistance of the sheet.

  The cyclic olefin resin (C) is preferably amorphous. For example, when ethylene and an alicyclic olefin such as norbornene, dicyclopentadiene, and tetracyclododecene are copolymerized, the crystallinity decreases as the copolymerization ratio of these alicyclic olefins increases. At the same time, since the ethylene ratio is lowered, the compatibility with the ethylene polymer (A) is lowered, and the press-through property is improved.

(Content ratio of each component)
It is important that the content of the crystal nucleating agent (B) in the mixture of (A), (B), and (C) is 0.01 to 3.0% by mass, especially 0.03. More preferably, it is more than mass% or 2.0 mass% or less, and it is especially more preferable that it is 0.05 mass% or more or 1.0 mass% or less among them. By blending the crystal nucleating agent (B) within such a range, moisture resistance can be effectively improved without causing deterioration of heat resistance and mechanical properties due to excessive addition of the crystal nucleating agent.

  Further, it is important that the content of the cyclic olefin resin (C) in the mixture of (A), (B), and (C) is 5% by mass or more and 50% by mass or less, The content is more preferably 10% by mass or more and 45% by mass or less, and particularly preferably 15% by mass or more and 40% by mass or less. By mix | blending cyclic olefin resin (C) within this range, press-through property can be improved effectively, without reducing impact resistance.

<Olefin compatible resin (D)>
The sheet preferably further contains an olefin-compatible resin (D) from the viewpoint of further improving moisture resistance.

  The olefin compatible resin (D) is preferably a resin that is compatible with an olefin resin, particularly an ethylene polymer (A), and has a glass transition temperature higher than that of the ethylene polymer (A). Examples of such resins include petroleum resins, terpene resins, coumarone-indene resins, rosin resins, and one or more resins selected from the group consisting of these hydrogenated derivatives. .

  Examples of the petroleum resin include alicyclic petroleum resin from cyclopentadiene or its dimer, aromatic petroleum resin from C9 component, and the like. Examples of the terpene resin include terpene-phenol resins from β-pinene. Furthermore, examples of the rosin resin include rosin resins such as gum rosin and wood rosin, and esterified rosin resins modified with glycerin, pentaerythritol, and the like.

  Such an olefin-compatible resin (D) exhibits relatively good compatibility when mixed with the ethylene-based polymer (A), and further enhances color tone, thermal stability, compatibility, moisture resistance, and the like. From the above, the hydrogenated derivative, particularly the hydrogenation rate (hereinafter referred to as “hydrogenation rate”) is 95% or more, and is substantially free of polar bonds such as hydroxyl groups, carboxyl groups and halogens, or unsaturated bonds such as double bonds. It is preferable to use petroleum resin or terpene resin which is not contained above.

The olefin compatible resin (D) can be obtained in various softening temperatures by changing the molecular weight.
The softening temperature Ts (D) measured based on JIS K2207 of the olefin compatible resin (D) is the crystallization peak temperature measured at a cooling rate of 10 ° C./min in the differential scanning calorimetry of the ethylene polymer (A). Tc (A) + 15 ° C. or lower, that is, it is preferable not to reach a high temperature exceeding the crystallization peak temperature Tc (A) + 15 ° C., more preferably Tc (A) + 10 ° C. or lower, Tc (A) + 5 ° C. or lower More preferably. The lower limit of Tc (A) is 80 ° C.

  When the upper limit of the softening temperature Ts (D) of the olefin compatible resin (D) satisfies the above condition, the degree of freedom of the olefin compatible resin (D) molecule is high in the crystallization process of the ethylene polymer (A). In this state, crystallization of the ethylene polymer (A) is not inhibited, fine crystals are formed, and a polyethylene sheet excellent in moisture resistance can be obtained. Moreover, if Ts (D) is 80 ° C. or higher, pellet blocking during molding and bleeding out to the surface of the molded product during secondary processing, transportation, or use will not occur.

  Specific examples of the olefin-compatible resin (D) include, for example, Mitsui Chemicals, Inc., trade names “Hilets” series, “Petrogin” series, Arakawa Chemical Industries, Ltd., trade names “Arcon” series, Yasuhara Chemical ) Product name “Clearon” series, Idemitsu Petrochemical Co., Ltd. product name “Imabe” series, Tonex Co., Ltd. product name “Escollet” series.

  The content of the olefin-compatible resin (D) is such that the proportion of the mixture of (A), (B), (C), and (D) is 5% by mass or more and 30% by mass or less. Among them, the content is more preferably 10% by mass or more and 25% by mass or less, and particularly preferably 15% by mass or more and 20% by mass or less. By blending the olefin-compatible resin (D) within such a range, moisture resistance can be further improved without reducing the bleeding of the olefin-compatible resin to the sheet surface and the impact resistance of the sheet.

  In addition, within the range that does not impair the effects of the present invention, for the resin composition constituting the sheet, a polyolefin resin other than the ethylene polymer (A), a polystyrene resin, a polyester resin, a polyolefin resin, or Contains resins such as polystyrene-based thermoplastic elastomers, and additives such as heat stabilizers, antioxidants, UV absorbers, light stabilizers, antibacterial and antifungal agents, antistatic agents, lubricants, pigments, dyes, etc. Can be made.

<Method for producing this sheet>
The manufacturing method of this sheet | seat is not specifically limited. For example, the ethylene polymer (A), the crystal nucleating agent (B), the cyclic olefin resin (C), and other additives are melt-mixed with a single screw or twin screw extruder, etc. An unstretched sheet can be produced by extrusion, quenching with a cast roll, and solidifying.

The molding temperature is appropriately adjusted because the flow characteristics vary depending on the type and mixing ratio of the resin, the presence and type of the additive, and is generally 180 to 260 ° C, preferably 200 to 240 ° C.
Here, the unstretched sheet means a sheet that is not actively stretched for the purpose of increasing the strength of the sheet. For example, a sheet that has been stretched to less than 2 times by a stretching roll during extrusion molding is included in the unstretched sheet. Shall be.

When the multilayer sheet is formed by laminating other layers within a range that does not impair the effect of the sheet, the multilayering method is a known method such as coextrusion, extrusion lamination, thermal lamination, dry lamination, etc. Can be used.
In particular, in the case of coextrusion, each material constituting each layer is melt-mixed with separate extruders, laminated and extruded using a feed block, a multi-manifold die, etc., and rapidly cooled and solidified with a cast roll. Can be produced.
In the case of thermal lamination, the non-stretched sheets constituting each layer can be produced separately and then overlapped, followed by pressure lamination through a heat laminating roll.

  Furthermore, the roll method, tenter method, tubular method, etc. are used uniaxially or biaxially for the purpose of further improving heat resistance, moisture proofing, and impact resistance within a range that does not impair the secondary workability of this sheet. It can also be stretched.

<Sheet thickness>
The thickness of the sheet is not particularly limited. For example, when considering the press-through property and impact resistance, it is preferably 0.02 mm or more and 0.2 mm or less, more preferably 0.03 mm or more and 0.18 mm or less, 0.05 mm or more, 0 More preferably, it is 15 mm or less. If the thickness of this sheet is 0.02 mm or more, excellent impact resistance can be obtained, and damage to the contents can be prevented when used for PTP packaging, blister packaging, and the like. On the other hand, if the thickness of this sheet is 0.2 mm or less, excellent press-through properties can be exhibited, and the contents can be easily taken out when used for PTP packaging, blister packaging, and the like.

  Moreover, when it is set as the multilayer sheet which laminated | stacked the other layer on this sheet | seat, the thickness ratio of each layer can be adjusted suitably in the range which does not impair the effect of this invention. At this time, the lower limit of the ratio of the present sheet in the thickness direction is preferably 50% or more, more preferably 60% or more, and further preferably 70% or more. The upper limit is 100%. By adjusting the thickness ratio of the multilayer sheet within such a range, it is possible to provide a polyethylene sheet excellent in press-through property and moisture-proof property.

<Physical properties of this sheet>
When this sheet is used as a lid for PTP packaging or blister package, water vapor at a thickness of 0.08 mm measured at a temperature of 40 ° C. and a relative humidity of 90% based on JIS K7129B method from the viewpoint of preventing deterioration of the contents due to moisture. The transmittance is preferably 1.5 g / (m ² · 24 hours) or less, more preferably 1.0 g / (m ² · 24 hours) or less, and particularly 0.8 g / (m ² · 24 hours) or less. If the water vapor transmission rate at a thickness of 0.08 mm is 1.5 g / (m ² · 24 hours) or less, a product having sufficient moisture resistance as a packaging material can be obtained.

Furthermore, from the viewpoint of press-through property and impact resistance, the through-hole strength at a thickness of 0.08 mm as measured according to JIS Z1707 for this sheet is preferably 1.5 N or more and 3.0 N or less, particularly 1.7 N As described above, it is more preferably 2.8 N or less, and even more preferably 1.9 N or more and 2.5 N or less.
If this sheet has a through hole strength of 1.5 N or more, the sheet will not be easily broken by an impact from the outside and has excellent impact resistance. Can be protected. Moreover, if the through-hole intensity | strength of this sheet | seat is 3.0 N or less, it can be used as a cover material for PTP packaging excellent in press-through property.

<Use of this sheet>
This sheet can be formed into molded bodies having various shapes by vacuum forming, pressure forming, pressure vacuum forming, press forming, and other thermoforming. For example, it can be suitably used as a lid or bottom material of a packaging molded body, particularly a packaging container such as PTP packaging or blister package.

For example, when PTP packaging is performed using this sheet as a lid, a pocket is formed in the bottom sheet by vacuum or pressure forming, and then the contents are filled in the pocket. The PTP package can be manufactured by pasting the present sheet using a method such as heat fusion or pressure bonding.
Moreover, if this sheet is molded and used as the bottom material of a PTP packaging container, not only can a PTP packaging container excellent in press-through property, moisture resistance, and impact resistance be produced, but also the recyclability of used PTP packaging material. It is suitable because it is excellent.

Further, for the purpose of improving the design property of the product and the fusion property with the bottom material, the surface of the sheet may be subjected to processing such as embossing or matting. In this case, even if a mirror-like sheet is once created and then processed with an embossing roll or a matte roll, the cast roll is changed to an embossing roll or a matte roll during extrusion molding. May be.
As long as the gist of the present invention is not impaired, the surface of the sheet may be coated with an antistatic agent, silicone, wax, etc., a film may be formed using a surface protective sheet for the purpose of preventing fouling adhesion, etc. It is also possible. Note that any currently known means can be adopted as the means for forming the print layer.

  As described above, the sheet is excellent in all of press-through property, moisture resistance, and impact resistance. For example, in the packaging field such as pharmaceuticals and foods, it is used for packaging solid agents such as capsules and tablets, granular foods, and the like. It can be used for lid materials for PTP packaging and blister packages for packaging foods in the packaging field such as foods.

  Examples are shown below, but the present invention is not limited by these. In addition, the various measured value and evaluation about the raw material and sheet | seat (sample) which are displayed in this specification were performed as follows. Here, the flow direction from the extruder of the film is called the vertical direction, and the orthogonal direction is called the horizontal direction.

(1) Crystal melting temperature (Tm)
Using a differential scanning calorimeter of Perkin Elmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 1 ° C. for 1 minute, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./minute, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./minute, the crystal melting temperature (Tm) (° C.) was determined.

(2) Heat of crystal melting (ΔHm)
Using a differential scanning calorimeter of Perkin Elmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7122, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. After holding at 1 ° C. for 1 minute, the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min, and again from the thermogram measured when the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min (ΔHm) (J / g) was determined.

(3) Crystallization peak temperature (Tc)
Using a differential scanning calorimeter of Perkin Elmer Co., Ltd., trade name “Pyris1 DSC”, according to JIS K7121, about 10 mg of the sample was heated from −40 ° C. to 200 ° C. at a heating rate of 10 ° C./min. The crystallization peak temperature Tc (° C.) was obtained from the thermogram measured when the temperature was lowered to −40 ° C. at a cooling rate of 10 ° C./min after holding at 1 ° C. for 1 minute.

(4) Softening temperature (Ts)
The softening temperature of the olefin compatible resin (D) was determined according to JIS K2207.

(5) Molecular weight distribution index (Mw / Mn)
The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured using a trade name GPC system of Nippon Waters Co., Ltd., and the molecular weight distribution index (Mw / Mn) was calculated.

(6) Moisture resistance (water vapor transmission rate)
Based on JIS K7129B, using a product name PERMATRAN W 3/31 of MOCON, water vapor permeability when a sheet (sample) having a thickness of 0.08 mm is left to stand in an atmosphere of 40 ° C. and 90% RH for 24 hours. Was measured.
A water vapor transmission rate of 1.5 g / (m ² · 24 hours) or less was accepted.

(7) Press-through property A polypropylene sheet having a thickness of 0.3 mm (trade name Superfoil E0030NA from Mitsubishi Plastics Co., Ltd.) is used as the bottom material, and this is used as a product name FBP- by CKD as a PTP molding machine. After heating with a hot plate at about 140 ° C. using 200 U, a pocket was formed by pressurizing with pressure. Next, after the contents (tablets) are loaded into the pocket portion, the bottom material and a sheet (sample) as a lid material are heat-welded with a pocket-type roll and a heating roll of about 160 ° C., and PTP packaging is performed. Was molded.

The contents (tablets) were taken out by pushing the pocket portion of the obtained PTP package with a finger, and the press-through property was evaluated according to the following criteria.
○: The contents could be taken out with the same feel as a general aluminum foil lid.
Δ: Although there was some resistance, the contents could be taken out at a level where there was no practical problem.
X: The lid was not torn and the contents could not be taken out.

(8) Penetration strength Based on JIS Z1707, the load when a stylus bar having a diameter of 1 mm and a tip shape radius of 0.5 mm was pierced on a 0.08 mm thick sheet (sample) at a test speed of 50 mm / min was measured.
Those having a through-hole strength of 1.5 N or more and 3.0 N or less were accepted.

<Materials used>
[Ethylene polymer (A)]
(A) -1: an ethylene polymer polymerized with a metallocene catalyst (ethylene / butene-1 / octene-1 = 97.9 / 0.8 / 1.3 mass%, density = 0.947 g / cm ³ , (Crystal melting temperature = 131 ° C., crystal melting heat amount = 181 J / g, crystallization peak temperature Tc (A) = 113 ° C., Mw / Mn = 2.87)
(A) -2: ethylene polymer polymerized with a metallocene catalyst (ethylene / hexene-1 / octene-1 = 96.3 / 2.4 / 1.3 mass%, density = 0.937 g / cm ³ , Crystal melting temperature = 126 ° C., heat of crystal melting = 158 J / g, crystallization peak temperature Tc (A) = 112 ° C., Mw / Mn = 2.87)
(A) -3: ethylene homopolymer (ethylene = 100% by mass, density = 0.958 g / cm 3, crystal melting temperature = 134 ° C., heat of crystal melting = 195 J / g, crystallization peak temperature Tc (A) = 116 ° C, Mw / Mn = 4.72)

[Crystal nucleating agent (B)]
(B) -1: fatty acid metal salt (zinc stearate / 1,2-cyclohexanedicarboxylic acid calcium salt = 34/66 mass%)

[Cyclic olefin resin (C)]
(C) -1: Cyclic olefin resin (trade name “TOPAS9506F-04” manufactured by Polyplastics Co., Ltd., glass transition temperature = 68 ° C., amorphous (heat of crystal melting = 0 J / g))

[Olefin compatible resin (D)]
(D) -1: Hydrogenated petroleum resin (trade name “Arcon P115” manufactured by Arakawa Chemical Industries, Ltd., softening temperature Ts (D) = 115 ° C.)

Example 1
After dry blending (A) -1, (B) -1, and (C) -1 at a mixing mass ratio of 89.9: 0.1: 10, using a 40 mmφ co-directional twin screw extruder. After kneading at 230 ° C., it was extruded from a T-die and then rapidly cooled with a casting roll at about 40 ° C. to produce a sheet (sample) having a thickness of 0.08 mm.
About the obtained sheet | seat (sample), moisture-proof (water vapor permeability), press-through property, and through-hole strength were evaluated. The results are shown in Table 1.

(Example 2)
Production and evaluation of sheets in the same manner as in Example 1 except that the mixing mass ratio of (A) -1, (B) -1 and (C) -1 was 69.9: 0.1: 30. Went. The results are shown in Table 1.

(Example 3)
Production and evaluation of sheet in the same manner as in Example 1 except that the mixing mass ratio of (A) -1, (B) -1 and (C) -1 was 54.9: 0.1: 45. Went. The results are shown in Table 1.

Example 4
Production and evaluation of sheets in the same manner as in Example 1 except that the mixing mass ratio of (A) -1, (B) -1 and (C) -1 was 69.95: 0.05: 30. Went. The results are shown in Table 1.

(Example 5)
A sheet was prepared and evaluated in the same manner as in Example 1 except that the mixing mass ratio of (A) -1, (B) -1, and (C) -1 was 69: 1: 30. The results are shown in Table 1.

(Example 6)
After dry blending (A) -1, (B) -1, (C) -1, and (D) -1 at a mixing mass ratio of 49.9: 0.1: 30: 20, Examples A sheet was prepared and evaluated in the same manner as in No. 1. The results are shown in Table 1.

(Example 7)
After dry blending (A) -2, (B) -1, and (C) -1 at a mixing mass ratio of 69.9: 0.1: 30, the sheet was formed in the same manner as in Example 1. Fabrication and evaluation were performed. The results are shown in Table 1.

(Example 8)
After dry blending (A) -3, (B) -1, and (C) -1 at a mixing mass ratio of 69.9: 0.1: 30, the sheet was formed in the same manner as in Example 1. Fabrication and evaluation were performed. The results are shown in Table 1.

(Comparative Example 1)
Using (A) -1 alone, a sheet was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
After dry blending (A) -1 and (B) -1 at a mixing mass ratio of 99.9: 0.1, a sheet was produced and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
After dry blending (A) -1 and (C) -1 at a mixing mass ratio of 70:30, a sheet was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 4)
After dry blending (A) -1, (B) -1, and (C) -1 at a mixing mass ratio of 39.9: 0.1: 60, the sheet was formed in the same manner as in Example 1. Fabrication and evaluation were performed. The results are shown in Table 1.

(Comparative Example 5)
Trade name Umerit 2040FC (linear low density polyethylene, density = 0.918 g / cm ³ , heat of crystal fusion = 134 J / g, molecular weight distribution index) instead of ethylene polymer (A) = 2.80, hereinafter referred to as (P) -1), and (P) -1, (B) -1, and (C) -1 were mixed at a mass ratio of 69.9: 0.1: 30. After the dry blending at the ratio, a sheet was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 1.

As is clear from Table 1, the sheets prepared in Examples 1 to 8 were excellent in moisture resistance, press-through property, and impact resistance, and were suitable for use as a lid for PTP packaging.
On the other hand, the sheet produced in the comparative example was inferior to the polyethylene sheet of the present invention in at least one of moisture resistance, press-through property, and impact resistance.

From this result and the results of the tests conducted so far, the proportion of (B) in the mixture of (A), (B), and (C) is 0.01 to 3.0% by mass, and If the ratio of (C) is 5 to 50% by mass, the same effects as in Examples 1 to 8 can be obtained.
Moreover, if the ethylene-type polymer (A) is an ethylene polymer whose crystal melting temperature is 100 to 140 ° C. and whose crystal melting heat is 140 to 200 J / g, it was used in Examples 1 to 8. It is thought that the same effect as an ethylene polymer can be acquired.

  With respect to the ethylene polymer (A), at least one selected from the group consisting of butene-1, hexene-1, and octene-1 as a monomer component other than ethylene, from the viewpoint of further improving moisture resistance and transparency. The thing containing the alpha olefin of a kind is preferable, and it is that the sum total of the ratio of butene-1, hexene-1 and octene-1 which occupies in (A) is 0.1-4.0 mass%. It can be considered preferable.

Example 9
A sheet having a thickness of 0.3 mm was prepared in the same material ratio and procedure as in Example 6, and this was used as a bottom material, while the sheet having a thickness of 0.08 mm prepared in Example 6 was used as a lid. A PTP package was prepared as follows.

After heating a sheet having a thickness of 0.3 mm obtained by the same material ratio and procedure as in Example 6 with a hot plate at about 140 ° C. using a product name FBP-200U of CKD Corp. as a PTP molding machine. Compressed air was applied to form a pocket portion to form a bottom material. Next, after the contents (tablets) were loaded into the pocket portion, the bottom material and the 0.08 mm-thick sheet (lid material) produced in Example 6 were formed by a pocket-type roll and a heating roll of about 160 ° C. Were heat-welded to prepare a PTP package.
The PTP package obtained in this way has not only excellent press-through properties, moisture resistance and impact resistance, but also excellent recyclability because the lid material and the bottom material have the same composition. It was.

Claims (7)

It comprises the following (A), (B), and (C), and the proportion of (B) in the mixture of (A), (B), and (C) is 0.01% by mass or more, A polyethylene sheet, characterized in that it is 3.0% by mass or less and the ratio of (C) is 5% by mass or more and 50% by mass or less.
(A) An ethylene polymer having a crystal melting temperature of 100 to 140 ° C. and a crystal melting heat of 140 to 200 J / g measured at a heating rate of 10 ° C./min in differential scanning calorimetry (B) Crystal Nucleating agent (C) Cyclic olefin resin   The (A) contains at least one α-olefin selected from the group consisting of butene-1, hexene-1 and octene-1 as a monomer component other than ethylene, and in the (A) 2. The polyethylene sheet according to claim 1, wherein the total of the proportions of butene-1, hexene-1 and octene-1 in the water is 0.1 to 4.0% by mass. The water vapor transmission rate at a thickness of 0.08 mm measured at a temperature of 40 ° C. and a relative humidity of 90% based on JIS K7129B method is 1.5 g / (m ² · 24 hours) or less. 2. The polyethylene sheet according to 2.   The polyethylene sheet according to any one of claims 1 to 3, wherein the through hole strength at a thickness of 0.08 mm measured according to JIS Z1707 is 1.5 N or more and 3.0 N or less.   The lid | cover material for PTP packaging which consists of a polyethylene-type sheet | seat in any one of Claims 1-4.   The PTP packaging material formed by combining the cover material for PTP packaging which consists of a polyethylene-type sheet | seat in any one of Claims 1-4, and the bottom material for PTP packaging.   A PTP formed by combining the PTP packaging lid material made of the polyethylene sheet according to any one of claims 1 to 4 and the PTP packaging bottom material made of the polyethylene sheet according to any one of claims 1 to 4. Packaging material.

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