JP2019172780A - Polypropylene-based sealant film and laminate using the same - Google Patents

Abstract

To provide a polypropylene-based sealant film having excellent easy-tearing property in a film longitudinal direction, excellent in heat sealability and low temperature impact resistance, and excellent in blocking resistance and orange peel surface resistance, and provide a laminate using the same.SOLUTION: There is provided a polypropylene-based sealant film consisting of a resin composition containing 35 to 45 wt.% of a propylene ethylene block copolymer (a) having percentage of 20°C xylene insoluble part of 75 to 85 wt.%, intrinsic viscosity of the insoluble part of 1.7 to 2.0 dl/g, intrinsic viscosity of a soluble part of 3.0 to 3.4 dl/g, 40 to 55 wt.% of a propylene ethylene block copolymer (b) having 20°C xylene insoluble part of 85 to 95 wt.%, intrinsic viscosity of the insoluble part of 1.5 to 2.0 dl/g, intrinsic viscosity of the soluble part of 1.4 to 2.0 dl/g, 5 to 20 wt.% of low density polyethylene polymer (c), and metal phosphate of 1500 to 10000 ppm as a crystal nucleus.SELECTED DRAWING: None

Description

  The present invention relates to a polypropylene-based sealant film used as a sealant for a packaging bag and a laminate using the same.

Conventionally, an unstretched film (hereinafter referred to as CPP) mainly composed of a propylene / ethylene block copolymer has been used as a sealant film for high retort packaging that is sterilized by retort at a high temperature of 120 ° C. to 135 ° C. . The main method of use is to laminate with a laminated base material layer such as a stretched polyethylene terephthalate film (hereinafter referred to as PET), a stretched nylon film (hereinafter referred to as ON), an aluminum foil (hereinafter referred to as Al foil), PET / ON / The laminate is made of Al foil / CPP, PET / Al foil / ON / CPP, or PET / Al foil / CPP, and then used as a bag.

  However, when an unstretched film formed by melt extrusion of a resin blended with propylene / ethylene block copolymer or ethylene-based elastomer in propylene / ethylene block copolymer of Patent Documents 1 and 2 is used for a retort pouch, At the time of opening from the notch portion (cut provided at the end portion), the straight cut property is poor, and the contents are deformed or spilled.

  Therefore, a sealant film used for a retort pouch is required to be easily tearable from a notch portion without using a blade (easy tearability).

  As a polypropylene film having easy tearability, there is a uniaxially stretched film (Patent Document 3) formed by stretching at a high magnification in the longitudinal direction. The film of Patent Document 3 is improved in tearing property but is resistant to low temperatures. Impact properties were insufficient for retort applications. In addition, for the purpose of increasing the crystallinity of the film and imparting tearability, there are films formed by blending sorbitol derivatives (Patent Document 4) and films formed by blending rosin metal salt compounds (Patent Document 5). , Many odors and extracts after retort treatment are not suitable for high retort applications. Furthermore, there are films formed by blending crystalline polyethylene resins (Patent Document 6) and films formed by blending polybutene-1 as a crystal nucleating agent (Patent Document 7), both of which are inferior in low-temperature impact resistance. Therefore, it was insufficient as a high retort application.

  As described above, the conventional technology has easy tearability in the resin extrusion direction (hereinafter referred to as the flow direction (MD)), and also has low-temperature impact resistance, heat sealability, and blocking resistance. There was no polypropylene-type unstretched film that could be widely used for high retort applications (sterilized at 125 to 135 ° C).

  Further, physical properties such as low-temperature impact resistance, heat sealability, and blocking resistance have been required for the CPP constituting the innermost surface.

  In recent years, the size of pouches for business use has increased, and the required level of low temperature impact resistance has become higher. In addition, the required level of pouch appearance is also increasing, and it is desired to minimize the occurrence of fine uneven appearance on the surface of the laminate, that is, so-called crushed skin, after retort sterilization.

  In addition, since the slipperiness between the CPP of the laminate and the laminate base material layer is poor, the CPP of the laminate and the laminate base material layer stick in the film forming process, the slitting process, the bag making process, the content filling process, and the like. When the so-called blocking phenomenon occurs and the film is stored for a long period of time or at a high temperature, when the laminated film is used, it becomes difficult to unwind the film, and the bag-making workability and the filling workability are remarkably lowered.

  In order to solve the above-mentioned problems, a blocking inhibitor, for example, a method of preventing blocking by applying a powder such as starch subjected to a water resistant surface treatment to a sealant, a method of avoiding blocking by a so-called powdering method has been adopted. However, the powdering method is a factor that reduces the value of the product, such as the appearance of the bag making being impaired, the powder being mixed into food filled with food, and adversely affecting the taste, so there is no need for powdering. Therefore, development of a polypropylene film that can be used as a so-called non-powder and can also be suitably used for a high retort application as a packaging bag or a sealant for a packaging bag has been strongly desired.

  Further, as another method for solving the above-mentioned problem, for example, in Patent Document 8, a base film, a sealant layer formed on one surface of the base film, and formed on the other surface of the base film The laminated body characterized by containing the anti-blocking modified layer made was disclosed. Resin composition containing at least one copolymer selected from the group consisting of a graft copolymer of polyester and an acrylic polymer and a graft copolymer of polyurethane and an acrylic polymer as the anti-blocking modified layer Proposals have been made, but applying a lubricant directly to the surface of the anti-blocking layer not only makes the process complicated, but also improves the slipperiness required to the bag making process, filling process, etc. It was not enough for that.

  Further, in Patent Document 9, a laminated film in which a base material layer and a sealant layer are laminated, and the base material layer is formed by multilayer coextrusion film formation, and the outermost layer of the multilayer coextrusion film formation is formed. Proposals have been made as a laminate having an easy-slip layer containing a lubricant and / or an anti-blocking agent, and a packaging container using the same, but since it contains an organic lubricant, a sealant extrusion process, a slit process In the bag making process, the content filling process, etc., the lubricant is transferred to the roll, so that the productivity is deteriorated.

In Patent Document 10, (1) a density of 0.930 g / cm ³ or more, a Vicat softening point of 105 to 125 ° C., and a melt flow rate of 2 to 25 g / 10 min. A polyethylene composition comprising 40% by weight to 90% by weight of density polyethylene and (2) 10% by weight to 60% by weight of linear low density polyethylene by metallocene catalyst or single site catalyst having a density of 0.929 g / cm ³ or less. When forming a laminate layer on the substrate by extrusion coating, the surface roughness Rz is adjusted to 5 to 12 μm and the hole diameter is reduced and the number of holes is reduced and processed without dusting. Proposal has been made as possible, but for high retort applications (125 ° C to 135 ° C sterilization), the mainstream of retort It could not be supported.

JP 2003-105164 A JP 2000-186159 A JP 7-138423 A Japanese Patent Laid-Open No. 1-299831 JP-A-11-255910 Japanese Patent Laid-Open No. 10-316772 Japanese Patent No. 3813263 JP-A-10-76607 JP 2004-284126 A JP 2004-338147 A

  The object of the present invention is to use as non-powder as a sealant for packaging bags with excellent tearability in the flow direction (MD) of resin, excellent heat sealability and low temperature impact resistance, and excellent blocking resistance. It is possible to provide a polypropylene-based sealant film that can be suitably used for high retort applications due to its excellent resistance to scratch skin and a laminate using the same.

  As a result of various studies, the present inventors have solved the above problem.

That is, according to the present invention, the proportion of the 20 ° C. xylene insoluble part is 75 to 85% by weight, the intrinsic viscosity ([η] _H ) of the insoluble part is 1.7 to 2.0 dl / g, and the intrinsic viscosity of the soluble part. ([Η] _EP ) is 3.0 to 3.4 dl / g of propylene / ethylene block copolymer (a) 35 to 45% by weight, 20 ° C. xylene insoluble part ratio is 85 to 95% by weight, Propylene / ethylene having an intrinsic viscosity ([η] _H ) of the insoluble part of 1.5 to 2.0 dl / g and an intrinsic viscosity ([η] _EP ) of the soluble part of 1.4 to 2.0 dl / g A block copolymer (b) 40 to 55% by weight, a low density polyethylene polymer (c) 5 to 20% by weight, and a resin composition containing 1500 to 10,000 ppm of a crystal nucleating agent containing a metal phosphate, The tear strength in the longitudinal direction of the film is 30 N / mm or less This can be achieved by forming a polypropylene-based sealant film.

  In the present invention, the crystal nucleating agent preferably contains a metal phosphate and a metal dicarboxylate.

Moreover, in this invention, it is preferable that the density of the said low density polyethylene-type polymer (c) is 0.900-0.940 g / cm < ³ >, and a melt flow rate is 1-10 g / 10min.

  Furthermore, in the present invention, the low density polyethylene polymer (c) is preferably a linear low density polyethylene.

The polypropylene-based sealant film of the present invention preferably has a birefringence in the range of 3.0 × 10 ^{−3 to} 5.0 × 10 ⁻³ .

  The present invention is also a laminate in which a polypropylene-based sealant film is laminated on one side of a base material layer formed by laminating a single layer or two or more layers.

  When used as a sealant for packaging bags, it has excellent easy tearability in the longitudinal direction of the film, excellent heat sealability and low temperature impact resistance, and excellent blocking resistance. It can be used for packaging materials for high retort with excellent properties.

In the propylene / ethylene block copolymer (a) in the present invention, the proportion of the 20 ° C. xylene insoluble part is 75 to 85% by weight, and the intrinsic viscosity ([η] _H ) of the insoluble part is 1.7 to 2.0 dl. / G, and the intrinsic viscosity ([η] _EP ) of the soluble part is required to be 3.0 to 3.4 dl / g. The 20 ° C. xylene insoluble part and the soluble part are the above-mentioned propylene / ethylene block copolymer pellets completely dissolved in boiling xylene, then cooled to 20 ° C., and left for 4 hours or more. When the precipitate and the solution are separated by filtration, the precipitate is referred to as a 20 ° C. xylene insoluble portion, and the portion obtained by drying the solution portion (filtrate) at 70 ° C. under reduced pressure is referred to as the soluble portion. .

When the intrinsic viscosity ([η] _H ) of the insoluble part of the propylene / ethylene block copolymer (a) is less than 1.7 dl / g, the molecular weight of the sea component polypropylene is small, so that low temperature impact resistance and bending resistance are achieved. If the whitening property is insufficient and it is larger than 2.0 dl / g, the molecular weight of polypropylene becomes too large and cast molding becomes difficult. In addition, the intrinsic viscosity ([η] _EP ) of the xylene-soluble part is 3.0 to 3.4 dl / g.

Generally, if the intrinsic viscosity ([η] _EP ) is less than 2.5 dl / g, the blocking resistance such as stickiness of the film may be deteriorated. If it is greater than 3.3 dl / g, polyethylene and ethylene / propylene When the dispersed particle size of the island component composed of the copolymer rubber component is increased and oily food is packaged, a crushed skin phenomenon is likely to occur. In the present invention, by adding a low-density polyethylene polymer (c) to the propylene / ethylene block copolymer (a), a larger amount of the island component composed of the polyethylene polymer component can be finely dispersed. Although it is possible to improve the resistance to generation of crushed skin and the resistance to low-temperature impacts, the seal strength is significantly reduced due to this influence unless the intrinsic viscosity ([η] _EP ) is 3.0 dl / g or more. However, if it exceeds 3.4 dl / g, it will be easy to generate a yuzu skin phenomenon. The xylene-soluble part preferably has an ethylene content in the range of 20 to 50% by weight. If the content is less than 20% by weight, the low-temperature impact resistance at low temperatures may be reduced. Conversely, if the content is more than 50% by weight, easy tearing and blocking resistance may be insufficient.

  As a composition ratio in the resin composition constituting the polypropylene sealant film of the present invention, when the propylene / ethylene block copolymer (a) is less than 35% by weight, the impact resistance and the seal strength are deteriorated. When it increases, the easy tearability deteriorates.

In the propylene / ethylene block copolymer (b), the proportion of the 20 ° C. xylene insoluble part is 85 to 95% by weight, and the intrinsic viscosity ([η] _H ) of the insoluble part is 1.5 to 2.0 dl / g. Yes, and the intrinsic viscosity ([η] _EP ) of the soluble part needs to be 1.4 to 2.0 dl / g. When the proportion of the 20 ° C. xylene-insoluble part is less than 85% by weight, it becomes easy to generate itchy skin and the easy tearing property is deteriorated. On the other hand, when it is more than 95% by weight, the low temperature impact resistance strength is lowered.

Further, when the intrinsic viscosity ([η] _H ) of the insoluble part is less than 1.5 dl / g, the low-temperature impact resistance strength is lowered. When the intrinsic viscosity is more than 2.0 dl / g, the molecular weight of polypropylene is increased. Too much cast molding becomes difficult. The intrinsic viscosity ([η] _EP ) of the xylene-soluble part is 1.4 to 2.0 dl / g. Generally, if it is smaller than 2.5 dl / g, the blocking resistance tends to deteriorate such as a sticky film. However, by limiting the proportion of the 20 ° C. xylene soluble part to 5 to 15% by weight, the above problem is can be solved. However, in the case of less than 1.4 dl / g, there is a concern that even if the proportion of the 20 ° C. xylene soluble part is limited to 5 to 15% by weight, the seal strength is lowered and the blocking resistance is deteriorated.

  As a composition ratio in the resin composition constituting the polypropylene sealant film of the present invention, when the propylene / ethylene block copolymer (b) is less than 40% by weight, easy tearability and blocking resistance are deteriorated, and 55% by weight. If it is more, impact resistance and seal strength will be reduced.

  In addition, as a manufacturing method of the propylene ethylene block copolymer (a) and (b) used for this invention, the method of polymerizing propylene, ethylene, etc. which are raw materials using a catalyst is mentioned. Here, as the catalyst, a Ziegler-Natta type, a metallocene catalyst, or the like can be used. For example, those described in JP-A-07-216017 can be preferably used.

Specifically, (1) in the presence of an organosilicon compound having an Si—O bond and an ester compound, the general formula Ti (OR) _a X _4-a (wherein R is a hydrocarbon group having 1 to 20 carbon atoms) X represents a halogen atom, a represents a number of 0 <a ≦ 4, preferably 2 ≦ a ≦ 4, and particularly preferably a = 4). The resulting solid product is treated with an ester compound, and then treated with a mixture of an ether compound and titanium tetrachloride or a mixture of an ether compound, titanium tetrachloride and an ester compound, to obtain a trivalent titanium compound-containing solid catalyst. And (2) a catalyst system comprising an organoaluminum compound and (3) an electron donating compound (dialkyldimethoxysilane or the like is preferably used).

  Propylene / ethylene block copolymers (a) and (b) are produced mainly from propylene in the first step substantially in the absence of an inert agent from the viewpoint of productivity and low temperature impact resistance. It is preferable to use a method of polymerizing the polymer portion and then polymerizing the ethylene / propylene copolymer in the gas phase in the second step.

  In addition to the propylene / ethylene block copolymers (a) and (b), the polypropylene-based sealant film of the present invention has a sealing property, an impact resistance, and a low-density polyethylene-based polymer (c). Yuzu skin resistance deteriorates.

  Low-density polyethylene polymer (c) can be added, and the low-temperature impact resistance can be improved by increasing the glass transition point component lower than that of the polypropylene-ethylene block copolymer. The amount of scum-resistant skin can be improved by finely dispersing the polymer in a polypropylene / ethylene block copolymer more uniformly.

  In the present invention, the low density polyethylene polymer (c) needs to contain 5 to 20% by weight as a composition ratio in the resin composition constituting the polypropylene sealant film. When the content of the low-density polyethylene polymer (c) is less than 5% by weight, the effect of improving the low temperature impact resistance and the resistance to the generation of crushed skin is not sufficient. Sex worsens.

The density of the low density polyethylene polymer (c) used in the present invention is preferably in the range of 0.900 to 0.940 g / cm ³ . Examples of the polyethylene polymer include ethylene alone or a copolymer of ethylene and an α-olefin having 3 or more carbon atoms such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, etc. Those manufactured by methods known in the art can be used. Specifically, high-pressure low-density polyethylene and linear low-density polyethylene can be used. Among them, linear low-density polyethylene has higher impact strength and higher seal strength than high-pressure low-density polyethylene. Low density polyethylene is preferred.

When the density of such a low density polyethylene polymer is less than 0.900 g / cm ³ , the blocking resistance may be lowered, and when it is higher than 0.940 g / cm ³ , the low temperature impact resistance may be lowered. In addition, it is preferable from the viewpoint of sealing strength to use a metallocene catalyst. Furthermore, the polypropylene-based sealant film of the present invention can satisfy easy tearability by containing a crystal nucleating agent containing a metal phosphate in the range of 1500 ppm to 10000 ppm. If the crystal nucleating agent is less than 1500 ppm, the easy tearability cannot be satisfied, and if it exceeds 10000 ppm, no further improvement in easy tearability is observed. Moreover, although easy tearability can be satisfied even with a metal phosphate alone, it is easier to tear when used in combination with a metal salt of a dicarboxylic acid. Therefore, these crystal nucleating agents are used in combination. More preferred.

  Examples of the phosphoric acid metal salt in the present invention include a phosphoric acid ester compound, and among them, an aromatic phosphoric acid ester metal salt is preferable for the purpose of the present invention. Specifically, sodium-bis (4-t-butylphenyl) phosphate, sodium-bis (4-methylphenyl) phosphate, sodium-bis (4-ethylphenyl) phosphate, sodium-bis (4-i -Propylphenyl) phosphate, sodium-bis (4-t-octylphenyl) phosphate, potassium-bis (4-t-butylphenyl) phosphate, calcium-bis (4-t-butylphenyl) phosphate, magnesium -Bis (4-t-butylphenyl) phosphate, lithium-bis (4-t-butylphenyl) phosphate, aluminum-bis (4-t-butylphenyl) phosphate, sodium-2,2'-methylene- Bis (4,6-di-t-butylphenyl) phosphine Sodium 2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis (4,6-di-t-butylphenyl) Phosphate, lithium-2,2′-ethylidene-bis (4,6-di-tert-butylphenyl) phosphate, sodium-2,2′-ethylidene-bis (4-i-propyl-6-tert-butyl) Phenyl) phosphate, lithium-2,2′-methylene-bis (4-methyl-6-tert-butylphenyl) phosphate, lithium-2,2′-methylene-bis (4-ethyl-6-tert-butyl) Phenyl) phosphate, calcium-bis [2,2′-thiobis (4-methyl-6-tert-butylphenyl) phosphate], calcium-bis [2,2′-thiobi] (4-ethyl-6-tert-butylphenyl) phosphate], calcium-bis [2,2′-thiobis- (4,6-di-tert-butylphenyl) phosphate], magnesium-bis [2,2 '-Thiobis (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2'-thiobis- (4-t-octylphenyl) phosphate], sodium-2,2'-butylidene -Bis (4,6-di-methylphenyl) phosphate, sodium-2,2'-butylidene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2,2'-t-octyl Methylene-bis (4,6-di-methylphenyl) phosphate, sodium-2,2'-t-octylmethylene-bis (4,6-di-t-butylpheny ) Phosphate, calcium-bis [2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2′-methylene-bis (4,6- Di-t-butylphenyl) phosphate], barium-bis [2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate], sodium-2,2′-methylene-bis ( 4-methyl-6-tert-butylphenyl) phosphate, sodium-2,2′-methylene-bis (4-ethyl-6-tert-butylphenyl) phosphate, sodium- (4,4′-dimethyl-5) , 6'-di-t-butyl-2,2'-biphenyl) phosphate, calcium-bis [(4,4-'dimethyl-6,6'-di-t-butyl-2,2'-biphenyl Phosphate], sodium-2,2'-ethylidene-bis (4-m-butyl-6-t-butylphenyl) phosphate, sodium-2,2'-methylene-bis (4,6-di-methylphenyl) ) Phosphate, sodium-2,2'-methylene-bis (4,6-di-ethylphenyl) phosphate, potassium-2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate Fate, calcium-bis [2,2′-ethylidene-bis (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2′-ethylidene-bis (4,6-di-t) -Butylphenyl) phosphate], barium-bis [2,2-'ethylidene-bis (4,6-di-t-butylphenyl) phosphate], aluminum Tris [2,2′-methylene-bis (4,6-di-t-butylfel) phosphate] and aluminum-tris [2,2′-ethylidene-bis (4,6-di-t-butylphenyl) phosphate Fate] and a mixture of two or more of these. Sodium-2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate is particularly preferable.

  The dicarboxylic acid metal salt in the present invention is a compound represented by the following structural formula (i) disclosed in JP-A-2015-212078.

(In Formula (i), M ₁ and M ₂ are sodium, hydrogen, calcium, strontium, or lithium, and may be the same or different. R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are a hydrogen atom, a halogen atom, an alkyl group having 1 to 9 carbon atoms, a hydroxyl group, an alkoxy group having 1 to 9 carbon atoms, or 1 carbon atom. Is an alkyleneoxy group having from 9 to 9, an amino group, an alkylamino group having 1 to 9 carbon atoms, or a phenyl group, and may be the same or different from each other R ² , R ³ , R ⁴ , R Any two of ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are joined together with the cyclohexane ring carbon atom depicted in formula (i) to which they are attached A saturated hydrocarbon ring having 3 to 6 carbon atoms It may also form .R ² and R ³ may be a trans configuration, and may be in the cis configuration.

  As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. are mentioned, for example. Examples of the alkyl group having 1 to 9 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Examples of the alkoxy group having 1 to 9 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group. Examples of the alkylamino group having 1 to 9 carbon atoms include a methylamino group, an ethylamino group, a dimethylamino group, and a diethylamino group. Examples of the alkyleneoxy group having 1 to 9 carbon atoms include groups represented by the following formulas.

R (R'O) n-
(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ′ represents an alkylene group having 2 or 3 carbon atoms, and n represents an integer of 2 to 4, provided that (The total number of carbon atoms of R and R ′ is 9 or less.)
When the alkyleneoxy group having 1 to 9 carbon atoms is a group represented by the above formula, preferably, H (CH ₂ CH ₂ O) ₂ —, H (CH ₂ CH ₂ O) ₃ —, H ( CH ₂ CH ₂ O) ₄ —, CH ₃ (CH ₂ CH ₂ O) ₂ —, CH ₃ (CH ₂ CH ₂ O) ₃ —, CH ₃ (CH ₂ CH ₂ O) ₄ —, CH ₃ CH ₂ ( _{CH 2 CH 2 O) 2 -} , CH 3 CH 2 (CH 2 CH 2 O) 3 -, (CH 3) 2 CH (CH 2 CH 2 O) 2 -, (CH 3) 2 CH (CH 2 CH 2 _{O) 3 -, H ((} CH 3) CHCH 2 O) 2 -, H ((CH 3) CHCH 2 O) 3 -, CH 3 ((CH 3) CHCH 2 O) 2 -, or _CH 3 CH _{2 ((CH 3) CHCH 2 O} ) 2 - a.

  The dicarboxylic acid metal salt is preferably disodium-bicyclo (2,2,1) heptane-2,3-dicarboxylate represented by the following structural formula (ii), or represented by the following structural formula (iii). 1,2-cyclohexanedicarboxylic acid calcium salt is preferred.

  Further, the content of the dicarboxylic acid metal salt according to the present invention is preferably 0 ppm or more and 2000 ppm or less, and more preferably 10 ppm or more and 1000 ppm or less in terms of excellent blocking resistance and low-temperature impact resistance strength. More preferably, it is 50 ppm or more and 1000 ppm or less in terms of excellent easy tearability.

  The present invention may further contain 0 to 5000 ppm of a saccharide nucleating agent. However, since the odor of the film after retort may worsen when there is much content, it is preferably 2000-3000 ppm. At that time, more excellent easy tearability can be satisfied. Sugar nucleating agents include sorbitol, nonitol, xylitol, etc., specifically, bis-1,3: 2,4- (3′-methyl-4′-fluoro-benzylidene) 1-propyl. Sorbitol, bis-1,3: 2,4- (3 ′, 4′-dimethylbenzylidene) 1′-methyl-2′-propenyl sorbitol, bis-1,3,2,4-dibenzylidene 2 ′, 3 ′ Dibromopropyl sorbitol, bis-1,3,2,4-dibenzylidene 2′-bromo-3′-hydroxypropyl sorbitol, bis-1,3: 2,4- (3′-bromo-4′-ethylbenzylidene ) -1-allylsorbitol, mono-2,4- (3′-bromo-4′-ethylbenzylidene) -1-allylsorbitol, bis-1,3: 2,4- (4′-ethylbenzylidene) 1 Allylsorbitol, bis-1,3: 2,4- (3 ′, 4′-dimethylbenzylidene) 1-methylsorbitol, 1,2,3-trideoxy-4,6: 5,7-bis-[(4- Propylphenyl) methylene] -nonitol, bis-1,3: 2,4- (4′-ethylbenzylidene) 1-allylsorbitol, bis-1,3: 2,4- (5 ′, 6 ′, 7 ′, 8'-tetrahydro-2-naphthaldehyde benzylidene) 1-allylxylitol, bis-1,3: 2,4- (3 ', 4'-dimethylbenzylidene) 1-propylxylitol, and the like.

  About the crystal nucleating agent used by this invention, it is better to use it by the masterbatch containing 3 to 10weight% from the problem of dispersibility. The carrier resin of the masterbatch is preferably an olefin resin, for example, a propylene random copolymer obtained by random copolymerization of propylene with ethylene or butene, a homopolypropylene, a propylene block copolymer or a polyethylene resin. .

  Moreover, when using a masterbatch, it is preferable to add and mix the said dispersing agent.

  The polypropylene-based sealant film of the present invention includes an antioxidant, a heat stabilizer, a neutralizing agent, an antistatic agent, a hydrochloric acid absorbent, an antiblocking agent, a lubricant, a nucleating agent, etc., as long as the object of the present invention is not impaired. Can be included. These additives may be used alone or in combination of two or more.

  Here, specific examples of the antioxidant include 4-methyl-2,6-di-t-butylphenol (BHT), octadecyl-3- (3,5-di-t-butyl-4) as hindered phenols. -Hydroxyphenyl) propionate ("Irganox" 1076, "Sumilizer" BP-76), tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane ("Irganox") 1010, “Sumilizer” BP-101), tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (“Irganox” 3114, “Adekastab” AO-20) and the like, and phosphites Tris (2,4-di-t-butylphenyl) phosphat ("Irgafos" 168, "Adekastab" 2112), tetrakis (2,4-di-t-butylphenyl) -4-4'-biphenylene-diphosphonite ("Sandstab" P-EPQ), bis (2,4- Di-t-butylphenyl) pentaerythritol diphosphite (“Ultranox” 626, “Adekastab” PEP-24G), distearyl pentaerythritol diphosphite (“Adekastab” PEP-8), and the like. 2,4,8,10-Tetra-t-butyl-6- [3- (3-methyl-4-hydroxy-5-t-butylphenyl) propoxy having both hindered phenol and phosphite functions ] Dibenz [d, f] [1,3,2] dioxaphosphine ("Sumiliz r "GP) and acrylic acid 2 [1- [2-hydroxy-3,5-di-t-pentylphenyl] ethyl] -4,6-di-t-pentylphenyl (" Sumilizer "GS) are preferred. In particular, the combined use of both is preferable because it exerts an effect in suppressing the decomposition of the 20 ° C. xylene-soluble part and greatly contributes to both low-temperature impact resistance and blocking resistance. When the decomposition of the xylene-soluble part is promoted, the blocking resistance may be deteriorated.

  The addition amount of the antioxidant may be appropriately set in the range of 0.05 to 0.3% by weight, although it depends on the kind of the antioxidant used.

  Further, as the neutralizing agent, hydrotalcite compounds, hydroxylation and the like are preferable for reducing smoke generation during film formation.

  Next, the polypropylene-based sealant film of the present invention can be manufactured by a known film forming method such as a T-die method or a tubular method. It is preferable because it is easy to control the birefringence and crystallinity of the film. Although the film-forming method of the film of the present invention by the T-die method will be described below, it is not limited to this method.

  For example, propylene / ethylene block copolymer (a) and (b), low density polyethylene (c) pellets or powder, and metal phosphate and metal dicarboxylate are specified in a uniaxial or biaxial melt extruder. After kneading and kneading at the blending ratio, the obtained kneaded product is filtered through a filter and extruded from a flat die (for example, T die) into a film shape. The temperature of the molten polymer extruded from the melt extruder is usually 180 to 300 ° C., but 200 to 270 ° C. is preferable in order to prevent the polymer from being decomposed and to obtain a good quality film. The film extruded from the T-die is brought into contact with a cooling roll set at a constant temperature of 20 to 90 ° C., cooled and solidified, and then wound up.

  The polypropylene-based sealant film of the present invention can be stretched after cooling and solidification, but is preferably an unstretched film that is not substantially stretched. An unstretched film that is not substantially stretched is preferred because it is not necessary to excessively increase the heat seal temperature during heat sealing (it can be heat-sealed at a relatively low temperature). Moreover, in this invention, although an unstretched film refers to an extrusion cast film, in an actual film forming process, the longitudinal direction (henceforth abbreviated as MD direction) or the width direction (henceforth TD direction) of a film. The birefringence of the unstretched film in the present invention (difference in refractive index between the longitudinal direction and the width direction of the film, Δn) is 0.005 or less. Is preferable in terms of heat sealability and thermal dimensional stability. The birefringence (Δn) can be obtained as Δn = R / d from the film thickness d (nm) of the measurement part by measuring the retardation R (nm) of the sample using the compensator method. it can.

  The thickness of the film of the present invention thus obtained is preferably 20 to 300 μm, more preferably 40 to 100 μm.

  Here, as a method for controlling the birefringence in the present invention, for example, the mixed resin is melted at a low temperature of 180 ° C. to 270 ° C., preferably 200 ° C. to 250 ° C., and the temperature is 50 to 90 ° C., preferably Can be cooled on a casting drum maintained at a high temperature of 50 to 70 ° C. and wound at a speed of 10 to 100 m / min.

  The tear strength in the MD direction of the film obtained as described above is preferably 30 N / mm or less, more preferably in the range of 10 to 25 N / mm. Good, impact resistance and sealing strength are also high and preferable.

  The polypropylene-based sealant film of the present invention can be used alone as a packaging film, but can be preferably used as a sealant film for a retort food packaging bag containing a general Al foil. As a constituent film of the laminate, a normal dry laminating method can be suitably employed that uses an adhesive, but if necessary, for laminating the polypropylene-based unstretched film of the present invention and another base material layer directly. A method of extruding and laminating a polyethylene resin or polypropylene resin can also be employed. These laminates are used after being made into bags in a flat bag, a standing pouch, etc., using the polypropylene-based unstretched film as a seal layer (inner surface of the bag).

  In addition, the laminated structure of these laminates has the required characteristics of packaging bags (for example, barrier performance to satisfy the quality retention period of the food to be packaged, size / low temperature impact resistance that can cope with the weight of the contents, visual recognition of the contents) Depending on the nature and the like).

  Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited thereto. Moreover, the detailed description of this invention and the measured value of each evaluation item in an Example were measured with the following method.

(1) Content of 20 ° C. xylene soluble part 5 g of polypropylene pellets are completely dissolved in 500 mL of boiling xylene (Kanto Chemical Co., Ltd. Grade 1), then cooled to 20 ° C. and left for 4 hours or more. Thereafter, this was filtered into a precipitate and a solution, and separated into a soluble part and an insoluble part. The soluble part solidified the filtrate under reduced pressure, dried at 70 ° C., and measured its weight to determine the content (% by weight).

(2) Intrinsic viscosity of 20 ° C. xylene insoluble part and soluble part Using the sample separated by the above method, measurement was performed in 135 ° C. tetralin using an Ubbelohde viscometer.

(3) Melt flow rate (MFR)
According to JIS K7210: 1999, the propylene / ethylene block copolymer was measured at a temperature of 230 ° C., and the polyethylene-based polymer was measured at a temperature of 190 ° C. under a load of 21.18 N, respectively.

(4) Density The density was measured by a measuring method using a density gradient tube based on JIS K7112: 1999.

(5) Low-temperature impact resistance PET of 12 μm thickness, ON of 15 μm thickness, Al foil of 9 μm thickness and the film of the present invention are bonded together by a normal dry laminating method using a urethane-based adhesive. A laminate with a configuration was created.
Laminate structure: PET / adhesive / ON / adhesive / Al foil / adhesive / film of the present invention The two sheets of this laminate were used as the inner surface of the bag, and the CA- Using a 450-10 type heat sealer, a standing pouch having a bag size of 150 mm × 285 mm was prepared with a heating time of 1.4 seconds (sealing temperature: about 220 ° C.) and a cooling time of 3.0 seconds. The bag is filled with 1000 cm ³ of 0.1% saline solution, and then retorted at 135 ° C. for 30 minutes. After storing the bag after the retort treatment in a refrigerator at 0 ° C., it is dropped from a height of 55 cm onto a flat floor (n number: 20), and the number of times until the bag is broken is recorded. In this evaluation method, if the average value of n number of 20 is 15 times or more, the low temperature impact resistance for business use is considered good.

(6) Heat-sealing strength Heat-sealing two sealing layers of the same laminate as in (5) using a flat plate heat sealer under conditions of a sealing temperature of 180 ° C., a sealing pressure of 10 N / cm ² , and a sealing time of 1 second. The sample was retorted at 130 ° C. for 30 minutes, and then heat seal strength was measured at a tensile speed of 300 mm / min using Tensilon manufactured by Orientec Corporation. If the seal strength is 45 N / 15 mm or more in this measurement method, it can be used well for retort applications.

(7) Scratch-resistant skin generation 12 μm thick PET, 15 μm thick ON, 9 μm thick Al foil and the film of the present invention are bonded together by a normal dry laminating method using a urethane-based adhesive. A laminate having a thickness of 115 μm was prepared.
Laminate structure: PET / adhesive / ON / adhesive / Al foil / adhesive / film of the present invention Two sheets of this laminate were used so that the film of the present invention was the inner surface of the bag and a flat plate heat sealer was used. And heat sealing under conditions of a sealing temperature of 180 ° C., a sealing pressure of 10 N / cm ² , and a sealing time of 1 second to produce a three-sided bag (flat bag, seal width of 5 mm) having a size of 160 mm × 210 mm (internal dimensions) . After filling this bag with a commercially available retort curry (Retort Curry “Kukure Curry / Dry” manufactured by House Foods Industries Co., Ltd.), the state of unevenness on the surface of the laminate immediately after retorting at 135 ° C. for 30 minutes was visually determined. The rating was evaluated as rank 1 for those that did not occur at all, rank 2 for those that occurred slightly, rank 3 for those that slightly occurred, rank 4 for those that occurred clearly, and rank 5 that occurred severely. In this evaluation method, ranks 1 and 2 were evaluated as good for the generation of scum skin.

(7) Blocking shear force A film sample having a width of 30 mm and a length of 100 mm is prepared, the films are overlapped in a range of 30 mm × 40 mm, a load of 5 N / 12 cm ² is applied, and the film is 2.0 in an oven at 80 ° C. After heat treatment for a period of time, the plate was allowed to stand for 30 minutes or more in an atmosphere of 23 ° C. and 65% humidity, and then the shear peeling force was measured at a tensile speed of 300 mm / min using Tensilon manufactured by Orientec. If the shear peeling force is 10 N / 12 cm ² or less in this measurement method, it can be used after non-powder retort.

(8) Tear strength Based on JIS K7128-1: 1998 (trouser tear method), in a constant temperature room at 23 ° C., a test piece having a width of 50 mm (TD) and a length of 150 mm (MD) is cut into the center of a strip having a length of 75 mm. The tear strength (N) in the MD direction was measured at a speed of 200 mm / min, and the tear strength was calculated by dividing by the thickness (mm) of the film. If it was 30 / mm or less, it was judged that it had easy tearability. MD is the longitudinal direction of the film, and TD is the width direction of the film.

(9) Birefringence (△ n)
Using a POH polarizing microscope manufactured by Nippon Optical Co., Ltd., the light source was measured as a white light by a normal compensator method. A (MD) 50 mm × (TD) 30 mm film sample is prepared and set on the stage of a deflection microscope. Insert the analyzer, set the scale of the compensator to 30, and make it a dark field. Rotate the stage 45 degrees to the right or left. Rotate the compensator toward the number larger than 30 and the scale of the compensator when the appearing shadow is centered is (a), rotate the compensator toward the number smaller than 30 and the appearing shadow is located in the center The time scale of the compensator is measured as (b), and each is measured (read to 1/10 of the minimum scale). Further, the compensator is returned to 30, the analyzer is removed, the thickness d of the sample is measured, and the birefringence (Δn) is calculated based on the following formula (however, the arithmetic average value of 20 measurements is taken as the measurement value).
Δn = T / d (T = nλ ₀ + ε)
λ ₀ = 589.3 μm (where ε is determined from C / 1000 and i in the rights compensator manual and i; i; (ab) (difference in compensator reading)).

  Each component used in Examples and Comparative Examples is as follows.

[Propylene / ethylene block copolymer (a) / B-PP1]
The content of the 20 ° C. xylene insoluble part is 80% by weight, its intrinsic viscosity ([η] _H ) is 1.90 dl / g, the content of the 20 ° C. xylene soluble part is 20% by weight, its intrinsic viscosity ([η] _EP ) is 3.20 dl / g, MFR at 230 ° C. is 2.3 g / 10 min, and propylene / ethylene block copolymer pellets containing “Sumilizer” GP 300 ppm and “Sumilizer” GS 750 ppm as antioxidants are used. did. Hereinafter, the propylene / ethylene block copolymer (a) is referred to as B-PP1.

[Propylene / ethylene block copolymer (b) / B-PP2]
The content of the 20 ° C. xylene insoluble part is 88% by weight, its intrinsic viscosity ([η] _H ) is 1.60 dl / g, the content of the 20 ° C. xylene soluble part is 12% by weight, its intrinsic viscosity ([η] _EP ) is 1.80 dl / g of propylene / ethylene block copolymer as dicarboxylic acid metal salt, disodium-bicyclo (2,2,1) heptane-2,3-dicarboxylate (available from Milliken Chemical) Propylene with an MFR of 8.0 g / 10 min containing "HYPERFORM" (registered trademark) HPN-68L) 2,000 ppm, "Sumilizer" (registered trademark) GP 300 ppm and "Sumizer" (registered trademark) GS750 ppm as antioxidants -Ethylene block copolymer pellets were used. Hereinafter, it is referred to as B-PP2.
[Propylene / ethylene block copolymer (b) / B-PP3]
The content of the 20 ° C. xylene insoluble part is 88% by weight, its intrinsic viscosity ([η] _H ) is 1.60 dl / g, the content of the 20 ° C. xylene soluble part is 12% by weight, its intrinsic viscosity ([η] _EP ) was 1.80 dl / g, MFR was 8.0 g / 10 min, and propylene / ethylene block copolymer pellets containing “Sumilizer” GP 300 ppm and “Sumilizer” GS 750 ppm as antioxidants were used. Hereinafter, the propylene / ethylene block copolymer (b) is referred to as B-PP3.

[Low density polyethylene polymer (c) / low density PE]
Linear low-density polyethylene (GA401 manufactured by Sumitomo Chemical Co., Ltd.) having a density of 0.935 g / cm ³ , MFR of 3.0 g / 10 min and a copolymerization component of 1-butene was used. The low density polyethylene polymer (c) is referred to as low density PE.

[Crystal nucleating agent of metal phosphate / MB1]
Contains 6% by weight of a nucleating agent of sodium-2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate (“ADEKA STAB” NA-11 manufactured by ADEKA), which is a metal phosphate ester A master batch (PPMST-0024 manufactured by Tokyo Ink, Carrier Resin: Homopolypropylene, MFR: 7 g / 10 min) was used. Hereinafter, the crystal nucleating agent master batch of the phosphate ester metal salt is referred to as MB1.

[Examples 1 to 5]
In the resin composition shown in Table 1, mixed in a pellet state by a blender, supplied to an extruder, melt-kneaded, filtered through a filter, then extruded at 240 m from a T-die at 60 m / min, and contacted a 50 ° C. cooling roll After cooling and solidifying, one side was subjected to corona discharge treatment to obtain a film having a thickness of 70 μm.

  As a result of evaluating the film properties, as shown in Table 1, a film satisfying a good balance in terms of tear strength, low temperature impact resistance, Δn, blocking shear force, crushed skin resistance, and seal strength was obtained, particularly as a sealant for packaging bags. It has been confirmed that it can be used as a non-powder because it has excellent easy tearability in the resin flow direction (MD) and is excellent in blocking resistance.

[Comparative Examples 1-5]
In the resin composition shown in Table 1, mixed in a pellet state by a blender, supplied to an extruder, melt-kneaded, filtered through a filter, then extruded at 240 m from a T-die at 60 m / min, and contacted a 50 ° C. cooling roll After cooling and solidifying, one side was subjected to corona discharge treatment to obtain a film having a thickness of 70 μm.

  In Comparative Example 1, the low-temperature impact property and the seal strength were insufficient.

  Comparative Examples 2 and 3 were not easily tearable and blocking, and could not be suitably used for high retort applications.

  In Comparative Example 4, the low-temperature impact property and the seal strength were insufficient.

  In Comparative Example 5, the easy tear strength was very poor.

Claims (6)

The proportion of the 20 ° C. xylene insoluble part is 75 to 85% by weight, the intrinsic viscosity ([η] _H ) of the insoluble part is 1.7 to 2.0 dl / g, and the intrinsic viscosity of the soluble part ([η] _EP ) Is 3.0 to 3.4 dl / g of propylene / ethylene block copolymer (a) 35 to 45% by weight, the proportion of 20 ° C. xylene insoluble part is 85 to 95% by weight, the limit of the insoluble part Propylene / ethylene block copolymer having a viscosity ([η] _H ) of 1.5 to 2.0 dl / g and an intrinsic viscosity ([η] _EP ) of the soluble part of 1.4 to 2.0 dl / g ( b) comprising a resin composition containing 40 to 55% by weight, a low density polyethylene polymer (c) 5 to 20% by weight, and 1500 to 10,000 ppm of a crystal nucleating agent containing a metal phosphate, and tearing in the longitudinal direction of the film The strength is 30 N / mm or less. Repropylene sealant film.   The polypropylene-based sealant film according to claim 1, wherein the crystal nucleating agent contains a metal phosphate and a metal dicarboxylate. The polypropylene sealant film according to claim 1 or 2, wherein the density of the low density polyethylene polymer (c) is 0.900 to 0.940 g / cm ³ and the melt flow rate is 1 to 10 g / 10 min.   The polypropylene-based sealant film according to any one of claims 1 to 3, wherein the low-density polyethylene-based polymer (c) is a linear low-density polyethylene. The polypropylene-based sealant film according to any one of claims 1 to 4, wherein the birefringence is in the range of 3.0 x ^{10-3 to} 5.0 x ^10-3 .   The laminated body by which the polypropylene-type sealant film in any one of Claims 1-6 was laminated | stacked on the single side | surface of the base material layer formed by laminating | stacking the film of a single layer or 2 layers or more.