JP6302726B2 - Biaxially stretched polypropylene film and packaging bag - Google Patents

Description

  The present invention relates to a biaxially stretched polypropylene film excellent in hot tack property and heat sealability, and a packaging bag obtained from the film.

Fruits and vegetables such as raw vegetables, fruits, persimmons, and mushrooms are packaged and distributed in a bag-shaped resin film to maintain freshness and protect them from damage caused by contact with the outside. As the resin film, a polypropylene film is generally used because of its excellent transparency, gloss and rigidity.
A packaging machine such as a vertical pillow machine is used as an apparatus for processing this resin film into a bag shape and automatically packaging fruits and vegetables such as raw vegetables. With a vertical pillow machine, first the resin film is made into a cylinder, the bottom of the bag is sealed, the contents are put in from the top of the bag, and finally the top of the bag is sealed, so that the contents are packaged in a bag-like resin film. It is a device to do.

  As a film for automatically packaging such fruits and vegetables, for example, two layers of a layer containing a propylene homopolymer having an NMR pentad fraction of 93 to 98% and a layer containing a propylene random copolymer and a polyethylene resin are used. A biaxially stretched polypropylene film has been proposed that has excellent antifogging properties and fusing seal strength, and can be stably bag-formed even at high speed (see Patent Document 1).

  However, if a load of the contents is applied to the seal part (bottom part of the bag) immediately after the seal, there is a possibility that in the case of a heavy object such as raw vegetables, a problem such as the opening of the seal part may occur.

JP 2007-253349 A

  The main subject of this invention is providing the novel biaxially-stretched polypropylene film for packaging excellent in the heat seal intensity | strength and the hot tack property at the time of the filling of the contents. Another object of the present invention is to provide a packaging bag obtained from such a film.

  As a result of intensive studies, the present inventors have used a mixed resin containing a certain proportion of a propylene-based random copolymer and a polyethylene-based resin in the seal layer, thereby providing excellent biaxiality in transparency and hot tack. It was discovered that a stretched polypropylene film could be obtained, and the present invention was completed.

  Examples of the present invention include the following.

[1] A biaxially stretched polypropylene film having at least three layers of a surface layer, a base material layer, and a seal layer, wherein the seal layer contains 75 to 93% by weight of a propylene random copolymer and a polyethylene resin. A biaxially stretched polypropylene film characterized by containing 7 to 25% by weight.

[2] The surface layer contains 50 to 99% by weight of a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. and 1 to 50% by weight of a crystalline polypropylene resin having a melting point of 166 ° C. to 175 ° C. 1] The biaxially stretched polypropylene film described in [1].

[3] having a melting point of 166 ° C. to 175 ° C. of the crystalline polypropylene ^{resin, 13} C nuclear magnetic resonance spectrum by isotactic pentad fraction (IP) is that 97.0% or more, according to the above [2] Biaxially oriented polypropylene film.

[4] The biaxially stretched polypropylene film according to any one of [1] to [3], wherein the base material layer contains an antifogging agent.

[5] A packaging bag produced using the biaxially stretched polypropylene film according to any one of [1] to [4].
[6] The packaging bag according to [5], which is for packaging fruits and vegetables.

  According to the biaxially stretched polypropylene film for packaging of the present invention, since the heat seal strength is excellent and the hot tack property at the time of filling the content is excellent, even if the content is a relatively heavy thing such as raw vegetables, the sealing portion Is difficult to open, and can be efficiently packaged using, for example, a vertical pillow packaging machine.

I. About the biaxially stretched polypropylene film of the present invention The biaxially stretched polypropylene film of the present invention (hereinafter referred to as “the film of the present invention”) has at least three layers: a surface layer, a base material layer, and a seal layer.

I-1. First, the sealing layer according to the film of the present invention will be described. For example, when packaging fruits and vegetables with a vertical pillow machine, the sealing layer is a layer that becomes the inside of the cylinder when the resin film is first formed into a cylindrical shape, and the sealing layers adhere to each other at the sealing portion.
The seal layer contains a propylene random copolymer and a polyethylene resin.

  The propylene random copolymer is a copolymer of propylene and other α-olefin. Examples of such α-olefins other than propylene include α-olefins other than propylene having 2 to 20 carbon atoms, and specifically include, for example, ethylene, 1-butene, 1-pentene, and 1-hexene. 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 3-methyl-1-butene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, -Eicosene, cyclopentene, cycloheptene, norbornene, 5-ethyl-2-norbornene, tetracyclododecene, 2-ethyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8, Examples include 8a-octahydronaphthalene. Among these, C2-C4, for example, ethylene and butene are preferable, and ethylene is more preferable. These α-olefins other than propylene may be one kind or a combination of two or more kinds.

  The content of α-olefin other than propylene in the propylene random copolymer is preferably 14% by weight or less, and more preferably 10% by weight or less.

  The propylene random copolymer is not particularly limited as long as it is a random copolymer of propylene and other α-olefins. Specifically, for example, propylene-ethylene random copolymer, propylene-butene A random copolymer, a propylene-ethylene-butene random copolymer, etc. can be mentioned. Among these, a propylene-ethylene-butene random copolymer is preferable.

  Among the propylene-based random copolymers, the melt flow rate (MFR) value when measured under conditions of 230 ° C. and 21.18 N (2.16 Kg) load in accordance with ISO 1133 (1997) is 0.5 to A propylene random copolymer within the range of 20 g / 10 min is preferred. Further, a propylene random copolymer having a melt flow rate value in the range of 4 to 8 g / 10 min is more preferable. The melt flow rate (MFR) value of the polymer can be appropriately adjusted depending on the type and content of α-olefin other than propylene, the molecular weight of the polymer, and the degree of polymerization.

  The polyethylene resin according to the present invention is a copolymer of ethylene and other α-olefins. Examples of such α-olefins other than ethylene include α-olefins having 3 to 20 carbon atoms. Specific examples include propylene, 1-butene, 3-methyl-1-butene, 3- Methyl-1-pentene, 4-methyl-1-pentene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. Is mentioned. Among these, C3-C8, for example, 1-hexene, 4-methyl-1-pentene, and 1-octene are preferable. These α-olefins other than ethylene may be used alone or in combination of two or more.

  As a content ratio of ethylene and the other α-olefin in the polyethylene-based resin, ethylene is usually 75 to 100% by weight, and other α-olefins are 0 to 25% by weight, preferably ethylene is 85% by weight. ˜99.9 wt%, other α-olefin is 0.1 to 15 wt%, more preferably 90 to 99.5 wt%, and other α-olefin is 0.5 to 10 wt% %, More preferably 90 to 99% by weight of ethylene and 1 to 10% by weight of other α-olefins.

Among the polyethylene-based resins, the melt flow rate (MFR) value measured at 190 ° C. and 21.18 N (2.16 Kg) load in accordance with ISO 1133 (1997) is 0.5 to 20 g / 10 min. Polyethylene resins that are within the range are preferred. Moreover, the polyethylene-type resin whose said melt flow rate value exists in the range of 2-4 g / 10min is more preferable.
Further, among the polyethylene resins, a polyethylene resin having a density in the range of 0.85 to 0.90 g / cm ³ when measured in accordance with JIS K 7112 is preferable, and 0.86 to 0.89 g / A polyethylene-based resin that is in the range of cm ³ is more preferable.

  The content of the propylene random copolymer and the polyethylene resin in the seal layer is usually 75 to 93% by weight for the propylene random copolymer and 7 to 25% by weight for the polyethylene resin, preferably propylene. 80 to 90% by weight of the random copolymer and 10 to 20% by weight of the polyethylene resin, more preferably 80 to 85% by weight of the propylene random copolymer and 15 to 20% by weight of the polyethylene resin. is there. If the content of the polyethylene resin is less than 7% by weight, sufficient heat seal strength may not be obtained. If the content of the polyethylene resin is more than 25% by weight, the hot tack property may be deteriorated. .

  The sealing layer may contain an antiblocking agent or a lubricant so long as the surfaces of the resin films are smooth and prevent the resin films from adhering to each other as long as the transparency is not impaired. Examples of such an anti-blocking agent include generally used inorganic silica, kaolin, zeolite, or organic crosslinked acrylic beads. Examples of the lubricant include calcium stearate. Only one type of anti-blocking agent and lubricant may be used, or two or more types may be used in combination.

  The addition amount of the anti-blocking agent or lubricant can be appropriately adjusted depending on the type of resin, etc., but 0.05 to 30 parts by weight is appropriate for 100 parts by weight of the resin constituting the layer, preferably 0.5 to 20 parts by weight.

I-2. Surface layer according to the film of the present invention Next, the surface layer will be described. The surface layer is a layer that becomes an outer surface when the resin film is formed into a packaging bag, and is necessary for the purpose of protecting the base material layer from heat when it is formed into a film shape using a mold. The surface layer contains a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. and a crystalline polypropylene resin having a melting point of 166 ° C. to 175 ° C.

  The crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. is a propylene homopolymer or a copolymer of propylene and other α-olefin. Examples of α-olefins other than propylene include α-olefins other than propylene having 2 to 10 carbon atoms. Specific examples include ethylene, 1-butene, 1-pentene, 1-hexene and the like. Can be mentioned. Among these, C2-C4, for example, ethylene and 1-butene are preferable and ethylene is more preferable. These α-olefins other than propylene may be one kind or a combination of two or more kinds. The content of α-olefin other than propylene is suitably 1.3% by weight or less, preferably 0.5% by weight or less.

  Among the crystalline polypropylene resins having a melting point of 155 ° C. to 165 ° C., the melt flow rate (MFR) when measured under the conditions of 230 ° C. and 21.18 N (2.16 Kg) load in accordance with ISO 1133 (1997) The value is preferably in the range of 0.5 to 20 g / 10 min. Further, a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. in which the melt flow rate value is in the range of 2 to 4 g / 10 minutes is more preferable. The melt flow rate (MFR) value of the polymer can be appropriately adjusted depending on the type and content of α-olefin other than propylene, the molecular weight of the polymer, and the degree of polymerization.

Further, among the crystalline polypropylene resins having a melting point of 155 ° C. to 165 ° C., those having an isotactic pentad fraction (IP) of 94.0% to 96.0% by ¹³ C nuclear magnetic resonance spectrum are preferable. .

  The crystalline polypropylene resin having a melting point of 166 ° C. to 175 ° C. according to the present invention is preferably a propylene homopolymer. Among them, the melt flow rate (MFR) value measured in the condition of 230 ° C. and 21.18 N (2.16 Kg) load in accordance with ISO 1133 (1997) is within a range of 0.5 to 20 g / 10 minutes. More preferred are those in the range of 1 to 4 g / 10 min.

Further, among crystalline polypropylene resins having a melting point of 166 ° C. to 175 ° C., those having an isotactic pentad fraction (IP) of 97.0% or more by ¹³ C nuclear magnetic resonance spectrum are preferred, and 98% to What is 99.5% is more preferable.

  As the content of the crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. and the crystalline polypropylene resin having a melting point of 166 ° C. to 175 ° C. in the surface layer, the crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. is usually 50 1 to 50% by weight of a crystalline polypropylene resin having a melting point of 166 ° C. to 175 ° C., preferably 80 to 99% by weight of a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. The crystalline polypropylene resin having a melting point of ˜175 ° C. is 1 to 20% by weight, more preferably the crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. is 90 to 95% by weight and the melting point of 166 ° C. to 175 ° C. The resin is 5 to 10% by weight.

  The surface layer may contain an anti-blocking agent or a lubricant so long as the surfaces of the resin films are smooth and prevent the resin films from adhering to each other as long as the transparency is not impaired. Preferred types and addition amounts of the antiblocking agent or lubricant are the same as those described in the seal layer.

I-3. Base layer according to the present invention the film will now be described base layer. The base material layer is an intermediate layer sandwiched between the seal layer and the surface layer. The base material layer contains a crystalline polypropylene resin as a main component.

The crystalline polypropylene resin is not particularly limited as long as it is a crystalline propylene resin, but a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. is preferable. Examples of the crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. include those similar to the crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. in the surface layer.
The main component is usually a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. in the base material layer of 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. is there.

  The base material layer can contain an antifogging agent for the purpose of imparting antifogging performance to the film. Such an antifogging agent is generally added to the base material layer. However, after film formation of the present invention, it diffuses into the surface layer and the sealing layer, so it is used for packaging high moisture content. When it is applied, good antifogging properties are exhibited. Such an antifogging agent is not particularly limited as long as it meets the purpose, and an antifogging agent conventionally used for an antifogging film can be used as it is. Specifically, for example, three systems of alkyldiethanolamine, alkyldiethanolamine fatty acid ester, and glycerin fatty acid ester can be mentioned.

  The alkyl group in the alkyldiethanolamine is usually one having 8 to 22 carbon atoms, preferably 12 to 18 carbon atoms. Specific examples of the alkyldiethanolamine include lauryl diethanolamine, myristyl diethanolamine, palmityl diethanolamine, stearyl diethanolamine, and oleyl diethanolamine.

  The fatty acid ester group in the alkyldiethanolamine fatty acid ester is usually a saturated or unsaturated fatty acid ester having 8 to 22 carbon atoms, preferably 12 to 22 carbon atoms, and preferably the latter unsaturated fatty acid ester. Specific alkyl diethanolamine fatty acid esters include lauryl diethanolamine monostearate, myristyl diethanolamine monooleate, lauryl diethanolamine monostearate, palmityl diethanolamine monostearate, stearyl diethanolamine monopalmitylate, stearyl diethanolamine monoester. Examples thereof include stearic acid ester and oleyl diethanolamine monostearic acid ester.

  Examples of the fatty acid ester group in the glycerin fatty acid ester include the same fatty acid ester groups as in the above alkyldiethanolamine fatty acid ester. Further, the number of fatty acid ester groups bonded to —OH of glycerin is preferably 1 or 2, more preferably 1 fatty acid ester monoglyceride.

  Each of the above antifogging agents is used in the form of one kind or a mixture of two to three kinds in the same system, and a mixture of two or three kinds in a different kind. It is more preferable to use a mixture of three types, that is, a three-component mixture of an alkyldiethanolamine, an alkyldiethanolamine fatty acid ester and a fatty acid ester monoglyceride, and the alkyldiethanolamine fatty acid ester as a main component.

  The addition amount of the antifogging agent may be appropriately adjusted depending on the type of the antifogging agent and the like, but is suitably 5000 to 15000 ppm, and preferably 4000 to 10,000 ppm. If the addition amount of the antifogging agent is less than 5000 ppm, a sufficient antifogging effect may not be obtained, and if it exceeds 15000 ppm, bleeding to the surface may occur more than necessary, and transparency may be deteriorated.

I-4. Invention Film The invention film has at least three layers of a surface layer, a base material layer, and a seal layer. When each of the layers is formed into a packaging bag, the outer surface is a surface layer, an intermediate layer. Is the base material layer, and the inner side is the sealing layer.

The thickness of each layer in the film of the present invention is as follows.
When the total thickness of the film is in the range of 10 to 80 μm, preferably in the range of 10 to 40 μm, the sealing layer is in the range of 1.5 to 12 μm, preferably in the range of 2 to 6 μm. The layer is in the range of 7-40 μm, preferably in the range of 10-25 μm, and the surface layer is in the range of 1-5 μm, preferably in the range of 1-3 μm. When the thickness of the sealing layer and the surface layer is within this range, it is preferable because the film has good sealing strength and is easy to handle.

An appropriate amount of various additives can be further mixed in the film of the present invention. Examples of such additives include nucleating agents, antioxidants, flame retardants, antistatic agents, fillers, and pigments.
Moreover, this invention film may have other layers, such as an openability provision layer and a gas barrier property provision layer other than the said 3 layers.

  The production method of the film of the present invention is not particularly limited and a known method can be used. However, in consideration of productivity and physical properties of the completed film, a flat sheet is formed by extrusion, and then sequentially biaxially. The film of the present invention is preferably produced by stretching.

  More specifically, the resin constituting the surface layer, the resin constituting the base material layer, and the resin constituting the seal layer are respectively charged into three extruders set at appropriate temperatures, and the resin is contained in the extruder. After being melted and kneaded, it is extruded into a sheet form from a T die at 210 ° C to 250 ° C. In this case, a feed block system or a multi-manifold system may be used to form a three-layer structure. The extruded sheet is cooled and solidified by a cooling roll at 25 ° C. and sent to the longitudinal stretching step. The longitudinal stretching is constituted by a heated roll set at 130 ° C. to 140 ° C., and is stretched in the longitudinal direction (hereinafter referred to as MD direction) due to the speed difference between the rolls. There are no particular restrictions on the number of heating rolls, but at least two heating rolls on the low speed side and the high speed side are necessary. The draw ratio of longitudinal drawing is 4 to 6 times, preferably 4.5 to 5.5 times. Next, it is sent to a transverse stretching step by a tenter and stretched in the transverse direction (hereinafter referred to as TD direction). The tenter is divided into preheating, stretching, and annealing zones. The preheating zone is set to 165 ° C to 170 ° C, the stretching zone is set to 165 ° C to 170 ° C, and the annealing zone is set to 165 ° C to 170 ° C. The stretching ratio in the stretching zone is preferably about 6 to 10 times. After being stretched, it is cooled and fixed in an annealing zone, and then wound up by a winder to form a film roll.

In the production of the film of the present invention, after leaving the annealing zone of the tenter, it is preferable to perform a known surface treatment such as corona discharge treatment, flame treatment, ultraviolet irradiation treatment and the like before winding with a winder. In particular, it is preferable to perform a corona discharge treatment. By performing the surface treatment, the film surface can be given a wetting tension to enhance the antifogging effect, and the adhesion to the printing ink when printing on the film surface can also be improved. In this corona discharge treatment, both the surface layer surface and the seal layer surface may be treated, or one of the surface layer surface and the seal layer surface may be treated. The strength of the corona discharge treatment is preferably in the range of 1.8 × 10 ^{2 to} 9.0 × 10 ² J / m ^2. May be.

  The wetting tension of the surface of the biaxially stretched polypropylene film (present film) thus obtained is preferably 38 to 44 mN / m. When the wetting tension is less than 38 mN / m, the antifogging property is not sufficiently exhibited, and in the case of printing, the adhesiveness of the printing ink is inferior. If the wetting tension exceeds 44 mN / m, the anti-fogging agent bleeds out to the surface, causing whitening and blocking, and also causing a decrease in the fusing seal strength.

II. Next, the packaging bag obtained from the film of the present invention (hereinafter referred to as “the packaging bag of the present invention”) will be described in detail.

The packaging bag of the present invention can be formed using the film of the present invention by an automatic packaging machine or the like.
The film of the present invention is particularly suitable for forming a packaging bag with a vertical pillow packaging machine because it has excellent hot tack at the time of filling the contents, but when forming with a packaging machine such as a horizontal pillow packaging machine. Can also be used.

  The contents to be packaged in the packaging bag of the present invention are not particularly limited as long as they can be packaged. Agricultural products are preferred. Such agricultural products include, for example, vegetables such as leek, sprouts, spinach, broccoli and peppers; cut vegetables such as cabbage, lettuce and carrot; or fruits such as strawberries, bananas and lemons; Examples include mushrooms such as salmon and shiitake mushrooms. Of these, sprouts and cut vegetables are preferred.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

The raw materials used are as follows.
PP-1: propylene-ethylene copolymer (ethylene component: 0.5% by weight, MFR: 3.0 g / 10 min, melting point: 161 ° C., density: 0.9 g / cm ³ )
PP-2: propylene homopolymer (IP = 98%, MFR: 1.9 g / 10 min, melting point: 167 ° C., density: 0.9 g / cm ³ )
PP-3: propylene-ethylene copolymer (ethylene component: 0.4% by weight, MFR: 2.3 g / 10 min, melting point: 160 ° C., density: 0.9 g / cm ³ )
PP-4: propylene-ethylene-butene copolymer (ethylene component: 3.4% by weight, butene component: 1.4% by weight, MFR: 5.0 g / 10 min, melting point: 125 ° C., density: 0.9 g / Cm ³ )
PE-1: linear low density polyethylene (MFR: 3.5 g / 10 min, melting point: 60 ° C., density: 0.88 g / cm ³ )
Antifoggant: Mixture of 15.6% by weight stearyl monoglyceride, 76.9% by weight stearyl diethanolamine monostearate, and 7.5% by weight stearyl diethanolamine

Each physical property in Examples and Comparative Examples is measured as follows.
[Heat seal strength]
After the two films are stacked so that the seal layer faces each other, they are heated with a heat seal tester (HG-100, manufactured by Toyo Seiki Seisakusho) under conditions of a temperature of 130 ° C., a pressure of 0.2 MPa, and a seal time of 1.0 second. Sealed. The obtained sample was cut into a length of 200 mm and a width of 15 mm, and heat-seal strength was measured in a T-shaped peel test using a peel tester (Peeling TSTER HEIDON-17 manufactured by Shinto Kagaku Co., Ltd.) at a tensile rate of 200 mm / min. It was measured. The measurement was performed 5 times and the average value was taken. Those having a seal strength of 4.5 N / 15 mm or more were assumed to withstand actual use.
[Hot tackiness]
Two films are cut into 25 mm × 300 mm strips, and 17.8 g of weight is attached to one end. The two films are overlapped so that the sealing layer surfaces of the two films face each other, and the other end side is pressed with a finger while holding the weighted end with a finger, and TP-701-A heat seal tester (Tester Sangyo Co., Ltd.) The product was heat sealed at a temperature of 130 ° C., a pressure of 0.1 MPa, and a time of 0.5 seconds. As soon as the heat seal was completed, the weight was dropped, and the length of the part where the seal was peeled was measured. The measurement was performed 5 times and the average value was taken. Those having a peeled length of 100 mm or less were considered to have excellent hot tack properties.

Example 1
PP-1 (95% by weight) and PP-2 (5% by weight) are resins constituting the surface layer, and PP-3 (99.4% by weight) and an antifogging agent (0.6% by weight) are used. The resin constituting the base layer was PP-4 (90% by weight) and PE-1 (10% by weight) being the resins constituting the seal layer.
The resins constituting each of these layers were respectively charged into three extruders, and were co-extruded from a three-layer T die having a temperature of 230 ° C. so as to be laminated in the order of surface layer / base material layer / sealing layer, The raw sheet was obtained by cooling and solidifying with a cooling roll. Next, the sheet is heated to 130 ° C., roll-rolled 4.6 times in the MD direction, preheated at a set temperature 165 ° C. with a tenter, stretched 10 times in the TD direction at the set temperature 165 ° C., and then set temperature 165 After annealing at 0 ° C. and exiting the tenter, the corona discharge treatment was performed at 6.6 × 10 ² J / m ² on the surface layer side and 4.8 × 10 ² J / m ² on the seal layer side, The film of the present invention was obtained by winding with a winder. The total thickness of the obtained film of the present invention was 20 μm, and the thickness of each layer was surface layer / base material layer / sealing layer = 2 μm / 15 μm / 3 μm.
With respect to the obtained film of the present invention, haze value and hot tack property were evaluated. The evaluation results are shown in Table 1.

(Examples 2 to 4, Comparative Examples 1 and 2)
A film of the present invention or a comparative film was obtained in the same manner as in Example 1 except that the resin constituting each layer was changed as shown in Table 1. Each film obtained was evaluated for haze value and hot tack. The evaluation results are also shown in Table 1.

  As shown in Table 1, it is clear that the film of the present invention is a film excellent in sealing strength and hot tack property as compared with the film according to the comparative example.

Since the film of the present invention is particularly excellent in sealing strength and hot tackiness, it is possible to efficiently package fruits and vegetables etc., for example, with a vertical pillow packaging machine, and is useful as a biaxially oriented polypropylene film for packaging.

Claims (5)

A biaxially stretched polypropylene film having at least three layers of a surface layer, a base material layer, and a seal layer, wherein the seal layer contains 75 to 93% by weight of a propylene random copolymer and 7 to 25 polyethylene resin. The surface layer contains 50 to 99% by weight of a crystalline polypropylene resin having a melting point of 155 ° C. to 165 ° C. and 1 to 50% by weight of a crystalline polypropylene resin having a melting point of 166 ° C. to 175 ° C. A biaxially oriented polypropylene film characterized by the above. The biaxially oriented polypropylene according to claim 1 , wherein the crystalline polypropylene resin having a melting point of 166 ° C to 175 ° C has an isotactic pentad fraction (IP) of 97.0% or more by ¹³ C nuclear magnetic resonance spectrum. Film. The biaxially stretched polypropylene film according to claim 1 or 2 , wherein the base material layer contains an antifogging agent. The packaging bag manufactured using the biaxially stretched polypropylene-type film of any one of Claims 1-3 . The packaging bag according to claim 4 , which is for packaging fruits and vegetables.