WO2021241274A1

WO2021241274A1 - Biaxially oriented polypropylene resin film and package using same

Info

Publication number: WO2021241274A1
Application number: PCT/JP2021/018398
Authority: WO
Inventors: 和也桐山; 徹今井; 理木下
Original assignee: 東洋紡株式会社
Priority date: 2020-05-29
Filing date: 2021-05-14
Publication date: 2021-12-02
Also published as: JPWO2021241274A1; TW202204158A

Abstract

[Problem]　To provide a biaxially oriented polypropylene resin film characterized in being suitable for automatic packaging methods, capable of satisfying both a post-automatic packaging heat seal strength and a fusion sealing method heat seal strength, and having superior anti-fogging properties, anti-dripping properties, slipperiness, and blocking resistance. [Solution]　A biaxially oriented polypropylene resin film, according to the present invention, having a base layer (A) comprising a resin composition that includes polypropylene resin and polyethylene resin, a seal layer (B), on one surface of said base layer (A), comprising a polypropylene resin composition mainly composed of a propylene/butene-1 copolymer, and a surface layer (C) on the base layer (A) on the reverse side from the seal layer (B), and fulfills the following conditions a-d. a) The melt flow rate at 190℃ of the polyethylene resin constituting the base layer (A) is from 1.5 g/10 minutes to 10 g/10 minutes, inclusive, the density thereof is from 0.910 g/cm³ to 0.930 g/cm³, inclusive, and 1 wt% to 20 wt% thereof is included with respect to 100 wt% total of the polypropylene resin and polyethylene resin constituting the base layer (A). b) The thickness of the seal layer (B) is 1 μｍ or less. c) 0.1 wt% to 1.0 wt%, inclusive, of an anti-fogging agent is included in the polypropylene composition constituting the seal layer (B). d) The surface roughness SRa (arithmetic average roughness) of the surface layer (C) is 0.018 μｍ or more.

Description

Biaxially oriented polypropylene resin film and packaging using it

The present invention relates to a biaxially oriented polypropylene-based resin film and a package using the same, and is particularly composed of plants such as vegetables, fruits, and flowers that are required to have high freshness because they have a heat-sealing property and an antifogging effect. The present invention relates to a biaxially oriented polypropylene-based resin film suitable for packaging fresh products (hereinafter referred to as fruits and vegetables in the present specification) and a package using the same.

Conventionally, biaxially oriented polypropylene-based resin films have been widely used in the packaging field such as food packaging and fiber packaging because they are excellent in optical properties, mechanical properties, packaging suitability, and the like.
In particular, anti-fog films are widely used for packaging fruits and vegetables such as vegetables.

Especially in fruit and vegetable packaging, labor saving in agricultural work is required due to the recent decline in the agricultural population, and the automatic packaging method is becoming widespread. The so-called pillow packaging method is adopted as the automatic packaging method for fruits and vegetables, and the bag making process by heat sealing and the filling process of the contents can be performed at the same time.

Applicable to the automatic packaging method, the outer layer made of a biaxially stretched film containing a crystalline polypropylene resin as a main component has a propylene-ethylene-butene co-weight having a melting point 10 to 90 ° C lower than the melting point of the outer layer. A laminated film obtained by melt-extruding and laminating a coalescence is disclosed (see, for example, Patent Document 1).

Suitable for the automatic packaging method and excellent in heat seal strength, it is a polyolefin-based layer using a polypropylene-based resin-based base layer and a propylene-butene-1 copolymer and a propylene-ethylene-butene-1 copolymer. A packaging film composed of two or more layers having a heat-sealing layer mainly composed of a resin is disclosed (see, for example, Patent Document 2).

Further, a packaging film that can be used for both automatic packaging such as pillow packaging and fusing seal packaging is disclosed (see, for example, Patent Document 3).
However, even in these conventional heat-sealable polypropylene-based laminated films, further improvement in anti-fog property, particularly drip-proof property, slipperiness, and blocking resistance has been required.

A biaxially stretched polypyrene film having a heat-sealing property, which contains polyethylene derived from a plant, is also disclosed (see, for example, Patent Document 4).

Japanese Patent No. 3104166 Japanese Patent No. 4385443 JP-A-2019-166830 JP-A-2019-6461

The present invention has been made against the background of the problems of the prior art. That is, an object of the present invention is suitable for an automatic packaging method, is satisfactory in both heat-sealing strength after automatic packaging and heat-sealing strength in a fusing sealing method, and is more excellent in drip-proofness, slipperiness, and blocking resistance. It is an object of the present invention to provide a biaxially oriented polypropylene-based resin film.

As a result of diligent studies in view of the above problems, the present invention has the characteristics of the polypropylene-based resin and the polyethylene-based resin constituting the base material layer (A), their respective ratios, and the seal layer (B) and the surface layer (C). Due to the specific range of the characteristics of the above and the characteristics of the seal layer (B) and the surface layer (C), it is particularly excellent in drip-proof, slippery and blocking resistance, and also has fusing sealability and heat sealability. , A polypropylene-based laminated film could be obtained.
That is, the present invention has the following configuration.

1. 1. A polypropylene-based resin composition mainly composed of a propylene / butene-1 copolymer on one surface of a base material layer (A) made of a resin composition containing a polypropylene-based resin and a polyethylene-based resin and the base material layer (A). A biaxial structure in which the seal layer (B) made of an object has a surface layer (C) on the surface of the base material layer (A) opposite to the seal layer (B) and satisfies the following conditions a) to d). Oriented polypropylene resin film.
a) The melt flow rate of the polyethylene resin constituting the base material layer (A) is 1.5 g / 10 minutes or more and 10 g / 10 minutes or less at 190 ° C., and the density is 0.910 g / cm ³ or more and 0.930 g /. It is cm ³ or less, and is contained in an amount of 1% by weight or more and 20% by weight based on 100% by weight of the total of the polypropylene-based resin and the polyethylene-based resin constituting the base material layer (A).
b) The thickness of the seal layer (B) is 1 μm or less.
c) The polypropylene-based composition constituting the seal layer (B) contains 0.1% by weight or more and 1.0% by weight or less of the antifog agent.
d) The surface roughness SRa (arithmetic mean roughness) of the surface layer (C) is 0.018 μm or more.

2. 2. 1. The melting point of the propylene / butene-1 copolymer or the plurality of propylene / butene-1 copolymers is in the range of 120 to 130 ° C. The biaxially oriented polypropylene-based resin film described in 1.

3. 3. 1. The content of the propylene / butene-1 copolymer or the plurality of propylene / butene-1 copolymers is in the range of 50% by weight or more. Or 2. The biaxially oriented polypropylene-based resin film described in 1.

4. 1. The thickness of the seal layer (B) is 1.5% or more and 4% or less with respect to the entire film layer. ~ 3. Biaxially oriented polypropylene-based resin film according to any one of.

5. The base material layer (A) is an isotactic propylene homopolymer, a propylene / ethylene copolymer, a propylene / butene-1 copolymer, a propylene / ethylene / butene-1 copolymer, or a propylene / penten copolymer. 1. Consists of a polypropylene-based resin composition mainly composed of at least one polypropylene-based resin selected from the group consisting of coalescing. ~ 4. Biaxially oriented polypropylene-based resin film according to any one of.

6. The surface layer (C) is at least one polypropylene-based resin selected from the group consisting of a propylene / ethylene / butene-1 copolymer, a propylene / butene-1 copolymer, and a propylene / ethylene copolymer. 1. Consists of a resin composition as a main component. ~ 5. Biaxially oriented polypropylene-based resin film according to any one of.

7. 1. The melting point of the polypropylene-based resin constituting the surface layer (C) is in the range of 130 to 140 ° C. ~ 6. Biaxially oriented polypropylene-based resin film according to any one of.

8. 1. The thickness of the surface layer (C) is 1.5% or more and 4% or less with respect to the entire film layer. ~ 7. Biaxially oriented polypropylene-based resin film according to any one of.

9. 1. The heat seal strength when the seal layers (B) of the biaxially oriented polypropylene resin film are heat-sealed at 120 ° C. is 3.5 N / 15 mm or more. -8. The polypropylene-based laminated film according to any one of.

10. 1. The blocking value measured by combining the seal layer (B) and the surface layer (C) of the biaxially oriented polypropylene resin film is 110 mN / 200 mm or less. ~ 9. The polypropylene-based laminated film according to any one of.

11. 1. The coefficient of friction between the surface layers (C) of the biaxially oriented polypropylene-based resin film is 0.35 or less. ~ 10. The polypropylene-based laminated film according to any one of.

12.1. ~ 11. A package using the biaxially oriented polypropylene-based resin film according to any one of.

The biaxially oriented polypropylene-based resin film of the present invention has excellent slipperiness and blocking resistance, is satisfactory in both heat-sealing strength after automatic packaging and heat-sealing strength in the fusing sealing method, and becomes cloudy due to water droplets after vegetable packaging. It is suitable for keeping the freshness of vegetables because it is less.

The biaxially oriented polypropylene-based resin film of the present invention has a base material layer (A) made of a resin composition containing a polypropylene-based resin and a polyethylene-based resin, and propylene / butene on one surface of the base material layer (A). 1 The seal layer (B) made of a resin composition mainly composed of a copolymer has a surface layer (C) on a surface of the base material layer (A) opposite to the seal layer (B).

(Base material layer (A))
[Polypropylene resin]
In the present invention, the resin composition constituting the base material layer (A) contains a polypropylene-based resin.
The polypropylene-based resin is at least one selected from the group consisting of an n-heptane-insoluble isotactic propylene homopolymer and a copolymer of propylene containing 70 mol% or more of propylene and another α-olefin. It is preferably made of the resin of.
The n-heptane insoluble index indicates the crystallinity of polypropylene and at the same time indicates the safety when used for food packaging. In the present invention, n-heptane insoluble according to the February 1982 Ministry of Health and Welfare Notification No. 20. It is a preferable embodiment to use the one having an elution amount of 150 ppm or less when extracted at 25 ° C. for 60 minutes [30 ppm or less when the operating temperature exceeds 100 ° C.]).

When an isotactic propylene homopolymer and a copolymer of propylene containing 70 mol% or more of propylene and another α-olefin are mixed and used, the resin used for the base material layer (A) is used. It is desirable that the content of the copolymer of propylene containing 70 mol% or more of propylene and other α-olefins is 50% by weight or more with respect to the entire composition. It is more preferably 70% by weight or more, still more preferably 90% by weight or more.

Examples of the α-olefin copolymer component of the copolymer of propylene and other α-olefins include α-olefins having 2 to 8 carbon atoms, such as ethylene, butene-1, pentene-1, hexene-1, and 4. -Methyl-1-pentene and the like are preferable. Here, the copolymer is preferably a random or block copolymer obtained by polymerizing one or more of the α-olefins exemplified above with propylene, and is preferably a propylene / ethylene copolymer. It is preferably a propylene / butene-1 copolymer, a propylene / ethylene / butene-1 copolymer, or a propylene / penten copolymer.
The ratio of the α-olefin monomer-derived component to the total of the propylene monomer-derived component and the α-olefin monomer-derived component of the polypropylene-based resin used in the base material layer (A) is 0. It is preferably 3 mol% or more. By doing so, both rigidity and fusing sealability can be achieved at a high level. It is more preferably 0.4 mol% or more, and further preferably 0.5 mol% or more.
The melting point of the polypropylene-based resin used for the base material layer (A) is preferably 156 ° C. or higher. The melting point is measured by the method described in Examples described later. When the melting point is 156 ° C. or higher, it is easy to smoothly transport the film in the automatic packaging process, and the obtained bag-making product is less likely to wrinkle.
The ratio of the α-olefin monomer-derived component to the total of the propylene monomer-derived component and the α-olefin monomer-derived component of the polypropylene-based resin used in the base material layer (A) is 1.0 mol% or less from the viewpoint of the melting point. Is preferable. By doing so, it is easy to obtain a fusing seal property. It is more preferably 0.9 mol% or less, and further preferably 0.8 mol% or more.
Further, the melt flow rate (MFR) can be exemplified in the range of 0.1 to 100 g / 10 min, preferably 0.5 to 20 g / 10 min, and more preferably 1.0 to 10 g / 10 min.

[Polyethylene resin]
In the present invention, the resin composition constituting the base material layer (A) contains a polyethylene-based resin. The polyethylene-based resin is a resin containing ethylene as a main component, and for example, any ethylene homopolymer such as high-pressure method low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene can be used. Other than possible, α-olefins such as propylene, butene-1, penten-1, hexene-1,3-methylbutene-1, 4-methylpentene-1, octene-1, vinyl acetate, (meth) acrylic acid, ( Meta) Crystalline with a monomer such as acrylic acid ester, low crystalline to non-crystalline random or block copolymer, or a mixture thereof can be used.

The polyethylene-based resin is preferably contained in an amount of 1% by weight or more and 20% by weight based on 100% by weight of the total of the polypropylene-based resin and the polyethylene-based resin constituting the base material layer (A). When it is 1% by weight or more, the heat seal strength, slipperiness and blocking resistance, and drip-proof property are improved. It is more preferably 5% by weight or more, still more preferably 8% by weight. When it is 20% by weight or less, it is easy to maintain the rigidity. It is more preferably 18% by weight or less, still more preferably 15% by weight or less.

The melting point of the polyethylene resin is preferably in the range of 100 ° C. or higher and 135 ° C. or lower, more preferably 105 ° C. or higher and 130 ° C. or lower, from the viewpoint of heat resistance, transparency, mechanical properties and film forming property. As for the density, measured in accordance with JIS K7112, preferably from 0.90 g / cm ³ or more 0.94 g / cm ³ or less, 0.91 g / cm ³ or more 0.94 g / cm ³ or less is more preferable.

As for the density, measured in accordance with JIS K7112, preferably from 0.90 g / cm ³ or more 0.94 g / cm ³ or less, 0.91 g / cm ³ or more 0.94 g / cm ³ or less is more preferable.
The melt flow rate (MFR) of the polyethylene resin measured under the conditions of 190 ° C. and 2.16 kg load according to ASTM D1238 is preferably 0.5 g / 10 minutes or more, more preferably 1 g / 10 minutes or more. It is more preferably 2 g / 10 minutes or more, preferably 20 g / 10 minutes or less, more preferably 15 g / 10 minutes or less, still more preferably 10 g / 10 minutes or less from the viewpoint of further stabilizing the moldability.

As the polyethylene resin, it is preferable to use a polyethylene resin made from plant-derived ethylene as a raw material. The biobase degree of the polyethylene resin measured in accordance with ISO16620 is preferably 50% or more and 100% or less, preferably 70% or more and 100% or less, and 80% or more and 100% or less. Is more preferable.

According to the study of the present inventor, when the polypropylene-based resin composition constituting the base material layer (A) contains a polypropylene-based resin and a specific polyethylene-based resin, it is formed on the surfaces of the seal layer (B) and the surface layer (C). Since fine surface irregularities are formed, improvement in slipperiness and blocking resistance can be seen.
Further, the melting point of the polyethylene-based resin is low, and the melting point of the polypropylene-based resin is high, so that the heat seal reaching strength is high. For example, if a polyethylene resin having a melting point of around 120 ° C. is used, the heat-sealing reach strength when heat-sealed at 120 ° C. is increased.
Further, when the polypropylene-based resin composition constituting the base material layer (A) contains a polypropylene-based resin and a specific polyethylene-based resin, it becomes more cloudy even when the amount of water droplets adhering to the film surface is small in a low temperature environment. I found it difficult.
The reason for this is that the crystallinity of the polypropylene-based resin composition constituting the base material layer (A) is lowered, and the transfer (bleed-out) of the anti-fog agent to the seal layer (B) and the surface layer (C) is further promoted. And it is possible that it will last longer.

[Anti-fog agent]
It is preferable that the resin composition constituting the base material layer (A) contains an anti-fog agent. By including the anti-fog agent in the resin composition constituting the base material layer (A), the anti-fog agent of the base material layer (A) is sequentially transferred to the seal layer (B) and the surface layer (C), and the film is formed. The anti-fog property of the surface is easy to maintain.
Typical examples of the antifogging agent include fatty acid esters of polyhydric alcohols, amines of higher fatty acids, amides of higher fatty acids, amines of higher fatty acids and ethylene oxide adducts of amides. Can be done.
The abundance of the antifogging agent in the base material layer (A) is preferably 0.1 to 1.0% by weight, and is 0.2 to 0.8% by weight in terms of all layers. Is more preferred, more preferably 0.3 to 0.8% by weight, and particularly preferably 0.4 to 0.8% by weight.

[Thickness of base material layer (A)]
The thickness of the base material layer (A) is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 50 μm or less, and further preferably 15 μm or more and 25 μm or less.

(Seal layer (B))
[Polypropylene resin]
The polypropylene-based resin composition constituting the seal layer (B) is mainly composed of a propylene / butene-1 copolymer. Since the propylene / butene-1 copolymer is mainly used, the sealing layer (B) is easily mixed with each other, so that the interface is less likely to be formed and the heat seal reaching strength can be exhibited.
Further, the propylene / butene-1 copolymer has a small amount of copolymerization components, and peeling at the interface with the base material layer (A) is unlikely to occur. Therefore, even if the thickness of the seal layer (B) is reduced, sufficient heat seal reaching strength can be obtained.
As the propylene / butene-1 copolymer, a plurality of propylene / butene-1 copolymers can be used, but a single type of propylene / butene-1 copolymer is preferable.
The melting point temperature of these propylene / butene-1 copolymers is preferably in the range of 120 to 130 ° C. When the melting point is 130 ° C. or lower, the heat seal rising temperature does not easily rise too high even if the anti-fog agent is contained, and when the melting point is 120 ° C. or higher, the heat seal rising temperature does not easily rise too low.
The content of the propylene / butene-1 copolymer in the polypropylene-based resin composition constituting the seal layer is preferably 90% by weight or more in order to improve the heat seal ultimate strength or more, and is 95% by weight or more. It is more preferable to have.

From the viewpoint of heat seal reachability, a polypropylene resin composition mainly composed of a propylene / butene-1 copolymer is used for the seal layer. However, in order to raise the heat seal rise temperature to 115 to 125 ° C. It is important that the antifogging agent is added to 0.3% by weight or more in the seal layer (B) so that the heat seal rise temperature does not become too low. If the amount of anti-fog agent is less than 0.3% by weight, the heat seal rise temperature decreases. It is preferably 0.3 to 0.8% by weight, more preferably 0.45 to 0.7% by weight.
At this time, when the fruits and vegetables are packaged and displayed or distributed at a supermarket or the like, it is possible to prevent the inside from becoming cloudy due to the physiological action of the contents.

[Anti-fog agent]
The polypropylene-based resin composition constituting the seal layer (B) contains an anti-fog agent. The effect can be exhibited when fruits and vegetables, which are characterized by maintaining their physiological action even after harvesting, are targeted for packaging.
By adding the anti-fog agent only to the base material layer (A) during the production of the biaxially oriented polypropylene-based resin film of the present invention, the anti-fog agent can be used as a sealing layer during the production of the film and the storage after the film is formed. The film sequentially shifts (bleeds out) to (B), and the film surface becomes anti-fog. An anti-fog agent may be added to all of the base layer (A), the seal layer (B), and the surface layer (C) during the production of the film.

In order to maintain excellent anti-fog properties over the long term in the distribution process, it is desirable that the package be stored in a room temperature atmosphere rather than frozen storage, so considering the temperature changes during storage and distribution. It is preferable to select an anti-fog agent that continuously exhibits anti-fog properties during the course of repeated temperature changes between 5 and 30 ° C.
Typical examples of the antifogging agent include fatty acid esters of polyhydric alcohols, amines of higher fatty acids, amides of higher fatty acids, amines of higher fatty acids and ethylene oxide adducts of amides. Can be done.
The abundance of the antifogging agent in the seal layer (B) is preferably 0.1 to 1.0% by weight, and may be 0.2 to 0.8% by weight in terms of all layers. More preferably, it is more preferably 0.3 to 0.8% by weight, and particularly preferably 0.4 to 0.8% by weight.

[Additive]
Further, as long as the effect of the present invention is not impaired, various additives for improving quality such as slipperiness and antistatic property, for example, lubricants such as wax and metal soap for improving productivity, and plasticizers. It is also possible to add known heat stabilizers, antioxidants, antistatic agents, ultraviolet absorbers and the like which are usually added to agents, processing aids and polypropylene films.
Further, it is preferable to add inorganic or organic fine particles for ensuring the blocking resistance and slipperiness of the film.

Examples of the inorganic fine particles include silicon dioxide, calcium carbonate, titanium dioxide, talc, kaolin, mica, and zeolite, and these shapes are not limited to spherical, elliptical, conical, and amorphous. As for the particle size, a desired particle size can be used and blended depending on the intended use and usage of the film.
Further, as the organic fine particles, crosslinked particles such as acrylic, methyl acrylate, and styrene-butagee can be used, and various particles such as inorganic fine particles can be used in terms of shape and size. It is possible.
Further, it is possible to apply various surface treatments to the surface of these inorganic or organic fine particles, and these can be used alone or in combination of two or more.

The average particle size of the inorganic or organic fine particles is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more. The average particle size is preferably 5 μm or less, more preferably 4 μm or less.
The average particle size of the fine particles was measured as follows.
Particles are dispersed in ion-exchanged water stirred at a predetermined rotation speed (about 5000 rpm) using a high-speed stirrer, the dispersion is added to isoton (physiological saline), further dispersed by an ultrasonic disperser, and then called. The particle size distribution was obtained by the counter method and calculated as the average particle size.
The content of the fine particles is preferably 0.3% by weight or more, more preferably 0.5% by weight or more, and 0.7% by weight, based on the polypropylene-based resin composition constituting the seal layer (B). % Or more is further preferable, 1.0% by weight or more is further preferable, 3.0% by weight or less is preferable, 2.0% by weight or less is more preferable, and 1.7% by weight or less is further preferable.

[Thickness of seal layer (B)]
The presence of the seal layer (B) and the surface layer (C) promotes the migration (bleed-out) of the anti-fog agent to the film surface, and the thicker the film, the greater the effect on the drip-proof property, but the seal. The thickness of the layer (B) needs to be 1 μm or less. If it exceeds 1 μm, the fusing seal strength when the bag is made by the fusing sealing method becomes insufficient, and fine surface irregularities are formed on the surface of the sealing layer (B), so that slipperiness and blocking resistance are improved. Can be seen.
Further, the thickness of the seal layer (B) is preferably 1.5% or more with respect to the entire film layer in terms of heat seal strength after automatic packaging, and 4% or less is preferable in terms of fusing seal strength. ..
The strength of the fusing seal is greatly affected by the size of the fused resin portion called the poly pool at the time of fusing sealing. The thickness of the seal layer (B) is preferably 0.1 μm or more.
The seal layer (B) needs to be provided on only one surface of the base material layer (A), and if it is provided on both sides of the base material layer (A), the film adheres to the seal bar in the automatic packaging process and the packaging is defective. Is likely to occur.

(Surface layer (C))
[Polypropylene resin]
The surface layer (C) is mainly composed of at least one polypropylene-based resin selected from the group consisting of a propylene / ethylene / butene-1 copolymer, a propylene / butene-1 copolymer, and a propylene / ethylene copolymer. Can be. When one of these resins is used, it is easy for the seal layers to mix with each other, it is easy for the interface to be difficult to form, and it is easy to develop the heat seal ultimate strength.
The melting point temperature of the polypropylene-based resin is preferably in the range of 130 to 140 ° C. When the melting point is 140 ° C. or lower, the heat seal rises and the temperature does not rise too high even if the anti-fog agent is contained, and when the melting point is 130 ° C. or higher, the heat seal rises and the temperature does not rise too low.
At least one selected from the group consisting of a propylene / ethylene / butene-1 copolymer, a propylene / butene-1 copolymer, and a propylene / ethylene copolymer in the polypropylene-based resin composition constituting the surface layer (C). The content of one type of polypropylene-based resin is preferably 90% by weight or more, which is preferable for improving the heat seal reaching strength, and more preferably 95% by weight or more.

The heat seal rising temperature of the surface layer (C) is preferably 130 ° C. or higher and 140 ° C. or lower. The heat seal rising temperature of the surface layer (C) is the heat when the surfaces of the surface layer (C) of the film of the present invention face each other, the heat seal pressure is 1 kg / cm ² , and the time is 1 second. This is the temperature at which the seal strength is 1 N / 15 mm. When the heat seal rise temperature of the surface layer (C) is 130 ° C. or higher, the surface layer (C) is difficult to fuse with the seal bar during heat sealing of pillow packaging, and it is easy to make a bag. Further, when the temperature is 140 ° C. or lower, the back-pasted portion easily fuses with the exterior portion of the package during pillow packaging and has a good appearance, and the back-pasted portion does not get caught when the packages are stacked, so that the seal does not peel off.

[Anti-fog agent]
The surface of the surface layer (C) preferably has anti-fog properties. When packaging fruits and vegetables and displaying them at supermarkets, the appearance will improve if the surface becomes cloudy due to condensation.
Typical examples of the antifogging agent include fatty acid esters of polyhydric alcohols, amines of higher fatty acids, amides of higher fatty acids, amines of higher fatty acids and ethylene oxide adducts of amides. Can be done.
The abundance of the antifogging agent in the surface layer (C) is preferably 0.1 to 1.0% by weight, and may be 0.2 to 0.8% by weight in terms of all layers. More preferably, it is more preferably 0.3 to 0.8% by weight, and particularly preferably 0.4 to 0.8% by weight.

Examples of the inorganic fine particles include silicon dioxide, calcium carbonate, titanium dioxide, talc, kaolin, mica, and zeolite, and these shapes are not limited to spherical, elliptical, conical, and amorphous. As for the particle size, a desired particle size can be used and blended depending on the intended use and usage of the film.
Further, as the organic fine particles, crosslinked particles such as acrylic, methyl acrylate, and styrene-butadiene can be used, and various particles such as inorganic fine particles can be used in terms of shape and size. It is possible.
Further, it is possible to apply various surface treatments to the surface of these inorganic or organic fine particles, and these can be used alone or in combination of two or more.

The average particle size of the inorganic or organic fine particles is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more. The average particle size is preferably 5 μm or less, more preferably 4 μm or less.
The average particle size of the fine particles was measured as follows.
Particles are dispersed in ion-exchanged water stirred at a predetermined rotation speed (about 5000 rpm) using a high-speed stirrer, the dispersion is added to isoton (physiological saline), further dispersed by an ultrasonic disperser, and then called. The particle size distribution was obtained by the counter method and calculated as the average particle size.
The content of the fine particles is preferably 0.3% by weight or more, more preferably 0.5% by weight or more, and 0.7% by weight, based on the polypropylene-based resin composition constituting the surface layer (C). % Or more is further preferable, 1.0% by weight or more is further preferable, 3.0% by weight or less is preferable, 2.0% by weight or less is more preferable, and 1.7% by weight or less is further preferable.

(Thickness of surface layer (C))
When the polypropylene-based resin composition constituting the base material layer (A) contains a polypropylene-based resin and a specific polyethylene-based resin, fine surface irregularities are formed on the surface of the surface layer (C), so that the surface layer (C) The smaller the thickness, the larger the size of the surface unevenness, but the anti-fog property is less likely to be exhibited, so that the surface layer (C) is indispensable. However, if the thickness of the surface layer (C) is too large, the size of the surface unevenness becomes small, so it is also necessary to control the thickness.
The thickness of the surface layer (C) is preferably 1 μm or less. When it is 1 μm or less, the fusing seal strength is easily obtained, and fine surface irregularities are formed on the surface of the surface layer (C), so that slipperiness and blocking resistance are improved.
Further, the thickness of the surface layer (C) is 1.5% or more with respect to the entire film layer in terms of the heat seal strength after automatic packaging, and the bag is made by the fusing seal method when the thickness is 4% or less. It is preferable in terms of the strength of the fusing seal. The thickness of the surface layer (C) is preferably 0.1 μm or more.

(Film thickness)
The film thickness of the biaxially oriented polypropylene-based resin film of the present invention varies depending on its use and usage, but the polypropylene-based film as a packaging film is generally about 10 to 100 μm, and has mechanical strength and transparency. It is more preferably about 15 to 50 μm, further preferably about 15 to 40 μm, and particularly preferably about 15 to 25 μm.

(Method for forming a biaxially oriented polypropylene resin film)
The biaxially oriented polypropylene-based resin film of the present invention is not different from the film-forming conditions in the case of general polyolefin, for example, by a T-die method or an inflation method using an extruder suitable for the number of layers. Examples thereof include a method of melt-laminating and then cooling by a cooling roll method, a water cooling method or an air cooling method to form a laminated film, which is then stretched by a sequential biaxial stretching method, a simultaneous biaxial stretching method, a tube stretching method or the like.
Here, exemplifying the conditions for manufacturing by the sequential biaxial stretching method, a resin melt-extruded from a T-shaped die is cooled and solidified by a casting machine to prepare a raw sheet. At this time, the roll temperature for melt casting is preferably set between 15 ° C. and 40 ° C. for the purpose of suppressing crystallization of the resin and improving transparency.
Next, after heating the raw sheet to a temperature suitable for stretching, the sheet is stretched in the flow direction of the sheet by utilizing the speed difference between the stretching rolls. At this time, the stretching ratio at this time is stable and stable. Considering what to do, it is preferable to set it between 3 times and 6 times. Next, both ears of the vertically stretched sheet are grasped by a tenter clip, and the sheet is stretched while being sequentially expanded in a direction perpendicular to the flow of the sheet while being heated to a temperature suitable for stretching with hot air. The lateral stretching ratio at this time is preferably set between 7 times and 10 times in consideration of thickness variation and productivity.

The biaxially oriented polypropylene-based resin film of the present invention can be surface-treated in order to improve printability, laminateability, and the like. Examples of the surface treatment method include corona discharge treatment, plasma treatment, flame treatment, acid treatment, and the like, and are not particularly limited. It is preferable to perform corona discharge treatment, plasma treatment, and flame treatment, which can be continuously treated and can be easily carried out before the winding step of the film manufacturing process.

(Film characteristics)
The biaxially oriented polypropylene-based resin film of the present invention preferably has the following characteristics.

(Heat seal rise temperature)
In the present invention, the heat seal rising temperature of the seal layer (B) is preferably 115 ° C. or higher and 125 ° C. or lower. The heat seal rising temperature of the seal layer (B) is the heat when the surfaces of the seal layer (B) of the film of the present invention face each other, the heat seal pressure is 1 kg / cm ² , and the time is 1 second. This is the temperature at which the seal strength is 1 N / 15 mm.

When the heat seal rise temperature of the seal layer (B) is 125 ° C. or lower, sufficient strength is maintained even if the heat seal temperature is low, and heat seal is easy, and it is easy to operate at high speed during automatic packaging. In addition, the sealing portion is excellent in sealing property, so that the freshness of the fresh product is maintained in combination with the antifogging property, the contents look good, and the package is easy to handle.
When the heat seal rise temperature of the seal layer (B) is 125 ° C. or lower, the difference in melting point from the base material layer (A) mainly composed of polypropylene resin becomes large, and the seal bar is automatically heated without increasing the temperature. Since it is easy to increase the operating speed of the package sufficiently and the set temperature does not have to be raised in order to increase the heat seal strength, the entire laminated film is less likely to shrink during heat seal, the heat seal part is less likely to wrinkle, and the heat seal part is less likely to occur. It is unlikely to cause poor sealing. When the heat seal rise temperature of the seal layer (B) is less than 115 ° C., the strength of the fusing seal when the bag is made by the fusing sealing method decreases, and it becomes difficult to use both the automatic packaging method and the fusing sealing method.

(Strength reached by heat seal at 120 ° C)
In order to prevent the contents of the biaxially oriented polypropylene-based resin film of the present invention from falling off, the heat seal reaching strength in the longitudinal direction and the lateral direction at 120 ° C. obtained by the measurement method described later is 3.5 N. / 15 mm or more is preferable. The longitudinal direction here means the direction in which the film flows from the casting of the raw material resin composition to the step of winding the stretched film, and the lateral direction means the direction perpendicular to the flow direction. The same applies to the following far characteristics.

(Anti-fog)
The biaxially oriented polypropylene-based resin film of the present invention preferably has an anti-fog property of rank 3 or higher obtained by the measurement method described later. It is more preferably rank 2 or higher, and even more preferably rank 1.

(Anti-fog unevenness)
The biaxially oriented polypropylene-based resin film of the present invention preferably has an anti-fog unevenness evaluation of rank 2 or lower obtained by the measurement method described later. More preferably, it is rank 1.

(Drip-proof)
The biaxially oriented polypropylene-based resin film of the present invention preferably has a drip-proof property of rank 3 or lower obtained by the measurement method described later. It is more preferably rank 2 or lower, and even more preferably rank 1.

(Aptitude for automatic packaging)
The biaxially oriented polypropylene-based resin film of the present invention preferably has an automatic packaging suitability evaluation of 〇 or Δ obtained by the measurement method described later. More preferably, it is 〇.

(Fusing seal strength)
The biaxially oriented polypropylene-based resin film of the present invention preferably has a fusing seal strength of 25 N / 15 mm or more obtained by the measurement method described later. It is more preferably 28 N / 15 mm or more, and further preferably 29 N / 15 mm or more.

(120 ° C. heat shrinkage rate)
The biaxially oriented polypropylene-based resin film of the present invention preferably has a heat shrinkage rate of 3.7% or less in the vertical direction at 120 ° C. obtained by the measurement method described later. It is more preferably 3.5% or less, further preferably 3.0% or less, and particularly preferably 2.5% or less.
It is preferable that the heat shrinkage rate at 120 ° C. obtained by the measurement method described later is 3.5% or less in the width direction. It is more preferably 3.0% or less, further preferably 2.0% or less, still more preferably 1.6% or less, and particularly preferably 1.3% or less.

(Haze)
The biaxially oriented polypropylene-based resin film of the present invention preferably has a haze of 8% or less obtained by the measurement method described later. It is more preferably 7% or less, further preferably 6% or less, still more preferably 5% or less.

(Dynamic friction coefficient)
The biaxially oriented polypropylene-based resin film of the present invention preferably has a dynamic friction coefficient of 0.38 or less in both the longitudinal direction and the width direction obtained by the measurement method described later. It is more preferably 0.35 or less, further preferably 0.32 or less, even more preferably 0.30 or less, and particularly preferably 0.28 or less.

(Blocking resistance)
In the biaxially oriented polypropylene-based resin film of the present invention, the blocking value obtained by the measurement method described later is preferably 110 mN / 200 mm or less, more preferably 100 mN / 200 mm or less.

(Surface roughness SRa)
The biaxially oriented polypropylene-based resin film of the present invention preferably has a surface roughness SRa of 0.018 μm or more, more preferably 0019 μm or more, obtained by the measurement method described later.

Hereinafter, specific examples of the present invention will be further described with reference to Examples, but the present invention is not limited to the following Examples as long as the gist of the present invention is not deviated. The characteristics in the present specification were evaluated by the following method.

(1) Layer Thickness A biaxially oriented polypropylene-based resin film was cut into a size of 1 cm × 1 cm, embedded in a UV curable resin, and irradiated with UV for 5 minutes to solidify. Then, a cross-sectional sample was prepared by a microtome, observed with a differential interference microscope, and the thicknesses of the entire film layer, the seal layer (B), and the surface layer (C) were measured. The sample was measured at 5 points and the average value was calculated.

(2) Heat-seal rise temperature The seal layers (B) of the biaxially oriented polypropylene-based resin film are stacked facing each other, and a heat-seal pressure tester (manufactured by Toyo Seiki Co., Ltd.) is used to heat-seal pressure 1 kg / cm ² , time. Is the temperature at which the heat seal strength becomes 1 N / 15 mm when heat-sealed at a temperature increased by 5 ° C from 80 ° C in 1 second, and the heat-seal layer surfaces of the 5 cm × 20 cm film face each other at 5 ° C. Heat seal with 5 heat seal bars (seal surface 1 cm x 3 cm) whose temperature is set at the pitch at the same time, cut the center part to a width of 15 mm, attach it to the upper and lower chucks of the tensile tester, and at a tensile speed of 200 mm / min. The respective strengths when pulled were measured, and the heat seal strength was calculated (unit: N / 15 mm). A linear graph was drawn with the temperature on the horizontal axis and the heat seal strength on the vertical axis, and the temperature at which the heat seal strength exceeded 1 N / 15 mm was defined as the heat seal rise temperature.

(3) 120 ° C. Heat Seal Strength The seal layers (B) of the biaxially oriented polypropylene resin film are stacked facing each other, and a heat seal pressure tester (manufactured by Toyo Seiki Co., Ltd.) is used to heat seal pressure 1 kg / cm ² . The time was 1 second, heat-sealed at 120 ° C., the central part was cut to a width of 15 mm, attached to the upper and lower chucks of a tensile tester, and calculated from the heat-sealed strength when pulled at a tensile speed of 200 mm / min ( The unit is N / 15 mm).

(4) Anti-fog property 1) Put 300 cc of hot water at 50 ° C in a 500 cc upper opening container.
2) Anti-fog property of the film Seal the container opening with the film with the measurement surface inside.
3) Leave it in a cold room at 5 ° C.
4) With the hot water in the container completely cooled to the atmospheric temperature, the dew adhesion state on the film surface was evaluated on a 5-point scale.
・ Evaluation 1st grade: No dew on the entire surface (adhesion area 0)
・ Evaluation 2nd grade: Some dew adhesion (up to 1/4 of the adhesion area)
・ Evaluation grade 3: Dew adhesion of about 1/2 (up to 2/4 of the adhesion area)
・ Evaluation 4th grade: Almost dew adhered (up to 3/4 of the adhered area)
・ Evaluation 5th grade: Dew adhered to the entire surface (adhesion area 3/4 or more)

(5) Anti-fog unevenness 1) Put 300 cc of hot water at 50 ° C in a 500 cc upper opening container.
2) Anti-fog property of the film Seal the container opening with the film with the measurement surface inside.
3) Leave at 20 ° C for 20 seconds.
4) The state of dew adhesion on the film surface was evaluated on a 5-point scale.
・ Evaluation 1st grade: No dew on the entire surface (adhesion area 0)
・ Evaluation 2nd grade: Some dew adhesion (up to 1/4 of the adhesion area)
・ Evaluation grade 3: Dew adhesion of about 1/2 (up to 2/4 of the adhesion area)
・ Evaluation 4th grade: Almost dew adhered (up to 3/4 of the adhered area)
・ Evaluation 5th grade: Dew adhered to the entire surface (adhesion area 3/4 or more)

(6) Drip-proof 1) Put 300 cc of warm water at 30 ° C in a 500 cc upper opening container.
2) Anti-fog property of the film Seal the container opening with the film with the measurement surface inside.
3) Leave it in a cold room at 5 ° C.
4) With the hot water in the container completely cooled to the atmospheric temperature, the dew adhesion state on the film surface was evaluated on a 5-point scale.
・ Evaluation 1st grade: No dew on the entire surface (adhesion area 0)
・ Evaluation 2nd grade: Some dew adhesion (up to 1/4 of the adhesion area)
・ Evaluation grade 3: Dew adhesion of about 1/2 (up to 2/4 of the adhesion area)
・ Evaluation 4th grade: Almost dew adhered (up to 3/4 of the adhered area)
・ Evaluation 5th grade: Dew adhered to the entire surface (adhesion area 3/4 or more)
Since the evaluation of the drip-proof property uses hot water at 30 ° C., the amount of water droplets adhering to the film surface is smaller than that when hot water at 50 ° C. is used, which makes a stricter evaluation judgment.

(7) Suitability for automatic packaging Heat-seal layers of biaxially oriented polypropylene-based resin films are stacked facing each other, and a heat-seal tester (manufactured by Toyo Seiki Co., Ltd.) is used to heat-seal pressure 1 kg / cm ² , time 1 second. Heat-sealed with.
At that time, the presence or absence of fusion of the surface layer (C) to the seal bar and the heat seal rise temperature were evaluated according to the following criteria.
◯: No fusion to the seal bar ・ Rise temperature 115 ℃ or more and 125 ℃ or less △: No fusion to the seal bar ・ Rise temperature less than 115 ℃ or higher than 125 ℃ ×: Fusion to the seal bar

(8) Fusing Seal Strength A fusing seal bag of a biaxially oriented polypropylene-based resin film was prepared using a fusing sealing machine (manufactured by Kyoei Printing Machinery Co., Ltd .: PP500 type).
Condition: Fusing blade; Cutting edge angle 60 °
Seal temperature; 370 ° C
Number of shots; 120 bags / minute The fusing seal part of the above fusing seal bag is cut to a width of 15 mm, and both ends are gripped by the gripping part of the tensile tester (grasping interval: 200 mm) with the looseness removed, and the tensile speed is 200 mm. Tensile at / min, the fusing seal strength (N / 15 mm) was calculated from the strength when the seal portion was broken. The number of measurements was 5 times and averaged. It was judged that the fusing seal suitability was good at 20 N / 15 mm or more.

(9) Heat shrinkage rate Measured by the following method in accordance with JIS Z1712. The biaxially oriented polypropylene resin film was cut into a width of 20 mm and a length of 200 mm in each of the MD direction and the TD direction, hung in a hot air oven at 120 ° C., and heated for 5 minutes. The length after heating was measured, and the heat shrinkage rate was determined by the ratio of the contracted length to the original length.

(10) Haze Measured according to JIS K7105.

(11) Dynamic friction coefficient The surface layer (C) surfaces of two biaxially oriented polypropylene-based resin films were overlapped with each other, and measured at 23 ° C. in accordance with JIS K7125. Five sets of samples were measured and the average value was calculated.

(12) Blocking value A biaxially oriented polypropylene-based resin film is cut out by 150 mm in the longitudinal direction and 200 mm in the lateral direction, and the seal layer (B) and the surface layer (C) are put together and sandwiched between the top and bottom, and a 20 kg weight is placed in the center. And put it in an oven at 60 ° C. It was taken out after 24 hours, seasoned at a temperature of 23 ° C. and a humidity of 65% for 1 hour, and a 6.35Φ test rod was fixed to the bonded portion.
With a tensile tester (5965 dual column desktop tester manufactured by Instron), the film and the fixing jig are gripped at a grip distance of 200 mm, pulled at a tensile speed of 100 mm / min, and the strength when the films are peeled off is blocked. The value was set to (mN / 200 mm). Three samples were measured and the average value was calculated.

(12) Surface roughness SRa
The surface roughness of the obtained biaxially oriented polypropylene resin film was evaluated using a three-dimensional roughness meter (manufactured by Kosaka Research Institute, model number ET-30HK) at a stylus pressure of 20 mg and a measurement length in the X direction. The arithmetic average roughness described in JISB 0601 (1994) was measured with a feed speed of 1 mm, a feed speed of 100 μm / sec, a feed pitch of 2 μm in the Y direction, 99 recording lines, a magnification of 20000 times in the height direction, and a cutoff of 80 μm. Calculated according to the definition of. Surface roughness SRa was tried three times each and evaluated by the average value.

(Example 1)
(1) Resin used The polypropylene-based resin, polyethylene-based resin, and additives used as raw materials constituting each layer used in the following production examples are as follows.
(1) Base material layer (A)
[PP-1]: Propylene / ethylene random copolymer: "FS2011DG3" manufactured by Sumitomo Chemical Co., Ltd., ethylene content: 0.6 mol%, MFR: 2.7 g / 10 minutes, melting point: 158 ° C., mesopentad Fraction: 97.0%
[Anti-fog agent-1]: Glycerin monostearate (Matsumoto Oil & Fat Pharmaceutical Co., Ltd., TB-123) [Anti-fog agent-2]: Polyoxyethylene (2) Stearylamine (Matsumoto Oil & Fat Pharmaceutical Co., Ltd., TB- 12)
[Anti-fog agent-3]: Polyoxyethylene (2) Stearylamine monostearate (Matsumoto Yushi Pharmaceutical Co., Ltd., Elex 334)
[PE-1]: Ethylene homopolymer: "SLH218" manufactured by Braskem, MFR: 2.3 g / 10 minutes, melting point: 126 ° C., biobase degree: 84%

(2) Seal layer (B)
[PP-2]: Propylene-butene-1 copolymer: "SPX78J1" manufactured by Sumitomo Chemical Industries, Ltd., butene content: 25 mol%, MFR: 8.5 g / 10 minutes, melting point: 128 ° C.
[Anti-fog agent-1]: Glycerin monostearate (Matsumoto Yushi Pharmaceutical Co., Ltd., TB-123)

(4) Surface layer (C) Resin composition [PP-3]: Propylene / ethylene / butene random copolymer: "FSX66E8" manufactured by Sumitomo Chemical Industry Co., Ltd., ethylene content: 2.5 mol%, butene content : 7 mol%, MFR: 3.1 g / 10 minutes, melting point: 133 ° C.
[Anti-fogant-1]: Glycerin monostearate (Matsumoto Yushi Pharmaceutical Co., Ltd., TB-123) [Organic polymer fine particles]: Crosslinked acrylic particles: CS30: Sumitomo Chemical Industry Co., Ltd., Particle size: 3.5 μm

The raw materials used in each of the base material layer (A), the seal layer (B), and the surface layer (C) were mixed at the ratios shown in Table 1. Using three melt extruders, the mixed raw material of the base material layer (A) is melt-extruded from the first extruder at a resin temperature of 280 ° C., and the mixed raw material of the surface layer (C) is melt-extruded by the second extruder. Melt-extruded at a resin temperature of 250 ° C., melt-extruded the mixed raw material of the seal layer (B) from a third extruder at a resin temperature of 250 ° C., and the surface layer (C) / substrate layer from the chill roll contact surface. In the order of (A) / seal layer (B), the thickness ratio in the T-die is the surface layer (C) / base layer layer (A) / seal layer (B) = 0.6 / 18.7 / 0. It was laminated and extruded to 7 and then cooled and solidified with a cooling roll at 30 ° C. to obtain an unstretched sheet. Subsequently, the metal rolls heated to 130 ° C. were stretched 4.5 times in the vertical direction by utilizing the difference in peripheral speed, further introduced into a tenter stretching machine, and stretched 9.5 times in the horizontal direction. .. The temperature of the preheated portion of the tenter stretching machine was 168 ° C., the temperature of the stretched portion was 155 ° C., and then heat fixing was performed at 163 ° C.

The surface of the surface layer (C) is subjected to corona discharge treatment by a corona discharge processor manufactured by Kasuga Electric Co., Ltd., and then the seal layer (B) is similarly subjected to corona discharge treatment, which can be wound up by a film winder and automatically packaged. A biaxially oriented polypropylene-based resin film was obtained. The final film thickness was 20 μm, and the thickness ratio of the seal layer (B) to the entire film was 3.5%.
The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing and sealing, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Example 2)
A laminated film was obtained in the same manner as in Example 1 except that the content of [PE-1] in the base material layer (A) was 10% by weight. The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing and sealing, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the content of [PE-1] in the base material layer (A) was 20% by weight. The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing and sealing, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Example 4)
A laminated film was obtained in the same manner as in Example 1 except that [PP-2] was 80% by weight and [PP-3] was 20% by weight as the mixed raw material of the seal layer (B). The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing and sealing, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Example 5)
A laminated film was obtained in the same manner as in Example 1 except that the thickness of the base material layer (A) was 38.7 μm, the film thickness was 40 μm, and the thickness ratio of the seal layer (B) was 1.8%. The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing and sealing, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Example 6)
A laminated film was obtained in the same manner as in Example 2 except that the thickness of the base material layer (A) was increased to 38.7 μm, the film thickness was 40 μm, and the thickness ratio of the seal layer (B) was 1.8%. .. The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing seals, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Example 7)
A laminated film was obtained in the same manner as in Example 3 except that the thickness of the base material layer (A) was 38.7 μm, the film thickness was 40 μm, and the thickness ratio of the seal layer (B) was 1.8%. The obtained multilayer film satisfies the requirements of the present invention, and the suitability for automatic packaging, the suitability for fusing and sealing, the anti-fog property, and the drip-proof property are at a level where there is no problem in fruit and vegetable packaging. The film composition and physical characteristics are shown in Table 1.

(Comparative Example 1)
A laminated film was obtained in the same manner as in Example 1 except that the amount of [PE-1] added to the base material layer (A) was 0% by weight. The obtained laminated film has deteriorated drip-proof property, slipperiness, and blocking resistance. The film composition and physical characteristics are shown in Table 1.

(Comparative Example 2)
A laminated film was obtained in the same manner as in Example 5 except that the amount of [PE-1] added to the base material layer (A) was 0% by weight. Similarly, the obtained laminated film also deteriorates in drip-proofness, slipperiness, and blocking resistance. The film composition and physical characteristics are shown in Table 1.

(Comparative Example 3)
A laminated film was obtained in the same manner as in Example 1 except that the thickness of the base material layer (A) was 19.3 μm and the thickness of the surface layer (C) was 0.0 μm. The obtained laminated film has significantly deteriorated anti-fog property. The film composition and physical characteristics are shown in Table 1.

(Comparative Example 4)
A laminated film was obtained in the same manner as in Example 1 except that the thickness of the base layer (A) was 18.1 μm and the thickness of the surface layer (C) was 1.2 μm. The obtained laminated film has deteriorated fusing seal strength, slipperiness, and blocking resistance. The film composition and physical characteristics are shown in Table 1.

(Comparative Example 5)
A laminated film was obtained in the same manner as in Example 5 except that the thickness of the base material layer (A) was 39.3 μm and the thickness of the surface layer (C) was 0.0 μm. The obtained laminated film has significantly deteriorated anti-fog property. The film composition and physical characteristics are shown in Table 1.

(Comparative Example 6)
A laminated film was obtained in the same manner as in Example 5 except that the thickness of the base layer (A) was 38.1 μm and the thickness of the surface layer (C) was 1.2 μm. The obtained laminated film has deteriorated fusing seal strength, slipperiness, and blocking resistance. The film composition and physical characteristics are shown in Table 1.

The self-packaging biaxially oriented polypropylene-based resin film of the present invention is a film having excellent antifogging and drip-proof properties, excellent slipperiness and blocking resistance, and high heat seal reaching strength at 120 ° C. Suitable for packaging, especially for vegetable packaging.

Claims

A polypropylene-based resin composition mainly composed of a propylene / butene-1 copolymer on one surface of a base material layer (A) made of a resin composition containing a polypropylene-based resin and a polyethylene-based resin and the base material layer (A). A biaxial structure in which the seal layer (B) made of an object has a surface layer (C) on the surface of the base material layer (A) opposite to the seal layer (B) and satisfies the following conditions a) to d). Oriented polypropylene resin film.
a) The melt flow rate of the polyethylene resin constituting the base material layer (A) is 1.5 g / 10 minutes or more and 10 g / 10 minutes or less at 190 ° C., and the density is 0.910 g / cm 3 or more and 0.930 g /. It is cm 3 or less, and is contained in an amount of 1% by weight or more and 20% by weight based on 100% by weight of the total of the polypropylene-based resin and the polyethylene-based resin constituting the base material layer (A).
b) The thickness of the seal layer (B) is 1 μm or less.
c) The polypropylene-based composition constituting the seal layer (B) contains 0.1% by weight or more and 1.0% by weight or less of the antifog agent.
d) The surface roughness SRa (arithmetic mean roughness) of the surface layer (C) is 0.018 μm or more.
The biaxially oriented polypropylene-based resin film according to claim 1, wherein the propylene / butene-1 copolymer has a melting point in the range of 120 to 130 ° C.
The biaxially oriented polypropylene-based resin film according to claim 1 or 2, wherein the content of the propylene / butene-1 copolymer is in the range of 50% by weight or more.
The biaxially oriented polypropylene-based resin film according to any one of claims 1 to 3, wherein the thickness of the seal layer (B) is 1.5% or more and 4% or less with respect to the entire film layer.
The base material layer (A) is an isotactic propylene homopolymer, a propylene / ethylene copolymer, a propylene / butene-1 copolymer, a propylene / ethylene / butene-1 copolymer, or a propylene / penten copolymer. The biaxially oriented polypropylene-based resin film according to any one of claims 1 to 4, which comprises a resin composition mainly composed of at least one polypropylene-based resin selected from the group consisting of coalesced compounds.
The surface layer (C) is at least one polypropylene-based resin selected from the group consisting of a propylene / ethylene / butene-1 copolymer, a propylene / butene-1 copolymer, and a propylene / ethylene copolymer. The biaxially oriented polypropylene-based resin film according to any one of claims 1 to 5, which comprises a resin composition as a main component.
The biaxially oriented polypropylene-based resin film according to any one of claims 1 to 6, wherein the polypropylene-based resin constituting the surface layer (C) has a melting point in the range of 130 to 140 ° C.
The biaxially oriented polypropylene-based resin film according to any one of claims 1 to 7, wherein the thickness of the surface layer (C) is 1.5% or more and 4% or less with respect to the entire film layer.
The polypropylene according to any one of claims 1 to 8, wherein the heat-sealing strength when the sealing layers (B) of the biaxially oriented polypropylene-based resin film are heat-sealed at 120 ° C. is 3.5 N / 15 mm or more. System laminated film.
The polypropylene-based product according to any one of claims 1 to 9, wherein the blocking value measured by combining the seal layer (B) and the surface layer (C) of the biaxially oriented polypropylene-based resin film is 110 mN / 200 mm or less. Laminated film.
The polypropylene-based laminated film according to any one of claims 1 to 10, wherein the surface layer (C) of the biaxially oriented polypropylene-based resin film has a friction coefficient of 0.35 or less.
A package using the biaxially oriented polypropylene resin film according to any one of claims 1 to 11.