JPH0531472B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Field of Industrial Application The present invention relates to a propylene resin film that has antifogging properties on both sides, and more specifically, a propylene resin film that has excellent antiblocking properties and heat sealability, and has excellent transparency, rigidity, and low-temperature impact properties. The present invention relates to a double-sided antifogging propylene resin film that is particularly suitable for packaging fresh meat, fresh fish, fruits and vegetables, etc. (b) Conventional technology Conventionally, antifogging propylene resin films intended to prevent water droplets from adhering to the inner surface of the film used in packaging fresh meat, fresh fish, fruits and vegetables, etc. have been produced using propylene homopolymer resins and propylene-ethylene random resins. A film prepared by adding an antifogging agent to a copolymer resin is used in a single layer or in a multilayer structure.
However, in these films, the antifogging agent bleeds out to the film surface within a short period of time, causing early loss of antifogging performance, causing blocking between the films, and whitening of the film due to changes over time. There is a problem that In addition, in order to suppress the short-term bleed-out of the antifogging agent, it has been considered to create a three-layer laminated film with an intermediate layer of resin containing an antifogging agent, but this method does not cause blocking between the films. In addition, in addition to imparting the normally required heat-sealability to the film surface, the ability to exhibit antifogging properties evenly on both surfaces is achieved by the migration of the antifogging agent to both surface layers. This is extremely difficult since it is highly dependent on differences in the resin composition of the layers. On the other hand, these antifogging films are required to have transparency, low-temperature impact resistance during low-temperature storage of packaged items, and rigidity during automatic packaging. However, it is not possible to achieve both rigidity and rigidity. (c) Problems to be Solved by the Invention The present invention has been made to solve the aforementioned problems in conventional antifogging propylene resin films, and has excellent anti-blocking properties and heat-sealing properties, and The purpose of the present invention is to provide a double-sided antifogging propylene resin film having transparency, rigidity, and low-temperature impact resistance. (d) Means for solving the problems The antifogging propylene resin film of the present invention includes:
In detail below, the antifogging agent with a melting point of 45 to 65℃ is 0.1 to
A three-layer laminated film consisting of an intermediate layer made of the following resin (A) added at 1.0% by weight, one surface layer made of the following resin (B), and the other surface layer made of the following resin (C). , characterized in that the surface of the surface layer made of the following resin (B) has been subjected to corona discharge treatment. (A) Propylene consisting of 60-95% by weight of a crystalline propylene polymer portion with an ethylene content of 2% by weight or less and 40-5% by weight of a propylene-ethylene copolymer portion with an ethylene content of 20-80% by weight. -Ethylene block copolymer resin. (B) A propylene-ethylene random copolymer resin or a propylene homopolymer resin having an ethylene content of less than 2% by weight. (C) Propylene-ethylene random copolymer resin with an ethylene content of 2 to 5% by weight, or propylene-ethylene-butene with an ethylene content of 0.5 to 3% by weight and a butene-1 content of 1 to 15% by weight. -1 Random copolymer resin. The resin (A) used for the intermediate layer in the present invention has an ethylene content of 2% by weight or less, preferably 1% by weight.
60 to 95% by weight of the following crystalline propylene polymer parts,
Preferably 70-85% by weight and ethylene content 20
It is a propylene-ethylene block copolymer resin comprising 40-5% by weight, preferably 30-15% by weight of a propylene-ethylene copolymer part of 80% by weight, preferably 30-70% by weight. When the ethylene content of the crystalline propylene polymer portion of this propylene-ethylene block copolymer resin exceeds 2% by weight, when the crystalline propylene polymer portion is less than 60% by weight, and when the propylene-ethylene copolymer resin contains If the ethylene content exceeds 80% by weight, the film will have insufficient rigidity. Furthermore, if the crystalline propylene polymer portion exceeds 95% by weight, or if the ethylene content of the propylene-ethylene copolymer portion is less than 20% by weight, the low-temperature impact properties of the film will be poor. Furthermore, if a resin other than this propylene-ethylene block copolymer resin is used as the intermediate layer, it will be difficult to control the migration of the antifogging agent added to the intermediate layer to both surface layers, resulting in Therefore, sufficient anti-fog performance cannot be provided. The antifogging agent added to the propylene-ethylene block copolymer resin has a melting point of 45 to 65°C, preferably 50 to 60°C. If the melting point is less than 45℃, the anti-blocking property as a laminated film,
The opening performance of the bag-made product will be poor, and 65
If the temperature exceeds .degree. C., the surface of the laminated film will whiten and the transparency will deteriorate. The antifogging agent can be selected from among, for example, fatty acid esters of polyhydric alcohols, ethylene oxide adducts of higher aliphatic amines, and higher fatty acid alkanolamides, which are generally called antifogging agents and antistatic agents. A mixture of glycerin monostearate and N,N-bis(2-hydroxyethyl)stearylamine is preferred. The amount of antifogging agent added is 0.1 to 1.0% by weight, preferably 0.2 to 0.6% by weight, based on the total amount of the antifogging agent and the propylene-ethylene block copolymer resin. If the amount added is less than 0.1% by weight, it will not be possible to impart antifogging properties to the laminated film, and if it exceeds 1.0% by weight, the anti-blocking properties of the laminated film and the opening properties of the bag-made product will be poor. Resin (B) used for one surface layer in the present invention
is a propylene-ethylene random copolymer resin or a propylene homopolymer resin having an ethylene content of less than 2% by weight. Among these, propylene-ethylene random copolymer resin having an ethylene content of 0.5 to 1.5% by weight is preferred. When the ethylene content of this propylene-ethylene random copolymer resin is 2% by weight or more,
Antifogging properties will not be imparted to the other surface layer of the laminated film, which will be described later. Further, the resin (C) used for the other surface layer in the present invention is a propylene-ethylene random copolymer resin having an ethylene content of 2 to 5% by weight, preferably 2.5 to 4% by weight, or
0.5-3% by weight, preferably 1-2% by weight, butene-1 content 1-15% by weight, preferably 4-9
% propylene-ethylene-butene-1 random copolymer resin. When the ethylene content of this propylene-ethylene random copolymer resin exceeds 5% by weight, and when the ethylene content of the propylene-ethylene-butene-1 random copolymer resin exceeds 3% by weight, and when the butene-1 random copolymer resin has an ethylene content of more than 3% by weight, If the content exceeds 15% by weight, the anti-blocking properties of the laminated film and the opening properties of its bag-made products will be significantly poor, and furthermore, the anti-fog properties of one of the surface layers will be poor. In addition, when the ethylene content of the propylene-ethylene random copolymer resin is less than 2% by weight, and when the propylene-ethylene-butene-1
When the ethylene content of the random copolymer resin is less than 0.5% by weight and when the butene-1 content is less than 1% by weight, the heat sheet properties as a laminated film are poor, and furthermore, this other surface layer has poor heat sheet properties. Anti-fog properties will not be provided. In addition, the resin (A), resin (B), and resin described above
The melt flow rate of (C) is preferably 1 to 30 g/10 minutes, particularly preferably 5 to 15 g/10 minutes. In the present invention, the three-layer laminate film of the above-mentioned intermediate layer and the above-mentioned one and the other surface layers is usually produced by a known coextrusion method, but
It can also be manufactured by extrusion lamination or a combination of both. In this three-layer laminated film, it is essential that the surface of the surface layer made of resin (B) is subjected to corona discharge treatment. The corona discharge treatment is carried out using a known corona discharge treatment apparatus such as a vacuum tube method or a thyristor method, so that the corona discharge treatment is approximately 35 to 42 dynes/cm, preferably approximately 36 to 40 dynes/cm. If the surface of the surface layer made of resin (B) is not subjected to corona discharge treatment, antifogging properties will not be imparted to this surface layer. The antifogging propylene resin film of the present invention is
The thickness of the intermediate layer is 10 to 50μ, preferably 15 to 45μ, and the thickness of one and the other surface layer is 2 to 50μ.
10μ, preferably 4-6μ. The thickness of the surface layer
If it is less than 2μ, the transparency as a laminated film will be poor;
If it exceeds 10μ, the antifogging properties and low-temperature impact properties intended by the present invention cannot be achieved. Note that each layer of the three-layer laminated film of the present invention may contain an antioxidant, an ultraviolet absorber, an anti-blocking agent, a lubricant, etc. In particular, an anti-blocking agent such as silicon dioxide, zeolite, calcium carbonate, etc. Preferably, it is added. However, lubricants such as oleic acid amide, stearic acid amide, and erucic acid amide, which are commonly used in polyolefin resins, impair the antifogging properties, so it is necessary to limit their addition to 0.04% by weight or less. (e) Action The antifogging propylene resin film of the present invention has the following properties:
Since the intermediate layer is composed of a specific propylene-ethylene block copolymer resin, it has rigidity and low-temperature impact resistance, and since both surface layers are composed of propylene-based resins with different compositions,
Furthermore, since a specific antifogging agent is added to the intermediate layer and the surface of one of the surface layers is corona discharge treated, both surfaces have an antifogging property. In addition, it can be made to have excellent properties such as anti-blocking properties and heat-sealing properties. Note that the antifogging propylene resin film of the present invention has one surface layer treated with corona discharge treatment, and heat sealing on this surface is difficult. Therefore, this film cannot be used to package items. In order to do this, it is necessary to form and package bags with the surface layer made of resin (B), whose surface has been subjected to corona discharge treatment, as the outside and the surface layer made of resin (C) as the object to be packaged. (F) Examples The physical properties in the Examples and Comparative Examples described below were measured by the following methods. Melting point of antifogging agent Measured according to JIS K0064, method 1 (transparent melting point method). Transparency The degree of haze was measured based on JIS K6714. Young's modulus Measured according to ISO R1184. Low-temperature impact strength A film was fixed in a ring shape in an atmosphere of 5°C, and the energy required when punching the film with a pendulum with a 1-inch impact head was measured. Anti-blocking property Two films were stacked so that the contact area was 10 cm ² and placed between two glass plates, and a load of 50 g/cm ² was applied and the film was left in an atmosphere of 40°C for 24 hours. The maximum load when peeling off was measured. Anti-fogging property A film was attached to a pot filled with water and left in an atmosphere at 5°C for 1 hour, and then the state of adhesion of water droplets on the inner surface of the film was observed and evaluated using the following evaluation scale. ◎; Transparent with no water droplets. ○: Water droplets adhere to some parts, but it is transparent. △: Quite a lot of water droplets adhered, making it translucent. ×; Water droplets adhere to the entire surface, making it opaque. Fused Seal Strength A bag was made with a fused seal with the non-corona discharge treated side facing inside, and the maximum load when the fused sealed portion was peeled off using a chopper type tester was measured. Example 1 Powder of the propylene-ethylene block copolymer resin PEB-1 shown in Table 1 was used as the resin (A), and 2,6-di-ethylene was added as an antioxidant to 100 parts by weight of the resin. 0.15 parts by weight of t-butyl-p-cresol, 0.05 parts by weight of calcium stearate as a neutralizing agent, and 0.5 parts by weight of the antifogging agent AF-1 shown in Table 3 were added, and the mixture was kneaded and pelletized. On the other hand, the propylene homopolymer resin PER-1 shown in Table 2 was used as the resin (B), the same antioxidant and neutralizing agent as in the resin (A) were added, and the mixture was kneaded and pelletized. In addition, the propylene-ethylene random copolymer resin PER-4 shown in Table 2 was used as the resin (C), the same antioxidants and neutralizing agents as in the resin (A) were added, and anti-blocking 0.2 parts by weight of silicon dioxide was added as an agent, and the mixture was kneaded and then pelletized. The three types of pellets obtained were supplied to three extruders, respectively, and melted and coextruded at 240°C using a three-layer T-die so that the resin (A) formed the intermediate layer. A three-layer laminated film was molded, with each layer having a thickness of 20 μm, one surface layer made of resin (B) having a thickness of 6 μm, and the other surface layer made of resin (C) having a thickness of 4 μm. Next, the surface of the surface layer made of resin (B) was subjected to a corona discharge treatment to give a discharge rate of 38 dynes/cm to produce an antifogging propylene resin film. After aging the obtained film at 35° C. for 3 days, transparency, Young's modulus, low-temperature impact strength, anti-blocking property, and anti-fogging property were evaluated. The results are shown in Table 4. Example 2 PEB-2, resin shown in Table-1 as resin (A)
An antifogging propylene resin film was prepared in the same manner as in Example 1, except that PER-2 shown in Table 2 was used as resin (B) and PER-5 shown in Table 2 was used as resin (C). It was manufactured and various physical properties including fusion seal strength were evaluated. Example 3 PEB-3 shown in Table 1 as resin (A), resin
An antifogging propylene resin film was prepared in the same manner as in Example 1, except that PER-3 shown in Table 2 was used as resin (B) and PER-7 shown in Table 2 was used as resin (C). It was manufactured and various physical properties were evaluated. Comparative Example 1 A film was produced in the same manner as in Example 1, except that PER-4 shown in Table 2 was used as the resin (B), and various physical properties were evaluated. Comparative Example 2 A film was produced in the same manner as in Example 1, except that PER-6 shown in Table 2 was used as the resin (C), and various physical properties were evaluated. Comparative Example 3 PER-2, resin shown in Table-2 as resin (B)
Films were produced in the same manner as in Example 1, except that PER-2 shown in Table 2 was used as (C), and various physical properties including fusing seal strength were evaluated. Comparative Example 4 A film was produced in the same manner as in Example 1, except that AF-2 shown in Table 3 was used as the antifogging agent.
Various physical properties were evaluated. Comparative Example 5 A film was produced in the same manner as in Example 1, except that the surface of the surface layer made of resin (B) was not subjected to corona discharge treatment, and its physical properties were evaluated.

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[Table] (G) Effects of the invention The antifogging propylene resin film of the present invention has
It is a double-sided antifogging film that has excellent anti-blocking and heat-sealing properties, as well as transparency, rigidity, and low-temperature impact resistance, and has great practical value as a packaging film for fresh meat, fresh fish, fruits and vegetables, etc.

Claims (1)

[Scope of Claims] 1. An intermediate layer made of the following resin (A) to which 0.1 to 1.0% by weight of an antifogging agent with a melting point of 45 to 65°C is added, and the following resin (B)
A three-layer laminated film consisting of one surface layer made of the following resin (C) and the other surface layer made of the following resin (B), characterized in that the surface of the surface layer made of the following resin (B) is corona discharge treated. Anti-fog propylene resin film. (A) Propylene consisting of 60-95% by weight of a crystalline propylene polymer portion with an ethylene content of 2% by weight or less and 40-5% by weight of a propylene-ethylene copolymer portion with an ethylene content of 20-80% by weight. -Ethylene block copolymer resin. (B) A propylene-ethylene random copolymer resin or a propylene homopolymer resin having an ethylene content of less than 2% by weight. (C) Propylene-ethylene random copolymer resin with an ethylene content of 2 to 5% by weight, or a propylene-ethylene random copolymer resin with an ethylene content of 0.5 to 3% by weight and a butene-1 content of 1 to 15% by weight
Butene-1 random copolymer resin.