JP2000255676A - Cheese wrapping film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve easiness in separating from a cheese and to reduce cost for wrapping for a film for individual wrapping of sliced cheese by a method wherein average roughness at the surface of an internal layer contacting with the cheese is specified for a plastic film composed at least of two or more laminates. SOLUTION: What required for an internal layer contacting with a cheese of a cheese wrapping film are easy separability from the cheese, exclusiveness against impurities, and heat-sealability with a face not contacting with the cheese, and in order to materialize the easy separability from the cheese among the above-mentioned requirements, 10-point average roughness at the surface of an internal layer contacting with the cheese is set within a range of 1.0-10 μm. The internal layer contacting with the cheese contains at least one or more resins selected out of low density polyethylene, an ethylene-vinyl acetate copolymer, an ethylene-methyl acrylate copolymer and the like, and sealing strength between the internal layer and an external layer not contacting with the cheese after wrapping of the cheese is set within a range of 5-600 g/15 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a film for individually packaging thin cheese.

[0002]

2. Description of the Related Art A thin cheese is usually formed into a cylindrical film by means of a center seal, a melted cheese is poured into the inner surface of the film, the thickness is adjusted by a gap between rolls, and the film is cooled in a water tank.
It is manufactured by sealing and cutting the front and rear, and the speed is 500 sheets / min to 1000 sheets / min. Finally, about 10 sheets are collectively packaged and marketed as a product.

[0003] Hitherto, many thin cheese packaging films have been proposed. For example, polyester or polypropylene films coated with cellophane, a resin such as a polyvinylidene chloride resin or a polyamide resin mixture, and a coextruded polypropylene film having a polypropylene heat seal layer.

[0004] In these thin cheese packaging materials, the inner surface is required to be easily peelable from the cheese and to seal foreign substances, and the outer surface is required to have water repellency. Further, the portion where the film overlaps on the cheese needs to be bonded by a center seal.

[0005]

However, the conventional packaging material does not have heat sealing property on the inner surface of the polyester film as disclosed in Japanese Patent Application Laid-Open No. 1-175354. It was easily damaged or aerobic mold was formed. Also, Japanese Patent Application Laid-Open No. 10-1011
Even with a heat seal layer as in No. 74, the same phenomenon is likely to occur because the sealability of contaminants is poor and it is practically difficult to seal.

[0006] Further, those disclosed in JP-A-9-40012 and JP-A-10-128924, in which a polyvinylidene chloride resin is coated on polyester or polypropylene to provide heat sealing properties, have poor peelability from cheese. In addition, there have been cases where continuous use has become difficult from the viewpoint of recent environmental effects.

Further, as disclosed in Japanese Patent Application Laid-Open No. 10-750, a resin obtained by extrusion laminating a resin containing linear low-density polyethylene polymerized using a metallocene catalyst on the surface of polyester or polypropylene in order to provide heat sealing properties is disclosed. Even if the cost is higher and the performance is better than the conventional product, it has not been easy to accept.

[0008] In addition, a polyester film coated with a polyvinylidene chloride resin to which a wax component or the like is added on the inner surface is widely used, but the adhesion between the polyester surface and the polyvinylidene chloride surface during center sealing is not sufficient. However, there was a serious disadvantage that the cheese leaked out due to peeling during packaging.

In the present invention, in order to solve these problems, the inner surface is rich in the sealing of impurities and is excellent in easy peeling from cheese, and the outer surface has water repellency and is environmentally friendly. In addition, the present invention provides an ideal film for cheese packaging that leads to a reduction in packaging material costs and that can be heat-sealed on the inner surface and the outer surface.

[0010]

Means for Solving the Problems The present invention provides the following items 1 to
5

(Claim 1) In a plastic film composed of at least two layers, the 10-point average roughness (Rz) of the surface of the inner surface layer (A) in contact with the cheese is 1.0 μm.
A film for packaging cheese, having a thickness of 10 μm or less.

(Item 2) The cheese packaging film according to item 1, wherein the inner surface layer (A) in contact with the cheese is a layer containing at least 50 mol% of a monomer unit based on ethylene.

(Claim 3) Inner surface layer in contact with cheese (A)
But low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-methacrylic acid copolymer (EMAA), ethylene-acrylic acid copolymer Merging (E
AA), ethylene-ethyl acrylate copolymer (EE
A) containing at least one resin selected from A), and having a seal strength of 5 to 600 g / 15 mm after packaging the cheese between the layer (A) and the outer surface layer (B) not in contact with the cheese. Item 3. The cheese packaging film according to Item 1 or 2, wherein

(Item 4) Outer surface layer not in contact with cheese (B)
Is a layer containing 70% of polypropylene or polyester, The film for cheese packaging according to any one of Items 1 to 3, wherein

(Item 5) Outer surface layer not in contact with cheese (B)
Contains 70% of polypropylene or polyester,
Item 5. The film for packaging cheese according to any one of Items 1 to 4, which is a stretched layer.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details will be described below.

What is required for the inner layer (A) of the film for cheese packaging that comes into contact with the cheese is "easy peeling off from the cheese", "sealing of contaminants" and "heat sealing of the surface not in contact with the cheese". It is.

In the present invention, in order to realize "easy peeling from cheese", the surface of the inner surface layer (A) in contact with the cheese is roughened so that the melted cheese flows into the inner layer (A). Instead of making the cheese completely adhere to the film, the film did not allow the cheese to penetrate into the fine concave portions. This made it possible to impart easy peelability from the cheese.

The surface roughness is not necessarily specified because it is related to the appearance of the film, but preferably the 10-point average roughness (Rz) is 1.0 μm to 10 μm.
m, more preferably 1.2 μm to 8 μm, even more preferably 1.5 μm to 5 μm.

This has a 10-point average roughness (Rz) of 1.0 μm.
If less than 10 m, the peelability from cheese is poor.
When the amount exceeds the limit, it is difficult to obtain the sealing property of the contaminants via the cheese, which easily leads to drying of the cheese and generation of mold.

As for the surface roughening method, a method of physically roughening the surface with a roughening roll nip device or the like, a method of mixing two or more resins having poor compatibility, for example, ethylene-
A method of mixing a vinyl acetate copolymer (EVA) and polypropylene may be mentioned, but there is no particular limitation on the method of roughening as long as expected surface roughness can be obtained.

An additive may be added in order to enhance the releasability from the innermost layer of cheese. For example, fatty acid amides such as erucic acid amide, stearic acid amide, oleic acid amide, and behenic acid amide, and other higher fatty acid amides, higher fatty acids, derivatives thereof, and waxes can be exemplified, but the type is not particularly limited.

As to the amount of addition, when added in a large amount, bleed-out may deteriorate the performance or impair the heat sealing property. Therefore, 0.05 to 2.0% by weight, preferably 0.05% by weight. To 1.0% by weight, but there is no particular limitation.

Regarding the “contaminant sealing property”, the resin constituting the inner surface layer (A) which comes into contact with the cheese is made of a resin containing a monomer based on ethylene, so that the softness of the resin itself causes the contaminant sealing property. , And sufficient sealing is possible even if the cheese is sandwiched at the time of sealing. The resin containing a monomer based on ethylene includes low-density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), and ethylene-methacrylic acid copolymer. Merging (E
MAA), ethylene-acrylic acid copolymer (EAA),
In addition to ethylene-ethyl acrylate copolymer (EEA), ethylene-butene copolymer, ionomer, linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), ultra low density Polyethylene (VLDPE) and the like. Even when any of the above resins is used, even when a plurality of resins are mixed, it is necessary that the monomer unit based on ethylene in the inner surface layer (A) in contact with the cheese is 50 mol% or more. is there.

Regarding the "heat sealability", the resin containing the monomer based on ethylene described above is contained in the inner surface layer (A) which comes into contact with the cheese. Sufficient sealing strength can be obtained for individual packaging of cheese.

The seal strength is preferably 5
g / 15 mm to 600 g / 15 mm, more preferably 2
It is 0 g / 15 mm to 500 g / 15 mm, more preferably 50 g / 15 mm to 300 g / 15 mm.

This is because if the thickness is 5 g / 15 mm or less, the seal may be peeled off when the film is cut in a packaging machine during cheese packaging, and 600 g / 1.
If the thickness is 5 mm or more, the cheese is likely to be deformed or broken because the strength is too strong at the time of opening, and it cannot be said that the sealing strength is appropriate.

As long as the water repellency is not hindered, it is also possible to provide an inner surface layer (A) in contact with the cheese on both sides of the outer layer (B) not in contact with the cheese.

The outer layer (B) which does not come into contact with the cheese is required to have water repellency (good drainage). Amides, higher fatty acids and their derivatives, waxes and the like can be added.

As for the amount of addition, if a large amount is added, the performance may decrease due to bleed-out.
5% by weight to 2.0% by weight, preferably 0.05% by weight to
1.0% by weight can be exemplified, but there is no particular limitation.

As for the water repellency, the contact angle with distilled water in the outer surface layer (B) not in contact with the cheese is 70 ° or more, preferably 80 ° or more, more preferably 90 ° from the viewpoint of drainage.

The surface of the outer layer (B) which does not come into contact with the cheese may be subjected to a surface treatment because a product name, a company name, a company mark or the like may be printed on the surface. Examples of the surface treatment include corona treatment, flame treatment, and plasma treatment.
The treatment may be performed in the air or in an inert gas, but it is necessary that the treatment be performed within a range that does not impair the water repellency (the contact angle with distilled water is within the above-described range).

An overcoat layer may be provided for the purpose of protection of printing. However, when the film is completely covered, the contact angle of distilled water on the surface of the overcoat is within the above-mentioned range, and the inner surface layer in contact with the cheese is provided. It is preferable to design so that the heat seal strength with (A) becomes appropriate.

The outer layer (B) not in contact with the cheese is preferably a layer containing 70% or more of polypropylene or polyester. More preferably, it is a stretched layer containing 70% or more of polypropylene or polyester.

[0035] This is because when the resin is not contained, the necessary rigidity and heat resistance may not be obtained at the time of packaging.

The stretching method is not particularly limited, but a uniaxial stretching method,
Examples include a sequential biaxial stretching method and a simultaneous biaxial stretching method.

The stretching ratio is preferably from 1.2 to 1.2 in the machine direction.
It is about 5 times and about 5 to 10 times in the horizontal direction. The stretching temperature is about 80 to 140 ° C. in the longitudinal direction, preferably 70 to 140 ° C.
~ 100 ° C, 100 ~ 180 ° in horizontal direction
C, preferably about 130 to 170 ° C.

If necessary, an interlayer adhesive layer may be provided between the inner layer (A) in contact with the cheese and the outer layer (B) not in contact with the cheese. There is no particular limitation on the resin used for the interlayer adhesive layer.
E), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), dense density polyethylene (MDPE), very low density polyethylene (VLDPE),
Ethylene-vinyl acetate copolymer (EVA), saponified EVA, ethylene-methyl acrylate copolymer (EM
A), ethylene-methacrylic acid copolymer (EMA)
A), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-butene copolymer, ethylene-propylene copolymer, propylene-butene, propylene-ethylene-butene terpolymer , Ionomers, and resins containing maleic anhydride modified products thereof, or mixtures thereof.

The thickness of the film is not particularly limited, but the thickness of the inner layer (A) in contact with the cheese is from 1 μm to
5 μm, 1 for outer layer (B) not in contact with cheese
0 μm to 35 μm, total thickness 15 μm to 40
It can be said that a thickness of about μm is substantially appropriate.

[0040]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. In addition, the measuring method and evaluation method in an Example and a comparative example are as follows.

(10 points average roughness (Rz)) Surfcom 5
Using 75A-3D (manufactured by Tokyo Seimitsu Kikai), the surface roughness of the inner layer (A) in contact with the cheese was measured.

(Releasability) Processed cheese 1 melted by heating
0 g was applied on a film having an area of 50 cm ² , and after cooling and solidifying in a refrigerator for 24 hours, the cheese and the film were peeled off, and the amount of cheese remaining on the film surface was evaluated.

(Contamination of impurities) 10 g of the heated and melted process cheese is sandwiched between two films of 10 cm × 10 cm and rolled so that the thickness of the cheese becomes 2 mm, and a heat sealer (manufactured by Toyo Seiki Seisaku-sho, Ltd.) is produced. Using, temperature 13
Heat sealing was performed at 0 ° C., and the sealability of the foreign matter between the inner surface layers (A) in contact with the cheese was evaluated from the state of the sealed portion.

(Seal strength) The inner layer (A) that comes into contact with the cheese of the film and the outer layer (B) that does not come into contact with the cheese are each 15 mm × 10 m at 2 kg, 0.5 seconds and 145 ° C.
The film was heat-sealed to a width of m, and both ends of the film were pulled in a direction of 180 degrees at a pulling speed of 200 mm / min, and the average sealing strength (20 N) was obtained.

Example 1 A laminated film having a two-layer structure was manufactured using the following raw materials. (1) Raw material ・ Inner layer (A) in contact with cheese = vinyl acetate content 1
5% by weight of EVA (80% by weight) and polypropylene (20% by weight)-Outer layer (B) not in contact with cheese = polypropylene (2) Manufacturing method The components (A / B) of each layer are cooled with a T-die from a T-die. Was co-extruded on a chill roll circulated to obtain a flat two-layer film. Thereafter, the film was longitudinally stretched 5 times by a roll stretching machine at 110 ° C, and further transversely stretched 10 times by a tenter stretching machine in an atmosphere at 150 ° C. The thickness of the obtained film for cheese packaging is A / B = 5/25 (μ
m). Table 1 shows the physical property values of the obtained cheese packaging film.

(Example 2) Except that the following raw materials were used,
A cheese packaging film having a thickness of A / B = 5/25 (μm) was produced in the same manner as in Example 1. Table 1 shows the physical property values of the obtained cheese packaging film. -Inner layer (A) in contact with cheese = EMA (80% by weight) and polypropylene (20% by weight) with methyl acrylate content of 15% by weight-Outer layer (B) = polypropylene not in contact with cheese

Example 3 The components (A / C /
B) was co-extruded from a T-die onto a chill roll in which cooling water was circulated to obtain a flat three-layer film.
Thereafter, the film was longitudinally stretched 5 times by a roll stretching machine at 110 ° C, and further transversely stretched 10 times by a tenter stretching machine in an atmosphere at 150 ° C. Next, the surface of the inner surface layer (A) in contact with the cheese was roughened using a roughening roll nip device having a surface roughness of 100 mesh. A / C / B = 5/3/22 (μ)
m). Table 1 shows the physical property values of the obtained cheese packaging film.・ Inner layer (A) in contact with cheese = vinyl acetate content 1
5% by weight of EVA ・ Interlayer adhesive layer (C) = maleic anhydride modified product of linear low density polyethylene ・ Outer surface layer not in contact with cheese (B) = polyethylene terephthalate

(Comparative Example 1) Except using the following raw materials,
A / B = 5/25 (μm) thickness in the same manner as in Example 1.
Thus, a laminated film having a two-layer structure having only a single layer was produced. Obtained
Table 1 shows the physical properties of the obtained film.・ Inner layer (A) in contact with cheese = vinyl acetate content 1
5% by weight of EVA-outer layer not in contact with cheese (B) = polypropylene The physical properties of the obtained film are shown in Table 1.

(Comparative Example 2) Except for using the following raw materials,
In the same manner as in Example 1, a two-layer laminated film having a thickness of A / B = 5/25 (μm) was produced. Table 1 shows the physical property values of the obtained film. -Inner layer (A) in contact with cheese = propylene content 8
0% by weight of propylene-butene copolymer-Outer layer not in contact with cheese (B) = polypropylene The physical properties of the obtained film are shown in Table 1.

[0050]

[Table 1]

The film for cheese packaging obtained in Examples 1 to 3 was excellent in all of the releasability, sealing property for impurities, and sealing strength, and was suitable for cheese packaging. on the other hand,
When the film obtained in Comparative Example 1 was used, the peelability was poor and it was unsuitable for cheese packaging. In addition, the film obtained in Comparative Example 2 had problems in the releasability, the sealing property of contaminants, and the sealing strength, and was not suitable for practical use.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kenichi Furuya 2-4-12 Nakazaki Nishi, Kita-ku, Osaka-shi, Osaka Gunze Co., Ltd. Plastics Division F-term (reference) 3E035 AA18 BA08 BA10 BC02 BD10 CA07 4F100 AK01A AK01B AK04A AK06A AK07B AK25A AK41B AK68A AK70A AL01A BA02 BA31 DD07A EJ37B GB23 JB06 JK06 JL11 JL14 YY00 YY00A

Claims (5)

[Claims] 1. A plastic film comprising at least two layers, wherein the surface of the inner surface layer (A) in contact with the cheese has a 10-point average roughness (Rz) of 1.0 μm or more and 10 μm or less. Film for cheese packaging. 2. The cheese packaging film according to claim 1, wherein the inner layer (A) in contact with the cheese is a layer containing 50 mol% or more of a monomer unit based on ethylene. 3. An inner layer (A) which comes into contact with cheese is made of low density polyethylene (LDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene-methacrylic. Acid copolymer (E
MAA), ethylene-acrylic acid copolymer (EAA),
It contains at least one or more resins selected from ethylene-ethyl acrylate copolymer (EEA), and the sealing strength between the layer (A) and the outer surface layer (B) that does not come into contact with the cheese after cheese packaging is improved. The cheese packaging film according to claim 1, wherein the film has a weight of 5 to 600 g / 15 mm. 4. The cheese packaging film according to claim 1, wherein the outer layer (B) that does not contact the cheese is a layer containing 70% of polypropylene or polyester. 5. The cheese packaging film according to claim 1, wherein the outer layer (B) which does not come into contact with the cheese contains 70% of polypropylene or polyester and is a stretched layer. .