JP2002086632A - Stretch film having rustproof function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretch film good in both of close adhesiveness and strength and having a good rustproof function. SOLUTION: The stretch film has at least one layer comprising a resin composition containing a gasifiable rustproof agent and a value of the tackiness(T)/ stiffness(S) of the film is 1.0-5.0. This stretch film has excellent adhesion, generates no breakage and has rustproof function.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch film used for packing an article such as a metal product which requires prevention of rust.

[0002]

2. Description of the Related Art When storing or transporting an article such as a metal product, rust-proof packaging is performed to prevent rust. And, in the case of metal products, after packing with paper impregnated with a vaporizable rust preventive agent, further pack with synthetic resin film to prevent moisture intrusion, dissipation of rust preventive agent, tearing of rust preventive paper, etc. Alternatively, rust-preventive oil is applied on a metal surface and then packed with a synthetic resin film. In addition, in order to reduce and simplify packaging materials, a stretch film made of a synthetic resin containing a vaporizable rust inhibitor has been increasingly used.

[0003] In such a packaging form, in order to prevent the generation of rust, it is necessary to secure the hermeticity, that is, to prevent moisture from entering the inside of the package and dissipation of the vaporizable rust inhibitor outside the package. It is extremely important. When wrapping the stretch film, a part of it is wrapped so that it overlaps the part that was wrapped earlier, but if the film does not adhere to this overlapping part, moisture will enter and cause rust. Become. In addition, when the packaged object is a metal coil, the outer periphery is a curved surface, and if the film does not have appropriate elongation and flexibility, the film does not adhere along the curved surface and a gap is generated, which causes rust. If the film is wrapped not only on the outer periphery of the metal coil but also on the inner gap, the wrinkles may occur due to the difference in the surface length between the outer and inner peripheries when wrapping the end face of the coil. It is generated and creates a gap, which is likely to cause rust. However, conventional stretch films often use a resin having high rigidity in order to increase strength, and there are problems with the adhesion, elongation and flexibility of the film, and many of them have insufficient sealing properties.

[0004]

In order to improve the sealing performance of a rustproof package using a stretch film, a method of improving the adhesiveness of the film itself and a method of increasing the flexibility of the film to follow the shape of the article to be packaged. By doing so, a method of preventing air from entering between the film and the packaged object can be considered. However, in the former case, if the adhesiveness is too strong, it is difficult to draw out the film from the roll and workability is deteriorated, and in the latter case, if the flexibility is increased too much, the strength of the film itself is weakened, and breakage and perforation are caused. It occurs and cannot be sealed. Therefore, there is a demand for a stretch film having an excellent rust-preventing function in both adhesion and strength.

[0005]

The inventor of the present invention has conducted various studies to solve the above-mentioned problems. As a result, the value of the stiffness of the film obtained from the tensile modulus and the thickness is divided by the value of the adhesiveness of the film. It has been found that a stretch film excellent in both adhesiveness and strength can be obtained when the obtained numerical value is within a certain range, and the present invention has been completed. That is, the present invention provides a stretch film having excellent rust-preventing function with excellent sealing performance by controlling the adhesiveness of the film and the stiffness of the film.

The tackiness (T) of the film in the present invention is a value determined by the following measuring method. The two films are laminated in such a manner that the front and back surfaces are in contact with each other, and cut into a strip having a length of 100 mm and a width of 50 mm. This is 40
g / cm ² at a temperature of 23 ° C. and a humidity of 50%.
The sample left for 4 hours is used as a measurement sample. Using a tensile tester, the film was pulled at a test speed of 300 mm / min so that each film of the measurement sample was peeled in the direction of 90 °, and the value obtained by doubling the average load at that time was determined as the adhesiveness (g / 100m).
m).

[0007] The stiffness of the film in this patent is a numerical value obtained by the following formula. Waist (S) of film = [tensile elastic modulus (Kg / cm ² )] ×
[Thickness (mm)] ³ × 100 * 100 is a constant The tensile modulus used is a value measured based on JIS K7127 (tensile test method for plastic films and sheets). That is, using a No. 1 test piece having a width of 10 mm as a test piece, measurement is performed at a test speed of 5 mm / min using a tensile tester, and the stress-strain curve is obtained from an initial straight line portion. As the thickness, a value measured based on JIS K7130 (thickness measuring method for plastic films and sheets) is used.
The measuring method may be any of the A method (instrument method), the B method (mass method), and the C method (electromagnetic / electromagnetic wave method), but the A method using a dial gauge is preferable. The stiffness (S) of the film is determined from the obtained tensile modulus and the thickness of the film. The larger the value, the stronger (hard) the film is, and the smaller the value, the weaker (soft) the film. Since this parameter is represented by the product of the tensile modulus and the film thickness, it can be controlled by the following method. That is, in order to lower the stiffness (S) of the film, the elastic modulus is reduced or the thickness of the film is reduced by selecting and modifying the type of resin used. In order to increase the stiffness (S) of the film, the elastic modulus is increased or the thickness of the film is increased by selecting and modifying the type of resin used.

[0008] The above-mentioned adhesiveness (T) is determined by the film's waist (S).
Is smaller than 1.0, the film is too stiff compared to the adhesiveness, and the film cannot follow the shape of the packaged object, so that it is difficult to seal the film. 5.0
If it is larger, the film is too sticky to the waist of the film, which hinders the feeding of the film. 1.0-
When it is in the range of 5.0, appropriate adhesiveness and flexibility of the film can be obtained, so that the packaged object can be securely sealed.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The stretch film having a rustproofing function of the present invention has at least one layer made of a resin composition containing a vaporizable rustproofing agent. An adhesive can be applied to the surface of the film to impart tackiness.
Further, a layer made of a resin composition containing an adhesive may be provided.

The material of the stretch film having a rustproofing function of the present invention is not particularly limited, but synthetic resins such as polyethylene resin and polypropylene resin can be used, and ethylene / α-olefin copolymer is preferable. Further, in order to adjust the stiffness of the film, a multilayer film made of different materials may be used. When using a layer made of a resin composition containing an adhesive to impart tackiness, the material of this layer is not particularly limited, polyethylene-based resin,
A synthetic resin such as a polypropylene resin can be used, and it is preferable to use an ethylene / vinyl acetate copolymer.

The pressure-sensitive adhesive used in the stretch film having a rust-preventing function of the present invention is not particularly limited, but may be one or more of liquid aliphatic hydrocarbon resin, terpene resin, cumarone-indene resin, petroleum resin and the like. Two or more types can be used as a mixture, and it is preferable to use a liquid aliphatic hydrocarbon resin.

The rust preventive used in the present invention is not particularly limited, but includes an organic carboxylate amine salt, an amine nitrite salt,
One or more kinds of amine phosphate salts, amine carbonates, benzotriazole derivatives, heterocyclic amines, etc. can be used as a mixture, and appropriate ones can be used depending on the type of metal product etc. to be packaged. use.

Since the stretch film having a rustproofing function of the present invention may be used outdoors, an ultraviolet absorber, a weathering agent and the like may be added as necessary.

[0014]

Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples.

Evaluation method: Adhesion Two films are adhered in such a manner that the front and back surfaces are in contact with each other, and cut into a strip having a length of 100 mm and a width of 50 mm. A load of 40 g / cm ² was applied to this, and the temperature was 23 ° C. and the humidity was 50%.
The sample left for 24 hours is used as a measurement sample. Using a tensile tester, the test sample was pulled at a test speed of 300 mm / min so that each film of the test sample was peeled in the direction of 90 °, and the value obtained by doubling the load at that time was regarded as the adhesiveness (g / 100m).
m).

Waist of film Film waist (S) = [tensile elastic modulus (Kg / cm ² )] ×
[Thickness (mm)] ³ × 100 * 100 is a constant The tensile modulus used is a value measured based on JIS K7127 (tensile test method for plastic films and sheets). That is, using a No. 1 test piece having a width of 10 mm as a test piece, measurement is performed at a test speed of 5 mm / min using a tensile tester, and the stress-strain curve is obtained from an initial straight line portion. As the thickness, a value measured based on JIS K7130 (thickness measuring method for plastic films and sheets) is used.
The measurement method may be any of the A method (instrument method), the B method (mass method), and the C method (electromagnetic / electromagnetic wave method), but the A method using a dial gauge is preferable.

Packaging Suitability A coil-wound electromagnetic steel sheet (coil diameter 11
75 mm and a width of 1050 mm) were wrapped, and the film was observed for adhesion when wrapped and for the presence or absence of film breakage. If the film is not completely adhered, the sealing state cannot be maintained, so moisture will enter from there and rust on the package inside, and when the film is cut open with a cutter etc. and opened, the film It takes time and effort to collect used films because of the separation of If the film breaks, it will not be possible to pack it, which will hinder the packing operation. If a hole is formed in the film, moisture will enter through the film, resulting in rust on the packaged object inside.

Adhesiveness Whether the films after packaging are tightly adhered to each other, and whether the films can be kept in close contact with each other when unveiled. ：: The films after packaging are tightly adhered to each other, and even when the film is unveiled, the film is kept in close contact. X: The film after packaging does not adhere to each other to form a gap, and the film is separated when the film is opened. Whether the film breaks Whether the film breaks before completely wrapping one coil. ：: Packaging can be performed without breaking the film. X: The film breaks partly or over the entire width during packaging.

Example 1 As a rust preventive layer (A), an ethylene / α-olefin copolymer (Sumikacene EFV201, manufactured by Sumitomo Chemical Co., Ltd .; MF)
R = 1.5 g / 10 min, density = 0.915 g / cm ³ )
97 parts by weight and a vaporizable rust inhibitor (manufactured by CORTEC Co.)
VCI-126) 3.0 parts by weight of a resin composition, and (B) an ethylene-vinyl acetate copolymer (Evatate H2081 manufactured by Sumitomo Chemical Co., Ltd .; MF) as an adhesive layer
R = 2.0 g / 10 min, density = 0.93 g / cm ³ , vinyl acetate content 15%) 92 parts by weight and liquid polyisobutylene as an adhesive (Nippon Oil Co., Ltd. Nisseki Polybutene HV)
-50) Using a resin composition consisting of 8 parts by weight, melt-kneading each with an extruder having a diameter of 50 mm and an L / D of 32, and coextruding inflation to obtain a total layer thickness of 60 μm and a ratio of each layer thickness (rust prevention). (Layer / adhesive layer) A two-layer film of 4/1 was prepared.

Example 2 An ethylene / α-olefin copolymer (Sumikasen EFV10 manufactured by Sumitomo Chemical Co., Ltd.) was used as a surface rust-preventing layer (A1).
2: MFR = 1.0 g / 10 min, density = 0.930 g /
cm ³ ) 98 parts by weight and a volatile rust inhibitor (CORTECC)
o. VCI-126), a resin composition consisting of 2.0 parts by weight, and ethylene · α as an internal rust preventive layer (A2).
-Olefin copolymer (Sumikasen EFV203 manufactured by Sumitomo Chemical Co., Ltd .; MFR = 2.0 g / 10 min, density =
0.912 g / cm ³ ) Adhesive layer (B) using a resin composition consisting of 96 parts by weight and 4.0 parts by weight of a vaporizable rust inhibitor
As ethylene-vinyl acetate copolymer (Evatate H2081 manufactured by Sumitomo Chemical Co., Ltd .; MFR = 2.0 g / 1)
0 min, density = 0.93 g / cm ³ , vinyl acetate content 15
%) 92 parts by weight and liquid polyisobutylene as an adhesive (Nippon Oil Co., Ltd. Nisseki polybutene HV-50) 8
Using a resin composition consisting of parts by weight, each having a diameter of 5
0 mm, melt-kneading with an extruder having an L / D of 32, and a total thickness of 60 μm by a co-extrusion inflation method, and each layer thickness ratio (surface rust prevention layer / internal rust prevention layer / adhesive layer) 1/3/1. A layer of film was made.

Example 3 As a rust preventive layer (A), an ethylene / α-olefin copolymer (Sumikacene EFV201 manufactured by Sumitomo Chemical Co., Ltd .; MF)
R = 1.5 g / 10 min, density = 0.915 g / cm ³ )
97 parts by weight and a vaporizable rust inhibitor (manufactured by CORTEC Co.)
VCI-126) 3.0 parts by weight of a resin composition, and (B) an ethylene-vinyl acetate copolymer (Evatate H2081 manufactured by Sumitomo Chemical Co., Ltd .; MF) as an adhesive layer
R = 2.0 g / 10 min, density = 0.93 g / cm ³ , vinyl acetate content 15%) 90 parts by weight and liquid polyisobutylene as an adhesive (Nippon Oil Co., Ltd. Nisseki Polybutene HV)
-50) Using a resin composition consisting of 10 parts by weight, melt-kneading each with an extruder having a diameter of 50 mm and an L / D of 32, and coextruding inflation to obtain a total layer thickness of 50 μm and a ratio of each layer thickness (rust prevention). (Layer / adhesive layer) A two-layer film of 4/1 was prepared.

Comparative Example 1 As an antirust layer (A), an ethylene / α-olefin copolymer (Sumikasen EFV102, manufactured by Sumitomo Chemical Co., Ltd .; MF)
R = 1.0 g / 10 min, density = 0.930 g / cm ³ )
Except for using a resin composition comprising 98 parts by weight and 2.0 parts by weight of a vaporizable rust inhibitor, the same procedure as in Example 1 was carried out to obtain a total layer thickness of 6 parts.
A 0 μ, two layer film was made.

Comparative Example 2 As the adhesive layer (B), an ethylene / vinyl acetate copolymer (Evatate H2081 manufactured by Sumitomo Chemical Co., Ltd .; MFR)
= 2.0 g / 10 min, density = 0.93 g / cm ³ , vinyl acetate content 15%) 99 parts by weight and liquid polyisobutylene as an adhesive (Nippon Oil Co., Ltd. Nisseki Polybutene HV-)
50) Except for using the resin composition consisting of 1 part by weight, a two-layer film was prepared in the same manner as in Example 1 except that the total layer thickness was 60 μm and each layer thickness ratio (rust preventive layer / adhesive layer) was 4/1. .

Comparative Example 3 The same resin composition as in Example 1 was used for the adhesive layer and the rust preventive layer.
A film having a total thickness of 30 μm and two layers was prepared.

Table 1 shows the results of testing the films of Examples 1 to 3 and Comparative Examples 1 to 3 for the adhesion and the presence or absence of breakage. It can be seen that, unlike the films of Comparative Examples 1-3, the films of Examples 1-3 have excellent adhesion and no breakage.

[0026]

[Table 1]

[0027]

As can be seen from the above results, according to the present invention, a stretch film having excellent adhesion and no breakage and having a rustproofing function can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 5/16 C08K 5/16 C08L 101/00 C08L 101/00 F term (Reference) 3E067 AA11 AB49 AB99 BA17A BB25A CA02 CA30 GB20 3E086 AD17 BA02 BA04 BA15 BB12 BB90 CA32. JL13C JL13G 4J002 BB012 BB031 BB051 BB061 BB121 BK002 CE002 EN006 FD206 FD342

Claims (2)

[Claims] Claims: 1. A film having at least one layer comprising a resin composition containing a volatile rust inhibitor, wherein the value of the adhesiveness (T) of the film / the stiffness (S) of the film is 1.0 to 5.0. A stretch film having a rustproofing function. 2. A film having a thickness of 30 μm, comprising at least two layers of a rust-preventive layer (A) composed of a resin composition containing a vaporizable rust-preventive agent and an adhesive layer (B) composed of a resin composition containing a pressure-sensitive adhesive.
The stretch film according to claim 1, which has a thickness of from 200 to 200 µm.