JPH07268294A - Protective tape - Google Patents

Abstract

PURPOSE:To obtain a protective tape which can be easily incinerated. and is sufficiently strong and flexible. CONSTITUTION:A protective tape prepared by forming a 5-20mum-thick layer of a pressure-sensitive adhesive on either surface of a 40-200mum-thick film made of 40-75wt.% ethylene/vinyl acetate copolymer containing 5-25wt.% vinyl acetate and having a melt flow rate of 0.5-18g/10 min and 25-60wt.% linear low-density polyethylene having a specific gravity of 0.915-0.935 and a melt flow rate of 0.5-5g/10min.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective tape used for protecting a surface of a metal plate, a plastic plate, a glass plate, etc. during transportation, storage, press working and molding.

[0002]

2. Description of the Related Art A protective tape used for surface protection during transportation, storage, press working (drawing, punching, bending) of metal plates, plastic plates, glass plates, etc. Also called "PVC"),
Low-density polyethylene (hereinafter also referred to as "LDPE"), polypropylene (hereinafter also referred to as "PP"), thickness 30 to
It is used by applying a pressure-sensitive adhesive based on natural rubber or acrylic resin having a thickness of 5 to 20 μm on one side of a 120 μm film and processing it into a tape.

A tape (PVC tape) in which the above film is made of only PVC is excellent in flexibility so that it can be easily attached to the surface of an object to be protected such as a metal plate. Hateful. But PV
Since C contains a toxic chlorine element, when it is incinerated at the time of disposal after use, hydrogen chloride gas and black smoke are generated, which is extremely inconvenient especially when a large amount of waste such as construction work is disposed of.

The film is composed of LDPE only (L
Since the DPE tape) does not contain chlorine element, it does not have the above-mentioned drawbacks. However, since LDPE has low strength and is easily broken, it lacks the function of protecting the protected surface. Also,
Since the flexibility is insufficient, increasing the thickness to improve the strength makes it difficult to attach.

Japanese Unexamined Patent Publication No. 63-5679 discloses a laminated film of a linear LDPE (hereinafter also referred to as "L-LDPE") and a high density polyolefin resin (high density polyethylene, high density polypropylene, etc.). By the way, although this one solves the above problems in terms of strength, the flexibility is not improved.

[0006]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a protective tape which is easy to incinerate and has sufficient strength and flexibility.

[0007]

SUMMARY OF THE INVENTION The gist of the present invention is to construct a protective tape in which a resin consisting of a certain amount of ethylene vinyl acetate copolymer and a certain amount of linear low density polyethylene has a certain thickness. The adhesive is laminated on one side of the film to a certain thickness. The present invention will be described in detail below.

EVA constituting the above resin contains 5 to 25% by weight of vinyl acetate. If it is less than 5% by weight, the flexibility is insufficient, and if it exceeds 25% by weight, the strength is insufficient, so that the content is limited to the above range. The EVA has a melt flow rate (hereinafter, also referred to as “MFR”) of 0.5 to 18
g / 10 minutes. If it is less than 0.5 g / 10 minutes, the viscosity will be too high to make film forming difficult, and if it exceeds 18 g / 10 minutes, the viscosity will be low and film forming will be difficult.
Limited to the above range. Preferably 0.6 to 15 g /
10 minutes. The MFR can be determined according to JIS K 6730.

The EVA is contained in an amount of 40 to 75% by weight based on the whole resin. When it is less than 40% by weight, the film loses flexibility, and when it exceeds 75% by weight, the strength is insufficient, so that the content is limited to the above range. Preferably, it is 45 to 70% by weight.

The L-LDPE constituting the above resin is a copolymer obtained by a low pressure polymer method by mixing 4 to 10% by weight of an α-olefin monomer such as propylene or 1-butene with ethylene, and has a specific gravity. Those of 0.915 to 0.935 are used. When the specific gravity is less than 0.915, the strength is insufficient, and when the specific gravity is more than 0.935, the flexibility is insufficient. Therefore, the specific gravity is limited to the above range. Preferably 0.918 to 0.930
Is.

The MFR of the L-LDPE is 0.5 to 5
g / 10 minutes. If it is less than 0.5 g / 10 minutes, the viscosity will be too high to form a film, and if it exceeds 5 g / 10 minutes, the viscosity will be too low to form a film. Preferably 0.6-3 g
/ 10 minutes.

The above L-LDPE is 25 to 6 of the total resin.
0 wt% is included. If it is less than 25% by weight, the strength is insufficient, and if it exceeds 60% by weight, the flexibility is insufficient, so that the content is limited to the above range. It is preferably 30 to 55% by weight.

A compatibilizing agent may be added to the resin composed of EVA and L-LDPE. The compatibilizer is not particularly limited, and examples thereof include Bennett GR-10 (manufactured by Teikoku Kagaku) and GR-25 (manufactured by Teikoku Kagaku). The compatibilizer may be added in an amount of 10% by weight or less, preferably 5% by weight or less, based on the resin. In addition to the compatibilizer, an ultraviolet absorber, a light stabilizer and the like can be added to the resin in order to improve weather resistance. Further, an antioxidant or the like may be added to facilitate processing.

To form the film of the present invention, the above E
VA and L-LDPE are blended by a commonly used method, for example, a method using a twin-screw extruder or the like to produce pellets, and the pellets are produced by, for example, inflation molding, T-die method, calender method or the like. The above film can be obtained by molding. The film has a thickness of 40 to 200 μm. If it is less than 40 μm, the strength is insufficient, and if it exceeds 200 μm, the flexibility is insufficient. Therefore, it is limited to the above range. Preferably 50
˜140 μm.

The protective tape of the present invention is obtained by laminating an adhesive on the above film to a thickness of 5 to 20 μm. If it is less than 5 μm, a sufficient adhesive effect cannot be obtained, and if it exceeds 20 μm, the adhesive strength becomes too strong and the tape cannot be peeled off when a metal plate is used. The pressure-sensitive adhesive is not particularly limited, and examples thereof include natural rubber and acrylic resin, which can be laminated in such a manner that they are dissolved in a solvent or the like and coated with a bar coater, a reverse coater or the like. . A hot melt coating method can also be used.

[0016]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Examples 1 to 3 Evatate D20 as EVA at the compounding ratios shown in Table 1
21 (vinyl acetate (VA) content 10% by weight, melt flow rate 1.5 g / 10 minutes, manufactured by Sumitomo Chemical Co., Ltd.), LL
Nipolone-LF-10 as DPE (specific gravity 0.919,
A melt flow rate of 0.8 g / 10 minutes (manufactured by Tosoh Corporation) was used and mixed, and then a film having a thickness of 70 μm was obtained by an inflation method using an extruder. Die temperature is 18
It was 0 ° C. Separately, 80 parts by weight of pale crepe # 1 and 20 parts by weight of SBR2001 (manufactured by Zeon Corporation) were kneaded and mixed with a roll, and then dissolved in toluene to prepare a 20% solution, and YS resin 115 (manufactured by Yasuhara Yushi Co., Ltd.) was prepared. An adhesive solution was prepared by adding 5 parts by weight. After performing corona discharge treatment on the film, the film was dried, and the pressure-sensitive adhesive solution was applied on the surface so as to have a thickness of 10 μm after drying to form a protective tape.

Example 4 Ultrasen 631 as EVA (vinyl acetate (VA))
Content 20% by weight, melt flow rate 1.5 g / 10
Min., Manufactured by Tosoh Co., Ltd.) and having the formulation shown in Table 1, and a protective tape was prepared in the same manner as in Example 1 except that a film having a thickness of 140 μm was formed at a T-die temperature of 180 ° C. by an extruder.

Example 5 Ultrasen 625 as EVA (vinyl acetate (VA))
Content 15% by weight, melt flow rate 14 g / 10 minutes,
A protective tape was prepared in the same manner as in Example 1 except that the composition shown in Table 1 was used and the film thickness was 100 μm.

Example 6 Nipolone-LF-25R (specific gravity: 0.
930, melt flow rate 2 g / 10 minutes, manufactured by Tosoh Corporation), and the composition shown in Table 1 was used, and the film thickness was 50.
A protective tape was produced in the same manner as in Example 2 except that the thickness was changed to μm.

Comparative Example 1 A protective tape was prepared in the same manner as in Example 1 except that Ultrasen 625 was used as EVA, the composition was as shown in Table 2, and the film thickness was 50 μm. Comparative Example 2 Ultrasen 625 as EVA and Sholex Linear 107L-A as L-LDPE (specific gravity 0.91)
6, melt flow rate 6g / 10min, Showa Denko)
Was used to prepare the protective tape in the same manner as in Example 1 except that the composition was as shown in Table 2 and the film thickness was 50 μm. Comparative Example 3 Ultrasen 751 as EVA (vinyl acetate (VA)
Example 1 except that the content was 28% by weight, the melt flow rate was 6 g / 10 minutes, manufactured by Tosoh Corporation, and the formulation shown in Table 2 was used.
A protective tape was prepared in the same manner as in.

Comparative Example 4 EVATATE H4011 (Vinyl acetate (V
A) Content 20% by weight, melt flow rate 20 g / 10
Min., Manufactured by Sumitomo Chemical Co., Ltd.) as L-LDPE
A protective tape was prepared in the same manner as in Example 1 except that the composition shown in Table 2 was used using LF-25R, and the film thickness was 160 μm. Comparative Example 5 Nipolone-LM-50 (specific gravity 0.9 as L-LDPE)
35, melt flow rate 3 g / 10 minutes, manufactured by Tosoh Corporation)
A protective tape was prepared in the same manner as in Example 1 except that the composition shown in Table 2 was used.

Comparative Example 6 A protective tape was prepared in the same manner as in Example 1 except that only Nipolone-LF-10 which was L-LDPE was used. Comparative Example 7 A protective tape was prepared in the same manner as in Example 1 except that only EVA Tate D2021 was used and the die temperature was 140 ° C.

Comparative Example 8 Example 1 was repeated except that a film was obtained at a die temperature of 165 ° C., using only LDPE, petrosene 172 (specific gravity 0.920, melt flow rate 0.3 g / 10 minutes, manufactured by Tosoh Corporation). A protective tape was prepared in the same manner as in. Comparative Example 9 PVC protective tape SPV-202 (film thickness 120 μm, manufactured by Nitto Denko Corporation) was prepared.

Evaluation method 1. Flexibility It conforms to JIS K 7106 "Testing method for bending stiffness of plastic by cantilever". Films before being made into a tape were laminated and hot-pressed at 150 ° C. to prepare a sample having a thickness of 2.0 ± 0.2 mm, a width of 13 mm and a length of 60 mm and tested. The PVC protective tape of Comparative Example 9 was tested by removing the adhesive with toluene. 2. Tensile strength JIS K 6732 “Agricultural polyvinyl chloride film” was used, and a film before being used as a tape was used.
The PVC protective tape of Comparative Example 9 was tested by removing the adhesive with toluene.

3. Surface strength: JIS K 6718 “methacrylic resin plate” surface hardness test method was applied. The following load was applied to the scratching needle and scratched on the stainless steel plate to which the tape was attached. The tape was peeled off and the scratches on the stainless steel plate were examined, and the judgment was made as follows. Good: No scratches up to 600 g. B: No damage at 400 g, but scratches at 600 g. X: There are scratches at 400 g. 4. Presence or absence of harmful elements When halogen or chlorine is contained, it is evaluated as "Yes", and when it is not contained, it is evaluated as "No".

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

EFFECTS OF THE INVENTION According to the present invention, it can be easily incinerated without containing harmful elements, has flexibility, is easy to stick, and has strength.
It is possible to obtain a protective tape with high performance for protecting metal plates, plastic plates, etc. from scratches.

Claims (1)

[Claims] 1. An ethylene-vinyl acetate copolymer having a melt flow rate of 0.5 to 18 g / 10 min, containing vinyl acetate in an amount of 5 to 25% by weight, and an ethylene vinyl acetate copolymer in an amount of 40 to 75% by weight, and a specific gravity of 0.915 to 0. 0.935 and a melt flow rate of 0.5 to 5 g / 10 min, and a pressure-sensitive adhesive of 5 to 20 μm on one side of a film of 40 to 200 μm in thickness composed of 25 to 60% by weight of linear low-density polyethylene. A protective tape characterized by being laminated on.