JPH07268293A - Protective tape - Google Patents

Abstract

PURPOSE:To obtain a protective tape which can be easily incinerated, is flexible and strong and does not suffer from lifting in drawing CONSTITUTION:A protective tape prepared by forming a layer of a pressure- sensitive adhesive on either surface of a 50-150mum-thick film made of 35-55wt.% ethylene vinyl acetate copolymer containing 3-25wt.% vinyl acetate and having a melt flow rate of 0.5-10g/10min, 10-45wt.% ultralow-density polyethylene having a specific gravity of 0.885-0.92 and a melt flow rate of 0.2-10g/10min and 15-45wt.% polypropylene having a melt flow rate of 0.3-25g/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. PVC (abbreviated as "), low density polyethylene (abbreviated as" LDPE "hereinafter), polypropylene (hereinafter abbreviated as" PP "), thickness 30 to 120
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 film having a thickness of μm 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. When a metal plate is drawn into a shape such as a plate or cup using a protective tape, the stretched part of the tape may return to its original position after the processing and rise up (hereinafter referred to as "floating").
The C-tape also has an advantage that the floating does not easily occur. However, since PVC contains a toxic chlorine element, when it is incinerated at the time of disposal after use, hydrogen chloride gas or black smoke is generated, which is extremely inconvenient especially when a large amount of waste such as construction work is disposed of.

The tape in which the film is made of LDPE only (LDPE tape) does not easily float and does not contain chlorine element, and thus 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. In addition, since the flexibility is insufficient, there is a drawback that it is difficult to attach when the thickness is increased to improve the strength.

The tape whose film is made of only PP (PP tape) has an advantage that it does not easily float, but since it is poor in flexibility, it cannot be used unless it is extremely thin, and its strength is insufficient and the surface to be protected is not covered. Lack of protection features.

[0006]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a protective tape that is easy to incinerate, is flexible and has strength, and does not cause floating during drawing.

[0007]

The gist of the present invention is to provide a protective tape comprising a film and a pressure sensitive adhesive, wherein the film is made of a certain amount of EVA, ultra low density polyethylene (hereinafter abbreviated as "VLDPE") and PP. The resin is made to have a constant thickness.

EVA constituting the above resin contains 3 to 25% by weight of vinyl acetate. If it is less than 3% 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 0.3 to 10
g / 10 minutes. If it is less than 0.3 g / 10 minutes, the viscosity will be too high to form a film, and if it exceeds 10 g / 10 minutes, the viscosity will be too low to form a film.
Limited to the above range. Preferably 0.5 to 8 g / 1
0 minutes. The MFR can be determined according to JIS K 6730.

The EVA is contained in an amount of 35 to 55% by weight based on the whole resin. If it is less than 35% by weight, the film loses flexibility, and if it exceeds 55% by weight, the strength is insufficient, so that the content is limited to the above range. Preferably, it is 40 to 50% by weight.

The VLDPE constituting the above resin is a copolymer obtained by a low pressure polymer method by mixing 10 to 30% by weight of an α-olefin monomer such as propylene, butene, and hexene with ethylene, and has a specific gravity of 0. Those of 885 to 0.92 are used. If the specific gravity is less than 0.885, the strength is insufficient, and if it exceeds 0.92, floating occurs. Therefore, the specific gravity is limited to the above range. It is preferably 0.89 to 0.915.

The MFR of VLDPE is 0.2 to 10
g / 10 minutes. If it is less than 0.2 g / 10 minutes, the viscosity will be too high to form a film, and if it exceeds 10 g / 10 minutes, the viscosity will be too low to form a film, making it difficult to form a film. Preferably 0.3-8 g
/ 10 minutes. The MFR can be determined according to JIS K 6730.

The VLDPE is 10 to 10% of the whole resin.
45% by weight is contained. If it is less than 10% by weight, floating tends to occur, and if it exceeds 45% by weight, flexibility becomes excessive. Therefore, the content is limited to the above range. Preferably 15-
It is 40% by weight.

The PP constituting the above-mentioned resin is not only those obtained by homopolymerizing propylene, but also those obtained by randomly copolymerizing propylene with 5% by weight or less of ethylene, and those obtained by block-polymerizing 10-30% by weight of ethylene with propylene. Although a random copolymer can be used, a random copolymer is preferable because it is easy to mix and rich in flexibility.

The MFR of PP is 0.3 to 25 g / 1.
0 minutes. If it is less than 0.3 g / 10 minutes, the viscosity will be too high to make film forming difficult, and if it exceeds 25 g / 10 minutes, the viscosity will be too low to make film forming difficult. Preferably, 0.5 to 20 g / 1
0 minutes. The MFR can be determined according to JIS K 6758.

The above PP is contained in an amount of 15 to 45% by weight based on the whole resin. If it is less than 15% by weight, the strength will be insufficient, and if it exceeds 45% by weight, the flexibility will be insufficient, so that it is limited to the above range. It is preferably 20 to 40% by weight.

In order to improve the compatibility of the above resins, 3 parts by weight of EVA / VLDPE / PP is used.
˜15 parts by weight of compatibilizer may be used. As the compatibilizer, any commercially available one may be used, and for example, ethylene-propylene rubber, Bennett GR-10 (manufactured by Teikoku Chemical Co., Ltd.) or the like can be used.

To form the film of the present invention, the above E
VA, VLDPE and PP 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 50 to 150 μm. When the thickness is less than 50 μm, the strength is insufficient, and when it exceeds 150 μm, the flexibility is insufficient and floating easily occurs, so that the content is limited to the above range. It is preferably 60 to 130 μm.

The protective tape of the present invention is obtained by laminating an adhesive on the above film. The pressure-sensitive adhesive is not particularly limited, and examples thereof include natural rubber and acrylic resin,
These are, for example, dissolved in a solvent, a bar coater,
It can be laminated by coating with a reverse coater or the like.
A hot melt coating method can also be used.

[0019]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Example 1 Evatate D2021 (vinyl acetate (V
A) Content 10% by weight, melt flow rate 1.5 g / 1
0 minutes, manufactured by Sumitomo Chemical Co., Ltd.) 45 parts by weight, VLDPE by Nakflex DFDA9020 (specific gravity 0.905, melt flow rate 0.85 g / 10 minutes, manufactured by Nippon Unicar Co., Ltd.) 15 parts by weight, and polypropylene as Sumitomo Noblen S131 (ethylene copolymer) Polymerization 3%, melt flow rate 1.2 g / 10 minutes, 40 parts by weight of Sumitomo Chemical Co., Ltd.) were kneaded and blended with a twin-screw extruder to prepare pellets. The pellets were melted at 200 ° C. by a uniaxial extruder and formed into a film having a thickness of 70 μm by an inflation method. Corona discharge treatment was applied to one side of this film. Adhesive is 80 parts by weight of pale crepe # 1, SBR200
20 parts by weight of 1 (manufactured by Zeon Corporation) were kneaded and mixed with a roll, dissolved in toluene to prepare a 20% by weight solution, and 5 parts by weight of YS resin (manufactured by Yasuhara Chemical Co., Ltd.) was added to prepare an adhesive solution. This was coated on one side of the film so as to have a thickness of 10 μm after drying.

Example 2 A protective tape was prepared in the same manner as in Example 1 except that 55 parts by weight of EVA, 20 parts by weight of VLDPE and 25 parts by weight of PP were used. Example 3 A protective tape was prepared in the same manner as in Example 1 except that EVA was 50 parts by weight, VLDPE was 20 parts by weight, and PP was 30 parts by weight. Example 4 A protective tape was produced in the same manner as in Example 1 except that 40 parts by weight of EVA, 40 parts by weight of VLDPE, and 20 parts by weight of PP were used.

Example 5 Evatate D3022 (vinyl acetate (V
A) Content 6% by weight, melt flow rate 7 g / 10 minutes,
A protective tape was prepared in the same manner as in Example 3 except that 50 parts by weight of Sumitomo Chemical Co., Ltd.) was used. Example 6 EVATATE H2031 (Vinyl acetate (V
A) Content 19% by weight, melt flow rate 1.5 g / 1
A protective tape was prepared in the same manner as in Example 3 except that 50 parts by weight of 0 minutes, manufactured by Sumitomo Chemical Co., Ltd.) was used. Example 7 A protective tape was prepared in the same manner as in Example 3 except that 20 parts by weight of Excellen VLEVL730 (specific gravity 0.89, melt flow rate 10 g / 10 minutes, manufactured by Sumitomo Chemical Co., Ltd.) was used as VLDPE.

Example 8 NACKFLEX DEFD-1192 as VLDPE
(Specific gravity 0.912, melt flow rate 0.18 g / 1
A protective tape was prepared in the same manner as in Example 1 except that 15 parts by weight of 0 minutes, manufactured by Nippon Unicar Co., Ltd. was used. Example 9 Sumitomo Noblen D501 (ethylene content 0 as PP
%, Melt flow rate 0.4 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd.), and a protective tape was prepared in the same manner as in Example 1 except that 40 parts by weight was used. Example 10 As PP, 40 parts by weight of Sumitomo Noblen FS8611 (ethylene content 2%, melt flow rate 9 g / 10 min, manufactured by Sumitomo Chemical Co., Ltd.) was used, and the film thickness was 140 μm, and the same procedure as in Example 1 was performed. I made a protective tape.

Example 11 A protective tape was prepared in the same manner as in Example 4 except that the film was formed by the T-die method and the film thickness was 140 μm. Comparative Example 1 EVA 80 parts by weight, VLDPE 8 parts by weight, PP 1
A protective tape was prepared in the same manner as in Example 1 except that the amount was 2 parts by weight. Comparative Example 2 A protective tape was prepared in the same manner as in Example 1 except that EVA was 33 parts by weight, VLDPE was 52 parts by weight, and PP was 15 parts by weight.

Comparative Example 3 A protective tape was prepared in the same manner as in Example 1 except that EVA was 35 parts by weight, VLDPE was 15 parts by weight, and PP was 50 parts by weight. Comparative Example 4 Ultrasen 751 as EVA (vinyl acetate (VA)
Content: 28% by weight, melt flow rate: 6 g / 10 minutes, manufactured by Tosoh Corporation) 45 parts by weight, NACKFLEX DFDA9020 (specific gravity: 0.905, melt flow rate: 0.85 g / 10 minutes, manufactured by Nippon Unicar) as VLDPE 4
0 parts by weight, Sumitomo Noblen S131 as PP (ethylene copolymerization 3%, melt flow rate 1.2 g / 10 minutes,
A protective tape was prepared in the same manner as in Example 1 except that 15 parts by weight of Sumitomo Chemical Co., Ltd.) was used.

Comparative Example 5 Ultrasen 625 (vinyl acetate (VA) as EVA
Content 15% by weight, melt flow rate 14 g / 10 minutes,
40 parts by weight of Tosoh Corporation, LUMITAC 53-1 as VLDPE (specific gravity 0.905, melt flow rate 20)
g / 10 min, manufactured by Tosoh Corporation) 20 parts by weight, and as PP, Mitsui Noblene J3H-G (ethylene content 0%, melt flow rate 15 g / 10 min) 40 parts by weight was used in the same manner as in Example 1. I made a protective tape.

Comparative Example 6 A protective tape was prepared in the same manner as in Example 2 except that the film thickness was 40 μm. Comparative Example 7 Film molding was carried out by the T-die method to give a film thickness of 170.
A protective tape was prepared in the same manner as in Example 1 except that the thickness was changed to μm. Comparative Example 8 A PVC protective tape (SPV-224 manufactured by Nitto Denko Corporation, film thickness 70 μm, adhesive thickness 10 μm) was prepared.

Comparative Example 9 LDPE Sumikasen F200 (manufactured by Sumitomo Chemical Co., Ltd.) was inflation-molded at a temperature of 165 ° C. by an extruder to obtain a 100 μm film, and a protective tape was prepared in the same manner as in Example 1 below. Comparative Example 10 A PP-based protective tape (SPV-S300 manufactured by Nitto Denko Corporation, film thickness 35 μm, adhesive thickness 5 μm) was prepared.

The protective tapes of Examples 1 to 11 and Comparative Examples 1 to 10 were evaluated by the following evaluation methods, and the results are shown in Tables 1 and 2. Evaluation method 1. Flexibility A 10% modulus was used. Measurement is JIS K 673
2 Based on the tensile breaking strength of "Agricultural polyvinyl chloride film".

2. Strength According to JIS K 6718 "Surface hardness test of methacrylic resin plate". A load was placed on the needle, and a tape was attached to the stainless plate to confirm the presence of scratches on the stainless plate. The judgment was based on the following criteria. ◯: No damage with 800 g load Δ: No damage with 400 g load ×: Scratch with 400 g load

3. Floating after drawing processing Stainless steel plate with 100 mm diameter and 0.5 mm thickness (SU
A protective tape was attached to S304) and left for 30 minutes. 20t
50mm in diameter at the center of stainless plate with a press machine of 1 depth
A 5 mm drawing process was performed to form a hat shape. At this time, the surface of the protective tape was attached to the concave surface. The floating state of this protective tape was observed. ◯: No floating after 30 minutes. Δ: No floating after 5 minutes, but after 30 minutes ×: Immediately after, floating occurred.

4. Film moldability When the film can be formed by the inflation method or the T-die method with an extrusion molding machine, it is evaluated as “OK”, and when it cannot be formed, it is evaluated as “NO”.

5. Presence or absence of harmful elements Halogen element, CN group or N that generates hydrogen cyanide
When a nitrogen element that generates O ₂ was included, it was evaluated as “present”, and when it was not included, it was evaluated as “absent”.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

EFFECTS OF THE INVENTION According to the present invention, a protective tape which is flexible and easy to attach, has strength and is not easily torn, protects the metal plate of the base material from scratches during transportation and processing, and does not easily float when drawn. Can be obtained from a material that does not contain harmful elements and is easily incinerated.

Claims (1)

[Claims] 1. An ethylene vinyl acetate copolymer having a melt flow rate of 0.5 to 10 g / 10 minutes and a specific gravity of 0.8.
85 to 0.92 and a melt flow rate of 0.2 to 1
10 to 45% by weight of ultra low density polyethylene of 0 g / 10 minutes and a melt flow rate of 0.3 to 25 g / 1
A protective tape, which is obtained by laminating an adhesive on one side of a film having a thickness of 50 to 150 μm and made of 15 to 45% by weight of polypropylene which is 0 minutes.