JP2012077226A - Surface-protective adhesive sheet for punching and drawing processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-protective adhesive sheet for punching and drawing processing which remarkably reduces the occurrence of the tear and ironing breakage of a surface-protective adhesive sheet when a metallic plate or the like to which the surface-protective adhesive sheet sticks is subjected to punching and drawing processing.SOLUTION: In the surface-protective adhesive sheet for punching and drawing processing, an adhesive sheet has a base layer and an adhesive layer which exists on one face of the base layer. The base layer comprises at least two layers, and each of the layers of the base layer is a non-stretched plastic film, and the two layers are a polyamide film layer and a polyolefin film layer, respectively.

Description

  The present invention relates to a surface-protective pressure-sensitive adhesive sheet, and more particularly to a surface-protective pressure-sensitive adhesive sheet that prevents scratches on a molded product during stamping or drawing.

  Conventionally, surface protective adhesive sheets have been used to prevent scratches and dirt on the surface of stainless steel plates, aluminum plates, steel plates, plastic plates, decorative plywood, etc. during transportation, storage or molding. As such a surface protective adhesive sheet, Patent Document 1 (Japanese Patent Publication No. Sho 59-49953), Patent Document 2 (Japanese Patent Laid-Open Publication No. 56-55252), Patent Document 3 (Japanese Patent Publication No. Sho 50-14667), and Patent Document 4 (Japanese Patent Laid-Open Publication No. 2005-249542). Japanese Patent Laid-Open No. 50-52141) and the like are known.

  In general, the surface protective adhesive sheet for bending, punching or drawing of metal plates should not be peeled off from the adherend during molding (temporary adherence) and can be easily done without trouble after work. It must be peelable (removability). In the punching process, when a punch press is used, the punching residue in the punch press lower die after punching rises in the same manner as the punch press upper die rises, Damage to the surface of the metal plate (upper surface and / or lower surface) by riding on the surface of the metal plate or entering between the workpiece and the lower die and then pressing the entire waste with the upper die during punching. Therefore, in addition to the above request, it is also required not to generate debris after punching.

  In order to meet the above requirements, Patent Document 5 (Japanese Patent Laid-Open No. 62-201985), Patent Document 6 (Japanese Patent Publication No. 57-11343), and Patent Document 7 (Japanese Patent Laid-Open No. 6-108023) have been proposed. However, these surface protective pressure-sensitive adhesive sheets are insufficient in temporary attachment and removability, and there is a problem in practical use because debris is observed at the time of punching.

Japanese Patent Publication No.59-49953 JP-A-56-55252 Japanese Patent Publication No. 50-14667 JP 50-52141 A JP-A-62-201985 Japanese Patent Publication No.57-11343 JP-A-6-108023

  The object of the present invention is to provide punching and drawing surface protection that significantly reduces the occurrence of tearing and smashing of the surface protecting adhesive sheet when punching a metal plate or the like to which a surface protecting adhesive sheet has been attached. It is to provide an adhesive sheet.

  The present inventor has arrived at the present invention while earnestly studying the surface protective tape or surface protective sheet for drawing from a viewpoint different from the above proposal.

That is, the present invention (1) is a pressure-sensitive adhesive sheet having a support layer and a pressure-sensitive adhesive layer present on one surface thereof.
The support layer consists of at least two layers,
Each layer of the support layer is an unstretched plastic film,
The two layers are a polyamide film layer and a polyolefin film layer, and are a surface protective pressure-sensitive adhesive sheet for punching and drawing.

  The present invention (2) is the surface protective pressure-sensitive adhesive sheet for punching and drawing according to the invention (1), wherein the polyamide film layer is made of an aliphatic polyamide resin.

  The present invention (3) is the surface protective pressure-sensitive adhesive sheet for stamping / drawing process of the invention (1) or (2), wherein the polyolefin film layer is made of a polypropylene resin.

  In the present invention (4), the elastic modulus of the support layer is 500 to 800 MPa, the breaking strength of the support layer is 50 to 90 N / 20 mm, and the tear strength of the support layer is 5 to 10 N. It is the surface protective sheet for punching / drawing process according to any one of the inventions (1) to (3).

  The invention (5) is any one of the inventions (1) to (4), wherein the pressure-sensitive adhesive layer side of the support layer is a polyolefin film layer, and the surface layer side opposite to the pressure-sensitive adhesive layer is a polyamide film layer. This is a surface protection adhesive sheet for punching and drawing.

  The surface protective pressure-sensitive adhesive sheet of the present invention can remarkably improve the occurrence of tearing and ironing of the surface protective sheet when a metal plate or the like to which the pressure-sensitive adhesive sheet is attached is punched and drawn. Further, the occurrence of sheet waste can be suppressed by preventing the occurrence of tearing and ironing.

  Hereinafter, the present invention will be described in detail.

1. Support layer The support layer of the present invention comprises at least two layers. Each layer of the support layer is an unstretched plastic film, and the two layers are a polyamide film layer and a polyolefin film layer. By adopting such a configuration, even when the thickness is the same, it is possible to remarkably improve tearing during punching and drawing compared to the case of one layer. Further, the defect of one layer can be compensated for by the other layer, and the overall physical properties can be improved. That is, it is considered that the occurrence of sheet tearing and ironing tears is suppressed during drawing by the synergistic effect related to the combination of the high-strength polyamide film and the highly followable polyolefin film. As a result, the occurrence of sheet residue can be prevented, and the surface of the molded product is hardly damaged.

  Each layer of the support layer is composed of an unstretched plastic film. Since the plastic film of each layer is stretched integrally with the metal plate in the drawing process, the support layer has good extensibility, and an unstretched one that plastically deforms is preferably used. One of the outermost layers of the support layer is a polyamide film. The film shows a high value for both strength and elongation, which is preferable. The other outermost layer of the support layer is an unstretched polyolefin film. The film is preferable from the viewpoint of followability, cost, and availability. Thus, tearing can be prevented by using an unstretched plastic film.

  The polyamide film contains a polyamide-based resin. The polyamide resin constituting the polyamide film is preferably an aliphatic polyamide resin, and may contain other polyamide resins such as an alicyclic polyamide resin and an aromatic polyamide resin within 20 parts by weight. Examples of the aliphatic polyamide resin include nylon 6, nylon 11, nylon 12, nylon 6,6, nylon 6,10 and the like. In particular, nylon 6 may be used from the viewpoint of physical properties, versatility, cost, and the like. preferable.

  The polyolefin film contains a polyolefin resin. Examples of the polyolefin resin used for the polyolefin film include homopolymers of α-olefins having 2 to 12 carbon atoms such as ethylene, propylene, and 1-butene, or copolymers with vinyl compounds. It is not limited. More specifically, low-density polyethylene, high-density polyethylene, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, ethylene / 1-octene copolymer, ethylene / 4-methyl-1-pentene Copolymers, ethylene / vinyl acetate copolymers, ethylene / acrylic acid copolymers, ethylene / methacrylic acid copolymers, ethylene / acrylic acid ester copolymers, ethylene / methacrylic acid ester copolymers, etc. And polypropylene, propylene / ethylene copolymer, propylene polymer such as propylene / 1-butene copolymer, poly 1-butene, poly 1-hexene, poly 4-methyl-1-pentene, etc. These polyolefin resins may be used singly or in combination of two or more. As the polyolefin resin, polyethylene and polypropylene can be preferably used. In particular, polypropylene can be preferably used in terms of elongation and tear strength.

  The breaking strength of the polyolefin film to be used is preferably 30 to 80 MPa, and more preferably 40 to 70 MPa. The elongation of the polyolefin film is preferably 300 to 800%, and more preferably 400 to 600%. The elastic modulus of the polyolefin film is preferably 100 to 1000 MPa, and more preferably 500 to 700 MPa. Each of the above physical properties is based on the measurement method defined in JIS K7127. When the above-mentioned physical properties of the polyolefin film are within the respective preferable ranges, it is particularly easy to exhibit a synergistic effect with the polyamide film layer.

  As for a support layer, it is preferable that a polyamide film layer is located in the surface layer side (surface opposite to the formation surface of an adhesive layer) with respect to a polyolefin film layer. By adopting such a positional relationship, the sheet float is remarkably reduced.

  In order to adjust physical properties such as strength and elongation, the support layer may be formed by laminating a plurality of the above-described or other unstretched plastic films. When laminating each layer, a general dry lamination adhesive can be used. By using multiple layers as described above, the poor tearability of the unstretched polyamide-based film is covered by the tearable strength of the unstretched polyolefin-based film, and good characteristics are obtained. Further, the unstretched polyamide-based film tends to absorb moisture and become wrinkles, but the unstretched polyolefin-based film does not absorb moisture, and thus has a side surface that can cover the disadvantages of the unstretched polyamide-based film as a whole.

  The elastic modulus of the entire support layer is preferably 100 to 1000 MPa, and more preferably 500 to 800 MPa. By setting the elastic modulus within this range, it is possible to more preferably prevent tearing and ironing. In particular, since the elastic modulus of the support layer is reduced, it becomes easier to follow the metal during processing during deep drawing. On the other hand, a support layer having a high elastic modulus has poor followability to deep drawing, and even if the breaking strength is high, the tearing strength is weak, so that the tape is easily broken so that the tape is torn in a horizontal line. The breaking strength of the entire support layer is preferably 40 to 200 N / 20 mm, and more preferably 50 to 90 N / 20 mm. By setting it as the breaking strength of the said range, the ironing tear of a sheet | seat can be prevented more preferably. The tear strength of the entire support layer is preferably 2 to 30N, and more preferably 5 to 10N. By setting the tear strength within the range, it is possible to more preferably prevent the sheet from tearing. When it is a support layer having a polyamide film layer and a polyolefin film layer, and the support layer has an elastic modulus, breaking strength and tear strength in the above ranges, it is possible to prevent tearing and ironing particularly remarkably. it can.

2. For the surface on the opposite side of the pressure-sensitive adhesive layer of the treatment agent surface protective pressure-sensitive adhesive sheet, it is preferable to use a conventionally known release agent such as silicone, long-chain alkyl, or fluorine.

3. Adhesive layer The adhesive layer is composed of an adhesive. The type of the pressure-sensitive adhesive is not particularly limited since a known pressure-sensitive adhesive can be used. For example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, Examples include polyether-based adhesives, polyamide-based adhesives, and fluorine-based adhesives. Moreover, the combination of the 1 type, or 2 or more types of adhesive selected from these adhesives may be sufficient. Moreover, the adhesive layer which concerns on this invention may contain the well-known additive. Although it does not specifically limit as an additive, For example, tackifying resin, a softener, antioxidant, a coloring agent, a filler, etc. are mentioned.

4). Primer Layer In the present invention, a primer layer can be provided between the support layer and the adhesive layer for the purpose of improving the anchoring force. Any primer layer can be used as long as it improves the anchoring force between the support layer and the adhesive layer and does not affect the adhesive properties of the adhesive layer.

  The thickness of each layer of the support layer can be arbitrarily set, but the total thickness including the support layer and the adhesive layer is preferably set as thin as possible. In particular, the thickness of each layer of the support layer is preferably 15 μm to 60 μm. Although there is no restriction | limiting in particular as the thickness of the said adhesion layer, Preferably it can use in the range of 1-15 micrometers. Further, the total thickness of the support layer and the adhesive layer is preferably 30 μm to 100 μm, and more preferably 31 μm to 100 μm.

  Hereinafter, the present invention will be specifically described with reference to examples. The present invention is not limited to these examples.

  Unstretched polyamide film (nylon 6 film (NY), Rayfan 1401 # 20 (20 μm), Toray) and unstretched polyolefin film (polypropylene film (CPP), Trefan No. 3501 # 20 (20 μm), Toray film) Processing) was dry laminated with an adhesive (Seika Bond E253, Dainichi Seika) to obtain a support layer of the present invention. Thereafter, a treatment agent was applied to the non-stretched polyolefin surface of the support layer, and a primer and a rubber-based pressure-sensitive adhesive 5 μm were applied to the non-stretched polyamide surface to obtain a surface protective pressure-sensitive adhesive sheet of the present invention. Detailed information on the polyolefin film used is shown in Table 1. In addition, each physical property of Table 1 is a value by the measuring method of JIS K7127 regulation.

  A surface protective pressure-sensitive adhesive tape according to Example 2 was obtained in the same manner as in Example 1 except that an unstretched polyolefin film (polypropylene film, Pyrene P1128, Toyobo) was used as the polyolefin film. Detailed information on the polyolefin film used is shown in Table 1.

  A surface protective pressure-sensitive adhesive tape according to Example 3 was obtained in the same manner as Example 1 except that an unstretched polyolefin film (polypropylene film, FHK2, Phthamura Chemical) was used as the polyolefin film. Detailed information on the polyolefin film used is shown in Table 1.

  A surface protective pressure-sensitive adhesive tape according to Example 4 was obtained in the same manner as in Example 3 except that the surface of the polyamide film was the front side and 5 μm of the rubber-based pressure-sensitive adhesive was applied on the surface of the polyolefin film.

(Comparative Example 1)
A treatment agent was applied to the surface of a support layer made of a polyethylene film (PE), and an acrylic pressure-sensitive adhesive 5 μm was applied on the opposite surface to obtain a surface protective pressure-sensitive adhesive sheet according to Comparative Example 1.

(Comparative Example 2)
Surface protection according to Comparative Example 2 in the same manner as in Example 1 except that a single layer of non-stretched polyamide film (nylon 6 film, Rayfan 1401 # 40 (40 μm), Toray film processing) was used as the support layer. An adhesive tape was obtained.

(Comparative Example 3)
The surface according to Comparative Example 3 is the same as Comparative Example 2, except that a single layer of unstretched polyolefin film (polypropylene film, Trefan No. 3501 # 40 (40 μm), Toray film processing) is used as the support layer. A protective adhesive tape was obtained.

(Comparative Example 4)
A surface protective pressure-sensitive adhesive tape according to Comparative Example 4 was obtained in the same manner as in Example 1 except that the polyolefin film constituting the support layer was a polyethylene terephthalate (PET) film.

(Comparative Example 5)
A surface protective adhesive tape according to Comparative Example 5 was obtained in the same manner as in Example 1 except that a stretched polyolefin film was used as the polyolefin film.

(Comparative Example 6)
A surface protective adhesive tape according to Comparative Example 6 was obtained in the same manner as in Example 1 except that a stretched polyamide film was used as the polyamide film.

(Test Example 1)
The surface protective adhesive sheets of Example 1 and Comparative Example 2 were attached to BASUS without wrinkles using a squeegee and then left at 40 ° C. and 75% RH for 1 week. Then, the state of the surface protective adhesive tape was visually observed. The results are summarized in Table 2.

(Test Example 2)
Deep drawing was performed using Examples 1 to 4 and Comparative Examples 1 to 6. The processed material is a metal plate having a thickness of 1.0 mm, and the material of the metal plate is BASUS304. A surface protective adhesive sheet was affixed to the SUS surface and the surface protective sheet was placed on the opposite side of the punch, and then deep drawing was performed. Deep drawing conditions were as follows: a cylinder having a punch inner diameter of 40 mm R2 mm and a die having a die inner diameter of 42.5 mm and R5 mm were used to deeply draw BASUS304 having a diameter of 80 mm circle with a die to obtain a cylinder having a depth of 30 mm. These results and other test results are summarized in Table 3.

  Tape tear was evaluated by calculating the area of the tape that was torn by deep drawing (◎: less than 5%, ○: 5% or more and less than 10%, Δ: 10% or more and less than 50%, ×: 50% or more ). At the same time, we observed how the tapes were torn and classified them into “tearing” and “scoring torn”. The method of tearing was defined as “tearing” when it was torn in a horizontal line, and “smashing was broken” when the tape was torn. The degree of floating of the tape was checked, and the floating area ratio was determined (：: 0% to less than 15%, ○: 15% to less than 30%, Δ: 30% to less than 45%, x: 45% or more).

(Measurement of breaking strength and elastic modulus)
The tensile test was performed according to JIS K 7127. The measurement sample was the MD direction, and used the surface protection sheet cut | disconnected in the shape of the test piece type 2 as described in JISK7127, and performed it with the chuck | zipper space | interval 50mm, test piece width 20mm, and the test speed 300mm / min. Further, an Instron type tensile tester (TENSILON RTM-100: Orientec Co., Ltd.) was used as the tester used for the measurement. The elastic modulus and breaking strength were obtained from a stress-strain curve, the elastic modulus was calculated from the initial slope, and the breaking strength was the strength when the surface protective sheet was broken.

(Measurement of tear strength)
The tear test was performed according to JIS K 7128-2. The measurement sample is in the TD direction, as shown in Fig. 3 described in JIS K 7128-2. Using a surface protective sheet cut into a rectangular test piece, measurement was performed in units of one sheet. Moreover, the test machine used for the measurement used the tear strength measuring apparatus (Elemendorf tear degree test machine: Kumagai Riki Kogyo Co., Ltd.). The tear strength was defined as the strength when 16 test pieces were stacked and the test length was 43 mm in the TD direction.

  In Comparative Example 1 and Comparative Example 3, tearing did not occur because the elastic modulus of the support layer was low and followability was good, but since the breaking strength was weak, the surface was rubbed and ironing was broken. In Comparative Example 2, since the support layer had a low elastic modulus, a high breaking strength, and a low tear strength, a horizontal line was torn. In the combination of the polyamide film of Comparative Example 4 and the polyethylene terephthalate film, tearing occurred. Moreover, as shown in Comparative Example 5 and Comparative Example 6, when a stretched film was used for one of the polyamide film and the polyolefin film, tearing occurred.

  In Examples 1 to 4, it was possible to prevent tearing and ironing by using a support layer that is a combination of an unstretched polyamide film and an unstretched polyolefin film. Among these, Example 4 in which the polyamide film is arranged on the surface layer side is particularly suitable, and it has been found that by using such a configuration, tearing of the tape is remarkably suppressed and floating is remarkably reduced.

Claims (5)

In a pressure-sensitive adhesive sheet having a support layer and a pressure-sensitive adhesive layer present on one surface thereof,
The support layer consists of at least two layers,
Each layer of the support layer is an unstretched plastic film,
A surface protective pressure-sensitive adhesive sheet for stamping and drawing, wherein the two layers are a polyamide film layer and a polyolefin film layer.   The surface protective pressure-sensitive adhesive sheet for stamping / drawing according to claim 1, wherein the polyamide film layer is made of an aliphatic polyamide resin.   The surface protection pressure sensitive adhesive sheet for stamping and drawing according to claim 1 or 2, wherein the polyolefin film layer is made of polypropylene resin.   The elastic modulus of the support layer is 500 to 800 MPa, the breaking strength of the support layer is 50 to 90 N / 20 mm, and the tear strength of the support layer is 5 to 10 N. A surface protective sheet for punching and drawing according to claim 1.   The surface protection for stamping and drawing according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer side of the support layer is a polyolefin film layer, and the surface layer side opposite to the pressure-sensitive adhesive layer is a polyamide film layer. Adhesive sheet.