JP2007144865A - Surface protecting film substrate, surface protecting adhesive film, and method for producing adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface protecting adhesive film which is good in processability, can suppress the occurrence of splitting, peeling, and a hit mark during processing, is low in adhesion, controls the occurrence of lifting, and good in peeling work properties, a method for producing the adhesive film, and a surface protecting film substrate used in the surface protecting adhesive film. <P>SOLUTION: The surface protecting film substrate (A) is made of a laminated film in which at least three layers are laminated. Both surface layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer held between both surface layers has at least one styrene-diene random copolymer layer (a2). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a film substrate for surface protection and an adhesive film for surface protection. The pressure-sensitive adhesive film for surface protection of the present invention can be applied for surface protection of various substances. In particular, it is useful as an adhesive film for protecting the surface of a metal plate such as a stainless steel plate, an aluminum plate, or a steel plate, and is suitable for protecting the surface during bending, roll forming, or drawing of the metal plate.

  Conventionally, when processing or transporting a metal plate such as a stainless steel plate, an aluminum plate, or a steel plate, a surface protective film is temporarily attached to prevent the surface of the metal plate from being scratched. We are trying to protect it. As a surface protective film for such a metal plate, an adhesive film having an adhesive layer provided on one side of a base film is used. As a base material of such an adhesive film, for example, a film obtained by mixing polyethylene and polypropylene (see, for example, Patent Document 1), or two or more kinds of polyethylene, polypropylene, and ethylene-propylene copolymer are mixed at a specific mixing ratio. (For example, see Patent Document 2).

  However, when the metal plate is processed such as deep drawing or bending, the surface-protective adhesive film cannot follow the plastic deformation of the metal plate, and a part thereof may be peeled off or torn. In particular, in the manufacture of a deep bottom that cannot be produced by a single deep drawing, such as a sink part (a sink tank) of a sink, it is necessary to perform further redrawing after the first deep drawing. In this case, if the surface protective adhesive film is peeled off or torn at the first deep drawing, there is a problem that the next redrawing makes a dent on the surface of the metal plate and impairs the commercial value.

  If the pressure-sensitive adhesive film for surface protection is strengthened, the peeling and tearing of the pressure-sensitive adhesive film can be eliminated. However, when the adhesive strength is increased, there arises a problem that it is difficult to remove the adhesive film for surface protection. Therefore, it is necessary to eliminate peeling and tearing of the surface protective film without increasing the adhesive strength.

  For the above problem, as the base film of the adhesive film for surface protection, a laminated film in which both outermost layers are crystalline polyolefin layers and an amorphous polyolefin layer is laminated on an intermediate layer sandwiched between both outermost layers Have been proposed (see, for example, Patent Documents 3 and 4). The adhesive film for surface protection using these laminated films does not peel off or tear during processing. However, in the proposal of Patent Document 3, since the amorphous polyolefin used for the intermediate layer contains a large amount of resin gel, the resin gel may be mixed into the film formed (laminated film). It was found that when the resin gel is present on the film and the metal plate is laminated and pressed, a dent may be formed on the surface of the metal plate as described above. On the other hand, according to the proposal of Patent Document 4, it has been found that depending on the type and use of the metal plate, an increase in adhesive force may be caused, which may make it difficult to peel off or the tape application part may float.

Japanese Patent Publication No.59-27782 Japanese Patent Publication No. 50-14667 Japanese Patent Laid-Open No. 10-110145 JP 2004-189972 A

  Therefore, the present invention has good workability even when used as an adhesive film for protecting the surface of a metal plate in order to cope with the above-mentioned problems, and can suppress the generation of tears, peeling, and dents during processing. An object of the present invention is to provide a surface-protective pressure-sensitive adhesive film that has a low adhesive force, suppresses the occurrence of floating, and has good peeling workability, and a method for producing the same.

  Moreover, an object of this invention is to provide the film base material for surface protection used for the said adhesive film for surface protection.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using the following surface protective pressure-sensitive adhesive film and surface protective film substrate, and to complete the present invention. It came.

That is, the film substrate for surface protection of the present invention is
A film substrate for surface protection comprising a laminated film in which at least three layers are laminated, wherein both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers Has at least one styrene-diene random copolymer layer (a2).

  Since the film base material for surface protection of the said invention has the said structure, it can suppress the residual stress when deform | transforming small. Moreover, since the said styrene-diene random copolymer layer (a2) has few resin gels and generation | occurrence | production of a dent is suppressed, generation | occurrence | production of inferior goods is suppressed. Therefore, especially when used as an adhesive film for surface protection, it is possible to suppress peeling, tearing, floating, etc. of the adhesive film during processing of the object to be protected without increasing the adhesive strength of the adhesive layer, and further peeling work The processability is also good, so the processability is excellent.

  In the surface protective film substrate, the styrene-diene random copolymer layer (a2) is preferably a hydrogenated layer of styrene-butadiene random copolymer.

  On the other hand, the surface-protective pressure-sensitive adhesive film of the present invention is characterized by having a pressure-sensitive adhesive layer on one surface of any one of the above-mentioned surface-protective film base materials. Since the surface protective adhesive film of the present invention includes the surface protective film substrate having the above-described effects, it has good workability, can suppress the occurrence of tearing, peeling, and dents during processing, and has low adhesive strength. In this case, the occurrence of floating is suppressed, and the peeling workability is improved.

  Moreover, in the said surface protection adhesive film, it is preferable that the said film base material and the said adhesive layer are integrally formed by coextrusion molding.

Furthermore, it is preferable that the surface protective adhesive film has a residual stress of 6 N / mm ² or less when the deformation amount is 10%.

On the other hand, the method for producing a surface protective pressure-sensitive adhesive film of the present invention is a method for producing a surface protective pressure-sensitive adhesive film comprising a step of integrally forming a film substrate and a pressure-sensitive adhesive layer by coextrusion molding,
The film substrate is composed of a laminated film in which at least three layers are laminated, both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers is styrene- It has at least one diene random copolymer layer (a2).

  By using the production method of the present invention, the processability is good even when used as an adhesive film for protecting the surface of a metal plate, and the occurrence of tearing, peeling, and dents during processing can be suppressed. It is possible to obtain a surface-protective pressure-sensitive adhesive film that suppresses the occurrence of floating due to the adhesive force and has good peeling workability.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the film substrate for surface protection of the present invention (hereinafter sometimes referred to as a substrate film)
A film substrate for surface protection comprising a laminated film in which at least three layers are laminated, wherein both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers Has at least one styrene-diene random copolymer layer (a2).

  The surface protective film substrate (A) of the present invention (hereinafter sometimes referred to as a substrate film (A)) is a laminated film having at least three layers as shown in FIG. Both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers has at least one styrene-diene random copolymer layer (a2).

  FIG. 1 shows an example in which one styrene-diene random copolymer layer (a2) is provided as an intermediate layer. The intermediate layer only needs to have at least one styrene-diene random copolymer layer (a2). Therefore, for example, the intermediate layer may be a plurality of layers of a styrene-diene random copolymer layer (a2) or a plurality of layers of a styrene-diene random copolymer layer (a2) and a crystalline polyolefin layer (a1). There may be.

  In the base film (A), the resin that forms the outermost crystalline polyolefin resin layer (a1) is a polyolefin having at least a portion exhibiting crystallinity, and examples thereof include crystalline polypropylene and polyethylene. .

  Examples of the crystalline polyolefin include those having a syndiotactic structure, an isotactic structure, and the like. Since polyethylene usually exhibits crystallinity, the type of polyethylene is not particularly limited, but low-pressure polyethylene is preferred. These crystalline polyolefins can be used alone or in combination of two or more.

  As the crystalline polyolefin, those containing crystalline polypropylene are preferable because of good adhesion to the intermediate layer of the styrene-diene random copolymer layer (a2). In the case where crystalline polypropylene and other crystalline polyolefin are used in combination, the content of crystalline polypropylene in the styrene-diene random copolymer layer (a2) as the intermediate layer is preferably 30% by weight or more, preferably It is desirable that it is 50 weight% or more. When the content of polypropylene is 30% by weight or more, the adhesion between the outermost layer and the intermediate layer is good, and delamination between layers is unlikely to occur.

  The styrene-diene random copolymer layer (a2) used for the intermediate layer is particularly preferably a hydrogenated layer of styrene-butadiene random copolymer. Assuming that the surface protection tape is applied outdoors for a long period of time, weather resistance is required, but the hydrogenated styrene-butadiene random copolymer has a higher molecular weight than the non-hydrogenated styrene-butadiene random copolymer. This is because the structure is difficult to cut and is assumed to be stable.

  The proportion of butadiene units in the hydrogenated styrene-butadiene random copolymer is preferably 30 to 99% by weight, more preferably 50 to 97% by weight. The butadiene unit in the copolymer chain preferably has at least 25% by weight of 1,2-bond. By using a butadiene unit of 30% by weight or more or a 1,2-bond of 25% by weight or more, rubber elasticity is hardly lowered.

  Moreover, it is preferable that the hydrogenated layer of the styrene-diene random copolymer is present in a state of good compatibility, that is, the hydrogenated material is uniformly dispersed in the layer. This is because the tearability and stress relaxation properties of the base film are improved, which is more preferable in terms of workability and peelability.

  In addition to the styrene-diene random copolymer layer, the intermediate layer may include other layers such as a polyolefin layer.

  For the formation material of the base film (A) such as the outermost crystalline polyolefin resin layer (a1) and the styrene-diene random copolymer layer (a2) used for the intermediate layer, titanium oxide is optionally used. Inorganic fillers such as zinc oxide and calcium carbonate, amine-based, quinoline-based, hydroquinone-based, phenol-based and phosphite-based antioxidants and antioxidants, salicylic acid derivatives, benzophenone-based, benzotriazole-based, hindered amines You may mix | blend 1 type (s) or 2 or more types, such as ultraviolet absorbers, lubricants, plasticizers, etc., as long as the object of the present invention is not impaired.

  Moreover, although the thickness of the crystalline polyolefin layer (a1) of both outermost layers may be the same or different, it is preferable to be comprised by the same thickness. When the outermost layer on the front side and the outermost layer on the pressure-sensitive adhesive layer side have the same thickness, curling is unlikely to occur on the film substrate (and the pressure-sensitive adhesive film), and the workability of bonding to a metal plate is reduced. This is because it is difficult to do.

  The thickness of the base film (A) is usually preferably about 30 to 200 μm and more preferably about 50 to 150 μm from the viewpoint of processability. That is, it is appropriate that the adhesive film for surface protection using the film base material has a thickness of about 30 μm or more in order to maintain an appropriate strength during processing, and a thickness to make the residual stress appropriate. It is appropriate that the thickness is about 200 μm or less.

  Further, the thickness of the intermediate layer is 50 to 98%, preferably 60 to 90% of the thickness of the base film. By controlling the thickness of the intermediate layer within the above range, the workability of the base film can be maintained at a good level.

  Even when the intermediate layer is formed of a plurality of layers, the thickness of the intermediate layer is preferably adjusted within the above range. However, even when the intermediate layer is formed of a plurality of layers, a styrene-diene random copolymer is used. The polymer layer (a2) preferably has at least 50% of the thickness of the base film.

  The surface protective film substrate of the present invention has the above-described configuration.

  On the other hand, the pressure-sensitive adhesive film for surface protection of the present invention is characterized by having a pressure-sensitive adhesive layer (B) on one surface of any one of the above-mentioned surface protective film base materials (A).

  The adhesive film for surface protection of this invention has an adhesive layer (B) on the single side | surface of a base film (A), for example, as shown in FIG. The base film (A) is a laminated film in which at least three polyolefin layers are laminated. Both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers has at least one styrene-diene random copolymer layer (a2). In addition, the adhesive film for surface protection of this invention can be used with a sheet form, tape shape, etc.

  On the other hand, the production method of the base film (A) having the intermediate layer having the styrene-diene random copolymer layer (a2) and the outermost layer being the crystalline polyolefin resin layer (a1) is not particularly limited. The method can be adopted. For example, a method of melt-coextrusion of the resin material constituting each layer to form into a laminate, a method of individually forming each layer into a film by extrusion or the like, and bonding them with an adhesive or the like are exemplified. Among these methods, the method by coextrusion molding and melt coextrusion molding is preferable from the viewpoint of good adhesion between the respective layers and simplifying the process.

  The base film (A) has an adhesive layer (B). As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer (B), various pressure-sensitive adhesives used in the field of the surface protective pressure-sensitive adhesive film such as an acrylic pressure-sensitive adhesive and a rubber-based pressure-sensitive adhesive can be used. The thickness of the pressure-sensitive adhesive layer is usually preferably about 1 to 100 μm, more preferably about 1 to 20 μm. The adhesive strength of the pressure-sensitive adhesive layer is suitably about 0.2 to 3.0 N / 20 mm. The adhesive strength of the pressure-sensitive adhesive layer was obtained by measurement under conditions of a temperature of 23 ° C., a tensile speed of 300 mm / min, and 180 ° peeling.

  The above-mentioned pressure-sensitive adhesive may contain other known additives, for example, cross-linking agents such as isocyanate compounds, silane coupling agents, tackifiers, colorants, pigments and other powders, dyes, interfaces Activator, plasticizer, surface lubricant, leveling agent, softener, antioxidant, anti-aging agent, light stabilizer, UV absorber, polymerization inhibitor, inorganic or organic filler, metal powder, particulate, foil It can be added as appropriate depending on the intended use of the product. Moreover, you may employ | adopt the redox system which added a reducing agent within the controllable range.

  The surface of the pressure-sensitive adhesive layer may be subjected to easy attachment treatment such as corona treatment or plasma treatment.

  Furthermore, when the pressure-sensitive adhesive layer is exposed on such a surface, the pressure-sensitive adhesive layer may be protected with a release sheet (separator, release film) that has been subjected to a release treatment until practical use.

  As a constituent material of the separator, for example, a plastic film such as polyethylene, polypropylene, polyethylene terephthalate, and a polyester film, a porous material such as paper, cloth, and nonwoven fabric, a net, a foamed sheet, a metal foil, and a laminate thereof, as appropriate. A thin film can be used, but a plastic film is preferably used because of its excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm.

  For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to perform antistatic treatment such as. In particular, when the surface of the separator is appropriately subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, the peelability from the pressure-sensitive adhesive layer can be further improved.

  In the above production method, the release-treated sheet can be used as it is as a separator such as a surface protecting adhesive film, and the process can be simplified.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. The evaluation items in the examples and the like were performed as follows.

[Example 1]
As a resin constituting the intermediate layer, an SOE elastomer (trade name: SOESE L601, manufactured by Asahi Kasei Co., Ltd.), which is a hydrogenated product of a styrene-butadiene random copolymer, was used. As the resin constituting the outermost layer, homopolypropylene (crystalline, trade name: F-704NP, manufactured by Idemitsu Petrochemical Co., Ltd.) was used.

  These resin materials are formed into a film by melt coextrusion (extruder temperature in a single screw extruder, resin is melted at a die temperature of 200 ° C.), and the outermost layer / intermediate layer / outermost layer has a thickness of 7 μm / each. A three-layer laminated film having a thickness of 26 μm / 7 μm was obtained. The surface (outermost layer) of this laminated film was subjected to corona treatment. Subsequently, this laminated film was used as a base film.

  The outermost layer is an acrylic adhesive layer having a dry thickness of 5 μm (25% by weight acrylic ester consisting of butyl acrylate (80 mol), acrylic acid (10 mol), and methyl methacrylate (10 mol) in ethyl acetate). A copolymer is prepared, and 5 parts by weight of a crosslinking agent (polyisocyanate, trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) is added to 100 parts by weight (solid content) of this solution to prepare a pressure-sensitive adhesive composition. The phosphoric acid ester-based surfactant (trade name: GAFAC-RL-210, manufactured by Toho Chemical Co., Ltd.) 0.3 parts by weight is added to 100 parts by weight (solid content) of the pressure-sensitive adhesive composition. It provided and obtained the adhesive film for surface protection.

[Example 2]
As a resin constituting the intermediate layer, homopolypropylene (crystals) with respect to 100 parts by weight of an SOE elastomer (trade name: SOESE L601, manufactured by Asahi Kasei Co., Ltd.), which is a hydrogenated product of a styrene-butadiene random copolymer. Properties, trade name: F-704NP, manufactured by Idemitsu Petrochemical Co., Ltd. 30 parts by weight, and rubber-based pressure-sensitive adhesive (polyisobutylene (trade name: Vistanex MML-100, Exxon PIB) as the pressure-sensitive adhesive layer) A surface-protective pressure-sensitive adhesive film was obtained in the same manner as in Example 1 except that 100 parts by weight and a tackifier resin (trade name: ester gum H, TF manufactured by Arakawa Kogyo Co., Ltd.) were used.

Example 3
As a resin constituting the intermediate layer, an SOE elastomer (trade name: SOESE L601, manufactured by Asahi Kasei Co., Ltd.), which is a hydrogenated product of a styrene-butadiene random copolymer, was used.

  Homopolypropylene (crystalline, trade name: F-704NP, manufactured by Idemitsu Petrochemical Co., Ltd.) was used as the outermost layer.

  The pressure-sensitive adhesive layer is composed of 100 parts by weight of a rubber-based SEBS elastomer (trade name: KRATON G 1657, manufactured by KRATON) and 30 parts by weight of a tackifier resin (trade name: Alcon P-125, manufactured by Arakawa Industrial Co., Ltd.). It was.

  Film formation of these resin materials by melt coextrusion (extruder temperature in a single screw extruder, resin melted at a die temperature of 200 ° C.), the outermost layer / intermediate layer / outermost layer / adhesive layer is Four-layer surface-protective pressure-sensitive adhesive films each having a thickness of 7 μm / 26 μm / 7 μm / 5 mm were obtained.

[Comparative Example 1]
In Example 1, SEBS elastomer (trade name: Dynalon 8600P, manufactured by JSR) was used as the intermediate layer of the base film, and the thickness after drying of the pressure-sensitive adhesive layer was 7 μm. In the same manner as above, an adhesive film for surface protection was obtained.

[Comparative Example 2]
In Example 1, Example 1 except that SEPS elastomer (trade name: Septon 2063, manufactured by Clera Co., Ltd.) was used as the intermediate layer of the base film, and that the thickness of the pressure-sensitive adhesive layer after drying was 7 μm. In the same manner as above, an adhesive film for surface protection was obtained.

[Comparative Example 3]
In Example 1, the same as Example 1 except that LDPE (trade name: Novatec LD LF440C, manufactured by Nippon Polyethylene Co., Ltd.) was used as the base film, and the thickness of the pressure-sensitive adhesive layer after drying was 7 μm. Thus, an adhesive film for surface protection was obtained.

[Comparative Example 4]
In Example 1, PP (trade name: Novatec PP BC3F, manufactured by Nippon Polypropylene) was used as the base film, and the thickness after drying of the pressure-sensitive adhesive layer was 7 μm. Thus, an adhesive film for surface protection was obtained.

[Comparative Example 5]
In Example 1, except that an SOE elastomer (trade name: SOESE-SS L601, manufactured by Asahi Kasei Co., Ltd.) was used as the base film, and the thickness of the pressure-sensitive adhesive layer after drying was 7 μm. A pressure-sensitive adhesive film for surface protection was obtained in the same manner as Example 1.

[Comparative Example 6]
In Example 1, a resin (trade name: KS-021P, manufactured by Sun Allomer Co., Ltd.) having 100 parts by weight of a hard segment made of polypropylene and 80 parts by weight of a soft segment made of ethylene-propylene rubber as an intermediate layer of the base film. A surface protecting adhesive film was obtained in the same manner as in Example 2 except that it was used.

[Comparative Example 7]
A surface protective adhesive film was obtained in the same manner as in Example 1 except that the same three-layer base film as in Comparative Example 6 was used.

  The following evaluation was performed about the adhesive film for surface protection obtained by the Example and the comparative example. The results are shown in Table 1.

(Measurement of residual stress)
In order to measure the residual stress, a test piece (width 20 mm, length 100 mm) was produced from the surface protective adhesive film. This is done by setting the chuck between 50 mm, stretching at a speed of 300 mm / min until the deformation amount of the test piece becomes 10%, and then leaving it for 5 minutes to measure the stress generated on the test piece. It was. The measurement ambient temperature was 23 ° C.

(Processability evaluation)
A test piece (100 mmφ) was prepared from the adhesive film for surface protection. This was affixed to a stainless steel plate (SUS304BA, 0.4 mm thickness), and a 40 mm square cylinder drawing and a drawing depth of 20 mm were drawn using a press machine (60 t press machine manufactured by AIDA). At that time, the occurrence of tearing, floating (peeling), and dents in the film was examined. Those that did not occur were indicated as “◯”, and those that occurred were indicated as “X”.

(Evaluation of peeling workability)
After completion of the above processing, the surface protecting adhesive film was peeled off from the stainless steel plate, and the peeling workability was evaluated. The evaluation of peeling workability was carried out for two items: whether the adhesive film was not torn at the time of peeling (tearability), and whether the film was stretched more than necessary and the work became difficult (workability). If the peeling workability did not decrease due to this, “◯” was indicated, and if the peeling workability deteriorated, “x” was indicated.

(Measurement of adhesive strength)
The adhesive strength was measured using a stainless steel plate (manufactured by Nippon Metal Industry Co., Ltd., product name: SVS 430BA) as an adherend.

  Specifically, it was pressure-bonded to the adherend using a 2 kg roller, and after 30 minutes, it was measured by Instron (manufactured by Shimadzu Corporation, Autograph) under the conditions of a tensile speed of 300 mm / min and 180 ° peel. The measurement environment and storage environment were 23 ° C./50% RH.

(Evaluation of bonding workability)
When the adhesive film for surface protection was bonded to a stainless steel plate (SUS304BA, 0.4 mm thickness) with a hand roller, it was evaluated whether or not the film was curled. If no curling occurs, “◯” is indicated, and if curling occurs, “×” is indicated.

  As can be seen from Table 1, the surface-protective adhesive films prepared in Examples 1 to 3 have low residual stress, suppress the occurrence of floating with low adhesive force, and workability, peeling workability, and bonding work It is recognized that the property is also good.

It is one aspect | mode of sectional drawing of the adhesive film for surface protections of this invention.

Explanation of symbols

A: Film base material B: Adhesive layer a1: Outermost crystalline polyolefin layer a2: Styrene-diene random copolymer layer as an intermediate layer

Claims (8)

  A film substrate for surface protection comprising a laminated film in which at least three layers are laminated, wherein both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers Has at least one styrene-diene random copolymer layer (a2).   The film substrate for surface protection according to claim 1, wherein the styrene-diene random copolymer layer (a2) is a hydrogenated layer of styrene-butadiene random copolymer.   A pressure-sensitive adhesive film for surface protection, comprising a pressure-sensitive adhesive layer on one side of the film substrate for surface protection according to claim 1 or 2.   The surface protective pressure-sensitive adhesive film according to claim 3, wherein the film base material and the pressure-sensitive adhesive layer are integrally formed by coextrusion molding. The surface-protective pressure-sensitive adhesive film according to claim 3 or 4, wherein the surface-protective pressure-sensitive adhesive film has a residual stress of 6 N / mm ² or less when the deformation amount is 10%. A method for producing an adhesive film for surface protection comprising a step of integrally forming a film substrate and an adhesive layer by coextrusion molding,
The film substrate is composed of a laminated film in which at least three layers are laminated, both outermost layers of the laminated film are crystalline polyolefin layers (a1), and an intermediate layer sandwiched between both outermost layers is styrene- A method for producing an adhesive film for surface protection, comprising at least one diene random copolymer layer (a2).   The method for producing a surface protective adhesive film according to claim 6, wherein the styrene-diene random copolymer layer (a2) is a hydrogenated layer of styrene-butadiene random copolymer. The surface protective pressure-sensitive adhesive film according to claim 6 or 7, wherein the surface protective pressure-sensitive adhesive film has a residual stress of 6 N / mm ² or less when the deformation amount is 10%. Production method.

Images