JP2008255150A - Resin composition and surface-protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-protective film produced in a method, without impairing the advantages of a co-extrusion process enabling a film to be produced in high productivity and at low cost, for example, even if an adhesive layer is stuck onto the back surface of a substrate, enabling the adhesive layer to be readily peeled thereoff, thus enabling a film roll to be rewound smoothly, and capable of maximally preventing the staining of a cooling roll for cooling the back surface side of a substrate in continuous film production. <P>SOLUTION: A first resin composition is provided, comprising 100 pts.wt. of a polar bond-bearing thermoplastic silicone elastomer and 10-700 pts.wt. of an acid-modified polyolefin. A second resin composition is provided, being such as to be formed by compounding 100 pts.wt. of a polyolefin resin with 0.5-50 pts.wt. of the first resin composition. The surface-protective film comprises a substrate and an adhesive layer, wherein the substrate has a layer formed of the latter resin composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin composition and a surface protective film, and more particularly to a resin composition and a surface protective film used for preventing adhesion of dust to the surface of the adherend and scratching of the surface of the adherend.

  Conventionally, for example, when various articles and members such as optical devices, metal plates, painted steel plates, resin plates, glass plates, etc. are transported, processed, or cured, dirt adheres to these surfaces or the surface is damaged. A surface protective film is used to prevent this.

This type of surface protective film has a structure in which an adhesive layer is laminated on a substrate. The surface protective film is manufactured, for example, by applying a pressure-sensitive adhesive solution containing an elastomer or the like to a base material made of a synthetic resin or the like, or coextruding the base material and the pressure-sensitive adhesive layer. The method of co-extrusion of the base material and the pressure-sensitive adhesive layer is advantageous because the productivity is high and the manufacturing cost can be reduced.
Moreover, such a surface protection film is industrially manufactured as a wound body which wound the elongate film in roll shape, for example. In the surface protective film as such a wound body, when the wound body is unfolded, the outer surface protective film can be easily peeled off from the inner surface protective film, that is, the wound body is unwound. There is a strong demand for being easy.

  As a surface protective film obtained by coextrusion, a surface protective film in which a base material made of polyethylene having a polyorganosiloxane as a graft chain and an adhesive layer are laminated is disclosed (for example, Patent Document 1). Patent Document 1 also shows a configuration in which an intermediate layer made of a polyolefin-based resin is provided between a base material and an adhesive layer. It is said that the wound body can be well rewound after a lapse of time by forming the base material using polyethylene having a polyorganosiloxane as a graft chain.

  By the way, the surface protective film is roughly classified into a low-adhesion type having a relatively low adhesive strength to an adherend and a high-adhesion type having a relatively large adhesive strength. In particular, in the latter highly adhesive type surface protective film, a release treatment is performed on the back surface of the base material in order to improve the rewinding property of the wound body.

  As the surface protection film subjected to the mold release treatment, the base material made of polyolefin resin and the pressure-sensitive adhesive layer are laminated, and the back surface of the base material (opposite side to the pressure-sensitive adhesive layer lamination side of the base material, hereinafter the same) is solid. An adhesive tape that has been subjected to a friction treatment is disclosed (for example, Patent Document 2).

On the other hand, after a base material containing a polyolefin resin and a pressure-sensitive adhesive layer containing a thermoplastic elastomer are laminated and formed by a coextrusion method, a release layer made of a release agent is applied to the back surface of the base material. A surface protective sheet formed by a construction method is disclosed (for example, Patent Document 3).
Japanese Patent Laid-Open No. 2-252782 JP-A-2-252777 JP 2003-41216 A

In Patent Document 3, a release layer is formed on the back surface of the base material. However, in order to form the release layer, it is necessary to perform steps such as application of a release agent, drying, and curing. When these steps are performed, there is a problem that productivity is lowered and manufacturing costs are increased. Furthermore, particularly when a uniform release layer is formed, the application rate of the release agent has to be slowed down, and the surface protective film cannot be produced efficiently.
In Patent Document 2, the back surface of the base material is friction-treated with a solid, and this friction treatment can be performed in a relatively simple manner in-line. However, the friction treatment cannot sufficiently improve the rewinding property of the wound body. Moreover, the improvement effect of the rewinding property by friction treatment varied depending on the selection of the polyolefin resin constituting the substrate.

  In Patent Document 1, as described in Patent Documents 2 and 3, there is no need to friction-treat the back surface of the base material with a solid or to form a release layer by coating on the back surface of the base material. And a surface protection film can be manufactured at low cost. However, in the invention described in Patent Document 1, during storage in a wound body, unreacted polyorganosiloxane present in the raw material migrates from the substrate surface to the adhesive surface, resulting in a problem that the adhesive strength decreases. there were.

  In order to solve the above problems, the present inventors have already proposed a surface protective film using a specific silicone elastomer as a base resin (Japanese Patent Application No. 2006-262563), and obtained satisfactory results. Yes. However, if this surface protective film is produced continuously for a long time, a slight amount of bleed-out component gradually accumulates on the cooling roll that cools the back side of the substrate, which causes defects such as dents on the film surface. At the same time, it has led to a new problem of increasing the cleaning frequency of the roll.

  The object of the present invention is to solve the advantages of the coextrusion method that can be produced with high productivity and low cost in view of the current state of the prior art described above, for example, even if the adhesive layer is adhered to the back surface of the substrate. The pressure-sensitive adhesive layer can be easily peeled off from the back surface of the base material, and the wound body can be unwound easily, and the adhesive force due to the transition from the release layer to the adhesive surface during storage in the wound body It is possible to provide a surface protective film that can suppress the decrease in the temperature and prevent contamination of the cooling roll that cools the back side of the substrate during continuous production as much as possible.

As a result of intensive studies on the above-mentioned problems and existing surface protective films, the present inventors have arbitrarily mixed other polyolefins and other resins with a mixture of a specific silicone elastomer and a specific polyolefin. It has been found that the above problems can be solved by forming the surface layer of the material layer, and the present invention has been completed.
The first resin composition of the present invention comprises 100 parts by weight of a thermoplastic silicone elastomer having a polar bond and 10 to 700 parts by weight of an acid-modified polyolefin.
The second resin composition is characterized in that 0.5 to 50 parts by weight of the resin composition according to claim 1 is blended with respect to 100 parts by weight of the polyolefin resin.
Furthermore, the surface protective film of the present invention is a surface protective film comprising a substrate and a pressure-sensitive adhesive layer, and the substrate is released from the resin composition on the surface opposite to the pressure-sensitive adhesive layer of the substrate. It has a layer.
In this surface protective film, it is preferable that the pressure-sensitive adhesive layer has a thermoplastic elastomer as a main component and is formed by coextrusion.

  The resin composition of the present invention and the surface protective film using the same are used for a pressure-sensitive adhesive layer containing a thermoplastic elastomer as a main component without losing the advantages of a co-extrusion method that can be produced with high productivity and low cost. In particular, while having high releasability, there is little migration of contaminants from the release layer to the adhesive surface during storage in a wound body, and it is possible to suppress a decrease in adhesive strength during storage. Furthermore, it is possible to suppress the adhesion of a cooling roll stain that cools the back side of the substrate during melt extrusion molding, particularly during continuous production, and to provide a surface protective film with better quality, By reducing the cleaning frequency, the manufacturing cost can be further reduced and an inexpensive surface protective film can be provided.

The first resin composition of the present invention contains a specific silicone elastomer and an acid-modified polyolefin.
The silicone elastomer is a thermoplastic silicone elastomer having a polar bond, and includes, for example, a block polymer in which a polyorganosiloxane that is a soft segment forms a polar bond with a functional group of an organic molecule constituting a hard segment. . Here, examples of the polar bond include a urea bond, a urethane bond, an amide bond, and an ester bond.
Examples of the polyorganosiloxane include polydimethylsiloxane, polymethylpropylsiloxane, polydipropylsiloxane, polymethyloctylsiloxane, polydioctylsiloxane, polymethylphenylsiloxane, and polydiphenylsiloxane. These may be used alone or in combination of two or more.

The acid-modified polyolefin means a polyolefin into which a carboxyl group or an acid anhydride group has been introduced. Examples of the acid-modified polyolefin include a method of graft-modifying an unsaturated carboxylic acid or an anhydride thereof to the polyolefin, a method of copolymerizing an α-olefin with an unsaturated carboxylic acid or an anhydride thereof, and the like.
Although it does not restrict | limit especially as polyolefin, For example, propylene-type polymers, such as a block system which consists of a homo polypropylene or a propylene component, and an ethylene component, a random type; Ethylene-type polymers, such as a low density, a high density, a linear low density polyethylene; Ethylene-alpha Examples thereof include olefin polymers such as olefin copolymers, olefin polymers of ethylene components and other monomers such as ethylene-vinyl acetate copolymers and ethylene-methyl methacrylate copolymers. These polyolefins may be used alone or in combination of two or more.

Examples of the unsaturated carboxylic acid or anhydride thereof include acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, and the like, and anhydrides thereof. Of these, maleic anhydride is preferred.
In particular, maleic anhydride-modified polyolefin is preferable as the acid-modified polyolefin. The maleic anhydride-modified polyolefin is a polyolefin copolymer in which a skeleton of maleic anhydride is introduced into the molecule. Examples of maleic anhydride modified polyolefin include maleic anhydride graft modified polyethylene, maleic anhydride graft modified polypropylene, maleic anhydride graft modified ethylene-propylene copolymer, maleic anhydride graft modified ethylene-ethyl acrylate copolymer, maleic anhydride. Examples include graft-modified ethylene-vinyl acetate copolymer, maleic anhydride-α-olefin copolymer polyethylene, and these may be used alone or in combination of two or more. By using the acid-modified polyolefin, contamination of the cooling roll due to the bleed-out of the silicone elastomer can be prevented. The reason for this is not clear, but it is thought that the increased interaction between the polar bond portion of the silicone elastomer and the modifying group in the acid-modified polymer is related. Further, in order to form a surface protective film using the resin composition of the present invention, as described later, when a layer made of an unmodified polyolefin is included as a base material or an intermediate layer, an anchor for the unmodified polyolefin is used. The force (anchor force) can be increased, and sufficient interlayer strength can be ensured.

The blending ratio of the acid-modified polyolefin to 100 parts by weight of the thermoplastic silicone elastomer having a polar bond is preferably 10 to 150 parts by weight, more preferably 20 to 100 parts by weight, and still more preferably 30 to 90 parts by weight. By setting these ratios, it is possible to ensure appropriate releasability and to obtain the effect of preventing the cooling roll stain during molding. Moreover, when the surface protection film of this invention contains the layer which consists of polyolefin as a base material or an intermediate | middle layer, the anchoring force with respect to polyolefin can be raised and sufficient interlayer strength can be ensured.
In addition, the 1st resin composition may contain other resin (for example, polyolefin etc.) other than specific silicone elastomer and acid-modified polyolefin in the range which does not inhibit achievement of the subject of this invention.

Moreover, the 2nd resin composition of this invention is a resin composition which mix | blended polyolefin resin and the 1st resin composition mentioned above.
The same polyolefin resin as described above can be used.
0.5-50 weight part is preferable, as for the mixture ratio of the 1st resin composition with respect to 100 weight part of polyolefin, 0.7-30 weight part is more preferable, and 1-20 weight part is further more preferable. By setting these ratios, it is possible to maintain appropriate releasability and further ensure the effect of preventing contamination of the cooling roll during molding. Moreover, when the surface protection film of this invention contains the layer which consists of polyolefin as a base material or an intermediate | middle layer, the anchoring force with respect to polyolefin can be raised and sufficient interlayer strength can be ensured.
The second resin composition may contain other resins (for example, polyolefin, etc.) in addition to the polyolefin resin and the first resin composition, as long as the object of the present invention is not impaired. .

  In the first and second resin compositions described above, other additives may be used as necessary within a range not impeding the achievement of the object of the present invention. Examples of such additives include known light stabilizers such as ultraviolet absorbers, antioxidants, hindered amine light stabilizers, and antistatic agents. Furthermore, for example, known materials such as fillers such as calcium oxide, magnesium oxide, silica, zinc oxide, and titanium oxide, pigments, anti-scratch agents, lubricants, and anti-blocking agents can be appropriately blended as additives. .

  The surface protective film of this invention is comprised from a base material and an adhesive layer at least. The substrate may be a single layer or multiple layers, but it has a multilayer structure comprising a surface layer having a release function and an intermediate layer having an interlayer adhesion function between both the surface layer and the pressure-sensitive adhesive layer. Is preferred. In addition, as for a base material, in any case of a single layer and a multilayer, about 10-200 micrometers is suitable for a total film thickness, 20-150 micrometers, Furthermore, 30-100 micrometers is more preferable.

  In one embodiment, the base material is preferably formed of the above-described second resin composition. In this case, a layer having a release function can be formed by blending a specific silicone elastomer and an acid-modified polyolefin as in the second resin composition. In addition, by further blending a polyolefin resin, it is possible to adjust the releasability and moldability, and the material cost for forming the layer is suppressed, which is advantageous in terms of cost. As a result, on the back surface of the base material, the surface protective film formed as a roll wound in a roll shape can be easily and easily formed without causing adhesive residue without providing a separate surface layer having a release function. Can be rewound.

In another embodiment, it is preferable that a release layer formed of the first or second resin composition described above is disposed on the back surface of the substrate. In this case, the substrate may have a function only of the original formability of the substrate, but it is preferable that the substrate itself functions as an anchor layer (intermediate layer).
Here, the thickness of the release layer is not particularly limited, but about 0.5 to 50 μm is suitable, preferably 1 to 30 μm, and more preferably 2 to 10 μm. Moreover, the thickness of the base material here is not particularly limited, but may be adjusted so as to be within the above-mentioned range as the total thickness combined with the release layer.

The base material layer may be formed of any material as long as it functions as an anchor layer between the release layer and the pressure-sensitive adhesive layer. For example, it is preferable to select a material that can be extruded. . Especially, it is preferable to form with polyolefin. Although it does not specifically limit as polyolefin, The polyolefin mentioned above can be selected suitably and can be used.
The base material layer may be added with the above-described other additives as necessary within a range not impeding the achievement of the object of the present invention.

Although it does not specifically limit as a material which comprises an adhesive layer, The adhesive composition which has a rubber-type resin component as a main component is used preferably.
As a rubber-type resin component, what is used as a base polymer of adhesives, such as a styrene-type elastomer, a urethane-type elastomer, an ester-type elastomer, an olefin-type elastomer, can be especially used without a restriction | limiting.
Of these, styrenic elastomers are preferred from the viewpoints of adhesive properties and moldability.

  Specifically, AB- such as styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS), etc. A type block polymer; A type B block polymer such as styrene-butadiene (SB), styrene-isoprene (SI), styrene-ethylene-butylene (SEB), styrene-ethylene-propylene (SEP); styrene-butadiene rubber ( SBR) and other styrene random copolymers; ABC polymer styrene-olefin crystal block polymers such as styrene-ethylene-butylene-olefin crystals (SEBC); olefin crystals-ethylene-butylene-olefin crystals (CEBC) ) Etc. The crystalline olefin based block polymers, ethylene -α- olefin, ethylene - propylene -α- olefin, olefin elastomers propylene -α- olefin such news, etc. These hydrogenated products thereof. These rubber-based resin components may be used alone or in combination of two or more.

In particular, styrene-ethylene-butylene-styrene (SEBS) is more preferable. When this styrene-based elastomer is used, a surface protective film can be easily formed by coextrusion, and a surface protective film having good temporary adhesion to an adherend can be provided.
When the styrenic elastomer has an unsaturated double bond derived from a conjugated diene, the unsaturated double bond is preferably less from the viewpoint of improving heat resistance and weather resistance, and hydrogenated as necessary. Preferably, at least 80% of the double bonds of the conjugated diene moiety are saturated by hydrogenation. A more preferable ratio of hydrogenation is 90% or more, and further preferably 95 to 100%.

  The weight average molecular weight in terms of polystyrene measured by GPC (gel permeation chromatography) of the styrene elastomer is preferably in the range of 30,000 to 400,000, more preferably in the range of 50,000 to 200,000. This is because the cohesive force of the pressure-sensitive adhesive layer is ensured and adhesive residue on the adherend when the surface protective film is peeled off is prevented. Moreover, it is for ensuring a suitable adhesive force and preventing the increase in a solution viscosity and a melt viscosity at the time of preparation of an adhesive composition or manufacture of a surface protection film.

  By using a tackifier as a material constituting the pressure-sensitive adhesive layer, the adhesive strength of the pressure-sensitive adhesive layer can be effectively increased. In this case, it is preferable to use the surface protective film in an amount that can prevent adhesive residue when the surface protective film is peeled off from the adherend. For example, the blending ratio of the tackifier is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, and still more preferably 10 parts by weight or less with respect to 100 parts by weight of the rubber-based resin component.

  Examples of the tackifier include petroleum-based resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymer systems and alicyclic copolymers, and coumarone-indene resins. , Terpene resin, terpene phenol resin, rosin resin such as polymerized rosin, (alkyl) phenol resin, xylene resin or hydrogenated products thereof are generally used for adhesives Things can be used without particular limitation. These tackifiers may be used alone or in combination of two or more.

It is more preferable to use a hydrogenated tackifier in order to improve the peelability and weather resistance. Moreover, you may use the tackifier marketed as a blend with an olefin resin.
When a softener is further used as the material constituting the pressure-sensitive adhesive layer, the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer can be effectively increased.
Examples of the softening agent include low molecular weight diene polymers, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene, and derivatives thereof. Examples of these derivatives include those having an OH group or a COOH group at one or both ends. Specific examples include hydrogenated polybutadiene diol, hydrogenated polybutadiene monool, hydrogenated polyisoprene diol, and hydrogenated polyisoprene monool.

Of these, hydrogenated products of diene polymers such as hydrogenated polybutadiene and hydrogenated polyisoprene, and olefinic softeners are preferred. This is because the adhesive strength of the pressure-sensitive adhesive layer can be appropriately increased. As such a softening agent, for example, “Kuraprene LIR-200” manufactured by Kuraray Co., Ltd. is used. These softeners may be used alone or in combination of two or more.
The number average molecular weight of the softening agent is not particularly limited, but is preferably in the range of 5000 to 100,000, and more preferably in the range of 10,000 to 50,000. This is because the material transfer from the pressure-sensitive adhesive layer to the adherend can be suppressed to prevent heavy peeling and the like, and the improvement of the adhesive strength can be ensured.

  When the pressure-sensitive adhesive composition is composed of a rubber-based resin component and a softening agent, the amount of the softening agent is not particularly limited, but the total amount of the rubber-based resin component and the softening agent is 100 parts by weight. On the other hand, the blending ratio of the softener is preferably 40 parts by weight or less, more preferably 20 parts by weight or less, and still more preferably 10 parts by weight or less. It is because the adhesive residue at the time of peeling from an adherend after high temperature or outdoor exposure can be reduced.

As the material constituting the pressure-sensitive adhesive layer, other additives may be used as necessary within a range not impeding the achievement of the object of the present invention. Examples of such additives include known ones such as ultraviolet absorbers, antioxidants, and adhesion progress inhibitors.
Examples of the adhesion progress preventing agent include fatty acid amides, polyethyleneimine long-chain alkyl grafts, soybean oil-modified alkyd resins (for example, Arakawa Chemical Co., Ltd., trade name “Arachid 251”), tall oil-modified alkyd resins (for example, Arakawa). Chemical name, “Arachid 6300”, etc.).
Although the thickness in particular of an adhesive layer is not restrict | limited, It is about 0.5-50 micrometers, Preferably it is 1-30 micrometers, More preferably, it is 2-30 micrometers.

The surface protective film of the present invention can be produced by lamination and integration by co-extrusion by a known method such as an inflation method or a T-die method.
Moreover, the surface protection film of this invention is manufactured industrially as a wound body which wound the elongate film in roll shape, for example. When the surface protective film is a wound body, the pressure-sensitive adhesive layer is in close contact with the side of the substrate opposite to the side where the pressure-sensitive adhesive layer is formed. In the present invention, even in such a case, and even when the surface protective film is a relatively wide wound body or the like, the pressure-sensitive adhesive layer can be easily peeled from the substrate. That is, the wound body can be easily rewound.
Furthermore, since it is not necessary to subject the surface opposite to the pressure-sensitive adhesive layer of the base material to a friction process or to form a release layer by coating, a surface protective film can be produced with high productivity and low cost. It becomes possible.

Hereinafter, examples of the resin composition and the surface protective film of the present invention will be described in detail. However, the present invention is not limited to the following examples.
Example 1
The surface protective film of this example is composed of a base material having a two-layer structure of a surface layer and an intermediate layer, and an adhesive layer adjacent to the intermediate layer.
As the material constituting the surface layer, 100 parts by weight of a thermoplastic silicone elastomer containing a urea bond (manufactured by Wacker Chemie, product number: GENIOMER80), 40 parts by weight of maleic anhydride-modified polypropylene (manufactured by Mitsubishi Chemical, Modic AP P604V) A raw material kneaded and pelletized in advance using a twin-screw extruder was prepared.

As the material constituting the intermediate layer, the same kind of polypropylene as the material constituting the surface layer was prepared.
As a material constituting the pressure-sensitive adhesive layer, 100 parts by weight of a styrene-based elastomer (SEBS, manufactured by Kraton Polymer Co., Ltd., product number: G1657, ethylene-butylene ratio = 2.6) composed of a hydrogenated product of a styrene-butadiene copolymer. A pressure-sensitive adhesive composition containing 5 parts by weight of Alcon P-125 (manufactured by Arakawa Chemical Co., Ltd.) as a tackifier was kneaded with a twin screw extruder and pelletized.

  A surface layer made of each of the above materials, an intermediate layer, and an adhesive layer were coextruded by a T-die method to form a film. The surface protection film thus formed is wound around a paper core having an outer diameter of 3 inches, thereby comprising a three-layer structure of surface layer (thickness 6 μm) / intermediate layer (thickness 30 μm) / adhesive layer (thickness 6 μm). A wound body of a surface protective film (width 1300 mm) was obtained.

(Example 2)
As a material constituting the surface layer, 100 parts by weight of a thermoplastic silicone elastomer containing a urea bond (manufactured by Wacker Chemie, product number: GENIOMER 80), 600 parts by weight of maleic anhydride-modified polypropylene (manufactured by Mitsubishi Chemical Corporation, Modic AP P604V), Except that, a wound body of a surface protective film having the same thickness and the same width was obtained in the same manner as in Example 1.

(Example 3)
As a material constituting the surface layer, except that 100 parts by weight of a thermoplastic silicone elastomer containing a urea bond (manufactured by Wacker Chemie, product number: GENIOMER80), 40 parts by weight of maleic anhydride-modified polypropylene and 3000 parts by weight of block polypropylene, In the same manner as in Example 1, a wound body of a surface protective film having the same thickness and the same width was obtained.

Example 4
As a material constituting the surface layer, except that it is 100 parts by weight of a thermoplastic silicone elastomer containing a urea bond (manufactured by Wacker Chemie, product number: GENIOMER 80), 600 parts by weight of maleic anhydride-modified polypropylene, and 3000 parts by weight of block polypropylene, In the same manner as in Example 1, a wound body of a surface protective film having the same thickness and the same width was obtained.

(Comparative Example 1)
Example 1 except that only a polypropylene graft copolymer having polyorganosiloxane as a graft chain (product number: BY27-201, manufactured by Toray Dow Corning Silicone Co., Ltd.) was used as a material constituting the surface layer. Similarly, the wound body of the surface protection film which has the same thickness and the same width | variety of each layer was obtained.

(Comparative Example 2)
As a material constituting the surface layer, a wound body of a surface protective film having the same thickness and the same width was obtained in the same manner as in Example 1 except that only block polypropylene was used.

(Comparative Example 3)
The thickness of each layer is the same as in Example 1 except that only a thermoplastic silicone elastomer containing a urea bond (manufactured by Wacker Chemie, product number: GENIOMER80) is used as the material constituting the surface layer. A wound body of a surface protective film having a width was obtained.

(Comparative Example 4)
Except that 100 parts by weight of a thermoplastic silicone elastomer containing urea bond (manufactured by Wacker Chemie, product number: GENIOMER 80) and 4000 parts by weight of block polypropylene were used as the material constituting the surface layer, in the same manner as in Example 1. And the thickness of each layer was the same, and the wound body of the surface protection film which has the same width | variety was obtained.

(Evaluation)
(1) Self-back surface peeling force Each surface protection film was affixed on the flat acrylic board from the adhesive layer side. Moreover, what cut out each surface protection film to the magnitude | size of width 25mm x length 150mm was prepared separately.
Using the 2 kg rubber roller from the pressure-sensitive adhesive layer side, cut each surface protective film of Example and Comparative Example to the back surface of the surface layer of each surface protective film of Examples and Comparative Examples affixed to an acrylic plate to 2 m. Affixed at a rate of / min. This was left in a room at 23 ± 2 ° C. for 30 minutes. Thereafter, in accordance with JIS Z 0237, peeling between the surface protective films was performed, and the 180 ° peel strength at a width of 25 mm was measured at a tensile speed of 30 m / min to obtain the self-back surface peel force.

(2) Rewindability of wide winding body The film end of each 1300 mm wide winding body was held and pulled by hand, and the winding body was rewound by about 1 m. When rewinding, it was visually observed whether or not the surface protective film had partial elongation or deformation. The case where there was no partial expansion or deformation was judged as “◯”, and the case where there was partial expansion or deformation was judged as “x”.

(3) Transferability Ratio of the adhesive strength B of the surface protective film sampled after winding as a wound body with respect to the adhesive strength A of the surface protective film sampled before winding as a wound body (B / A) Evaluated. Each surface protective film was attached to a flat acrylic plate at a speed of 2 m / min from the pressure-sensitive adhesive layer side using a 2 kg rubber roller. This was left in a room at 23 ± 2 ° C. for 30 minutes. Thereafter, in accordance with JIS Z 0237, the surface protective film was peeled off from the acrylic plate, and the 180 degree peel strength at 25 mm width was measured at a tensile speed of 30 m / min. The ratio of adhesive strength is expressed as a percentage (B / A × 100%). When it is 85% or more, “◯”, when it is 65% or more and less than 85%, “△”, when it is less than 65% Judged “x”.

(4) Cooling roll dirt The amount of extrusion of the release layer was 29 kg / h, and the dirt on the cooling roll surface after film formation for 2 hours was visually observed.
The results are shown in Tables 1 and 2 below.

  Not limited to various articles and members such as optical devices, metal plates, coated steel plates, resin plates, glass plates, etc. For all adherends that require prevention of dirt and scratches during transportation, processing or curing Can be used.

Claims (4)

  A resin composition comprising 100 parts by weight of a thermoplastic silicone elastomer having a polar bond and 10 to 700 parts by weight of an acid-modified polyolefin.   The resin composition formed by mix | blending 0.5-50 weight part of resin compositions of Claim 1 with respect to 100 weight part of polyolefin resin.   A surface protective film comprising a base material and an adhesive layer, wherein the base material has a release layer comprising the resin composition of claim 1 or 2 on the surface opposite to the adhesive layer of the base material. the film.   The surface protective film according to claim 3, wherein the pressure-sensitive adhesive layer contains a thermoplastic elastomer as a main component and is formed by coextrusion.