JP2008081589A - Surface-protecting film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface-protecting film capable of being obtained without impairing advantage of a coextrusion method enabling production in high productivity and at a low cost, e.g. formed in a wound body, etc., having a wide width, capable of readily releasing an adhesive layer from the rear of a substrate layer even when the substrate layer is bonded to the rear of the substrate layer and capable of readily rewinding the wound body. <P>SOLUTION: The surface-protecting film 1 obtained by coextrusion comprises a substrate layer 2 composed of a fluororesin or a silicone-based resin and a polyolefin, an intermediate layer 3 composed of a polyolefin laminated on one surface 2a of the substrate layer 2 and an adhesive layer 4 laminated to a surface 3b on the side opposite to the side to which the substrate layer 2 of the intermediate layer 3 is laminated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a surface protective film used to prevent adhesion of dust to the surface of the adherend and scratches on the surface of the adherend, and more specifically, a base material layer made of a material containing a polyolefin resin, The present invention relates to a surface protective film in which an intermediate layer and an adhesive layer are laminated.

  Conventionally, surface protective films have been used to protect articles and members. The surface protective film is, for example, adhered to the surface of various adherends such as an optical device, a metal plate, a coated steel plate, a resin plate, a glass plate, or the like when being transported, processed, or cured. It is used to prevent scratches.

  This type of surface protective film has a structure in which an adhesive layer is laminated on a base material layer. The surface protective film is manufactured by, for example, applying a pressure-sensitive adhesive solution containing an elastomer or the like to a base material layer made of a synthetic resin or the like, or coextruding the base material layer and the pressure-sensitive adhesive layer. The method of co-extrusion of the base material layer and the adhesive layer is advantageous because the productivity is high and the manufacturing cost can be reduced.

  The said surface protection film is manufactured industrially as a wound body which wound the elongate film in roll shape, for example. In the surface protective film having 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 was a strong demand for it to be easily performed.

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

  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, many mold release treatments have been performed on the back surface of the base material layer in order to improve the rewinding property of the wound body.

  As an example of the surface protection film subjected to the mold release treatment, in Patent Document 2 below, a base material layer made of a polyolefin resin and an adhesive layer are laminated, and the back surface of the base material layer is friction-treated with a solid. An adhesive tape is disclosed. Patent Document 2 also shows a configuration in which an intermediate layer made of craft paper, cloth, synthetic resin, or the like is provided between a base material layer and an adhesive layer.

On the other hand, in Patent Document 3 below, after a base material layer containing a polyolefin-based resin and a pressure-sensitive adhesive layer containing a thermoplastic elastomer are laminated and formed by a co-extrusion method, the pressure-sensitive adhesive of the base material layer A surface protective sheet is disclosed in which a release layer made of a release agent is formed on the back surface opposite to the side where the layers are laminated by a coating method.
Japanese Patent Laid-Open No. 2-252782 JP-A-2-252777 JP 2003-41216 A

  In Patent Document 1, as described in Patent Documents 2 and 3, it is not necessary to frictionally treat the back surface of the base material layer with a solid or to form a release layer by coating on the back surface of the base material layer. A surface protective film can be produced with low productivity and low cost. However, in patent document 1, although the rewinding property of a wound body is improved by comprising a base material layer using the polyethylene which has polyorganosiloxane as a graft chain, the effect was not enough.

  Furthermore, when the surface protection film of Patent Document 1 is a relatively wide wound body, when the wide wound body is rewound, the stress required for unwinding the entire width is locally applied to the grip portion by hand. In some cases, the surface protective film partially expands or deforms due to concentration of the target. When a partially extended or deformed surface protective film is used for a resin sheet having a relatively small thickness such as a prism sheet used in a liquid crystal display (LCD), for example, there is a problem that the resin sheet is warped.

  On the other hand, in Patent Document 2, the back surface of the base material layer is subjected to friction treatment with a solid, and this friction treatment can be performed relatively easily 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 base material layer.

  On the other hand, in Patent Document 3, a release layer is formed on the back surface of the base material layer. However, in order to form the release layer, it is necessary to perform steps such as application of a release agent, drying, and curing. there were. 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.

  The object of the present invention can be obtained without impairing the advantages of the co-extrusion method that can be produced with high productivity and low cost in view of the current state of the prior art described above. An object of the present invention is to provide a surface protective film that can easily peel the adhesive layer from the back surface of the base material layer and can easily rewind the wound body even if the adhesive layer is adhered to the back surface of the material layer. .

  The present invention relates to a surface protective film obtained by coextrusion, comprising a base layer composed of a fluororesin or silicone resin and a polyolefin, and an intermediate layer composed of a polyolefin laminated on one surface of the base layer And an adhesive layer laminated on a surface opposite to the side on which the base material layer of the intermediate layer is laminated.

  In a specific aspect of the surface protective film according to the present invention, the fluorine resin or the silicone resin has a contact angle of 15 ° or more measured with n-hexadecane.

  In another specific aspect of the surface protective film according to the present invention, the base material layer is composed of a fluororesin and a polyolefin, and the fluororesin is a ternary copolymer composed of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. It is a coalescence.

  In still another specific aspect of the surface protective film according to the present invention, the base material layer is composed of a silicone resin and a polyolefin, and the silicone resin is a thermoplastic elastomer.

  In still another specific aspect of the surface protective film according to the present invention, the pressure-sensitive adhesive layer is composed of a pressure-sensitive adhesive composition containing a rubber-based resin component as a main component, and the rubber-based resin component includes a styrene-based polymer block (A) and an olefin. Block copolymer with a polymer block (B), block copolymer of a styrene polymer block (A) with a random copolymer block (B ′) of styrene and olefin, and / or hydrogenation thereof It is a styrenic elastomer with a main skeleton.

  In the surface protective film according to the present invention, a base material layer composed of a fluororesin or silicone resin and a polyolefin, an intermediate layer composed of a polyolefin, and an adhesive layer are laminated in this order. Even if the surface protective film is a wound body and the adhesive layer is adhered to the back surface of the base material layer, the surface protective film adhered from the back surface of the base material layer can be easily peeled off, making the wound body impossible. Can be rewound without Furthermore, when the surface protective film is a relatively wide wound body, the wound body can be easily rewound without the surface protective film partially extending or deforming.

  Furthermore, in this invention, since it is not necessary to perform a mold release treatment on the back surface of the base material layer, a surface protective film can be obtained without impairing the advantages of the coextrusion method that can be produced with high productivity and low cost. .

  The pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive composition containing a rubber-based resin component as a main component, and the rubber-based resin component is a block copolymer of a styrene-based polymer block (A) and an olefin-based polymer block (B). A block copolymer of a polymer block (A) and a random copolymer block (B ′) of styrene and olefin, and / or a styrene elastomer having a hydrogenated product thereof as a main skeleton, the surface A protective film can be easily obtained by coextrusion, and a surface protective film having good temporary adhesion to an adherend can be provided.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  In FIG. 1, the surface protection film which concerns on one Embodiment of this invention is shown with a partial notch front sectional drawing.

  As shown in FIG. 1, the surface protection film 1 is configured by laminating a base material layer 2, an intermediate layer 3, and an adhesive layer 4 in this order. That is, one surface 3a of the intermediate layer 3 is bonded to one surface 2a of the base material layer 2, and the other surface 3b opposite to the one surface 3a to which the base material layer 2 of the intermediate layer 3 is bonded is adhered. One side 4a of the layer 4 is joined. In the present invention, the surface protective film 1 is formed by coextrusion.

  The base material layer 2 is made of a fluororesin or silicone resin and polyolefin.

  It does not specifically limit as a fluorine resin or silicone resin which comprises the said base material layer 2, The thermoplastic resin in which melt extrusion molding is possible can be used.

  The fluorine-based resin or silicone-based resin preferably has a contact angle measured with n-hexadecane of 15 ° or more. The contact angle can be measured, for example, by molding a fluorine-based resin or a silicone-based resin into a plate having a smooth surface, and dropping n-hexadecane on the plate.

  Although it does not specifically limit as fluorine-type resin which comprises the said base material layer 2, The copolymer of the homopolymer of a fluorine-containing monomer, the olefin etc. which do not contain fluorine, such as a fluorine-containing monomer and ethylene, or propylene, and these Examples thereof include blends of polymers and blends of these polymers with non-fluorine (co) polymers.

  Specific examples of the fluororesin include, for example, terpolymers composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, polyvinylidene fluoride, chlorotrifluoroethylene / ethylene copolymer, tetrafluoroethylene / hexafluoro. Examples thereof include a propylene copolymer, a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, an ethylene-tetrafluoroethylene copolymer, and a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene. Among these, since the resin hardly deteriorates during molding, a fluorine-based resin having a melting point of 300 ° C. or lower is preferably used, and a terpolymer composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride is more preferably used. In addition, these fluororesins may be used independently and may be used together 2 or more types.

  The silicone resin constituting the base material layer 2 is not particularly limited as long as it can be melt-molded. However, a thermoplastic polyorganosiloxane skeleton (polyorganosiloxane includes polydimethylsiloxane, polymethylpropylsiloxane, polydipropyl). Siloxane, polymethyloctylsiloxane, polydioctylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, etc.) in the molecular chain.

  As the silicone resin, a thermoplastic elastomer is preferable. Examples of such a silicone-based resin include polymers such as polyethylene and polypropylene having a polyorganosiloxane as a graft chain, and a block copolymer composed of a polyorganosiloxane soft segment and an organic hard segment. In particular, the releasability of the back surface of the base material layer is enhanced, the compatibility with polyolefin is high, and the silicone resin does not easily migrate to the adhesive layer. Coalescence is preferably used. In addition, these silicone type resins may be used independently and may be used together 2 or more types.

  The polyolefin constituting the substrate layer 2 is not particularly limited. For example, polypropylene or a propylene polymer such as a block system or a random system composed of a propylene component and an ethylene component; ethylene such as a low density, high density, linear low density polyethylene, etc. Olefin polymers such as ethylene-α-olefin copolymers, olefin polymers of ethylene components and other monomers such as ethylene-vinyl acetate copolymers, ethylene-methyl methacrylate copolymers, and the like. These polyolefins may be used independently and may be used together 2 or more types.

  The material which comprises the base material layer 2 can be obtained by blending fluororesin or silicone resin, and polyolefin. The base material layer 2 can be formed using a blend of a fluororesin or silicone resin and a polyolefin.

  In the said base material layer 2, 5-95 weight part is preferable, as for the mixture ratio of the fluororesin with respect to 100 weight part of polyolefin, 10-90 weight part is more preferable, and 20-80 weight part is further more preferable. Moreover, 0.1-50 weight part is preferable, as for the mixture ratio of silicone resin with respect to 100 weight part of polyolefin, 0.5-30 weight part is more preferable, and 1-20 weight part is further more preferable. If the blending ratio of the fluorine-based resin or silicone-based resin is too small, the releasability may be inferior, and if it is too large, the interlayer adhesion may be inferior.

  As the material constituting the base material layer 2, 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 UV stabilizers, antioxidants, light stabilizers such as hindered amine light stabilizers, and antistatic agents. Furthermore, for example, fillers such as calcium oxide, magnesium oxide, silica, zinc oxide, and titanium oxide, pigments, anti-fogging agents, lubricants, antiblocking agents, and the like can be appropriately added as additives.

  The thickness of the base material layer 2 is not particularly limited, but is about 0.1 to 50 μm, preferably 0.5 to 30 μm, and more preferably 1 to 20 μm.

  The intermediate layer 3 is made of polyolefin. Although it does not specifically limit as polyolefin which comprises the intermediate | middle layer 3, The polyolefin mentioned above used for comprising the base material layer 2 can be used. The intermediate layer 3 is for achieving an anchoring action between the base material layer 2 and the adhesive layer 4 described later, and when the base material layer 2 and the adhesive layer 4 are directly coextruded without providing the intermediate layer 3. The sufficient interlayer strength cannot be secured.

  As the material constituting the intermediate layer 3, other additives described above may be used as necessary as long as the object of the present invention is not impaired.

  The thickness of the intermediate layer 3 is not particularly limited, but is usually about 1 to 100 μm, preferably 5 to 50 μm, and more preferably 10 to 30 μm.

  The combined thickness of the base material layer 2 and the intermediate layer 3 is about 10 to 200 μm, preferably 20 to 150 μm, and more preferably 30 to 100 μm.

  Although it does not specifically limit as a material which comprises the said adhesion layer 4, The adhesive composition which has a rubber-type resin component as a main component is used preferably.

  As said rubber-type resin component, what is used as a base polymer of adhesives, such as a styrene-type elastomer, a urethane-type elastomer, ester-type elastomer, an olefin-type elastomer, can be especially used without a restriction | limiting.

  Specific examples of the rubber resin component include styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butylene copolymer-styrene (SEBS), and styrene-ethylene-propylene. ABA type block polymer such as copolymer-styrene (SEPS); styrene-butadiene (SB), styrene-isoprene (SI), styrene-ethylene-butylene copolymer (SEB), styrene-ethylene-propylene AB block polymer such as copolymer (SEP); Styrene random copolymer such as styrene-butadiene rubber (SBR); AB such as styrene-ethylene-butylene copolymer-olefin crystal (SEBC) -C type styrene-olefin crystal block polymer; C-B-C type olefin crystal block polymer such as crystal-ethylene-butylene copolymer-olefin crystal (CEBC); ethylene-α-olefin, ethylene-propylene-α-olefin, propylene-α-olefin, etc. Examples thereof include olefin-based elastomers and hydrogenated products thereof. These rubber-based resin components may be used alone or in combination of two or more.

  As the rubber resin component, a block copolymer of a styrene polymer block (A) and an olefin polymer block (B), a styrene polymer block (A) and a random copolymer block of styrene and olefin ( A block copolymer with B ′) and / or a styrene elastomer having a hydrogenated product thereof as a main skeleton is preferably used, and a styrene / ethylene-butylene copolymer / styrene (SEBS) is more preferably used. When this styrene-based elastomer is used, a surface protective film can be easily obtained by coextrusion, and a surface protective film having good temporary adhesion to an adherend can be provided.

  When the rubber-based resin component has an unsaturated double bond derived from an olefin, the unsaturated double bond is preferably as small as possible from the viewpoint of improving heat resistance and weather resistance, and hydrogenated as necessary. Is preferred.

  In the styrene-based elastomer, the conjugated diene block in the conjugated diene polymer block that is the olefin polymer block (B) or the conjugated diene portion in the random copolymer block (B ′) of styrene and the conjugated diene that is the olefin. It is preferred that at least 80% of the heavy bonds are saturated by hydrogenation. A more preferable ratio of hydrogenation is 90% or more, and further preferably 95 to 100%. When the proportion of hydrogenation is less than 80%, heat resistance and weather resistance may be inferior.

  The polystyrene-equivalent weight average molecular weight 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. If the weight average molecular weight is too small, the cohesive force of the pressure-sensitive adhesive layer is lowered, and therefore, an adhesive residue may be generated on the adherend when the surface protective film is peeled off. If the weight average molecular weight is too large, the adhesive strength is insufficient, and troubles such as an increase in solution viscosity and melt viscosity may occur during the preparation of the pressure-sensitive adhesive composition and the production of the surface protective film.

  When a tackifier is used as the material constituting the adhesive layer 4, the adhesive force of the adhesive layer can be effectively increased. But when there is too much usage-amount of a tackifier, when a surface protection film is peeled from a to-be-adhered body, there exists a possibility that adhesive residue may arise.

  When the adhesive layer 4 is constituted using the adhesive composition containing the rubber-based resin component and the tackifier, the blending ratio of the tackifier is 40 parts by weight or less with respect to 100 parts by weight of the rubber-based resin component. The amount is preferably 30 parts by weight or less, more preferably 10 parts by weight or less.

  Examples of the tackifier include petroleum-based resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymer systems and alicyclic copolymers, and coumarone-indene systems. Resin, 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. Can be used without particular limitation. These tackifiers may be used alone or in combination of two or more.

  A hydrogenated tackifier is more preferably used to improve peelability and weather resistance. In addition, you may use the tackifier marketed as a blend with an olefin resin.

  When a softening agent is used as the material constituting the adhesive layer 4, the adhesive force of the 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 the derivative include those having an OH group or a COOH group at one end or both ends. Specific examples of the derivatives include hydrogenated polybutadiene diol, hydrogenated polybutadiene monool, hydrogenated polyisoprene diol, and hydrogenated polyisoprene monool. Since the adhesive strength of the adhesive layer can be increased moderately, hydrogenated products of diene polymers such as hydrogenated polybutadiene and hydrogenated polyisoprene, olefinic softeners, and the like are preferably used. As the softener, 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 if the number average molecular weight is too small, substance transfer from the adhesive layer to the adherend may occur, which may cause heavy peeling. On the other hand, if the number average molecular weight is too large, the effect of improving the adhesive strength tends to be poor. Therefore, the number average molecular weight of the softening agent is preferably in the range of 5000 to 100,000, and more preferably in the range of 10,000 to 50,000.

  When the adhesive layer 4 is constituted using the adhesive composition containing the rubber-based resin component and the softener, the blending amount of the softener is not particularly limited. Adhesive residue tends to occur when peeling. Therefore, the blending ratio of the softening agent is preferably 40 parts by weight or less, more preferably 20 parts by weight or less, and further preferably 10 parts by weight or less with respect to 100 parts by weight of the total of the rubber-based resin component and the softening agent.

  As the material constituting the pressure-sensitive adhesive layer 4, other additives may be used as necessary within a range that does not hinder achievement of the object of the present invention. Examples of such additives include 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 the said adhesion layer 4 is not restrict | limited, It is about 0.5-50 micrometers, Preferably it is 1-30 micrometers, More preferably, it is 2-30 micrometers.

  As the method for producing the surface protective film 1, a method of laminating and integrating by co-extrusion by a known method such as an inflation method or a T-die method is used.

  The said surface protection film 1 is manufactured industrially as a wound body which wound the elongate film in roll shape, for example. When the surface protection film 1 is a wound body, the back surface 2b opposite to the side on which the intermediate layer 3 of the base material layer 2 is bonded and the intermediate layer 3 of the adhesive layer 4 are bonded. One surface 4a is in close contact with the other surface 4b on the opposite side.

  In the present invention, since the above-described configuration is provided, for example, the long surface protective film 1 is wound into a roll shape to form a wound body, and the back surface 2b of the base material layer 2 and the other surface of the adhesive layer 4 Even if 4b adheres closely, the adhesion layer 4 can be easily peeled from the back surface 2b of the base material layer 2. That is, the outer surface protective film 1 can be easily peeled from the inner surface protective film 1, and the wound body can be rewound without difficulty. Furthermore, even when the surface protective film is a relatively wide wound body or the like, the wound body can be easily rewound.

  Furthermore, the surface protective film 1 can be obtained with high productivity and low cost, without subjecting the back surface 2b of the base material layer 2 to a friction treatment or forming a release layer by coating.

  Hereinafter, the effects of the present invention will be clarified by giving examples and comparative examples of the present invention. In addition, this invention is not limited to a following example.

(Example 1)
As a material constituting the base material layer, 100 parts by weight of polypropylene and a terpolymer composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (manufactured by Sumitomo 3M, product number: Dinion THV500G, melting point 165 ° C., MFR10 ( 265 ° C./49 N)) 50 parts by weight of dry blended pellets were prepared.

  As a material constituting the intermediate layer, 100 parts by weight of the same kind of polypropylene as the material constituting the base material layer was prepared.

  As a material constituting the adhesive layer, 100 parts by weight of a styrene-based elastomer (SEBS, manufactured by Kraton Polymer, product number: G1657, ethylene-butylene ratio = 2.6) made 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 Industries) as a tackifier was kneaded with a twin screw extruder and pelletized.

  A base material 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 on a paper core having an outer diameter of 3 inches, thereby comprising a three-layer structure of a base material (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 base material layer, 100 parts by weight of polypropylene and 7.5 parts by weight of polyorganosiloxane copolymer containing urea group (manufactured by Wacker Chemie, product number: GENIOMER80) are dry blended in pellets. In the same manner as in Example 1 except that was used, a wound body of a surface protective film having the same thickness and the same width was obtained.

(Example 3)
As a material constituting the base material layer, 100 parts by weight of polypropylene and 10 parts by weight of a polypropylene graft copolymer having polyorganosiloxane as a graft chain (product number: BY27-201, manufactured by Toray Dow Corning Silicone Co., Ltd.) In the same manner as in Example 1 except that a material obtained by dry blending with a pellet was used, 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 base material layer, 100 parts by weight of polypropylene, 5 parts by weight of a polyorganosiloxane copolymer containing urea group (manufactured by Wacker Chemie, product number: GENIOMER 80), and polyorganosiloxane as a graft chain are included. In the same manner as in Example 1 except that 5 parts by weight of a polypropylene graft copolymer (product number: BY27-201, manufactured by Toray Dow Corning Silicone Co., Ltd.) and dry blended with pellets were used. A wound body of a surface protective film having the same thickness and the same width was obtained.

(Comparative Example 1)
As a material constituting the base material 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 100 parts by weight of polypropylene was used. .

(Comparative Example 2)
Except for using only 100 parts by weight of a polypropylene graft copolymer having polyorganosiloxane as a graft chain (product number: BY27-201, manufactured by Dow Corning Silicone Co., Ltd.) as a material constituting the base layer. 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 3)
As a material constituting the base material layer, a terpolymer composed of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (manufactured by Sumitomo 3M, product number: DIONION THV500G, melting point 165 ° C., MFR 10 (265 ° C./49 N)) Except having used only 100 weight part, it carried out similarly to Example 1, and obtained the wound body of the surface protection film which the thickness of each layer is the same and has the same width | variety.

(Comparative Example 4)
Each layer was the same as in Example 1 except that only 100 parts by weight of a polyorganosiloxane copolymer containing a urea group (manufactured by Wacker Chemie, product number: GENIOMER80) was used as the material constituting the base material layer. The wound body of the surface protection film which has the same thickness and the same width was obtained.

(Comparative Example 5)
A polyolefin resin composition obtained by extruding a mixture of 100 parts by weight of polypropylene and 5 parts by weight of polydimethylsiloxane having an average molecular weight of 100,000 with a twin screw extruder at 220 ° C. and the same pressure-sensitive adhesive composition as in Example 1. Were coextruded so that the thickness of each layer was 36 μm and 6 μm, respectively, to obtain a wound body of a surface protective film having the same width as in Example 1.

(Evaluation)
(1) Self back peeling force Each surface protection film was affixed on the flat acrylic board from the adhesion layer side. Moreover, what cut out each surface protection film to the magnitude | size of width 25mm x length 150mm was prepared separately.

  On the back surface of the base material layer of each surface protective film of Examples and Comparative Examples pasted on an acrylic plate, each surface protective film of Examples and Comparative Examples cut out from the adhesive layer side using a 2 kg rubber roller, Affixed at a speed of 2 m / min. This was left in a room at 23 ° C. ± 2 ° C. for 30 minutes. Thereafter, in accordance with JIS Z0237, peeling between the surface protective films was performed, and the 180-degree peeling strength at 25 mm width and 100 mm was measured at a speed of 30 m / min.

(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) Base material layer adhesion test Each surface protection film was affixed on the flat acrylic board from the adhesion layer side. Using a 2 kg rubber roller, a 25 mm-wide silicone adhesive tape (manufactured by Sliontec Co., Ltd.) was attached to the back surface of the base material layer of each surface protective film attached to the acrylic plate at a speed of 2 m / min. This was left in a room at 23 ° C. ± 2 ° C. for 24 hours. Thereafter, the silicone pressure-sensitive adhesive tape was peeled off from the back surface of the base material layer, and the base material layer was peeled off on the peeled surface, and the presence or absence of roughening of the base material layer was observed visually and with a microscope. The case where there was no peeling of the base material layer or the roughness of the base material layer was judged as “◯”, and the case where the base material layer was peeled off or the base material layer was rough was judged as “x”.

(4) Contact angle of n-hexadecane Each pellet of fluorine-based resin or silicone-based resin used as a material constituting the base layer is preheated at 200 ° C. for 2 minutes, pressed at 10 MPa for 2 minutes, and then cooled and solidified by a water-cooled press. Thus, a plate having a smooth surface was produced. As a release sheet at the time of pressing, a polytetrafluoroethylene sheet (manufactured by Nitto Denko Corporation, Nitoflon) was used in the case of a silicone resin, and a PET film subjected to silicone release processing was used in the case of a fluorine resin.

  In accordance with JIS R 3257, n-hexadecane was dropped on the obtained plate, and the contact angle was measured using a contact angle measuring device. In addition, since the polydimethylsiloxane used in Comparative Example 5 was oily, the contact angle could not be measured.

(5) Transferability Ratio of the adhesive strength B of the surface protective film sampled after winding as a wound body 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 adhesive layer side using a 2 kg rubber roller. This was left in a room at 23 ° C. ± 2 ° C. for 30 minutes. Thereafter, in accordance with JIS Z0237, the surface protective film was peeled from the acrylic plate, and the 180 degree peel strength at 25 mm width and 100 mm was measured at a speed of 30 m / min. The ratio (B / A) of the 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%, “Δ”, 65% A case of less than “x” was judged.

  The results are shown in Tables 1 and 2 below.

The partial notch front sectional drawing of the surface protection film which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Surface protective film 2 ... Base material layer 2a ... One side 2b ... Back side 3 ... Intermediate | middle layer 3a ... One side 3b ... Other side 4 ... Adhesive layer 4a ... One side 4b ... Other side

Claims (5)

A surface protective film obtained by coextrusion,
A base material layer made of fluororesin or silicone resin and polyolefin, an intermediate layer made of polyolefin laminated on one surface of the base material layer, and a side of the intermediate layer on which the base material layer is laminated A surface protective film comprising an adhesive layer laminated on the opposite surface.   The surface protective film according to claim 1, wherein the fluorine-based resin or the silicone-based resin has a contact angle measured by n-hexadecane of 15 ° or more. The base material layer comprises a fluororesin and a polyolefin,
The surface protective film according to claim 1 or 2, wherein the fluororesin is a terpolymer comprising tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. The base layer is composed of a silicone resin and a polyolefin,
The surface protection film according to claim 1, wherein the silicone resin is a thermoplastic elastomer. The pressure-sensitive adhesive layer is made of a pressure-sensitive adhesive composition containing a rubber-based resin component as a main component,
The rubber resin component is a block copolymer of a styrene polymer block (A) and an olefin polymer block (B), a styrene polymer block (A) and a random copolymer block of styrene and olefin (B The surface protective film according to any one of claims 1 to 4, which is a styrene-based elastomer having a block copolymer with ') and / or a hydrogenated product thereof as a main skeleton.

Images