JP2008080626A - Surface protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface protective film which has high adhesion, excellent sliding and rewinding properties of the back surface and excellent unwinding characteristics, including reduced unwinding tension, producing no wrinkles or cracks on lamination on a substrate and allowing easy and high-speed lamination. <P>SOLUTION: The surface protective film has an adhesive layer laminated on one side and a release layer laminated on the other side. The release layer contains a polyolefinic resin and a silicone compound, and its surface roughness Ra is 250-5,000 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention does not provide a surface protective film that is optimal for surface protection of resin plates, metal plates, etc., particularly for resin plates whose surfaces have been subjected to uneven processing such as prism processing by molding. It is what.

  The surface protective film is used for surface protection for preventing scratches during processing of an adherend such as a resin plate or a metal plate, during transportation, and during storage. The surface protective film is temporarily attached to the surface of a resin plate or the like with an appropriate adhesive force, and usually remains attached to an adherend such as a resin plate during processing such as heating, molding, or cutting. Used and peeled off at the stage of final use of the resin plate or the like.

  The surface protective film has an appropriate adhesive strength that does not peel off during processing, and does not change with time even if it is applied for a long time. It is desirable that there is no adhesive residue of the adhesive and the base material does not break.

  In particular, when used on a resin plate having irregularities formed by prism processing, embossing, mat processing, etc. on the surface, the contact area between the adhesive layer and the resin plate is small, so the adhesion is higher than the smooth surface. It needs to be designed with power.

  In order to solve this problem, a general formula A-B-A (where A represents a styrene polymer block and B represents a butadiene polymer block, an isoprene polymer block, or ethylene) is provided on one side of a base film such as polyolefin. A surface protective film having a pressure-sensitive adhesive layer formed by mixing a block copolymer (which represents a butylene copolymer block) and a tackifying resin is known (see Patent Document 1).

  The pressure-sensitive adhesive layer composed of a block copolymer and a tackifying resin has a very high adhesive strength, and therefore can achieve high adhesive strength and excellent adhesion to a resin plate having irregularities. it can. However, on the other hand, the film as the base material is also closely adhered, and when the surface protection film wound in a roll shape is unwound and used, the adhesive layer and the film are blocked so that they are difficult to peel off. There was a problem with poor takeout. In addition, there is a problem that the adhesive force is increased during sticking to a resin plate or the like, during processing, during transportation, and during storage, and is difficult to peel off.

  In order to improve this problem, an adhesive layer is formed on one side of a base film made of a polyolefin resin, and the main components of the adhesive layer are a hydrogenated resin of a styrene random copolymer and an ethylene-α-olefin copolymer elastomer. Such a surface protective film is known (see Patent Document 2).

  The pressure-sensitive adhesive layer composed of a hydrogenated resin of a styrene random copolymer and an ethylene-α-olefin copolymer elastomer has a lower adhesive force than a pressure-sensitive adhesive composed of a block copolymer and a tackifying resin, so that the above winding Although it is preferable from the standpoint of take-out property, it is difficult to obtain sufficient adhesive strength when the center line average roughness of the unevenness is 3 μm or more with respect to the resin plate having unevenness, and the adherend is limited. was there.

  As a method for improving these, a rough surface with a matte embossing and a first surface having a smooth surface containing a styrenic thermoplastic elastomer and an adhesive resin having an intermediate block of saturated rubber and no adhesive coating. A surface protective film is known which includes a second surface having a surface and is coextruded (see Patent Document 3).

  However, since this surface protective film cannot be wound up from the point of blocking unless embossed, it is necessary to emboss it in the same process as coextrusion, but in order to obtain a stable rewinding property Processing speed and productivity have to be reduced, and there are problems such as appearance defects such as scratches and sagging.

  There has also been proposed a method in which a resin layer (release layer) in which silicone fine particles are added to and blended with an olefin resin and an adhesive layer are directly or indirectly laminated and integrated (see Patent Document 4).

However, in such a method, due to the adhesive properties of the adhesive layer, a phenomenon in which the silicone fine particles are partly taken into the adhesive layer occurs, roll contamination by the dropped fine particles, and when temporarily attaching the surface protection film to the adherend, There has been a problem that appearance defects such as imprints and scratches occur on the adherend surface due to the dropped fine particles.
Japanese Patent No. 58-30911 Japanese Patent No. 3560006 JP 2005-48161 A JP 2000-345125 A

  The present invention solves the above problems and has a high adhesive force even when used on a resin plate or the like whose surface has been subjected to uneven processing such as prism processing, embossing, and mat processing by molding processing or the like. Excellent sliding and unwinding properties on the back, unwinding characteristics (reducing unwinding tension, and easy and high-speed bonding without wrinkles or scratches when bonding to the adherend. It is intended to provide an excellent surface protection film.

  The present invention employs the following means in order to solve such problems.

  That is, the surface protective film of the present invention is formed by laminating an adhesive layer on one side and a release layer on the other side, and the release layer contains at least a polyolefin resin and a silicone compound, and has a surface roughness Ra of 250. It is characterized by being in the range of ˜5,000 nm.

  According to the present invention, the above-mentioned problems are solved, and the surface has a high adhesive force even when used on a resin plate or the like whose surface is subjected to uneven processing such as prism processing, embossing, and mat processing by molding processing. Excellent slipperiness and unwinding at the back, workability at the time of bonding (reducing unwinding tension, and without wrinkles or scratches when bonding to the adherend easily and at high speed It is possible to provide a surface protective film excellent in bonding process).

  The surface protective film of the present invention is formed by laminating an adhesive layer on one side and a release layer on the other side. The release layer contains at least a polyolefin-based resin and a silicone compound, and has a surface roughness Ra of 250 to 5. , A surface protective film in the range of 1,000 nm.

  First, the surface protection film of this invention is demonstrated using drawing.

  FIG. 1 is a schematic cross-sectional view showing an example of a surface protective film. An adhesive layer 1 and a release layer 2 are sequentially laminated.

  FIG. 2 is a schematic cross-sectional view showing a more preferred example of the surface protective film. The pressure-sensitive adhesive layer 1, the base material layer 3, and the release layer 2 are sequentially laminated.

  In the present invention, the release factor R of the surface protective film is defined by the following formula.

  For resin plates with irregularities such as prism processing, embossing, and mat processing on the surface by molding, etc., high adhesive strength is required, but mold release from the point of unwinding It is preferable that the adhesive strength to the layer surface is low. When the surface protective film is used by being attached to a resin plate having irregularities, the release coefficient is preferably 0.25 or less, more preferably 0.10 or less.

  In the surface protective film of the present invention, the release layer contains at least a polyolefin resin and a silicone compound.

  The release layer polyolefin resin is preferably at least one polyolefin resin selected from polyethylene resin, polypropylene resin, ethylene-propylene copolymer, and propylene-α-olefin copolymer. Examples of the polyethylene resin include low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene. Examples of the ethylene-propylene copolymer include a random copolymer and / or a block copolymer. As appropriate for the release layer, ethylene-α-olefin copolymer, ethylene-ethyl (meth) acrylate copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-n-butyl (meth) acrylate copolymer A resin such as an ethylene-vinyl acetate copolymer may be used.

  The silicone compound in the release layer preferably contains at least one compound having a silicone structure given by the following formula 2.

(In the formula, R ₁ represents the same or different hydrocarbon group having 1 to 12 carbon atoms. R ₂ represents the same or different hydrocarbon group having 1 to 12 carbon atoms, a hydrogen atom, or a hydroxyl group, n is a positive integer.)
The silicone compound preferably has an MFR (melt mass flow rate) defined by JIS K7210 (1999) as close as possible to the polyolefin resin. MFR is a numerical value indicating the fluidity at the time of melting of the resin. When the difference between the two MFRs is 50 g / 10 min or more, the dispersibility of the silicone compound is deteriorated and the silicone compound is likely to be aggregated. There is a tendency to increase the occurrence of fish eyes.

  In the surface protective film of the present invention, as a preferable form of the silicone compound, the silicone compound is composed of a silicone mixture in which a resin and a silicone resin are uniformly dispersed. More preferably, at least one selected from a polyethylene-silicone mixture in which polyethylene and silicone resin are uniformly dispersed, a polypropylene-silicone mixture in which polypropylene and silicone resin are uniformly dispersed, and / or a mixture thereof. Consists of. More preferably, it consists of a polypropylene-silicone mixture from the viewpoint of dispersibility with resin, processability, mechanical strength, and surface roughness.

  In the surface protective film of the present invention, as the polypropylene-silicone mixture, one or more types can be appropriately selected from an oil type, a graft type, and / or a mixture thereof.

  The oil type indicates a polypropylene-silicone mixture formed by kneading an ultra-high molecular weight silicone compound with a high concentration in a polypropylene resin, but has a small friction coefficient when used in the release layer of the present invention. However, there is a problem that the unwinding tension is lowered, but the silicone compound bleeds out over time or moves to the adhesive layer during long-term storage.

  The graft type refers to a polypropylene-silicone mixture formed by graft polymerization of a reactive polyorganosiloxane to a polypropylene resin, and even when used as a release layer as in the surface protective film of the present invention, the silicone compound bleeds. Since problems such as out and migration do not occur, a release layer having excellent contamination resistance can be formed. In the surface protective film of the present invention, the polypropylene-silicone mixture is preferably formed by graft polymerization of a reactive polyorganosiloxane to a polypropylene resin.

  In the surface protective film of the present invention, as the molecular weight of the silicone resin component of the polypropylene-silicone mixture, the weight average molecular weight (Mw) is preferably 100,000 or more, more preferably 300,000 or more. When Mw is lower than 100,000, the silicone resin component tends to bleed out and may cause contamination of the adhesive layer.

  In the surface protective film of the present invention, the release layer has a surface roughness Ra in the range of 250 to 5,000 nm. Particularly when a graft type polypropylene-silicone mixture is used as the silicone compound of the release layer, the surface roughness Ra of the release layer can be easily adjusted to 250 to 5,000 nm, and the release factor is small. The unwinding tension becomes smaller.

The content of the silicone resin in the release layer is preferably from 0.1 to 30%, more preferably from 1.0 to 20%. When the content of the silicone resin is less than 0.1%, there is a problem that sufficient surface roughness cannot be obtained and the unwinding tension of the surface protection film is increased. There is a problem in that the appearance becomes worse and appearance defects such as fish eyes increase.
The surface protective film of the present invention is formed by laminating at least an adhesive layer and a release layer. Although it may be a two-layer laminated film of an adhesive layer and a release layer, more preferably, it has a base material layer made of a resin mainly composed of a polyolefin resin between the adhesive layer and the release layer. It is preferable to form a three-layer laminated film.

  As a preferable form of the surface protective film of the present invention, there is a configuration in which a release layer is formed on one side of a base material layer made of polyolefin resin by a co-extrusion method, and an adhesive layer is formed on the opposite side. It is done.

  Examples of the polyolefin resin used for the base material layer include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, polypropylene, and ethylene-propylene copolymer. Polymer (random copolymer and / or block copolymer), propylene-α-olefin copolymer, ethylene-ethyl (meth) acrylate copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-n-butyl A (meth) acrylate copolymer, an ethylene-vinyl acetate copolymer, etc. can be mentioned. These may be used alone or in combination. The α-olefin is not particularly limited as long as it can be copolymerized with propylene. For example, butene-1, hexene-1, 4-methylpentene-1, octene-1, pentene-1, heptene-1 Etc.

  Although the manufacturing method of the surface protection film in this invention is not specified in particular, well-known methods, such as an inflation method and a T-die method, can be used. In the present invention, the T-die method is preferably used from the viewpoint of excellent thickness accuracy and control of surface roughness. As a method for forming a composite film of a release layer and a base material layer, the release layer and the base material layer are individually melt-extruded and then laminated and integrated in a die, and the release layer and the base material layer are laminated. A method of forming a film can be used.

  As a lamination thickness ratio of the release layer and the base material layer, the release layer / base material layer = 1/40 to 1/1 is preferable, and the release layer / base material layer = 1/20 to 1/2 is more preferable. It is. When the lamination thickness ratio is smaller than the above, the unwinding tension becomes high. When the lamination thickness ratio is larger than the above, there is a problem that the film forming property is deteriorated and the fish eyes are increased.

  The base material layer may contain fillers such as talc, stearamide, calcium stearate, lubricants, antioxidants, ultraviolet absorbers, pigments, antistatic agents, nucleating agents, etc., as long as the physical properties are not impaired. You may add suitably. Moreover, you may add these individually or in combination of 2 or more types.

  Moreover, you may give embossing, coloring by pigment addition, and printing to a mold release layer and a base material layer as needed.

  In the surface protective film of the present invention, examples of the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a polyvinyl ether-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive. Can do. As for the surface protection film of this invention, it is more preferable that an adhesion layer consists of an acrylic adhesive at least.

In a preferred example of the surface protective film of the present invention, a block copolymer represented by the general formula A-B-A or A-B (where A is a styrenic polymer block, and B is butadiene) Examples thereof include a rubber-based pressure-sensitive adhesive containing a polymer block, an isoprene polymer block, or an olefin polymer block obtained by hydrogenating them, and an acrylic pressure-sensitive adhesive.
In the block copolymer represented by the general formula A-B-A or A-B, the styrenic polymer block A has a weight average molecular weight of about 12,000 to 100,000 and a glass transition point of 20 ° C. or higher. Those are preferred. Also, the butadiene polymer block, the isoprene polymer block, or the olefin polymer block B obtained by hydrogenating these, has a weight average molecular weight of about 10,000 to 300,000 and a glass transition point of −20 ° C. or less. Those are preferred.

  The weight ratio of the A component to the B component is A / B = 5/95 to 50/50, more preferably A / B = 10/90 to 30/70. The block copolymer represented by the general formula A-B-A or A-B may be used alone or in combination of two or more.

  Specific examples of the block copolymer represented by the general formula A-B-A include styrene-ethylene / propylene-styrene, styrene-ethylene / butylene-styrene, and hydrogenated products thereof. Specific examples of the block copolymer represented by the general formula AB include styrene-ethylene / propylene, styrene-ethylene / butylene and hydrogenated products thereof.

  The block copolymer represented by the general formula A-B-A or AB may be used alone, but preferably a tackifying resin may be used as appropriate.

  Tackifying resins include aromatic hydrocarbon resins, aliphatic hydrocarbon resins, terpene resins, terpene phenol resins, aromatic hydrocarbon modified terpene resins, chroman indene resins, styrene resins, rosin resins, phenol resins Xylene resin or the like can be used, but this is not a limitation.

  The tackifying resin is appropriately selected from the viewpoints of compatibility with the block copolymer, the melting point of the resin, and the adhesive strength of the adhesive layer.

  The addition amount of the tackifying resin is preferably 5 to 200 parts, more preferably 5 to 100 parts with respect to 100 parts by weight of the block copolymer. If the addition amount of the tackifying resin is too small, there is a problem that the surface protective film is lifted or peeled off when it is bonded to an uneven adherend. If the addition amount is too large, the unwinding tension is high. Therefore, there is a problem that wrinkles and scratches occur when the substrate is bonded to the adherend. Moreover, the bleed-out of tackifying resin occurs, and the adhesive force tends to decrease.

  Specific examples of the acrylic resin-based pressure-sensitive adhesive include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobutyl (meth) acrylate, and hexyl (meth). Alkyl (meth) acrylates such as acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate; alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate and butoxyethyl (meth) acrylate ; (Meth) acrylates such as cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, vinyl acetate, (meth) acrylamide, N-methylol (meth) acrylamide, etc. Amides, styrene, acrylonitrile, vinyl pyridine, vinyl pyrrolidone, vinyl alkyl ethers, and the like can be mentioned homopolymer or copolymer and the like, not limited.

  The acrylic pressure-sensitive adhesive is preferably used by copolymerizing an acrylic monomer having a functional group. Examples of the acrylic compound having a functional group include unsaturated acids such as maleic acid, fumaric acid and (meth) acrylic acid; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- Examples thereof include, but are not limited to, hydroxyhexyl (meth) acrylate, dimethylaminoethyl methacrylate, (meth) acrylamide, N-methylol (meth) acrylamide, glycidyl (meth) acrylate, and maleic anhydride.

  The copolymerization method used in the present invention can be obtained by a method such as radical polymerization, but is not particularly limited.

  A crosslinking agent can be used for the acrylic pressure-sensitive adhesive as necessary. The cross-linking agent in the present invention is a compound that undergoes a heat cross-linking reaction with a functional group present in the copolymer, and finally forms an adhesive layer having a three-dimensional network structure. It is added to improve the property, solvent resistance, water resistance and the like. Examples of the crosslinking agent include isocyanate compounds, melamine compounds, urea compounds, epoxy compounds, amino compounds, amide compounds, aziridine compounds, oxazoline compounds, silane coupling agents, and modified products thereof. It can be used as appropriate.

  In the present invention, it is preferable to use an isocyanate compound and a modified product thereof in view of the crosslinkability and toughness of the adhesive layer. Isocyanate compounds are those having two or more isocyanate groups in one molecule, and are roughly classified into aromatic and aliphatic compounds. As the aromatic compound, tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, naphthalene diisocyanate, tolidine diisocyanate, paraphenylene diisocyanate, etc. are used, and as the aliphatic compound, hexamethylene diisocyanate, isophorone. Diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, tetramethylxylene diisocyanate, xylylene diisocyanate and the like are used. Examples of modified products of these isocyanate compounds include compounds such as a biuret, isocyanurate, and trimethylolpropane adduct of isocyanate compounds. These crosslinking agents may be used alone or in combination of two or more. Moreover, in order to accelerate | stimulate reaction as needed, crosslinking catalysts, such as a dibutyltin laurate, can be added to an adhesive.

  In addition, a tackifier resin, a softening agent, an anti-aging agent, a filler, a colorant such as a dye or a pigment, and the like can be added to the adhesive layer as necessary.

  Examples of tackifying resins include rosin resins, terpene phenol resins, terpene resins, aromatic hydrocarbon modified terpene resins, petroleum resins, coumarone / indene resins, styrene resins, phenol resins, xylene resins, and the like. But this is not the case.

  Examples of the softener include process oil, liquid rubber, and plasticizer.

  Examples of the filler include barium sulfate, talc, calcium carbonate, mica, silica, and titanium oxide.

  In the surface protective film of the present invention, the adhesive strength of the adhesive layer is preferably 2.0 to 30 N / 50 mm, and particularly preferably 3.0 to 20 N / 50 mm with respect to the acrylic plate. When the adhesive strength is lower than 2.0 N / 50 mm, there is a problem that the surface protective film is lifted or peeled when bonded to an uneven adherend, and when the adhesive strength is higher than 30 N / 50 mm, There is a problem that the unwinding tension becomes high, and wrinkles and scratches occur when bonding to the adherend.

  The thickness of the adhesive layer is 1.0 to 50 μm, preferably 2.0 to 30 μm. When the adhesive layer is thinner than 1.0 μm, there is a problem that the surface protective film is lifted or peeled off due to the low adhesive force. When the adhesive layer is thicker than 50 μm, the adhesive layer is unwound due to the high adhesive force. There is a problem that the tension becomes high and wrinkles and scratches occur when the substrate is bonded to the adherend. Moreover, since the stiffness of the surface protective film becomes strong, there is a problem that the handleability is deteriorated.

  The pressure-sensitive adhesive force of the pressure-sensitive adhesive layer of the present invention to the release layer surface is preferably 1.0 N / 50 mm or less, and more preferably 0.5 N / 50 mm or less. When the adhesive strength of the adhesive layer to the release layer surface exceeds 1.0 / 50 mm, the adhesive layer and the release layer surface of the film block when unrolling and using the surface protective film wound in a roll shape. Therefore, the unwinding tension becomes high and the unwinding property is deteriorated.

  Although it does not specify in particular as a formation method of the adhesion layer, the method of forming by the coextrusion method and the method of forming by the coating method can be mentioned as an example.

  In the surface protective film of the present invention, a method of forming an adhesive layer by a coating method is more preferable from the viewpoint of the adhesive strength of the adhesive layer. Various methods can be used as the method for forming the adhesive layer without any particular limitation. For example, an air knife coater, blade coater, bar coater, gravure coater, roll coater, curtain coater, die coater, knife coater, screen coater. , Mayer bar coaters, kiss coaters and the like.

  When forming the adhesive layer by a coating method, a solvent can be used as necessary. The type of the solvent is not particularly limited, but a solvent having a boiling point of 70 to 150 ° C. is easy to use from the viewpoints of workability during coating, drying before and after curing, and the like. Specific examples include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate and butyl acetate, either alone or in some cases. can do.

  After forming the adhesive layer by a coating method, the curing may be performed at a high temperature as necessary, or radiation such as ultraviolet rays may be applied to advance the reaction.

  Further, the surface of the release layer or the surface of the intermediate layer in contact with the adhesive layer is subjected to surface treatment or undercoating treatment, so that not only the coating property is improved but also the adhesiveness is improved, so that it can be used more preferably. . As the surface treatment of the surface of the release layer or the intermediate layer in contact with the adhesive layer, a known method such as corona discharge treatment (in air, nitrogen, carbon dioxide gas, rare gas, etc.) or plasma (glow discharge) treatment ( High pressure, low pressure), flame treatment, and high-frequency sputter etching treatment.

  The surface protective film of the present invention is particularly preferably used for a molded product having irregularities such as prism processing, embossing, and mat processing, etc., on the surface by molding or the like.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

  In the examples and comparative examples, the number of parts indicates the weight of the solid content, and% is based on the weight unless otherwise specified.

  The characteristic values of the present invention in Examples and Comparative Examples are based on the test methods shown below.

Test method (1) Adhesive strength Preparation of Sample A surface protective film (60 mm width × 120 mm length) was bonded to an adherend that had been cut in advance to 50 mm width × 100 mm length by reciprocating a 5 kg hand rubber roller. The surface protective film was cut according to the width of the adherend, and allowed to stand at 23 ° C. × 65% RH for 20 hours or more to prepare a sample.

B. Measuring method Using a tensile and compression tester TG-500N (Minebea Corp.), the integrated average value of the peel force when the surface protective film is peeled at a peeling angle of 180 ° and at a predetermined speed is the adhesive force (mN / 50 mm) did. The peeling speed was usually 300 mm / min, and the test length was 100 mm. The adhesive strength when the adherend was an acrylic plate was taken as the adhesive strength against the acrylic plate, and the adhesive strength when the adherend was a release layer surface was taken as the adhesive strength against the release layer surface. Further, the appearance of the release layer after the peel test was observed.

(2) Surface Roughness After performing a vapor deposition process on the release layer surface, a measurement length of 736 is measured with a non-contact type three-dimensional surface roughness meter WYKO NT-1000 (manufactured by Biko Japan) according to JIS B0601 (2001). The center line average roughness Ra (nm) was determined using (film lateral direction) × 480 (film longitudinal direction) as a measurement range.

(3) MFR (melt mass flow rate) of resin
Based on JIS K7210 (1999), MFR (g / 10min) under 230 degreeC and 2.16kgf / cm < ² > was calculated | required.

(Example 1)
As the resin composition for the release layer, graft type polypropylene-silicone mixture BY27-201 (manufactured by Toray Dow Corning Co., Ltd.) 30%, MFR 2 g / 10 min, with MFR 5/10 min and silicone resin content 40% A resin composition comprising 70% of an ethylene-propylene block copolymer was uniformly mixed with a Henschel mixer. As a resin composition for an intermediate layer, a resin composition comprising 100% of an MFR 2 g / 10 min ethylene-propylene block copolymer was uniformly mixed with a Henschel mixer.

  Next, using a T-die type composite film forming machine having a die width of 300 mm each having two extruders each having a diameter of 35 mm, the prepared resin composition is introduced into each extruder, and the thickness of the release layer / intermediate layer Adjust the discharge rate of each extruder so that the ratio is 1/4, extrude from a composite T die at an extrusion temperature of 210 ° C., subject the surface layer of the intermediate layer to corona treatment, and then a two-layer laminated film with a film thickness of 40 μm Was formed.

  Furthermore, 500 parts of toluene, 25 parts of tackifier resin (Arcon P-125 (Arakawa Chemical Industries, Ltd.)), 100 parts of block copolymer (Kraton G-1657 (Clayton Polymer Japan Co., Ltd.)) are sequentially added. In addition, a rubber adhesive having a concentration of 20% prepared by stirring for 1 hour was applied to the corona-treated surface of the film and dried in a hot air oven at 80 ° C. for 1 minute to form an adhesive layer having a thickness of 5 μm. The evaluation results are shown in Table 1.

(Example 2)
The same as Example 1, except that the graft type polypropylene-silicone mixture was 10% and the ethylene-propylene block copolymer was 90%.

(Example 3)
The same as Example 1, except that the graft type polypropylene-silicone mixture was 4% and the ethylene-propylene block copolymer was 96%.

Example 4
Release type resin composition MFR 15g / 10min, silicone resin content 50% oil type polypropylene-silicone mixture BY27-001 (Toray Dow Corning Co., Ltd.) 10%, ethylene-propylene block co Same as Example 1 except 90% polymer.

(Example 5)
Prepare an adhesive layer by adding 400 parts of ethyl acetate, 100 parts of acrylic adhesive Nissetsu KP-1405 (manufactured by Nippon Polycarbonate Kogyo Co., Ltd.) and 0.5 part of isocyanate crosslinking agent Nissetsu CK-102 in this order, and stirring for 10 minutes. The same procedure as in Example 1 was conducted except that the acrylic pressure-sensitive adhesive having a concentration of 20% was used and aging was performed at 40 ° C. for 4 days after the formation of the adhesive layer.

(Comparative Example 1)
The same as Example 1, except that the release layer resin composition was 100% ethylene-propylene block copolymer.

(Comparative Example 2)
The resin composition for the release layer was the same as that of Example 1 except that 90% ethylene-propylene block copolymer and 10% silica fine particles having an average particle diameter of 15 μm were used.

  From Table 1, the surface protective film of the present invention contains a silicone compound in the release layer and has a surface roughness Ra in the range of 250 to 5,000 nm as compared with Comparative Example 1. It can be seen that, while having a high adhesive force to the film, it has a low mold release coefficient and an excellent unwinding property. Moreover, although the comparative example 2 is excellent in unwinding property, since it comes off of silica fine particles, it turns out that it is not preferable compared with the surface protection film of this invention.

FIG. 1 is a cross-sectional view illustrating the surface protective film of the present invention. FIG. 2 is a cross-sectional view illustrating the surface protective film of the present invention.

Explanation of symbols

1: Release layer 2: Adhesive layer 3: Intermediate layer

Claims (12)

  An adhesive layer is laminated on one side, and a release layer is laminated on the other side. The release layer contains at least a polyolefin resin and a silicone compound, and its surface roughness Ra is in the range of 250 to 5,000 nm. the film.   The surface protection film according to claim 1, wherein a release layer is formed on one side of a base material layer made of polyolefin resin by a co-extrusion method, and an adhesive layer is formed on the opposite side.   The surface protective film according to claim 1 or 2, wherein the adhesive force of the adhesive layer to the acrylic plate is 2.0 to 30 N / 50 mm, and the release factor R is 0.25 or less.   The polyolefin resin of the release layer is at least one selected from polyethylene resin, polypropylene resin, ethylene-propylene copolymer, and propylene-α-olefin copolymer. Surface protective film.   The surface protective film according to any one of claims 1 to 4, wherein the silicone compound of the release layer comprises a polypropylene-silicone mixture in which a silicone resin is uniformly dispersed in a polypropylene resin.   The surface protective film according to any one of claims 1 to 5, wherein the polypropylene-silicone mixture is formed by graft polymerization of a reactive polyorganosiloxane to a polypropylene resin.   The surface protection film according to claim 6, wherein the content of the silicone resin in the release layer is 0.1 to 30%.   Block copolymer in which the adhesive layer is represented by at least the general formula A-B-A or A-B (wherein, A is a styrene polymer block, B is a butadiene polymer block, isoprene polymer block) Or an olefin polymer block obtained by hydrogenating them.) The rubber adhesive comprising 100 parts by weight and 5 to 200 parts of tackifying resin. Surface protective film.   The surface protective film according to claim 1, wherein the adhesive layer comprises at least an acrylic adhesive.   The surface protective film according to claim 1, wherein the adhesive layer is formed by a coating method.   The manufacturing method of the surface protection film which manufactures a surface protection film by the method in any one of Claims 1-10.   A molded product obtained by adhering a surface protective film produced by the production method according to claim 11 to the surface.

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