WO2010084832A1

WO2010084832A1 - Surface protective film

Info

Publication number: WO2010084832A1
Application number: PCT/JP2010/050463
Authority: WO
Inventors: 一範小橋; 芳隆佐藤; 達彦薄井
Original assignee: Dic株式会社
Priority date: 2009-01-21
Filing date: 2010-01-18
Publication date: 2010-07-29
Also published as: JPWO2010084832A1; TW201033322A

Abstract

Disclosed is a surface protective film used for the purpose of protecting the surfaces of various types of resin plates, glass plates, or metal plates used in the fields of building materials and electrics/electronics. The film is adhered to the surfaces of the same in order to protect the adherends from scratches and/or contamination during storage, transportation, and subsequent processing. More specifically, provided is a surface protective film with which a resin prepared by mixing three components, namely, a styrene-based elastomer or a block copolymer having specific crystalline olefin blocks, an amorphous α-olefin-based polymer, and a crystalline olefin-based polymer, at a specific ratio is used as the resin for the adhesive layer of the surface protective film. Thus, good adhesion is demonstrated, even on an adherend with an uneven surface, and handling ability is excellent.

Description

Surface protection film

The present invention is applied to the surface of various optical films, various resin plates, glass plates, metal plates and the like used in the electric / electronic field, building materials, etc., and is stored, transported and post-processed. It is related with the surface protection film which protects a to-be-adhered body from a contamination | contamination etc. in the case of. In particular, the present invention relates to a surface protective film that exhibits good tackiness even when the adherend surface is uneven and has good handling properties.

The basic required performance for the surface protective film includes excellent adherence workability that can be uniformly applied to the above-mentioned various adherends without involving wrinkles or air, storage of the adherend, transportation, etc. Adhesive strength that does not float or peel between the surfaces of the adherend, environmental changes during storage of the adherend, and changes in the adhesive strength over time due to post-processing are less likely to be easily peeled off and the surface of the adherend after peeling And so on.

As a conventional surface protection film, a film made of polyvinyl chloride resin, polyethylene resin, polypropylene resin, etc. is used as a base material, and one surface thereof is coated with an adhesive such as urethane, acrylic or rubber. Are known. However, these surface protective films sometimes have poor adhesion between the base film and the pressure sensitive adhesive, or when peeled from the adherend due to the low cohesive strength of the pressure sensitive adhesive itself. There is a problem that a part of the film remains on the surface of the adherend. In addition, the surface protection film produced by applying a pressure-sensitive adhesive to the film requires a minimum of two steps, ie, a film production process and a pressure-sensitive adhesive coating process, which increases the production cost. There is a problem that a large amount of solvent needs to be removed in the pressure-sensitive adhesive coating process, which increases the environmental load.

As a method for improving the above problems, a self-adhesive surface protective film in which a base film layer and an adhesive layer are simultaneously extruded and laminated by a coextrusion lamination method has been proposed. Such a surface protective film has, for example, an adhesive layer made of a resin composition containing 10 to 50 parts by mass of a polyethylene resin with respect to 100 parts by mass of a hydrogenated product of a styrene-conjugated diene polymer. An adhesive film is provided (see, for example, Patent Document 1).

However, the surface protective film provided in Patent Document 1 has a problem in that the adhesive force with respect to the surface of the adherend may be insufficient.

Japanese Patent Laid-Open No. 2007-161882

The problem to be solved by the present invention is that the substrate layer has a practical adhesive force for an adherend having an uneven surface, and is wound up into a roll shape and then used again after being unrolled. It is to provide a surface protective film having good handling properties in which the adhesive layer and the pressure-sensitive adhesive layer are in close contact with each other and so-called blocking does not occur, and the surface of the adherend after peeling is small in glue residue.

As a result of intensive studies to solve the above problems, the present inventors have found that a block copolymer having a styrenic elastomer or a specific crystalline olefin block in the adhesive layer of the surface protective film, and an amorphous α- Using a resin in which three components, an olefin polymer and a crystalline olefin polymer, are mixed at a specific blending ratio, practical adhesion can be achieved even when the surface of the adherend is uneven. The present inventors have found that a surface protective film having good strength, small adhesive residue on the adherend surface after blocking and peeling, and good handleability can be obtained, and the present invention has been completed.

That is, this invention is a surface protection film which has a base material layer (A) and an adhesion layer (B), Comprising: This adhesion layer (B) is random of a styrene-type polymer block, styrene, and a conjugated diene compound. Copolymer (B1-1) having a styrene random copolymer block obtained by hydrogenating the double bond portion of the copolymer, a formula aba, or ab (a is a styrene polymer) A block, and b is a styrene block copolymer (B1-2) represented by a conjugated diene polymer block or an olefin polymer block obtained by hydrogenating double bonds in a conjugated diene polymer) Or a block copolymer (B1-3) comprising a crystalline olefin polymer block obtained by hydrogenation of a conjugated diene polymer block and a conjugated diene polymer block, and an amorphous α Provided is a surface protective film comprising as a main component a mixture of 5 to 45% by mass of an olefin polymer (B2) and 5 to 45% by mass of a crystalline olefin polymer (B3). To do.

The surface protective film of the present invention is a time-dependent change in adhesive force even if it is exposed to a high-temperature environment after being attached to an optical film, various resin plates, a glass plate, a metal plate, etc. whose surface is uneven. And has excellent heat resistance, such as no lifting or peeling from the adherend, and no warpage of the adherend, and there is no adhesive residue visible on the adherend surface after peeling. Furthermore, after winding in a roll shape, there is no blocking at the time of extending and using again, and it is excellent also in blocking resistance.

Hereinafter, the present invention will be described in detail. The surface protective film of the present invention is a multilayer film having at least a base material layer and an adhesive layer.

The resin used for the substrate layer (A) of the surface protective film in the present invention is not particularly limited, but it is preferable to use an olefin polymer as a main component, for example, a propylene homopolymer, a propylene-ethylene copolymer, Examples thereof include propylene polymers such as propylene-ethylene-butene-1 copolymer, ethylene polymers such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene. These olefin polymers may be used alone or in combination of two or more. Among these, the surface protective film of the present invention is applied to various optical films, resin plates, glass plates, metal plates, etc., and then subjected to post-processing such as drying and heat molding to be exposed to a high temperature environment. In the case of use in a case where the material is wound in a roll and stored for a long period of time, it is preferable to use a crystalline propylene polymer, and it is more preferable to use a propylene homopolymer in terms of improving the heat resistance of the surface protective film. preferable. In the present application, crystallinity means having a peak of 0.5 J / g or more in the range of 95 to 250 ° C. in DSC (differential scanning calorimetry).

The propylene polymer has a melt flow rate (hereinafter referred to as “230 ° C. MFR”; a value measured at 230 ° C. and 21.18 N in accordance with JIS K7210: 1999) of 0.5 to Those having a melting point of 120 to 165 ° C. at 30.0 g / 10 min are preferred, more preferably those having an MFR of 230 to 120 ° C. of 2.0 to 15.0 g / 10 min and a melting point of 125 to 162 ° C. is there. If the MFR and the melting point are within this range, the film is less shrunk even if it is exposed to a high temperature environment by drying, heat molding or the like after being attached to the adherend, so that it does not float or peel off. There is no warping, and the film formability of the laminated film is improved.

On the other hand, among the above (A), when the adherend is cut with the surface protective film adhered to the adherend, the surface protective film is cut cleanly, resulting in poor appearance such as stringing and fluffing. It is preferable to use an ethylene polymer in terms of cutting ability that does not occur, and it is more preferable to use a mixed resin of low density polyethylene and high density polyethylene in terms of good heat resistance.

The ethylene polymer has a melt flow rate (hereinafter referred to as “190 ° C. MFR”; a value measured at 190 ° C. and 21.18 N in accordance with JIS K7210: 1999) of 0.5 to It is preferable that it is 30.0 g / 10 min since the extrusion is easy, and more preferable is that the MFR at 190 ° C. is 2.0 to 15.0 g / 10 min. Further, these ethylene polymers preferably have a melting point of 90 to 135 ° C, and more preferably have a melting point of 105 to 130 ° C. If the melting point is within this range, since the film shrinks less even when placed in a high temperature environment by drying, thermoforming, etc. after being attached to the adherend, the adherend is lifted or peeled off. Can be suppressed.

In the present application, “main component” means that, in each layer, the specific resin or mixture thereof has a mass ratio of the specific resin or mixture thereof to 65% by mass or more, preferably 80% by mass. That's it.

The pressure-sensitive adhesive layer (B) of the surface protective film of the present invention is a styrenic polymer block in order to balance the conformity to unevenness of the adherend surface with the reduction of adhesive residue after peeling and prevention of blocking. And a copolymer (B1-1) having a styrene random copolymer block obtained by hydrogenating a double bond portion of a random copolymer of styrene and a conjugated diene compound, a general formula aba, or Styrene represented by ab (a is a styrenic polymer block, and b is a conjugated diene polymer block or an olefin polymer block obtained by hydrogenating a double bond in a conjugated diene polymer) Block copolymer (B1-2), or a block copolymer comprising a crystalline olefin polymer block obtained by hydrogenating a conjugated diene polymer block and a conjugated diene polymer block ( 1-3), 50 to 85% by mass of amorphous α-olefin polymer (B2), 5 to 45% by mass, and 5 to 45% by mass of crystalline olefin polymer (B3). It is essential to use as a main component.

Examples of the conjugated diene compound used as a raw material for the copolymer (B1-1) or the styrene block copolymer (B1-2) include 1,3-butadiene, isoprene, 2,3-dimethyl-1, Examples include 3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene, and the like. From the viewpoint of availability, 1,3-butadiene and isoprene are preferably used. Examples of the styrene compound forming the styrene polymer block include styrene, α-methyl styrene, P-methyl styrene, t-butyl styrene, divinyl benzene, 1.1-diphenyl styrene, N, N-dimethyl. -P-aminomethylstyrene N, N-diethyl-P-aminoethylstyrene and the like can be mentioned, and styrene is preferably used.

When using the copolymer (B1-1) or the styrene block copolymer (B1-2), from the viewpoint of excellent followability to finer surface irregularities, the styrene compound in the copolymer The mass ratio of the derived structure / conjugated diene compound-derived structure is preferably in the range of 5/95 to 60/40.

The block copolymer (B1-3) includes a crystalline olefin polymer block (I) obtained by hydrogenating a conjugated diene polymer block and a conjugated diene polymer block (II) (I-II) _n1 Or (I-II) _n2- (I) (n1, n2 is an integer of 1 or more), wherein at least one terminal of the polymer chain is composed of the crystalline olefin polymer block (I). Preferably there is.

Examples of such a block copolymer (B1-3) include those provided in JP-A-3-128957 and JP-A-8-231786. Specifically, a polybutadiene polymer block having a low 1,2-vinyl bond content (for example, 25% or less) and a polymer mainly composed of a conjugated diene compound, which contains 1,2- and 3,4-bonds. A copolymer composed of a polymer block having a high rate (for example, 50% or more) is synthesized, and the polybutadiene portion is made to have a structure similar to polyethylene by hydrogenating the copolymer to form a crystalline polymer block. And the like.

The conjugated diene compound used as a raw material for the block copolymer (B1-3) is the same as the conjugated diene compound used for the copolymer (B1-1) or the styrene block copolymer (B1-2). Any of these may be exemplified, and 1,3-butadiene and isoprene are preferably used from the viewpoint of industrial availability.

Examples of commercially available products include “Dynalon 1320P” manufactured by JSR Corporation, which is a styrene-butadiene random copolymer hydrogenated product (hereinafter abbreviated as HSBR) as the copolymer (B1-1). Also, as the styrene block copolymer (B1-2), “SIS5200” manufactured by JSR Corporation, which is a styrene-isoprene-styrene block copolymer (hereinafter abbreviated as SIS), a styrene-ethylene-butylene-styrene block. Kuraray Stock Co., Ltd., which is a copolymer (hereinafter abbreviated as SEBS) “Dynalon 8600P, Dynalon 8601P” manufactured by JSR Corporation, and a styrene-ethylene-propylene-styrene block copolymer (hereinafter abbreviated as SEPS). “Septon 2063, Septon 2004”, etc. The block copolymer (B1-3) is a block copolymer having a structure of crystalline olefin-ethylene / butylene copolymer-crystalline olefin (hereinafter abbreviated as CEBC) manufactured by JSR Corporation. “Dynalon 6200P” and the like.

The amorphous α-olefin polymer (B2) used for the pressure-sensitive adhesive layer (B) of the surface protective film of the present invention is a polymer containing monomer units based on α-olefins having 3 to 20 carbon atoms. In the differential scanning calorimeter (DSC) measurement range of −100 to 200 ° C., both a melting peak with a crystal heat of fusion of 1 J / g or more and a crystallization peak with a heat of crystallization of 1 J / g or more were observed. It is a polymer that is not.

The α-olefin having 3 to 20 carbon atoms may be linear or branched, for example, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 Nonene-1, decene-1, undecene-1, dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nanodecene-1, eicosene-1, etc. Linear α-olefin; branched such as 3-methylbutene-1,3-methylpentene-1,4-methylpentene-1,2-ethyl-1-hexene, 2,2,4-trimethylpentene-1 These α-olefins are included. The amorphous α-olefin polymer (B2) is preferably a polymer containing two or more of these α-olefins, and includes a monomer unit based on propylene and an α-olefin having 4 to 20 carbon atoms. A polymer containing one or more monomer units based on it is more preferred. Further, the amorphous α-olefin polymer (B2) may contain a monomer other than the α-olefin. Examples of such monomers include ethylene, polyene compounds, cyclic olefins, vinyl aromatic compounds, and the like. Among the amorphous α-olefin polymers (B2), amorphous propylene-butene-1 copolymers and amorphous propylene-ethylene-butene-1 copolymers are preferable. These may be used alone or in combination of two or more.

The monomer unit based on propylene in the amorphous propylene-butene-1 copolymer is 70% by mass when the total monomer unit of the amorphous propylene-butene-1 copolymer is 100% by mass. The above is preferable, More preferably, it is 80 mass% or more, More preferably, it is 90 mass% or more. When the monomer unit based on propylene is within this range, the heat resistance is improved.

The monomer unit based on propylene in the amorphous propylene-ethylene-butene-1 copolymer is 100% by mass based on the total monomer units of the amorphous propylene-ethylene-butene-1 copolymer. , 50% by mass or more, preferably 60% by mass or more. When the monomer unit based on propylene is within this range, the heat resistance is improved. The monomer unit based on ethylene in the amorphous propylene-ethylene-butene-1 copolymer is preferably 10% by mass or more, more preferably 20% by mass or more. If the monomer unit based on ethylene is in this range, the adhesive layer becomes relatively soft, and even if the adherend surface has irregularities, it adheres in a form that follows the irregularities. Power is obtained.

The intrinsic viscosity [η] of the amorphous α-olefin polymer (B2) is preferably in the range of 0.1 to 10.0 dl / g, more preferably 0.7 to 7.0 dl / g. g. Furthermore, the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is preferably more than 1 and 4 or less, more preferably 2 to 3. . When the intrinsic viscosity and molecular weight distribution of the amorphous α-olefin polymer (B2) are in this range, the heat resistance, transparency and adhesiveness are improved, and the adherend with the surface protective film attached is stored for a long time. Even when exposed to a high temperature environment, the low molecular weight component in the amorphous α-olefin polymer (B2) does not migrate to the adherend surface and contaminate the adherend. In addition, since the amorphous α-olefin polymer (B2) is an olefin polymer, the alteration of the resin such as deacetic acid as in the case of using the ethylene-vinyl acetate copolymer for the adhesive layer is performed. Thus, there is no increase in adhesive strength over time, and stable adhesive strength can be maintained over a long period of time.

Examples of the method for producing the amorphous α-olefin polymer (B2) include a method of polymerizing with a metallocene catalyst using a gas phase polymerization method, a solution polymerization method, a slurry polymerization method, a bulk polymerization method, or the like. Can be mentioned. A more preferable production method includes the production method disclosed in JP-A-2002-348417.

Examples of the crystalline olefin polymer (B3) used for the adhesive layer (B) of the surface protective film of the present invention include propylene homopolymer, propylene-ethylene copolymer, propylene-ethylene-butene-1 copolymer, and the like. Examples include propylene-based polymers, low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene.

The propylene-based polymer preferably has an MFR of 230 ° C. of 0.5 to 30.0 g / 10 min and a melting point of 120 to 165 ° C., more preferably an MFR of 230 ° C. of 2. Those having a weight of 0 to 15.0 g / 10 min are preferred.

The ethylene polymer preferably has an MFR at 190 ° C. of 0.5 to 30.0 g / 10 min because of easy extrusion, and more preferably has an MFR at 190 ° C. of 2. 0 to 15.0 g / 10 min.

The pressure-sensitive adhesive layer (B) of the present invention comprises 50 to 85 masses of the copolymer (B1-1), the styrenic block copolymer (B1-2), or the block copolymer (B1-3). %, An amorphous α-olefin polymer (B2) of 5 to 45% by mass, and a crystalline olefin polymer (B3) of 5 to 45% by mass. When the blending ratio of the component (B1-1), (B1-2) or (B1-3) is less than 50% by mass, the adhesive strength of the protective film is insufficient, and when it exceeds 85% by mass, the protective film has tackiness. Is too strong, and there are problems such as difficulty in handling and generation of adhesive residue. Further, when the blending ratio of the component (B2) is less than 5% by mass or exceeding 45% by mass, there is a problem that the adherence having an uneven surface has insufficient adhesive force. Moreover, it can adjust to the adhesive force requested | required by adjusting the mixture ratio of a component (B3) within the said range.

The surface protective film of the present invention is composed of at least two layers of the base material layer (A) and the adhesive layer (B) as described above, and further on the base material layer (A) (surface having the adhesive layer). The surface layer (C) may be provided on the opposite surface). The resin used for the surface layer (C) is not particularly limited, but it is preferable to use an olefin polymer from the viewpoint of good affinity with the base material layer (A). Examples include linear low density polyethylene, medium density polyethylene, high density polyethylene, propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-butene-1-ethylene copolymer, and the like. Among these, low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, and propylene homopolymer are more preferable because the film formability of the laminated film is improved.

Further, the resin used for the surface layer (C) may be a mixed resin of the above-mentioned resins and a propylene-ethylene block copolymer as a main component, and the surface of the surface layer may be modified into a satin finish. By making the surface of the surface layer into a satin finish, it is possible to reduce blocking when stored in a roll shape, which is likely to occur when the adhesive strength is designed strongly. Here, the propylene-ethylene block copolymer is a resin obtained by block polymerization of propylene and ethylene, and any resin can be used as long as the surface of the resin layer becomes satin when used in the surface layer (C). There is no particular limitation. Examples thereof include a propylene-ethylene block copolymer obtained by polymerization of ethylene or ethylene and propylene in the presence of a polypropylene homopolymer. Among these, it is preferable to use a propylene-ethylene block copolymer having an ethylene-derived component content of 8 to 20% by mass because the surface can be easily made into a satin-like surface. Is preferably a propylene-ethylene block copolymer of 10 to 15% by mass. Further, the MFR at 230 ° C. of the mixed resin with the propylene-ethylene block copolymer is preferably 4 to 12 g / 10 minutes from the viewpoint of easy extrusion, and more preferably 6 to 10 g / 10 minutes. The density is preferably 0.890 to 0.910 g / cm ³ , more preferably 0.895 to 0.905 g / cm ³ .

The surface protective film of the present invention preferably has a total film thickness of 20 to 120 μm. If the thickness of the entire film is within this range, the protection of the adherend, the adhesive property that does not cause floating or peeling during storage or transportation of the adherend, and the workability such as sticking / peeling are good. It becomes. The thickness of the adhesive layer (B) is preferably 3 to 30 μm, more preferably 5 to 25 μm. When the thickness of the pressure-sensitive adhesive layer (B) is within this range, the pressure-sensitive adhesive properties that do not float or peel off during storage, transportation, etc. of the adherend and the film formability of the laminated film are improved. Furthermore, when the surface layer (C) is provided on the surface protective film of the present invention, the thickness of the surface layer (C) is preferably 3 to 30 μm, more preferably 5 to 20 μm. When the thickness of the surface layer (C) is within this range, the heat resistance and the film formability of the laminated film are good.

The method for producing the surface protective film of the present invention is not particularly limited as long as it is a coextrusion lamination method. For example, the resin used for each resin layer is melted by using two or more extruders, Examples include a method of laminating in a molten state by a coextrusion method such as an extrusion die method or a feed block method, and then processing into a film using a method such as inflation or a T-die / chill roll method. In the case of the T-die / chill roll method, the melt-laminated film may be nipped between a rubber touch roll, a steel belt or the like and the chill roll and cooled.

Furthermore, the surface protective film of the present invention may be stretched in at least one axial direction. As the stretching method, various methods such as longitudinal or lateral uniaxial stretching, sequential biaxial stretching, simultaneous biaxial stretching, or tubular method biaxial stretching can be employed. Further, the stretching process may be inline or offline. As a stretching method for uniaxial stretching, a proximity roll stretching method or a rolling method may be used. The stretching ratio of uniaxial stretching is preferably 1.1 to 80 times in the longitudinal or transverse direction, more preferably 3 to 30 times. On the other hand, the stretching ratio of biaxial stretching is preferably 1.2 to 70 times in terms of area ratio, more preferably 4 to 6 times in length, 5 to 9 times in width, and 20 to 54 times in terms of area ratio.

Also, the longitudinal or lateral stretching process is not necessarily limited to one-stage stretching, and may be multi-stage stretching. In particular, in longitudinal uniaxial stretching such as longitudinal uniaxial roll stretching and longitudinal uniaxial rolling stretching in sequential biaxial stretching, it is preferable to perform multistage stretching in view of thickness, uniformity of physical properties, and the like. Further, in the proximity roll stretching, either the flat method or the cross method may be used, but multistage proximity cross stretching that can reduce width shrinkage is more preferable. The stretching temperature is preferably 80 to 160 ° C. in any stretching method in the case of uniaxial stretching, and preferably 90 to 165 ° C. in the case of using tenter stretching with uniaxial stretching. Further, more preferable stretching temperatures are 110 to 155 ° C. and 120 to 160 ° C., respectively. On the other hand, in the case of biaxial stretching, the stretching temperature range similar to that in the case of uniaxial stretching is preferable in any method. Moreover, you may provide a pre-heating part before an extending process, and a heat setting part after an extending process suitably. In this case, the temperature of the preheating part is preferably 60 to 140 ° C., and the temperature of the heat fixing part is preferably 90 to 160 ° C.

The surface protective film of the present invention is further stretched in at least uniaxial direction and structurally stabilized by heat setting, and further by orientation crystallization of the base material layer (A) mainly composed of an olefin polymer. The heat resistance is improved, and the change with time of the adhesive force is small, which is preferable.

In addition, a tackifier may be added as appropriate as long as the effects of the present invention are not impaired. 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 resins, terpene phenol resins, rosin resins such as polymerized rosin, phenol resins, xylene resins or hydrogenated products thereof, which are generally used for adhesives can be used without any particular limitation . These tackifiers may be used alone or in combination of two or more.

In addition, a lubricant, an antiblocking agent, an ultraviolet absorber, a light stabilizer, an antistatic agent, an antifogging agent, and the like may be added as appropriate as long as the effects of the present invention are not impaired. As these additives, it is preferable to use various additives for olefin polymers.

Hereinafter, the present invention will be specifically described with reference to examples and comparative examples.

(Synthesis example)
[Synthesis of Amorphous α-Olefin Polymer (Amorphous Propylene-Butene-1 Copolymer)]
In a 100L stainless steel polymerization vessel equipped with a stirrer, propylene and butene-1 were continuously copolymerized using hydrogen as a molecular weight regulator to produce amorphous propylene-butene as an amorphous α-olefin polymer. -1 copolymer was obtained. Specifically, hexane as a polymerization solvent is continuously supplied from the lower part of the polymerization vessel at a supply rate of 100 L / hour, propylene at 24.00 kg / hour, and butene-1 at 1.81 kg / hour. The reaction mixture was continuously withdrawn from the top of the reactor so that the reaction mixture in the polymerization vessel maintained 100 L. Further, from the lower part of the polymerization vessel, dimethylsilyl (tetramethylcyclopentadienyl) (3-t-butyl-5-methyl-2-phenoxy) titanium dichloride is added as a catalyst component at 0.005 g / hour at triphenylmethyl. Tetrakis (pentafluorophenyl) borate was continuously fed at a rate of 0.298 g / hr and triisobutylaluminum was fed at a rate of 2.315 g / hr. The copolymerization reaction was carried out at 45 ° C. by circulating cooling water through a jacket attached to the outside of the polymerization vessel. A small amount of ethanol was added to the reaction mixture continuously extracted from the upper part of the polymerization vessel to stop the polymerization reaction, followed by steps of demonomerization, water washing, and solvent removal. A polymer was obtained. Subsequently, the obtained copolymer was dried under reduced pressure at 80 ° C. for 24 hours. In this amorphous propylene-butene-1 copolymer, the content of propylene monomer units was 94.5% by mass, and the content of butene-1 monomer units was 5.5% by mass. Moreover, the melting peak in DSC of the copolymer was not observed, the intrinsic viscosity [η] was 2.3 dl / g, and the molecular weight distribution (Mw / Mn) was 2.2.

(Adjustment example)
[Preparation of Amorphous α-Olefin Polymer Composition]
The amorphous propylene-butene-1 copolymer obtained above was added to a crystalline propylene-butene-1 copolymer [density 0.900 g / cm ³ , MFR (230 ° C., 21.18 N) 10.0 g / 10 minutes, DSC maximum melting peak 126 ° C.) was blended so that amorphous propylene-butene-1 copolymer / crystalline propylene-butene-1 copolymer = 95/5 (mass ratio), Furthermore, an aromatic phosphite antioxidant (Irgafos 168 manufactured by Ciba Specialty Chemicals) and a hindered phenol antioxidant (Irganox 1010 manufactured by Ciba Specialty Chemicals) )) Is blended at 2000 ppm each, melt-kneaded with a twin screw extruder, and then amorphous α-olefin with a granulator A pellet of the polymer composition was obtained.

Example 1
As the resin for the surface layer, low density polyethylene [density: 0.902 g / cm ³ , MFR (190 ° C., 21.18 N): 4 g / 10 min; hereinafter referred to as “LDPE”. And a propylene-ethylene block copolymer in a mass ratio of 15/85, and a metallocene catalyst-based propylene-ethylene random copolymer [density: 0.900 g / cm ³ as a resin for the base layer] , MFR (230 ° C., 21.18 N): 7.0 g / 10 min, content of ethylene monomer unit: 3.5% by mass; hereinafter referred to as “COPP”. As a resin for the adhesive layer, 55 parts by mass of a hydrogenated product of a styrene / butadiene random copolymer (“Dynalon 1320P” manufactured by JSR Corporation, hereinafter referred to as “HSBR”) and the amorphous property prepared above are used. 35 parts by mass of α-olefin polymer composition and linear low density polyethylene [density: 0.920 g / cm ³ , MFR (190 ° C., 21.18 N): 3 g / 10 min; hereinafter referred to as “LLDPE”. ] Extruder for surface layer using a composition in which 10 parts by mass of a resin composition consisting of 10 parts by mass was blended with 10 parts by mass of an alicyclic petroleum resin (“Alcon P-125” manufactured by Arakawa Chemical Co., Ltd.) as a tackifier (Caliber 50 mm), substrate layer extruder (caliber 50 mm) and adhesive layer extruder (caliber 40 mm), respectively, by co-extrusion at an extrusion temperature of 250 ° C., the thickness of the surface layer from the T-die is 12 μm, Extrusion was performed so that the thickness of the base material layer was 36 μm and the thickness of the adhesive layer was 12 μm, and after cooling with a 40 ° C. water-cooled metal cooling roll, the film was wound on a roll to obtain a surface protective film. The obtained film was aged in a aging room at 35 ° C. for 48 hours in order to stabilize physical properties.

(Example 2)
As a resin for the adhesive layer, a composition comprising HSBR, an amorphous α-olefin polymer composition, and LLDPE, 10 parts by mass of Alcon P-125 per 100 parts by mass of a 65/25/10 mixture by mass ratio. A surface protective film of Example 2 was obtained in the same manner as Example 1 except that it was used.

(Example 3)
As a resin for the adhesive layer, a composition in which 10 parts by mass of Alcon P-125 is blended with 100 parts by mass of an 85/10/5 mixture of HSBR, an amorphous α-olefin polymer composition, and LLDPE. A surface protective film of Example 3 was obtained in the same manner as Example 1 except that it was used.

Example 4
As the adhesive layer resin, a styrene-ethylene / propylene-styrene block copolymer (“Septon 2063” manufactured by Kuraray Co., Ltd .; hereinafter referred to as “SEPS”), an amorphous α-olefin polymer composition, and LLDPE are used. A surface protective film of Example 4 was obtained in the same manner as in Example 1 except that a composition in which 10 parts by mass of Alcon P-125 was added to 100 parts by mass of a 55/35/10 mixture by mass ratio was obtained.

(Example 5)
As the adhesive layer resin, a composition in which 10 parts by mass of Alcon P-125 is blended with 100 parts by mass of a 65/25/10 mixture of SEPS, an amorphous α-olefin polymer composition, and LLDPE in a mass ratio. A surface protective film of Example 5 was obtained in the same manner as Example 1 except that it was used.

(Example 6)
As a resin for the adhesive layer, a styrene-isoprene block copolymer (“SIS5200” manufactured by JSR Corporation; hereinafter referred to as “SIS”), an amorphous α-olefin polymer composition, and LLDPE in a mass ratio of 55 / A surface protective film of Example 6 was obtained in the same manner as in Example 1 except that a composition in which 10 parts by mass of Alcon P-125 was mixed with 100 parts by mass of the 35/10 mixture was used.

(Example 7)
As a resin for the adhesive layer, a hydrogenated product of styrene-isobutylene block copolymer (“Sibstar 072T” manufactured by Kaneka Corporation; hereinafter referred to as “SIBS”), an amorphous α-olefin polymer composition, and LLDPE are used. A surface protective film of Example 7 was obtained in the same manner as in Example 1 except that a composition in which 10 parts by mass of Alcon P-125 was mixed with 100 parts by mass of a 55/35/10 mixture by mass ratio.

(Example 8)
As a resin for the adhesive layer, a mass ratio of a styrene-ethylene-butylene-styrene copolymer (manufactured by JSR Corporation; Dynalon 88601P; hereinafter referred to as “SEBS”), an amorphous α-olefin polymer composition, and LLDPE. A surface protective film of Example 8 was obtained in the same manner as in Example 1 except that a composition in which 10 parts by mass of Alcon P-125 was mixed with 100 parts by mass of the 55/35/10 mixture was used.

Example 9
As a resin for the adhesive layer, a crystalline olefin-ethylene / butylene copolymer-crystalline olefin block copolymer (manufactured by JSR Corporation; Dynalon 6200P, hereinafter referred to as “CEBC”) and an amorphous α-olefin polymer. Surface protection of Example 9 in the same manner as in Example 1 except that a composition in which 10 parts by mass of Alcon P-125 was blended with 100 parts by mass of a 55/40/5 mixture by weight with LLDPE was used. A film was obtained.

(Example 10)
As the resin for the base layer, high density polyethylene [density: 0.96 g / cm ³ , MFR (190 ° C., 21.18 N): 13 g / 10 min; hereinafter referred to as “HDPE”. ] And LDPE were used in the same manner as in Example 1 except that 50/50 was mixed and used to obtain a surface protective film of Example 10.

Example 11
A surface protective film of Example 11 was obtained in the same manner as Example 5 except that HDPE / LDPE was mixed and used at a mass ratio of 50/50 as the base layer resin.

(Example 12)
A surface protective film of Example 12 was obtained in the same manner as in Example 6 except that HDPE / LDPE was mixed and used at a mass ratio of 50/50 as the base layer resin.

(Comparative Example 1)
Comparative Example 1 was carried out in the same manner as in Example 1 except that as the adhesive layer resin, a composition in which 10 parts by mass of Alcon P-125 was blended with 100 parts by mass of 85/15 mixture of HSBR and LLDPE was used. A surface protective film was obtained.

(Comparative Example 2)
As a resin for the adhesive layer, a composition comprising HSBR, an amorphous α-olefin polymer composition, and LLDPE blended with 10 parts by mass of Alcon P-125 with respect to 100 parts by mass of a 40/50/10 mixture by mass ratio. A surface protective film of Comparative Example 2 was obtained in the same manner as Example 1 except that it was used.

(Comparative Example 3)
As a resin for the adhesive layer, a composition in which 10 parts by mass of Alcon P-125 is blended with 100 parts by mass of a 90/3/7 mixture of HSBR, an amorphous α-olefin polymer composition, and LLDPE in a mass ratio. A surface protective film of Comparative Example 3 was obtained in the same manner as Example 1 except that it was used.

(Comparative Example 4)
Comparative Example 4 was carried out in the same manner as in Example 1 except that a composition in which 10 parts by mass of Alcon P-125 was blended with 100 parts by mass of a mixture of SEPS and LLDPE in a mass ratio of 85/15 was used as the adhesive layer resin. A surface protective film was obtained.

(Comparative Example 5)
As the base layer resin, HDPE / LDPE is mixed and used at a mass ratio of 50/50, and as the adhesive layer resin, Alcon P- is used with respect to 100 parts by mass of the HSBR / LLDPE = 85/15 mixture. The surface protection film of Comparative Example 5 was obtained in the same manner as in Example 1 except that the composition containing 125 parts by mass of 125 was used.

The following measurements and evaluations were performed using the surface protective films obtained in Examples 1 to 11 and Comparative Examples 1 to 5 described above.

(1) Measurement of adhesive strength In a temperature-controlled room at 23 ° C. and 50% RH, the surface protective film was formed with a convex surface (convex pitch 25 μ, tip angle 90 °) in accordance with the adhesive strength evaluation method of JIS Z0237: 2000. It stuck on the adherend. After the adherend to which the film has been attached is allowed to stand in a constant temperature room at 23 ° C. for 30 minutes, the tensile tester (manufactured by A & D Co., Ltd.) is used, and the direction is 180 ° at a speed of 300 mm / min. The initial adhesive strength was measured.

(2) Evaluation of adhesive residue In a temperature-controlled room at 23 ° C. and 50% RH, the surface protective film was made into a 15 cm long by 5 cm wide acrylic plate (mirror finish, manufactured by Mitsubishi Rayon Co., Ltd.) in accordance with JIS Z0237: 2000. “Acrylite”) was attached to the entire surface. The acrylic plate on which the film was adhered was allowed to stand in a dryer at 60 ° C. for 3 days, and then cooled in a constant temperature room at 23 ° C. for 1 hour. From the cooled test piece, the film was peeled off at a high speed in the direction of 180 °, the state of contamination on the acrylic plate surface was visually confirmed, and the adhesive residue was evaluated according to the following criteria.
○: No clouding, white streaks, foreign matter, etc. on the acrylic plate surface.
X: There is any dirt such as cloudiness, white streaks, foreign matters on the surface of the acrylic plate.

(3) Evaluation of blocking resistance The obtained surface protective film was cut out in the size of A4 (length 297 mm x width 210 mm). At this time, the film was cut out so that the extrusion direction (MD direction) during film formation coincided with the A4 vertical direction. After 10 cut out films were stacked, the upper and lower sides were sandwiched between A4 size, 3 mm thick vinyl chloride plates, a weight of 5 kg was placed, stored in a dryer at 40 ° C. for 14 days, then stored at 23 ° C. And stored in a constant temperature room of 50% RH for 1 hour. Next, the film was cut out in a width of 25 mm in the MD direction, and peeled in the direction of 180 ° at a speed of 300 mm / min using a tensile tester (manufactured by A & D Co., Ltd.) to measure the blocking force. From the obtained blocking force, blocking resistance was evaluated according to the following criteria.
○: Blocking force is less than 0.8 N / 25 mm ×: Blocking force is 0.8 N / 25 mm or more

Tables 1 to 4 show the layer structures of the surface protective films produced above and the evaluation results obtained using these surface protective films.

From the results of Examples 1 to 12, it can be seen that the surface protective film of the present invention has an appropriate adhesive force to the adherend having an uneven surface shape, and has a practically weak adhesive force as a surface protective film. It was. Moreover, when peeling a film from an acrylic board, it turned out that there is no glue residue which can be visually confirmed on the adherend surface, and contamination | pollution | contamination, such as a foreign material, is not recognized. Furthermore, it turned out that it is a surface protection film which can be handled favorably without blocking.

Comparative Example 1 is an example of a surface protective film in which the surface layer and the base material layer are the same as Example 1, but a mixture of HSBR and LLDPE of 85/15 is used for the adhesive layer and the component (B2) is not blended. It is. In the surface protective film of Comparative Example 1, it was found that the adhesive strength to the adherend having a surface uneven shape was low.

In Comparative Example 2, the surface layer and the base material layer are the same as Example 1, and the blending ratio of the component (B3) of the adhesive layer is 10 parts by mass, but the blending ratio of the component (B1-1) is 50% of the lower limit. It is an example of the surface protection film which made the compounding ratio of 40 mass parts less than a mass part and a component (B2) 50 mass parts exceeding 45 mass parts of an upper limit. In the surface protective film of this comparative example 2, it turned out that the adhesive force with respect to the adherend of a surface uneven | corrugated shape is low.

In Comparative Example 3, the surface layer and the base material layer are the same as Example 1, but 90 parts by mass of the component (B) exceeding the upper limit of 85 parts by mass of the component (B1-1) of the adhesive layer. It is an example of the surface protection film which made the compounding ratio 3 mass parts less than 5 mass parts of a minimum. In the surface protective film of Comparative Example 3, it was found that the adhesion to the adherend having an uneven surface was low, the blocking power was large, and the blocking resistance was poor.

In Comparative Example 4, the surface layer and the base material layer are the same as those in Example 1, but the surface protective film is a mixture of SEPS and LLDPE of 85/15 in the adhesive layer and does not contain component (B2). It is an example. In the surface protective film of Comparative Example 1, it was found that the adhesive strength to the adherend having a surface uneven shape was low.

Comparative Example 5 uses a mixture of HDPE / LDPE = 50/50 for the base layer, uses a mixture of HSBR and LLDPE of 85/15 for the adhesive layer, and does not contain component (B2). It is an example. In the surface protective film of Comparative Example 1, it was found that the adhesive strength to the adherend having a surface uneven shape was low.

The surface protective film of the present invention is useful as a film for protecting the surface of various resin plates, glass plates, metal plates and the like. In particular, it is suitable for prisms having unevenness in the surface shape of the adherend and protective film for diffusion plates.

Claims

A surface protective film having a base material layer (A) and an adhesive layer (B), wherein the adhesive layer (B)
A copolymer (B1-1) having a styrene polymer block and a styrene random copolymer block obtained by hydrogenating the double bond portion of a random copolymer of styrene and a conjugated diene compound;
Or ab (wherein a is a styrenic polymer block, and b is a conjugated diene polymer block or an olefin weight obtained by hydrogenating a double bond in a conjugated diene polymer) Styrenic block copolymer (B1-2) represented by a combined block)
Or a block copolymer (B1-3) comprising a crystalline olefin polymer block obtained by hydrogenating a conjugated diene polymer block and a conjugated diene polymer block,
50 to 85% by mass,
5 to 45% by mass of the amorphous α-olefin polymer (B2),
5 to 45% by mass of the crystalline olefin polymer (B3),
A surface protective film characterized by comprising a mixture of the main components.
The surface protective film according to claim 1, wherein the base material layer (A) contains an olefin polymer (A1) as a main component.
3. The surface protective film according to claim 1, wherein the block copolymer (B1-3) is a block copolymer having a structure of crystalline olefin block-ethylene / butylene copolymer block-crystalline olefin block.
The surface protection according to any one of claims 1 to 3, wherein a surface layer (C) comprising an olefin polymer as a main component is provided on the base material layer (A) opposite to the adhesive layer (B). the film.
The surface according to claim 4, wherein the olefin polymer as a main component of the surface layer (C) is mainly composed of an ethylene polymer or a mixed resin of a propylene polymer and a propylene-ethylene block copolymer. Protective film.