JP5183458B2 - Surface protection film - Google Patents

Description

  The present invention relates to a surface protective film, and more specifically, to protect a surface of a building member such as a synthetic resin plate, a decorative plate, a metal plate, and a glass plate, and to protect a surface of a constituent member of a liquid crystal display such as a polarizing plate and a retardation plate. The present invention relates to a film for protecting a surface which is preferably used as an application.

  Surface protection films are affixed to building materials such as synthetic resin plates and liquid crystal display parts of optical equipment members from the viewpoint of preventing scratches and dirt on the surface during processing, transportation and transportation, and after processing or transportation and transportation. It is common to peel off and use the surface protection film which concerns later.

  Conventionally, as the surface protective film, there is a surface protective film mainly composed of an ethylene-based resin. For example, a surface protective film made of an ethylene-based resin that is polymerized from a metallocene catalyst, has a narrow composition distribution and molecular weight distribution, and does not have fish eye is described (for example, see Patent Document 1). Further, a polyethylene composed of 50 to 90% by weight of a specific low density polyethylene and 10 to 50% by weight of a specific high density polyethylene having a weight average molecular weight / number average molecular weight ratio of 9 to 15, and an ethylene-unsaturated ester A laminated film obtained by coextruding a pressure-sensitive adhesive layer made of a copolymer is described (for example, see Patent Document 2).

However, in the surface protective film described in the above patent document, since polyethylene is the main component, retention occurs inside the molding machine extruder during film formation, gelation occurs due to deterioration of the ethylene component, Since the fish eye is generated, when the product is attached to the object to be protected and stacked and stored as it is, the object to be protected is dented due to the presence of the fish eye. Therefore, for example, even if an attempt is made to use the laminated film as a polarizing plate or a retardation plate used as a liquid crystal display material, there is a problem that the image is distorted due to the dents and cannot be applied.
In addition, in view of problems of heat resistance, scratch resistance, and rigidity of polyethylene, and having improved the point defects of the metal thin film layer due to the influence of chlorine ions, it is made of polypropylene having a chlorine content of 5 ppm by weight or less. A surface protective film containing a characteristic propylene-based resin as a main component has also been proposed (see, for example, Patent Document 3). However, even in the propylene-based resin described in the patent document, gelation like polyethylene does not occur, but the molecular weight distribution is wide, that is, low molecular weight having a low molecular weight and high molecular weight having a high molecular weight are mixed. Therefore, when the high molecular weight component is formed into a film, an unmelted fine lump becomes a fish eye and exists in the film, resulting in a dent in the protected object.

  Further, both ethylene-based resins and propylene-based resins have a crystallinity distribution, but there is a problem that if the crystallinity distribution is wide and there are many low crystal components, the object to be protected is contaminated. In addition, in the process of producing the polymer, sticking of the low crystal component causes polymer adhesion in a polymerization tank or the like, resulting in deterioration of the polymer due to stagnation, and as a result, fish eyes derived from polymer degradation products exist in the film. As a result, the object to be protected is dented, and there is a problem that it cannot be applied as a surface protective film. In addition, if the crystallinity distribution is wide, the compatibility between the low crystallinity component and the high crystallinity component becomes non-uniform, and the high crystallinity component tends to exist as fish eyes in the form of a fine unmelted mass. Similarly, there is a problem that it cannot be applied as a surface protective film.

Also, a surface protective sheet in which a base material layer containing a polyolefin-based resin and an adhesive layer are formed by coextrusion for the purpose of protecting a building member having a rough surface roughness, and the adhesive layer is specified. A surface protective sheet comprising a propylene-based copolymer and a specific styrene-based thermoplastic elastomer has been proposed (see, for example, Patent Document 4). However, since the transparency is poor, it is difficult to confirm when the adherend is damaged after being attached to the adherend.
JP-A-9-111208 JP 54-133578 A JP 2006-282761 A JP 2004-2624 A

  In view of the above-mentioned problems of the prior art, the present invention has very few fish eyes, and preferably has improved peel force control and feeding performance, and construction of synthetic resin plates, decorative plates, metal plates, glass plates, etc. An object of the present invention is to provide a film for protecting a surface made of a propylene-based resin, which is excellent as a film for protecting the surface of a member, and excellent in surface protection for a constituent member of a liquid crystal display such as a polarizing plate or a retardation plate. To do.

  As a result of repeating various studies in order to solve the above problems, the present inventors have obtained a specific melt flow rate, a melting peak temperature by a differential thermal scanning calorimeter, a weight average molecular weight and a number average determined by gel permeation chromatography. By using a polypropylene-based resin having a soluble amount of 40 ° C. or less as measured by a temperature rising elution fractionation method with respect to the molecular weight, a surface protective film with less fish eyes can be obtained, and a specific ethylene as a pressure-sensitive adhesive layer.・ By combining α-olefin copolymer and a specific thermoplastic styrene-diolefin copolymer hydrogenated product, the peel force control and feeding performance are improved, and the film for surface protection has excellent transparency. And the present invention was completed.

That is, according to the first invention of the present invention, in the surface protective film in which the pressure-sensitive adhesive layer is formed on one surface of the base material layer made of propylene-based resin,
The propylene-based resin is a propylene homopolymer polymerized using a metallocene catalyst and has the following properties (A1) to (A4), or a propylene / α-olefin random copolymer,
The pressure-sensitive adhesive layer is polymerized using a metallocene catalyst, and an ethylene / alpha-olefin copolymer (component (B)) having the following properties (B1) to (B2): From an ethylene / α-olefin copolymer composition containing 5 to 95% by weight of a hydrogenated thermoplastic styrene-diolefin copolymer (component (C)) satisfying the condition (a) A film for protecting a surface.
(A1) Melt flow rate (MFR: 230 ° C., 21.18 N load) is 1 to 50 g / 10 minutes (A2) Melting peak temperature (Tmp) by differential thermal scanning calorimeter (DSC) is 120 to 170 ° C.
(A3) The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 1.5 to 3.5.
(A4) Atsushi Nobori elution fractionation (TREF) 40 ° C. The following solubles measured by method _{(S 40)} is 10 wt% or less (B1) Density [d] is 0.86 5 ~0.9 05 g / cm ³
(B2) weight average molecular weight (Mw) and the ratio of the number average molecular weight (Mn) (Mw / Mn) is 3.5 or less (C1) styrene content [St] 10 to 5 0 wt%
Condition (a): The density [d] (g / cm ³ ) of the component (B) and the styrene content [St] (wt%) of the component (C) satisfy the following formula (1) ″ .
640 [d] -555.2 <[St] <640 [d] -541.2 (1) "

According to a second aspect of the present invention, there is provided a surface protecting film according to the first aspect, wherein the propylene-based resin further has the following property (A5).
(A5) The range (T ₁₀₀ -T ₂₀ ) of the temperature (T ₁₀₀ ) at the end of elution by 100 wt% from the temperature (T ₂₀ ) at the elution of 20 wt% by the temperature rising elution fractionation (TREF) method is 30 ° C. Less than

  According to the third invention of the present invention, in the first or second invention, the adhesive layer is formed on one surface of the base material layer, and the release treatment layer is formed on the other surface. A surface protective film is provided.

  Further, according to the fourth invention of the present invention, in any one of the first to third inventions, it is used for surface protection of building members such as a synthetic resin plate, a decorative plate, a metal plate, and a glass plate. A surface protective film is provided.

  According to a fifth aspect of the present invention, in any one of the first to third aspects, the surface is used for protecting a surface of a liquid crystal display component such as a polarizing plate or a retardation plate. A protective film is provided.

  The film for surface protection of the present invention is made of a specific propylene resin, because the crystallinity distribution of the resin is narrow, the amount of low crystalline components eluted is small, the molecular weight distribution is narrow, and the high molecular weight component is small. There is very little unmelted fish eye during film forming. For this reason, even if a surface protection film is affixed on a to-be-protected object and stored in a stacked manner, the to-be-protected object does not dent. Moreover, the film for surface protection of this invention is excellent in blocking property without using an antiblocking agent, and is excellent in transparency. Furthermore, as a pressure-sensitive adhesive layer, by using a specific ethylene / α-olefin copolymer polymerized using a metallocene catalyst and a specific hydrogenated styrene-diolefin copolymer, a base material layer and a pressure-sensitive adhesive layer A film for surface protection having a characteristic that when at least one of the layers is laminated in a molten state, it adheres firmly, and when the roll is unwound, the adhesive layer and the base material layer both come into contact with each other in a solid state. can do.

  The present invention is a surface protective film having a pressure-sensitive adhesive layer formed on one surface of a base material layer and a base material layer, and further, if necessary, a pressure-sensitive adhesive layer and a release treatment layer on the other surface, The base material layer is polymerized using a metallocene catalyst, and a propylene homopolymer or propylene / α-olefin random copolymer having characteristics (A1) to (A4) and, if necessary, further characteristics (A5) It is composed of a propylene-based resin that is a coalescence, and the pressure-sensitive adhesive layer is polymerized by using a metallocene catalyst, and has characteristics (B1) to (B2) and, if necessary, further characteristics (B3) to (B4). α-olefin copolymer (component (B)) 5 to 95% by weight and thermoplastic styrene-diolefin copolymer hydrogenated product (component (C)) 5 to 95% by weight having characteristics (C1) And condition (a) It is the film for surface protection which consists of an ethylene-alpha-olefin copolymer composition to satisfy | fill. Hereinafter, the component of each layer of the film for surface protection of this invention and the manufacturing method of the film for surface protection are demonstrated in detail.

1. Base material layer The base material layer in the film for surface protection of the present invention is composed of a propylene-based resin. As the propylene-based resin, a propylene homopolymer or a propylene / α-olefin random copolymer of a copolymer of propylene and an α-olefin can be used. Here, examples of the α-olefin as the copolymer component include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and the like.

  Specific examples of the propylene / α-olefin random copolymer used in the present invention include propylene / ethylene random copolymer, propylene / 1-butene random copolymer, propylene / 1-hexene random copolymer, propylene / ethylene. -1-butene copolymer etc. are mentioned. Preferably, a propylene / ethylene random copolymer, a propylene / 1-butene random copolymer, a propylene / ethylene / 1-butene copolymer, and the like are used. More preferred is a propylene / ethylene random copolymer.

  The propylene-based resin used in the present invention has the following characteristics (A1) to (A4), and further has characteristics (A5) as necessary.

(A1) Melt flow rate The melt flow rate (MFR) of the propylene-based resin used in the present invention is 1 to 50 g / 10 minutes, preferably 2 to 30 g / 10 minutes, and more preferably 5 to 20 g / 10. Minutes, most preferably 7-15 g / 10 min.
If the MFR is less than 1 g / 10 minutes, the extrusion characteristics are deteriorated and the productivity is lowered, which is not preferable, and if the MFR exceeds 50 g / 10 minutes, the thickness accuracy at the time of film forming tends to be deteriorated. MFR can be adjusted by the amount of hydrogen during polymerization. For example, increasing the amount of hydrogen increases the MFR.
In addition, the melt flow rate (MFR: unit g / 10min) employ | adopted in this invention is a value measured by 230 degreeC and a load of 21.18N load based on JISK-7210-1995.

(A2) Melting peak temperature The melting peak temperature (Tmp) of the propylene-based resin used in the present invention is 120 to 170 ° C, preferably 120 to 165 ° C, more preferably 120 to 160 ° C, and most preferably. Is 120 ° C to 150 ° C. When the melting peak temperature is less than 120 ° C., the heat resistance is inferior, and the surface protection film is likely to be deformed during the processing step of applying heat to the surface protection film on the object to be protected. When the melting peak temperature is higher than 170 ° C., the impact strength is inferior, and there is a possibility that tearing may occur when the surface protection film is attached to an object to be protected. The melting peak temperature (Tmp) can be adjusted by the amount of α-olefin used. For example, as the amount of α-olefin increases, the melting peak temperature (Tmp) decreases.
In addition, the melting peak temperature (Tmp: unit ° C) employed in the present invention is a differential scanning calorimeter (DSC), a sample amount of 5.0 mg is taken and held at 200 ° C for 5 minutes, and then 40 ° C. This is a value for measuring the melting peak temperature (Tmp) when crystallization is performed at a temperature lowering speed of 10 ° C./min until further melting at a temperature rising speed of 10 ° C./min.

(A3) Ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) Ratio (Mw / Mn) of weight average molecular weight (Mw) and number average molecular weight (Mn) of the propylene-based resin used in the present invention is It is 1.5-3.5, Preferably it is 1.7-3.2, More preferably, it is 2.0-3.0, Most preferably, it is 2.3-2.8. When (Mw / Mn) is less than 1.5, the viscosity of the molten resin becomes high, the melt fluidity becomes poor, and extrusion molding becomes difficult. On the other hand, when (Mw / Mn) exceeds 3.5, the abundance ratio of molecules having a low molecular weight and molecules having a high molecular weight becomes high, and the high molecular weight component becomes an unmelted fish eye at the time of film formation and is stuck on a protected object. After that, if the products are stacked and stored as they are, the objects to be protected will be dented.
(Mw / Mn) can be adjusted by changing the polymerization conditions (polymerization temperature, polymerization pressure) during production and the type of catalyst used.

The weight average molecular weight (Mw) / number average molecular weight (Mn) used in the present invention is measured by gel permeation chromatography (GPC). The measurement conditions are as follows.
Apparatus: GPC 150C type manufactured by Waters Inc. Detector: 1A infrared spectrophotometer manufactured by MIRAN (measurement wavelength: 3.42 μm)
Column: Showa Denko Co., Ltd. AD806M / S 3 (column calibration is Tosoh monodisperse polystyrene (A500, A2500, F1, F2, F4, F10, F20, F40, F288 each 0.5 mg / ml solution) The logarithm of the elution volume and molecular weight was approximated by a quadratic equation, and the molecular weight of the sample was converted to polypropylene using the viscosity equation of polystyrene and polypropylene, where the coefficient of the viscosity equation of polystyrene was α = 0. .723, log K = −3.967, and polypropylene has α = 0.707 and log K = −3.616.)
Measurement temperature: 140 ° C
Concentration: 20 mg / 10 mL
Injection volume: 0.2ml
Solvent: Orthodichlorobenzene Flow rate: 1.0 ml / min Viscosity formula: log [η] = log K + α × log M

(A4) Soluble content of 40 ° C. or less by temperature rising elution fractionation (TREF) method (S ₄₀ )
The soluble content (S ₄₀ ) of 40 ° C. or less measured by the temperature rising elution fractionation (TREF) method of the propylene resin used in the present invention is 10% by weight or less, preferably 8% by weight or less, more preferably Is 6% by weight or less, and most preferably 4% by weight or less.
When the soluble content (S ₄₀ ) of 40 ° C. or less measured by the temperature rising elution fractionation (TREF) method is more than 10% by weight, there is a problem that the protected material is contaminated by the low crystalline component sticky component. In addition, in the process of producing the polymer, sticking of the low crystal component causes polymer adhesion in a polymerization tank or the like, resulting in deterioration of the polymer due to stagnation, and as a result, fish eyes derived from polymer degradation products exist in the film. End up.
The soluble content (S ₄₀ ) of 40 ° C. or lower can be adjusted by changing the polymerization conditions (polymerization temperature, polymerization pressure) during production, the type and amount of the catalyst and α-olefin used, and the composition.

(A5) by Atsushi Nobori elution fractionation _(T 100 _{-T 20)}
Width (T ₁₀₀ -T) of temperature (T ₁₀₀ ) when 100 wt% elution is completed from temperature (T ₂₀ ) when 20 wt% is eluted by the temperature rising elution fractionation (TREF) method of the propylene resin used in the present invention. ₂₀ ) is preferably 30 ° C. or lower, more preferably 25 ° C. or lower, further preferably 20 ° C. or lower, and most preferably 15 ° C. or lower. When (T ₁₀₀ -T ₂₀ ) exceeds 30 ° C., a component having high crystallinity and a component having low crystallinity are simultaneously present in the propylene-based resin, and the size and quality of the crystal component are not uniform. Therefore, there is a possibility that the melted resin viscosity has unevenness and unmelted fine lump becomes fish eye and exists in the film.
Using a Atsushi Nobori elution fractionation (T _{100 -T 20),} the polymerization conditions at the time of production (polymerization temperature, polymerization pressure), the type of catalyst and α- olefin used and the amount can be adjusted by changing the composition.

The temperature rising elution fractionation (TREF) method employed in the present invention is the method shown below.
That is, a sample is dissolved in orthodichlorobenzene at 140 ° C. to obtain a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to 40 ° C. at a rate of 4 ° C./min, and held for 10 minutes. Thereafter, orthodichlorobenzene as a solvent is caused to flow through the column at a flow rate of 1 mL / min, and components dissolved in 40 ° C orthodichlorobenzene are eluted in the TREF column for 10 minutes, and then the heating rate is 100 ° C / hour. The column is linearly heated to 140 ° C. to obtain an elution curve.
From the elution curve obtained according to the above conditions, the ratio (% by weight) to the total amount of components eluted at 40 ° C. is calculated. Moreover, to calculate the width of the temperature at which eluted 20% by weight temperature upon 100 wt% elution-ending from _{(T 20) (T 100)} (T 100 -T 20). Conditions such as a column to be used, a solvent, and a temperature are as follows.
Column size: 4.3mmφ × 150mm
Column packing material: 100 μm surface inert treatment glass beads Solvent: Orthodichlorobenzene Sample concentration: 5 mg / mL
Sample injection volume: 0.2 mL
Solvent flow rate: 1 mL / min Detector: Fixed wavelength infrared detector MIOX 1A manufactured by FOXBORO
Measurement wavelength: 3.42 μm

Such a propylene resin is a propylene homopolymer polymerized by a metallocene catalyst or a propylene / α-olefin random copolymer that is polymerized using a metallocene catalyst. Since the distribution and molecular weight distribution are narrow, as described above, there are few components that become fish eye.
On the other hand, when a propylene homopolymer polymerized with a catalyst other than a metallocene catalyst such as a so-called Ziegler-Natta catalyst containing magnesium, titanium, halogen, and an electron donor as an essential component, or a propylene / α-olefin random copolymer is used, Wide molecular weight distribution and high content of high molecular weight component, wide crystal distribution, many low crystal components, and non-uniform crystallinity distribution, resulting in unmelted fine lump in the film And it becomes easy to exist as fish eyes.

  The metallocene catalyst used in the present invention is (i) a group 4 transition metal compound containing a ligand having a cyclopentadienyl skeleton (so-called metallocene compound) and (ii) a metallocene compound. It is a catalyst comprising a cocatalyst that can be activated to a stable ionic state and, if necessary, (iii) an organoaluminum compound, and any known catalyst can be used. The metallocene compound is preferably a bridged metallocene compound capable of stereoregular polymerization of propylene, and more preferably a bridged metallocene compound capable of isoregular polymerization of propylene. Each component will be described.

  Examples of (i) metallocene compounds include JP-A-60-35007, JP-A-63-130314, JP-A-63-295607, JP-A-1-275609, JP-A-2-41303, and JP-A-2-41303. JP-A-2-131488, JP-A-2-76887, JP-A-3-163888, JP-A-4-30087, JP-A-4-21694, JP-A-5-43616, JP-A-5-209913, JP-A-6 No. 239914, JP-A-7-504934, and JP-A-8-85708.

More specifically, methylene bis (2-methylindenyl) zirconium dichloride, ethylenebis (2-methylindenyl) zirconium dichloride, ethylene 1,2- (4-phenylindenyl) (2-methyl-4-phenyl) -4H-azulenyl) zirconium dichloride, isopropylidene (cyclopentadienyl) (fluorenyl) zirconium dichloride, isopropylidene (4-methylcyclopentadienyl) (3-t-butylindenyl) zirconium dichloride, dimethylsilylene (2- Methyl-4-t-butyl-cyclopentadienyl) (3′-t-butyl-5′-methyl-cyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, dimethylsilylenebis (4,5 , , 7-tetrahydroindenyl) zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4-phenylindenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-phenylindenyl)] zirconium Dichloride, dimethylsilylenebis [4- (1-phenyl-3-methylindenyl)] zirconium dichloride, dimethylsilylene (fluorenyl) t-butylamidozirconium dichloride, methylphenylsilylenebis [1- (2-methyl-4, ( 1-naphthyl) -indenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4,5-benzoindenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-methyl-4-phenyl-4H) -Azulenyl) ] Zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] Zirconium dichloride, diphenylsilylene bis [1- (2-methyl-4- (4-chlorophenyl) -4H-azulenyl)] zirconium dichloride, dimethylsilylene bis [1- (2-ethyl-4- (3-fluorobiphenylyl) ) -4H-azurenyl)] zirconium dichloride, dimethylgermylenebis [1- (2-ethyl-4- (4-chlorophenyl) -4H-azurenyl)] zirconium dichloride, dimethylgermylenebis [1- (2-ethyl-) 4-phenylindenyl)] zirconium Zirconium compounds such as chloride can be exemplified. In the above, compounds in which zirconium is replaced with titanium or hafnium can be used in the same manner. In some cases, a mixture of a zirconium compound and a hafnium compound can be used. Further, the chloride can be replaced with other halogen compounds, hydrocarbon groups such as methyl, isobutyl and benzyl, amide groups such as dimethylamide and diethylamide, alkoxide groups such as methoxy group and phenoxy group, hydride groups and the like.
Among these, a metallocene compound in which an indenyl group or an azulenyl group is crosslinked with silicon or a germyl group is preferable. In particular, a polymer obtained by a catalyst in which a metallocene compound having an azulenyl group and a clay mineral are combined has excellent balance of film forming property and low fish eye.

The metallocene compound may be used by being supported on an inorganic or organic compound carrier.
The carrier is preferably an inorganic or organic porous compound. Specifically, ion-exchange layered silicate, zeolite, SiO ₂ , Al ₂ O ₃ , silica alumina, MgO, ZrO ₂ , TiO ₂ , B Examples include inorganic compounds such as ₂ O ₃ , CaO, ZnO, BaO, and ThO ₂ , organic compounds composed of porous polyolefin, styrene / divinylbenzene copolymer, olefin / acrylic acid copolymer, and the like, or a mixture thereof. It is done.

  (Ii) As a co-catalyst that can be activated to a stable ionic state by reacting with a metallocene compound, an organoaluminum oxy compound (for example, an aluminoxane compound), an ion-exchange layered silicate, a Lewis acid, a boron-containing compound, an ionic compound And fluorine-containing organic compounds.

  (Iii) Examples of the organoaluminum compound include trialkylaluminum such as triethylaluminum, triisopropylaluminum, and triisobutylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, alkylaluminum dihalide, alkylaluminum hydride, and organoaluminum alkoxide. Can be mentioned.

Examples of the polymerization method include a slurry method using an inert solvent in the presence of the catalyst, a solution method, a gas phase method substantially using no solvent, or a bulk polymerization method using a polymerization monomer as a solvent. . As a method for obtaining propylene used in the present invention, for example, a desired polymer can be obtained by adjusting the polymerization temperature and the comonomer amount and appropriately controlling the molecular weight and crystallinity distribution.
Such polypropylene can be appropriately selected from those commercially available as metallocene polypropylene. Examples of commercially available products include “Wintech” manufactured by Nippon Polypro.
The propylene resin of the present invention may be composed of one type or a combination of two or more types as long as the above properties are satisfied.

2. Pressure-sensitive adhesive layer In the surface protective film of the present invention, a pressure-sensitive adhesive layer is formed on one surface of the base material layer made of the propylene-based resin. The pressure-sensitive adhesive layer includes an ethylene / α-olefin copolymer containing the following ethylene / α-olefin copolymer (component (B)) and the following thermoplastic styrene / diolefin copolymer hydrogenated product (component (C)). It consists of a copolymer composition.

(1) Ethylene / α-olefin copolymer (component (B))
The ethylene / α-olefin copolymer used in the pressure-sensitive adhesive layer of the present invention is polymerized using a metallocene catalyst, and has the following characteristics (B1) to (B2) and, if necessary, (B3) to (B4). Has characteristics. By using this ethylene / α-olefin copolymer for the pressure-sensitive adhesive layer, when at least one of the base material layer and the pressure-sensitive adhesive layer is laminated in a molten state, both the pressure-sensitive adhesive layer and the base material layer are firmly bonded. Can be made into a surface protective film having the property that it can be peeled off smoothly when the roll is unwound from the rolled state in which it is in a solid state, and the peel strength from the base material layer is improved in the surface protective film manufacturing process, and the surface When the protective film is used, the feeding property is improved.

In the ethylene / α-olefin copolymer, the α-olefin copolymerized with ethylene is preferably an α-olefin having 3 to 20 carbon atoms, such as propylene, butene-1, hexene-1, octene-1, and the like. In particular, propylene, butene-1, or hexene-1 is preferable. Further, the α-olefin copolymerized with ethylene may be one type or two or more types.
The ethylene content in the ethylene / α-olefin copolymer is preferably 50% by weight or more. If the ethylene content is low, the adhesive strength tends to be weak, so the effect as the pressure-sensitive adhesive layer may be inferior. The content of α-olefin is appropriately adjusted according to the required density.

(B1) Density [d]
The density [d] of the ethylene / α-olefin copolymer is 0.860 to 0.918 g / cm ³ , preferably 0.865 to 0.905 g / cm ³ , and more preferably 0.870 to 0.898 g / cm ³ . cm ³ . When the density is less than 0.860 g / cm ³ , the adhesive strength becomes too high, and there is a problem that the material is peeled off from the base material layer and a mark remains on the protected object. In addition, when the density exceeds 0.918 / cm ³ , the adhesive strength becomes too weak and the effect as an adhesive layer cannot be obtained.
In addition, a density is a value measured based on JIS-K6922-2: 1997 appendix (23 degreeC).

(B2) Ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)
The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the ethylene / α-olefin copolymer is 3.5 or less, preferably 1.5 to 3.0, more Preferably it is 2.0-2.5. If it is the said range, there will be no stickiness and it is preferable.
Here, Mw / Mn is defined by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). The measuring method of Mw / Mn is as follows.
Apparatus: Waters GPC 150C type Detector: MIRAN 1A infrared spectrophotometer (measurement wavelength, 3.42 μm)
Column: 3 AD806M / S manufactured by Showa Denko Co., Ltd. (column calibration is Tosoh monodisperse polystyrene (0.5 mg / ml solution of each of A500, A2500, F1, F2, F4, F10, F20, F40, and F288) The logarithm of the elution volume and molecular weight was approximated by a quadratic equation. The molecular weight of the sample was converted to polyethylene using the viscosity formula of polystyrene and polyethylene. Here, the coefficients of the viscosity formula of polystyrene are α = 0.723 and log K = −3.767, and polyethylene has α = 0.723 and log K = −3.407.
Measurement temperature: 140 ° C
Injection volume: 0.2ml
Concentration: 20 mg / 10 mL
Solvent: Orthodichlorobenzene Flow rate: 1.0 ml / min

(B3) Melt flow rate The melt flow rate (MFR: 190 ° C, 21.18N load) of the ethylene / α-olefin copolymer is preferably 0.1 to 50 g / 10 min, more preferably 1 to 30 g / 10. Minute, particularly preferably 2 to 15 g / 10 minutes. When the MFR is less than 0.1 g / 10 min, the extrusion characteristics are likely to deteriorate, and there is a problem in that the interface with the base film made of the propylene resin of the present invention is roughened. If it exceeds 50 g / 10 min, it causes thickness unevenness.
In addition, MFR is a value measured based on JIS-K6922-2: 1997 appendix (190 degreeC, 21.18N load).

(B4) In (TREF) measurement, the amount of elution at 20 ° C. or lower The amount of elution at 20 ° C. or lower in the temperature rising elution fractionation (TREF) measurement using orthodichlorobenzene of ethylene / α-olefin copolymer as a solvent is preferably It is 60% by weight or less, more preferably 50% by weight or less, and particularly preferably 15% by weight or less.
In addition, the elution amount of 65 ° C. or more by temperature rising elution fractionation (TREF) of the ethylene / α-olefin copolymer is 0.3 wt% or more, preferably 1.0 wt% or more, more preferably 2.0 wt%. % Or more, and more preferably 5.0% by weight or more. If it is the said range, since favorable adhesive strength can be maintained, it is preferable.

Here, the amount of elution by TREF is measured by the following cross-fractionation chromatograph (CFC) comprising a temperature rising elution fractionation (TREF) portion for performing crystalline fractionation and a gel permeation chromatography (GPC) portion for performing molecular weight fractionation. Depending on the method.
First, a polymer sample was completely dissolved in orthodichlorobenzene (ODCB) containing 0.5 mg / mL BHT at 140 ° C., and this solution was passed through a sample loop of the apparatus, and a TREF column (inert) maintained at 140 ° C. The polymer sample is crystallized by slowly cooling to a predetermined first elution temperature. After maintaining at a predetermined temperature for 30 minutes, ODCB is passed through a TREF column, whereby the eluted component is injected into the GPC section to perform molecular weight fractionation, and an infrared detector (MIRAN 1A IR detector manufactured by FOXBORO, A chromatogram is obtained with a measuring wavelength of 3.42 μm). Meanwhile, in the TREF part, the temperature is raised to the next elution temperature, and after obtaining the chromatogram of the first elution temperature, the elution component at the second elution temperature is injected into the GPC part. Thereafter, the same operation is repeated to obtain a chromatogram of the eluted components at each elution temperature. The measurement conditions are shown below.
Equipment: CFC-T102L manufactured by Dia Instruments
GPC column: Showa Denko AD-806MS (3 connected in series)
Solvent: ODCB
Sample concentration: 3 mg / mL
Injection volume: 0.4mL
Crystallization rate: 1 ° C / min Solvent flow rate: 1 mL / min GPC measurement time: 34 minutes Stabilization time after GPC measurement: 5 minutes Elution temperature: 0, 5, 10, 15, 20, 25, 30, 35, 40, 45 49, 52, 55, 58, 61, 64, 67, 70, 73, 76, 79, 82, 85, 88, 91, 94, 97, 100, 102, 120, 140
Data analysis: The chromatograms of the elution components obtained at each elution temperature obtained by measurement are processed by the data processing program attached to the instrument, and the elution amount is standardized so that the total is 100% (proportional to the area of the chromatogram) ) Is required. In addition, an integrated elution curve for the elution temperature is calculated. An elution amount of 20 ° C. or lower and an elution amount of 65 ° C. or higher are determined from the obtained elution curve.

  The ethylene / α-olefin copolymer is produced by using a metallocene catalyst in a process such as a gas phase method, a solution method, a high pressure method, a slurry method, etc., with ethylene and propylene, 1-butene, 1-hexene, 4-methyl-1 -Can be produced by copolymerization with α-olefins such as pentene and 1-octene, and those produced by a high pressure method or a solution method using a metallocene catalyst are particularly narrow in molecular weight distribution and crystallinity distribution. preferable.

In the production of an ethylene / α-olefin copolymer, the elution amount of density, Mw / Mn, MFR, TREF 20 ° C. or less depends on the polymerization temperature, the polymerization pressure, the catalyst used, and the type and composition of ethylene and α-olefin. By changing, it can be adjusted easily.
For example, the density tends to increase as the polymerization temperature is increased, reducing the α-olefin feed rate. In addition, the amount of elution below TREF of 20 ° C. tends to increase as the α-olefin supply amount is increased or the polymerization temperature is lowered. Furthermore, the MFR tends to decrease with increasing polymerization pressure.

  Specific examples of ethylene / α-olefin copolymers using metallocene catalysts include Harmolex series, Kernel series, Evolue series made by Prime Polymer Co., Ltd., Sumitomo Chemical Co., Ltd. Exelen GMH series and excelen FX series.

(2) Thermoplastic styrene-diolefin copolymer hydrogenated product (component (C))
The hydrogenated thermoplastic styrene-diolefin copolymer used in the pressure-sensitive adhesive layer of the present invention has the following property (C1).

(C1) Styrene content [St]
The styrene content [St] of the hydrogenated thermoplastic styrene-diolefin copolymer is 5 to 60% by weight, preferably 10 to 50% by weight, and more preferably 20 to 40% by weight. When the styrene content is less than 5% by weight, the effect of improving the transparency is not noticeable, which is not preferable. On the other hand, if it exceeds 60% by weight, the affinity with the propylene-based resin is remarkably lowered, so that the dispersibility is lowered and the flexibility is remarkably lowered.
The styrene content is measured by infrared analysis based on the absorption based on the out-of-plane bending vibration of the C—H bond with respect to the plane of the benzene nucleus of 699 to 720 cm ⁻¹ .

  The hydrogenated thermoplastic styrene-diolefin copolymer is obtained by hydrogenating a thermoplastic styrene-diolefin copolymer. The hydrogenated thermoplastic styrene-diolefin copolymer may be a block copolymer or a random copolymer. A block copolymer is preferred.

  In the thermoplastic styrene-diolefin block copolymer hydrogenated product, when the styrene block is represented by STY and the diolefin block hydrogenated product is represented by DEN, STY-DEN, STY-DEN-STY, DEN-STY-DEN- A copolymer having a structure such as STY or STY-DEN-STY-DEN-STY can be given.

  Examples of the monomer constituting the diolefin hydrogenated block include hydrogenated butadiene, isoprene, vinylated polyisoprene, etc., and these may be used alone or in admixture of two or more. it can.

  Specific examples of hydrogenated products of block copolymers of styrene blocks and diolefin blocks include, for example, hydrogenated products of styrene-butadiene block copolymers, hydrogenated products of styrene-isoprene block copolymers, styrene- Examples thereof include hydrogenated products of vinylated polyisoprene block copolymers. These can be used alone or in admixture of two or more.

  The hydrogenated styrene-butadiene block copolymer is sold as “Clayton G” by Clayton Polymer Japan Co., Ltd., and as “Tough Tech” by Asahi Kasei Kogyo Co., Ltd. The hydrogenated styrene-isoprene block copolymer is sold by Kuraray Co., Ltd. under the trade name “Septon”. A hydrogenated product of a styrene-vinylated polyisoprene block copolymer is sold by Kuraray Co., Ltd. under the trade name “Hibler”. You may select and use suitably from these goods groups.

  In the hydrogenated thermoplastic styrene-diolefin random copolymer, examples of the monomer constituting the diolefin hydrogenated block include butadiene, isoprene, vinylated polyisoprene, and the like. , Or a mixture of two or more.

  Specific examples of the hydrogenated random copolymer of styrene and diolefin include hydrogenated styrene butadiene random copolymer, hydrogenated styrene-isoprene random copolymer, and styrene-vinylated polyisoprene random. Examples include hydrogenated products of copolymerization, and these can be used alone or in admixture of two or more.

  A hydrogenated product of a styrene-butadiene random copolymer is sold under the trade name “Dynalon” by JSR Corporation.

  Furthermore, a hydrogenated product of a thermoplastic styrene-diolefin block copolymer and a hydrogenated product of a thermoplastic styrene-diolefin random copolymer can be mixed and used.

(3) Relationship between ethylene / α-olefin copolymer and thermoplastic styrene / diolefin copolymer hydrogenated product The ethylene / α-olefin copolymer composition used in the pressure-sensitive adhesive layer of the present invention is the above ethylene / α-olefin copolymer composition. Although it is a composition containing an α-olefin copolymer and a thermoplastic styrene-diolefin copolymer hydrogenated product, it is necessary to satisfy the following condition (a).
Condition (a): Density [d] (g / cm ³ ) of ethylene / α-olefin copolymer and styrene content [St] (wt%) of hydrogenated thermoplastic styrene-diolefin copolymer are represented by the following formula: Satisfy the relationship of (1)
640 [d] -561.2 <[St] <640 [d] -539.2 (1)
Preferably, the formula (1) ′ is satisfied,
640 [d] −558.2 <[St] <640 [d] −539.2 (1) ′
More preferably, the expression (1) ″ is satisfied.
640 [d] -555.2 <[St] <640 [d] -541.2 (1) "

When the styrene content [St] (% by weight) is out of the relationship of the formula (1), a sufficient effect of improving transparency is not seen.
The formula (1) has been derived empirically, and the theoretical meaning has not been clarified, but the ethylene / α-olefin copolymer and the thermoplastic styrene in the range of the formula (1) are used. In combination with the diolefin copolymer hydrogenated product, the affinity of both components is increased, the dispersibility of the composition is increased, and the refractive index of each component approaches and the scattering decreases. .

(4) Blending ratio of ethylene / α-olefin copolymer and thermoplastic styrene / diolefin copolymer hydrogenated product Ethylene / α-olefin copolymer and thermoplastic styrene / diolefin used in the pressure-sensitive adhesive layer of the present invention The blending ratio of the copolymer is set such that the hydrogenated thermoplastic styrene-diolefin copolymer is 5 to 95% by weight with respect to 5 to 95% by weight of the ethylene / α-olefin copolymer. Preferably, the hydrogenated thermoplastic styrene-diolefin copolymer is 10 to 80% by weight relative to 20 to 90% by weight of the ethylene / α-olefin copolymer. More preferably, the hydrogenated thermoplastic styrene-diolefin copolymer is 15 to 60% by weight with respect to 40 to 85% by weight of the ethylene / α-olefin copolymer. If the ethylene / α-olefin copolymer exceeds 95% by weight, the adhesive strength becomes too weak and the effect as an adhesive layer cannot be obtained. When the thermoplastic styrene-diolefin copolymer hydrogenated product exceeds 95% by weight, there is a problem that the adhesive strength becomes too high, and the film is peeled off from the surface protective film and a peeled mark remains on the object to be protected.

  These pressure-sensitive adhesives can be used singly or in combination of two or more, as long as the effects of this object are not impaired.

3. Release treatment layer In the surface protective film of the present invention, a release treatment layer may be formed on the other surface of the pressure-sensitive adhesive layer formed on one of the base material layers made of the propylene-based resin. Examples of the release treatment layer include a layer formed with a release treatment agent such as a silicone-based or long-chain alkyl release treatment agent, a layer formed by roughening the surface of the film, and the like.
By using a layer formed of a silicone-based or long-chain alkyl-based release treatment agent, the roll peels off when the roll is unwound from the roll-wound state where both the adhesive layer and the release treatment layer are in contact with each other in a solid state. It can be set as the film for surface protection which has the characteristic that this improves. Moreover, since it is possible to improve the feedability without roughening the surface of the release treatment layer, it is possible to obtain a surface protective film while maintaining excellent transparency.

  As the silicone release treatment agent, a commonly used silicone release treatment agent mainly composed of dimethylpolysiloxane can also be used. It is also possible to use a silicone release treatment agent containing a three-dimensional organopolysiloxane. Specifically, a silicone-based release treatment agent containing organopolysiloxane as a main component and blended with a cellulose derivative such as methyl cellulose, ethyl cellulose, acetyl cellulose, alkyd resin, or the like is preferably used. By incorporating a cellulose derivative, an alkyd resin, or the like, it is possible to control the release property of the silicone release agent. The cellulose derivative and alkyd resin are preferably blended in an amount of 5 to 50% by weight in the silicone-based release treatment agent.

Depending on the type of curing reaction (crosslinking reaction) of the organopolysiloxane, it is roughly divided into a condensation reaction type and an addition reaction type, but in the present invention, any reaction type may be used.
For example, as the condensation reaction type silicone release agent, for example, a silicone release agent in which a cellulose derivative or an alkyd resin is blended with an organopolysiloxane having a silanol group at a molecular terminal is mentioned. Here, as the organopolysiloxane having a silanol group at the molecular end, a polysiloxane in which an alkyl group such as a methyl group or an ethyl group or a phenyl group is introduced as a side chain functional group (for example, dimethyl diphenylpolysiloxane) is used. It is preferable that the release agent has a good compatibility with the cellulose derivative and the alkyd resin, and a stable release property. In addition, the organopolysiloxane having a silanol group at the molecular end is appropriately blended with a crosslinking agent such as an alkoxy group-containing organopolysiloxane, or a catalyst such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, or zinc octylate. May be. Moreover, resin, such as an acrylic resin, can also be suitably mix | blended as a 3rd component as needed. In the silicone release agent, the crosslinking agent is preferably 4 to 20% by weight, the catalyst is preferably 5 to 10% by weight, and the resin as the third component is preferably 5 to 26% by weight.

  As an addition reaction type silicone release agent, for example, a silicone release agent in which a cellulose derivative or alkyd resin is blended with organopolysiloxane having at least two alkenyl groups such as vinyl groups bonded to silicon atoms in one molecule. Agents. Here, as the above-mentioned organopolysiloxane, it is preferable to use an organopolysiloxane having an alkyl group such as a methyl group or an ethyl group or a phenyl group introduced as a functional group of the side chain, whereby cellulose derivatives or alkyds are used. A release agent having good compatibility with the resin and stable release characteristics can be obtained. The organopolysiloxane may be appropriately blended with a crosslinking agent such as an organohydrodiene polysiloxane and a catalyst such as a platinum compound such as chloroplatinic acid.

  The silicone-based release treatment agent can be appropriately selected from commercially available products. For example, as a condensation reaction type silicone release agent, KS available from Shin-Etsu Chemical Co., Ltd., KS -723A / B (consisting of dimethyl diphenylpolysiloxane, methoxysilicone and ethylcellulose) is X-62-9201A / B available from Shin-Etsu Chemical Co., Ltd. as an addition reaction type silicone release agent. be able to.

Examples of the long-chain alkyl release agent include a polymer of a long-chain alkyl acrylate having 12 or more carbon atoms, a copolymer of a long-chain alkyl acrylate and another vinyl monomer, or a long-chain alkyl isocyanate to polyvinyl alcohol. And a release agent obtained from a reaction product obtained by reacting the long-chain alkyl component.
For example, BP type manufactured by Nitto Denko Corporation, ashioresin manufactured by Ashio Sangyo Co., Ltd., and Pyroleil manufactured by Yushi Co., Ltd. can be used.

  Examples of the release treatment layer include a method of forming a release treatment layer by applying a silicone-based or long-chain alkyl release treatment agent. In consideration of adhesion to the base material layer, a release treatment agent is applied to the propylene resin. It can mix | blend and can be used as a peeling process layer. When blending and using the above release treatment agent in a propylene resin, the total content of the propylene resin and the release treatment agent is 100% by weight, and the content of the propylene resin is 99 to 99.95% by weight, The content of the release treatment agent is 1 to 0.05% by weight.

The surface of the release treatment layer side of the film that is roughened to improve the releasability is preferably the center surface average roughness (Ra) of the release treatment layer surface in the following measurement conditions (c1) to (c6). If it is in the range of 0.2-1.5 micrometers, the resin used will not be specifically limited, A well-known thermoplastic resin or a thermosetting resin, or those mixtures may be sufficient. A layer made of a polyolefin resin is preferable. Specifically, the propylene / α-olefin block copolymer alone, or the propylene homopolymer blended with the propylene / α-olefin block copolymer, or the propylene / α-olefin random copolymer with propylene・ A blend of an α-olefin block copolymer, a low density polyethylene alone, a high density polyethylene alone, a blend of a high density polyethylene in a low density polyethylene, or a low density polyethylene in a propylene homopolymer, Or blended with high density polyethylene, or blended with propylene / α-olefin random copolymer with low density polyethylene, or blended with high density polyethylene, or propylene / α-olefin block copolymer with low density polyethylene, Or Those blended with density polyethylene, or may include those in which these things polyolefin resin blended two or more, or blended with such different thermoplastic resin compatible with these polyolefin resins. More preferably, a propylene / α-olefin block copolymer, low density polyethylene, or high density polyethylene blended with the propylene resin used in the base material layer of the present invention is from the viewpoint of fish eye and delamination. Also good.
(C1) The radius of curvature of the stylus tip is 5 μm
(C2) Cut-off wavelength is 0.80 mm
(C3) Cutoff type is 2CR (phase compensation)
(C4) Measurement speed is 0.3 mm / second (c5) Measurement direction is MD direction of film (c6) Measurement length is 2 mm

In order to roughen the film surface to form irregularities and improve the peelability, the irregularities on the film surface are preferably 0.2 to 1.5 μm in center plane average roughness (Ra). More preferably, it is 0.3-1.2 micrometers, More preferably, it is 0.5-1.0 micrometer, Most preferably, it is 0.8-1.0 micrometer. The above range is preferable from the viewpoints of peeling performance and prevention of uneven transfer to the adhesive layer.
Here, since the value obtained by the measurement method of the center plane average roughness (Ra) differs depending on the measurement method and measurement conditions, in the present invention, the stylus type surface defined in JIS-B-0651 (1976). Measure with a roughness meter. The measurement conditions of the measuring instrument are: the radius of curvature of the stylus tip is 5 μm, the cutoff wavelength is 0.80 mm, the cutoff type is 2CR (phase compensation), the measurement speed is 0.3 mm / second, the measurement direction is the film MD direction, and the measurement The length was 2 mm, and the range of surface roughness was defined by the obtained value. The MD direction, which is the measurement direction, refers to the film feed direction when extruding a resin composition containing a propylene-ethylene block copolymer as a main component, that is, the direction parallel to the longitudinal direction of the film.

Examples of polyolefin resins used for the release treatment layer include propylene homopolymers (homopolypropylene), propylene resins such as propylene / α-olefin random copolymers, propylene / α-olefin block copolymers, high-density polyethylene, and high pressure. Examples of the radical polymerization method include polyethylene resins such as low density polyethylene, linear low density polyethylene, and low density polyethylene.
Propylene homopolymers (homopolypropylene), propylene / α-olefin random copolymers, propylene / α-olefin block copolymers are generally present using catalysts such as Ziegler catalysts and metallocene catalysts. Below, it is produced by a polymerization method such as a slurry method using an inert solvent, a solution method, a gas phase method substantially using no solvent, or a bulk polymerization method using a polymerization monomer as a solvent. Moreover, ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene etc. are mentioned as an alpha olefin of a copolymerization component. The α-olefin may be used alone or in combination of two or more.
High-density polyethylene generally uses a catalyst such as a Ziegler catalyst, a Phillips catalyst, or a metallocene catalyst, and is a process such as a gas phase method, a solution method, a high-pressure method, or a slurry method. It is produced by (co) polymerizing with α-olefins such as -butene, 1-hexene, 4-methyl-1-pentene, 1-octene.
High-pressure radical polymerization method Low-density polyethylene uses ethylene or ethylene and a small amount of propylene, 1-butene, 1-hexene, 4-methyl in a process such as a high-pressure radical polymerization method using a radical generator such as peroxide as a polymerization initiator. It is produced by (co) polymerizing α-olefins such as -1-pentene and 1-octene.
Linear low-density polyethylene generally uses a catalyst such as a Ziegler catalyst, a Phillips catalyst, or a metallocene catalyst, and processes such as a gas phase method, a solution method, a high-pressure method, and a slurry method with ethylene and propylene, 1-butene. , 1-hexene, 4-methyl-1-pentene, 1-octene and other α-olefins are copolymerized. The α-olefin may be used alone or in combination of two or more.
The low density polyethylene is preferably a high pressure radical polymerization method low density polyethylene from the viewpoint of moldability.

  Moreover, the polyolefin resin used for the release treatment layer can be preferably used alone or a resin composition in which two or more polyolefin resins are combined. The blending amount and the basic physical properties of the resin are the same as those of the film of the present invention. The center plane average surface roughness (Ra) of the surface of the release treatment layer is preferably in the range of 0.2 to 1.5 μm, and in a combination of polyethylene resins, preferably 100 to 5% by weight of low density polyethylene High-density polyethylene 0 to 95% by weight, more preferably low-density polyethylene 100 to 20% by weight, high-density polyethylene 0 to 80% by weight, and still more preferably low-density polyethylene 100 to 50% by weight, high-density polyethylene 0 to A polyethylene resin composition containing 50% by weight. The melt flow rate (MFR; based on JIS-K6922-2: 1997, measured at 190 ° C. and 21.18 N load) of the polyethylene-based resin is 0.1 to 40 g / 10 minutes, preferably 0.3. -25 g / 10 min, more preferably 1.0-10 g / 10 min.

  Moreover, when mixing a propylene-type resin and a polyethylene-type resin and using it as a peeling process layer, Preferably, the propylene-type resin 95-50 weight%, the polyethylene-type resin 5-50 weight%, More preferably, the propylene-type resin 95 It is a resin composition containing -70 wt% and polyethylene resin 5-30 wt%.

  In the combination of propylene-based resins, preferably, the propylene homopolymer is 95 to 0% by weight, the propylene / α-olefin block copolymer is 5 to 100% by weight, and more preferably, the propylene homopolymer is 95 to 50% by weight. %, A resin composition containing 5 to 50% by weight of a propylene / α-olefin block copolymer. Further, the propylene / α-olefin random copolymer is 95 to 0% by weight, the propylene / α-olefin block copolymer is 5 to 100% by weight, and more preferably, the propylene / α-olefin random copolymer is 95 to 50% by weight. And a resin composition containing 5 to 50% by weight of a propylene / α-olefin block copolymer.

  The melt flow rate (MFR; measured in accordance with JIS K-7210-1995, measured at 230 ° C. under a load of 21.18 N) of the propylene-based resin used for the release treatment layer suppresses roughening of the interface with the base material layer. Therefore, a melt flow rate (MFR) close to the propylene-based resin used for the base material layer is preferable, and the melt flow rate (MFR) is 1 to 50 g / 10 minutes, preferably 2 to 30 g / 10 minutes. More preferably, it is 5-20 g / 10min, Most preferably, it is 7-15 g / 10min. Further, in the combination of propylene resin and polyethylene resin used for the release treatment layer, the melt flow rate (MFR) of propylene resin and the melt flow rate (MFR of polyethylene resin) are based on JIS-K6922-2: 1997. , 190 ° C. and a value measured at a load of 21.18 N), if the MFR is too different, the compatibility becomes extremely poor and causes fish eyes. Therefore, the melt flow rate (MFR) of the polyethylene resin is It is 0.1-40 g / 10min, Preferably it is 0.3-25g / 10min, More preferably, it is 1.0-10g / 10min.

  The low density polyethylene has a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) determined by gel permeation chromatography (GPC) of 4.0 to 8.0. Is preferred. When Mw / Mn is 4.0 to 8.0, the outer layer-adhesive delamination property is excellent.

In particular, the polyethylene resin or the like used for the release treatment layer preferably has a D hardness of 50 or more in order to prevent the film surface from being damaged during transportation and transportation.
Here, D hardness is a value measured according to JIS K7215.

Since the D hardness of the polyolefin resin is listed in a product pamphlet created by a polyolefin resin manufacturer or a polyolefin resin sales company, it can be selected from those commercially available products. The D hardness of a resin composition in which two or more polyolefin resins are combined can be predicted by an addition rule calculation from the D hardness and composition ratio of each polyolefin resin. In general, the D hardness is considered to change according to the crystallinity of the polyolefin resin. Among the polyolefin-based resins, the polyethylene-based resin has a high density polyethylene and tends to decrease as the density decreases. Moreover, propylene homopolymer is high in a propylene-type resin, and it becomes low as the quantity of a copolymerization component increases.
In the present invention, it is preferable to select in consideration of other performances (formability, interlayer strength with intermediate layer, etc.) within a range where D hardness is 50 or more. From the viewpoint of molding processability, it is preferably a resin composition containing 5 to 100% by weight of high-pressure radical polymerization method low-density polyethylene and 0 to 95% high-density polyethylene. High-pressure radical polymerization method with excellent moldability By blending low-density polyethylene and high-density polyethylene with high D hardness, it is possible to form an outer layer with good moldability and high hardness. Other preferred embodiments include linear low density polyethylene having a density of 0.925 g / cm ³ or more. The advantage is increased film strength.

4). Resin compounding agent that can be used in each layer The base material layer, the pressure-sensitive adhesive layer, and the release treatment layer used as necessary in the present invention include a film-forming stability, a film for surface protection, and a film for surface protection. From the maintenance of quality, as long as the purpose of the present invention is not impaired, various additives used as known resin compounding agents, such as antioxidants, antiblocking agents, slip agents, nucleating agents, neutralizing agents, It may contain a light stabilizer, antistatic agent, tackifier and the like. Various additives are described in detail below.

(1) Antioxidants As antioxidants, specific examples of phenolic antioxidants include tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, 1,1,3- Tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis {3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate}, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10- Examples thereof include tetraoxaspiro [5,5] undecane, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid and the like.

Specific examples of phosphorus antioxidants include tris (mixed, mono and dinonylphenyl phosphite), tris (2,4-di-t-butylphenyl) phosphite, 4,4′-butylidenebis (3- Methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-tert-butylphenyl) butane, bis (2, 4-di-t-butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2,4-di-t -Butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phos Or the like can be mentioned a fight.
Specific examples of the sulfur-based antioxidant include di-stearyl-thio-di-propionate, di-myristyl-thio-di-propionate, pentaerythritol-tetrakis- (3-lauryl-thio-propionate), and the like. it can.
These antioxidants can be used singly or in combination of two or more as long as the effects of the present object are not impaired.

  The compounding quantity of antioxidant is 0.01-1.0 weight part with respect to 100 weight part of each resin used for each layer of a base material layer, an adhesive layer, and a peeling process layer, Preferably it is 0.02-0. 0.5 part by weight, more preferably 0.05 to 0.1 part by weight. When the blending amount of the antioxidant is within the above range, the thermal stability is improved and the deterioration of the resin causing fish eyes is suppressed.

(2) Antiblocking agent The average particle diameter of an antiblocking agent is 1-7 micrometers, Preferably it is 1-5 micrometers, More preferably, it is 1-4 micrometers. If the average particle diameter is less than 1 μm, the slipperiness and openability of the resulting film are inferior. On the other hand, if it exceeds 7 μm, the transparency and scratching property are remarkably inferior. Here, the average particle diameter is a value obtained by Coulter counter measurement.

Specific examples of the anti-blocking agent include, for example, inorganic or synthetic silica (silicon dioxide), magnesium silicate, aluminosilicate, talc, zeolite, aluminum borate, calcium carbonate, calcium sulfate, barium sulfate, calcium phosphate. Etc. are used.
Moreover, as an organic type, polymethyl methacrylate, polymethylsilyltosesquioxane (silicone), polyamide, polytetrafluoroethylene, epoxy resin, polyester resin, benzoguanamine / formaldehyde (urea resin), phenol resin, etc. may be used. it can.
In particular, synthetic silica and polymethyl methacrylate are preferable from the balance of dispersibility, transparency, blocking resistance, and scratch resistance.
The anti-blocking agent may be surface-treated, and as the surface treating agent, surfactant, metal soap, acrylic acid, oxalic acid, citric acid, tartaric acid and other organic acids, higher alcohols, esters, Condensed phosphates such as silicone, fluorine resin, silane coupling agent, sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, sodium trimetaphosphate, etc. can be used, especially those treated with citric acid among organic acids Is preferred. The treatment method is not particularly limited, and a known method such as surface spraying or dipping can be employed.
The anti-blocking agent may have any shape, and can be any shape such as a spherical shape, a square shape, a columnar shape, a needle shape, a plate shape, and an indefinite shape.
These anti-blocking agents can be used singly or in combination of two or more in a range that does not impair the effects of this object.

  The compounding amount of the anti-blocking agent is 0.01 to 1.0 part by weight, preferably 0.05 to 0 with respect to 100 parts by weight of each resin used in each layer of the base material layer, the pressure-sensitive adhesive layer and the release treatment layer. 0.7 parts by weight, more preferably 0.1 to 0.5 parts by weight. When the blending amount of the anti-blocking agent is within the above range, the blocking property is improved and the feeding property is improved.

(3) Slip agent Examples of the slip agent include monoamides and bisamides, and these may be substituted. Among these, it can be used 1 type or in combination of 2 or more types.
Specific examples of monoamides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like as saturated fatty acid monoamides.
Examples of the unsaturated fatty acid monoamide include oleic acid amide, erucic acid amide, ricinoleic acid amide and the like.
Specific examples of substituted amides among monoamides include N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl Examples include palmitic acid amide.
Specific examples of bisamides include, as saturated fatty acid bisamides, methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bis stearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, Ethylene bis behenic acid amide, hexamethylene bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bishydroxy stearic acid amide, m-xylylene bis stearic acid amide and the like.
Examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide and hexamethylene bisoleic acid amide.
Among these, oleic acid amide, erucic acid amide, and behenic acid amide are particularly preferably used among the fatty acid amides.
Specific examples of substituted amides among bisamides include N, N′-distearyladipate amide, N, N′-distearylsepacate amide, N, N′-dioleyl adipate amide, N, N ′ -Dioleyl sepasin acid amide, N, N'-distearylisophthalic acid amide and the like.

  As a compounding quantity of a slip agent, 0.01-1.0 weight part with respect to 100 weight part of each resin used for each layer of a base material layer, an adhesive layer, and a peeling process layer, Preferably 0.05- 0.7 part by weight, more preferably 0.1 to 0.4 part by weight. When the blending amount of the slip agent is within the above range, the slipping property is improved and the feeding property is improved.

(4) Nucleating agent Specific examples of the nucleating agent include sodium 2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate, talc, 1,3,2,4-di (p-methyl). A sorbitol compound such as benzylidene) sorbitol, hydroxy-di (t-butylaluminum benzoate), 2,2-methylene-bis (4,6-di-t-butylphenyl) phosphoric acid and an aliphatic mono-carbon having 8 to 20 carbon atoms. Examples thereof include a carboxylic acid lithium salt mixture (manufactured by ADEKA, trade name NA21).
As a compounding quantity of the said nucleating agent, 0.0005-0.5 weight part with respect to 100 weight part of each resin used for each layer of a base material layer, an adhesive layer, and a peeling process layer, Preferably it is 0.001. It is -0.1 weight part, More preferably, it is 0.005-0.05 weight part. When the blending amount of the nucleating agent is within the above range, the crystallization speed is increased and the transparency is improved.

Moreover, a high density polyethylene resin can be mentioned as a nucleating agent other than the above. The density of the high-density polyethylene resin is 0.94 to 0.98 g / cm ³ , preferably 0.95 to 0.97 g / 10 cm ³ . If the density is out of this range, the effect of improving transparency cannot be obtained. 190 degreeC melt flow rate (MFR) of a high density polyethylene resin is 5 g / 10min or more, Preferably it is 7-500 g / 10min, More preferably, it is 10-100 g / 10min. When the MFR is less than 5 g / 10 min, the dispersion diameter of the high-density polyethylene resin is not sufficiently small, and it itself becomes a foreign matter and causes fish eyes. In order to finely disperse the high-density polyethylene resin, the MFR of the high-density polyethylene resin is preferably larger than the MFR of the propylene-based resin of the present invention.

  The production of the high-density polyethylene resin used as the nucleating agent is not particularly limited with respect to the polymerization method and catalyst as long as a polymer having the desired physical properties can be produced. For catalysts, Ziegler type catalysts (ie, based on a combination of supported or unsupported halogen-containing titanium compounds and organoaluminum compounds), Kaminsky type catalysts (ie, supported or unsupported metallocene compounds and organoaluminum compounds, especially alumoxanes). Based on the combination). There is no restriction | limiting about the shape of a high density polyethylene-type resin, A pellet form may be sufficient and a powder form may be sufficient.

  The blending amount of the high density polyethylene used as the nucleating agent is 0.01 to 5 parts by weight, preferably 100 parts by weight of each resin used in each layer of the base material layer, the pressure-sensitive adhesive layer and the release treatment layer. 0.05 to 3 parts by weight, more preferably 0.1 to 1 part by weight. When the blending amount of the high density polyethylene is within the above range, the crystallization speed is increased and the transparency is improved. Further, in the case of coextrusion molding, there is no transfer of the sweeper roll.

(5) Neutralizing agent Specific examples of the neutralizing agent include calcium stearate, zinc stearate, hydrotalcite, Mizukarak (manufactured by Mizusawa Chemical Co., Ltd.), and the like.
The blending amount of the neutralizing agent is 0.01 to 1.0 parts by weight, preferably 0.02 to 0 parts per 100 parts by weight of each resin used in each of the base layer, the pressure-sensitive adhesive layer and the release treatment layer. 0.5 part by weight, more preferably 0.05 to 0.1 part by weight. When the blending amount of the neutralizing agent is within the above range, the effect as an internal lubricant is improved, and scraping of deteriorated materials inside the extruder is suppressed.

(6) Light Stabilizer As the light stabilizer, a hindered amine stabilizer is preferably used, and a structure in which all hydrogen bonded to carbons at the 2-position and 6-position of a conventionally known piperidine is substituted with a methyl group. Although the compound which has this is used without being specifically limited, the following compounds are specifically used.
Specific examples include polycondensates of dimethyl oxalate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, tetrakis (1,2,2,6,6). -Pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, N, N-bis (3-aminopropyl) ) Ethylenediamine · 2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4- Jil} {(2,2, , 6-tetramethyl-4-piperidyl) imino} hexamethylene {2,2,6,6-tetramethyl-4-piperidyl} imino], poly [(6-morpholino-s-triazine-2,4-diyl) [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidi) and the like.
These hindered amine stabilizers can be used singly or in combination of two or more in a range not impairing the effect of the present object.

The blending amount of the hindered amine stabilizer is 0.005 to 2 parts by weight, preferably 0.01 to 1 part by weight with respect to 100 parts by weight of each resin used in the base layer, the pressure-sensitive adhesive layer and the release treatment layer. Parts, more preferably 0.05 to 0.5 parts by weight.
When the content of the hindered amine stabilizer is within the above range, stability such as heat resistance and aging resistance is improved.

(7) Antistatic agent The antistatic agent can be used without particular limitation as long as it is a known antistatic agent or antistatic agent conventionally used, and examples thereof include anionic surfactants and cations. Ionic surfactants, nonionic surfactants, amphoteric surfactants and the like.

  Examples of the anionic surfactant include fatty acid or rosin acid soap, N-acyl carboxylate, ether carboxylate, carboxylate such as fatty acid amine salt; sulfosuccinate, ester sulfonate, N-acyl sulfonate Sulfonates such as salts; sulfated oils, sulfate esters, alkyl sulfate salts, sulfate sulfate polyoxyethylene salts, sulfate ether salts, sulfate ester salts such as sulfate amide salts; alkyl phosphate salts, alkyl polyoxyethylene phosphates Examples thereof include phosphoric acid ester salts such as salts, phosphoric acid ether salts and phosphoric acid amide salts.

  Examples of the cationic surfactant include amine salts such as alkylamine salts; alkyltrimethylammonium chloride, alkylbenzyldimethylammonium chloride, alkyldihydroxyethylmethylammonium chloride, dialkyldimethylammonium chloride, tetraalkylammonium salt, N, N-di Quaternary ammonium salts such as (polyoxyethylene) dialkylammonium salts and N-alkylalkanamide ammonium salts; 1-hydroxyethyl-2-alkyl-2-imidazoline, 1-hydroxyethyl-1-alkyl-2-alkyl Examples include alkyl imidazoline derivatives such as -2-imidazoline; imidazolinium salts, pyridinium salts, isoquinolinium salts, and the like.

  Examples of the nonionic surfactant include ether forms such as alkyl polyoxyethylene ether and p-alkylphenyl polyoxyethylene ether; fatty acid sorbitan polyoxyethylene ether, fatty acid sorbitol polyoxyethylene ether, fatty acid glycerin polyoxyethylene ether, etc. Ether ester form of fatty acid polyoxyethylene ester, monoglyceride, diglyceride, sorbitan ester, sucrose ester, dihydric alcohol ester, boric acid ester, etc .; dialcohol alkylamine, dialcohol alkylamine ester, fatty acid alkanolamide, N, N-di (polyoxyethylene) alkanamide, alkanolamine ester, N, N-di (polyoxyethylene) alkaneamine, amine oxy De, a nitrogen-formed and fabricated and alkyl polyethylene imine.

  Examples of the amphoteric surfactant include amino acid forms such as monoaminocarboxylic acid and polyaminocarboxylic acid; N-alkyl-β-alanine such as N-alkylaminopropionate and N, N-di (carboxyethyl) alkylamine salt. Forms: Betaine forms such as N-alkylbetaines, N-alkylamidobetaines, N-alkylsulfobetaines, N, N-di (polyoxyethylene) alkylbetaines, imidazolinium betaines; 1-carboxymethyl-1-hydroxy- And alkyl imidazoline derivatives such as 1-hydroxyethyl-2-alkyl-2-imidazoline and 1-sulfoethyl-2-alkyl-2-imidazoline.

  Among these, nonionic surfactants and amphoteric surfactants are preferable. Among them, monoglycerides, diglycerides, boric acid esters, dialcohol alkylamines, dialcohol alkylamine esters, amides and the like or nitrogen-containing non-type surfactants are preferred. Ionic surfactants; betaine amphoteric surfactants are preferred.

  In addition, as an antistatic agent, a commercial item can be used, for example, electro stripper TS5 (trade name, glycerin monostearate manufactured by Kao Corporation), electro stripper TS6 (trade name, stearyl manufactured by Kao Corporation). Diethanolamine), electro stripper EA (trade name, lauryl diethanol amine, manufactured by Kao Corporation), electro stripper EA-7 (trade name, polyoxyethylene lauryl amine capryl ester, manufactured by Kao Corporation), Denon 331P (maruhishi oil ( Co., Ltd., trademark, stearyl diethanolamine monostearate), Denon 310 (manufactured by Maruhishi Oil Chemical Co., Ltd., trademark, alkyldiethanolamine fatty acid monoester), Register PE-139 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trademark) , Stearic acid mono & diglyceride Ester), Chemistat 4700 (Sanyo Chemical Industries Co., Ltd., trademark, alkyl dimethyl betaine), rheostat S (Lion Co., Ltd., trademark, alkyl diethanolamide), and the like.

  The blending amount of the antistatic agent is 0.01 to 2 parts by weight, preferably 0.05 to 1 part by weight with respect to 100 parts by weight of each resin used for each layer of the base material layer, the pressure-sensitive adhesive layer and the release treatment layer. More preferably, it is 0.1-0.8 weight part, Most preferably, it is 0.2-0.5 weight part. These antistatic agents can be used singly or in combination of two or more in a range that does not impair the effects of this object. When the blending amount of the antistatic agent is within the above range, it is possible to prevent electrification and suppress deposits such as dust.

(8) Tackifiers Examples of tackifiers include aliphatic petroleum resins, alicyclic hydrogenated petroleum resins, aromatic petroleum resins, C5 petroleum resins, terpene resins, coumarone / indene resins, and phenol resins. Rosin resin, tackifier and the like, and these can be used singly or in combination of two or more without departing from the significant effect of the present invention.

  The compounding amount of the tackifier is not particularly limited as long as the effects of the present invention are not impaired, but with respect to 100 parts by weight of each resin used for each layer of the base material layer, the pressure-sensitive adhesive layer and the release treatment layer. 0.0001 to 200 parts by weight. Preferably it is 0.01-150 weight part, More preferably, it is 1-150 weight part, Most preferably, it is 10-100 weight part. When the compounding amount of the tackifier is within the above range, the adhesive strength is improved.

(9) Others Further, an elastomer is blended as a component for imparting flexibility, an ultraviolet absorber, a metal deactivator, a peroxide, a filler, an antibacterial and antifungal agent, as long as the effects of the present invention are not significantly impaired. Agents, fluorescent brighteners, antifogging agents, flame retardants, colorants, pigments, natural oils, synthetic oils, waxes and the like can be blended, and the blending ratio is an appropriate amount.

The blending of the above various additives can be directly added to the propylene resin of the present invention obtained by polymerization and melt kneaded for use, or may be added during melt kneading. Furthermore, it can be added directly after melt-kneading, or can be added as a masterbatch within a range that does not significantly impair the effects of the present invention. Moreover, you may add by these composite methods.
In general, additives such as an antioxidant and a neutralizing agent are blended, mixed, melted and kneaded, and then molded into a product for use. It is also possible to add and use other resins or other additional components (including a masterbatch) as long as the effects of the present invention are not significantly impaired during molding.

  For the above mixing, melting, and kneading, any conventionally known method can be used. Usually, Henschel mixer, super mixer, V blender, tumbler mixer, ribbon blender, Banbury mixer, kneader blender, uniaxial or biaxial kneading. It can be carried out in an extruder. Among these, it is preferable to perform mixing or melt-kneading with a uniaxial or biaxial kneading extruder.

5. Production of Surface Protection Film The surface protection film of the present invention can be produced by a known method for producing a laminated film.
For example, it manufactures by well-known techniques, such as a T die-cast method, a water cooling inflation method, an air cooling inflation method.
In particular, as the T die casting method, a resin melted and kneaded by an extruder is extruded from the T die and cooled by being brought into contact with a roll through a refrigerant such as water, thereby producing a film. However, it is generally possible to produce a film having good transparency and good thickness accuracy. Such a method is a preferable manufacturing method for the film.

  Here, the thickness of the film for surface protection is not particularly limited, but is 10 to 500 μm, preferably 20 to 200 μm, more preferably 30 to 100 μm, and most preferably 40 to 80 μm. If the thickness is outside this range, processing becomes difficult.

  As a method of obtaining the pressure-sensitive adhesive layer by lamination, the pressure-sensitive adhesive is heated and melted by an extruder, extruded into a film form from a T-die, and laminated on one side of the base material layer, or the base material layer and Examples thereof include a method in which an adhesive is heated and melted and coextruded in a film form from a T die together with a base material layer.

  The thickness of the pressure-sensitive adhesive layer is not particularly limited because the adhesive strength varies depending on the application, but is usually 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 5 to 30 μm, and most preferably 10 to 20 μm. .

Examples of means for forming a release treatment layer provided on the other side of the pressure-sensitive adhesive layer of the surface protective film of the present invention include known methods such as coating, curing, and lamination.
As a method for obtaining the release treatment layer by coating, a release treatment agent dissolved in an organic solvent such as a toluene solution is applied to one side of the base material layer with a roll coater, and then dried to cure the release treatment agent and release. The method of forming a process layer can be mentioned. At that time, in order to improve the affinity between the base material layer and the release treatment layer, conventionally known corona discharge treatment, plasma discharge treatment, primer treatment, etc. are performed on one side of the base material layer (adhesion surface with the release treatment layer). May be.
Moreover, as a method for obtaining a release treatment layer by lamination, a method of laminating a release treatment agent into a polyolefin-based resin and melting it with an extruder, and laminating it on a single side of a base material layer from a T-die, Alternatively, a method of heating and melting a release treatment layer in which a release treatment agent is blended with a base material layer and a polyolefin-based resin by an extruder, and coextruding into a film shape from a T die together with the base material layer can be exemplified. .
In the present invention, adopting a method of roughening the surface of the release treatment layer to form unevenness and imparting release properties is advantageous in terms of contamination problems and economical points, and is suitable for the production of the release treatment layer. In addition, a method of co-extrusion with a T-die and lamination is preferable.

For method of applying the release treatment layer in a subsequent step, the coating amount of the release agent is generally in the case of silicone, 0.01 to 10 g / ^{m 2,} preferably from 0.1 to 3 g / ^{m 2.} In the case of long-chain alkyl-based, 0.005~10g / ^{m 2,} preferably 0.02~0.3g / ^{m 2,} particularly preferably preferably 0.01 to 0.1 g / ^{m 2.}

  In the case of laminating by heating and melting with an extruder, the thickness of the release treatment layer is not particularly limited, but is usually 0.1 to 100 μm, preferably 1 to 50 μm, more preferably 5 to 30 μm, most preferably. Is 10-20 μm.

6). Use of surface protective film The surface protective film of the present invention is stuck so that the pressure-sensitive adhesive layer is in contact with the surface of the adherend. Examples of the adherend include building members and liquid crystal display components. Examples of the building member include a synthetic resin plate, a decorative plate, a metal plate, and a glass plate. Moreover, as a structural member of a liquid crystal display, a polarizing plate, a phase difference plate, etc. are mentioned.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. The physical property measurement methods, characteristic evaluation methods, and resin materials used in Examples and Comparative Examples are as follows.

1. Physical property measurement method, characteristic evaluation method (1) MFR: Propylene resin is measured at 230 ° C. under a load of 21.18 N in accordance with JIS K-7210-1995, and ethylene / α-olefin copolymer is measured according to JIS K-6922-2: Measured at 190 ° C. under a load of 21.18 N in accordance with the appendix of 1997.
(2) Density: Measured according to JIS K-6922-2: 1997 appendix (23 ° C.).
(3) Melting peak temperature: Using a differential scanning calorimeter (Seiko DSC), a sample amount of 5.0 mg was taken, held at 200 ° C. for 5 minutes, and then crystallized at a rate of temperature decrease of 10 ° C./min to 40 ° C. And the melting peak temperature (Tmp) when melted at a heating rate of 10 ° C./min was measured.
(4) Weight average molecular weight (Mw) / Number average molecular weight (Mn): Measured by the method described above.
(5) Temperature rising elution fractionation method: Measured by the method described above.
(6) n-decane soluble content: 200 ml of n-decane was added to 5 g of the sample and heated while stirring to completely dissolve the sample. It was cooled to 20 ° C. over about 3 hours and left for 30 minutes. Thereafter, the precipitate was filtered off. The filtrate was put in 1000 ml of acetone to precipitate the components dissolved in n-decane. The precipitate and acetone were filtered off and the precipitate was dried. Even when the filtrate side was concentrated to dryness, no residue was observed. The amount of n-decane solubles was determined by the following formula.
n-decane soluble content (% by weight) = [precipitate weight / sample weight] × 100
(7) Haze: The film was conditioned at 23 ° C. and 50% RH for 24 hours, and then measured with a haze meter in accordance with JIS-K7136-2000. The smaller the value obtained, the better the transparency.
(8) Tensile elastic modulus: The film was measured for tensile elastic modulus in the flow direction (MD) under the following conditions in accordance with ISO 527.
The higher the obtained numerical value, the higher the rigidity of the film and the easier it is to handle it as a surface protecting film.
Sample length: 150mm
Sample width: 10mm
Distance between chucks: 100mm
Crosshead speed: 25mm / min
(9) Fish Eye: The number of fish eyes was counted from the area of 1 m ^{2 of the} film. The obtained fish eye is visually observed to have a major axis of 0.4 mm or more (≧ 0.4 mm), smaller than 0.4 mm, 0.2 mm or more (<0.4 mm to ≧ 0.2 mm), smaller than 0.2 mm, and 0. Each size was classified into 1 mm or more (<0.2 mm to ≧ 0.1 mm), and the number of each was divided (unit: pieces / m ² ).
When the number of fish eyes is small, even if the surface protective film is attached to the object to be protected and stacked and stored, the object to be protected does not dent, and is better as the surface protective film.
(10) Tackiness: Acrylic resin plate (mirror surface acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd. “Acrylic”), which has a longitudinal direction of the film, cut to a width of 25 mm and a length of 20 cm, and heated to 60 ° C. LIGHT L001 ”3 mm plate) After aging the pasted film at a temperature of 23 ° C. and a humidity of 50% for 12 hours, in accordance with JIS Z0237, at a pulling speed of 300 mm / min, at a peeling angle of 180 ° C. The adhesive strength per 25 mm width was measured.
The higher the value, the higher the adhesive strength. Although the target strength varies depending on the adherend, the adhesive strength is generally used in the range of 1 to 400 g / 25 mm. If the adhesive strength is too low, bonding to the adherend cannot be performed. If the adhesive strength is too high, it cannot be easily peeled off from the adherend.
(11) Outer layer-adhesive delamination property: Usually, the surface protective film is wound around a paper tube in a form in which the release treatment layer and the adhesive layer are in contact with each other, fed out and adhered to a product. As an evaluation of unwinding property, the formed film can be rolled up in a form in which the outer layer and the adhesive layer are in contact with a 3-inch paper tube, and when unrolled at 20m / min, it can be unwound smoothly without wrinkles or sagging. These were visually checked, and those that could be smoothly fed were marked with ◯, and those that could not be smoothly fed were marked with X.
(12) Delamination (Punching impact strength): Using a “puncture tester” tester manufactured by Toyo Seiki, punching was performed using a 1/2 inch hemispherical head, visually confirmed, and those that did not peel Those with peeling were marked with x.

2. Resin material (1) Propylene resin As propylene resin, propylene-ethylene random copolymer (Wintech WFX4 (manufactured by Nippon Polypro), Wintech WFW4 (manufactured by Nippon Polypro)), Ziegler catalyst with metallocene catalyst Propylene / ethylene / butene random copolymer (Novatech PP FW4B (manufactured by Nippon Polypro Co., Ltd.)) and propylene / ethylene random copolymer (Novatech PP FX3A (manufactured by Nippon Polypro Co., Ltd.)) with Ziegler catalyst were used. Table 1 shows the physical properties.

  As propylene-based resin polymerized using a metallocene catalyst, using a T-die method film production apparatus comprising WFX4, WFW4, FX3A, FW4B as raw materials, a 35 mmφ extruder, a 330 mm wide die, an air knife and a cooling roll, The film was formed at a film take-up speed of 10 m / min under the conditions of a T-die lip clearance of 0.8 mm, an extruder cylinder set temperature of 230 ° C., and a cooling roll temperature of 35 ° C. to obtain a film with a film thickness of 40 μm. It was. The characteristic of the propylene-type resin film (base material layer) was evaluated from the obtained film. The results are shown in Table 2.

(2) Ethylene / α-olefin copolymer As the ethylene / α-olefin copolymer, the ethylene / α-olefin random copolymer (PE-1 to 3) obtained in the following Production Examples 1 to 3 using a metallocene catalyst. Was used. Table 3 shows the physical properties.

(Production Example 1)
The catalyst was prepared by the method described in JP-T-7-508545. That is, to the complex dimethylsilylene bis (4,5,6,7-tetrahydroindenyl) hafnium dimethyl 2.0 mmol, tripentafluorophenyl boron was added in an equimolar amount to the above complex, and diluted to 10 liters with toluene. A catalyst solution was prepared. A stirring autoclave type continuous reactor having an internal volume of 1.5 liters was maintained at a pressure of 130 MPa, and a mixture of ethylene and 1-hexene was 40 kg / hour so that the composition of 1-hexene was 73% by weight. Continuously. Further, the catalyst supply amount was adjusted so that the polymerization temperature was maintained at 127 ° C. The polymer production per hour was about 2.1 kg. After completion of the reaction, ethylene 1-hexene having an MFR of 3.5 g / 10 min, a density of 0.880 g / cm ³ , an Mw / Mn of 2.0, and an elution amount of TREF of 20 ° C. or lower of 12.3% by weight A copolymer (PE1) was obtained. The obtained ethylene / 1-hexene copolymer (PE1) was pelletized at an extrusion temperature of 230 ° C. using a 50 mmφ single screw extruder to obtain an adhesive resin (PE-1).

(Production Example 2)
In Production Example 1, the conditions were changed so that the polymerization temperature was 144 ° C. and the composition of 1-hexene in the mixture of ethylene and 1-hexene was 63% by weight, and an ethylene / 1-hexene copolymer (PE2 ) The obtained ethylene / 1-hexene copolymer (PE2) was pelletized at an extrusion temperature of 230 ° C. using a 50 mmφ single screw extruder to obtain an adhesive resin (PE-2). Table 3 shows the physical properties.

(Production Example 3)
In Production Example 1, the conditions were changed so that the polymerization temperature was 156 ° C., and the composition of 1-hexene in the mixture of ethylene and 1-hexene was 54% by weight, and an ethylene / 1-hexene copolymer (PE3 ) The obtained ethylene / 1-hexene copolymer (PE3) was pelletized at an extrusion temperature of 230 ° C. using a 50 mmφ single screw extruder to obtain an adhesive resin (PE-3). Table 3 shows the physical properties.

(3) Thermoplastic styrene-diolefin copolymer hydrogenated product As a thermoplastic styrene-diolefin copolymer hydrogenated product, styrene block-butadiene block-styrene block copolymer hydrogenated product (SEBS-) shown in Table 4 1) to (SEBS-3) were used.

Example 1
Using a T-die two-layer coextrusion film production apparatus equipped with a 35 mmφ extruder, a 20 mmφ extruder, a 300 mm wide T die, an air knife and a cooling roll, a propylene resin as a raw material for a substrate layer in a 35 mmφ extruder (WFX4), 20 mmφ extruder, PE-1: 80 wt% and SEBS-3: 20 wt% mixture as raw material for adhesive layer, T die lip clearance 0.8mm, extruder Under the conditions of a cylinder set temperature of 230 ° C. and a cooling roll temperature of 35 ° C., two layers are unstretched by coextrusion so that the substrate layer thickness is 40 μm and the adhesive layer thickness is 10 μm at a film forming take-up speed of 10 m / min. A protective film made of a film was formed. Table 5 shows the evaluation results of the obtained surface protective film.

(Example 2)
A surface protective film was molded under the same conditions as in Example 1 except that WFW4 was used as the propylene-based resin used for the base material layer. Table 5 shows the evaluation results of the obtained surface protective film.

(Example 3)
A surface protective film was molded under the same conditions as in Example 2 except that a mixture of PE-2: 80% by weight and SEBS-1: 20% by weight was used as the pressure-sensitive adhesive layer. Table 5 shows the evaluation results of the obtained surface protective film.

Example 4
A surface protective film was molded under the same conditions as in Example 2 except that a mixture of PE-2: 80% by weight and SEBS-2: 20% by weight was used as the pressure-sensitive adhesive layer. Table 5 shows the evaluation results of the obtained surface protective film.

(Example 5)
A surface protective film was molded under the same conditions as in Example 2 except that a mixture of PE-1: 50% by weight and SEBS-3: 50% by weight was used as the pressure-sensitive adhesive layer. Table 5 shows the evaluation results of the obtained surface protective film.

(Comparative Example 1)
A surface protective film was molded under the same conditions as in Example 2 except that a mixture of PE-3: 80% by weight and SEBS-3: 20% by weight was used as the adhesive layer. Table 6 shows the evaluation results of the obtained surface protective film. This is inferior in transparency.

(Comparative Example 2)
A surface protective film was molded under the same conditions as in Example 2 except that a mixture of PE-1: 80% by weight and SEBS-1: 20% by weight was used as the adhesive layer. Table 6 shows the evaluation results of the obtained surface protective film. This is inferior in transparency.

(Comparative Example 3)
A surface protective film was molded under the same conditions as in Example 1 except that FX3A was used as the propylene-based resin used for the base material layer. Table 6 shows the evaluation results of the obtained surface protective film. This is inferior in delamination.

(Comparative Example 4)
A surface protective film was molded under the same conditions as in Example 1 except that FW4B was used as the propylene-based resin used for the base material layer. Table 6 shows the evaluation results of the obtained surface protective film. This is inferior in delamination.

  From the results of Tables 5 and 6, it can be seen that the surface protective film of the present invention has transparency characteristics, and is obtained by using an ethylene / α-olefin copolymer having specific physical properties in the adhesive layer. The surface protective film is excellent in transparency and rigidity, can give the desired adhesive strength by adjusting the density of the adhesive layer, and is excellent in pay-out property and has little or no delamination. (Examples 1 to 5).

  The film for surface protection of the present invention is made of a specific propylene resin, because the crystallinity distribution of the resin is narrow, the amount of low crystalline components eluted is small, the molecular weight distribution is narrow, and the high molecular weight component is small. There is very little unmelted fish eye during film forming. For this reason, even if a surface protection film is affixed on a to-be-protected object and stored in a stacked manner, the to-be-protected object does not dent. Therefore, it is suitably used as a surface protective film excellent in transparency of structural members for liquid crystal displays such as polarizing plates and retardation plates for surface protection of building members such as synthetic resin plates, decorative plates, metal plates and glass plates. can do.

Claims (5)

In the surface protective film in which the pressure-sensitive adhesive layer is formed on one surface of the base material layer made of propylene-based resin,
The propylene-based resin is a propylene homopolymer polymerized using a metallocene catalyst and has the following properties (A1) to (A4), or a propylene / α-olefin random copolymer,
The pressure-sensitive adhesive layer is polymerized using a metallocene catalyst, and an ethylene / alpha-olefin copolymer (component (B)) having the following properties (B1) to (B2): From an ethylene / α-olefin copolymer composition containing 5 to 95% by weight of a hydrogenated thermoplastic styrene-diolefin copolymer (component (C)) satisfying the condition (a) A film for protecting a surface.
(A1) Melt flow rate (MFR: 230 ° C., 21.18 N load) is 1 to 50 g / 10 minutes (A2) Melting peak temperature (Tmp) by differential thermal scanning calorimeter (DSC) is 120 to 170 ° C.
(A3) The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 1.5 to 3.5.
(A4) Atsushi Nobori elution fractionation (TREF) 40 ° C. The following solubles measured by method _{(S 40)} is 10 wt% or less (B1) Density [d] is 0.86 5 ~0.9 05 g / cm ³
(B2) weight average molecular weight (Mw) and the ratio of the number average molecular weight (Mn) (Mw / Mn) is 3.5 or less (C1) styrene content [St] 10 to 5 0 wt%
Condition (a): The density [d] (g / cm ³ ) of the component (B) and the styrene content [St] (wt%) of the component (C) satisfy the following formula (1) ″ .
640 [d] -555.2 <[St] <640 [d] -541.2 (1) " The film for surface protection according to claim 1, wherein the propylene-based resin further has the following property (A5).
(A5) The range (T ₁₀₀ -T ₂₀ ) of the temperature (T ₁₀₀ ) at the end of elution by 100 wt% from the temperature (T ₂₀ ) at the elution of 20 wt% by the temperature rising elution fractionation (TREF) method is 30 ° C. Less than   The surface protective film according to claim 1, wherein a pressure-sensitive adhesive layer is formed on one surface of the base material layer, and a release treatment layer is formed on the other surface.   The film for surface protection according to any one of claims 1 to 3, wherein the film is used for surface protection of a building member such as a synthetic resin plate, a decorative plate, a metal plate, and a glass plate.   The surface protecting film according to any one of claims 1 to 3, wherein the film is used for protecting a surface of a liquid crystal display component such as a polarizing plate or a retardation plate.