JP2015044970A - Surface protective film and optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective film having excellent whitening resistance, with superior appearance, capable of preventing deterioration of adhesiveness of an adherend surface to other laminate members such as interlayer filler, after removing a surface protective film.SOLUTION: A surface protective film includes: a base material having a first surface and a second surface; a top coat layer disposed on the first surface side of the base material; and an acrylic adhesive layer disposed on the second surface side of the base material. The top coat layer includes wax as a lubricant and a polyester resin as a binder. The wax is an ester of higher fatty acid and higher alcohol. The acrylic adhesive layer includes an acrylic polymer as a base polymer, and has a specific property.

Description

  The present invention relates to a surface protective film and an optical member.

  Conventionally, the surface of an optical member or the like is protected with a surface protective film (surface protective sheet) so that the surface of the optical member or the like is not soiled or scratched when the optical member or electronic member is transported or assembled. Is generally done. Examples of such a surface protective film include a surface protective film having a coating layer on one surface side of a substrate and an adhesive layer on the other surface side (Patent Documents 1 and 2).

JP 2009-107329 A JP 2011-20348 A

  As such a surface protective film, a transparent film is preferably used from the viewpoint that an appearance inspection of an adherend (for example, a polarizing plate) can be performed with the surface protective film attached. In recent years, from the viewpoint of the ease of appearance inspection and inspection accuracy, the required level for the appearance quality of the surface protection film has increased. For example, the back surface of the surface protection film (the surface to be attached to the adherend) There is a demand for the property that the surface on the opposite side is not easily scratched. This is because if the surface protective film has scratches, it cannot be determined whether the surface protective film is affixed with the surface protective film attached to the adherend or the surface protective film.

  One method for making the back surface of the surface protective film less susceptible to scratches is a method of providing a hard surface layer (top coat layer, coat layer) on the back surface. Such a topcoat layer is formed, for example, by applying a coating agent to the back surface of the substrate and drying and curing. It is advantageous that the top coat layer has an appropriate slipperiness in order to realize higher scratch resistance (scratch resistance, a characteristic that the surface is not easily scratched). This is because the slipperiness allows a stress that can be applied when the topcoat layer is rubbed to flow along the surface of the topcoat layer. Generally, a silicone-based lubricant (for example, a silicone compound such as polyether-modified polydimethylsiloxane) or the like is used as an additive (lubricant) for imparting slipperiness to the topcoat layer.

  However, the present inventors have found that a topcoat layer formed by adding a silicone-based lubricant has a phenomenon that the appearance becomes whitish (whitening) depending on the storage conditions (for example, when kept under high temperature and high humidity). We found that it is easy to produce. When the topcoat layer of the surface protective film is whitened, there arises a problem that the visibility of the adherend surface through the surface protective film is lowered. For example, there may be a problem that the inspection accuracy is deteriorated when the appearance inspection of the adherend is performed with the surface protective film attached.

Further, the surface protective film is peeled off from the optical member at the stage where the protection of the member surface becomes unnecessary, such as after the transporting process of the optical member. After the surface protective film is peeled off, a layer having another function (another layer) or the like may be provided on the adherend surface to which the surface protective film has been attached. Depending on the condition of the surface of the adherend after peeling off the surface protective film, the wettability to other layers may deteriorate, or the other layers may not adhere sufficiently to the adherend. In some cases, the layer failed to perform the expected function or the product was defective.
Specifically, when another layer such as a layer having a touch panel function or a protective layer made of glass or plastic is placed on the surface of the liquid crystal display, a polarizing plate on the surface of the liquid crystal display (for example, the surface layer is a hard coat layer). After removing the surface protective film provided to protect the surface of the polarizing plate, etc., an interlayer filler is applied between the other layer and the polarizing plate surface of the liquid crystal display surface to form a transparent layer. When provided, the wettability of the polarizing plate surface with respect to the interlayer filler and the adhesion between the polarizing plate surface and the interlayer filler may not be sufficient.

  That is, after the surface protective film is peeled off, when another layer is provided on the surface of the adherend to which the surface protective film has been attached, the surface of the adherend is excellent in wettability with respect to the other layer, and the surface of the adherend The surface protection film which can be made into the state which is excellent in adhesiveness with other layers is not known at present.

  Accordingly, the object of the present invention is to prevent the adhesion of the adherend surface to other laminated members such as an interlayer filler from being impaired after the surface protection film is peeled off, with excellent whitening resistance and good appearance. It is in providing the surface protection film which can be performed.

  As a result of intensive studies by the present inventors, a surface protective film provided with a topcoat layer containing a specific component on one side of the substrate and an acrylic pressure-sensitive adhesive layer having specific characteristics on the other side Is used, the surface protection film has excellent whitening resistance, good appearance, and can prevent the adherence of the adherend surface to other laminated members such as an interlayer filler from being peeled after the surface protection film is peeled off. The present invention was completed.

That is, the present invention is provided with a base material having a first surface and a second surface, a topcoat layer provided on the first surface side of the base material, and the second surface side of the base material. An acrylic pressure-sensitive adhesive layer, wherein the topcoat layer includes a wax as a slip agent and a polyester resin as a binder, and the wax is an ester of a higher fatty acid and a higher alcohol. And providing a surface protective film characterized in that the acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer and has the following properties (1) and (2).
(1) After the surface of the acrylic pressure-sensitive adhesive layer of the surface protective film is attached to the surface of the adherend X below at a temperature of 23 ° C. and a humidity of 30%, the temperature is 50 ° C., the pressure is 5 atm, and the time is 15 minutes. The water contact angle A on the surface of the adherend X is 70 ° or less after the surface protective film is peeled off after being allowed to adhere in an autoclave under conditions and left at a temperature of 23 ° C. and a humidity of 30% for 12 hours. (2) After the surface of the above-mentioned acrylic pressure-sensitive adhesive layer of the surface protective film was attached to the surface of the following adherend X at a temperature of 23 ° C. and a humidity of 30%, it was autoclaved at a temperature of 50 ° C., a pressure of 5 atm, and a time of 15 minutes. Acrylic tape (manufactured by Nitto Denko Corp., product number No. 31B, substrate thickness) on the surface of the adherend X after being adhered and left at a temperature of 23 ° C. and a humidity of 30% for 12 hours and peeling off the surface protective film. 25 μm) adhesive strength (peeling Separation angle 180 °, pulling speed 300 mm / min) is the adhesive force (peeling angle 180 °, pulling speed 300 mm) of acrylic tape (Nitto Denko Corporation, product number No. 31B, substrate thickness 25 μm) on the following adherend X surface. Adherent X higher than (min./min): hard coat film having a water contact angle of 80 to 100 °

  The substrate is preferably a polyethylene terephthalate film or a polyethylene naphthalate film.

  The topcoat layer preferably further contains an antistatic component.

  The acrylic pressure-sensitive adhesive layer preferably contains an anionic surfactant.

  The content of the anionic surfactant is preferably 0.2 to 4 parts by weight with respect to 100 parts by weight of the acrylic polymer.

  The surface protective film is preferably a surface protective film for an optical member.

  Moreover, this invention provides the optical member containing the said surface protection film.

  Since the surface protective film of the present invention has the above-described configuration, it has excellent whitening resistance, good appearance, and after peeling off the surface protective film, the adhesion of the adherend surface to other laminated members such as interlayer fillers. Can be prevented from being damaged.

It is a schematic sectional drawing which shows an example of the usage pattern of a surface protection film. It is a schematic sectional drawing which shows an example of the form before use of a surface protection film. It is a schematic sectional drawing which shows an example of the peeling method of a surface protection film. It is explanatory drawing which shows the measuring method of back surface peeling strength.

[Surface protection film]
The surface protective film of the present invention is provided on a substrate having a first surface and a second surface, a topcoat layer provided on the first surface side of the substrate, and the second surface side of the substrate. It is a surface protection film provided with the made acrylic adhesive layer.

  Hereinafter, the surface protective film of the present invention will be described with an example of a preferred embodiment of the present invention. In the following drawings, members / parts having the same action are described with the same reference numerals, and redundant descriptions may be omitted or simplified. In addition, the embodiment described in the drawings is schematically illustrated for clearly explaining the present invention, and does not accurately represent the size and scale of the surface protective film of the present invention actually provided as a product. .

  In the present specification, the “slip agent” refers to a component that can exert an effect of improving the slipperiness of the topcoat layer by being contained in the topcoat layer. The improvement in the slipperiness of the topcoat can be grasped, for example, by the decrease in the friction coefficient of the topcoat layer. The “binder” in the topcoat layer refers to a basic component that contributes to the formation of the topcoat layer. The “polyester resin” refers to a resin containing polyester (referred to as a polymer having a main chain formed by an ester bond between monomers) as a main component (preferably a component containing more than 50% by weight). . The “acrylic pressure-sensitive adhesive composition” is a composition for forming an acrylic pressure-sensitive adhesive layer, wherein an acrylic polymer is a base polymer (the main component of the polymer components contained in the acrylic pressure-sensitive adhesive composition). Component, preferably a component containing more than 50% by weight). “Acrylic polymer” means a monomer having at least one (meth) acryloyl group in one molecule (hereinafter sometimes referred to as “acrylic monomer”) as a main constituent monomer component (of the monomer). The main component, preferably a polymer comprising 50% by weight or more of the total amount of monomers constituting the acrylic polymer. The above “(meth) acryloyl group” means an acryloyl group and a methacryloyl group comprehensively. Similarly, “(meth) acrylate” is a generic term for acrylate and methacrylate. In the present specification, the “alkylene oxide chain” means a portion in which two or more oxyalkylene units (—OR—) and oxyalkylene units are continuous (that is, a structural portion represented by — (OR) n—, where n ≧ 2, which can also be understood as a polyalkylene oxide chain.

<Configuration and usage of surface protective film>
An example of the structure of the surface protective film of the present invention and an example of its usage are shown in FIG. The surface protective film 1 is provided on the base 12 having the first surface 12A and the second surface 12B, the topcoat layer 14 provided on the first surface (back surface) 12A, and the second surface (front surface) 12B. And an acrylic pressure-sensitive adhesive layer 20. The substrate 12 is preferably a transparent resin film (for example, a polyester resin film). Moreover, as shown in FIG. 1, it is preferable that the topcoat layer 14 is provided directly (without interposing another layer) on the first surface 12A. The acrylic pressure-sensitive adhesive layer 20 is preferably formed continuously (on the entire surface of the second surface 12B), but is not limited to such a form. For example, the acrylic pressure-sensitive adhesive layer 20 is regular or random such as a dot shape or a stripe shape. It may be formed in a simple pattern. The surface protective film 1 has a surface (adhesive surface, that is, a surface to be adhered to an adherend) 20 </ b> A of an acrylic pressure-sensitive adhesive layer 20 attached to the surface of an adherend (an optical component such as a polarizing plate) 50. Used. The surface protective film 1 before use (that is, before application to the adherend) is preferably in a form in which the surface 20A of the acrylic pressure-sensitive adhesive layer 20 is protected by a release liner 30 as shown in FIG. May be. The release liner 30 has a release surface at least the surface facing the acrylic pressure-sensitive adhesive layer 20.

  The surface protective film 1 that has become unnecessary after the role of protecting the adherend 50 is peeled off from the surface of the adherend 50 and removed. The operation of removing the surface protective film 1 from the surface of the adherend 50 is performed by, for example, attaching an adhesive tape (pickup tape) 60 to the back surface 1A of the surface protective film 1 (the surface of the top coat layer 14) as shown in FIG. And an operation including an operation of lifting at least a part (preferably at least a part of the outer edge) of the surface protective film 1 together with the adhesive tape 60 from the surface of the adherend 50. Thus, by pulling the pickup tape 60 attached to the back surface 1A of the surface protection film 1, the surface protection film 1 is peeled off from the adherend 50 using the adhesive force of the pickup tape 60 to the back surface 1A. You can get an introduction. According to this aspect, the operation of removing the surface protective film 1 from the adherend 50 can be performed efficiently. For example, the pickup tape 60 is attached to the back surface 1 </ b> A of the surface protection film 1 so that one end thereof protrudes from the outer edge of the surface protection film 1, as indicated by a virtual line in FIG. 3. Then, as shown by a solid line in FIG. 3, it is preferable to grip the one end of the pickup tape 60 and pull the surface protection film 1 so as to be folded back (turned) from its outer edge. In addition, after the outer edge of the surface protective film 1 is peeled off from the adherend 50 as shown in FIG. 3, the operation of peeling the remaining portion of the surface protective film 1 from the adherend 50 continues to pull the pickup tape 60. Or may be performed by directly grasping and pulling a portion of the surface protective film 1 that has already been peeled off from the adherend 50.

<Base material>
Although the said base material in the surface protection film of this invention is not specifically limited, For example, a resin film is preferable. The resin film is preferably formed by molding various resin materials into a film shape. As said resin material, what can comprise the resin film excellent in the characteristic of 1 or 2 or more among transparency, mechanical strength, thermal stability, moisture shielding property, isotropic property, etc. is preferable. For example, polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate; celluloses such as diacetyl cellulose and triacetyl cellulose; polycarbonates; resins such as acrylic polymers such as polymethyl methacrylate Preferable is a transparent (meaning including colored transparent) resin film composed of a resin material having a main component (for example, a component contained in an amount of more than 50% by weight based on the total amount of the resin material). Examples of other resins constituting the resin film include styrenes such as polystyrene and acrylonitrile-styrene copolymer; polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, and ethylene-propylene copolymer. Examples include olefins; polyvinyl chlorides; nylon 6, nylon 6, 6, polyamides such as aromatic polyamide, and the like as main components. Alternatively, polyimides, polysulfones, polyether sulfones, polyether ether ketones, polyphenylene sulfides, polyvinyl alcohols, polyvinylidene chloride, polyvinyl butyrals, polyarylates, polyoxymethylenes, epoxies, etc. A resin material as a component can be mentioned. Among these, the base material is preferably a polyethylene terephthalate film or a polyethylene naphthalate film from the viewpoint of high transparency and anisotropy of optical properties (such as retardation). In addition, the resin material which comprises the said resin film can be used individually or in combination of 2 or more types. In addition, the said resin material may be comprised only from resin mentioned above.

  The resin film for the substrate is preferably one having transparency and little anisotropy in optical characteristics (such as retardation). In particular, it is preferable that the resin film used for the base material of the surface protective film for optical components has little optical anisotropy of the resin film. The resin film may have a single layer structure or a structure in which a plurality of layers having different compositions are laminated. Among these, a resin film having a single layer structure is preferable.

  Although the refractive index of the said resin film is not specifically limited, From a viewpoint of an external appearance characteristic, it is preferable to exist in the range of 1.43-1.6, More preferably, it is the range of 1.45-1.5. A manufacturer's notarized value can be adopted as the value of the refractive index. When there is no notarized value, a value measured by the JIS K 7142 A method can be adopted. The total light transmittance in the visible light wavelength region of the resin film is not particularly limited, but is preferably 70% or more (for example, 70 to 99%), more preferably 80% or more from the viewpoint of transparency. (For example, 80 to 99%), more preferably 85% or more (for example, 85 to 99%). The manufacturer's notarized value can be adopted as the value of the total light transmittance. When there is no notarized value, a value measured in accordance with JIS K 7361-1 can be adopted.

  The substrate is a resin film (polyester resin film) in which a resin (polyester resin) containing polyester as a main component (for example, a component containing more than 50% by weight with respect to the total amount of the resin material) is formed into a film shape. It is preferable. In particular, a resin film (PET film) in which the polyester is mainly PET and a resin film (PEN film) in which the polyester is mainly PEN are preferable.

  Various additives such as an antioxidant, an ultraviolet absorber, an antistatic component, a plasticizer, and a colorant (pigment, dye, etc.) may be blended in the resin material constituting the substrate as necessary. Good. For example, corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of a primer are applied to the first surface of the substrate (the back surface, that is, the surface on which the topcoat layer is provided). Or the usual surface treatment may be given. Such a surface treatment is preferably, for example, a treatment for improving the adhesion between the back surface of the substrate and the topcoat layer. Furthermore, a surface treatment in which a polar group such as a hydroxyl group (—OH group) is introduced on the back surface of the substrate is also preferable. In addition, in the surface protective film of the present invention, the second surface of the base material (front surface, that is, the surface on the side where the acrylic pressure-sensitive adhesive layer is formed) is listed as a surface treatment applied to the first surface of the base material. A surface treatment selected from the surface treatments described above may be applied. Such a surface treatment is preferably a treatment for improving the adhesion between the substrate (support) and the acrylic pressure-sensitive adhesive layer (the anchoring property of the pressure-sensitive adhesive layer).

  Moreover, the thickness of the said base material can be suitably selected in consideration of the use, purpose, usage pattern, etc. of the surface protective film. The thickness of the base material is preferably 10 to 200 μm, more preferably 15 to 100 μm, and still more preferably 20 to 20 m in consideration of workability such as strength and handleability and ease of cost and appearance inspection. 70 μm.

<Binder>
The surface protective film of the present invention has a topcoat layer on the first surface (back surface) side of the substrate. Especially, it is preferable to have a topcoat layer on the first surface of the substrate. The top coat layer contains at least a wax as a slip agent and a polyester resin as a binder. The polyester resin is a resin material containing polyester as a main component (preferably a component occupying 50% by weight or more, more preferably 75% by weight or more, and still more preferably 90% by weight or more). The polyester is selected from polyvalent carboxylic acids (preferably dicarboxylic acids) having two or more carboxyl groups in one molecule and derivatives thereof (an anhydride, esterified product, halide, etc. of the polyvalent carboxylic acid). One or more compounds selected from one or more compounds (polyhydric carboxylic acid component) and polyhydric alcohols (preferably diols) having two or more hydroxyl groups in one molecule (Polyhydric alcohol component) has a condensed structure.

  The compound corresponding to the polyvalent carboxylic acid component is not particularly limited. For example, oxalic acid, malonic acid, difluoromalonic acid, alkylmalonic acid, succinic acid, tetrafluorosuccinic acid, alkylsuccinic acid, (±) -apple Acid, meso-tartaric acid, itaconic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, acetylenedicarboxylic acid, glutaric acid, hexafluoroglutaric acid, methylglutaric acid, glutaconic acid, adipic acid, dithioadipic acid, methyladipine Acid, dimethyladipic acid, tetramethyladipic acid, methyleneadipic acid, muconic acid, galactaric acid, pimelic acid, suberic acid, perfluorosuberic acid, 3,3,6,6-tetramethylsuberic acid, azelaic acid, sebacic acid , Perfluoro sebacic acid, brassic acid, de Aliphatic dicarboxylic acids such as sildicarboxylic acid, tridecyldicarboxylic acid, and tetradecyldicarboxylic acid; cycloalkyldicarboxylic acid (for example, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid), 1,4- (2 -Norbornene) dicarboxylic acid, 5-norbornene-2,3-dicarboxylic acid (hymic acid), alicyclic dicarboxylic acids such as adamantane dicarboxylic acid, spiroheptane dicarboxylic acid; phthalic acid, isophthalic acid, dithioisophthalic acid, methylisophthalic acid , Dimethylisophthalic acid, chloroisophthalic acid, dichloroisophthalic acid, terephthalic acid, methyl terephthalic acid, dimethyl terephthalic acid, chloroterephthalic acid, bromoterephthalic acid, naphthalenedicarboxylic acid, oxofluorenedicarboxylic acid, ant Rasendicarboxylic acid, biphenyldicarboxylic acid, biphenylenedicarboxylic acid, dimethylbiphenylenedicarboxylic acid, 4,4 "-p-terephenylenedicarboxylic acid, 4,4" -p-quarelphenyldicarboxylic acid, bibenzyldicarboxylic acid, azobenzenedicarboxylic acid , Homophthalic acid, phenylenediacetic acid, phenylenedipropionic acid, naphthalenedicarboxylic acid, naphthalenedipropionic acid, biphenyldiacetic acid, biphenyldipropionic acid, 3,3 ′-[4,4 ′-(methylenedi-p-biphenylene) di Aromatic dicarboxylic acids such as propionic acid, 4,4′-bibenzyldiacetic acid, 3,3 ′ (4,4′-bibenzyl) dipropionic acid, oxydi-p-phenylenediacetic acid; Products; esters of the above polyvalent carboxylic acids (eg alkyl Esters, monoesters, diesters and the like may be used. ); Acid halides corresponding to the polyvalent carboxylic acid (for example, dicarboxylic acid chloride) and the like.

  Among them, the compounds corresponding to the polyvalent carboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and acid anhydrides thereof; adipic acid, sebacic acid, azelaic acid, succinic acid, fumaric acid, Aliphatic dicarboxylic acids such as maleic acid and acid anhydrides thereof; alicyclic carboxylic acids such as highmic acid and 1,4-cyclohexanedicarboxylic acid and acid anhydrides thereof; and lower alkyl esters of the above dicarboxylic acids (eg, carbon An ester with a monoalcohol having 1 to 3 atoms is preferred.

  On the other hand, the compound corresponding to the polyhydric alcohol component is not particularly limited, but ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butane. Diol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methylpentanediol, diethylene glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 2-methyl Diols such as 1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, xylylene glycol, hydrogenated bisphenol A, and bisphenol A Kind. In addition, alkylene oxide adducts of these compounds (for example, ethylene oxide adducts, propylene oxide adducts, etc.) can be mentioned.

  In particular, the polyester resin preferably contains a water-dispersible polyester. That is, it is preferable to contain water-dispersible polyester as a main component. Such water-dispersible polyester has, for example, a hydrophilic functional group (for example, one or more of hydrophilic functional groups such as a sulfonic acid metal base, a carboxyl group, an ether group, and a phosphoric acid group) in the polymer. Examples thereof include polyesters having improved water dispersibility by introduction. As a method for introducing a hydrophilic functional group into a polymer, a method of copolymerizing a compound having a hydrophilic functional group, a polyester or a precursor thereof (for example, a polyvalent carboxylic acid component, a polyhydric alcohol component, an oligomer thereof, etc.) ) May be modified to produce a hydrophilic functional group. Preferred water-dispersible polyesters include polyesters (copolyesters) obtained by copolymerizing a compound having a hydrophilic functional group.

In the surface protective film of the present invention, the polyester resin used as the binder of the topcoat layer is not particularly limited, but may be a saturated polyester or a unsaturated polyester as a main component. May be. Especially, as for the polyester resin used as a binder of a topcoat layer, what the main component of the said polyester resin is saturated polyester is preferable. In particular, a polyester resin mainly composed of a saturated polyester (for example, a saturated copolymerized polyester) imparted with water dispersibility is more preferable.
Such a polyester resin (including those prepared in the form of an aqueous dispersion) can be synthesized by a known method, or a commercially available product can be easily obtained.

The molecular weight of the polyester resin is not particularly limited, the weight-average molecular weight in terms of standard polystyrene measured by gel permeation chromatography (GPC) as ^{(Mw), 0.5 × 10 4} ~15 × 10 4 ( preferably 1 × 10 ^{4 to} 6 × 10 ⁴ ) are preferable. Moreover, the glass transition temperature (Tg) of the said polyester resin is although it does not specifically limit, 0-100 degreeC is preferable, More preferably, it is 10-80 degreeC.

  The topcoat layer is a resin other than a polyester resin (for example, an acrylic resin) as a binder within a range that does not impair the performance (for example, performance such as transparency, scratch resistance, and whitening resistance) of the surface protective film of the present invention. , An acrylic-urethane resin, an acrylic-styrene resin, an acrylic-silicone resin, a silicone resin, a polysilazane resin, a polyurethane resin, a fluororesin, a polyolefin resin, or the like). Also good. In particular, in the surface protective film of the present invention, it is preferable that the binder of the topcoat layer is substantially composed of only a polyester resin. For example, a top coat layer in which the proportion of the polyester resin in the binder is 98 to 100% by weight is preferable. The proportion of the binder in the entire top coat layer is not particularly limited, but is preferably 50 to 95% by weight, and more preferably 60 to 90% by weight.

<Slip agent>
The top coat layer in the surface protective film of the present invention contains an ester of a higher fatty acid and a higher alcohol (hereinafter also referred to as “wax ester”) as a slipping agent (slipping property imparting component) (as a wax). Here, the “higher fatty acid” refers to a carboxylic acid (particularly a monovalent carboxylic acid) having 8 or more (preferably 10 or more, more preferably 10 or more and 40 or less) carbon atoms. The “higher alcohol” is an alcohol having 6 or more carbon atoms (preferably 10 or more, more preferably 10 or more and 40 or less) (particularly monovalent or divalent alcohol, more preferably monovalent alcohol). Say. A topcoat layer having a composition containing a combination of such a wax ester and the above binder (polyester resin) is not easily whitened even when kept at high temperature and high humidity. Therefore, the surface protective film of the present invention having such a top coat layer has a higher appearance quality.

In the surface protective film of the present invention, the reason why excellent whitening resistance (for example, the property of being difficult to be whitened even when kept under high temperature and high humidity conditions) is realized by the top coat layer having the above configuration is not clear, but the following reasons Is guessed. That is, it is estimated that the conventionally used silicone lubricant exhibits a function of imparting slipperiness to the surface of the topcoat layer by bleeding. However, these silicone lubricants tend to vary in the degree of bleeding due to differences in storage conditions (temperature, humidity, aging, etc.). For this reason, for example, moderate slipperiness can be obtained over a relatively long period (for example, about 3 months) immediately after the production of the surface protective film when kept under normal storage conditions (for example, 25 ° C., 50% RH). When the amount of the silicone-based lubricant used is set as described above, if this surface protective film is stored for two weeks under high temperature and high humidity conditions (for example, 60 ° C., 95% RH), the bleeding of the lubricant will proceed excessively. . Such excessively bleed silicone lubricant whitens the topcoat layer (and thus the surface protective film).
In the surface protective film of the present invention, a specific combination of a wax ester as a slip agent and a polyester resin as a binder of the topcoat layer is employed. According to the combination of the slip agent and the binder, the degree of bleeding from the top coat layer of the wax ester is not easily affected by the storage conditions. It is considered that the whitening resistance of the surface protective film was improved by this.

The wax ester is not particularly limited, but is preferably a compound represented by the following general formula (W). Moreover, the said wax ester may contain 1 type of compounds shown by the following general formula (W), and may contain 2 or more types.
X-COO-Y (W)
Here, X and Y in the formula (W) are each independently a hydrocarbon group having 10 to 40 carbon atoms (preferably 10 to 35, more preferably 14 to 35, still more preferably 20 to 32). It is. If the number of carbon atoms is too small, the effect of imparting slipperiness to the topcoat layer tends to be insufficient. The hydrocarbon group may be saturated or unsaturated, but is preferably a saturated hydrocarbon group. Further, the hydrocarbon group may have a structure containing an aromatic ring or a structure not containing such an aromatic ring (aliphatic hydrocarbon group). Further, it may be a hydrocarbon group (alicyclic hydrocarbon group) having a structure containing an aliphatic ring, and is a chain-like hydrocarbon group (meaning to include a straight chain or branched chain). It may be.

The wax ester is preferably a compound in which X and Y in the formula (W) are each independently a chain alkyl group having 10 to 40 carbon atoms (more preferably a linear alkyl group). Specific examples of such compounds include myricyl cellotate (CH ₃ (CH ₂ ) ₂₄ COO (CH ₂ ) ₂₉ CH ₃ ), myricyl palmitate (CH ₃ (CH ₂ ) ₁₄ COO (CH ₂ ) ₂₉ CH ₃ ), Examples thereof include cetyl palmitate (CH ₃ (CH ₂ ) ₁₄ COO (CH ₂ ) ₁₅ CH ₃ ), stearyl stearyl (CH ₃ (CH ₂ ) ₁₆ COO (CH ₂ ) ₁₇ CH ₃ ), and the like.

  The melting point of the wax ester is not particularly limited, but is preferably 50 ° C. or higher, more preferably 60 ° C. or higher, still more preferably 70 ° C. or higher, and particularly preferably 75 ° C. or higher. According to such a wax ester, higher whitening resistance can be obtained. The wax ester preferably has a melting point of 100 ° C. or lower. Since such a wax ester has a high effect of imparting slipperiness, it is possible to form a topcoat layer having higher scratch resistance. It is preferable for the wax ester to have a melting point of 100 ° C. or lower because an aqueous dispersion of the wax ester can be easily prepared. For example, myrisyl cellotate is preferably mentioned.

  Although it does not specifically limit as a raw material of the said topcoat layer, The natural wax containing the said wax ester is mentioned. As such a natural wax, the content ratio of the above wax ester (the total of the content ratios when two or more wax esters are included) is 50% by weight or more (preferably 65% by weight) based on the nonvolatile content (NV). Above, more preferably 75% by weight or more) is preferable. For example, carnauba wax (for example, containing 60% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more of myricyl cellotate), plant wax such as palm wax; beeswax, whale wax Natural waxes such as animal waxes can be used. The melting point of the natural wax to be used is not particularly limited, but is preferably 50 ° C. or higher (more preferably 60 ° C. or higher, further preferably 70 ° C. or higher, particularly preferably 75 ° C. or higher). The raw material of the top coat layer may be a chemically synthesized wax ester, or may be a product obtained by purifying natural wax to increase the purity of the wax ester. These raw materials can be used alone or in combination of two or more.

  The ratio of the slip agent in the entire top coat layer is not particularly limited, but is preferably 5 to 50% by weight, and more preferably 10 to 40% by weight. When the content of the slip agent is 5% by weight or more, good scratch resistance is easily obtained, which is preferable. Moreover, when the content rate of a slip agent is 50 weight% or less, it becomes easy to acquire the improvement effect of whitening resistance, and it is preferable.

  In the surface protective film of the present invention, the top coat layer may contain other slip agent in addition to the wax ester as long as the effect is not impaired. Such other slip agents are not particularly limited, but include, for example, petroleum waxes (paraffin wax, etc.), mineral waxes (montan wax, etc.), higher fatty acids (serotic acid, etc.), neutral fats (palmitic acid triglycerides) Etc.). Furthermore, in addition to the wax ester, the top coat layer may additionally contain a general silicone lubricant, a fluorine lubricant and the like. The surface protective film of the present invention does not substantially contain such a silicone-based lubricant, fluorine-based lubricant, etc. (the total content thereof is 0.01% by weight or less of the entire topcoat layer, or less than the detection limit). It is preferable. In addition, the inclusion of a silicone compound used for a purpose other than the lubricant (for example, as an antifoaming agent for a coating agent for forming a top coat described later) is not excluded.

  The topcoat layer in the surface protective film of the present invention is optionally provided with an antistatic component, a crosslinking agent, an antioxidant, a colorant (pigment, dye, etc.), and a fluidity modifier (thixotropic agent, thickener, etc.). Further, it may contain additives such as film-forming aids, surfactants (antifoaming agents, dispersants, etc.) and preservatives.

<Antistatic component of topcoat layer>
In the surface protective film of the present invention, the top coat layer preferably contains an antistatic component in addition to a wax as a slipping agent and a polyester resin as a binder. When the surface protective film of the present invention is excellent in antistatic properties, it can be preferably used in, for example, processing or transporting an article that dislikes static electricity such as a liquid crystal cell or a semiconductor device.
When the antistatic component is contained in the topcoat layer, both the scratch resistance and the antistatic property can be imparted to the surface protective film. Therefore, unlike a configuration in which a unique layer (antistatic layer) is provided for antistatic (for example, a configuration in which an antistatic layer is disposed between the back surface of the substrate and the topcoat layer), the surface protective film It is possible to impart antistatic properties to the surface protective film or increase the antistatic properties without increasing the number of layers constituting the layer. This is advantageous from the viewpoint of improving the visibility of the adherend surface when the appearance inspection of the adherend is performed through the surface protective film. Moreover, it is preferable also from a viewpoint of productivity of a surface protection film.

  The antistatic component is a component capable of exhibiting an action of preventing or suppressing the charge of the surface protective film. When the topcoat layer contains an antistatic component, the antistatic component is not particularly limited. For example, an organic or inorganic conductive material (organic conductive material, inorganic conductive material), various antistatic agents Etc. The antistatic components can be used alone or in combination of two or more.

  The organic conductive material is not particularly limited, but is a cationic antistatic agent having a cationic functional group such as a quaternary ammonium salt, a pyridinium salt, a primary amino group, a secondary amino group, or a tertiary amino group; Anionic antistatic agents with anionic functional groups such as acid salts, sulfates, phosphonates, phosphates; amphoteric ion charges such as alkylbetaines and their derivatives, imidazolines and their derivatives, alanine and their derivatives Inhibitors; Nonionic antistatic agents such as amino alcohol and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof; cation-type, anion-type, and zwitterionic-type ion conductive groups (for example, quaternary ammonium bases) Obtained by polymerizing or copolymerizing monomers having Conductive polymers; polythiophene, polyaniline, polypyrrole, polyethylene imine, a conductive polymer such as an allylamine-based polymer. The said organic electroconductive substance can be used individually or in combination of 2 or more types.

  The inorganic conductive material is not particularly limited, but is tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium. , Titanium, iron, cobalt, copper iodide, ITO (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), and the like. In addition, such an inorganic electroconductive substance can be used individually or in combination of 2 or more types.

  The antistatic agent is not particularly limited, and examples thereof include a cationic antistatic agent, an anionic antistatic agent, an amphoteric ion antistatic agent, a nonionic antistatic agent, and the cationic, anionic and zwitterionic types. An ion conductive polymer obtained by polymerization or copolymerization of a monomer having an ion conductive group may be used.

  In the surface protective film of the present invention, the antistatic component used for the topcoat layer preferably contains an organic conductive substance. Although it does not specifically limit as said organic electroconductive substance, Various conductive polymers are mentioned preferably from the point of coexistence with favorable antistatic property and high scratch resistance. Although it does not specifically limit as a conductive polymer, A polythiophene, polyaniline, a polypyrrole, a polyethyleneimine, an allylamine type polymer etc. are mentioned preferably. Such a conductive polymer can be used individually or in combination of 2 or more types. In addition, the organic conductive material such as the conductive polymer may be used in combination with other antistatic components (inorganic conductive material, antistatic agent, etc.). Although the usage-amount of the said conductive polymer is not specifically limited, It is preferable that it is 10-200 weight part with respect to 100 weight part of binder contained in a topcoat layer, More preferably, it is 25-150 weight part, More preferably Is 40 to 120 parts by weight. When the amount of the conductive polymer used is 10 parts by weight or more, a good antistatic effect is easily obtained, which is preferable. Moreover, when it is 150 parts by weight or less, the compatibility of the conductive polymer in the topcoat layer is sufficiently obtained, and it becomes easy to obtain good appearance quality and good solvent resistance of the topcoat layer.

In the surface protective film of the present invention, preferred conductive polymers include polythiophene and polyaniline. The polythiophene preferably has a polystyrene-equivalent weight average molecular weight (hereinafter referred to as “Mw”) of 40 × 10 ⁴ or less (more preferably 30 × 10 ⁴ or less). Moreover, as polyaniline, that whose Mw is 50 * 10 < ⁴ > or less (more preferably 30 * 10 < ⁴ > or less) is preferable. Further, the Mw of these conductive polymers is preferably 0.1 × 10 ⁴ or more (more preferably 0.5 × 10 ⁴ or more). In the present specification, polythiophene refers to a polymer of unsubstituted or substituted thiophene. In particular, the substituted thiophene polymer is preferably poly (3,4-ethylenedioxythiophene).

As a method of forming the topcoat layer, when a method of applying a coating agent for forming a topcoat layer to a substrate and drying or curing is employed, the conductive polymer used for the preparation of the coating agent is the conductive layer. A polymer in which the polymer is dissolved or dispersed in water (conductive polymer aqueous solution) is preferable. Such a conductive polymer aqueous solution is obtained by, for example, dissolving or dispersing a conductive polymer having a hydrophilic functional group (synthesized by a method such as copolymerizing a monomer having a hydrophilic functional group in the molecule) in water. It is prepared by. Examples of the hydrophilic functional group include sulfo group, amino group, amide group, imino group, hydroxyl group, mercapto group, hydrazino group, carboxyl group, quaternary ammonium group, sulfate group (—O—SO ₃ H), phosphorus An acid ester group (for example, —O—PO (OH) ₂ ) and the like can be mentioned. Such hydrophilic functional groups may form a salt. As a commercial item of polythiophene aqueous solution, the brand name “Denatron” series manufactured by Nagase Chemtech Co., Ltd. may be mentioned. Moreover, as a commercial item of polyaniline sulfonic acid aqueous solution, the brand name "aqua-PASS" by Mitsubishi Rayon Co., Ltd. is mentioned.

In the surface protective film of the present invention, it is preferable to use an aqueous polythiophene solution for the preparation of the coating agent, and an aqueous polythiophene solution containing polystyrene sulfonate (PSS) (a form in which PSS is added as a dopant to polythiophene). Is more preferable. Such an aqueous solution may contain polythiophene: PSS at a mass ratio of 1: 1 to 1:10. The total content of polythiophene and PSS in the aqueous solution is not particularly limited, but is preferably 1 to 5% by weight. Examples of such commercially available polythiophene aqueous solutions include H.P. C. The trade name “Baytron” from Stark may be mentioned.
In addition, when using the polythiophene aqueous solution containing PSS as described above, the total amount of polythiophene and PSS is not particularly limited, but is preferably 5 to 200 parts by weight with respect to 100 parts by weight of the binder. Preferably it is 10-100 weight part, More preferably, it is 25-70 weight part.

  If necessary, the topcoat layer is composed of a conductive polymer and one or more other antistatic components (an organic conductive material other than the conductive polymer, an inorganic conductive material, an antistatic agent, etc.) May be included together. In the surface protective film of the present invention, it is particularly preferable that the topcoat layer contains substantially no antistatic component other than the conductive polymer. That is, it is particularly preferable that the antistatic component contained in the topcoat layer is substantially only a conductive polymer.

<Crosslinking agent>
In the surface protective film of the present invention, the topcoat layer preferably contains a crosslinking agent. Such a crosslinking agent is not particularly limited, and examples thereof include a melamine crosslinking agent, an isocyanate crosslinking agent, and an epoxy crosslinking agent. In addition, a crosslinking agent can be used individually or in combination of 2 or more types. According to such a crosslinking agent, at least one of the following effects can be obtained: improved scratch resistance, improved solvent resistance, improved print adhesion, and reduced friction coefficient (that is, improved slipperiness). Especially, it is preferable that the said crosslinking agent is a melamine type crosslinking agent. Further, the top coat layer may be a layer containing substantially only a melamine-based crosslinking agent as a crosslinking agent, that is, a layer containing substantially no crosslinking agent other than the melamine-based crosslinking agent.

<Formation of topcoat layer>
The method for forming the top coat layer is not particularly limited. The top coat layer is based on a liquid composition (coating composition for forming a top coat layer) in which the binder, the slip agent, and an additive added as necessary are dispersed or dissolved in an appropriate solvent. It is preferably formed by a technique including coating. For example, as a method for forming the topcoat layer, a method of applying the coating composition to the first surface of the substrate and drying it, and performing a curing treatment (heat treatment, ultraviolet treatment, etc.) as necessary is preferably exemplified. . NV of the coating composition is not particularly limited, but is preferably 5% by weight or less (for example, 0.05 to 5% by weight), more preferably 1% by weight or less (for example, 0.10 to 1% by weight). It is. When forming a thin topcoat layer, the NV of the coating composition is preferably 0.05 to 0.50% by weight (particularly 0.10 to 0.30% by weight). Thus, a more uniform topcoat layer is formed by using a coating composition having a low NV.

  As the solvent constituting the coating composition for forming the topcoat layer, a solvent capable of stably dissolving or dispersing the topcoat layer forming component is preferable. Such a solvent may be an organic solvent, water, or a mixed solvent thereof. Examples of the organic solvent include esters such as ethyl acetate; ketones such as methyl ethyl ketone, acetone and cyclohexanone; cyclic ethers such as tetrahydrofuran (THF) and dioxane; aliphatic or alicyclic such as n-hexane and cyclohexane. Hydrocarbons; aromatic hydrocarbons such as toluene and xylene; aliphatic or alicyclic alcohols such as methanol, ethanol, n-propanol, isopropanol, and cyclohexanol; alkylene glycol monoalkyl ether (for example, ethylene glycol monomethyl ether) , Ethylene glycol monoethyl ether, and the like) and glycol ethers such as dialkylene glycol monoalkyl ether. Moreover, the said organic solvent can be used individually or in combination of 2 or more types. Especially, as a solvent which comprises the said coating composition for topcoat layer formation, the mixed solvent (For example, the mixed solvent of water and ethanol) which has water as a main component is mentioned preferably.

<Properties of top coat layer>
Although the thickness of the topcoat layer in the surface protection film of this invention is not specifically limited, Preferably it is 3-500 nm, More preferably, it is 4-100 nm, More preferably, it is 5-60 nm. When the thickness of the top coat layer is 500 nm or less, good transparency (light transmittance) is easily obtained in the surface protective film, which is preferable. Moreover, when it is 3 nm or more, it becomes easy to form a topcoat layer uniformly (for example, in the thickness of the topcoat layer, the variation in thickness depending on the location becomes small), and thus the appearance of the surface protective film is improved. Unevenness is less likely to occur, which is preferable.

  In particular, in the surface protective film of the present invention, the thickness of the topcoat layer is not particularly limited, but is preferably 3 nm or more and less than 50 nm, more preferably 3 nm or more, from the viewpoint of obtaining a film with better appearance quality. It is less than 30 nm, more preferably 4 nm or more and less than 20 nm, and most preferably 5 nm or more and less than 11 nm. When the appearance quality of the surface protective film is excellent, the appearance inspection of the product (adhered body) can be performed with higher accuracy through the surface protective film. A small thickness of the top coat layer is also preferable from the viewpoint of little influence on the properties (optical properties, dimensional stability, etc.) of the substrate.

The thickness of the topcoat layer can be grasped by observing a cross section of the topcoat layer with a transmission electron microscope (TEM). For example, for a target sample (a substrate on which a topcoat layer is formed, a surface protective film provided with the substrate, etc.), a heavy metal dyeing treatment is performed for the purpose of clarifying the topcoat layer, followed by resin embedding. This can be grasped by performing TEM observation of the cross section of the sample by the ultrathin section method. Examples of the TEM include Hitachi TEM and model “H-7650”. In the examples described later, the binarization processing is performed on the cross-sectional image obtained under the conditions of acceleration voltage: 100 kV and magnification: 60,000 times, and then the cross-sectional area of the top coat is divided by the sample length in the field of view. Thus, the thickness of the top coat layer (average thickness in the field of view) was measured.
If the top coat layer can be observed sufficiently clearly without heavy metal staining, the heavy metal staining treatment may be omitted. Alternatively, the calibration is carried out with respect to the correlation between the thickness grasped by the TEM and the detection results by various thickness detectors (for example, a surface roughness meter, an interference thickness meter, an infrared spectrometer, various X-ray diffractometers, etc.). The thickness of the topcoat layer may be obtained by creating a line and performing the calculation.

In the surface protective film of the present invention, the surface resistivity on the surface of the topcoat layer is not particularly limited, but is preferably 10 ¹² Ω or less, more preferably 10 ⁶ Ω to 10 ¹² Ω. Such a surface protective film exhibiting surface resistivity is preferably used as a surface protective film used in, for example, processing or transporting an article that dislikes static electricity such as a liquid crystal cell or a semiconductor device. In particular, a surface protective film having a surface resistivity of 10 ¹¹ Ω or less (preferably 5 × 10 ⁶ to 10 ¹⁰ Ω, more preferably 10 ⁷ to 10 ⁹ Ω) is more preferable. The value of the surface resistivity can be calculated from the value of the surface resistance measured under an atmosphere of 23 ° C. and 50% RH using a commercially available insulation resistance measuring device.

  In the surface protective film of the present invention, the friction coefficient of the top coat layer is not particularly limited, but is preferably 0.4 or less. According to such a topcoat layer having a low coefficient of friction, when a load (a load causing scratches) is applied to the topcoat layer, the load is received along the surface of the topcoat layer, and the load The frictional force due to can be reduced. This makes it difficult for cohesive failure of the top coat layer (damage mode in which the top coat layer breaks inside) and interface fracture (damage mode in which the top coat layer is peeled off from the back surface of the base material). Therefore, if the coefficient of friction of the topcoat layer is reduced, an event that causes scratches on the surface protective film can be prevented better. The lower limit of the friction coefficient is not particularly limited, but considering the balance with other characteristics (appearance quality, printability, etc.), the friction coefficient should be 0.1 or more (for example, 0.1 or more and 0.4 or less). Is suitable, and is preferably 0.15 or more (for example, 0.15 or more and 0.4 or less). As the friction coefficient, for example, a value obtained by rubbing the surface of the topcoat layer with a vertical load of 40 mN in a measurement environment of 23 ° C. and 50% RH can be employed. The amount of the wax ester (slip agent) used is preferably set so that the preferable coefficient of friction is realized. For the adjustment of the friction coefficient, for example, it is also effective to increase the crosslink density of the topcoat layer by adding a crosslinking agent or adjusting film forming conditions.

The surface protective film of the present invention preferably has a property that the back surface (the surface of the topcoat layer) can be easily printed with oil-based ink (for example, using an oil-based marking pen). Such a surface protective film is obtained by indicating the identification number of the adherend to be protected in the process of carrying or transporting the adherend (for example, an optical component) performed with the surface protective film attached. It is suitable for displaying and displaying. Therefore, a surface protective film excellent in printability in addition to appearance quality is preferable. For example, it is preferable that the solvent is alcohol-based and has high printability for oil-based inks containing pigments. Moreover, it is preferable that the printed ink is difficult to be removed by rubbing or transfer (that is, excellent in print adhesion). The surface protective film of the present invention preferably has a solvent resistance that does not cause a noticeable change in appearance even if the print is wiped with alcohol (for example, ethyl alcohol) when the print is corrected or erased. The degree of the solvent resistance can be grasped by, for example, solvent resistance evaluation described later.
Since the topcoat layer in the surface protective film of the present invention contains a wax ester as a slip agent, further release treatment (for example, a silicone-based release agent, a long-chain alkyl-type release agent, etc.) is applied to the surface of the topcoat layer. A sufficient slipperiness (for example, the above-described preferable friction coefficient) can be obtained without performing the treatment of applying and drying the release treatment agent. Thus, the aspect in which the surface of the topcoat layer is not subjected to further peeling treatment can prevent whitening caused by the peeling treatment agent (for example, whitening due to storage under heating and humidification conditions). This is preferable. It is also advantageous from the viewpoint of solvent resistance.

<Acrylic adhesive layer>
The surface protective film of the present invention has an acrylic pressure-sensitive adhesive layer on the second surface (front surface) side of the substrate. Especially, it is preferable to have an acrylic adhesive layer on the second surface of the substrate.
The acrylic pressure-sensitive adhesive layer has the following property (1).
(1) After affixing the acrylic pressure-sensitive adhesive layer surface of the surface protective film of the present invention to the surface of the following adherend X at a temperature of 23 ° C. and a humidity of 30%, the temperature is 50 ° C., the pressure is 5 atm, and the time is 15 minutes. The water contact angle A on the surface of the adherend X is 70 ° or less (for example, 55 to 55 ° C.) after being stuck in an autoclave under the conditions of the above, left standing at a temperature of 23 ° C. and a humidity of 30% for 12 hours, and peeling off the surface protective film. 70 °).
Substrate X: Hard coat film having a water contact angle of 80 to 100 °

In the present specification, the surface protective film of the present invention is attached to the surface of the adherend X at a temperature of 23 ° C. and a humidity of 30%, and then autoclaved at a temperature of 50 ° C., a pressure of 5 atm, and a time of 15 minutes. The water contact angle on the surface of the adherend X after being brought into close contact and allowed to stand at a temperature of 23 ° C. and a humidity of 30% for 12 hours and peeling off the surface protective film may be referred to as “water contact angle A”.
The water contact angle can be measured by the method described in “5. Water contact angle” in (Evaluation) described later.

  The said water contact angle A is 70 degrees or less (for example, 55-70 degrees), for example, Preferably, it is 65 degrees or less (for example, 55-65 degrees). When the water contact angle A is 70 ° or less, when another layer is provided on the adherend surface after the surface protective film is peeled off, the wettability to the other layer on the adherend surface is excellent. Therefore, the repellency of the other layers (the property that the adhesive or paint is repelled and does not adhere uniformly) is reduced.

  The other layer provided on the adherend surface after the surface protective film of the present invention is peeled off from the adherend is not particularly limited. For example, model number “SVR7000 series” (manufactured by Dexerials Corporation) trade name “WORD” A layer provided by applying a liquid interlayer filler such as “ROCK HRJ-21” (manufactured by Kyoritsu Chemical Industry Co., Ltd.), a layer provided by applying an interlayer adhesive, etc., an optical transparent adhesive tape (for example, trade name “ LUCIACS CS9886U "(manufactured by Nitto Denko Corporation, etc.)) is provided. Among them, a layer made of an acrylic polymer (for example, trade name “LUCIACS CS9886U” (manufactured by Nitto Denko Corporation), etc.) is preferable from the viewpoint that reflection is prevented and reflection hardly occurs.

The acrylic pressure-sensitive adhesive layer further has the following property (2).
(2) After affixing the acrylic pressure-sensitive adhesive layer surface of the surface protective film of the present invention to the surface of the following adherend X at a temperature of 23 ° C. and a humidity of 30%, the temperature is 50 ° C., the pressure is 5 atm, and the time is 15 minutes. Acrylic tape (manufactured by Nitto Denko Corporation, product number No.) on the surface of the adherend X after the surface protective film of the present invention was peeled off after leaving the surface protective film of the present invention for 12 hours at 23 ° C. and 30% humidity. .31B, base material thickness 25 μm) has an adhesive strength (peeling angle 180 °, tensile speed 300 mm / min) for the following adherend X surface acrylic tape (manufactured by Nitto Denko Corporation, product number No. 31B, base material thickness 25 μm) Higher than the adhesive strength (peeling angle 180 °, tensile speed 300 mm / min).
Substrate X: Hard coat film having a water contact angle of 80 to 100 °

In this specification, the surface protective film of the present invention is attached to the surface of the adherend X at a temperature of 23 ° C. and a humidity of 30%, and then adhered by an autoclave at a temperature of 50 ° C., a pressure of 5 atm, and a time of 15 minutes. Acrylic tape (manufactured by Nitto Denko Corporation, product number No. 31B, base material thickness 25 μm) on the surface of the adherend X after leaving the surface protective film for 12 hours at a temperature of 23 ° C. and a humidity of 30%. The adhesive strength (peeling angle 180 °, tensile speed 300 mm / min) may be referred to as “adhesive strength A”. In addition, the adhesive strength of the acrylic tape (Nitto Denko Corporation, product number No. 31B, base material thickness 25 μm) to the adherend X surface (the adherend X surface not subjected to a treatment such as attaching an adhesive tape) ( The peeling angle of 180 ° and the tensile speed of 300 mm / min) may be referred to as “adhesive strength B”.
That is, the acrylic pressure-sensitive adhesive layer of the present invention has a characteristic that makes the adhesive force A higher than the adhesive force B.

  Although the said adhesive force A is not specifically limited, For example, 7.0-7.6N / 19mm is preferable, More preferably, it is 7.2-7.6N / 19mm.

  The difference between the adhesive strength A and the adhesive strength B is not particularly limited, but is preferably 0.1 N / 19 mm or more, more preferably 0.3 N / 19 mm or more, and still more preferably 0.6 N / It is 19 mm or more.

  The adhesive strength A is a 70 mm long and 19 mm wide acrylic tape piece (manufactured by Nitto Denko Corporation, product number No. 31B, base material thickness 25 μm) on the surface of the adherend X to which the surface protective film of the present invention was bonded. The pressure-sensitive adhesive surface was affixed at a temperature of 23 ° C. and a humidity of 30%, and was affixed by pressure bonding at 0.25 MPa and 300 mm / min, and left at a temperature of 23 ° C. and a humidity of 30% for 30 minutes. The measured 180 ° peel adhesive strength (temperature 23 ° C., humidity 30% RH, peel angle 180 °, tensile speed 300 mm / min) (N / 19 mm) shall be used. The adhesive force B is the same as the adhesive force A, except that an acrylic tape piece is applied to the surface of the adherend X (the surface of the adherend X not subjected to a treatment such as attaching an adhesive tape). It shall mean the 180 degree peel adhesive force measured. More specifically, it can be measured by the method described in (Evaluation) “6. Adhesive strength of acrylic tape No. 31B” described later.

  The water contact angle of the adherend X used for the measurement of the above characteristics (1) and (2) (water contact angle on the hard coat layer side surface of the hard coal film as the adherend X) is 80 to 100 °. More preferably, it is 85-90 degrees, More preferably, it is 86-88 degrees.

The acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer. That is, the acrylic pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer preferably contains an acrylic polymer as the base polymer. The acrylic polymer is a polymer containing an acrylic monomer (a monomer having a (meth) acryloyl group in the molecule) as a constituent monomer component. The above acrylic polymers can be used alone or in combination of two or more.
In the present specification, the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer may be simply referred to as “pressure-sensitive adhesive composition”.

  Although it does not specifically limit as said adhesive composition, The adhesive composition which has a base polymer as an essential component, the adhesive composition which has a monomer mixture or its partial polymer as an essential component, etc. are mentioned. Examples of the pressure-sensitive adhesive composition containing the base polymer as an essential component include so-called solvent-type pressure-sensitive adhesive compositions. Moreover, what is called an active energy ray hardening-type adhesive composition is mentioned as an adhesive composition which has a monomer mixture or its partial polymerized component as an essential component. Moreover, the said adhesive composition may contain various additives, such as surfactant, as needed. The above “monomer mixture” means a mixture of monomer components constituting the base polymer. The “monomer mixture” is a composition composed of only monomer components, and includes only one monomer component as a monomer mixture. The “partially polymerized product” means a composition in which one or more components of the monomer mixture are partially polymerized.

The acrylic polymer preferably contains a (meth) acrylic acid alkyl ester as a monomer component constituting the polymer. Examples of the (meth) acrylic acid alkyl ester include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, 6-14 carbon atoms such as isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, etc. (Meth) acrylic acid alkyl ester having the following alkyl group. Among these, (meth) acrylic acid alkyl ester having an alkyl group having 7 to 13 carbon atoms is preferable, and 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n- Nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, and n-tridecyl (meth) acrylate.
The above acrylic monomers can be used alone or in combination of two or more.

  The ratio of the (meth) acrylic acid alkyl ester to the total monomer components (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 70% by weight or more (for example, 70 to 98% by weight), for example. More preferably, it is 80 weight% or more, More preferably, it is 85 weight% or more. When the proportion of the (meth) acrylic acid alkyl ester is 85% by weight or more, the surface protective film of the present invention is easily adhered to the adherend.

The monomer component constituting the acrylic polymer preferably further contains a hydroxyl group-containing monomer. Although it does not specifically limit as said hydroxyl group containing monomer, For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate , 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol , Allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like.
The above hydroxyl group-containing monomers can be used alone or in combination of two or more.

  The ratio of the hydroxyl group-containing monomer to the total monomer component (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 0.1 to 15% by weight, and more preferably 0.5 to 13%. % By weight, more preferably 3 to 11% by weight, and particularly preferably 6 to 10% by weight. Since the proportion of the hydroxyl group-containing monomer is 0.1% by weight or more, a crosslinking point is formed and a cohesive force is obtained, so that adhesive residue is hardly generated on the adherend surface after peeling off the surface protective film of the present invention. The effect of uniform wettability and adhesiveness of the adherend surface after peeling can be obtained. When the proportion of the hydroxyl group-containing monomer is 15% by weight or less, the surface protective film of the present invention is prevented from excessively adhering to the adherend and causing heavy peeling. In particular, in the case of 6 to 10% by weight, it is possible to obtain a surface protective film capable of achieving both the peelability of the surface protective film and the adhesion between the adherend surface and another layer.

  For example, a polyfunctional monomer may be contained in the monomer component constituting the acrylic polymer from the viewpoint that a crosslinked structure can be introduced into the acrylic polymer and a necessary cohesive force can be obtained.

Although it does not specifically limit as said polyfunctional monomer, For example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6 Hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, N, N'-methylenebisacrylamide, etc. .
The said polyfunctional monomer can be used individually or in combination of 2 or more types.

  The ratio of the polyfunctional monomer to the total monomer component (100% by weight) constituting the acrylic polymer is not particularly limited, but is preferably 0.1 to 30% by weight, and more preferably 0.1 to 10% by weight. %. When the ratio of the polyfunctional monomer is 0.1% by weight or more, the flexibility and adhesiveness are excellent. When the ratio of the polyfunctional monomer is 30% by weight or less, the cohesive force does not become too high, and an appropriate adhesive strength can be obtained.

  Although the monomer component which comprises the said acrylic polymer is not specifically limited, It is preferable that the alkylene oxide group containing reactive monomer is further included.

  The average addition mole number of the oxyalkylene unit of the alkylene oxide group-containing reactive monomer is not particularly limited, but is 3 to 40 from the viewpoint of compatibility with the surfactant when a surfactant is used. More preferably, it is 4-35, More preferably, it is 5-30. When the average number of added moles is 3 or more, there is a tendency that the effect of reducing the contamination of the object to be protected by using the surfactant is efficiently obtained. Moreover, when the said average added mole number is larger than 40, since interaction with surfactant is large and there exists a tendency for the wettability improvement effect to a to-be-adhered body surface to fall, it is unpreferable. Note that the terminal of the oxyalkylene chain may be a hydroxyl group or may be substituted with another functional group.

  The alkylene oxide group-containing reactive monomer may be used alone or in combination of two or more. The content of the above-mentioned alkylene oxide group-containing reactive monomer is not particularly limited. For example, it is preferably 10% by weight or less, more preferably 7%, based on all monomer components (100% by weight) constituting the acrylic polymer. % By weight or less, more preferably 5% by weight or less, particularly preferably 3% by weight or less, particularly preferably 1% by weight or less. When the content of the alkylene oxide group-containing reactive monomer exceeds 10% by weight, the cohesive force of the pressure-sensitive adhesive composition tends to be low, which is not preferable from the viewpoint of contamination to the adherend.

  Examples of the oxyalkylene unit of the alkylene oxide group-containing reactive monomer include those having an alkylene group having 1 to 6 carbon atoms, such as an oxymethylene group, an oxyethylene group, an oxypropylene group, and an oxybutylene group. It is done. The hydrocarbon group of the oxyalkylene chain may be linear or branched.

  The alkylene oxide group-containing reactive monomer is more preferably, for example, a reactive monomer having an ethylene oxide group. By using, as a base polymer, an acrylic polymer having a reactive monomer having an ethylene oxide group as a constituent component, the compatibility between the base polymer and the surfactant is improved, bleed to the adherend is suitably suppressed, and low A fouling pressure-sensitive adhesive composition is obtained.

  Examples of the alkylene oxide group-containing reactive monomer include (meth) acrylic acid alkylene oxide adducts and reactive surfactants having reactive substituents such as acryloyl group, methacryloyl group, and allyl group in the molecule. can give.

  Specific examples of the (meth) acrylic acid alkylene oxide adduct include, for example, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meta ) Acrylate, polypropylene glycol-polybutylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, butoxy polyethylene glycol (meth) acrylate, octoxy polyethylene glycol (meth) acrylate, lauroxy polyethylene Glycol (meth) acrylate, stearoxy polyethylene glycol (Meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, octoxypolyethylene glycol - polypropylene glycol (meth) acrylate.

  Specific examples of the reactive surfactant as the alkylene oxide group-containing reactive monomer include, for example, an anionic reactive surfactant having a (meth) acryloyl group or an allyl group, and a nonionic reactive surfactant. Agents, cationic reactive surfactants and the like.

  Examples of the anionic reactive surfactant include those represented by formulas (A1) to (A10).

[R ₁ in Formula (A1) represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group or an acyl group having 1 to 30 carbon atoms, X represents an anionic hydrophilic group, R ₃ and R ₄ represent The alkylene groups having 1 to 6 carbon atoms are the same or different, and the average added mole number m and n are 0 to 40, where (m + n) represents 3 to 40. ].

[R ₁ in Formula (A2) represents hydrogen or a methyl group, R ₂ and R ₇ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and R ₃ and R ₅ are the same or different, Represents hydrogen or an alkyl group, R ₄ and R ₆ are the same or different and represent hydrogen, an alkyl group, a benzyl group or a styrene group, X represents an anionic hydrophilic group, the average number of added moles m and n are 0 to 40, where (m + n) represents a number from 3 to 40. ].

[R ₁ in Formula (A3) represents hydrogen or a methyl group, R ₂ represents an alkylene group having 1 to 6 carbon atoms, X represents an anionic hydrophilic group, and the average number of added moles n is 3 to 40 Represents a number. ].

[R ₁ in Formula (A4) represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group or an acyl group having 1 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different, and 6 represents an alkylene group, X represents an anionic hydrophilic group, the average added mole number m and n are 0 to 40, and (m + n) represents a number of 3 to 40. ].

[R ₁ in Formula (A5) represents a hydrocarbon group, an amino group, or a carboxylic acid residue, R ₂ represents an alkylene group having 1 to 6 carbon atoms, X represents an anionic hydrophilic group, and average added mole The number n represents an integer of 3 to 40. ].

[In Formula (A6), R ₁ represents a hydrocarbon group having 1 to 30 carbon atoms, R ₂ represents hydrogen or a hydrocarbon group having 1 to 30 carbon atoms, R ₃ represents hydrogen or a propenyl group, and R ₄ represents An alkylene group having 1 to 6 carbon atoms is represented, X represents an anionic hydrophilic group, and the average added mole number n represents a number of 3 to 40. ].

[R ₁ in Formula (A7) represents hydrogen or a methyl group, R ₂ and R ₄ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and R ₃ represents a hydrocarbon having 1 to 30 carbon atoms. Represents a group, M represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group, and the average number of added moles m and n is 0 to 40, where (m + n) represents a number of 3 to 40. ].

[And R ₁ and R ₅ in the formula (A8) the same or different, represent a hydrogen or a methyl group, R ₂ and R ₄ are the same or different and each represents an alkylene group having a carbon number of 1 to 6, R ₃ is C represents a hydrocarbon group having 1 to 30 carbon atoms, M represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. Represents a number. ].

[R ₁ in Formula (A9) represents an alkylene group having 1 to 6 carbon atoms, R ₂ represents a hydrocarbon group having 1 to 30 carbon atoms, and M represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. The average added mole number n represents a number of 3 to 40. ].

[R ₁ , R ₂ , and R _{3 in} Formula (A10) are the same or different and each represents hydrogen or a methyl group, and R ₄ represents a hydrocarbon group having 0 to 30 carbon atoms (in the case of 0 carbon atoms, R ₄ R ₅ and R ₆ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, X represents an anionic hydrophilic group, and the average number of added moles m and n are 0 to 40, where (m + n) represents a number from 3 to 40. ].

  X in the above formulas (A1) to (A6) and (A10) represents an anionic hydrophilic group. Examples of the anionic hydrophilic group include those represented by the following formulas (a1) to (a2).

[M ₁ in Formula (a1) represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. ].

[M ₂ and M _{3 in} Formula (a2) are the same or different and each represents hydrogen, an alkali metal, an ammonium group, or an alkanol ammonium group. ].

  Examples of the nonionic reactive surfactant include those represented by formulas (N1) to (N6).

[R ₁ in Formula (N1) represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group or an acyl group having 1 to 30 carbon atoms, and R ₃ and R ₄ may be the same or different, 6 represents an alkylene group, and average addition mole numbers m and n are 0 to 40, where (m + n) represents a number of 3 to 40. ].

[R ₁ in Formula (N2) represents hydrogen or a methyl group, R ₂ , R ₃ and R ₄ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and the average number of added moles n, m, And l represents 0 to 40, and (n + m + 1) represents a number from 3 to 40. ].

[R ₁ in Formula (N3) represents hydrogen or a methyl group, R ₂ and R ₃ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, and R ₄ is a hydrocarbon having 1 to 30 carbon atoms. A group or an acyl group, the average number of added moles m and n is 0 to 40, where (m + n) represents a number of 3 to 40. ].

[R ₁ and R _{2 in} Formula (N4) are the same or different and each represents a hydrocarbon group having 1 to 30 carbon atoms, R ₃ represents hydrogen or a propenyl group, and R ₄ represents an alkylene having 1 to 6 carbon atoms. Represents the group, and the average addition mole number n represents a number of 3 to 40. ].

[In formula (N5), R ₁ and R ₃ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms; R ₂ and R ₄ are the same or different and represent hydrogen or hydrocarbon having 1 to 30 carbon atoms; An average addition mole number m and n are 0 to 40, provided that (m + n) represents a number of 3 to 40. ].

[R ₁ , R ₂ and R _{3 in} Formula (N6) are the same or different and represent hydrogen or a methyl group, and R ₄ represents a hydrocarbon group having 0 to 30 carbon atoms (in the case of 0 carbon atoms, R ₄ R ₅ and R ₆ are the same or different and each represents an alkylene group having 1 to 6 carbon atoms, the average number of added moles m and n is 0 to 40, provided that (m + n) is 3 to 3. The number of 40 is represented. ].

  Examples of the alkylene oxide group-containing reactive monomer include, for example, Blemmer PME-400, Blemmer PME-1000, Blemmer 50POEP-800B (all of which are manufactured by NOF Corporation), Latemul PD-420, Latemul PD-430 (and above, Commercial products such as Kao Corporation, Adeka Soap ER-10, and Adeka Soap NE-10 (all of which are manufactured by Asahi Denka Kogyo Co., Ltd.) may be used.

The monomer component constituting the acrylic polymer includes monomers other than the (meth) acrylic acid alkyl ester, the hydroxyl group-containing monomer, the polyfunctional monomer, and the alkylene oxide group-containing reactive monomer (other monomers). It may be. The other monomer is not particularly limited. For example, cyano group-containing monomer, vinyl ester monomer, aromatic vinyl monomer, amide group-containing monomer, imide group-containing monomer, amino group-containing monomer, epoxy group-containing monomer, vinyl ether monomer. , N-acryloylmorpholine and the like. Among these, a cyano group-containing monomer, a vinyl ester monomer, and an aromatic vinyl monomer are preferable from the viewpoint of improving cohesion and heat resistance. Further, from the viewpoint of improving adhesive force and having a functional group that functions as a cross-linking point below, an amide group-containing monomer, an imide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, a vinyl ether monomer, and N-acryloylmorpholine are preferable. .
These other monomers can be used alone or in combination of two or more.

  Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

  Examples of the vinyl ester monomer include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate.

  Examples of the aromatic vinyl monomer include styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene, and other substituted styrene.

  Examples of the amide group-containing monomer include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethyl. Examples include methacrylamide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, diacetone acrylamide, and the like.

  Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and the like.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

  Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, and the like.

  Although the ratio of the said other monomer with respect to all the monomer components (100 weight%) which comprises the said acrylic polymer is not specifically limited, For example, it is 0 to 40 weight% (more than 0 weight% and 40 weight% or less) It is more preferably 0 to 35% by weight (more than 0% by weight and 35% by weight or less), and particularly preferably 0 to 30% by weight (more than 0% by weight to 30% by weight or less).

  The monomer component constituting the acrylic polymer includes a carboxyl group-containing monomer, a sulfo group-containing monomer, a phosphoric acid group-containing monomer, and an acid anhydride group-containing monomer from the viewpoint of suppressing an increase in adhesion to an adherend. It is preferably not included. That is, it is preferable that the other monomer does not include a carboxyl group-containing monomer, a sulfo group-containing monomer, a phosphate group-containing monomer, and an acid anhydride group-containing monomer.

  The acrylic polymer can be obtained by polymerizing the monomer component. Although it does not specifically limit as a polymerization method, For example, solution polymerization, emulsion polymerization, block polymerization, suspension polymerization, photopolymerization (active energy ray polymerization) etc. are mentioned. Among these, the solution polymerization method is preferable from the viewpoint of cost and productivity. The acrylic polymer obtained may be any of a random copolymer, a block copolymer, an alternating copolymer, a graft copolymer, and the like.

  The solution polymerization method is not particularly limited, and examples thereof include a method in which the monomer component, the polymerization initiator, etc. are dissolved in a solvent and polymerized by heating to obtain an acrylic polymer solution containing an acrylic polymer. .

Various common solvents can be used as the solvent used in the solution polymerization method. Examples of such a solvent (polymerization solvent) include aromatic hydrocarbons such as toluene, benzene and xylene; esters such as ethyl acetate and n-butyl acetate; aliphatic carbonization such as n-hexane and n-heptane. Examples of the organic solvents include hydrogens; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone.
The said solvent can be used individually or in combination of 2 or more types.

  Although the blending ratio of the solvent is not particularly limited, for example, it is preferably 10 to 1000 parts by weight, more preferably 50 to 500 parts by weight with respect to the total amount of monomer components (100 parts by weight) constituting the acrylic polymer. is there.

The polymerization initiator used in the solution polymerization method is not particularly limited, and examples thereof include a peroxide polymerization initiator and an azo polymerization initiator. The peroxide-based polymerization initiator is not particularly limited, and examples thereof include peroxycarbonate, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, and peroxyester. More specifically, benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis (t-butylperoxy)- 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclododecane and the like can be mentioned. The azo polymerization initiator is not particularly limited. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2 , 4-dimethylvaleronitrile), 2,2′-azobis (2-methylpropionic acid) dimethyl, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 1,1′-azobis ( Cyclohexane-1-carbonitrile), 2,2'-azobis (2,4,4-trimethylpentane), 4,4'-azobis-4-cyanovaleric acid, 2,2'-azobis (2-amidinopropane) Dihydrochloride, 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpro Onamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine) hydrochloride, 2,2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate Etc.
The said polymerization initiator can be used individually or in combination of 2 or more types.

  The blending ratio of the polymerization initiator is not particularly limited, but is preferably 0.01 to 5 parts by weight, more preferably 0.005 parts by weight with respect to the total amount of monomer components (100 parts by weight) constituting the acrylic polymer. 05 to 3 parts by weight.

  Although it does not specifically limit as heating temperature at the time of superposing | polymerizing by heating with the said solution polymerization method, For example, 50-80 degreeC is mentioned. Although it does not specifically limit as heating time, For example, 1 to 24 hours is mentioned.

  Although content of the said acrylic polymer in the adhesive composition which forms the said acrylic adhesive layer is not specifically limited, For example, it is 70 weight% or more with respect to the adhesive composition whole quantity (100 weight%). Preferably, it is 80% by weight or more, more preferably 90% by weight or more. When the content of the acrylic polymer in the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer is 70% by weight or more, the surface of the adherend after the surface protective film of the present invention is peeled off is another When the layer is provided, the adhesion between the adherend surface and the other layer is further increased.

Although the weight average molecular weight of the said acrylic polymer is not specifically limited, For example, 100,000-5 million are preferable, More preferably, it is 200,000-4 million, More preferably, it is 300,000-3 million. When the weight average molecular weight is less than 100,000, the cohesive force is reduced, and adhesive residue is generated on the surface of the adherend after peeling the surface protective film of the present invention, so that the adherend surface is uniformly wet after peeling. And sticky effects may not be obtained. When the weight average molecular weight exceeds 5,000,000, the wettability of the adherend surface after peeling the surface protective film of the present invention may be insufficient.
The said weight average molecular weight says what was obtained by measuring by the gel permeation chromatograph (GPC) method. More specifically, for example, as a GPC measuring device, the product name “HLC-8220GPC” (manufactured by Tosoh Corporation) is used for measurement under the following conditions, and the standard polystyrene equivalent can be calculated.
(Molecular weight measurement conditions)
Sample concentration: 0.2% by weight (tetrahydrofuran solution)
Sample injection volume: 10 μL
Sample column: TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
・ Reference column: TSKgel SuperH-RC (1)
・ Eluent: Tetrahydrofuran (THF)
・ Flow rate: 0.6mL / min
・ Detector: Differential refractometer (RI)
Column temperature (measurement temperature): 40 ° C

  Although the glass transition temperature (Tg) of the said acrylic polymer is not specifically limited, For example, 0 degrees C or less is preferable, More preferably, it is -10 degrees C or less. When glass transition temperature is higher than 0 degreeC, the wettability of the to-be-adhered body surface after peeling the surface protection film of this invention may become inadequate. In addition, the glass transition temperature of the said acrylic polymer can be adjusted by changing the composition ratio of the monomer component which comprises an acrylic polymer.

The glass transition temperature (° C.) can be obtained from the following formula as the glass transition temperature Tgn (° C.) of the homopolymer of each monomer.
1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[Wherein, Tg (° C.) is the glass transition temperature of the copolymer, Wn (−) is the weight fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer of each monomer, and n is the type of each monomer Represents. ]

The acid value of the acrylic polymer is not particularly limited, but is preferably 15 or less, for example. The acid value is measured using an automatic titration apparatus (Hiranuma Sangyo Co., Ltd., COM-550) and can be calculated from the following equation.
A = {(Y−X) × f × 5.611} / M
A: Acid value Y: Titration volume of sample solution (ml)
X: Titration volume of a solution containing only 50 g of mixed solvent (ml)
f; Factor of titration solution M; Weight of polymer sample (g).
The measurement conditions are as follows.
Sample solution: About 0.5 g of a polymer sample was dissolved in 50 g of a mixed solvent (toluene / 2-propanol / distilled water = 50 / 49.5 / 0.5, weight ratio) to obtain a sample solution.
Titration solution: 0.1N, 2-propanol potassium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd., for petroleum product neutralization value test)
Electrode: Glass electrode; GE-101, Comparative electrode; RE-201
Measurement mode: Petroleum product neutralization number test 1.

  The acrylic pressure-sensitive adhesive layer preferably further contains a surfactant from the viewpoint of further improving the wettability of the adherend surface after peeling off the surface protective film of the present invention. That is, it is preferable that the pressure-sensitive adhesive composition for forming the acrylic pressure-sensitive adhesive layer further contains a surfactant.

The surfactant is not particularly limited. For example, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene sorbitol fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl allyl ether , Nonionic surfactants such as polyoxyalkylene alkyl phenyl ethers, polyoxyalkylene derivatives, polyoxyalkylene alkyl amines, polyoxyalkylene alkyl amine fatty acid esters, sulfonates such as sodium alkylbenzene sulfonate, lauryl Alkyl sulfates such as sodium sulfate, dialkyl aryl sulfonates, sulfosuccinates such as alkali metal dialkyl sulfosuccinates, higher fats Anionic surface activity such as acid alkali metal salt, polyoxyalkylene alkyl ether sulfate ester salt, polyoxyalkylene alkyl ether phosphate ester salt, polyoxyalkylene alkyl phenyl ether sulfate ester salt, polyoxyalkylene alkyl phenyl ether phosphate ester salt Agents, cationic surfactants having an alkylene oxide group, amphoteric surfactants and the like. Moreover, you may have reactive substituents, such as a (meth) acryloyl group and an allyl group, in a molecule | numerator.
The said surfactant can be used individually or in combination of 2 or more types.

［式（１）中のＲは、炭素数１〜１２の炭化水素基（特に炭素数１０の炭化水素基や炭素数１２炭化水素基）を表し、Ｘはアニオン性親水基を表し、平均付加モル数ｎは３〜４０の数を表す。］

［式（２）中のＸはアニオン性親水基を表す。］
上記式（１）で挙げられる化合物及び上記（２）で挙げられる化合物におけるアニオン性親水基としては、上記式（ａ１）〜（ａ２）で表されるものがあげられる。 Among these, as the surfactant, when the surface protective film of the present invention is applied to an adherend, the surface of the adherend is easily transferred to the adherend surface, and the surface protective film of the present invention is peeled off. When providing other layers, an anionic surfactant is preferred from the viewpoint of further increasing the adhesion between the adherend surface and the other layers. Among them, examples of anionic surfactants that can provide particularly excellent effects include polyoxyalkylene alkyl phenyl ether sulfate esters (especially polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate), dialkyl sulfosuccinic acid alkali metal salts (particularly dioctyl sulfosuccinic acid). Sodium).
In addition, examples of the surfactant capable of obtaining an excellent effect include compounds represented by the following formulas (1) and (2).

[R in Formula (1) represents a hydrocarbon group having 1 to 12 carbon atoms (particularly a hydrocarbon group having 10 or 12 carbon atoms), X represents an anionic hydrophilic group, and average addition Mole number n represents the number of 3-40. ]

[X in Formula (2) represents an anionic hydrophilic group. ]
Examples of the anionic hydrophilic group in the compound mentioned in the above formula (1) and the compound mentioned in the above (2) include those represented by the above formulas (a1) to (a2).

  Examples of the compound represented by the formula (1) include polyoxyethylene-1- (allyloxymethyl) alkyl ether ammonium sulfate. Examples of the compound represented by the above formula (2) include polyoxyethylene styrenated phenyl ether ammonium sulfate.

  As the anionic surfactant, a general commercial product can be used. For example, trade name “AQUALON HS-10” (Daiichi Kogyo Seiyaku Co., Ltd.), trade name “Neocol P” (Daiichi Kogyo Seiyaku Co., Ltd.) ), Trade name “Haitenol N-08” (Daiichi Kogyo Seiyaku Co., Ltd.) and the like. In addition, the trade name “Hytenol NF-13” (Daiichi Kogyo Seiyaku Co., Ltd.), the trade name “Hytenol NF-17” (Daiichi Kogyo Seiyaku Co., Ltd.), and the trade name “AQUALON KH-10” (No. Ichi Kogyo Seiyaku Co., Ltd.).

Although the compounding quantity of the said surfactant is not specifically limited, For example, 0.1 to 4 weight% is preferable with respect to the total weight (100 weight%) of the adhesive composition which forms the said acrylic adhesive layer. More preferably, it is 0.15 to 3% by weight.
Moreover, the compounding amount of the surfactant is not particularly limited. For example, 0.2 to 4 parts by weight is preferable with respect to 100 parts by weight of the acrylic polymer, and more preferably 0.2 to 3 parts by weight. More preferably, it is 0.3-3 weight part. Especially, the compounding quantity (content) of an anionic surfactant has a preferable 0.2-4 weight part with respect to 100 weight part of said acrylic polymers, More preferably, 0.2-3 weight part, More preferably, it is 0.3-3 weight part. When the blending amount of the surfactant with respect to 100 parts by weight of the acrylic polymer is 0.2 parts by weight or more, the wettability of the adherend surface after peeling the surface protective film of the present invention is further improved. When the content is 4 parts by weight or less, when another layer is provided on the surface of the adherend after peeling off the surface protective film of the present invention, the adhesion between the adherend surface and the other layer is further increased.

The acrylic pressure-sensitive adhesive layer may further contain a crosslinking agent from the viewpoint that an appropriate cohesive force can be obtained. That is, the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer may further contain a crosslinking agent. The crosslinking agent is not particularly limited, and for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a melamine crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent are used. Of these, isocyanate crosslinking agents and epoxy crosslinking agents are preferred.
The said crosslinking agent is used individually or in combination of 2 or more types.

  Examples of the isocyanate crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate, and 2,4-triisocyanate. Aromatic isocyanates such as diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name “Coronate L” manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / Hexamethylene diisocyanate trimer adduct (trade name “Coronate HL” manufactured by Nippon Polyurethane Industry Co., Ltd.) Isocyanurate body (trade name "Coronate HX" manufactured by Nippon Polyurethane Industry Co.), and the like isocyanate adducts such as.

  Examples of the epoxy crosslinking agent include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, Methylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylenediamine (trade name “TETRAD-X” manufactured by Mitsubishi Gas Chemical Company), 1,3- Examples thereof include bis (N, N-diglycidylaminomethyl) cyclohexane (trade name “TETRAD-C” manufactured by Mitsubishi Gas Chemical Company, Inc.).

Although the compounding quantity of the said crosslinking agent is not specifically limited, For example, 0.01-15 weight% is preferable with respect to the total weight (100 weight%) of the adhesive composition which forms the said acrylic adhesive layer, More preferably, it is 0.5 to 10% by weight.
Moreover, the compounding quantity of the said crosslinking agent is although it does not specifically limit, For example, 0.01-15 weight part is preferable with respect to 100 weight part of said acrylic polymers, More preferably, 0.5-10 weight part, Furthermore, Preferably it is 2-9 weight part, Most preferably, it is 6-8 weight part. Since the cohesive force is obtained when the blending amount of the crosslinking agent with respect to 100 parts by weight of the acrylic polymer is 0.01 parts by weight or more, the adhesive remains on the surface of the adherend after peeling off the surface protective film of the present invention. Is less likely to occur, and uniform wettability and adhesiveness of the adherend surface after peeling can be obtained. By being 15 weight part or less, the wettability of the to-be-adhered body surface after peeling the surface protection film of this invention improves further. In particular, by being 6 to 8 parts by weight, it is possible to obtain both the uniform wettability of the adherend surface after peeling and the light peeling adhesiveness.

The acrylic pressure-sensitive adhesive layer may further contain a crosslinking catalyst. That is, the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer may further contain a crosslinking catalyst. The cross-linking catalyst is not particularly limited, and examples thereof include metal-based cross-linking catalysts (particularly tin-based cross-linking catalysts) such as tetra-n-butyl titanate, tetraisopropyl titanate, nursem ferric acid, butyl tin oxide, and dioctyl tin dilaurate. It is done.
The crosslinking catalyst may be used alone or in combination of two or more.

The blending amount of the crosslinking catalyst is not particularly limited. For example, 0.004 to 0.05% by weight is preferable with respect to the total weight (100% by weight) of the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer. More preferably, it is 0.004 to 0.03% by weight.
Moreover, the compounding quantity of the said crosslinking catalyst is although it does not specifically limit, For example, 0.001-0.05 weight part is preferable with respect to 100 weight part of said acrylic polymers, More preferably, it is 0.003-0.04. Parts by weight, more preferably 0.005 to 0.03 parts by weight. When the blending amount of the cross-linking catalyst with respect to 100 parts by weight of the acrylic polymer is within the above range, the cross-linking proceeds rapidly, and thus the productivity can be improved.

The acrylic pressure-sensitive adhesive layer may further contain a crosslinking retarder. That is, the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer may further contain a crosslinking retarder. The crosslinking retarder is not particularly limited. For example, β-ketoester such as methyl acetoacetate, ethyl acetoacetate, octyl acetoacetate, oleyl acetoacetate, lauryl acetoacetate, stearyl acetoacetate, acetylacetone, 2,4- Examples include β-diketones such as hexanedione and benzoylacetone. Of these, acetylacetone is preferred.
The said crosslinking retarder is used individually or in combination of 2 or more types.

The blending amount of the crosslinking retarder is not particularly limited, but is preferably 0.1 to 10% by weight with respect to the total weight (100% by weight) of the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer, More preferably, it is 0.1 to 3% by weight.
The amount of the crosslinking retarder is not particularly limited, but is preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, with respect to 100 parts by weight of the acrylic polymer. More preferably, it is 0.1-3 weight part. When the compounding quantity of the said crosslinking retarder with respect to 100 weight part of acrylic polymers is the said range, the pot life of an adhesive can be extended.

The pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer may further contain a solvent. That is, the pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer may be a solvent-based pressure-sensitive adhesive composition. As a solvent in the adhesive composition which forms the said acrylic adhesive layer, the solvent used for the above-mentioned solution polymerization method is mentioned, for example. The solvent in the pressure-sensitive adhesive composition for forming the acrylic pressure-sensitive adhesive layer may be the same as or different from the solvent used in the solution polymerization method.
The solvent in the pressure-sensitive adhesive composition for forming the acrylic pressure-sensitive adhesive layer can be used alone or in combination of two or more.

  The pressure-sensitive adhesive composition for forming the acrylic pressure-sensitive adhesive layer is a plasticizer, an anti-aging agent, a colorant (such as a pigment or a dye), an antistatic agent, or a tackifying resin as long as the effects of the present invention are not impaired. An additive may be included.

  The pressure-sensitive adhesive composition forming the acrylic pressure-sensitive adhesive layer is not particularly limited. For example, the acrylic polymer, the cross-linking agent, the cross-linking catalyst, the cross-linking retarder, and other additions added as necessary. It can be prepared by mixing agents and the like.

<Method for forming acrylic pressure-sensitive adhesive layer>
The acrylic pressure-sensitive adhesive layer in the surface protective film of the present invention is formed, for example, by a method (direct method) in which the pressure-sensitive adhesive composition is directly applied (applied) to the second surface of the substrate and dried or cured. Can do. The pressure-sensitive adhesive composition is applied (coated) to the surface (release surface) of the release liner and dried or cured to form an acrylic pressure-sensitive adhesive layer on the surface. It can be formed by a method of transferring the acrylic pressure-sensitive adhesive layer to a material film (transfer method). From the viewpoint of anchoring property of the acrylic pressure-sensitive adhesive layer, the direct method is usually preferable. When applying the pressure-sensitive adhesive composition, the field of surface protection film, such as roll coating method, gravure coating method, reverse coating method, roll brush method, spray coating method, air knife coating method, coating method using a die coater, etc. Conventionally known various methods may be used. The pressure-sensitive adhesive composition of the present invention can be dried under heating as necessary. For example, it can carry out by heating to 60-150 degreeC. In addition, examples of means for curing the pressure-sensitive adhesive composition of the present invention include irradiation with active energy rays such as ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, and electron beams.

  Although the thickness of the said acrylic adhesive layer is not specifically limited, 1-50 micrometers is preferable, More preferably, it is 1-35 micrometers, More preferably, it is 3-25 micrometers.

  The content of the acrylic polymer in the acrylic pressure-sensitive adhesive layer is not particularly limited. For example, it is preferably 75% by weight or more, more preferably, 100% by weight of the acrylic pressure-sensitive adhesive layer. It is 85% by weight or more, more preferably 90% by weight or more. When the content of the acrylic polymer in the acrylic pressure-sensitive adhesive layer is 90% by weight or more, when another layer is provided on the surface of the adherend after peeling off the surface protective film of the present invention, The adhesive force between the body surface and other layers is further increased.

  The surface of the acrylic pressure-sensitive adhesive layer in the surface protective film of the present invention may be protected by a release liner (separator). Although it does not specifically limit as a base material (liner base material) of the said release liner, For example, paper, a plastic film, etc. are mentioned. The plastic film (resin film) in the liner substrate is not particularly limited. For example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, Examples include polyester films (for example, polyethylene terephthalate film, polybutylene terephthalate film), polyurethane films, ethylene-vinyl acetate copolymer films, and the like. The surface of the liner substrate may be laminated with a polyolefin resin (for example, a polyethylene resin).

  A release agent (for example, silicone-based, fluorine-based, long-chain alkyl-based, fatty acid amide-based, etc.) or silica powder is used on the surface of the release liner to be bonded to the acrylic pressure-sensitive adhesive layer. Mold or antifouling treatment may be applied.

  Although the thickness of the said release liner is not specifically limited, For example, 5-200 micrometers is preferable, More preferably, it is 10-100 micrometers, More preferably, it is 15-30 micrometers.

  Although the thickness of the surface protection film of this invention is not specifically limited, For example, 25-220 micrometers is preferable, More preferably, it is 25-120 micrometers.

<Performance of surface protection film>
The surface protective film of the present invention has a peeling voltage measured within a measurement environment of 23 ° C. and 50% RH within ± 1 kV on the adherend (polarizing plate) side and the surface protective film side (more preferably ± 0). It is preferable that the antistatic performance is within 0.8 kV, more preferably within ± 0.7 kV. In particular, the peeling voltage measured under a measurement environment (low humidity environment) of 23 ° C. and 25% RH is within ± 1 kV (more preferably within ± 0.8 kV, more preferably, both on the adherend side and the surface protective film side). Is preferably within ± 0.7 kV). A surface protective film having a peel voltage at least on the surface protective film side within ± 0.1 kV in both the measurement conditions of 50% RH and 25% RH is preferable.

The surface protective film of the present invention may further contain other layers in addition to the base material, the topcoat layer and the acrylic pressure-sensitive adhesive layer. Examples of the arrangement of the “other layer” include a space between the first surface (back surface) of the substrate and the topcoat layer, a space between the second surface (front surface) of the substrate and the acrylic pressure-sensitive adhesive layer, and the like. . The layer disposed between the back surface of the substrate and the top coat layer may be, for example, a layer containing an antistatic component (antistatic layer). The layer disposed between the front surface of the base material and the acrylic pressure-sensitive adhesive layer is, for example, an undercoat layer (anchor layer) or an antistatic layer that improves the anchoring property of the acrylic pressure-sensitive adhesive layer with respect to the second surface. Also good. It may be a surface protective film having a configuration in which an antistatic layer is disposed on the front surface of the substrate, an anchor layer is disposed on the antistatic layer, and an acrylic pressure-sensitive adhesive layer is disposed thereon.
The surface protective film of the present invention may be, for example, a form wound in a roll shape or a form in which films are laminated.

  In the surface protective film of the present invention, for example, as shown in FIG. 1, it is preferable that the top coat layer 14 is directly provided on the back surface 12 </ b> A of the substrate 12. That is, it is preferable that no other layer (for example, an antistatic layer) is interposed between the back surface 12A of the base material and the top coat layer 14 (a top coat layer is provided on the first surface of the base material). According to such a configuration, the adhesion between the substrate back surface 12A and the top coat layer 14 can be improved as compared with a configuration in which another layer is interposed between the substrate back surface 12A and the top coat layer 14. Therefore, it becomes easy to obtain a surface protective film having more excellent scratch resistance.

  In the surface protective film of the present invention, for example, as shown in FIG. 1, it is preferable that an acrylic pressure-sensitive adhesive layer 20 is directly provided on the front surface 12 </ b> B of the substrate 12. That is, it is preferable that no other layer is interposed between the front surface 12B and the acrylic pressure-sensitive adhesive layer 20 (an acrylic pressure-sensitive adhesive layer is provided on the second surface of the substrate). By setting it as this structure, the adhesiveness of a base material and an acrylic adhesive layer improves.

  Moreover, the surface protective film of the present invention, for example, as shown in FIG. 3, affix the adhesive tape 60 to the back surface (surface of the topcoat layer 14) 1A of the surface protective film 1 attached to the adherend 50, The adhesive tape (pickup tape) 60 may be peeled off from the surface of the adherend by an operation (pickup operation) of pulling up at least a part of the surface protection film 1 from the adherend 50. Although it does not specifically limit as the pick-up tape 60, The single-sided adhesive tape provided with the base material (preferably resin film) 64 and the adhesive layer 62 provided in the single side | surface is preferable. The type of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 62 is not particularly limited. For example, various pressure-sensitive adhesives such as acrylic, polyester, urethane, polyether, rubber, silicone, polyamide, and fluorine are available. Can be mentioned. In addition, such various adhesives can be used individually or in combination of 2 or more types. Although the thickness of the adhesive layer 62 is not specifically limited, 3-100 micrometers is preferable, More preferably, it is 5-50 micrometers, More preferably, it is 10-30 micrometers.

Here, the adhesive strength of the pickup tape 60 to the back surface 1A of the surface protective film 1 (hereinafter sometimes referred to as “back surface peel strength”) varies greatly depending on the type of the adhesive constituting the adhesive layer 62. The degree of freedom of selection of the pickup tape 60 to be used may be low. Moreover, the difference in the back surface peel strength may confuse an operator who removes the surface protection film 1 from the adherend 50 using the pickup tape 60, and may cause a reduction in work efficiency and an increase in work load. On the other hand, general pickup tapes are acrylic pickup tapes having an adhesive layer (acrylic adhesive layer) made of an acrylic adhesive, and an adhesive layer made of a rubber adhesive, from the viewpoint of availability and cost. There are many rubber-type pickup tapes provided with (rubber-type adhesive layer). Therefore, a surface protective film that exhibits relatively close back peel strength to these two typical types of pickup tapes is preferable.
The topcoat layer according to the surface protective film of the present invention contains a wax ester as a slip agent. The topcoat layer having such a composition has a smaller difference in backside peel strength depending on the type of the pressure-sensitive adhesive layer of the pick-up tape as compared with, for example, a topcoat layer having a composition containing a silicone lubricant instead of the wax ester (that is, backside peel off). This is preferable because the dependency on the strength of the pickup tape adhesive is small.

  The base material of the said pick-up tape should just have the intensity | strength and the softness | flexibility which can perform the said pick-up operation, and is not specifically limited. For example, a resin film similar to the base material of the surface protective film is preferably exemplified. In addition, rubber sheets made of natural rubber, butyl rubber, etc .; foam sheets made by foaming polyurethane, polychloroprene rubber, polyethylene, etc .; papers such as kraft paper, crepe paper, Japanese paper; cloths such as cotton cloth and soft cloth; Nonwoven fabrics such as cellulose-based nonwoven fabric, polyester nonwoven fabric, and vinylon nonwoven fabric; metal foils such as aluminum foil and copper foil; and composites thereof. Although the thickness of the base material of the said pickup sheet | seat can be suitably selected according to the objective, 10-500 micrometers is preferable, More preferably, it is 10-200 micrometers.

  In the surface protective film according to a preferred embodiment, the back surface peel strength of a pickup tape having an acrylic pressure-sensitive adhesive layer (for example, trade name “No. 31B” manufactured by Nitto Denko Corporation) is Fa (N / 20 mm), and rubber-based When the backside peel strength of a pickup tape having an adhesive layer (for example, trade name “Cellotape (registered trademark)” manufactured by Nichiban Co., Ltd.) is Fr (N / 20 mm), | Fa−Fr | N / 20 mm) or less, more preferably 1.2 (N / 20 mm) or less, and even more preferably 1.0 (N / 20 mm) or less. The surface protective film having such characteristics has a small dependency of the back surface peel strength on the pickup tape adhesive. Therefore, it is preferable because the feeling of use in the pickup operation is good.

  The back surface peel strength was measured at 23 ° C. and 50% RH. A pick-up tape was attached to the back surface of the surface protective film and allowed to stand for 30 minutes. It can be obtained by peeling off under conditions of 3 m / min and a peeling angle of 180 degrees and measuring the peel strength at this time. When the width W1 (mm) of the pickup tape used for measurement is different from 20 mm, the peel strength can be converted to a peel strength at a width of 20 mm by multiplying the peel strength by 20 / W1. Usually, it is preferable to measure the back surface peel strength using a pickup tape having a width of 10 to 30 mm (for example, 15 to 25 mm).

  The back surface peel strengths Fa and Fr are both preferably 3.0 N / 20 mm or more, more preferably 4.0 N / 20 mm or more, and still more preferably 5.0 N / 20 mm or more. If the back surface peel strength is too low, the surface protection film cannot be picked up from the surface of the adherend, and the pickup tape may be peeled off from the back surface of the surface protection film. The upper limit of the back surface peel strength is not particularly limited. Usually, it is appropriate that both Fa and Fr are 20 N / 20 mm or less (for example, 10 N / 20 mm or less).

The surface protective film according to a preferred embodiment is a smaller one of the back surface peel strengths Fa and Fr (hereinafter sometimes referred to as “(Fa, Fr) min”. The unit is N / 20 mm). The surface protective film is pressure-bonded to an adherend (typically a polarizing plate) and allowed to stand for 30 minutes, and then peeled off from the adherend under conditions of a peeling rate of 0.3 m / min and a peeling angle of 180 °. The relationship with the measured peel strength Fp (N / 25 mm) preferably satisfies the following formula: [(Fa, Fr) min / Fp] ≧ 5. If (Fa, Fr) min / Fp is too small, the surface protection film cannot be picked up from the surface of the adherend, and the pickup tape may be peeled off from the back surface of the surface protection film. In order to perform the pickup operation more efficiently, (Fa, Fr) min / Fp is preferably 8 or more, more preferably 10 or more, still more preferably 25 or more, and particularly preferably 50 or more. The upper limit of the value of (Fa, Fr) min / Fp is not particularly limited, but is preferably 200 or less.
The peel strength Fp (N / 25 mm) is the adherend surface of the surface protective film (test piece) cut into a long shape with an appropriate width under the measurement conditions of 23 ° C. and 50% RH. It is obtained by sticking to (for example, a plain polarizing plate) and leaving it for 30 minutes, then peeling off under conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 °, and measuring the peel strength at this time. When the width W2 (mm) of the surface protective film used for the measurement is different from 25 mm, it can be converted to a peel strength at a width of 25 mm by multiplying the peel strength by 25 / W2. Usually, it is preferable to measure the peel strength Fp using a test piece having a width of 10 to 30 mm (for example, 20 to 30 mm).

  The topcoat layer in the surface protective film of the present invention contains a specific wax (that is, an ester of a higher fatty acid and a higher alcohol) as a slipping agent and a polyester resin as its binder, so even under high temperature and high humidity conditions. Whitening of the topcoat layer can be effectively suppressed. A base material having such a topcoat layer on the back side has a slipping agent and thus has good scratch resistance and can be excellent in whitening resistance. Therefore, the surface protective film provided with the said base material can become a thing with a higher appearance quality.

  The surface protective film of the present invention has a water contact angle A on the surface of the adherend X of 70 ° or less (for example, 50 to 50) after the surface protective film of the present invention is attached to the surface of the adherend X and peeled off. 70 ° or the like).

  In addition to the adherend X, the surface protective film of the present invention can be contacted with water on the surface of the adherend after the surface protective film of the present invention is peeled off even when it is attached to an adherend such as an acrylic plate. When the other surface is provided on the surface of the adherend on which the surface protection film has been attached, the surface of the adherend can be in a state in which the adherend surface is excellent in wettability with respect to the other layer. .

  The surface protective film of the present invention is a surface protective film capable of making the adhesive strength A higher than the adhesive strength B.

In general, when peeling off the surface protective film affixed to the adherend, a part of the adhesive layer of the surface protective film remains on the adherend, and due to contamination of the adherend surface, When a layer is provided, the adhesion (adhesiveness) between the adherend surface and other layers often decreases. However, the surface protective film of the present invention improves the adhesion of the adherend surface after the surface protective film of the present invention is peeled off.
When the surfactant is contained in the pressure-sensitive adhesive composition, the water contact angle after the surface protective film of the present invention is peeled off tends to be low due to the surfactant moving to the adherend surface. Excellent wettability. Further, the repellency of other layers is reduced. In particular, since an anionic surfactant easily moves to the surface of an adherend, the effect of improving wettability with respect to other layers is great. In particular, when the acrylic pressure-sensitive adhesive layer contains an acrylic polymer and an anionic surfactant, the anionic surfactant and the acrylic polymer migrate to the adherend surface, and the anionic surfactant and the acrylic system are transferred. The polymer interacts to improve the adhesion to other layers, or the wettability of the adherend surface to other layers is further improved, and the adhesion between the adherend surface and other layers is further improved. Excellent. In particular, this effect can be obtained uniformly over the entire adherend, unlike the case where a part of the pressure-sensitive adhesive is peeled off.

  The surface protective film of the present invention is not particularly limited, but, for example, optical properties (for example, polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation) The surface of the adherend is applied to the surface of the adherend to which the surface protective film of the present invention has been attached after the surface of the member having visibility, etc. is protected and peeled. It is used for applications in which the body surface is excellent in wettability to other layers and the adhesion between the adherend surface and other layers is excellent, and / or in the appearance inspection of products performed through a surface protective film. That is, a surface protective film for a member having optical characteristics is preferable, and a surface protective film for improving the surface protection, wettability, and adhesion of a member having optical characteristics is more preferable.

  The surface protective film of the present invention is, for example, in the production of an optical member used as a component of a liquid crystal display panel, a plasma display panel (PDP), an organic electroluminescence (EL) display, a touch panel display, a field emission display, or the like during transportation. It is suitable for use for protecting the optical member. That is, the surface protective film of the present invention is preferably used, for example, for optical members (surface protective films for optical members), optical components (surface protective films for optical components), and the like.

  Although it does not specifically limit as said optical member, For example, the member which comprises optical products, such as a display apparatus (image display apparatus) and an input device, or the member used for these apparatuses (optical products) is mentioned, Specifically, Polarizing plate, wave plate, retardation plate, optical compensation film, brightness enhancement film, light guide plate, reflection film, antireflection film, transparent conductive film (ITO film, ITO glass, etc.), design film, decorative film, surface protection Examples thereof include a plate, a prism, a lens, a color filter, a transparent substrate, a light diffusion sheet, a reflection sheet, and a member in which these are laminated. Among them, an optical member such as a polarizing plate (polarizing film), a wave plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light diffusion sheet, and a reflecting sheet is preferable, and a polarizing plate for a liquid crystal display panel is particularly preferable. Is the adherend X.

  The method for providing another layer on the adherend from which the surface protective film of the present invention has been peeled is not particularly limited. For example, the step of applying the surface protective film of the present invention to the adherend (sticking step), the present invention And a method including a step of peeling the surface protective film from the adherend (peeling step) and a step of providing another layer on the surface of the adherend (step of providing another layer).

  Examples of the adherend in the attaching step include a member having the above-described optical characteristics. Among these, the adherend X is preferable. As temperature and pressure at the time of affixing the surface protection film of the present invention on the adherend, for example, temperature 0 to 50 ° C., pressure 1 to 10 atm may be mentioned.

  After the sticking step, a step of standing at a temperature of 0 to 50 ° C. for 1 to 120 hours (a standing step) may be included. By the process of leaving still, the component which improves adhesiveness from the surface protection film of this invention becomes easier to transcribe | transfer to an adherend surface.

  In the said peeling process, as peeling conditions, the tensile speed of 300-100000 mm / min and the peeling angle (tensile angle) 90-180 degrees are mentioned, for example. The temperature in the peeling step may be the same as or different from the pasting step or the standing step. As temperature in a peeling process, temperature 0-50 degreeC is mentioned, for example.

The process of providing the said other layer may be provided continuously to the said peeling process, and a space | interval (for example, 1 to 24 hours) may be left | separated.
Examples of the other layer in the step of providing the other layer include those described above. Among these, a layer provided by applying the interlayer filler is preferable.

  According to the method of providing another layer on the adherend to which the surface protective film of the present invention is attached, the adherend and the other layer are excellent in adhesion.

[Optical member]
The optical member of the present invention includes the surface protective film of the present invention. As the optical member of the present invention, for example, the surface protective film of the present invention is pasted on a member constituting an optical product such as a display device (image display device) or an input device or a member used in these devices (optical product). Things. As a member constituting an optical product or a member used in these devices, for example, a polarizing plate, a wavelength plate, a retardation plate, an optical compensation film, a brightness enhancement film, a light guide plate, a reflection film, an antireflection film, a transparent conductive film (ITO film, ITO glass, etc.), design film, decorative film, surface protective plate, prism, lens, color filter, transparent substrate, and a member in which these are laminated. Among these, a polarizing plate is preferable.

In the optical member of the present invention, one surface protective film of the present invention may be affixed, or two or more surface protective films of the present invention may be affixed.
In the optical member of the present invention, the entire surface of the member may be covered with a surface protective film, or a part of the surface may be covered with the surface protective film. Among these, from the viewpoint of cost, it is preferable to provide a surface protective film only on a surface that is easily damaged in transportation and assembly processes.
In addition, the shape and magnitude | size of the surface protection film of this invention stuck are not specifically limited. Further, the method for applying the surface protective film of the present invention is not particularly limited.

  Although the optical member of the present invention is not particularly limited, for example, optical properties (for example, polarization, light refraction, light scattering, light reflection, light transmission, light absorption, light diffraction, optical rotation, It is preferable to have visibility.

  According to the optical member of the present invention, since the appearance inspection can be performed with the surface protective film attached, the efficiency of the appearance inspection is improved. Further, the portion provided with the surface protection film is hardly damaged, and the efficiency of transportation and product assembly work is improved.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited at all by these. Moreover, each characteristic in the following description was measured or evaluated as follows.

1. Evaluation of whitening resistance The back of the surface protective film obtained in the Examples and Comparative Examples (surface of the topcoat layer) was rubbed once by a gloved tester with a 38 μm thick polyethylene terephthalate film. It was visually observed whether or not the portion (rubbed portion) was more transparent than the surrounding (non-rubbed portion). As a result, when the difference in transparency between the non-rubbed part and the scratched part could be visually confirmed, it was determined that whitening was observed. When whitening becomes remarkable, a phenomenon in which the contrast between the transparent rubbing portion and the surrounding area (whitening non-rubbing portion) becomes clearer is observed.
The visual observation was performed in a dark room (reflection method, transmission method) and a bright room as follows.
(A) Observation by a reflection method in a dark room: in a room (dark room) where outside light is blocked, a 100 W fluorescent lamp (Mitsubishi) at a position 100 cm from the back surface (the surface of the topcoat layer) according to each example. Denki Co., Ltd., trade name “Lupica Line”) was placed, and the back of the sample was visually observed while changing the viewpoint.
(B) Observation by a transmission method in a dark room: In the dark room, the fluorescent lamp is placed at a position 10 cm from the front surface (the surface opposite to the side on which the topcoat layer is provided) of the surface protective film, and the viewpoint The back of the sample was visually observed while changing.
(C) Observation in a bright room: In a room (light room) having a window where external light enters, the back surface of the sample was visually observed on a sunny day and a window that was not exposed to direct sunlight.
The observation results under these three types of conditions are expressed in the following five stages.
0: No whitening (the rubbing portion and the non-rubbing portion were transparent) was not observed under any of the observation conditions.
1: Slight whitening was observed in the observation by the reflection method in a dark room.
2: Slight whitening was observed in the observation by the transmission method in a dark room.
3: Slight whitening was observed in observation in a bright room.
4: Clear whitening was observed in observation in a bright room.
The whitening resistance evaluation described above was initially (after preparation, held for 3 days under conditions of 50 ° C. and 15% RH) and after heating and humidification (after preparation, maintained under conditions of 50 ° C. and 15% RH for 3 days) And a surface protective film of 60 ° C. and 95% RH held for 2 weeks under high temperature and high humidity conditions.

2. Appearance of the surface protective film Before making the surface protective film, for the base material with a topcoat used for the surface protective film, in a room (light room) with a window to which external light enters, in the daylight that is not exposed to direct sunlight. The back surface (surface on the topcoat layer side) was visually observed. And the thing with which the nonuniformity and the stripe were not confirmed evaluated that the external appearance of the base material with a topcoat was favorable, and the external appearance of the base material with a topcoat was evaluated as poor when the unevenness and the stripe were confirmed.
Next, after the surface protective film was prepared, the surface state of the acrylic pressure-sensitive adhesive layer surface of the surface protective film was visually observed, and the number of defects (dents and bubbles) within the observation range of 10 cm in length and 10 cm in width was measured. And when the number of appearance defects is 0 to 100, the appearance of the acrylic pressure-sensitive adhesive layer is evaluated as good, and when the number of appearance defects is 101 or more, the appearance of the acrylic pressure-sensitive adhesive layer is poor. evaluated.
And when both the external appearance of the base material with a topcoat and the external appearance of an acrylic adhesive layer can be evaluated as favorable, the surface protective film external appearance was evaluated as favorable "(circle)". On the other hand, when both the appearance of the substrate with the top coat and the appearance of the acrylic pressure-sensitive adhesive layer can be evaluated as poor, the appearance of the substrate with the top coat can be evaluated as good, and the appearance of the acrylic pressure-sensitive adhesive layer is evaluated as poor. When it was possible, and when the appearance of the substrate with the topcoat could be evaluated as poor, and the appearance of the acrylic pressure-sensitive adhesive layer could be evaluated as good, the surface protective film appearance was evaluated as defective “x”.

3. Evaluation of solvent resistance In the above dark room, the back surface of the surface protective film obtained in Examples and Comparative Examples (ie, the surface of the topcoat layer) was wiped with a cloth (cloth) soaked with ethyl alcohol five times, and the back surface thereof. The appearance of was visually observed. As a result, when no difference in appearance was observed between the part wiped with ethyl alcohol and other parts (when no change in appearance due to wiping with ethyl alcohol was observed), the solvent resistance " When “good” and uneven wiping were confirmed, the solvent resistance was evaluated as “bad”.

4). 4. Back surface peel strength measurement As shown in FIG. 4, the surface protective film 1 obtained in Examples and Comparative Examples was cut into a size of 70 mm in width and 100 mm in length, and the acrylic adhesive surface (acrylic type) of the surface protective film 1 20A was fixed on the SUS304 stainless steel plate 132 using the double-sided adhesive tape 130.
A single-sided adhesive tape having a natural rubber adhesive 162 on a cellophane film (base material) 164 (trade name “Cello Tape (registered trademark)”, manufactured by Nichiban Co., Ltd., width 24 mm) was cut to a length of 100 mm. The pressure-sensitive adhesive surface 162A of the pressure-sensitive adhesive tape 160 was pressure-bonded to the back surface (that is, the surface of the topcoat layer 14) 1A of the surface protective film 1 at a pressure of 0.25 MPa and a speed of 0.3 m / min. This was left under conditions of 23 ° C. and 50% RH for 30 minutes. Thereafter, using a universal tensile testing machine, the adhesive tape 160 was peeled from the back surface 1A of the surface protective film 1 under the conditions of a peeling speed of 0.3 m / min and a peeling angle of 180 degrees, and the peel strength at this time [N / 24 mm ] Was measured.
The double-sided pressure-sensitive adhesive tape 130 is pulled by the pressure-sensitive adhesive tape 160 when the pressure-sensitive adhesive tape 160 is peeled from the back surface A of the surface protective film 1 in order to more accurately measure the back surface peel strength. It is used for the purpose of preventing floating from the stainless steel plate 132, and can be appropriately selected and used for the purpose. Here, the product name “No. 500A” manufactured by Nitto Denko Corporation was used.

5. Water contact angle The surface protective film obtained in Examples and Comparative Examples was attached to the surface of an adherend (hard coat film) at a temperature of 23 ° C. and a humidity of 30%, and then placed in an autoclave and a temperature of 50 ° C. Then, the film was treated and adhered under the conditions of a pressure of 5 atm and a time of 15 minutes. Using a water contact angle measuring device (trade name “DM700”, manufactured by Kyowa Interface Chemical Co., Ltd.), an adherend to which a surface protective film was adhered in an atmosphere of a temperature of 23 ° C. and a humidity of 30% RH by a liquid suitable method. About 2.8 μL of water droplets were dropped on the surface, and the angle formed by the tangent line between the adherend surface and the end of the dropped water droplet 1 second after the dropping was measured to obtain the “water contact angle (°)”. The case where the water contact angle was 70 ° or less was evaluated as “good”, and the case where it was larger than 70 ° was evaluated as “bad”.
The water contact angle of the adherend not subjected to any treatment was 87.6 °. That is, the adherend used in this evaluation is a hard coat film having a water contact angle of 87.6 °.

6). Acrylic tape No. Adhesive strength of 31B The surface protective film obtained in Examples and Comparative Examples was attached to the surface of an adherend (hard coat film) at a temperature of 23 ° C. and a humidity of 30%, and then placed in an autoclave to obtain a temperature of 50 The surface protective film was peeled off by treatment under conditions of ℃, pressure of 5 atm, and time of 15 minutes, and allowed to stand for 12 hours at a temperature of 23 ℃ and a humidity of 30%. Thereafter, an adhesive surface of an acrylic tape piece (manufactured by Nitto Denko Corporation, product number No. 31B, base material thickness 25 μm) having a length of 70 mm and a width of 19 mm is applied to the adherend surface to which the surface protective film has been bonded, at a temperature of 23 ° C. Affixed at 30% humidity and bonded at 0.25 MPa, 300 mm / min, allowed to stand at a temperature of 23 ° C. and a humidity of 30% for 30 minutes, and then 180 ° peel adhesive strength (temperature) 23 ° C., humidity 30% RH, peeling angle 180 °, tensile speed 300 mm / min) (N / 19 mm), and the obtained value was defined as “adhesive strength of acrylic tape No. 31B (N / 19 mm)”. .
Acrylic tape No. for adherends that have not been treated. The adhesive strength (N / 19 mm) of 31B was 6.91 N / 19 mm.
Acrylic tape No. for the adherend after peeling off the surface protective film. The case where the adhesive strength (N / 19 mm) of 31B was higher than 6.91 N / 19 mm was evaluated as good “◯”, and the case where it was 6.91 N / 19 mm or less was evaluated as defective “X”.
The adherend used in this evaluation is the same as the adherend used in the evaluation of “5. Water contact angle”.

7). Interlayer filler wettability The surface protective films obtained in the examples and comparative examples were attached to the surface of the adherend at a temperature of 23 ° C. and a humidity of 30%, and then placed in an autoclave, where the temperature was 50 ° C. and the pressure. The treatment was carried out under conditions of 5 atm and 15 minutes, and the mixture was allowed to adhere, and allowed to stand at a temperature of 23 ° C. and a humidity of 30% for 12 hours. Thereafter, the adherend to which the surface protective film was attached was cut out to a length of 40 mm and a width of 40 mm, and attached to a glass plate having a length of 50 mm and a width of 50 mm, and the glass plate was attached to a spin coater (trade name “K-359SD1”). , Manufactured by Kyowa Riken Co., Ltd.). Thereafter, the surface protective film is peeled off from the adherend, and 4 ml of a trade name “SVR7000 series” (manufactured by Dexerials) is applied as an interlayer filler to the adherend surface to which the surface protective film has been applied. Rotated to evenly stretch the interlayer filler. After standing at a temperature of 23 ° C. and a humidity of 30% for 1 hour, the distance at which the interlayer filler was repelled from the edge of the adherend was measured with a ruler.
Moreover, the same measurement was performed using a brand name "WORD ROCK HRJ-21" (made by Kyoritsu Chemical Industry Co., Ltd.) as an interlayer filler.
When using any of the interlayer fillers of “SVR7000 series” and “WORD ROCK HRJ-21”, the case where the distance repelled from the edge is shorter than 2 mm is good “◯”, either one or both interlayer fillers In the case where the distance from the edge is 2 mm or more, the case where the distance was used was evaluated as a defective “x”.
The adherend that had not been subjected to any treatment was defective “x”. The adherend used in this evaluation is the same as the adherend used in the evaluation of “5. Water contact angle”.

8). Adhesiveness of interlayer filler The surface protective films obtained in Examples and Comparative Examples were attached to the surface of the adherend at a temperature of 23 ° C. and a humidity of 30%, and then put into an autoclave to be heated to a temperature of 50 ° C. and a pressure. The surface protection film was peeled off by treatment at 5 atm for 15 minutes and allowing to adhere to the film at a temperature of 23 ° C. and a humidity of 30% for 12 hours.
Using an applicator, an interlayer filler (trade name “SVR7000 Series” manufactured by Dexials) is applied to the surface of the adherend to which the surface protective film has been applied so as to have a thickness of 100 μm. Covered with PET film to avoid touching. Then, UV of 5000 mJ or more was irradiated to cure the interlayer filler. After curing, it was cut into a size of 70 mm in length and 25 mm in width. Using a tensile tester, the 180 ° peel adhesion (temperature 23 ° C., humidity 30% RH, peeling angle 180 °, tensile speed 300 mm / min) (N / 25 mm) of the layer composed of the interlayer filler to the adherend is measured. It was measured.
Moreover, the same measurement was performed using a brand name "WORD ROCK HRJ-21" (made by Kyoritsu Chemical Industry Co., Ltd.) as an interlayer filler.
On the other hand, an optical transparent adhesive tape was prepared by peeling off a light release separator of an optical transparent adhesive tape (trade name “LUCIACS CS9886U” manufactured by Nitto Denko Corporation), attaching a PET film, and cutting it into a length of 70 mm and a width of 25 mm. . The optical transparent pressure-sensitive adhesive tape is attached to the surface of the adherend to which the surface protective film has been attached, after peeling the heavy release separator of the optical transparent pressure-sensitive adhesive tape and peeling the surface protective film in the same manner as described above. The pressure-sensitive adhesive surface was affixed at a temperature of 23 ° C. and a humidity of 30%, pressure-bonded at 0.25 MPa and 300 mm / min, and allowed to stand at a temperature of 23 ° C. and a humidity of 30% for 30 minutes. Then, using a tensile tester, 180 ° peel adhesive strength of the optical transparent adhesive tape to the adherend (temperature 23 ° C., humidity 30% RH, peeling angle 180 °, tensile speed 300 mm / min) (N / 25 mm) Was measured.
The adhesion of the interlayer filler is such that the 180 ° peel adhesive strength of the layer made of the interlayer filler to the adherend is higher than 1.47 N / 25m, and the 180 ° peel adhesive strength of the optical transparent adhesive tape to the adherend. Is higher than 16.7 N / 25 mm (a product for an adherend in which the 180 ° peel adhesive strength of the layer consisting of the product name “SVR7000 series” on the adherend surface to which the surface protective film has been applied has not been treated at all) 180 ° peel adhesive strength of the layer consisting of the product name “WORD ROCK HRJ-21” which is higher than the 180 ° peel adhesive strength of the layer consisting of the name “SVR7000 series” and to which the surface protective film is attached. Higher than the 180 ° peel adhesive strength of the layer consisting of the trade name “WORD ROCK HRJ-21” for the adherend not treated with And the 180 ° peel adhesive strength of the optical transparent adhesive tape to the adherend surface to which the surface protective film has been applied is higher than the 180 ° peel adhesive strength to an untreated adherend) Good “◯”, when the 180 ° peel adhesive strength of the layer made of the interlayer filler to the adherend is 1.47 N / 25 m or less, and / or 180 ° peel adhesive strength of the optical transparent adhesive tape to the adherend The case of 16.7 N / 25 mm or less was evaluated as a defective “x”.
In addition, the 180 degree peel adhesive strength of the layer consisting of the trade name “SVR7000 series” with respect to the adherend not subjected to any treatment was 1.47 N / 25 mm.
Further, the 180 ° peel adhesive strength of the optical transparent adhesive tape to the adherend not subjected to any treatment was 16.7 N / 25 mm. The adherend used in this evaluation is the same as the adherend used in the evaluation of “5. Water contact angle”.

(Example 1)
(Preparation of coating agent)
A dispersion containing 25% of a polyester resin as a binder (trade name “Vinaroll MD-1480” manufactured by Toyobo Co., Ltd., (a water dispersion of a saturated copolymerized polyester resin) (binder dispersion) was also prepared. An aqueous dispersion (slipper dispersion) of carnauba wax (wax ester) was prepared, and poly (3,4-dioxythiophene) (PEDOT) 0.5% as a conductive polymer and polystyrene sulfonate (several) An aqueous solution (trade name “Baytron P”, product of HC Stark Co., Ltd.) (conductive polymer aqueous solution) containing 0.8% of average molecular weight (150,000) (PSS) was prepared.
In a mixed solvent of water and ethanol, 100 parts of the binder dispersion liquid as a solid content, 30 parts of the slip agent dispersion liquid as a solid content, 50 parts of the conductive polymer aqueous solution as a solid content, and melamine-based crosslinking The agent was added and mixed well by stirring for about 20 minutes. In this way, a coating agent having an NV of about 0.15% was prepared.

(Formation of top coat layer)
A transparent polyethylene terephthalate (PET) film having a thickness of 38 μm, a width of 30 cm, and a length of 40 cm, which was subjected to corona treatment on one surface (first surface), was prepared. The coating agent was applied to the corona-treated surface of this PET film with a bar coater, and dried by heating to 130 ° C. for 2 minutes. Thus, the base material (base material with a topcoat) which has a transparent topcoat layer with a thickness of 10 nm on the first surface of the PET film was produced.

(Preparation of adhesive composition)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube and a condenser, 200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, and 2,2′-azobis as a polymerization initiator Charge 0.4 parts by weight of isobutyronitrile and 312 parts by weight of ethyl acetate as a solvent, introduce nitrogen gas while gently stirring, and perform a polymerization reaction for 6 hours while maintaining the liquid temperature in the flask at around 65 ° C. An acrylic polymer solution (40% by weight) was prepared. The acrylic polymer had a weight average molecular weight of 540,000, a glass transition temperature (Tg) of −68 ° C., and an acid value of 0.0.
The acrylic polymer solution (40% by weight) is diluted to 20% by weight with ethyl acetate, and polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (an anionic surfactant) is added to 100 parts by weight of the solid content in the solution. 0.3 part by weight of trade name “AQUALON HS-10” (Daiichi Kogyo Seiyaku Co., Ltd.), 3 parts by weight of isocyanurate of hexamethylene diisocyanate (trade name “Coronate HX”, manufactured by Nippon Polyurethane Industry Co., Ltd.) 0.03 part by weight of dibutyltin dilaurate (trade name “OL-1”, manufactured by Tokyo Fine Chemical Co., Ltd., 0.5 wt% ethyl acetate solution) as a crosslinking catalyst, 3 parts by weight of acetylacetone as a crosslinking retarder with respect to the total amount of solvent The mixture was stirred and mixed to prepare an acrylic pressure-sensitive adhesive composition.

(Production of surface protective film)
A release sheet having a release treatment with a silicone release treatment agent on one side of a PET film was prepared. The acrylic pressure-sensitive adhesive composition was applied on the release surface of the release sheet (the surface subjected to the release treatment) and dried to form an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm. After the acrylic pressure-sensitive adhesive layer was bonded to the other surface (the second surface, ie, the surface where the topcoat layer was not provided) of the substrate with the topcoat, in an environment of 50 ° C. and 15% RH. The surface protective film was obtained by aging for 3 days.

(Example 2)
A coating agent having an NV of about 0.3% was prepared using the same binder dispersion, slip agent dispersion, conductive polymer aqueous solution, and melamine-based crosslinking agent as in Example 1.
A substrate (substrate with a topcoat) having a transparent topcoat layer with a thickness of 50 nm on the first surface of the PET film was prepared in the same manner as in Example 1 except that the thickness of the topcoat layer was 50 nm. did. Anionic surfactant polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. Acrylic pressure-sensitive adhesive composition was prepared in the same manner as in Example 1 except that 0.7 parts by weight of the product was added. A surface protective film was obtained in the same manner as in Example 1 using the base material with a top coat and the acrylic pressure-sensitive adhesive composition.

Example 3
Anionic surfactant polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 2 except that 2 parts by weight of the product was added.

Example 4
Instead of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “Aqualon HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), anionic surfactant sodium dioctyl sulfosuccinate (trade name “Neocol P”, Daiichi Kogyo Seiyaku Co., Ltd.) was added in the same manner as in Example 2 except that 0.3 part by weight was added to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. And a surface protective film were prepared.

(Example 5)
Anionic surfactant sodium dioctylsulfosuccinate (trade name “Neocol P”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to 100 parts by weight of a solid content in an acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 4 except that 5 parts by weight was added.

(Example 6)
3 weights of sodium dioctyl sulfosuccinate (trade name “Neocol P”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), an anionic surfactant, with respect to 100 parts by weight of solid content in an acrylic polymer solution diluted to 20% by weight An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 4 except for adding part.

(Example 7)
1 weight of sodium dioctyl sulfosuccinate (trade name “Neocol P”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), an anionic surfactant, is added to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 4 except for adding part.

(Example 8)
Instead of 0.3 parts by weight of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyoxyethylene styrenated phenyl ether ammonium sulfate (an anionic surfactant) An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 1 except that 0.5 parts by weight of trade name “Hytenol NF-13” (Daiichi Kogyo Seiyaku Co., Ltd.) was used.

Example 9
Instead of 0.3 parts by weight of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyoxyethylene styrenated phenyl ether ammonium sulfate (an anionic surfactant) An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 1 except that 0.5 parts by weight of trade name “Hytenol NF-17” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used.

(Example 10)
Instead of 0.3 parts by weight of polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “Aqualon HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polyoxyethylene-1- (allyloxymethyl) alkyl ether ammonium sulfate (product An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 1 except that 0.5 part by weight of “AQUALON KH-10” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used.

(Comparative Example 1)
An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 2 except that the surfactant was not added.

(Comparative Example 2)
Anionic surfactant polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were prepared in the same manner as in Example 2 except that 0.1 part by weight of the product was added.

(Comparative Example 3)
Anionic surfactant polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 2 except that 5 parts by weight of the product was added.

(Comparative Example 4)
Anionic surfactant sodium dioctyl sulfosuccinate (trade name “Neocol P”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to 100 parts by weight of a solid content in an acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 4 except that 1 part by weight was added.

(Comparative Example 5)
5 weights of anionic surfactant sodium dioctyl sulfosuccinate (trade name “Neocol P”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. An acrylic pressure-sensitive adhesive composition and a surface protective film were produced in the same manner as in Example 4 except for adding part.

(Comparative Example 6)
Anionic surfactant polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. (Except for adding 0.7 parts by weight), nonionic surfactant polyoxyalkylene alkenyl ether (trade name “Ramtel PD-420”, manufactured by Kao Corporation) was added except that 1 part by weight was added. In the same manner as in Example 2, an acrylic pressure-sensitive adhesive composition and a surface protective film were produced.

(Comparative Example 7)
Anionic surfactant polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “AQUALON HS-10”, Daiichi Kogyo Seiyaku Co., Ltd.) with respect to 100 parts by weight of the solid content in the acrylic polymer solution diluted to 20% by weight. (Commercially available) 0.7 parts by weight, a product that is a nonionic surfactant instead of adding 3 parts by weight of isocyanurate of hexamethylene diisocyanate (trade name “Coronate HX”, manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent The name “Adeka Pluronic 25R-1” (manufactured by ADEKA Corporation) 0.7 parts by weight, and 4 parts by weight of hexamethylene diisocyanate isocyanurate (trade name “Coronate HX”, manufactured by Nippon Polyurethane Industry Co., Ltd.) as a crosslinking agent were added. Except for the above, in the same manner as in Example 2, the acrylic pressure-sensitive adhesive composition and The surface protection film was produced.

(Comparative Example 8)
(Preparation of coating agent)
In a water-alcohol solvent, an antistatic agent composed of a cationic polymer (trade name “Bondip-P main agent”, manufactured by Konishi Co., Ltd.) and an epoxy resin (trade name “Bondip-P curing agent”) ", Manufactured by Konishi Co., Ltd.) with a mass ratio of 100: 46.7 on NV basis. By applying this solution to the corona-treated surface (first surface) of the same PET film as used in Example 1 at 0.06 g / m ² on an NV basis and drying, a topcoat layer having a thickness of 80 nm is dried. Formed. Next, a long-chain alkyl carbamate-based release treatment agent (trade name “Pyroyl 1010”, manufactured by Yushi Kogyo Co., Ltd.) is applied to the surface of the top coat layer so as to be 0.02 g / m ² on an NV basis. By attaching and drying, the top coat layer was given slipperiness to obtain a substrate with a top coat.
(Preparation of adhesive composition)
The acrylic polymer solution (40% by weight) obtained by the same production method as in Example 1 was diluted to 20% by weight with ethyl acetate, and the anionic surfactant was added to 100 parts by weight of the solid content in the solution. Polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate (trade name “Aqualon HS-10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.3 parts by weight, hexamethylene diisocyanate isocyanurate (trade name “Coronate HX”) 4 parts by weight, manufactured by Nippon Polyurethane Industry Co., Ltd., 0.03 part by weight of dibutyltin dilaurate (trade name “OL-1”, manufactured by Tokyo Fine Chemical Co., Ltd., 0.5 wt% ethyl acetate solution) as a crosslinking catalyst, and as a crosslinking retarder Acrylic adhesive composition in which 3 parts by weight of acetylacetone is added to the total amount of solvent and mixed and stirred. It was prepared.
(Production of surface protective film)
A surface protective film was obtained in the same manner as in Example 1 using the base material with a top coat and the acrylic pressure-sensitive adhesive composition.

(Evaluation)
About the surface protection film obtained by said Example and comparative example, whitening resistance, surface protection film external appearance, solvent resistance, back surface peeling strength, water contact angle, acrylic tape No. The adhesive strength of 31B, the wettability of the interlayer filler, and the adhesion of the interlayer filler were evaluated by the above methods. The evaluation results are shown in Tables 1 and 2.

1: Surface protective film 1A: Front surface (rear surface)
12: Base material 12A: First surface (back surface)
12B: Second side (front side)
14: Topcoat layer 20: Acrylic adhesive layer 20A: Surface (adhesive surface)
30: Release liner 50: Substrate 60: Adhesive tape (pickup tape)
62: Base material 64: Adhesive layer 114: Topcoat layer 120A: Adhesive surface 130: Double-sided adhesive tape 132: Stainless steel plate 160: Adhesive tape 162: Adhesive 162A: Adhesive surface

Claims (7)

A substrate having a first surface and a second surface;
A topcoat layer provided on the first surface side of the substrate;
An acrylic pressure-sensitive adhesive layer provided on the second surface side of the substrate;
A surface protective film comprising:
The top coat layer includes a wax as a slip agent and a polyester resin as a binder,
The wax is an ester of a higher fatty acid and a higher alcohol;
A surface protective film, wherein the acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a base polymer and has the following properties (1) and (2).
(1) After the surface of the acrylic pressure-sensitive adhesive layer of the surface protective film is attached to the surface of the adherend X below at a temperature of 23 ° C. and a humidity of 30%, the temperature is 50 ° C., the pressure is 5 atm, and the time is 15 minutes. The water contact angle A on the surface of the adherend X after the surface protective film was peeled off after leaving the surface protective film for 12 hours at a temperature of 23 ° C. and a humidity of 30% was 70 ° or less (2) After the surface of the surface of the adherend X was adhered to the surface of the adherend X at a temperature of 23 ° C. and a humidity of 30%, it was autoclaved at a temperature of 50 ° C., a pressure of 5 atm, and a time of 15 minutes. Acrylic tape (manufactured by Nitto Denko Corp., product number No. 31B, substrate thickness) on the surface of the adherend X after being adhered and allowed to stand at a temperature of 23 ° C. and a humidity of 30% for 12 hours and peeling off the surface protective film. 25 μm) adhesive strength (peeling Separation angle 180 °, pulling speed 300 mm / min) is the adhesive force (peeling angle 180 °, pulling speed 300 mm) of acrylic tape (Nitto Denko Corporation, product number No. 31B, substrate thickness 25 μm) on the following adherend X surface. Adherent X higher than (min./min): hard coat film having a water contact angle of 80 to 100 °   The surface protective film according to claim 1, wherein the substrate is a polyethylene terephthalate film or a polyethylene naphthalate film.   The surface protection film according to claim 1, wherein the topcoat layer further contains an antistatic component.   The surface protection film according to claim 1, wherein the acrylic pressure-sensitive adhesive layer contains an anionic surfactant.   The surface protection film according to claim 4, wherein the content of the anionic surfactant is 0.2 to 4 parts by weight with respect to 100 parts by weight of the acrylic polymer.   It is a surface protection film for optical members, The surface protection film of any one of Claims 1-5.   The optical member containing the surface protection film of any one of Claims 1-6.

Images