TWI568585B - Surface protection film and optical component attached with the same - Google Patents

Description

Surface protection film and optical component to which the surface protection film is attached

The present invention relates to a surface protective film which is bonded to a surface of an optical component such as a polarizing plate, a phase difference plate, or a lens film for a display (hereinafter sometimes referred to as "optical film"). More specifically, the present invention provides a surface protective film having less contamination to an adherend, an excellent surface resist film having excellent anti-peeling performance without deterioration over time, and an optical component to which the surface protective film is bonded .

When manufacturing and transporting optical films such as a polarizing plate, a retardation film, a lens film for a display, an antireflection film, a hard coat film, and a transparent conductive film for a touch panel, and an optical product such as a display using the same, Surface contamination and scratching in the subsequent steps are prevented by bonding the surface protective film to the surface of the optical film. In order to save labor and time after peeling the surface protective film and to improve work efficiency, the surface film may be bonded to the optical film for visual inspection of the optical film as a product. Direct implementation in the state.

Conventionally, in order to prevent the adhesion of scratches and dirt in the manufacturing process of an optical product, a surface protective film in which a binder layer is provided on one surface of a base film is generally used. The surface protective film is pasted by a micro-adhesive layer of adhesive It is combined with an optical film. The reason why the adhesive layer is set to the micro-adhesive force is that it can be easily peeled off in order to remove the used surface protective film from the surface of the optical film, and to prevent adhesion of the adhesive and remain as an adherend. A phenomenon on the optical film of the product (so-called prevention of the occurrence of adhesive residue).

In the production process of the liquid crystal display panel, the peeling static voltage generated when the surface protective film attached to the optical film is peeled off and removed is destroyed, and the circuit such as the driving IC for controlling the display screen of the liquid crystal display is destroyed. The orientation of the parts, as well as the liquid crystal molecules, can be damaged, although the number of occurrences of these phenomena is small but also occurs.

In addition, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material tends to decrease, and accordingly, the breakdown voltage of the driving IC tends to decrease. Recently, it has been required to control the peeling static voltage in the range of +0.7 kV to -0.7 kV.

In addition, in recent years, with the spread of 3D displays (stereoscopic displays), FPR (Film Patterned Retarder) films are bonded to the surface of an optical film such as a polarizing plate. After peeling off the surface protection film bonded to the surface of the optical film, such as a polarizing plate, the FPR film is bonded. However, when the surface of the optical film such as a polarizing plate is contaminated by a binder or an antistatic agent used in the surface protective film, there is a problem that it is difficult to adhere the FPR film. Therefore, the surface protective film used for this use is required to have less contamination of the adherend.

On the other hand, in some liquid crystal panel manufacturers, as a method of evaluating the contamination of the adherend by the surface protective film, a method of peeling off the surface protective film bonded to the optical film such as a polarizing plate is first employed. , re-bonding in a state in which air bubbles are mixed, and the conditions of the reattached object are in predetermined conditions The heat treatment was performed, and then the surface protective film was peeled off and the surface of the adherend was observed. In this evaluation method, even if the surface contamination of the adherend is minute, if there is a difference in the surface contamination of the adherend between the portion where the bubble is mixed and the contact of the surface protective film, Bubble marks (sometimes referred to as "bubble stains") remain. Therefore, as a method of evaluating the contamination of the surface of the adherend, it is a very strict evaluation method. In recent years, according to the result of the determination by such a strict evaluation method, a surface protective film which has no problem in surface contamination of the adherend is required.

In order to prevent defects caused by high peeling static voltage when the surface protective film is peeled off from the optical film as the adherend, a surface protective film using an antistatic agent for reducing the peeling static voltage has been proposed. Adhesive layer.

For example, Patent Document 1 discloses a surface protective film using a binder composed of an alkyltrimethylammonium salt, a hydroxyl group-containing acrylic polymer, or a polyisocyanate.

Further, Patent Document 2 discloses a binder composition composed of an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and a binder sheet using the composition.

Further, Patent Document 3 discloses a binder composition composed of an acrylic polymer, a polyether polyol compound, an alkali metal salt treated with an anion-adsorbing compound, and surface protection using the composition. membrane.

Further, Patent Document 4 discloses a binder composition comprising an ionic liquid, an alkali metal salt, a polymer having a glass transition temperature of 0 ° C or lower, and a surface protective film using the composition.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. 2005-131957

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-330464

Patent Document 3: Japanese Laid-Open Patent Publication No. 2005-314476

Patent Document 4: Japanese Laid-Open Patent Publication No. 2006-152235

In the above Patent Documents 1 to 4, an antistatic agent is added to the inside of the binder layer. However, the thicker the thickness of the adhesive layer, and the more the amount of movement of the antistatic agent from the adhesive layer to the adherend adhered to the surface protective film, as time passes after adhering to the adherend. When the amount of the antistatic agent moving to the adherend is increased, the appearance quality of the optical film as the adherend is lowered. Alternatively, when the FPR film is bonded, the adhesiveness of the FPR film may be lowered.

In order to reduce the temporal change of the antistatic agent which moves from the adhesive layer to the adherend at this time, if the thickness of the adhesive layer is lowered, other problems may occur. For example, when an optical film having irregularities on the surface such as a polarizing plate after the anti-glare treatment is applied to prevent glare, the adhesive layer cannot meet the irregularities on the surface of the optical film to mix air bubbles, or the optical film and The bonding area of the binder is reduced to lower the bonding force, and there is a problem that the surface protective film is separated or peeled off during use.

Therefore, there is a need for a surface protective film for use in an optical film which can be used for an optical film having irregularities on the surface, which has little contamination to the adherend and no change with time on the contamination of the adherend. And, also A surface protective film capable of suppressing peeling static voltage when the surface protective film is peeled off from the adherend.

The inventors of the present invention have carefully studied this subject.

In order to reduce the contamination of the adherend and also reduce the temporal change of the contamination, it is necessary to reduce the amount of the antistatic agent component which is presumed to be contaminated by the adherend. However, when the amount of the antistatic agent component is lowered, the peeling static voltage when the surface protective film is peeled off from the adherend becomes high. Then, the inventors of the present invention have studied a method of suppressing the peeling static voltage when the surface protective film is peeled off from the adherend without reducing the absolute amount of the antistatic agent component.

As a result, it was found that an antistatic agent is not added to the binder composition and mixed to form a binder layer, but the binder composition is applied and dried to laminate the binder layer, and an appropriate amount is applied to the surface of the binder layer. The antistatic component can suppress the peeling static voltage when the surface protective film is peeled off from the optical film as the adherend, and the present invention has been completed based on the above findings.

The present invention has been made in view of the above circumstances, and it is an object of the invention to provide an optical film having irregularities on its surface, which is less likely to be used for contamination of an adherend, and which is less polluting to the adherend. A surface protective film which changes in progress and further has an excellent surface resisting film which is resistant to peeling deterioration and has an anti-peeling electrostatic property, and an optical component using the surface protective film.

In order to solve the above problems, the technical concept of the surface protective film of the present invention is to apply an appropriate amount of an antistatic agent to the surface of the adhesive layer after the adhesive composition is applied and dried to laminate the adhesive layer. Suppress The contamination to the adherend is low, and the peeling static voltage when peeling off from the optical film as the adherend can be suppressed.

In order to solve the above problems, the present invention provides a surface protective film in which a binder layer is formed on one surface of a base film composed of a resin having transparency, and a release agent is bonded to the binder layer. a surface protective film of a release film in which a release agent layer is formed on one surface of a resin film, and the release agent layer contains a release agent containing dimethyl polysiloxane as a main component and The antistatic agent which does not react with the release agent, and the antistatic agent component is transferred from the release film to the surface of the adhesive layer, whereby the peeling static voltage when the adhesive layer is peeled off from the adherend can be reduced.

Further, it is preferred that the antistatic agent is an ionic compound having a melting point of 30 to 80 °C.

Further, it is preferred that the binder layer be formed by crosslinking a (meth) acrylate copolymer.

Moreover, it is preferable that the peeling force at the time of peeling the said peeling film from the said adhesive agent layer is 0.2 N / 50 mm or less.

Further, the present invention provides an optical component to which the above surface protective film is bonded.

The surface protective film of the present invention has less contamination of the adherend, and the low contamination of the adherend does not change over time. In addition, the surface protective film of the present invention can be used even if the adherend is an optical film having irregularities on the surface of an AG polarizing plate or the like. Further, according to the present invention, it is possible to provide a peeling which occurs when peeling off from an optical film as an adherend A surface protective film having a static voltage and excellent excellent anti-peeling electrostatic properties without deterioration with time, and an optical component using the surface protective film.

According to the surface protection film of the present invention, the surface of the optical film can be reliably protected, so that the production efficiency can be improved and the yield can be improved.

1‧‧‧Base film

2‧‧‧Binder layer

3‧‧‧ resin film

4‧‧‧ Stripper layer

5‧‧‧Release film

7‧‧‧Antistatic agent

8‧‧‧Adhered body (optical parts)

10‧‧‧Surface protection film

11‧‧‧Surface protection film after peeling off the film

20‧‧‧Optical parts with surface protection film

Fig. 1 is a cross-sectional view showing the concept of a surface protective film of the present invention.

Fig. 2 is a cross-sectional view showing a state in which a release film is peeled off from the surface protection film of the present invention.

Fig. 3 is a cross-sectional view showing an embodiment of an optical component of the present invention.

Hereinafter, the present invention will be described in detail based on embodiments.

Fig. 1 is a cross-sectional view showing the concept of a surface protective film of the present invention. In the surface protection film 10, the adhesive layer 2 is formed on the surface of one surface of the transparent base film 1. A release film 5 is formed on the surface of the adhesive layer 2, and the release film 5 is formed by forming a release agent layer 4 on the surface of the resin film 3.

As the base film 1 used in the surface protective film 10 of the present invention, a base film composed of a resin having transparency and flexibility is used. Thereby, the visual inspection of the optical component can be performed in a state where the surface protective film is bonded to the optical component as the adherend. As the film made of the transparent resin used as the base film 1, polyethylene terephthalate, polyethylene naphthalate, and polyethylene isophthalate are preferably used. Polyester film such as polyethylene isophthalate) or polybutylene terephthalate. As the film, as long as it has a desired strength and is optically adaptable, other resin structures may be used in addition to the polyester film. The film formed. The base film 1 may be an unstretched film or a film subjected to uniaxial stretching or biaxial stretching. Further, the stretching ratio of the stretched film and the orientation angle in the axial direction formed by the crystallization of the stretched film may be controlled to specific values.

The thickness of the base film 1 used in the surface protection film 10 of the present invention is not particularly limited, and is, for example, preferably a thickness of about 12 to 100 μm ; and a thickness of about 20 to 50 μm. Easy to operate, so it is more desirable.

Further, if necessary, an antifouling layer for preventing surface contamination, an antistatic layer, and a hard coat layer for preventing scratching may be provided on the surface of the base film 1 opposite to the surface on which the adhesive layer 2 is formed. . Further, on the surface of the base film 1, an easy adhesion treatment such as surface modification by corona discharge or application of a primer may be performed.

Further, the adhesive layer 2 used in the surface protective film 10 of the present invention is a binder layer which can be easily peeled off after being used and adhered to the surface of the adherend, and which is difficult to contaminate the adherend. However, it is not particularly limited, but a binder layer obtained by crosslinking a (meth) acrylate copolymer is usually used in consideration of durability and the like after bonding on an optical film.

The (meth) acrylate copolymer may, for example, be a copolymer obtained by copolymerizing a main monomer with a comonomer, a functional monomer, or a polyoxyalkylene-containing monomer, wherein the main single Examples of the compound include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isodecyl acrylate, and the like; examples of the comonomer include acrylonitrile, vinyl acetate, methyl methacrylate, and acrylic acid. Ethyl ester or the like; the functional monomer may, for example, be acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, N-methylol methacrylamide or the like; The oxyalkylene monomer can be exemplified by methoxypolyethylene glycol. Methacrylate and the like. In the (meth) acrylate copolymer, the main monomer and other monomers may be (meth) acrylate, or may be a monomer other than the main monomer, and one or two or more (meth) may be contained. A monomer other than acrylate. The monomer other than the main monomer can be selected from the above comonomer, a functional monomer, a polyoxyalkylene group-containing monomer, and the like, and is not particularly limited.

The curing agent to be added to the binder layer 2 may, for example, be an isocyanate compound, an epoxy compound, a melamine compound, a metal chelate compound or the like as a crosslinking agent for crosslinking the (meth) acrylate copolymer. Further, examples of the tackifier include rosins, coumarone-oximes, terpenes, petroleums, and phenols.

The thickness of the adhesive layer 2 used in the surface protection film 10 of the present invention is not particularly limited, and is, for example, preferably about 5 to 40 μm , more preferably about 10 to 30 μm . In addition, when the peeling strength (bonding force) of the surface protective film to the surface of the adherend is 0.03 to 0.3 N/25 mm, and the adhesive layer 2 having a micro-adhesive force is peeled off, when the surface protective film is peeled off from the adherend It is excellent in operability and therefore ideal. In addition, from the viewpoint of excellent workability when the release film 5 is peeled off from the surface protective film 10, the peeling force when the release film 5 is peeled off from the adhesive layer 2 is preferably 0.2 N/50 mm or less.

Further, in the release film 5 used in the surface protection film 10 of the present invention, the release agent layer 4 is formed on one surface of the resin film 3, and the release agent layer 4 contains dimethyl polysiloxane as a dimethyl group. A release agent of a main component and an antistatic agent that does not react with the release agent.

Examples of the resin film 3 include a polyester film, a polyamide film, a polyethylene film, a polypropylene film, and a polyimide film, which are excellent in transparency and low in price. From the standpoint of low cost, a polyester film is particularly preferred. The resin film may be either an unstretched film or a uniaxially stretched film or a biaxially stretched film. Further, the stretching ratio of the stretched film and the orientation angle in the axial direction formed by the crystallization of the stretched film may be controlled to specific values.

The thickness of the resin film 3 is not particularly limited, and is, for example, preferably a thickness of about 12 to 100 μm ; and a thickness of about 20 to 50 μm is easy to handle, and therefore it is more preferable.

Further, on the surface of the resin film 3, an easy adhesion treatment such as surface modification by corona discharge or application of a primer may be carried out as needed.

The release agent containing dimethyl polysiloxane as a main component constituting the release agent layer 4 may be a known polyoxane such as an addition reaction type, a condensation reaction type, a cationic polymerization type or a radical polymerization type. Alkane stripper. As a commercially available product of an addition reaction type polyoxyalkylene type release agent, for example, KS-776A, KS-847T, KS-779H, KS-837, KS-778, and KS-830 (Shin-Etsu Chemical Industry) (manufactured by the company); SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (Dow Corning Toray) Co., Ltd.))). Examples of the commercially available product of the condensation reaction type include SRX-290 and SYLOFF-23 (manufactured by Dow Corning Toray Co., Ltd.). Examples of the commercially available product of the cationic polymerization type include TPR-6501, TPR-6500, UV9300, UV9315, UV9430 (manufactured by Momentive Performance Materials Inc.), and X62-7622 (Shin-Etsu Chemical Industry). (share) company manufacturing) and so on. Examples of the commercially available product of the radical polymerization type include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.).

As the antistatic agent constituting the release agent layer 4, it is preferred that the dispersant solution containing dimethyl polysiloxane as a main component has good dispersibility and does not inhibit dimethylpolysiloxane as a main component. A cured antistatic agent for the release agent. Further, in order to allow the antistatic agent to be transferred from the release agent layer 4 to the surface of the binder layer 2 to impart an antistatic effect to the binder layer, it is preferred not to be detached with dimethylpolysiloxane as a main component. An antistatic agent that reacts with the agent. As such an antistatic agent, an ionic compound having a melting point of 30 to 80 ° C is preferred.

The ionic compound having a melting point of 30 to 80 ° C is an ionic compound having a cation and an anion, and examples of the cation include a pyridinium cation, an imidazolium cation, a pyrimidine cation, a pyrazolium cation, a pyrrolidinium cation, and an ammonium cation. The nitrogen-containing phosphonium cation, or a phosphonium cation, a sulfonium cation, etc.; the anion is hexafluorophosphate (PF ₆ ^- ), thiocyanate (SCN ^- ), alkyl benzene sulfonate (RC ₆ H ₄ SO ₃ ^- ), a compound of an inorganic or organic anion such as perchlorate (ClO ₄ ^- ) or tetrafluoroborate (BF ₄ ^- ). A compound having a melting point of 30 to 80 ° C can be obtained by selecting the chain length of the alkyl group, the position and number of the substituents, and the like. Preferably, the cation is a 4-stage nitrogen sulfonium cation, and a 4-stage pyridinium cation such as 1-alkylpyridinium (having a substituent or a substituent at the carbon atom of 2 to 6) may be mentioned. a 4-stage imidazolium cation such as a 3-dialkylimidazolium (a carbon atom at the 2, 4 or 5 position may have a substituent or a substituent), or a 4-stage ammonium cation such as a tetraalkylammonium.

The amount of the antistatic agent added to the release agent containing dimethylpolysiloxane as a main component differs depending on the type of the antistatic agent and the degree of affinity with the release agent. The amount of antistatic agent added is only considered to be peeled off from the adherend The peeling static voltage required for the surface protective film, the contamination to the adherend, the bonding characteristics, and the like may be set.

The release agent layer 4 may be a release agent layer 4 formed by a mixture of a release agent containing dimethylpolysiloxane as a main component and an antistatic agent which does not react with the release agent. The method of mixing the release agent and the antistatic agent containing dimethylpolysiloxane as a main component is not particularly limited. Any one of the following mixing methods may be employed: a method in which an antistatic agent is added to a release agent containing dimethyl polysiloxane as a main component, and a catalyst for curing the release agent is added and mixed; After the solvent is diluted with a release agent containing dimethyl polysiloxane as a main component, an antistatic agent and a catalyst for curing the release agent are added and mixed; and peeling with polydimethylpolysiloxane as a main component is previously performed. After the agent is diluted in an organic solvent, a catalyst is added and mixed, and then an antistatic agent is added and mixed. Further, if necessary, a material having an antistatic effect such as a binder accelerator such as a decane coupling agent or a compound containing a polyoxyalkylene group may be added.

The mixing ratio of the release agent and the antistatic agent containing dimethyl polysiloxane as a main component is not particularly limited, but is a solid relative to a release agent containing dimethyl polyoxyalkylene as a main component. The component 100 is preferably a ratio of the antistatic agent in a solid content of about 5 to 100. When the amount of the antistatic agent added in a solid content is less than 5 with respect to the solid content 100 of the release agent containing dimethyl polysiloxane as a main component, the amount of the antistatic agent transferred to the surface of the binder layer It is also less, and it is difficult to make the adhesive layer function as an antistatic. In addition, the solid content of the antistatic agent in terms of solid content is more than 100 in the solid content 100 of the release agent containing dimethyl polysiloxane as a main component. In the proportion, the release agent containing dimethylpolysiloxane as a main component together with the antistatic agent is also transferred to the surface of the adhesive layer, and thus the adhesive property of the adhesive layer may be lowered.

In the present invention, the method of forming the adhesive layer 2 on the base film 1 of the surface protective film 10 and the method of bonding the release film 5 can be carried out by a known method, and are not particularly limited. Specifically, (1) a method in which a resin composition for forming the binder layer 2 is applied onto one surface of the base film 1 and dried to form a binder layer, and then the release film 5 is bonded; (2) A method in which the resin composition for forming the binder layer 2 is applied onto the surface of the release film 5 and dried to form a binder layer, and then the base film 1 is bonded. Any of these methods can be employed.

Further, when the adhesive layer 2 is formed on the surface of the base film 1, it can be carried out by a known method. Specifically, a known coating method such as reverse coating, comma coating, gravure coating, slit extrusion coating, Mayer bar coating, or air knife coating can be used.

Further, similarly, when the release agent layer 4 is formed on the resin film 3, it can be carried out by a known method. Specifically, a known coating method such as gravure coating, Mylar rod coating, or air knife coating can be employed.

The surface protective film 10 of the present invention having the above-described configuration preferably has a surface potential of from +0.7 kV to -0.7 kV when peeled off from the optical film as the adherend. Further, it is more preferable that the surface potential is +0.5 kV to -0.5 kV, and particularly preferably the surface potential is +0.1 kV to -0.1 kV. This surface potential can be adjusted by changing the kind, addition amount, and the like of the antistatic agent contained in the release agent layer.

Figure 2 is a view showing peeling off the release film from the surface protective film of the present invention A sectional view of the state.

By peeling off the release film 5 from the surface protection film 10 shown in FIG. 1, a part of the antistatic agent (reference numeral 7) contained in the release agent layer 4 of the release film 5 is transferred (attached) to the surface. The surface of the adhesive layer 2 of the protective film 10. Therefore, in Fig. 2, the antistatic agent transferred to the surface of the adhesive layer 2 of the surface protective film is schematically indicated by the spot of the reference numeral 7. By the component of the antistatic agent 7 being transferred from the release film 5 to the surface of the adhesive layer 2, the peeling static voltage when the adhesive layer 2 is peeled off from the adherend can be reduced. Further, the peeling static voltage when the adhesive layer is peeled off from the adherend can be measured by a known method. For example, after the surface protective film is bonded to the adherend such as a polarizing plate, a high-speed peeling tester (manufactured by TESTER Sangyo Co., Ltd.) is used at a peeling speed of 40 m per minute. While peeling off the surface protective film, the surface potential of the surface of the adherend was measured every 10 ms using a surface potentiometer (manufactured by Keyence Corporation), and the maximum value of the absolute value of the surface potential at this time was taken as the peeling off. The static voltage (kV) was used for the measurement.

In the surface protective film of the present invention, when the surface protective film 11 in the state in which the release film is peeled off as shown in FIG. 2 is attached to the adherend, the antistatic agent transferred to the surface of the adhesive layer 2 is applied. Contact with the surface of the adherend. By this operation, it is possible to suppress the peeling static voltage when the surface protective film is peeled off again from the adherend.

Fig. 3 is a cross-sectional view showing an embodiment of an optical component of the present invention.

In the state where the release film 5 is peeled off from the surface protection film 10 of the present invention and the adhesive layer 2 is exposed, the adhesive layer 2 is bonded to the optical component 8 as an adherend.

That is, the optical component 20 to which the surface protection film 10 of the present invention is bonded is shown in FIG. Examples of the optical component include an optical film such as a polarizing plate, a phase difference plate, a lens film, a polarizing plate which also serves as a phase difference plate, and a polarizing plate which also serves as a lens film. Such an optical component is used as a component of a liquid crystal display device such as a liquid crystal display panel or an optical system device of various measuring instruments. In addition, examples of the optical component include an optical film such as an antireflection film, a hard coat film, and a transparent conductive film for a touch panel.

According to the optical component of the present invention, when the surface protective film 10 is peeled off from the optical component (optical film) as the adherend, the peeling static voltage can be sufficiently suppressed to a low level. Therefore, there is no fear that the circuit components such as the driver IC, the TFT element, and the gate line driver circuit are destroyed, and the production efficiency in the steps of manufacturing the liquid crystal display panel and the like can be improved, and the reliability of the production steps can be ensured.

[Examples]

Hereinafter, the present invention will be further described by way of examples.

(Example 1)

(Manufacture of surface protective film)

5 parts by weight of an addition reaction type polyoxyalkylene (product name: SRX-345, manufactured by Dow Corning Toray Co., Ltd.), 0.75 parts by weight of N-butyl-4-methylpyridinium hexafluoride Phosphate, 95 parts by weight of a mixed solvent of toluene and ethyl acetate of 1:1, and 0.05 part by weight of a platinum catalyst (product name: SRX-212, manufactured by Dow Corning Toray Co., Ltd.) are mixed and carried out. The coating for forming the release agent layer of Example 1 was prepared by stirring and mixing. The coating material for forming the release agent layer of Example 1 was applied to a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 0.2 μm after drying using a Myrtle rod. The surface was dried in a hot air loop oven at 120 ° C for 1 minute to obtain a release film of Example 1. On the other hand, 30 parts by weight of an acrylate copolymer having a weight average molecular weight of 470,000 obtained by copolymerizing 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate in a weight ratio of 100:4 was dissolved in A binder (30% solids ethyl acetate solution) was obtained in 70 parts by weight of ethyl acetate, and 1.2 parts by weight of an HDI-based curing agent (product name: Coronate) was added to 100 parts by weight of the binder. HX, manufactured by Nippon Polyurethane Industry Co., Ltd., and mixed to form an application liquid, and the application liquid is applied to a thickness of 20 μm after drying. The surface of a 38 μm polyethylene terephthalate film was then dried by a hot air loop oven at 100 ° C for 2 minutes to form a binder layer. Then, a release agent layer (polysiloxane treatment surface) of the release film of Example 1 produced above was bonded to the surface of the adhesive layer. The obtained bonded film was kept at 40 ° C for 5 days to cure the adhesive, and the surface protective film of Example 1 was obtained.

(Example 2)

The surface protective film of Example 2 was obtained in the same manner as in Example 1 except that the coating material for forming the release agent layer of Example 1 was applied so as to have a thickness of 0.1 μm after drying.

(Example 3)

Except that SRX-211 (product name) manufactured by Dow Corning Toray Co., Ltd. was used as the addition reaction type polyoxane of Example 1, the same operation as in Example 1 was carried out, and Example 3 was obtained. Surface protection film.

(Comparative Example 1)

5 parts by weight of an addition reaction type polyoxyalkylene (product name: SRX-345, manufactured by Dow Corning Toray Co., Ltd.), 95 parts by weight of a mixed solvent of toluene and ethyl acetate of 1:1, 0.05 part by weight of a platinum catalyst (product name: SRX-212, manufactured by Dow Corning Toray Co., Ltd.) was mixed and stirred to prepare a coating material for forming the release agent layer of Comparative Example 1. The coating material for forming the release agent layer of Comparative Example 1 was applied to a polyethylene terephthalate film having a thickness of 38 μm so as to have a thickness of 0.2 μm after drying using a Myrtle rod. The surface was dried in a hot air loop type oven at 120 ° C for 1 minute to obtain a release film of Comparative Example 1. On the other hand, N-butyl-4-methylpyridinium hexafluorophosphate 3 was added and mixed with respect to 100 parts by weight of the binder of Example 1 (ethyl acetate solution having a solid content of 30%). 1.2 parts by weight of an HDI-based curing agent (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) was used to form an application liquid, and the application liquid was applied so as to have a thickness of 20 μm after drying. The surface of the polyethylene terephthalate film having a thickness of 38 μm was then dried by a hot air loop oven at 100 ° C for 2 minutes to form a binder layer. Then, a release agent layer (polyoxane-treated surface) of the release film of Comparative Example 1 produced above was bonded to the surface of the adhesive layer. The obtained bonded film was kept at 40 ° C for 5 days to cure the adhesive, and the surface protective film of Comparative Example 1 was obtained.

(Comparative Example 2)

A surface protective film of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that 0.1 part by weight of N-butyl-4-methylpyridinium hexafluorophosphate was used.

(Example 4)

2-ethylhexyl acrylate, butyl acrylate and 2-hydroxyethyl acrylate 30 parts by weight of an acrylate copolymer having a weight average molecular weight of 480,000 by weighting at a weight ratio of 60:40:4, dissolved in 70 parts by weight of ethyl acetate to form a binder (acetic acid having a solid content of 30%) Ethyl ester solution), adding and mixing 1.2 parts by weight of an HDI-based curing agent (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) with respect to 100 parts by weight of the binder to obtain an application liquid, using the application liquid A surface protective film of Example 4 was obtained in the same manner as in Example 1 except that the application liquid of Example 1 was used instead.

(Example 5)

The weight average molecular weight of 2-ethylhexyl acrylate, methoxypolyethylene glycol (400) methacrylate and 2-hydroxyethyl acrylate copolymerized at a weight ratio of 90:10:4 is 380,000. 30 parts by weight of the (meth) acrylate copolymer, dissolved in 70 parts by weight of ethyl acetate to form a binder (ethyl acetate solution having a solid content of 30%), and added to 100 parts by weight of the binder And adding 1.2 parts by weight of an HDI-based curing agent (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) to obtain an application liquid, and using the application liquid instead of the application liquid of Example 1, in addition to the implementation In the same manner as in Example 1, the surface protective film of Example 5 was obtained.

(Example 6)

30 parts by weight of an acrylate copolymer having a weight average molecular weight of 520,000 and a copolymer of 2-ethylhexyl acrylate and acrylic acid in a weight ratio of 100:4, dissolved in 70 parts by weight of ethyl acetate to form a binder (A solution of ethyl acetate having a solid content of 30%), and 1.0 part by weight of an epoxy-based curing agent (product name: TETRAD-C, Mitsubishi Gas Chemical Co., Ltd.) was added and mixed with 100 parts by weight of the binder. (made by Mitsubishi Gas Chemical Company Inc.) A surface protective film of Example 6 was obtained in the same manner as in Example 1 except that the application liquid was used instead of the application liquid of Example 1.

Next, the method and result of the evaluation test are shown.

<Method for Measuring Peel Force of Release Film>

A sample of the surface protective film was cut in a size of 50 mm in width and 150 mm in length. In a test environment of 23 ° C × 50% RH, the release film was peeled off in a 180° direction at a peeling speed of 300 mm/min using a tensile tester, and the strength at that time was measured, and this was used as a peeling force of the release film (N). /50mm).

<Method for Measuring the Bonding Force of Surface Protective Film>

An anti-glare low-reflection polarizing plate (AG-LR polarizing plate) was bonded to the surface of the glass plate by a laminating machine. Then, the surface protective film cut into a width of 25 mm was bonded to the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 1 day. Then, the surface protective film was peeled off in a 180° direction at a peeling speed of 300 mm/min using a tensile tester, and the strength at this time was measured and used as a bonding force (N/25 mm).

<Method for Measuring Peeling Static Voltage of Surface Protective Film>

An anti-glare low-reflection polarizing plate (AG-LR polarizing plate) was bonded to the surface of the glass plate by a laminating machine. Then, the surface protective film cut into a width of 25 mm was bonded to the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 1 day. Then, while peeling off the surface protective film at a peeling speed of 40 m per minute using a high-speed peeling tester (manufactured by TESTER Sangyo Co., Ltd.), a surface potentiometer was used (Keyence) The company (manufactured by Keyence Corporation) measures the surface potential of the surface of the polarizing plate every 10 ms, and the maximum value of the absolute value of the surface potential at this time is taken as the peeling static voltage (kV).

<Method for Confirming Surface Contamination of Surface Protective Film>

An anti-glare low-reflection polarizing plate (AG-LR polarizing plate) was bonded to the surface of the glass plate by a laminating machine. Then, the surface protective film cut into a width of 25 mm was attached to the surface of the polarizing plate, and then stored in a test environment of 23 ° C × 50% RH for 3 days and 30 days. Then, the surface protective film was peeled off, and the contamination of the surface of the polarizing plate was observed by visual observation. As a criterion for determining the surface contamination property, it was judged as (○) when there was no contamination transition on the polarizing plate, and it was judged as (×) when it was confirmed that there was contamination transition on the polarizing plate.

The surface protective films of the obtained Examples 1 to 6 and Comparative Examples 1 and 2 were measured, and the measurement results are shown in Tables 1 and 2. Wherein "2EHA" means 2-ethylhexyl acrylate, "HEA" means 2-hydroxyethyl acrylate, "BA" means butyl acrylate, and "#400G" is methoxy ethoxy polyethylene glycol ( 400) Methacrylate, "AA" means acrylic acid, and "AS agent" means N-butyl-4-methylpyridinium hexafluorophosphate. The composition of the binder layer and the release agent layer is expressed in parts by weight in such a manner that the total amount of the binder or the total amount of the coating material for forming the release agent layer is about 100 parts by weight, respectively.

From the measurement results shown in Tables 1 and 2, the following can be seen.

The surface protective films of Examples 1 to 6 of the present invention have a suitable bonding force, do not contaminate the surface of the adherend, and have a low peeling static voltage when the surface protective film is peeled off from the adherend.

On the other hand, in the surface protective film of Comparative Example 1 in which the antistatic agent was added to the adhesive layer, the peeling static voltage was good when the surface protective film was peeled off from the adherend, but the adherend was peeled off after peeling. More pollution. Further, in Comparative Example 2 in which the amount of the antistatic agent was reduced, the contamination to the adherend was improved, but the peeling static voltage was high when the surface protective film was peeled off from the adherend.

In other words, according to Comparative Examples 1 and 2 in which the antistatic agent was mixed in the binder, it was difficult to achieve both a decrease in the peeling static voltage and an improvement in the staining property of the adherend. On the other hand, in Examples 1 to 6 in which the antistatic agent was added to the release agent layer and then transferred to the surface of the adhesive layer, the effect of reducing the peeling static voltage with a small addition amount was obtained, and thus the adhered body was obtained. There is no pollution, and the anti-peeling electrostatic properties are also good. Surface protection film.

[Industry Utilization]

The surface protective film of the present invention can be applied to an optical film such as a polarizing plate, a retardation film, or a lens film, and can be bonded to the optical component or the like in a production step of various optical components or the like. Used to protect its surface. Further, the surface protective film of the present invention can reduce the amount of static electricity generated when peeling off from the adherend, and the deterioration of the anti-peeling electrostatic property over time and the contamination of the adherend are small, and the yield of the production step can be improved. Industrial use is of great value.

1‧‧‧Base film

2‧‧‧Binder layer

3‧‧‧ resin film

4‧‧‧ Stripper layer

5‧‧‧Release film

7‧‧‧Antistatic agent

10‧‧‧Surface protection film

Claims (5)

A surface protective film which is a surface protective film in which a binder layer is formed on one surface of a base film made of a resin having transparency, wherein a release film having a release agent layer is bonded to the adhesive layer The release agent layer contains a release agent and an antistatic agent, and the antistatic agent having an ionic compound having a melting point of 30 to 80 ° C which can be transferred from the release agent layer is provided only on the surface of the release agent layer. The surface protective film of claim 1, wherein the adhesive layer is formed by crosslinking a (meth) acrylate copolymer. The surface protective film of claim 1 or 2, wherein the release agent contains dimethyl polysiloxane as a main component. The surface protection film of the first or second aspect of the invention, wherein the anti-fouling layer, the antistatic layer, which is selected from the surface contamination prevention surface, is formed on a surface of the base film opposite to the surface on which the adhesive layer is formed. One or more layers of the group consisting of hard coat layers that prevent scratching. An optical component to which a surface protective film as claimed in claim 1 or 2 is attached.