TWI726923B - Surface-protective film and optical component attached with the same - Google Patents

Abstract

The present invention provides a surface-protective film and an optical component of using the same. The surface-protective film can be used for an optical film with a non-planar surface. Also, the surface-protective film causes less contamination to the adherend, which does not change over time. Further, the surface-protective film has excellent antistatic performance upon peeling which does not degrade over time. The surface-protective film (10) is formed by applying a release film (5) with a release agent layer (4) on an adhesive layer (2). The release film (5) is formed by laminating the release agent layer (4) on one side of a resin film (3). The release agent layer (4) includes: a release agent with dimethyl polysiloxane as the main component, an antistatic agent which does not react with the release agent, and an ester plasticizer containing at least one ether bond. The antistatic agent is an ionic compound with a melting point less than 30℃. The antistatic agent and the ester plasticizer are transferred from the release agent layer (4) of the release film (5) to the surface of the adhesive layer (2), thereby reducing the electrostatic voltage when the adhesive layer (2) is peeled off from the adherend.

Description

Surface protective film and optical components with the film

The present invention relates to a surface protection film bonded to the surface of an optical element (hereinafter also referred to as an optical film) such as a polarizer, a retardation plate, and a lens film used for a display. In more detail, a surface protection film with less contamination to an adherend is provided, and further, a surface protection film with excellent anti-peeling static electricity performance that deteriorates with time, and an optical element using the surface protection film.

In the past, optical films such as polarizers, retardation plates, lens films for displays, anti-reflection films, hard coat films, transparent conductive films for touch panels, etc. have been manufactured and transported, and optical films such as displays using these films. In the case of products, a surface protective film is attached to the surface of the optical film to prevent dirt or scratches on the surface in the subsequent process. Regarding the appearance inspection of the optical film as an optical product, in order to save the time of peeling off the surface protective film and re-adhesive, and to improve work efficiency, the surface protective film may be directly performed in the state of bonding the optical film to the optical film.

Generally, in the preparation process of optical products, in order to prevent the adhesion of scratches or dirt, a surface protective film having an adhesive layer provided on one side of a base film is used. The surface protection film is bonded to the optical film via a micro-adhesive adhesive layer on. The reason for making the adhesive layer micro-adhesive is that when the used surface protection film is peeled and removed from the surface of the optical film, it can be easily peeled off, and the adhesive does not adhere and remain (that is, prevent the generation of glue residue) On the optical film that is the product of the adherend.

In recent years, in the production process of liquid crystal display panels, although the number of pieces generated is small, the peeling static voltage generated when the surface protective film bonded to the optical film is peeled and removed, which is used for control A phenomenon in which circuit elements such as driver ICs in the display screen of a liquid crystal display panel are destroyed, or the orientation of liquid crystal molecules is impaired.

In addition, in order to reduce the power consumption of the liquid crystal display panel, the driving voltage of the liquid crystal material has been lowered, and along with this, the breakdown voltage of the driver IC has also been lowered. Recently, it is required to make the stripping static voltage in the range of +0.7kV~-0.7kV.

In addition, in recent years, with the spread of 3D displays (stereoscopic displays), an FPR (Film Patterned Retarder) film may be bonded to the surface of an optical film such as a polarizer. 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, if the surface of an optical film such as a polarizer is contaminated with an adhesive or antistatic agent used in the surface protective film, there is a problem that it is difficult to adhere the FPR film. Therefore, it is required that the surface protection film used for this purpose has less pollution to the adherend.

In addition, in some liquid crystal panel manufacturers, as a method for evaluating the contamination of the surface protective film on the adherend, the following method is adopted: by temporarily peeling the surface protective film attached to the optical film such as a polarizer, It is a method to reattach it in the state, heat-treat it under the specified conditions, and then peel off the surface protection film and observe the surface of the adherend. In this evaluation method, if Even if the surface contamination of the adherend is slight, if there is a difference in the surface contamination of the adherend between the part where the air bubbles are mixed and the part in contact with the adhesive of the surface protective film, the surface contamination of the adherend is Traces of bubbles (sometimes called bubble penetration) remain. Therefore, as an evaluation method for the contamination of the adherend surface, this evaluation method is a very strict evaluation method. In recent years, even in the result of judgment by such a strict evaluation method, a surface protective film that does not pose a problem in terms of contamination to the surface of an adherend has been demanded.

When peeling the surface protective film from the optical film as the adherend, in order to prevent the occurrence of defects caused by the high peeling static voltage, some people have proposed a method for suppressing the peeling static voltage. The surface protective film of the adhesive layer of the antistatic agent.

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

In addition, Patent Document 2 discloses an adhesive composition composed of an ionic liquid and an acrylic polymer having an acid value of 1.0 or less, and adhesive sheets using the adhesive composition.

In addition, Patent Document 3 discloses an adhesive composition composed of an acrylic polymer, a polyether polyol compound, and an alkali metal salt treated with an anionic adsorbent compound, and a surface protective film using the adhesive composition .

In addition, Patent Document 4 discloses an adhesive composition composed of an ionic liquid, an alkali metal salt, and a polymer having a glass transition temperature of 0°C or less, and a surface protective film using the adhesive composition.

In addition, Patent Document 5 discloses a liquid ionic salt containing liquid ionic salt, containing poly Compound, an adhesive composition for a surface protection sheet of an optical element, and an adhesive sheet.

【Existing Technical Documents】 【Patent Literature】

[Patent Document 1] JP 2005-131957 A

[Patent Document 2] JP 2005-330464 A

[Patent Document 3] JP 2005-314476 A

[Patent Document 4] JP 2006-152235 A

[Patent Document 5] JP 2008-069261 A

In Patent Documents 1 to 5 described above, an antistatic agent is added to the inside of the adhesive layer. However, the thicker the thickness of the adhesive layer, or the longer the time elapsed after being attached to the adherend, the antistatic agent will transfer from the adhesive layer to the adherend relative to the adherend with the surface protective film attached. The more the amount. If the amount of the antistatic agent transferred to the adherend increases, the appearance quality of the optical film as the adherend may decrease, and the adhesiveness of the FPR film may decrease when the FPR film is bonded.

If the thickness of the adhesive layer is reduced in order to reduce the increase over time of the antistatic agent transferred from the adhesive layer to the adherend, other problems will arise. For example, when it is used for optical films with irregularities on the surface such as polarizers that have been treated for anti-glare, there is a problem that the adhesive layer is difficult to follow the irregularities on the surface of the optical film, and bubbles are mixed in. The adhesive area between the adhesive layer and the adhesive layer is reduced, resulting in a decrease in the adhesive force. The surface protective film is produced during use. Floating or falling off.

Therefore, there is a need for a surface protective film for optical films that can be bonded to optical films with uneven surfaces, has very little contamination on the adherend, and does not increase the contamination on the adherend even with time. In addition, there is a need for a surface protective film that can lower the peeling static voltage when the surface protective film is peeled from the adherend.

In order to solve these problems, the inventors of the present application have conducted in-depth research.

In order to reduce the contamination of the adherend and the increase in contamination over time, it is necessary to reduce the amount of the antistatic agent component in the adhesive layer that is presumed to be the cause of the contamination of the adherend. However, when reducing the amount of the antistatic agent component in the adhesive layer, the peeling static voltage when peeling the surface protective film from the adherend increases. Therefore, it has been studied to reduce the peeling static voltage when peeling the surface protective film from the adherend without increasing the absolute amount of the antistatic agent component in the adhesive layer.

As a result, it was found that by coating and drying an adhesive composition containing no antistatic agent to form an adhesive layer, only an appropriate amount of antistatic agent component is provided on the surface of the adhesive layer, not on the substrate The adhesive composition containing an antistatic agent is applied to one surface of the film and dried to form an adhesive layer, which can lower the peeling static voltage when peeling the surface protective film from the optical film as the adherend In this way, the present invention has been completed.

The present invention has been made in view of the above circumstances, and its object is to provide an optical film having irregularities on the surface that can be laminated, has less contamination on the adherend, and has low contamination on the adherend even with time. No change, and with A surface protective film with excellent anti-peeling static electricity performance that deteriorates over time, and an optical element using the surface protective film.

In order to solve the above-mentioned technical problems, the inventive concept of the present invention is that the surface protection film of the present invention coats and dries and laminates an adhesive layer without an antistatic agent on one side of the substrate film. An appropriate amount of antistatic agent is provided on the surface of the adhesive layer to lower the contamination of the adherend and at the same time lower the peeling static voltage when peeling from the optical film as the adherend.

In order to solve the above-mentioned technical problems, the present invention provides a surface protection film by forming an adhesive layer on one surface of a base film composed of a resin having transparency, and attaching a release agent to the adhesive layer A layered release film, characterized in that the release film is formed by laminating a release agent layer on one side of a resin film, wherein the release agent layer contains a release agent mainly composed of polydimethylsiloxane , An antistatic agent that does not react with the release agent, and an ester plasticizer containing at least one ether bond, the antistatic agent component is an ionic compound with a melting point of less than 30°C, and the antistatic agent component is compatible with The ester plasticizer is transferred from the release agent layer of the release film to the surface of the adhesive layer, thereby reducing the peeling static voltage when the adhesive layer is peeled from an adherend.

In addition, the adhesive layer is preferably formed by crosslinking an adhesive composition containing a (meth)acrylate copolymer and a crosslinking agent.

In addition, the peeling force when peeling the peeling film from the adhesive layer is preferably 0.2 N/50 mm or less.

In addition, the present invention provides a method of laminating the above-mentioned surface protective film Made of optical components.

The surface protective film of the present invention has less contamination to the adherend, and the low contamination to the adherend does not change even with time. In addition, the surface protection 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. In addition, according to the present invention, it is possible to provide a surface protective film with excellent anti-peeling static electricity performance that is not degraded over time, can lower the peeling static voltage generated when peeling from the optical film as an adherend, And an optical element using the surface protection film.

According to the surface protection film of the present invention, the surface of the optical film can be reliably protected, and therefore the productivity and yield can be improved.

1‧‧‧Base film

2‧‧‧Adhesive layer

3‧‧‧Resin film

4‧‧‧Release agent layer

5‧‧‧Peeling film

7‧‧‧Antistatic agent and ester plasticizer

8‧‧‧Adhesive (optical component)

10‧‧‧Surface protective film

11‧‧‧Peel off the surface protective film of the peeling film

20‧‧‧Optical components with surface protective film attached

[Fig. 1] is a cross-sectional view showing the concept of the surface protection film of the present invention; [Fig. 2] is a cross-sectional view showing the state after the release film is peeled from the surface protection film of the present invention; [Fig. 3] is a cross-sectional view showing the present invention A cross-sectional view of an embodiment of the optical element.

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

Fig. 1 is a schematic diagram showing the concept of the surface protection film of the present invention. The surface protection film 10 has an adhesive layer 2 formed on the surface of one surface of the transparent base film 1. On the surface of the adhesive layer 2, the release film 5 in which the release agent layer 4 is formed on the surface of the resin film 3 is bonded.

As the base film used in the surface protective film 10 of the present invention 1. Use a base film made of a resin having transparency and flexibility. In this way, the appearance inspection of the optical element can be performed in a state where the surface protection film is bonded to the optical element as an adherend. A film composed of a transparent resin used as the base film 1, suitable for use is polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polyethylene terephthalate. Polyester films such as butylene terephthalate. In addition to polyester films, films made of other resins may also be used as long as they have the required strength and optical compatibility. The base film 1 may be an unstretched film, or may be a uniaxially or biaxially stretched film. In addition, the stretching magnification of the stretched film or the orientation angle in the axial direction formed with the crystallization of the stretched film may be controlled to a specific value.

The thickness of the base film 1 used in the surface protection film 10 of the present invention is not particularly limited, but for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 20 to 50 μm is easier to handle, so it is more preferable .

In addition, if necessary, an antifouling layer to prevent surface fouling, an antistatic layer, a hard coat layer for scratch prevention, etc. may be provided on the surface of the base film 1 opposite to the surface on which the adhesive layer 2 is formed. In addition, the surface of the base film 1 may be subjected to easy adhesion treatments such as surface modification by corona discharge and application of an anchoring agent.

In addition, the adhesive layer 2 used in the surface protection film 10 of the present invention, as long as it is attached to the surface of the adherend, can be easily peeled off after use, and does not easily contaminate the adhesive of the adherend. Particularly limited, considering durability and the like after bonding to an optical film, an acrylic adhesive obtained by crosslinking a (meth)acrylate copolymer is generally used.

Examples of (meth)acrylate copolymers include n-butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate Main monomers such as acrylonitrile, vinyl acetate, methyl methacrylate, ethyl acrylate and other comonomers, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, A copolymer of functional monomers such as N-methylol methacrylamide and polyoxyalkylene-containing monomers such as methoxy polyethylene glycol methacrylate. (Meth) acrylate copolymer, its main monomer and other monomers can be (meth) acrylate, as a monomer other than the main monomer, it can also contain one or more than (meth) Monomers other than acrylates. Other monomers other than the main monomer can be selected from, but are not particularly limited to, the aforementioned comonomers, functional monomers, polyoxyalkylene-containing monomers, and the like.

Examples of the curing agent added to the adhesive layer 2 and the crosslinking agent for crosslinking the (meth)acrylate copolymer include isocyanate compounds, epoxy compounds, melamine compounds, metal chelate compounds, and the like. In addition, examples of thickeners include rosins, coumarone-indenes, terpenes, petroleum, phenols, and the like.

The thickness of the adhesive layer 2 used in the surface protection film 10 of the present invention is not particularly limited, but is preferably about 5 to 40 μm in thickness, and more preferably about 10 to 30 μm in thickness. In addition, since the workability when peeling the surface protective film from the adherend is excellent, it is preferable that the peel strength (adhesive force) of the surface protective film to the surface of the adherend is about 0.03~0.3N/25mm. Adhesive layer 2. In addition, since the workability when peeling off the peeling film 5 from the surface protective film 10 is excellent, the peeling force when peeling off the peeling film 5 from the adhesive layer 2 is preferably 0.2 N/50 mm or less, and more preferably 0.14 N/50 mm or less.

In addition, the release film 5 used in the surface protection film 10 of the present invention is formed by laminating a release agent layer 4 on one side of the resin film 3, and the release agent layer 4 contains There are a release agent containing polydimethylsiloxane as a main component, an antistatic agent that does not react with the release agent, and an ester plasticizer containing at least one ether bond. In the release film used in the surface protection film of the present invention, the antistatic agent component is preferably an ionic compound having a melting point of less than 30°C.

As the resin film 3, a polyester film, a polyamide film, a polyethylene film, a polypropylene film, a polyimide film, etc. can be mentioned. Since it has excellent transparency and low price, a polyester film is particularly preferred. The resin film may be an unstretched film, or a uniaxially or biaxially stretched film. In addition, the stretch magnification of the stretched film and the orientation angle in the axial direction formed with the crystallization of the stretched film can be controlled to specific values.

The thickness of the resin film 3 is not particularly limited, but for example, a thickness of about 12 to 100 μm is preferable, and a thickness of about 16 to 50 μm is easier to handle, which is more preferable.

In addition, the surface of the resin film 3 may be subjected to surface modification by corona discharge, application of an anchoring agent, and other easy-adhesion treatments as needed.

Examples of the release agent comprising polydimethylsiloxane as the main component of the release agent layer 4 include well-known silicone release agents such as addition reaction type, condensation reaction type, cationic polymerization type, and radical polymerization type. . The products of addition reaction type silicone stripping agent sold on the market, for example, include KS-776A, KS-847T, KS-779H, KS-837, KS-778, KS-830 (Shin-Etsu Chemical Co., Ltd. ) Manufacturing), SRX-211, SRX-345, SRX-357, SD7333, SD7220, SD7223, LTC-300B, LTC-350G, LTC-310 (manufactured by Dow Corning Toray Co., Ltd.), etc. Examples of commercially available products of condensation reaction type silicone release agents include SRX-290 and SYLOFF-23 (manufactured by Dow Corning Toray Co., Ltd.). Cationic polymerized silicones sold on the market Examples of products of the release agent include TPR-6501, TPR-6500, UV9300, VU9315, UV9430 (manufactured by Momentive Performance Materials Company), X62-7622 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like. The free radical polymerization type silicone release agent products sold on the market include X62-7205 (manufactured by Shin-Etsu Chemical Co., Ltd.) and so on.

As the antistatic agent constituting the release agent layer 4, it is preferable that the dispersibility with respect to the release agent solution containing polydimethylsiloxane as the main component is good, and does not hinder those containing polydimethylsiloxane as the main component. Cured antistatic agent for release agent. In addition, in order to transfer from the release agent layer 4 to the surface of the adhesive layer 2 and impart an antistatic effect to the adhesive layer 2, an antistatic agent that does not react with a release agent mainly composed of polydimethylsiloxane is preferable. Ionic compounds with a melting point of less than 30°C are very suitable as such antistatic agents.

The ionic compound having a melting point of less than 30°C is an ionic compound having a cation and an anion. Examples of the cation include cyclic amidine ions such as imidazole ions, pyridinium ions, ammonium ions, alium ions, and phosphine ions. Further, as the anion, include ^{_{C n H 2n + 1 COO -}} , C n F 2n + 1 COO -, NO 3 -, C n F 2n + 1 SO 3 -, (C n F 2n + 1 SO 2) _{^{2 N -, (C n F}} 2n + 1 SO 2) 3 C -, PO 4 3-, AlCl 4 -, Al 2 Cl 7 -, ClO 4 -, BF 4 -, PF 6 -, AsF 6 -, SbF ₆ ^- Wait.

The amount of the antistatic agent added to the release agent whose main component is polydimethylsiloxane varies depending on the type of antistatic agent or the affinity with the release agent. The amount of antistatic agent added can be set in consideration of the expected peeling static voltage when peeling the surface protective film from the adherend, the contamination to the adherend, and the adhesion characteristics.

Esters containing at least one ether bond constituting the release agent layer 4 The plasticizer is used to improve the antistatic performance of the surface of the adhesive layer 2. As the plasticizer contained in the release agent layer 4, a plasticizer with good dispersibility to a release agent solution containing polydimethylsiloxane as a main component is preferable. In addition, a plasticizer that does not hinder the curing of the release agent whose main component is polydimethylsiloxane is preferable. In addition, the plasticizer plays a role of assisting the transfer of the antistatic agent contained in the release agent layer 4 from the release agent layer 4 to the surface of the adhesive layer 2. Therefore, the plasticizer is preferably one that does not react with the release agent whose main component is polydimethylsiloxane. As such a plasticizer, an ester plasticizer containing at least one ether bond in the molecule is suitable.

At least one ether bond in the molecule of the ester plasticizer is required to increase the affinity with the antistatic agent. In addition, in the surface protection film of the present invention, when the release agent layer is in contact with the adhesive layer, a plasticizer is used in order to efficiently transfer the antistatic agent component from the release agent layer to the surface of the adhesive layer. . In the present invention, in order to increase the affinity between the release agent layer and the adhesive layer, a plasticizer containing an ester group is suitably used.

Examples of ester plasticizers containing at least one ether bond in the molecule include diethylene glycol di-2-ethylhexanoate, tetraethylene glycol di-2-ethylhexanoate, and hexaethyl Glycol di-2-ethylhexanoate, triethylene glycol diethyl butyrate, polyethylene glycol diethyl butyrate, polypropylene glycol diethylhexanoate, triethylene glycol diphenylmethyl Ester, tetraethylene glycol dibenzoate, polyethylene glycol dibenzoate, polypropylene glycol dibenzoate, or polyethylene glycol-2-ethylhexanoic acid benzoate. One type or two or more types can be selected from these ester plasticizer groups and used. Here, ethyl hexanoate is also called ethyl hexanoate, ethyl hexanoate, ethyl hexane acid ester) etc. Benzoate (benzoate) refers to benzoate.

The addition amount of the ester plasticizer relative to the release agent with polydimethylsiloxane as the main component depends on the type of plasticizer and the affinity with the release agent, but it can be considered from the adherend Set the desired peeling static voltage when peeling off the surface protective film, the contamination to the adherend, and the adhesion characteristics.

There is no particular limitation on the mixing method between the release agent containing polydimethylsiloxane as the main component, the antistatic agent, and the ester plasticizer. Any of the following methods can be used: a method of adding and mixing an antistatic agent and an ester plasticizer to a release agent with polydimethylsiloxane as the main component, and then adding and mixing a catalyst for curing of the release agent; using organic After the solvent predilutes the release agent with polydimethylsiloxane as the main component, the method of adding and mixing antistatic agent, ester plasticizer and the catalyst for curing of the release agent; will use polydimethylsiloxane as The main component of the release agent is diluted in an organic solvent in advance, a catalyst is added and mixed, and then an antistatic agent and an ester plasticizer are added and mixed. In addition, if necessary, an adhesion improving agent such as a silane coupling agent, or a material that assists the antistatic effect, such as a polyoxyalkylene group-containing compound, can be added.

The mixing ratio of the release agent with polydimethylsiloxane as the main component, the antistatic agent and the ester plasticizer is not particularly limited, but it is compared with the release agent with polydimethylsiloxane as the main component. The solid content is 100 parts, and the total of the antistatic agent and the ester plasticizer based on the solid content is preferably a ratio of about 5 to 100 parts. Relative to 100 parts of the solid content of the release agent with polydimethylsiloxane as the main component, if the total amount of the antistatic agent and the ester plasticizer converted into the solid content is less than 5 parts, then The transfer amount of the antistatic agent and the ester plasticizer to the surface of the adhesive layer is reduced, and it is difficult to exert the antistatic function imparted to the adhesive. In addition, If the total amount of antistatic agent and ester plasticizer is converted to a solid content of 100 parts relative to 100 parts of the solid content of the release agent with polydimethylsiloxane as the main component, then Antistatic agents and ester plasticizers and release agents based on polydimethylsiloxane are also transferred to the surface of the adhesive layer at the same time, so the adhesive properties of the adhesive may be reduced.

The method of forming the adhesive layer 2 on the base film 1 of the surface protection film 10 of this invention, and the method of bonding the peeling film 5 can be performed by a well-known method, and it is not specifically limited. Specifically, the following methods can be cited: (1) The resin composition for forming the adhesive layer 2 is coated on one side of the base film 1, and dried to form the adhesive layer, and then the release film 5 is attached Method; (2) The resin composition used to form the adhesive layer 2 is coated on the surface of the release film 5 and dried to form the adhesive layer, and then the method of laminating the base film 1, etc., use any of them The method can be used.

In addition, the method of forming the adhesive layer 2 on the surface of the base film 1 may be a well-known method. Specifically, known coating methods such as reverse coating, knife coating, gravure coating, slot extrusion coating, Meyer bar coating, and air knife coating can be used.

In addition, in the same manner, the release agent layer 4 may be formed on the resin film 3 by using a known method. Specifically, well-known coating methods such as gravure coating, Meyer bar coating, and air knife coating can be used.

The surface protection film 10 of the present invention having the above-mentioned structure preferably has a surface potential of +0.7 kV to -0.7 kV when the adhesive layer is peeled from the optical film as an adherend. Furthermore, the surface potential is more preferably +0.5kV to -0.5kV, particularly preferably +0.1kV to -0.1kV. The surface potential can It is adjusted by adding or subtracting the types and addition amount of the antistatic agent and the ester plasticizer contained in the release agent layer.

Fig. 2 is a cross-sectional view showing a state after the peeling film is peeled from the surface protection film of the present invention.

By peeling off the release film 5 from the surface protection film 10 shown in FIG. 1, part of the antistatic agent and ester plasticizer (reference numeral 7) contained in the release agent layer 4 of the release film 5 is transferred It is printed (attached) to the surface of the adhesive layer 2 of the surface protective film 10. Therefore, in FIG. 2, the antistatic agent and the ester plasticizer transferred on the surface of the adhesive layer 2 of the surface protective film 11 in the state where the release film is peeled off are indicated by the spots of reference numeral 7. By transferring the components 7 of the antistatic agent and the ester plasticizer from the release film 5 to the surface of the adhesive layer 2, the adhesive layer 2 is removed from the adherend as compared with the adhesive layer 2 before the transfer. The peeling static voltage during peeling decreases. In addition, the peeling static voltage when peeling the adhesive layer from the adherend can be measured by a known method. For example, after attaching the surface protective film to the adherend such as a polarizer, use a high-speed peeling tester (manufactured by TESTER SANGYO CO,. LTD.) to peel the surface protective film at a peeling speed of 40m per minute, while using a surface potentiometer (Manufactured by KEYENCE CORPORATION) The surface potential of the adherend surface was measured every 10 ms, and the maximum value of the absolute value of the surface potential at this time was used as the peeling static voltage (kV).

In the surface protection film of the present invention, when the surface protection film 11 in the state where the release film is peeled off as shown in FIG. 2 is attached to the adherend, the antistatic film is transferred to the surface of the adhesive layer 2 Agents and ester plasticizers are in contact with the surface of the adherend. Thereby, the peeling static voltage when peeling the surface protection film from the adherend again can be suppressed low.

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

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

That is, Fig. 3 shows an optical element 20 to which the surface protection film 11 of the present invention is bonded. As an optical element, optical films, such as a polarizing plate, a retardation plate, a lens film, a polarizing plate also used as a retardation plate, and a polarizing plate also used as a lens film, are mentioned. The above-mentioned optical element can be used as a constituent element of a liquid crystal display device such as a liquid crystal display panel, an optical system device of various measuring instruments, and the like. In addition, examples of optical elements include optical films such as anti-reflection films, hard coat films, and transparent conductive films for touch panels.

According to the optical element of the present invention, when the surface protective film 11 is peeled and removed from the optical element (optical film) as an adherend, the static voltage for suppressing peeling can be sufficiently low. Therefore, there is no need to worry about damaging circuit elements such as driver ICs, TFT elements, gate line driver circuits, etc., and the production efficiency in the manufacturing process of liquid crystal display panels and the like can be improved, and the reliability of the production process can be maintained.

[Examples]

Next, the present invention will be further explained based on the embodiments.

(Example 1)

(Production of surface protective film)

5 parts by weight of addition reaction type silicone (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), and 7.5 parts by weight of tri-n-butylmethylammonium bis( 10% ethyl acetate solution of trifluoromethanesulfonamide (manufactured by 3M, FC-4400), 0.75 parts by weight of tetraethylene glycol Di-2-ethylhexanoate, 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, 0.05 parts by weight of platinum catalyst (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-212 ) Mix, stir and mix, and prepare a coating material for forming the release agent layer of Example 1. The coating used to form the release agent layer of Example 1 was coated on the surface of a polyethylene terephthalate film with a thickness of 38 μm using a Meyer bar so that the thickness after drying was 0.2 μm. Drying was performed in a hot-air loop oven for 1 minute, and the peeling film of Example 1 was obtained. On the other hand, relative to the copolymerization of 90 parts by weight of 2-ethylhexyl acrylate, 7 parts by weight of methoxy polyethylene glycol (400) methacrylate, and 3 parts by weight of 2-hydroxyethyl acrylate 100 parts by weight of the 30% ethyl acetate solution of the adhesive polymer composed of the material, stirring and mixing 1.5 parts by weight of an isocyanate curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX), preparation example 1 The adhesive composition. In addition, CORONATE (registered trademark) HX is a curing agent of the HDI type (hexamethylene diisocyanate type).

After coating the adhesive composition of Example 1 on the surface of a polyethylene terephthalate film with a thickness of 38 μm so that the thickness after drying is 20 μm, it was dried using a hot air circulation oven at 100°C 2 minutes to form an adhesive layer. After that, on the surface of the adhesive layer, the release film of Example 1 prepared above was bonded via a release agent layer (silicone-treated surface). The obtained adhesive film was kept at a temperature of 40° C. for 5 days to cure the adhesive layer to obtain the surface protective film of Example 1.

(Comparative example 1)

5 parts by weight of addition reaction type silicone (manufactured by Dow Corning Toray Co., Ltd., trade name: SRX-345), 95 parts by weight of a 1:1 mixed solvent of toluene and ethyl acetate, 0.05 parts by weight Platinum catalyst (Dow Corning Toray Co., Ltd., trade name: SRX-212) was mixed, stirred and mixed, and a paint for forming the release agent layer of Comparative Example 1 was prepared. On the surface of a polyethylene terephthalate film with a thickness of 38 μm, the paint used to form the release agent layer of Comparative Example 1 was coated with a thickness of 0.2 μm after drying using a Meyer rod. The hot air circulation oven at 120° C. was dried for 1 minute to obtain a peeling film of Comparative Example 1. On the other hand, with respect to 100 parts by weight of the adhesive polymer solution of Example 1 (the ethyl acetate solution with a solid content of 30%), 3 parts by weight, which is an ionic compound with a melting point of 27.5°C, was added and mixed with 3 parts by weight. A 10% ethyl acetate solution of butylmethylammonium bis(trifluoromethanesulfonyl)imide (manufactured by 3M, FC-4400), 1.5 parts by weight of isocyanate curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX), the adhesive composition of Comparative Example 1 was prepared.

On the surface of a polyethylene terephthalate film with a thickness of 38 μm, the adhesive composition of Comparative Example 1 was applied so that the thickness after drying was 20 μm, and then a hot air circulation oven at 100°C was used. Dry for 2 minutes to form an adhesive layer. After that, the release agent layer (silicone-treated surface) of the release film of Comparative Example 1 prepared above was bonded to the surface of the adhesive layer. The obtained adhesive film was kept at a temperature of 40° C. for 5 days to cure the adhesive layer to obtain a surface protective film of Comparative Example 1.

(Comparative example 2)

The surface protective film of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that tri-n-butylmethylammonium bis(trifluoromethanesulfonate)imide, which is an ionic compound with a melting point of 27.5°C, was not added to the adhesive layer .

(Comparative example 3)

In addition to not adding tetraethylene glycol di-2- ester as an ester plasticizer in the release agent layer Except for ethylhexanoate, in the same manner as in Example 1, a surface protective film of Comparative Example 3 was obtained.

(Example 2)

In addition to substituting the adhesive composition of Example 1, 58 parts by weight of 2-ethylhexyl acrylate, 38 parts by weight of butyl acrylate, and 4 parts by weight of 2-hydroxyethyl acrylate were used relative to 100 parts by weight. Adhesive polymer composed of 30% ethyl acetate solution, and 1.2 parts by weight of isocyanate curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX) is added and mixed with an adhesive composition Except for that, in the same manner as in Example 1, the surface protective film of Example 2 was obtained.

(Example 3)

In addition to substituting the adhesive composition of Example 1, an adhesive polymer composed of 96 parts by weight of 2-ethylhexyl acrylate and 4 parts by weight of 2-hydroxyethyl acrylate copolymer was used relative to 100 parts by weight. The same as Example 1 except for the adhesive composition obtained by adding and mixing 1.2 parts by weight of an isocyanate curing agent (manufactured by TOSOH CORPORATION, trade name: CORONATE (registered trademark) HX) with 30% ethyl acetate solution of , The surface protection film of Example 3 was obtained.

The method and results of the evaluation test are shown below.

<Measurement method of peeling force of peeling film>

The sample of the surface protection film was cut to a width of 50 mm and a length of 150 mm. Under the test environment of 23℃×50%RH, the tensile tester was used to measure the strength when peeling off the peeling film along the direction of 180° at a peeling speed of 300mm/min, and this was used as the peeling force of the peeling film (N/50mm ).

<Method for Measuring Adhesion of Surface Protective Film>

The anti-glare and low-reflection treatment polarizer (AG-LR polarizer) was bonded to the surface of the glass plate using a double-sided adhesive tape for a laminator. Then, a surface protective film cut into a width of 25 mm was bonded on the surface of the polarizing plate, and then stored in a test environment of 23° C.×50% RH for one day. After that, the tensile tester was used to measure the strength when peeling off the surface protective film along a 180° direction at a peeling speed of 300 mm/min, and this was used as the adhesive force (N/25mm).

<Measurement method of peeling static voltage of surface protective film>

The anti-glare and low-reflection treatment polarizer (AG-LR polarizer) was bonded to the surface of the glass plate using a double-sided adhesive tape for a laminator. Then, a surface protective film cut into a width of 25 mm was bonded on the surface of the polarizing plate, and then stored in a test environment of 23° C.×50% RH for one day. After that, a high-speed peel tester (manufactured by TESTER SANGYO CO,. LTD.) was used to peel off the surface protective film at a peeling speed of 40m per minute, while a surface potentiometer (manufactured by KEYENCE CORPORATION) was used to measure the surface potential of the polarizer surface every 10 ms, The maximum value of the absolute value of the surface potential at this time was taken as the peeling static voltage (kV).

<Determination method of surface fouling of surface protective film>

The anti-glare and low-reflection treatment polarizer (AG-LR polarizer) was bonded to the surface of the glass plate using a double-sided adhesive tape for a laminator. Then, a surface protective film cut into a width of 25 mm was bonded on the surface of the polarizer, and then stored in a test environment of 23° C.×50% RH for 3 days and 30 days. After that, the surface protection film was peeled off, and whether there was contamination on the surface of the polarizing plate was visually observed. As a criterion for determining the surface contamination, the case where there is no contamination transfer on the polarizing plate was evaluated as (○), and the case where contamination transfer on the polarizing plate was confirmed was evaluated as (×).

Regarding the obtained surface protection of Examples 1 to 3 and Comparative Examples 1 to 3 The measurement results of the film are shown in Tables 1-2. "2EHA" is 2-ethylhexyl acrylate, "# 400G" is methoxy polyethylene glycol (400) methacrylate, "HEA" is 2-hydroxyethyl acrylate, "BA" is butyl acrylate , "FC4400" is tri-n-butylmethylammonium bis(trifluoromethanesulfonyl)imide, and "plasticizer" is tetraethylene glycol di-2-ethylhexanoate. In Tables 1 and 2, the composition of the adhesive layer is expressed in parts by weight so that the total amount of the adhesive polymer (solid content) is approximately 100 parts by weight. Therefore, in the adhesive layer of Comparative Example 1, the weight ratio of the adhesive polymer (solid content) to FC4400 is 30 parts by weight: 0.3 parts by weight=100 parts by weight: 1.0 parts by weight.

【Table 2】

According to the measurement results shown in Table 1 and Table 2, the following conclusions can be obtained.

The surface protection films of Examples 1 to 3 of the present invention have moderate adhesion, do not pollute the surface of the adherend, and have a low peeling static voltage when the surface protection film is peeled from the adherend.

On the other hand, the surface protective film of Comparative Example 1 containing an antistatic agent in the adhesive layer has a low peel static voltage when the surface protective film is peeled from the adherend, which is good, but it contaminates the adherend after peeling increase.

In addition, in the surface protective film of Comparative Example 2, in which both the adhesive layer of the surface protective film and the release agent layer of the release film did not contain an antistatic agent, the contamination to the adherend was good, but the surface was protected Peeling static electricity when the film is peeled from the adherend Increased pressure.

That is, the surface protective film of Comparative Example 1 in which the adhesive layer of the surface protective film contains an antistatic agent, and the comparative example in which neither the adhesive layer of the surface protective film nor the release agent layer of the release film contains an antistatic agent In the surface protective film of 2, it is difficult to balance the reduction of the peeling static voltage and the contamination of the adherend.

On the other hand, after the release agent layer of the release film contains the antistatic agent and the ester plasticizer, the antistatic agent and the ester plasticizer of the release agent layer are transferred only on the surface of the adhesive layer. In the surface protective films of Examples 1 to 3, since the addition of a small amount of ester plasticizer has a significant effect of reducing the peeling static voltage, there is no pollution to the adherend, and the peeling static resistance performance is also good.

In addition, in the surface protective film of Comparative Example 3, which contained only the antistatic agent in the release agent layer and did not contain the ester plasticizer, there was no contamination to the adherend, and the anti-peeling static electricity performance was also good. However, when compared with the surface protection films of Examples 1 to 3 in which an antistatic agent and an ester plasticizer were contained in the release agent layer, the peeling static voltage increased.

【Industrial Utilization Possibility】

The surface protection film of the present invention can be bonded to the surface of the optical element or the like to protect the surface in the production process of optical films such as polarizers, retardation plates, lens films, and other various optical elements. In addition, the surface protection film of the present invention can lower the amount of static voltage generated when the surface protection film is peeled from the adherend, and the anti-peeling static electricity changes with time and the pollution to the adherend is less. Increasing the yield of the production process is of great industrial use value.

1‧‧‧Base film

2‧‧‧Adhesive layer

3‧‧‧Resin film

4‧‧‧Release agent layer

5‧‧‧Peeling film

7‧‧‧Antistatic agent and ester plasticizer

10‧‧‧Surface protective film

Claims (4)

A surface protection film formed by forming an adhesive layer on one surface of a substrate film composed of a resin having transparency, and bonding a release film having a release agent layer on the adhesive layer It is characterized in that: the release film is formed by laminating the release agent layer on one side of a resin film, wherein the release agent layer contains a release agent mainly composed of polydimethylsiloxane and does not interact with The release agent reacts with an antistatic agent and an ester plasticizer containing at least one ether bond. The antistatic agent component is an ionic compound having a cation and anion with a melting point of less than 30°C. The cation is a ring One selected from the group consisting of amidine ions, pyridine ions, ammonium ions, sulfonium ions, and phosphine ions, the antistatic agent component and the ester plasticizer are transferred from the release agent layer of the release film to the The surface of the adhesive layer reduces the peeling static voltage when the adhesive layer is peeled from the adherend. The surface protection film described in the first item of the patent application is characterized in that the adhesive layer is formed by cross-linking an adhesive composition containing a (meth)acrylate copolymer and a cross-linking agent. The surface protection film described in item 1 or 2 of the scope of patent application is characterized in that the peeling force when the peeling film is peeled from the adhesive layer is 0.2N/50mm or less. An optical element formed by laminating the surface protective film described in any one of items 1 to 3 in the scope of patent application.

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