KR20220122593A - Surface-protective film and optical component attached with the same - Google Patents

Abstract

Provided are a surface-protective film and an optical component using the same, wherein the surface-protective film has a high effect of suppressing curling of an optical film, improves the handling of the optical film to which the surface-protective film adheres, and is easy to peel and remove after use. In addition, there is no need to replace the surface-protective film or remove contamination at the time of shipment. The surface-protective film (P) of the present invention comprises a first transparent film (1), a first adhesive layer (2), a second transparent film (3), and a second adhesive layer (4) that are sequentially laminated. The storage elastic modulus at 23℃ of the first adhesive layer (2) is 1.0 x 10^4 Pa or more and less than 8.0 x 10^4 Pa, and the adhesive force of the first adhesive layer (2) to glass is 5 N/25 mm or less.

Description

A surface protection film and an optical component to which it is attached

The present invention relates to a surface protection film and an optical component to which it is adhered.

Optical films, such as a polarizing plate, retardation plate, the lens film for displays, an antireflection film, a hard coat film, and the transparent conductive film for touch panels, are used for optical products, such as a display. When manufacturing and conveying an optical film or an optical component, a surface protection film is affixed on the surface of the said optical film, and it becomes possible to prevent the surface contamination and flaw in a post process. The external appearance inspection of the film for optics may be performed with the surface protection film affixed.

The surface protection film according to the prior art typically has a configuration in which a non-adhesive pressure-sensitive adhesive layer is formed on one side of a base film. An adhesive layer is a layer for sticking a surface protection film to the film for optics. The reason for making the pressure-sensitive adhesive layer non-adhesive is to enable smooth peeling of the used surface protection film from the optical film surface and to prevent adhesive residue from remaining.

In recent years, thinning and high-definition of displays are progressing, and accordingly, optical films are also being thinned. In addition, in order to thin the optical film, not only the thickness of each constituent member is made thin, but also the configuration is changed such as removing unnecessary members or adding the function of a plurality of members to one member to reduce the number of members.

For example, in a polarizing plate, the polarizing plate which has a structure in which the polarizer protective layer is laminated|stacked only on one side rather than both surfaces of a polarizer layer is increasing. In the case of a polarizing plate in which only one polarizer protective layer is formed with respect to the polarizer layer, since the structure in which the polarizer is sandwiched becomes asymmetric, it has a property of being easily bent (easy to curl) to one side. For this reason, the method of suppressing the curl of the film for optics is proposed.

For example, Patent Document 1 proposes a manufacturing method for suppressing curl of a polarizing plate by bonding together a protection film (surface protection film) having a Gurley method stiffness of 1.0 × 10 ² mgf or more and 1.0 × 10 ⁵ mgf or less. . As a specific example, the protection film whose thickness of the base film which consists of a biaxially stretched polyester resin is the range of 25 micrometers or more and 120 micrometers or less is mentioned.

Patent Document 2 proposes a polarizing plate in which the stiffness of a laminate comprising a polarizing plate body and a protection film (surface protection film) is prescribed. As a specific example, the polarizing plate using the protection film whose thickness of the base film which consists of a biaxially stretched polyester resin is 50 micrometers is mentioned.

Patent Document 3 proposes a protective film capable of favorably suppressing the curvature (curl) of a polarizing plate. Specifically, the protective film which has a 1st resin layer, a contact bonding layer, a 2nd resin layer, and an adhesive layer in this order is proposed. A value of the ratio of the thickness of the adhesive layer to the sum of the thickness of the first resin layer and the thickness of the second resin layer is 0.40 or less. The storage elastic modulus at 23°C of the adhesive layer is 8.0×10 ⁴ Pa or more and less than 1.0×10 ⁷ Pa. The protective film is integrally bonded to the polarizing plate surface and is peeled off integrally.

Since the surface protection film shown in Patent Documents 1 to 3 increases the thickness of the base film or uses a laminated film in which a resin layer/adhesive layer/resin layer is laminated as a base film, the elasticity of the film becomes strong, and the film for optics On the other hand, when peeling and removing a surface protection film after use, there exists a problem that peeling force becomes strong.

When peeling a surface protection film, a surface protection film is peeled at the peeling angle close|similar to 180 degrees with respect to the film for optics. At this time, the peeling force of the surface protection film is the sum of the force with which the adhesive of the surface protection film adheres to the optical film which is a to-be-adhered, and the force required when bending the surface protection film itself by 180 degrees. When the elasticity of the surface protection film becomes strong, the force required to bend the surface protection film itself by 180° also increases, so that the peeling force of the surface protection film becomes strong.

In recent years, along with thinning and high-definition displays, enlargement of displays for television and digital signage applications is also progressing. For the optical film used for such a large display, since the above-mentioned surface protection film has strong peeling force at the time of peeling, it is difficult to use.

Conventionally, in the manufacture of displays, components, such as a liquid crystal panel, a backlight unit, and a surface filter, have been procured in a set form by a panel manufacturer. This is called module procurement. However, in recent years, a procurement form called "open cell procurement" has become mainstream, especially for television applications. In open cell procurement, parts such as liquid crystal panels, backlight units, and surface filters are individually procured and assembled by TV manufacturers and OEMs. For this reason, distribution of liquid crystal panels in a semi-finished state is increasing.

In module procurement, the surface protection film affixed to the polarizing plate was peeling after panelization. However, in order to prevent adhesion of the dust and foreign material during liquid crystal panel conveyance with adoption of open cell procurement, the case where the surface protection film is not peeled is increasing after panel formation until just before setting. When shipping and conveying liquid crystal panels, the number of cases in which the surface protection film is kept clean by replacing the surface protection film contaminated during panel formation or removing the contamination of the surface protection film is increasing. In the surface protection films shown in Patent Documents 1 to 3, replacement of the surface protection film or removal of contamination of the surface protection film is required before shipment of a liquid crystal panel, etc., and it does not lead to process reduction or workability improvement.

Japanese Patent Laid-Open No. 2012-053078 Japanese Republished Publication No. WO2016/039296 Japanese Patent No. 5461640 Publication

One aspect of the present invention has been made in view of the above circumstances, and the effect of suppressing the curl of the optical film is high, the handling property of the optical film to which the surface protection film is attached is improved, and the peeling and removal after use is easy An object of the present invention is to provide a surface protection film that does not require replacement of the surface protection film or removal of contamination at the time of shipment as a surface protection film, and an optical component using the same.

In one embodiment of the present invention, a first transparent film, a first pressure-sensitive adhesive layer, a second transparent film, and a second pressure-sensitive adhesive layer are sequentially laminated, and the storage elastic modulus at 23° C. of the first pressure-sensitive adhesive layer is 1.0×10 It is ⁴ Pa or more and less than 8.0x10 ⁴ Pa, and provides the surface protection film whose adhesive force with respect to the glass of the said 1st adhesive layer is 5 N/25 mm or less.

The second pressure-sensitive adhesive layer may use a (meth)acrylic polymer as a base polymer.

It is preferable that the adhesive force of the second adhesive layer to the glass is 0.5N/25 mm or less, and the adhesive force of the first adhesive layer to the glass is higher than the adhesive force of the second adhesive layer to the glass.

It is preferable that the surface resistivity of the second pressure-sensitive adhesive layer is less than 1×10 ¹³ [Ω/□].

Another aspect of this invention provides the optical component to which the said surface protection film was stuck.

According to one aspect of the present invention, the effect of suppressing the curl of the optical film is high, the handling property of the optical film to which the surface protection film is attached is improved, and the surface protection film is easy to peel and remove after use. , it is possible to provide a surface protection film that does not require replacement of the surface protection film or removal of contamination when shipping a liquid crystal panel, and an optical component using the same.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of the surface protection film of embodiment.
It is a schematic structural diagram of an example of the optical component using the surface protection film of embodiment.
It is a schematic structural diagram which shows the structure which peeled and removed the adhesive film which consists of a 1st transparent film and a 1st adhesive layer from the optical component shown in FIG.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic block diagram of surface protection film P of embodiment. As shown in FIG. 1 , as for the surface protection film P, the 1st adhesive layer 2 is formed in the single side|surface of the 1st transparent film 1 . A second transparent film 3 is formed on the opposite side of the first transparent film 1 of the first pressure-sensitive adhesive layer 2 . A second pressure-sensitive adhesive layer 4 is formed on the opposite side of the first pressure-sensitive adhesive layer 2 of the second transparent film 3 . On the surface of the second pressure-sensitive adhesive layer 4, a release film 5 for protecting the pressure-sensitive adhesive surface is overlapped. That is, the surface protection film (P) comprises a first transparent film (1), a first pressure-sensitive adhesive layer (2), a second transparent film (3), a second pressure-sensitive adhesive layer (4), and a release film (5). These are stacked in this order and are configured. On the other hand, a film obtained by removing the release film 5 from the surface protection film P shown in FIG. 1 , that is, the first transparent film 1 , the first pressure-sensitive adhesive layer 2 , the second transparent film 3 , The film on which the 2nd adhesive layer 4 was laminated|stacked in this order is called surface protection film P.

A plastic film having transparency is used as the first transparent film 1 (base film). When the 1st transparent film 1 and the 2nd transparent film 3 have transparency, it becomes possible to perform an external appearance inspection of an optical component, with the surface protection film P affixed. As the plastic film for the first transparent film 1, preferably, a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate or polybutylene terephthalate is used. In addition to the polyester film, other plastic films can be used as long as they have required strength and have optical aptitude. The first transparent film 1 may be an unstretched film, or may be uniaxially or biaxially stretched. The first transparent film 1 may be a plastic film in which a draw ratio or an angle in the axial direction formed along with stretch crystallization is controlled.

Although the thickness of the 1st transparent film 1 is not specifically limited, For example, it is about 12-100 micrometers, Especially, it is preferable to set it as about 20-50 micrometers.

In the first transparent film 1, if necessary, on the opposite side (upper surface in FIG. 1) of the first pressure-sensitive adhesive layer 2, an antifouling layer for the purpose of preventing contamination of the surface, an antistatic layer, or for preventing scratches A hard-coat layer may be formed, or you may perform easy adhesion processing, such as a corona discharge treatment and an anchor-coat process.

When the 1st adhesive layer 2 adheres the surface protection film P to the film for optics, it is used for the objective of absorbing and relaxing the stress accompanying the curl of the film for optics. The material of the first pressure-sensitive adhesive layer 2 is not particularly limited, and a known material can be used as long as it satisfies properties such as having no adverse effects on adhesion to the transparent film, adhesion properties, stability, and the like.

As a material of the 1st adhesive layer 2, adhesives, such as a rubber type, an acrylic type, and a urethane type, are mentioned.

The rubber-based pressure-sensitive adhesive is a pressure-sensitive adhesive obtained by blending a tackifier, a softener, an anti-aging agent, a filler, or the like with an elastomer such as natural rubber or synthetic rubber, and a crosslinking agent may be added as needed.

An acrylic adhesive is the adhesive which added a hardening|curing agent and a tackifier as needed to the (meth)acrylic-type polymer, for example. The (meth)acrylic polymer includes a main monomer such as butyl acrylate (eg, n-butyl acrylate), 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, and acrylonitrile, vinyl acetate, Comonomers, such as methyl acrylate, methyl methacrylate, and ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, dimethyl acrylamide, N-methyl Polymers obtained by copolymerizing functional monomers such as allmethacrylamide, hydroxyl group-containing acrylic monomer, carboxyl group-containing acrylate, and polyoxyalkylene group-containing acrylic monomer are common. What is necessary is just to select an appropriate composition according to the characteristic requested|required of (meth)acrylic-type polymer. A (meth)acrylic polymer is used as a base polymer.

Examples of the curing agent include an isocyanate compound, an epoxy compound, a melamine compound, and a metal chelate compound. As a tackifier, a rosin type, a coumarone indene type, a terpene type, petroleum type, a phenol type, etc. are mentioned.

You may add additives, such as a curing catalyst, a pot life extender, an antistatic agent, a ultraviolet absorber, and antioxidant, to the 1st adhesive layer 2 as needed. As a material of the first pressure-sensitive adhesive layer 2, a pressure-sensitive adhesive in which a photoinitiator and a photocurable monomer or oligomer are added to the pressure-sensitive adhesive, and the monomer or oligomer polymerizes after light irradiation to change the adhesive strength.

What adjusted the kind and composition ratio of a hard segment and a soft segment is mentioned as for a urethane-type adhesive.

As a material of the 1st adhesive layer 2, an acrylic adhesive is especially preferable from heat resistance, durability, adhesiveness to the 2nd transparent film 3, etc.

As an adhesive containing an ultraviolet initiator and an ultraviolet curable monomer or oligomer in the pressure-sensitive adhesive for the first pressure-sensitive adhesive layer 2, a pressure-sensitive adhesive whose adhesive strength is lowered by irradiating ultraviolet rays may be used. By use of this adhesive, it can be made easy to peel and remove a 1st transparent film and a 1st adhesive layer from a 2nd transparent film at the time of shipment and conveyance of a liquid crystal panel. A thermal foaming agent may be added to the 1st adhesive layer 2 in the range which does not reduce transparency, and you may use the adhesive etc. which adhesive force falls by heating.

The 1st adhesive layer 2 is an adhesive layer whose adhesive force with respect to glass is 5N/25mm or less. It is preferable that the adhesive force in 180 degree peel with respect to glass, and the peeling rate of 300 mm/min of the 1st adhesive layer 2 is 5 N/25 mm or less.

When the adhesive force with respect to the glass of the 1st adhesive layer 2 is larger than 5 N/25 mm, the peeling force at the time of peeling and removing the surface protection film P increases, and there exists a possibility that workability|operativity may fall. In addition, when the adhesive force of the first pressure-sensitive adhesive layer 2 to glass is greater than 5 N/25 mm, if necessary (such as when shipping a liquid crystal panel), the pressure-sensitive adhesive film comprising the first transparent film 1 and the first pressure-sensitive adhesive layer 2 . There exists a possibility that it may become difficult to peel from the 2nd transparent film 3 .

The adhesive force with respect to the glass of the 1st adhesive layer 2 should just be 1 N/25 mm or more, for example. When the adhesive force with respect to the glass of the 1st adhesive layer 2 is 1N/25 mm or more, it is hard to occur wrong peeling of the adhesive film which consists of the 1st transparent film 1 and the 1st adhesive layer 2 .

When the workability at the time of peeling and removing the surface protection film P is considered, it is preferable that the adhesive force of the 1st adhesive layer 2 is higher than the adhesive force of the 2nd adhesive layer 4 . Thereby, it becomes easy to peel the adhesive film which consists of the 1st transparent film 1 and the 1st adhesive layer 2 from the 2nd transparent film 3 at the time of liquid crystal panel shipment etc.

The storage elastic modulus in 23 degreeC of the 1st pressure-sensitive adhesive layer 2 is 1.0×10 ⁴ Pa or more and less than 8.0×10 ⁴ Pa. When the storage elastic modulus of the first pressure-sensitive adhesive layer 2 is less than 1.0 × 10 ⁴ Pa, when the surface protection film P is wound and stored in a roll shape, the pressure-sensitive adhesive is pushed out from the edge portion or foreign substances are attached to the edge portion. There is a possibility that problems such as easiness may occur. Moreover, there exists a possibility that the curl suppression effect of an optical film may fall. When the storage elastic modulus of the 1st adhesive layer 2 is 8.0x10 ⁴ Pa or more, the peeling force at the time of peeling and removing the surface protection film P increases, and there exists a possibility that workability|operativity may fall.

Although the thickness of the 1st adhesive layer 2 is not specifically limited, It is common to set it as about 3-30 micrometers. By making the thickness of the 1st adhesive layer 2 into 3 micrometers or more, predetermined adhesive force is obtained. By making the thickness of the 1st adhesive layer 2 into 30 micrometers or less, cost can be suppressed.

What is necessary is just to use a well-known method as a method of forming the 1st adhesive layer 2 on the 1st transparent film 1 . For example, a method of coating an adhesive on the first transparent film 1 and drying and curing, a method of coating a second transparent film with an adhesive on the second transparent film, drying and curing, and then bonding the first transparent film, etc. are mentioned. . Specifically, known coating methods such as reverse coating, comma coating, gravure coating, slot die coating, Mayer bar coating, and air knife coating can be used.

A plastic film having transparency is used as the second transparent film 3 . When the 1st transparent film 1 and the 2nd transparent film 3 have transparency, it becomes possible to perform an external inspection of an optical component, with the surface protection film affixed. As the plastic film for the second transparent film 3, a polyester film such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate or polybutylene terephthalate is preferably used. In addition to the polyester film, other plastic films can be used as long as they have required strength and have optical aptitude. The second transparent film 3 may be an unstretched film, or may be uniaxially or biaxially stretched. The second transparent film 3 may be a plastic film in which a draw ratio or an angle in the axial direction formed along with the stretch crystallization is controlled.

Although the thickness of the 2nd transparent film 3 is not specifically limited, For example, it is about 12-100 micrometers, Especially, it is preferable to set it as about 19-50 micrometers.

The second transparent film 3 may be subjected to an easy-adhesive treatment such as a corona discharge treatment or an anchor coat treatment or an antistatic treatment to the side in contact with the first pressure-sensitive adhesive layer 2 if necessary. Moreover, you may give antistatic treatment, corona discharge treatment, easy adhesion treatment, such as an anchor coat treatment, to the opposite side (lower surface in FIG. 1) of the 1st adhesive layer 2 of the 2nd transparent film 3.

The 2nd adhesive layer 4 is formed in order to adhere the surface protection film P to the optical film which is a to-be-adhered body. The second pressure-sensitive adhesive layer 4 is a layer made of a non-adhesive pressure-sensitive adhesive. Using a non-adhesive pressure-sensitive adhesive means that the surface protection film (P) is not peeled off in the manufacturing process of the optical film, and after use, the surface protection film (P) can be peeled off smoothly when peeled and removed from the surface of the optical film, , and also to ensure that there is no adhesive residue.

It does not specifically limit about the material of the 2nd adhesive layer 4, Although well-known materials, such as adhesives, such as a rubber type, an acrylic type, and a urethane type, can be used, Especially, an acrylic adhesive is preferable.

An acrylic adhesive is the adhesive which added a hardening|curing agent and a tackifier as needed to the (meth)acrylic-type polymer, for example. The (meth)acrylic polymer includes a main monomer such as butyl acrylate (eg, n-butyl acrylate), 2-ethylhexyl acrylate, isooctyl acrylate, and isononyl acrylate, and acrylonitrile, vinyl acetate, Comonomers, such as methyl acrylate, methyl methacrylate, and ethyl acrylate, acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxybutyl acrylate, glycidyl methacrylate, dimethyl acrylamide, N-methyl Polymers obtained by copolymerizing functional monomers such as allmethacrylamide, hydroxyl group-containing acrylic monomer, carboxyl group-containing acrylate, and polyoxyalkylene group-containing acrylic monomer are common. What is necessary is just to select an appropriate composition according to the characteristic requested|required of (meth)acrylic-type polymer. A (meth)acrylic polymer is used as a base polymer.

Examples of the curing agent include an isocyanate compound, an epoxy compound, a melamine compound, and a metal chelate compound. As a tackifier, a rosin type, a coumarone indene type, a terpene type, petroleum type, a phenol type, etc. are mentioned. You may add additives, such as a curing catalyst, a pot life extender, an antistatic agent, a ultraviolet absorber, and antioxidant, to an acrylic adhesive as needed.

The antistatic agent preferably has good dispersion or compatibility with the (meth)acrylic polymer, for example, surfactants, ionic liquids, ionic solids, alkali metal salts, metal oxides, metal fine particles, conductive polymers, carbon, Carbon nanotubes, etc. are mentioned. As the antistatic agent, preferred are surfactants, ionic liquids, ionic solids, alkali metal salts, etc. in terms of transparency and affinity to (meth)acrylic polymers.

Nonionic, cationic, anionic, amphoteric, etc. are mentioned as surfactant. Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene fatty acid esters, glycerin fatty acid esters, propylene Glycol fatty acid esters, polyoxyalkylene modified silicones, etc. are mentioned. Examples of the cationic surfactant include alkyltrimethylammonium salts, dialkyldimethylammonium salts, and alkylbenzyldimethylammonium salts. Examples of the anionic surfactant include monoalkyl sulfates, alkyl polyoxyethylene sulfates, alkylbenzenesulfonates, and monoalkyl phosphates. Examples of the amphoteric surfactant include alkyldimethylamine oxide and alkylcarboxybetaine.

An ionic liquid is a non-polymeric substance that contains anions and cations and is liquid at room temperature. Examples of the cation moiety include cyclic amidine ions such as imidazolium ions, pyridinium ions, ammonium ions, sulfonium ions, and phosphonium ions. Anion moieties include C _n H _2n+1 COO ^- , C _n F _2n+1 COO ^- , N0 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 ² - , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , ClO ₄ ^- , BF ₄ ^- , PF ₆ ^- , AsF ₆ ^- , SbF ₆ ^- and the like.

An ionic solid includes an anion and a cation, and is a non-polymeric substance that is solid at room temperature. Examples of the cation moiety include nitrogen-containing onium ions such as pyridinium ions, imidazolium ions, pyrimidinium ions, pyrazolium ions, pyrrolidinium ions and ammonium ions, phosphonium ions, and sulfonium ions. Anionic moieties include hexafluorophosphate (PF ₆ ^- ), thiocyanate (SCN ^- ), alkylbenzenesulfonate (RC ₆ H ₄ SO ₃ ^- ), perchlorate (ClO ₄ ^- ), tetrafluoroborate (BF ₄ ^- ) and other inorganic or organic anions. A solid at room temperature can be obtained by selecting the chain length of the alkyl group, the position and number of substituents, and the like.

As an alkali metal salt, the metal salt containing alkali metals, such as lithium, sodium, potassium, is mentioned. Examples of the alkali metal salt include lithium trifluoromethylsulfonate (CF ₃ LiO ₃ S).

A compound containing a polyoxyalkylene structure may be added to the antistatic agent for stabilization of the ionic substance.

The amount of the antistatic agent added to the base polymer such as (meth)acrylic polymer varies depending on the type of antistatic component or the degree of compatibility of the base polymer, but may be set in consideration of surface resistivity, contamination of the adherend, and adhesion characteristics. .

You may add additives, such as a curing catalyst, a pot life extender, a ultraviolet absorber, and antioxidant, to an acrylic adhesive as needed.

When peeling and removing the surface protection film (P), when using it for the use with a fear of peeling electrification voltage, it is preferable to add an antistatic component (antistatic agent) to the 2nd adhesive layer 4 . In this case, the surface resistivity of the second pressure-sensitive adhesive layer 4 is preferably less than 1×10 ¹³ [Ω/□]. When the surface resistivity of the second pressure-sensitive adhesive layer 4 is less than 1×10 ¹³ [Ω/□], the peeling electrification voltage at the time of removing the surface protection film can be lowered. For this reason, antistatic performance can be improved.

Although the thickness of the 2nd adhesive layer 4 is not specifically limited, For example, it is about 3-50 micrometers, Especially, it is preferable to set it as about 5-30 micrometers.

Although it changes with the kind of surface treatment of the film for optics to which the surface protection film P is affixed, 0.5 N/25 mm or less of the adhesive force with respect to the glass of the 2nd adhesive layer 4 is preferable. It is preferable that the adhesive force in 180 degree peel with respect to glass, and the peeling rate of 300 mm/min of the 2nd adhesive layer 4 is 0.5 N/25 mm or less. Since the peeling force at the time of peeling and removing the surface protection film P as the adhesive force of the 2nd adhesive layer 4 is 0.5 N/25 mm or less becomes low, workability|operativity can be improved.

It is preferable that the 2nd adhesive layer 4 is a non-adhesive layer which has adhesiveness of the hardness whose peeling strength with respect to the surface of a to-be-adhered body (optical film) is about 0.03-0.3N/25mm. When the adhesive force of the 2nd adhesive layer 4 is 0.03 N/25 mm or more, it can suppress that the surface protection film P floats (ie, peels partially) in the manufacturing process of an optical film, or a conveyance process. Moreover, it becomes difficult to occur wrong peeling of the surface protection film P. If the adhesive force of the 2nd adhesive layer 4 is 0.3 N/25 mm or less, workability|operativity can be improved.

Lamination|stacking of the 2nd adhesive layer 4 with respect to the 2nd transparent film 3 may be performed by a well-known method, and it is not specifically limited. Specifically, (1) the pressure-sensitive adhesive used as the second pressure-sensitive adhesive layer 4 is applied to the second transparent film 3 and dried to form the second pressure-sensitive adhesive layer 4, and then applied to the surface of the second pressure-sensitive adhesive layer 4 A method of bonding the release film 5, (2) applying the pressure-sensitive adhesive serving as the second pressure-sensitive adhesive layer 4 to the release film 5, drying and forming the second pressure-sensitive adhesive layer 4, followed by a second transparent film 3 ) and a method of bonding them together.

What is necessary is just to form the 2nd adhesive layer 4 with respect to the 2nd transparent film 3 by a well-known method. Specifically, the pressure-sensitive adhesive may be coated by a coating means such as reverse coating, comma coating, gravure coating, slot die coating, Mayer bar coating, or air knife coating.

The surface protection film (P) is a second adhesive layer (4) of an adhesive sheet in which the first adhesive layer (2), the second transparent film (3), and the second adhesive layer (4) are formed on the first transparent film (1). ), the structure in which the surface of the peeling film 5 was protected is common. The surface protection film (P) does not use the release film (5), but the 1st transparent film (1) / 1st adhesive layer (2) / 2nd transparent film (3) / 2nd adhesive layer (4) is taped The shape of the product wound into a shape is also possible if necessary.

Although the release film 5 is not specifically limited, What gave peeling process using release agents, such as a silicone type release agent, on the surface of films, such as a polyester film, is illustrated.

It is a schematic block diagram of the optical component D which is an example of the optical component using the surface protection film P of embodiment.

As shown in FIG. 2, the optical component D affixed the surface protection film P shown in FIG. 1 on the surface of the film C for optics using the 2nd adhesive layer 4. Examples of the optical film (C) include a polarizing plate, a retardation plate, a lens film, a polarizing plate serving as a retardation plate, and a polarizing plate serving as a lens film. Such an optical component (D) can be used for manufacture of liquid crystal display devices, such as a liquid crystal display panel, and the optical system apparatus of various instruments.

Since the surface protection film (P) of embodiment has a multilayer structure which has two transparent films and two adhesive layers, the effect which suppresses the curl of the film for optics (C) is high. As for the surface protection film (P), it is hard to generate|occur|produce fold, unevenness|corrugation, etc. in the optical film (C) by the structure mentioned above. For this reason, the handling property of the film (C) for optics can be improved.

Generally, when a surface protection film is formed thickly, curl suppression property and handling property will become high, while the peelability of a surface protection film will fall. On the other hand, since the surface protection film P of embodiment uses the 1st adhesive layer 2 which has the above-mentioned characteristic, there exists an advantage of being easy to peel and remove after use.

Since the surface protection film (P) uses the first pressure-sensitive adhesive layer (2) having the above-described characteristics, the pressure-sensitive adhesive film composed of the first transparent film (1) and the first pressure-sensitive adhesive layer (2) can be peeled off and removed from other parts. can For example, FIG. 3 is a schematic structural diagram showing a configuration in which the adhesive film comprising the first transparent film 1 and the first adhesive layer 2 is peeled off from the optical component D. As shown in FIG. As shown in FIG. 3, the clean surface of a surface protection film can be exposed by peeling and removing an adhesion film. Therefore, replacement of the surface protection film and removal of contamination are unnecessary at the time of shipment of a liquid crystal panel, etc. Therefore, it is possible to reduce the number of steps, and it is possible to improve the yield, improve productivity, and improve workability.

The surface protection film (P) has a high suppression effect on the curl of the optical film, and the handling property of the optical film to which the surface protection film is affixed improves, and peels off after use, especially for the thinned optical film. easy to remove For this reason, the yield improvement of the manufacturing process of the thinned optical film, productivity improvement, and workability improvement can be aimed at.

Example

Next, the present invention is further described by way of examples. Hereinafter, "part by mass" may be simply referred to as "part".

(Preparation of the surface protection film of Example 1)

With respect to 100 parts of the base polymer which consists of butyl acrylate, methyl acrylate, dimethyl acrylamide, and a hydroxyl-containing acrylic monomer, 0.3 part of isocyanate type hardening|curing agents as a hardening|curing agent was mix|blended, and the adhesive (A) was obtained. The adhesive force with respect to glass of the adhesive layer formed by apply|coating the adhesive (A) to a 38-micrometer-thick biaxially stretched polyester film (coating thickness 10 micrometers after drying) was 3.8N/25mm.

3 parts of an isocyanate type hardening|curing agent as a hardening|curing agent was mix|blended with respect to 100 parts of the base polymer which consists of 2-ethylhexyl acrylate and a hydroxyl-containing acrylic monomer, and the adhesive (B) was obtained. The adhesive force to glass of the adhesive layer formed by apply|coating the adhesive (B) to a 38-micrometer-thick biaxially stretched polyester film (coating thickness after drying 20 micrometers) was 0.2N/25mm.

After drying the pressure-sensitive adhesive (A) on a colorless and transparent biaxially stretched polyester film (first transparent film) having a thickness of 25 µm, the pressure-sensitive adhesive (A) was applied to a thickness of 10 µm, and then dried in a hot air circulation oven at 120 ° C. for 2 minutes. .

Next, the 38-micrometer-thick colorless and transparent biaxially stretched polyester film (2nd transparent film) was pasted together on the surface (adhesive (A) application surface) of the adhesive (A). On the opposite side to the adhesive (A) of the bonded biaxially stretched polyester film, the adhesive (B) was applied so that the coating thickness after drying was set to 20 µm, and then dried in a hot air circulation type oven at 120°C for 2 minutes.

A release film (release film) in which a silicone-based release agent is coated on a 25 μm-thick biaxially stretched polyester film on the surface of the adhesive (B) (the adhesive (B) coated surface) was applied to the surface of the adhesive (B) and the release agent-treated surface (silicone-based release agent). The coated side) is bonded so that it is in contact. The obtained sample was aged for 3 days in 40 degreeC hot-air circulation type oven, and the surface protection film of Example 1 was obtained. The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive (A) is the first pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive (B) is the second pressure-sensitive adhesive layer.

(Preparation of the surface protection film of Example 2)

With respect to 100 parts of the base polymer consisting of butyl acrylate, methyl acrylate, dimethyl acrylamide, a hydroxyl group-containing acrylic monomer, and a carboxyl group-containing acrylate, 0.5 parts of an isocyanate-based curing agent as a curing agent was blended to obtain an adhesive (C). The adhesive force to glass of the adhesive layer (coating thickness 10 micrometers after drying) formed by apply|coating the adhesive (C) to a 38-micrometer-thick biaxially stretched polyester film was 4.8N/25mm.

Except having used the adhesive (C) instead of the adhesive (A), it carried out similarly to Example 1, and obtained the surface protection film of Example 2.

(Preparation of the surface protection film of Example 3)

With respect to 100 parts of the base polymer which consists of butyl acrylate, methyl acrylate, dimethyl acrylamide, and a hydroxyl-containing acrylic monomer, 1.5 parts of isocyanate type hardening|curing agents were mix|blended as a hardening|curing agent, and the adhesive (D) was obtained. The adhesive force to glass of the adhesive layer (coating thickness 10 micrometers after drying) formed by apply|coating the adhesive (D) to a 38-micrometer-thick biaxially stretched polyester film was 1.6N/25mm.

Except having used the adhesive (D) instead of the adhesive (A), it carried out similarly to Example 1, and obtained the surface protection film of Example 3.

(Preparation of the surface protection film of Example 4)

The surface protection of Example 4 was carried out in the same manner as in Example 1, except that a colorless and transparent biaxially stretched polyester film having a thickness of 25 µm was used instead of the biaxially stretched polyester film (second transparent film) having a thickness of 38 µm. got a film.

(Preparation of the surface protection film of Example 5)

To 100 parts of the base polymer consisting of 2-ethylhexyl acrylate, a polyoxyalkylene group-containing acrylic monomer, and a hydroxyl group-containing acrylic monomer, 0.1 parts of lithium trifluoromethylsulfonate as an antistatic agent and 3.0 parts of an isocyanate-based curing agent as a curing agent are blended. One adhesive (E) was obtained. The adhesive layer formed by applying the adhesive (E) to a 38 μm-thick biaxially stretched polyester film (thickness applied after drying 20 μm) has an adhesive force to glass of 0.15 N/25 mm, and the surface resistance value of the adhesive surface is 6.0×10 ¹¹ Ω/□.

Except having used the adhesive (E) instead of the adhesive (B), it carried out similarly to Example 1, and obtained the surface protection film of Example 5.

(Preparation of the surface protection film of Comparative Example 1)

After drying the pressure-sensitive adhesive (B) on a colorless and transparent biaxially stretched polyester film having a thickness of 38 µm, the pressure-sensitive adhesive (B) was applied to a thickness of 20 µm, and then dried in a hot air circulation oven at 120° C. for 2 minutes.

A release film (release film) in which a silicone-based release agent is coated on a 25 μm-thick biaxially stretched polyester film on the surface of the adhesive (B) (the adhesive (B) coated surface) was applied to the surface of the adhesive (B) and the release agent-treated surface (silicone-based release agent). The coated side) is bonded so that it is in contact. The obtained sample was aged for 3 days in a 40 degreeC hot-air circulation type oven, and the surface protection film of the comparative example 1 was obtained. An adhesive (B) turns into an adhesive layer.

(Preparation of the surface protection film of Comparative Example 2)

A surface protection film of Comparative Example 2 was obtained in the same manner as in Comparative Example 1 except that a colorless and transparent biaxially stretched polyester film having a thickness of 75 µm was used instead of the biaxially stretched polyester film having a thickness of 38 µm.

(Preparation of the surface protection film of Comparative Example 3)

A surface protection film of Comparative Example 3 was obtained in the same manner as in Comparative Example 1 except that a colorless and transparent biaxially stretched polyester film having a thickness of 100 µm was used instead of the biaxially stretched polyester film having a thickness of 38 µm.

(Preparation of the surface protection film of Comparative Example 4)

With respect to 100 parts of the base polymer consisting of butyl acrylate, methyl acrylate, dimethyl acrylamide, a hydroxyl group-containing acrylic monomer, and a carboxyl group-containing acrylate, 0.2 parts of an isocyanate-based curing agent as a curing agent was blended to obtain an adhesive (F). The adhesive force to glass of the adhesive layer (coating thickness 10 micrometers after drying) formed by apply|coating the adhesive (F) to a 38-micrometer-thick biaxially stretched polyester film was 6.5N/25mm.

Except having used the adhesive (F) instead of the adhesive (A), it carried out similarly to Example 1, and obtained the surface protection film of the comparative example 4.

(Preparation of the surface protection film of Comparative Example 5)

With respect to 100 parts of the base polymer which consists of butyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, and a hydroxyl-containing acrylic monomer, 0.3 part of an isocyanate type hardening|curing agent as a hardening|curing agent was mix|blended, and the adhesive (G) was obtained. The adhesive force with respect to glass of the adhesive layer (coating thickness 10 micrometers after drying) formed by apply|coating the adhesive (G) to a 38-micrometer-thick biaxially stretched polyester film was 3.2N/25mm.

Except having used the adhesive (G) instead of the adhesive (A), it carried out similarly to Example 1, and obtained the surface protection film of the comparative example 5.

(Preparation of the surface protection film of Comparative Example 6)

With respect to 100 parts of the base polymer which consists of 2-ethylhexyl acrylate, a hydroxyl-containing acrylic monomer, and a carboxyl group-containing acrylic monomer, 2.0 parts of an isocyanate type hardening|curing agent as a hardening|curing agent was mix|blended, and the adhesive (H) was obtained. The adhesive force to glass of the adhesive layer formed by apply|coating the adhesive (H) to a 38-micrometer-thick biaxially stretched polyester film (coating thickness after drying 20 micrometers) was 0.6N/25mm.

Except having used the adhesive (H) instead of the adhesive (B), it carried out similarly to Example 1, and obtained the surface protection film of the comparative example 6.

Hereinafter, it shows about the method of an evaluation test.

(Measurement of adhesive strength of adhesive layer)

After the adhesive is applied to a biaxially stretched polyester film having a thickness of 38 μm, it is dried in a hot air circulation type oven at 120° C. for 2 minutes. The release film which coated the silicone type release agent to the 25-micrometer-thick biaxially stretched polyester film is pasted together on the surface (adhesive-coated surface) of an adhesive. The obtained sample is aged for 3 days in a 40 degreeC hot-air circulation type oven.

The sample is cut into 25 mm wide and 150 mm long. After peeling a release film from a sample, this sample (surface protection film) is pasted together to a glass plate. The sample is pressed against the glass plate by reciprocating a 2 kg rubber roller once on the sample. Then, after leaving the sample and the glass plate under conditions of a temperature of 23°C and a relative humidity of 50% for 1 hour, the strength when the surface protection film was peeled at a peeling angle of 180° and a peeling rate of 300 mm/min using a tensile tester was measured. measure

(Measurement of storage modulus)

After apply|coating an adhesive to a 38-micrometer-thick biaxially stretched polyester film, it was dried for 2 minutes in 120 degreeC hot-air circulation type oven. The release film which coated the silicone type release agent to the 25-micrometer-thick biaxially stretched polyester film was pasted together on the surface (adhesive-coated surface) of an adhesive. The obtained sample is aged for 3 days in a 40 degreeC hot-air circulation type oven. The adhesive becomes an adhesive layer. After peeling the release film from the sample, the storage elastic modulus in 23 degreeC of an adhesive layer was measured with the viscoelasticity measuring apparatus (the UB company make, the dynamic viscoelasticity measuring apparatus Rheogel-E4000).

(Handling performance evaluation)

A polarizing plate sample (48 µm in total thickness) in which a triacetyl cellulose film is bonded to one side of a polarizer made of iodine and polyvinyl alcohol is cut into A4 size (210 mm x 297 mm). A surface protection film is pasted together on a polarizing plate using a desk laminator. Take one of the four corners of the polarizing plate on which the surface protection film is laminated, shake it back and forth 30 times, and visually observe the presence or absence of defects in appearance such as folds or irregularities on the polarizing plate. The thing without a fault was made into (circle), and the thing with a fault was made into X.

(Evaluation of curl inhibition)

A polarizing plate sample (48 µm in total thickness) in which a triacetyl cellulose film is bonded to one side of a polarizer made of iodine and polyvinyl alcohol is cut into A4 size (210 mm x 297 mm). A surface protection film is pasted together on a polarizing plate using a desk laminator. Place the curl convex side down on the test bench. The lifting distance from the surface of the test bench was measured for the four corners, and the largest value was taken as the curl amount. A thing of less than 10 mm of curl quantity made (triangle|delta), a thing of 10 mm or more and less than 20 mm (triangle|delta), and 20 mm or more thing was made into x.

(Protection film peelability evaluation)

A polarizing plate (a total thickness of 48 μm) in which a triacetyl cellulose film is laminated on one side of the polarizer is prepared. A sample of a surface protection film (protection film) is cut into a width of 25 mm and a length of 150 mm. After peeling a release film from a sample, this sample is pasted together on the triacetyl cellulose film surface of a polarizing plate. The sample is pressed toward the polarizing plate by reciprocating a 2 kg rubber roller on the sample once. After that, the sample and the polarizing plate were left for 24 hours under conditions of a temperature of 23° C. and a relative humidity of 50%, and then the strength when the surface protection film was peeled off at a peel angle of 180° and a peel rate of 30 m/min using a high-speed peel tester. measure Less than 1.8N/25mm was made into (circle), 1.8N/25mm or more and less than 2.5N/25mm were made into (triangle|delta), and 2.5N/25mm or more was made into x.

(Peelability of the first pressure-sensitive adhesive layer)

A triacetyl cellulose film is laminated on one side of the polarizer, and a polarizing plate (total thickness of 48 µm) having a pressure-sensitive adhesive layer and a release film bonded to the surface of the pressure-sensitive adhesive layer on the opposite side to the triacetyl cellulose film of the polarizer is prepared. A sample of the surface protection film is cut into a width of 25 mm and a length of 150 mm. After peeling a release film from a sample, this sample is pasted together to the triacetyl cellulose film surface of a polarizing plate, and the polarizing plate with a surface protection film is obtained. The sample is pressed toward the polarizing plate by reciprocating a 2 kg rubber roller on the sample once.

Then, the polarizing plate with a surface protection film is bonded together to a glass plate by peeling the release film pasted by the polarizing plate, and using a desk laminator. Thereafter, the polarizing plate and the glass plate with the surface protection film were left for 24 hours under the conditions of a temperature of 23° C. and a relative humidity of 50%, and then the pressure-sensitive adhesive film comprising the first transparent film and the first pressure-sensitive adhesive layer while pressing the second transparent film part by hand. When peeled from the 2nd transparent film, the thing which fell without the 2nd adhesive layer peeling was made into good (circle), and the thing which peeling or floatation generate|occur|produced in the 2nd adhesive layer was made into bad (x).

Table 1 shows the measurement results of each sample. In addition, as a reference value, Table 2 shows the measurement results of the electrification voltage at the time of peeling the surface protection film of Examples 1 and 5.

Table 1 and Table 2 show the following.

The surface protection film of Examples 1-5 had the high suppression effect with respect to the curl of the film for optics, and the handling property of the film for optics to which the surface protection film was affixed was favorable. The surface protection film of Examples 1-5 had become the surface protection film with which peeling and removal was easy after use so that the result of peeling force might show. The surface protection film of Examples 1-5 was able to peel and remove the adhesive film which consists of a 1st transparent film and a 1st adhesive layer so that the result of the peelability of a 1st adhesive layer may show.

Example 5 which added the antistatic agent to the 2nd adhesive layer became a surface protection film with a low peeling electrification voltage at the time of surface protection film removal.

On the other hand, the surface protection film of Comparative Examples 1-3 in which only the 2nd adhesive layer was formed in the polyester film handling property and curl suppression property by thickening the film thickness, but peelability fell. That is, in the surface protection films of Comparative Examples 1-3, all of curl suppression property, handling property, and peelability could not be made favorable.

Although the surface protection film of the comparative example 4 with high adhesive force of a 1st adhesive layer had favorable handling property and curl suppression property, it was not said that peeling force and the peelability of a 1st adhesive layer were favorable.

In the surface protection film of Comparative Example 5 with a low storage elastic modulus of the first pressure-sensitive adhesive layer, the curl suppression property was a poor result. Perhaps because of the curl, the peelability was poor.

Although the surface protection film of the comparative example 6 with high adhesive force of a 2nd adhesive layer had favorable handling property and curl suppression property, it was not said that peelability was favorable.

The present invention can be used, for example, in a polarizing plate, a retardation plate, an optical film such as a lens film, in a production process of an optical component, etc., in order to adhere to the surface of the optical component or the like to protect the surface. In particular, about the thinned optical film, the suppression effect with respect to the curl of the optical film is high, the handling property of the optical film to which the surface protection film was affixed improves, and peeling and removal is easy after use. For this reason, the yield improvement and productivity improvement of the manufacturing process of the thinned optical film can be aimed at. In addition, replacement of the surface protection film or removal of contamination becomes unnecessary at the time of shipment, etc., leading to workability improvement and productivity improvement.

One… 1st transparent film, 2... 1st adhesive layer, 3... 2nd transparent film, 4... 2nd adhesive layer, 5... Release film, C... Optical film, D... Optical components, P… surface protection film.

Claims (4)

A first transparent film, a first pressure-sensitive adhesive layer, a second transparent film, and a second pressure-sensitive adhesive layer are sequentially laminated,
The surface resistivity of the second pressure-sensitive adhesive layer is less than 1×10 ¹³ [Ω/□],
The adhesive force of the first pressure-sensitive adhesive layer is higher than that of the second pressure-sensitive adhesive layer,
The surface protection film whose adhesive force with respect to the glass of the said 2nd adhesive layer is 0.5N/25mm or less. The method of claim 1,
The second pressure-sensitive adhesive layer is a surface protection film using a (meth)acrylic polymer as a base polymer. 3. The method of claim 1 or 2,
The surface protection film by which the peeling film was pasted by the surface of the said 2nd adhesive layer. The optical component to which the surface protection film of Claim 1 or 2 was stuck.

Images