JP2002328226A - Cohesive film for protection of optical sheet before inspection and method for manufacturing optical sheet using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cohesive film for protection of an optical sheet before inspection which is excellent in the protecting performance for an optical sheet before inspection, permit highly accurate inspection of defects in the optical sheet before inspection while the cohesive film is stuck thereto and when an adhesive, a hard coating agent or the like is applied on the surface of the optical sheet after the cohesive film is removed, shows the good appearance of the coating, and to provide the optical sheet with the protective film before inspection and a method for manufacturing the optical sheet by using the above film. SOLUTION: The cohesive film for protection of an optical sheet before inspection prepared by forming a cohesive layer on one surface of a plastic film, has a transmittance of >=80% for all rays and has a removable contamination preventing layer laminated on the back face of the cohesive film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polarizing plate, a retardation plate, a lens sheet, an anti-reflection (AR) sheet, an anti-glare (AG) used for various displays.
At the time of applying an adhesive or a hard coat agent, applying a heat treatment, cutting, assembling an optical sheet such as a sheet,
The present invention relates to a pressure-sensitive adhesive film for protecting an optical sheet before inspection, which can be used to prevent stains and scratches during transportation, and a method for manufacturing an optical sheet before inspection and an optical sheet with a protective film using the same.

[0002]

2. Description of the Related Art Polarizing plates used in various displays,
Retardation plate, lens sheet, anti-reflection (A
R) sheets, anti-glare (AG) sheets, etc., optical sheets such as anti-glare (AG) sheets become defective when the surface is stained or scratched. Prevention is common practice. As such an adhesive film, a film obtained by applying an adhesive to a plastic film such as polyethylene or polypropylene or laminating by a co-extrusion method is used.

[0003]

However, due to the recent improvement in display accuracy of the display, the accuracy required for dirt and scratches on the optical sheet has been increased, and the demand for cost reduction of products has been increased. A new function is required for the pressure-sensitive adhesive film for protecting the front optical sheet surface.

As one of them, there is a demand for a highly transparent adhesive film. The conventional pressure-sensitive adhesive film has a disadvantage that the pressure-sensitive adhesive film has to be peeled off once and then the pressure-sensitive adhesive film must be reapplied after the inspection for defect inspection of the optical sheet before inspection. Therefore, a highly transparent adhesive film is disclosed in
No. 120, Japanese Patent Application Laid-Open No. 11-70629, and the like, which have transparency that enables defect inspection, adhere to the back of the adhesive film during the optical sheet manufacturing process, There has been a problem that it is difficult to distinguish scratches from optical sheet defects.

In the case of a conventional pressure-sensitive adhesive film, if an adhesive or a hard coat agent is directly applied to the surface of the optical sheet after the pressure-sensitive adhesive film is peeled off, minute coating unevenness is likely to occur, and when assembled into a product, the brightness and color are reduced. There is a defect that unevenness occurs. For example, a triacetyl cellulose (TAC) film used for a polarizing plate usually has an adhesive for bonding to a polarizing film on one side and a hard coat agent on the other side. There are various methods for producing the TAC film for the polarizing plate, and among them, an adhesive film is attached to prevent dirt and scratches during the production process, and then the adhesive film is peeled off and the adhesive is removed. Or a hard coat agent. When conventional adhesive films are used for such work, minute unevenness of coating is likely to occur when an adhesive or hard coat agent is applied, and when assembled into a display product, defects such as uneven brightness and poor color unevenness occur. was there.

The present invention solves these drawbacks, is excellent in the protection performance of the optical sheet before inspection, and is capable of accurately performing a defect inspection of the optical sheet before inspection with an adhesive film attached. It is an object of the present invention to provide an adhesive film for use and a method for producing an optical sheet using the same. Further, the present invention also provides a pre-inspection optical sheet protective pressure-sensitive adhesive film having features such as good coating appearance when an adhesive or a hard coat agent is applied to the optical sheet surface after peeling off the pressure-sensitive adhesive film, and An object of the present invention is to provide a method for manufacturing an optical sheet with a protective film before inspection and an optical sheet using the same.

[0007]

SUMMARY OF THE INVENTION The present invention provides an adhesive sheet for protecting an optical sheet before inspection provided with a peelable dirt preventing layer in the production of an optical sheet.
Paste this on the optical sheet before inspection, peel off the stain prevention layer just before the defect inspection, perform the defect inspection with the adhesive film attached, and paste the adhesive film until just before applying the adhesive or hard coat agent after the inspection By keeping the state, it is possible to save the trouble of re-attaching the adhesive film, and at the same time, prevent foreign substances and dirt from adhering in the step of peeling and re-adhering the adhesive film, which has been performed by the conventional method, and to reduce the optical sheet surface. It can be kept clean.

That is, the present invention relates to the following. (1) In an adhesive film having a pressure-sensitive adhesive layer provided on one side of a plastic film and having a total light transmittance of 80% or more, the surface opposite to the adhesive layer of the adhesive film (hereinafter, referred to as the
An adhesive sheet for protecting an optical sheet before inspection, wherein a peelable dirt preventing layer is laminated on the back surface. (2) The pre-inspection optical sheet protection according to the above (1), wherein the stain prevention layer is composed of an adhesive single-layer film or a multilayer film, and the multilayer film has adhesiveness on at least one side. Adhesive film. (3) The optical sheet before inspection according to the above (1) or (2), wherein the adhesion of the stain prevention layer to the back surface of the adhesive film is in the range of 0.01 N / 25 mm to 1.0 N / 25 mm. Adhesive film for protection. (4) The adhesive strength of the adhesive film to the pre-test optical sheet is greater than the adhesive strength of the stain prevention layer to the back of the adhesive film, from 0.01 N / 25 mm to 1.0 N / 25 m.
m. The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to any one of the above (1) to (3), wherein the range is m. (5) The pressure-sensitive adhesive layer is attached to a glass surface, and a change in water contact angle of the glass surface after treatment at 100 ° C. for 1 minute and peeling is within 30 degrees with respect to an initial value. ) The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to any one of (4) to (4). (6) The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to any one of the above (1) to (5), wherein a polyester film is adhered to the surface of the pressure-sensitive adhesive layer as a separator. (7) In a pre-inspection optical sheet with a protective film in which an adhesive layer is provided on one surface of a plastic film and an optical sheet before inspection is provided on the surface of the adhesive layer, on the surface (back surface) opposite to the adhesive layer of the adhesive film. A pre-inspection optical sheet with a protective film, wherein a stain prevention layer which is peeled off during a defect inspection of the pre-inspection optical sheet is laminated. ((8) An adhesive film for protecting the pre-inspection optical sheet is attached to the surface of the optical sheet before the inspection, and immediately before performing the defect inspection of the optical sheet before the inspection, the dirt preventing layer of the pre-inspection optical sheet is removed. A method for producing an optical sheet, comprising: performing a defect inspection with a pressure-sensitive adhesive film adhered to a front optical sheet; and peeling the pressure-sensitive adhesive film immediately before applying an adhesive or a hard coat agent.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below with reference to FIG. The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to the present invention has a structure in which a pressure-sensitive adhesive layer 2 is provided on one surface of a plastic film 1 to form a pressure-sensitive adhesive film 5, and a dirt prevention layer 3 is provided on the plastic film side of the pressure-sensitive adhesive film 5. A configuration is adopted in which the polyester separator 4 is attached to the adhesive layer side of the film 5. In the case of the latter configuration, when the protective adhesive film of the present invention is attached to the optical sheet before inspection, the polyester separator 4 is peeled off and the adhesive layer surface is attached.

Hereinafter, the present invention will be described specifically.
The pressure-sensitive adhesive film of the present invention has high transparency, and has a total light transmittance of 80% or more. It is more preferably at least 90%. If the total light transmittance is less than 80%, it is not possible to accurately perform a defect inspection of the optical sheet before inspection with the adhesive film adhered. The total light transmittance here is JIS
According to K-7105, it was measured by an integrating sphere turbidity meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000).

For the support of the pressure-sensitive adhesive film of the present invention, a plastic film having high transparency is used for the reasons described above. For example, a polyester film, a polypropylene film, a polyethylene film, a polycarbonate film, a polystyrene film, a triacetate film and the like can be mentioned. Among these, a polyester film excellent in productivity and processability can be preferably used. Further, such a polyester film includes a biaxially stretched film, a uniaxially stretched film, and a non-stretched film, and any of them can be used. In particular, a biaxially stretched film is generally used and can be preferably used.

The thickness of the plastic film is 5
~ 200 µm is preferably used. More preferably,
It is 8 to 50 μm. If the thickness is less than 5 μm, the film strength is insufficient, sufficient protection performance is hardly obtained, and problems such as breakage of the film at the time of peeling occur. On the other hand, when the thickness is more than 200 μm, problems such as deterioration of light transmittance of the film and an increase in cost of the film itself occur.

The antifouling layer of the present invention is used to prevent the back surface of the pressure-sensitive adhesive film from adhering dirt and scratches in the manufacturing process, and is peeled off from the pressure-sensitive adhesive film at the time of defect inspection. is there.

As a single-layer film having an adhesive property as a stain prevention layer, low-density polyethylene, polyvinyl chloride,
Single-layer films such as ethylene-vinyl acetate copolymer resin and ethylene-α-olefin copolymer resin are exemplified.

Further, examples of the multilayer film having at least one surface having adhesiveness include a film having at least two layers composed of a support layer and an adhesive layer.

As the support layer, low density polyethylene,
Medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α olefin copolymer resin,
Examples thereof include films made of polypropylene, polyvinyl chloride, polyester, or the like alone or a mixture of two or more, or films obtained by laminating these.

As the adhesive layer, low-density polyethylene, medium-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer resin, ethylene-vinyl acetate copolymer resin, styrene-butadiene copolymer resin, styrene-
Examples thereof include an ethylene-butylene copolymer resin, an acrylic rubber, a natural rubber, a silicone rubber, and a synthetic rubber. These may be used alone or in a mixture of two or more.

Examples of the method of laminating the support layer and the adhesive layer include a coextrusion method, a heat laminating method, and a coating method. In the case where the adhesive layer is a resin component, the coextrusion method is used. Is preferably a coating method.

The thickness of the stain prevention layer is 5 to 200 μm.
m is preferably used. More preferably, 8-50μ
m. If the thickness is less than 5 μm, a problem occurs in that the scratches of the stain prevention layer are transferred to the back surface of the adhesive film. Also, 200
If the thickness exceeds μm, problems such as an increase in the cost of the stain prevention layer itself occur.

The antifouling layer of the present invention has an adhesive force to the back surface of the adhesive film of 0.01 N / 25 mm to 1.
It is preferably in the range of 0 N / 25 mm. More preferably, 0.05N / 25mm to 0.2N / 25m
m. If the adhesive strength is higher than 1.0 N / 25 mm, problems such as peeling of the adhesive film from the pre-inspection optical sheet when peeling the stain prevention layer from the adhesive film are likely to occur. Further, if the thickness is less than 0.01 N / 25 mm, the adhesive strength is too low, and there is a problem that the adhesive film is easily peeled off from the adhesive film in various steps.

The pressure-sensitive adhesive film of the present invention has a pressure-sensitive adhesive strength to an optical sheet before inspection of 0.01 N / 25 mm to 1.0 N.
/ 25 mm is preferable. More preferably, it is 0.05 N / 25 mm to 0.2 N / 25 mm. If the adhesive strength is higher than 1.0 N / 25 mm, problems such as deformation of the pre-inspection optical sheet when peeling the adhesive film from the pre-inspection optical sheet are likely to occur. Further, if the adhesive strength is low, such as less than 0.01 N / 25 mm, there is a problem that the adhesive sheet is easily peeled off from the optical sheet before inspection in various steps.

In the above adhesive force, it is necessary that (adhesive force of the adhesive film to the optical sheet before inspection)> (adhesive force of the stain prevention layer to the back surface of the adhesive film). This is because, if the adhesion of the stain prevention layer to the back surface of the adhesive film is larger, the stain prevention layer is easily peeled off at the interface between the adhesive film and the optical sheet before inspection when the stain prevention layer is peeled off.

The pressure-sensitive adhesive layer used in the present invention has good coating appearance when an adhesive or a hard coat agent is coated on the surface of the optical sheet after the pressure-sensitive adhesive film is peeled off. An adhesive having a change in water contact angle of the glass surface after peeling after treatment at 100 ° C. for 1 minute for 1 minute is preferably used. More preferably, the change in the contact angle is within 20 degrees. When the contact angle exceeds 30 degrees, when a liquid material such as an adhesive or a hard coat agent is directly applied to the optical sheet from which the pressure-sensitive adhesive film has been peeled off, minute coating unevenness occurs. This causes color unevenness failure.

Further, in the pressure-sensitive adhesive layer of the present invention, a highly transparent pressure-sensitive adhesive having a total light transmittance of 80% or more of the pressure-sensitive adhesive film can be easily obtained. A crosslinked acrylic pressure-sensitive adhesive is preferably used because a pressure-sensitive adhesive whose water contact angle change on the glass surface is within 30 degrees with respect to the initial value is easily obtained. There is no restriction.

When a cross-linked acrylic pressure-sensitive adhesive is used, the cross-linked acrylic pressure-sensitive adhesive may be butyl acrylate,
Low Tg (glass transition temperature) monomers such as ethyl acrylate and 2-ethylhexyl acrylate as main monomers and copolymerization with functional group monomers such as acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, acrylamide and acrylonitrile. By crosslinking the acrylic copolymer obtained in the above with a crosslinking agent.

As the acrylic copolymer, those having a weight average molecular weight in the range of 100,000 to 1,000,000 are preferably used. If the weight average molecular weight is less than 100,000, the amount of low molecular weight substances increases, so that the adhesive film is adhered to the glass surface and the change in the water contact angle on the glass surface after peeling after treatment at 100 ° C. for 1 minute increases. appear.
On the other hand, if the weight average molecular weight exceeds 1,000,000, the viscosity when dissolved in a solvent is high, and it becomes difficult to obtain a smooth pressure-sensitive adhesive coated appearance when formed into a pressure-sensitive adhesive film. Furthermore, the molecular weight dispersity (value obtained by dividing the weight average molecular weight by the number average molecular weight) in the acrylic copolymer is preferably 5 or less. If it is larger than 5, the amount of low molecular weight in the acrylic copolymer increases, so that it is applied as an adhesive film to the glass surface and the change in the water contact angle of the glass surface after treatment at 100 ° C. for 1 minute and separation is increased. Failures are likely to occur. The acrylic copolymer having a Tg of -20 ° C or lower can be preferably used. If the Tg is higher than −20 ° C., the pressure-sensitive adhesive becomes hard, and it becomes difficult to obtain a suitable pressure-sensitive adhesive force to the optical sheet before inspection.

As the above crosslinking agent, known crosslinking agents such as isocyanate type, melamine type and epoxy type can be used. Further, as this cross-linking agent, a trifunctional,
A polyfunctional crosslinking agent such as tetrafunctional is more preferably used. Further, the crosslinked state in the pressure-sensitive adhesive is preferably 70% or more when evaluated by gel fraction. If the gel fraction is lower than 70%, a problem such as a large change in the water contact angle of the glass surface after sticking to a glass surface as a pressure-sensitive adhesive film, treating at 100 ° C. for 1 minute, and peeling is likely to occur.

In the present invention, the thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film is usually 1 to 30 μm.

The method for forming the pressure-sensitive adhesive layer here includes a method of dissolving in an organic solvent and applying a pressure-sensitive adhesive whose viscosity has been adjusted.
Known methods such as a method of melting and applying an adhesive or a method of dispersing and applying in water can be used.However, as a method of forming a cross-linked acrylic adhesive, an adhesive prepared by dissolving in an organic solvent and adjusting the viscosity is used. A method of applying an agent is generally used. Further, the pressure-sensitive adhesive film of the present invention may have a surface treatment such as a corona treatment or a plasma treatment on the surface of the plastic film, or an undercoating agent (primer) in order to improve the adhesion between the plastic film support and the pressure-sensitive adhesive layer, if necessary. ) May be applied. In addition, a back surface treatment agent is applied to the back of the adhesive film for the purpose of adjusting the unwinding property of the adhesive film from the roll, and to prevent the generation of static electricity when the adhesive film is unwound or peeled from the optical sheet before inspection. For example, an antistatic agent may be applied on the back surface of the adhesive film or between the support and the adhesive layer. As the back surface treatment agent here, a simple substance or a modified substance such as a silicone resin, a fluorine resin, a polyvinyl alcohol resin, a resin having an alkyl group,
Mixtures are mentioned. Examples of the antistatic agent here include various cationic antistatic agents having good transparency, for example, having a cationic group such as a quaternary ammonium salt, a pyridium salt, and a tertiary to tertiary amino group, and sulfonic acid. Anionic antistatic agents having anionic groups such as bases, sulfate bases and phosphate bases; amphoteric antistatic agents such as amino acids and amino acid sulfates; nonionics such as amino alcohols, glycerin and polyethylene glycol Examples include various antistatic agents such as a system antistatic agent, and a high molecular weight antistatic agent obtained by increasing the molecular weight of these antistatic agents.

The pressure-sensitive adhesive film of the present invention preferably has a pressure-sensitive adhesive layer surface to which a separator is attached in order to obtain a smooth surface. Examples of the separator include a plastic film separator and a paper separator. Among them, a biaxially stretched polyester separator having features such as excellent film surface smoothness and relatively low cost can be more preferably used. A release agent may be applied to the surface of the separator for the purpose of adjusting the releasability from the adhesive film. Examples of the release agent include simple substances, modified substances, and mixtures of generally used silicone resins, fluorine resins, polyvinyl alcohol resins, resins having an alkyl group, and the like.

Hereinafter, the manufacturing process of the optical sheet according to the present invention will be described with reference to FIG. 2 in comparison with the conventional manufacturing process. Conventionally, the adhesive film 5 was attached to the optical sheet 6 before inspection, and after various manufacturing processes, the adhesive film 5 that protected the optical sheet 6 before inspection was peeled off immediately before the defect inspection of the optical sheet 6 before inspection. By doing so, the dirt adhering to the surface is removed and defect inspection is performed. After that, the adhesive film 5 is again adhered to the surface of the optical sheet 6 ′ to prevent dirt adhering to the surface by transportation or the like until the adhesive or the hard coat agent 4 is applied. According to the present invention, the pressure-sensitive adhesive film 11 for protecting the optical sheet before inspection provided with the stain prevention layer 3 is adhered to the optical sheet 6 before inspection, and after various manufacturing processes, the stain prevention is performed immediately before the defect inspection of the optical sheet 6 before inspection. After peeling off the layer 3 and performing a defect inspection,
Immediately before the application of the adhesive or the hard coat agent 9, the state is maintained, and after the adhesive film 5 is peeled off, the adhesive or the hard coat agent 9 is applied.

[0032]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 An acrylic copolymer using 2-ethylhexyl acrylate and ethyl acrylate as main monomers and hydroxyethyl methacrylate and acrylic acid as functional monomers was synthesized by a solution polymerization method. The weight average molecular weight of this synthesized acrylic copolymer was 400,000, the molecular weight dispersity was 4.0, and the glass transition point was −.
37 ° C.

An adhesive solution was prepared by mixing 10 parts by weight of a polyfunctional isocyanate crosslinking agent (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.) with 100 parts by weight of this acrylic copolymer, and a transparent biaxial film having a thickness of 25 μm was prepared. 10% dry thickness on the corona treated surface of stretched polyester film
It was coated and dried to a thickness of μm. After laminating a biaxially stretched polyester film separator coated with a silicone release agent having a thickness of 25 μm on the adhesive surface,
A layer film (co-extruded film of polyethylene and ethylene-vinyl acetate copolymer resin, thickness: 40 μm) was laminated on the back surface of the adhesive film. This adhesive film is placed at room temperature (2
(3 ° C.) for one week, and after sufficient aging, it was used for the test.

Example 2 An adhesive film was produced in the same manner as in Example 1 except that the amount of the polyfunctional isocyanate crosslinking agent was changed to 4 parts by weight.

Example 3 Example 1 was repeated except that an adhesive film (a 5 μm thick natural rubber layer was formed on a 60 μm thick polyethylene by a coating method) was used instead of the two-layer film. A pressure-sensitive adhesive film was produced in the same manner as described above.

Comparative Example 1 An adhesive film was produced in the same manner as in Example 1 except that nothing was laminated on the back of the adhesive film.

Reference Example 1 Example 1 was repeated except that an adhesive film (a natural rubber layer having a thickness of 25 μm was formed on a polyethylene film having a thickness of 60 μm by a coating method) was used instead of the two-layer film. A pressure-sensitive adhesive film was produced in the same manner as described above.

Reference Example 2 An adhesive film was produced in the same manner as in Example 1 except that the amount of the polyfunctional isocyanate crosslinking agent was changed to 1 part by weight.

The characteristic values of the pressure-sensitive adhesive films in the above Examples, Comparative Examples and Reference Examples were measured by the following methods. The results are shown in Table 1.

(1) Total light transmittance The total light transmittance of the pressure-sensitive adhesive film after the anti-staining layer was removed was measured using an integrating sphere turbidimeter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.). JIS K7105
It measured according to. (2) Water contact angle of glass surface Adhesive film is adhered to a glass plate using a rubber roll while taking care not to cause air bubbles, heat treated at 100 ° C for 1 minute, cooled to room temperature, and then peeled off the adhesive film ,
The water contact angle of the glass surface was measured. The contact angle was measured using an automatic contact angle measuring device (CA-W1 manufactured by Kyowa Interface Science Co., Ltd.).
50 type) was used. The initial water contact angle of the glass surface was 20.3 degrees as a result of the measurement. (3) Adhesive Strength The adhesive film prepared above was attached to a triacetyl cellulose film using a rubber roll. After standing in a room at 23 ° C. for 24 hours, the adhesive strength of the stain preventing layer to the back of the adhesive film was measured using a tensile tester (TRC-1210, manufactured by Orientec Co., Ltd.), and then the adhesive layer of the adhesive film was measured. Was measured for adhesion to a triacetylcellulose film. The measurement was performed at 180 ° peeling and a peeling speed of 0.3 m / min. (4) Appearance inspection (I) The adhesive film prepared above was attached to a triacetyl cellulose film using a rubber roll. After the anti-staining layer was peeled off, the appearance of the triacetyl cellulose film was visually evaluated with the pressure-sensitive adhesive film attached. Thereafter, the adhesive film was peeled off, and the appearance of the triacetylcellulose film was similarly visually evaluated, and evaluated according to the following criteria. ：: All the foreign substances and scratches caused by the triacetyl cellulose film observed in a state where the adhesive film was peeled were also observed in a state where the adhesive film was stuck. ×: All of the foreign substances derived from the triacetyl cellulose film observed in the state where the adhesive film was peeled off could not be observed in the state where the adhesive film was adhered. (5) Appearance inspection (II) The adhesive film produced above was attached to a triacetyl cellulose film using a rubber roll. afterwards,
After the back surface was rubbed five times with a dry cloth to remove the stain preventing layer, the appearance of the triacetyl cellulose film was visually evaluated with the adhesive film stuck. Thereafter, the adhesive film was peeled off, and the appearance of the triacetylcellulose film was similarly visually evaluated, and evaluated according to the following criteria. ：: All the foreign substances and scratches caused by the triacetyl cellulose film observed in a state where the adhesive film was peeled were also observed in a state where the adhesive film was stuck. ×: Foreign matter other than that caused by the triacetyl cellulose film,
Wounds could be observed. (6) Adhesive coatability The adhesive film prepared above was adhered to the saponified surface of the triacetyl cellulose film using a rubber roll while paying attention to prevent air bubbles from entering, and at room temperature (23 ° C.)
, The adhesive film was peeled off, an acrylic adhesive was applied, and dried. Paste the obtained triacetyl cellulose film with adhesive on a transparent glass plate,
The appearance was visually observed. In addition, an acrylic pressure-sensitive adhesive was similarly applied to the saponified surface of the triacetylcellulose film to which the pressure-sensitive adhesive film was not stuck, dried, stuck to a transparent glass plate, and visually observed for appearance. The difference in appearance between when the adhesive film was applied and when it was not applied was evaluated according to the following criteria. ：: There is no difference in the abnormal appearance level caused by uneven application of the adhesive when the adhesive film is applied and when the adhesive film is not applied. ×: Abnormal appearance caused by uneven application of the adhesive is more remarkably observed when the adhesive film is applied and when the adhesive film is not applied.

[0042]

[Table 1] * 1: The entire adhesive film was peeled off from the optical sheet, and the objective evaluation could not be performed.

As is clear from Table 1, Examples 1 to 3, which are the pressure-sensitive adhesive films of the present invention, can perform the defect inspection of the optical sheet before inspection accurately with the pressure-sensitive adhesive film adhered thereto. When the adhesive was applied to the surface of the optical sheet after the adhesive film was peeled off, the coated appearance of the adhesive was good.

On the other hand, in Comparative Example 1, when a defect inspection of the optical sheet before inspection was performed with the adhesive film adhered, an error occurred in which a scratch on the back surface of the adhesive film was determined to be a defect of the optical sheet before inspection.

In Reference Example 1, when the dirt preventing layer was to be peeled off, the pressure-sensitive adhesive film was also peeled off, resulting in a problem that the number of reattaching steps increased.

Further, in Reference Example 2, when an adhesive was applied to the surface of the optical sheet after the pressure-sensitive adhesive film was peeled off, there was a problem that the appearance of coating was deteriorated.

[0047]

According to the present invention, the protective performance of the optical sheet before inspection is excellent, the defect inspection of the optical sheet before inspection can be performed accurately with the adhesive film adhered, and the adhesive film is peeled off. It is possible to obtain a pressure-sensitive adhesive film for protecting an optical sheet before inspection, which has features such as good coating appearance when an adhesive or a hard coat agent is applied to the surface of the optical sheet later.

[Brief description of the drawings]

FIG. 1 is a structural view of an adhesive film for protecting an optical sheet before inspection according to the present invention.

FIG. 2 shows a conventional example and a process according to the present invention in a part of a conventional optical sheet manufacturing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic film 2 Adhesive layer 3 Stain prevention layer 4 Polyester film 5 Adhesive film 6 Optical sheet before inspection 6 'Optical sheet 7 Dirt 8 Inspection device 9 Adhesive or hard coat agent 10 Adhesive or hard coat agent application nozzle 11 Before inspection Adhesive film for optical sheet protection

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02B 1/10 G02B 1/10 Z F-term (Reference) 2H049 BA02 BB23 BB44 BB51 BB62 2K009 AA15 BB02 CC34 DD01 EE05 4F100 AK01A AR00B BA03 BA07 BA10B BA10C BA26 GB90 JK06B JK06C JL05 JL06B JL12B JL12C JL14B JL14C JN01A YY00A YY00B 4J004 AA04 AA05 AA07 AA09 AA10 AA11 CA03 CA04 CA06 CC03 DB02 FA04 4J040 CA001 CA011 CA081 DA021 DA051 DB051 DE031 DF001 DF011 DF031 EB132 EC002 EF262 EK001 JA09 JB09 KA16 LA06 LA10 MA05 MA10 NA17 PA23

Claims (8)

[Claims] 1. A pressure-sensitive adhesive film having a pressure-sensitive adhesive layer provided on one side of a plastic film and having a total light transmittance of 80% or more, and a peelable dirt on a surface (back surface) opposite to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film. A pressure-sensitive adhesive film for protecting an optical sheet before inspection, wherein a protective layer is laminated. 2. The pre-inspection optical sheet according to claim 1, wherein the antifouling layer is composed of an adhesive single-layer film or a multilayer film, and the multilayer film has adhesiveness on at least one side. Adhesive film for protection. 3. The adhesive strength of the antifouling layer to the back of the adhesive film is from 0.01 N / 25 mm to 1.0 N / 25 mm.
The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to claim 1 or 2, characterized in that: 4. The adhesive strength of the adhesive film to the optical sheet before inspection is larger than the adhesive strength of the stain prevention layer to the back of the adhesive film, from 0.01 N / 25 mm to 1.0 N.
The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to any one of claims 1 to 3, wherein the thickness is within a range of / 25 mm. 5. An adhesive layer is stuck on a glass surface,
The pre-inspection optical sheet according to any one of claims 1 to 4, wherein a change in water contact angle of the glass surface after treatment at 1 ° C for 1 minute and peeling is within 30 degrees with respect to an initial value. Adhesive film for protection. 6. The method according to claim 1, wherein a polyester film is attached to the surface of the pressure-sensitive adhesive layer as a separator.
6. The pressure-sensitive adhesive film for protecting an optical sheet before inspection according to claim 5. 7. A pre-inspection optical sheet with a protective film in which an adhesive layer is provided on one surface of a plastic film and an optical sheet before inspection is provided on the surface of the adhesive layer, the surface opposite to the adhesive layer of the adhesive film (the back surface). A) a pre-inspection optical sheet with a protective film, wherein a dirt preventing layer which is peeled off during a defect inspection of the pre-inspection optical sheet is laminated. 8. An adhesive sheet for protecting an optical sheet before inspection is attached to the surface of the optical sheet before inspection, and a stain prevention layer of the adhesive sheet for protecting optical sheet before inspection is peeled off immediately before performing a defect inspection of the optical sheet before inspection. A method for producing an optical sheet, comprising: performing a defect inspection in a state where an adhesive film is stuck to an optical sheet before inspection, and removing the adhesive film immediately before applying an adhesive or a hard coat agent.