Optical laminate

Abstract

To reduce a quantity of peeling electrification caused in peeling a surface protective film, further than the prior art.SOLUTION: An optical laminate 100 comprises a polarizer 102c, a protective layer stacked on the polarizer 102c, and a surface protective film 101 stacked on the protective layer. The protective layer has a surface treatment layer 102a on a surface of a surface protective film 101 side. The surface protective film 101 has at least two adhesive layers, and the surface protective film 101 is adhered on the surface treatment layer 102a through the at least two adhesive layers. At least one layer out of the at least two adhesive layers contains an antistatic agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical laminate. [Background technology]

[0002] A polarizing plate with a surface protective film is known as an optical laminate. Patent Document 1 describes a polarizing plate having a polarizer and a protective layer laminated on the polarizer. A surface protective film is laminated on the protective layer of the polarizing plate. The protective layer has a surface treatment layer on the surface facing the surface protective film. The surface protective film is attached to the surface treatment layer of the protective layer via an adhesive layer. When the polarizing plate is used, the surface protective film is peeled off and removed. Peeling off the surface protective film can sometimes cause peeling electrification. In Patent Document 1, peeling off electrification is reduced when peeling off the surface protective film by performing a surface activation treatment on the adhesive layer before adhering the surface protective film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-237489 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for further reduction in the amount of peeling electrification that occurs when peeling and removing a surface protection film. [Means for solving the problem]

[0005] The present invention includes the following inventions. [Invention 1] An optical laminate including a polarizer, a protective layer laminated on the polarizer, and a surface protective film laminated on the protective layer, the protective layer has a surface treatment layer on the surface facing the surface protection film, The surface protection film has at least two pressure-sensitive adhesive layers, the surface protection film is attached to the surface treatment layer via at least two of the pressure-sensitive adhesive layers, The optical laminate, wherein at least one of the at least two pressure-sensitive adhesive layers contains an antistatic agent.

[0006] [Invention 2] The optical laminate according to [Invention 1], wherein the total thickness of the at least two pressure-sensitive adhesive layers is 5 μm or more and 25 μm or less.

[0007] [Invention 3] The optical laminate according to [Invention 1] or [Invention 2], wherein the thickness of the pressure-sensitive adhesive layer on the surface treatment layer side of the at least two pressure-sensitive adhesive layers is 100 nm or more and 1 μm or less.

[0008] [Invention 4] The optical laminate according to any one of [Invention 1] to [Invention 3], wherein the adhesive layer on the surface treatment layer side of the at least two pressure-sensitive adhesive layers has a peel strength from the surface treatment layer of 0.04 N / 25 mm or more.

[0009] [Invention 5] The optical layered body according to any one of [Invention 1] to [Invention 4], wherein the surface treatment layer is an antifouling layer.

[0010] [Invention 6] The thickness of the polarizer is 15 μm or less, The optical layered body according to any one of [Invention 1] to [Invention 5], wherein the protective layer contains at least one resin selected from a cellulose-based resin, a polyester-based resin, and a cycloolefin-based resin.

[0011] [Invention 7] The optical laminate according to any one of [Invention 1] to [Invention 6], wherein a retardation film and a pressure-sensitive adhesive layer are laminated in this order on the surface of the polarizer opposite to the surface protective film side. [Effects of the Invention]

[0012] According to the optical laminate of the present invention, the amount of peeling charge that occurs when the surface protective film is peeled off can be further reduced. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the optical layered body of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The optical layered body of the present invention will be described below. <Polarizing plate> 1, the polarizing plate 102 includes a polarizer 102c and a protective layer laminated on the polarizer 102c. Specifically, the polarizing plate 102 includes a first protective layer 102b laminated on one surface of the polarizer 102c via an adhesive layer (not shown) as a protective layer. Furthermore, a surface protective film 101 is laminated on the first protective layer 102b.

[0015] That is, the optical laminate 100 includes a polarizer 102c, a first protective layer 102b laminated on the polarizer 102c, and a surface protective film 101 laminated on the first protective layer 102b.

[0016] 1, the first protective layer 102b has a surface treatment layer 102a on the surface facing the surface protection film 101. The polarizing plate 102 also has a second protective layer 102d as a protective layer laminated on the other surface of the polarizer 102c via an adhesive layer (not shown). That is, the optical laminate 100 includes the polarizer 102c, the first protective layer 102b, the surface protection film 101, and the second protective layer 102d. The polarizing plate 102 may have an adhesive layer 102e on the second protective layer 102d for bonding to a liquid crystal cell or the like.

[0017] <Polarizer> The polarizer is a polyvinyl alcohol resin film in which a dichroic dye is adsorbed and aligned. The polyvinyl alcohol resin may be, for example, a saponified polyvinyl acetate resin. The saponification degree of the polyvinyl acetate resin is preferably 85 mol% or more, more preferably 90 mol% or more, and even more preferably 99 mol% or more.

[0018] Examples of polyvinyl acetate resins that can be used include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate with other copolymerizable monomers. Examples of the copolymerizable other monomers include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids.

[0019] The degree of polymerization of the polyvinyl alcohol resin is preferably 1,000 or more and 10,000 or less, and more preferably 1,500 or more and 5,000 or less. The polyvinyl alcohol resin may be modified. Examples of the modified polyvinyl alcohol resin include polyvinyl formal, polyvinyl acetal, and polyvinyl butyral modified with aldehydes.

[0020] Examples of the dichroic dye include iodine and water-soluble dichroic dyes. The thickness of the polarizer is not particularly limited, but is, for example, 1 μm or more, preferably 5 μm or more, and more preferably 8 μm or more, and is, for example, 50 μm or less, preferably 30 μm or less, and more preferably 15 μm or less.

[0021] The thickness of the polarizer may be within any range that combines the above upper and lower limits. The thickness of the polarizer can be measured by observing the side surface or cross section of the polarizer using a known microscope. The thickness of items other than the polarizer can also be measured in a similar manner.

[0022] (Polarizer manufacturing method) A known method can be used to produce a polarizer, for example, by sequentially performing a swelling step, a dyeing step, a crosslinking step, a washing step, and a drying step using a polyvinyl alcohol-based resin film as a raw film.

[0023] The swelling step is a treatment step in which the raw film is immersed in a swelling liquid to swell it. The dyeing step is a treatment step in which the film after the swelling step is immersed in a dyeing solution containing a dichroic dye, thereby adsorbing and orienting the dichroic dye into the film. The crosslinking step is a treatment step in which a crosslinking liquid is brought into contact with the film to perform a crosslinking treatment. The crosslinking treatment can make the film water-resistant or adjust the hue (complementary color), for example. The crosslinking treatment may be performed multiple times. When performing the crosslinking treatment multiple times, the crosslinking treatment for the purpose of water resistance by crosslinking may be performed multiple times, or the crosslinking treatment for the purpose of hue adjustment may be performed multiple times. However, it is preferable to perform at least one crosslinking treatment for water resistance by crosslinking and at least one crosslinking treatment for hue adjustment, and it is more preferable to perform the crosslinking step for water resistance by crosslinking followed by the crosslinking step for hue adjustment. A uniaxial stretching treatment as a stretching step can be performed before, after, or during one or more of the swelling step, dyeing step, and crosslinking step. The washing step is a treatment step in which the film after the crosslinking step is brought into contact with a washing liquid to perform a washing treatment, and the drying step is a treatment step in which the film after the washing step is dried.

[0024] <Protective layer> 1, the first protective layer 102b and the second protective layer 102d as protective layers laminated on the polarizer 102c are not particularly limited, and various transparent protective films that can be used for the polarizing plate 102 can be used. Examples of materials that can be used to form the protective layers include thermoplastic resins that are excellent in transparency, mechanical strength, thermal stability, moisture blocking properties, isotropy, etc. Examples of thermoplastic resins include acetylcellulose ester-based resins such as triacetylcellulose and diacetylcellulose (hereinafter also referred to as cellulose-based resins); polyester-based resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polyethersulfone-based resins, polysulfone-based resins, polycarbonate-based resins; polyamide-based resins such as nylon and aromatic polyamide; polyimide-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; (meth)acrylic resins; cyclic polyolefin-based resins having a cyclo- or norbornene structure (hereinafter also referred to as cycloolefin-based resins); polyarylate-based resins; polystyrene-based resins; polyvinyl alcohol-based resins; and mixtures thereof. The protective layer may be a cured layer formed from a thermosetting resin or an ultraviolet-curable resin, such as a (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone resin. Among these, at least one resin selected from cellulose-based resins, polyester-based resins, and cycloolefin-based resins is preferred.

[0025] The first protective layer 102b and the second protective layer 102d may be made of the same material, or may be made of different materials selected from the above materials. The adhesive for laminating the polarizer 102c and the first protective layer 102b and the adhesive for laminating the polarizer 102c and the second protective layer 102d are not particularly limited, and for example, a known water-based adhesive can be used. The same material as that of the pressure-sensitive adhesive layer used to attach the surface protection film 101 described below can also be used.

[0026] Furthermore, an optically functional film may be laminated on the first protective layer 102b or the second protective layer 102d. Examples of optically functional films include a retardation film, an optical compensation film, and a diffusion film. These optically functional films may be used as protective layers. That is, the first protective layer 102b or the second protective layer 102d may be composed of an optically functional film.

[0027] Specific examples of the retardation film include a birefringent film made of a stretched film of a light-transmitting thermoplastic resin, and a film in which discotic or nematic liquid crystal is oriented and fixed.

[0028] (Surface treatment layer) 1, the first protective layer 102b has a surface treatment layer 102a on the surface facing the surface protection film 101. The surface treatment layer 102a is not particularly limited, and any known surface treatment layer can be used. Examples of known surface treatment layers include an antifouling layer, a hard coat layer, an antiglare layer, an antireflection layer, a low-reflection layer, and an antistatic layer.

[0029] The antifouling layer has a function of preventing the polarizer from being soiled. The hard coat layer has a function of preventing the polarizer from being scratched. The antiglare layer has a function of preventing external light from being reflected on the surface of the polarizer, thereby preventing the visibility of transmitted light from the polarizer from being impaired. The antireflection layer has a function of preventing external light from being reflected on the surface of the polarizer. The low-reflection layer has a function of reducing the reflection of external light on the surface of the polarizer. The antistatic layer has a function of preventing dust from adhering to the polarizer due to the charge on the polarizer itself.

[0030] The first protective layer 102b may have one of the above surface treatment layers alone or a suitable combination of two or more of them. Among these, it is preferable that the first protective layer 102b has an antifouling layer.

[0031] The method for forming the antifouling layer is not particularly limited, and known methods can be used. For example, the antifouling layer can be formed by physical vapor deposition methods such as vapor deposition and sputtering, chemical vapor deposition methods, or wet coating methods. The material used to form the antifouling layer is not particularly limited, and a fluorine-based treatment agent or a silicon-based treatment agent can be used. Specific examples of fluorine-based treatment agents include fluorine-containing organic compounds such as fluorocarbons and perfluorosilanes, and polymer compounds thereof.

[0032] The thickness of the surface treatment layer 102a is not particularly limited, but is preferably 1 nm or more and 50 nm or less, and more preferably 3 nm or more and 35 nm or less. <Surface protection film> 1, the surface protection film 101 has a base film 101a and two adhesive layers laminated on the base film 101a: a first adhesive layer 101b and a second adhesive layer 101c. The surface protection film 101 is attached to the surface treatment layer 102a of the first protection layer 102b via the two adhesive layers. Of the two adhesive layers, the first adhesive layer 101b, which is not in contact with the surface treatment layer 102a, contains an antistatic agent, while the second adhesive layer 101c, which is in contact with the surface treatment layer 102a, does not contain an antistatic agent.

[0033] (Base film) The substrate film is not particularly limited, and various substrate films that can be used for optical laminates can be used. Specific examples of materials constituting the substrate film include polyester films such as polyethylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and polybutylene terephthalate, polycarbonate films, polysulfone films, polyamide films, polyolefin films, and liquid crystal polymer films.

[0034] Among the above, polyester films are preferred because they can impart sufficient strength to the substrate film to protect the polarizing plate surface, and have optical properties such as being colorless and having excellent transparency and facilitating inspection. In particular, polyethylene terephthalate films are more preferred because they are relatively inexpensive and easily available.

[0035] The substrate film may be a non-stretched film or may be uniaxially or biaxially stretched. The thickness of the substrate film is not particularly limited, but is preferably about 6 μm or more and 100 μm or less, more preferably 20 μm or more and 50 μm or less. If the thickness is less than 6 μm, the surface protection film may not be able to have sufficient strength. If the thickness of the substrate film is greater than 100 μm, the handling property tends to be poor.

[0036] The substrate film may contain additives such as various stabilizers, ultraviolet absorbers, lubricants, pigments, antioxidants, and plasticizers, as required. (Adhesive layer) 1, of the two pressure-sensitive adhesive layers, the pressure-sensitive adhesive layer on the surface treatment layer 102a side of the first protective layer 102b is referred to as the second pressure-sensitive adhesive layer 101c. That is, the layer attached to the surface treatment layer 102a of the first protective layer 102b is referred to as the second pressure-sensitive adhesive layer 101c. Furthermore, the layer attached to the second pressure-sensitive adhesive layer 101c is referred to as the first pressure-sensitive adhesive layer 101b. The first pressure-sensitive adhesive layer 101b and the second pressure-sensitive adhesive layer 101c are not particularly limited, and various pressure-sensitive adhesive layers that can be used in the optical laminate 100 can be used.

[0037] Specific examples of the adhesive constituting the adhesive layer include acrylic adhesives having an acrylic polymer as the base polymer, as well as adhesives based on natural or synthetic rubber, silicone, etc. Among these, acrylic adhesives having an acrylic polymer having a weight-average molecular weight of about 200,000 to 2,500,000 as the base polymer are preferred due to their excellent transparency.

[0038] The pressure-sensitive adhesive layer may contain a crosslinking agent. Examples of crosslinking agents include polyisocyanate compounds, epoxy compounds, and aziridine compounds. In addition, the pressure-sensitive adhesive layer may contain various additives such as photopolymerization initiators, leveling agents, antioxidants, and light stabilizers.

[0039] The first adhesive layer 101b and the second adhesive layer 101c may be made of the same material, or may be made of different materials selected from the above materials. The thickness of the pressure-sensitive adhesive layer is not particularly limited. The total thickness of the first pressure-sensitive adhesive layer 101b and the second pressure-sensitive adhesive layer 101c is preferably 5 μm or more, more preferably 10 μm or more. Also, it is preferably 25 μm or less, more preferably 20 μm or less, and even more preferably 15 μm or less.

[0040] When the thickness of the pressure-sensitive adhesive layer is within the above range, the pressure-sensitive adhesive layer can be made thin and the processability can be improved. The thickness of the first pressure-sensitive adhesive layer 101b is not particularly limited, but is preferably 4 μm or more, more preferably 8 μm or more, and is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 14 μm or less.

[0041] When the thickness of first pressure-sensitive adhesive layer 101b is within the above range, first pressure-sensitive adhesive layer 101b can be made thinner and an antistatic agent can be easily incorporated into first pressure-sensitive adhesive layer 101b. The thickness of the second pressure-sensitive adhesive layer 101c is not particularly limited, but is preferably 100 nm or more, more preferably 500 nm or more, and is preferably 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

[0042] When the thickness of the second pressure-sensitive adhesive layer 101c is within the above range, adhesion of the second pressure-sensitive adhesive layer 101c to the surface treatment layer 102a of the first protective layer 102b can be easily suppressed when the surface protection film 101 is peeled off from the optical laminate 100. In other words, the antifouling properties of the optical laminate 100 can be further improved.

[0043] The total thickness of the first adhesive layer 101b and the second adhesive layer 101c, the thickness of the first adhesive layer 101b, and the thickness of the second adhesive layer 101c may fall within any range combining the above upper and lower limits.

[0044] The peel strength of the second adhesive layer 101c from the surface treatment layer 102a of the first protective layer 102b is not particularly limited, but is preferably 0.04 N / 25 mm or more. When the peel strength of the second adhesive layer 101c is 0.04 N / 25 mm or more, unintentional peeling of the second adhesive layer 101c can be suitably prevented. The method for measuring the peel strength will be described later.

[0045] (antistatic agent) Among the adhesive layers, the first adhesive layer 101b contains an antistatic agent, and the second adhesive layer 101c does not contain an antistatic agent. When the adhesive layer contains an antistatic agent, the amount of peeling charge generated when peeling off the surface protection film 101 can be further reduced.

[0046] The absolute value of the peeling charge generated when peeling off surface protective film 101 is preferably less than 1.2 kV, more preferably 1.0 kV or less, and even more preferably 0.8 kV or less.

[0047] Any known antistatic agent can be used without any particular limitation. Preferred antistatic agents include ionic antistatic agents, conductive polymers, various surfactants (cationic, anionic and amphoteric surfactants), metals and metal oxides, which have good compatibility with the acrylic pressure-sensitive adhesive preferably used in the present invention.

[0048] Specific examples of ionic antistatic agents include cationic antistatic agents such as quaternary ammonium salts, phosphonium salts, and sulfonium salts, anionic antistatic agents such as carboxylic acid, sulfonate, sulfate, phosphate, and phosphite, and zwitterionic antistatic agents such as sulfobetaines, alkylbetaines, and alkylimidazolium betaines. It is also possible to use nonionic antistatic agents such as polyhydric alcohol derivatives, β-cyclodextrin clathrate compounds, sorbitan fatty acid monoesters, sorbitan fatty acid diesters, polyalkylene oxide derivatives, and amine oxides.

[0049] Specific examples of conductive polymers include polyaniline, polythiophene, polypyrrole, polyquinoxaline, etc. Among these, polyaniline, polythiophene, etc. are preferred because they can be suitably used as ultraviolet-curable conductive polymers, water-soluble conductive polymers, or water-dispersible conductive polymers.

[0050] The amount of antistatic agent added is preferably 1 part by mass or more and 30 parts by mass or less, and more preferably 5 parts by mass or more and 20 parts by mass or less, per 100 parts by mass of the base polymer in the first pressure-sensitive adhesive layer 101b. If the amount of antistatic agent added is less than 1 part by mass per 100 parts by mass of the base polymer, the effect of adding the antistatic agent to reduce the amount of peel electrification tends to be insufficient. On the other hand, if the amount of antistatic agent added is more than 30 parts by mass per 100 parts by mass of the base polymer, compatibility with the base polymer becomes poor, making it difficult for the antistatic agent to be uniformly dispersed, and transparency tends to be poor.

[0051] <Optical laminate> 1, a surface protection film 101 is laminated on a surface treatment layer 102a of a first protective layer 102b of a polarizing plate 102, thereby forming an optical laminate 100. In the optical laminate 100, of the two pressure-sensitive adhesive layers of the surface protection film 101, the second pressure-sensitive adhesive layer 101c is attached to the surface treatment layer 102a of the first protective layer 102b of the polarizing plate 102. In addition, the first pressure-sensitive adhesive layer 101b is attached between the base film 101a and the second pressure-sensitive adhesive layer 101c of the surface protection film 101. The first pressure-sensitive adhesive layer 101b contains an antistatic agent.

[0052] Since the first pressure-sensitive adhesive layer 101b contains an antistatic agent, the amount of peeling charge can be further reduced when the surface protection film 101 is peeled off from the optical laminate 100. Furthermore, since the surface protection film 101 has two pressure-sensitive adhesive layers, adhesion of the pressure-sensitive adhesive layers to the surface treatment layer 102a can be more easily suppressed when the surface protection film 101 is peeled off from the optical laminate 100. In other words, the antifouling properties can be improved compared to an embodiment having a single pressure-sensitive adhesive layer.

[0053] The use of the optical laminate 100 is not particularly limited, and it can be used in known image display devices. Examples of known image display devices include organic electroluminescence (also referred to as organic EL) display devices, inorganic electroluminescence (also referred to as inorganic EL) display devices, liquid crystal display devices, and electroluminescence display devices.

[0054] The image display device may have a touch panel function. When the optical laminate has a front panel, it can be arranged on the image display device so that the front panel forms the outermost surface on the viewing side. When the optical laminate is bendable, the image display device on which the optical laminate is arranged is preferably a flexible display.

[0055] The image display device can be used as mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic billboards, measuring instruments and gauges, office equipment, medical equipment, computing equipment, and the like.

[0056] <Example of change> This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0057] In this embodiment, of the two adhesive layers of the surface protection film 101, only the first adhesive layer 101b contains an antistatic agent, but this is not limited to this. Only the second adhesive layer 101c may contain an antistatic agent, or both the first adhesive layer 101b and the second adhesive layer 101c may contain an antistatic agent.

[0058] The surface protection film 101 may have two or more adhesive layers. At least one of the two or more adhesive layers may contain an antistatic agent. The total thickness of the first adhesive layer 101b and the second adhesive layer 101c may be less than 5 μm or more than 25 μm.

[0059] The thickness of the second adhesive layer 101c may be less than 100 nm or more than 1 μm. The peeling force of the second adhesive layer 101c from the surface treatment layer 102a of the first protective layer 102b may be less than 0.04 N / 25 mm.

[0060] The thickness of the polarizer 102c may be greater than 15 μm. In the present embodiment, the optical laminate 100 has a retardation film as the second protective layer 102d and a pressure-sensitive adhesive layer 102e laminated in this order on the surface of the polarizer 102c opposite to the surface protection film 101, but is not limited to this. The retardation film and the pressure-sensitive adhesive layer 102e may be omitted. [Example]

[0061] The optical laminate will be described in more detail below based on the examples described below, but the optical laminate is not limited to the configurations described in the examples. Example 1 (Preparation of polarizing plate) A polyvinyl alcohol film with a thickness of approximately 75 μm was dyed and stretched in an aqueous solution containing iodine and potassium iodide. It was then crosslinked in an aqueous solution containing boric acid and potassium iodide, washed with water, and dried to obtain polarizer 102c. Polarizer 102c had a thickness of 28 μm.

[0062] Separately, a triacetyl cellulose film was prepared. The triacetyl cellulose film had an antifouling layer on one surface as the surface treatment layer 102a. Specifically, one surface of the triacetyl cellulose film was coated with a fluorine-based treatment agent by a wet coating method to form an antifouling layer. The average thickness of the antifouling layer was 100 nm. The triacetyl cellulose film was attached to the surface of the polarizer 102c using a known aqueous adhesive so that the antifouling layer was on the outermost surface, thereby forming the first protective layer 102b.

[0063] Furthermore, a retardation film made of a norbornene-based resin was prepared and attached to the surface of the polarizer 102c opposite to the first protective layer 102b using a known water-based adhesive to form a second protective layer 102d.

[0064] Furthermore, a sheet-shaped adhesive was prepared by forming an approximately 25 μm thick acrylic adhesive layer on the release-treated surface of a release film that had been treated with a silicone release agent. The adhesive layer side of the sheet-shaped adhesive was attached to the retardation film, and the adhesive layer 102e was laminated on the retardation film. A polarizing plate 102 was produced using the above procedure.

[0065] (Production of optical laminate) 1, a surface protection film 101 was prepared in which two adhesive layers were formed on a base film 101a made of a 38 μm-thick polyethylene terephthalate film. Specifically, the surface protection film 101 was prepared in which an acrylic adhesive layer as a first adhesive layer 101b and an acrylic adhesive layer as a second adhesive layer 101c were laminated in this order on one surface of the base film 101a.

[0066] The first adhesive layer 101b contains a conductive polymer as an antistatic agent, and the amount of the antistatic agent added to the first adhesive layer 101b was 20 parts by mass relative to 100 parts by mass of the acrylic resin as the base polymer.

[0067] Furthermore, in surface protection film 101, a release film that had been subjected to a release treatment using a silicone-based release agent was laminated on the surface of second pressure-sensitive adhesive layer 101c opposite to the first pressure-sensitive adhesive layer 101b side.

[0068] After removing the release film from the surface protective film 101, the exposed second pressure-sensitive adhesive layer 101c was attached to the surface treatment layer 102a on the first protective layer 102b of the polarizing plate 102 to produce an optical laminate 100, which is a polarizing plate 102 with a surface protective film 101. In the optical laminate 100, the first pressure-sensitive adhesive layer 101b had a thickness of 13 μm, and the second pressure-sensitive adhesive layer 101c had a thickness of 0.9 μm.

[0069] <Example 2> An optical laminate 100 was produced in the same manner as in Example 1, except that the thickness of the second pressure-sensitive adhesive layer 101c was set to 2 μm.

[0070] <Comparative Example 1> An optical laminate was prepared in the same manner as in Example 1, except that the second adhesive layer 101c was omitted and the first adhesive layer 101b of the surface protection film 101 was bonded to the surface treatment layer 102a on the first protective layer 102b of the polarizing plate 102.

[0071] <Evaluation test> The optical laminates of each of the Examples and Comparative Examples were evaluated for peel charge amount, peel strength, and antifouling performance. The evaluation methods and evaluation results are shown below.

[0072] (1) Peeling charge The optical laminate was placed on a glass substrate with the pressure-sensitive adhesive layer 102e on the retardation film side. After bonding the two together using a hand roller, they were heated and pressurized for 15 minutes at a temperature of 50°C and a pressure of 490 MPa (gauge pressure) to adhere the optical laminate to the glass substrate. After that, they were kept in an environment of 23°C and 55% relative humidity for 24 hours to prepare an evaluation sample.

[0073] Next, this evaluation sample was fixed to a high-speed peeling device (K Printing Proofer, manufactured by RK Print Coat Instruments), and the surface protection film 101 was then peeled off at a peel angle of approximately 160° and a peel speed of 16 m / min in an environment of 23°C temperature and 55% relative humidity. The amount of peel charge generated at this time was measured using a static electricity measuring device (FM300, manufactured by SIMCO) placed at a height of 25 mm from the surface treatment layer 102a of the polarizing plate 102. The amount of peel charge was evaluated according to the following criteria.

[0074] Evaluation criteria for peeling charge amount A (Acceptable): The absolute value of the measured peel charge is less than 1.2 kV. B (unacceptable): The absolute value of the measured peel charge is 1.2 kV or more.

[0075] (2) Peeling force The optical laminate was cut into a width of 25 mm, and the pressure-sensitive adhesive layer 102e on the retardation film was placed on a glass substrate. After laminating the two together using a hand roller, the resultant was kept in an environment of 23°C and 55% relative humidity for 24 hours to prepare a sample for evaluation.

[0076] Next, while the polarizing plate 102 side of this evaluation sample was fixed, the surface protection film 101 was peeled from the polarizing plate 102 using an AGS-D model testing machine manufactured by Shimadzu Corporation under conditions of a peel angle of 180° and a peel speed of 300 mm / min. The peel force (unit: N / 25 mm) at this time was measured. The peel force was evaluated according to the following criteria.

[0077] Peel strength evaluation criteria A (Acceptable): Peeling force is 0.04N / 25mm or more. B (unacceptable): Peeling force is less than 0.04 N / 25 mm.

[0078] (3) Antifouling performance After the optical laminate was produced, it was left to stand for one day to prepare a sample for evaluation. After peeling off the surface protection film 101 of the evaluation sample with fingers, the surface treatment layer 102a of the polarizing plate 102 was visually observed. The surface of the surface treatment layer 102a was also touched with a finger to check for the presence or absence of adhesive component residue. If adhesive component residue was present, it felt sticky to the touch. The antifouling performance was evaluated according to the following criteria.

[0079] ·Evaluation criteria for antifouling performance 2A (Good): No discoloration on the surface and no adhesive residue is found. A (Acceptable): There is some discoloration on the surface, but no adhesive residue is found.

[0080] B (Not acceptable): When discoloration is observed on the surface and adhesive residue is found. Table 1 shows the evaluation results of peeling charge amount, peeling force, and antifouling performance.

[0081] [Table 1] As can be seen from Table 1, the optical laminate of Comparative Example 1 had peel strength and antifouling performance both rated "A (acceptable)" or higher, but the peel charge was rated "B (unacceptable)." In contrast, the optical laminates of Examples 1 and 2 were rated "A (acceptable)" or higher in all of peel charge, peel strength, and antifouling performance. The optical laminates of Examples 1 and 2 have a small peel charge, which makes it easier to prevent circuit damage when the optical laminate is used in a liquid crystal display device or the like. Furthermore, the small peel charge makes it less likely to affect the alignment of the liquid crystal, making it easier to prevent display unevenness. [Explanation of symbols]

[0082] 100...Optical laminate 101...Surface protection film 101a...Base film 101b...first adhesive layer 101c...Second adhesive layer 102...Polarizing plate 102a...Surface treatment layer 102b…1st protective layer 102c...Polarizer 102d…Second protective layer 102e...Adhesive layer

Claims

1. An optical laminate including a polarizer, a protective layer laminated on the polarizer, and a surface protective film laminated on the protective layer, the protective layer has a surface treatment layer on the surface facing the surface protection film, The surface protection film has at least two pressure-sensitive adhesive layers, the surface protection film is attached to the surface treatment layer via at least two pressure-sensitive adhesive layers, An optical laminate, wherein at least one of the at least two pressure-sensitive adhesive layers contains an antistatic agent.

2. 2. The optical laminate according to claim 1, wherein the total thickness of the at least two pressure-sensitive adhesive layers is 5 μm or more and 25 μm or less.

3. 2. The optical laminate according to claim 1, wherein the thickness of the pressure-sensitive adhesive layer on the surface treatment layer side of the at least two pressure-sensitive adhesive layers is 100 nm or more and 1 μm or less.

4. 2. The optical laminate according to claim 1, wherein the pressure-sensitive adhesive layer on the surface treatment layer side of the at least two pressure-sensitive adhesive layers has a peel strength from the surface treatment layer of 0.04 N / 25 mm or more.

5. The optical laminate according to claim 1 , wherein the surface treatment layer is an antifouling layer.

6. The thickness of the polarizer is 15 μm or less, The optical laminate according to claim 1 , wherein the protective layer contains at least one resin selected from the group consisting of a cellulose-based resin, a polyester-based resin, and a cycloolefin-based resin.

7. The optical laminate according to claim 1 , further comprising a retardation film and a pressure-sensitive adhesive layer laminated in this order on the surface of the polarizer opposite to the surface protective film.

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