JP3425775B2 - Surface protection film for optical components - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member, such as a polarizing plate, a retardation plate, or a liquid crystal display panel, which is attached to at least one surface of the optical member. The present invention relates to a surface protection film for protecting the surface. As is well known, a liquid crystal cell has a structure in which liquid crystal is sealed between two substrates. The LCD panel is
Typically, the polarizing plate on one side of the liquid crystal cell, the other surface is produced by laminating a polarizing plate via a phase difference plate. The phase difference plate may be omitted, or a compensation liquid crystal cell may be used instead of the phase difference plate. Lamination of a polarizing plate or a retardation plate is usually performed by attaching a polarizing plate with an adhesive layer or a retardation plate with an adhesive layer to an object. As the above polarizing plate or retardation plate,
What has laminated | stacked the cellulose triacetate film as a protective plate on both sides of a polarizing element film or a retardation element film is used widely. However, since the cellulose triacetate film is inferior in scratch resistance and water resistance, the outermost layer is covered with a protective film during handling of a polarizing plate or a retardation plate or after manufacturing a liquid crystal display panel. The optical members are prevented from being damaged during the distribution process. The installation of a protective film is also necessary to prevent dust from adhering. Then, the protective film is peeled off when the retardation plate is actually attached to the liquid crystal cell, or the protective film on the polarizing plate is peeled off when the liquid crystal display panel to which the polarizing plate is attached is used. Conventionally, as the above protective film, a thermocompression-bonding type such as a polyethylene film or an ethylene-vinyl acetate copolymer film, and a pressure-sensitive adhesive type such as a polyester film having a weak adhesive layer have been used. I have. The present applicant has also filed the following application as a protective film for protecting the surface of a polarizing plate by attaching the polarizing plate on a liquid crystal display panel. [0007] That is, JP-A-4-31442 discloses a resin or plasticized resin having a glass transition point of 50 ° C. or lower, which has an adhesive property to a polarizing plate and has a sticking property to a polarizing plate. The surface has a surface smoothness of 0.1 μmm or less, a retardation value of 30 nm or less, and a visible light transmittance of 75%.
A surface protective film made of the above-described optically isotropic film is shown. Japanese Patent Application Laid-Open No. Hei 4-30120 has a layer structure of an optically isotropic substrate film layer / an optically isotropic adhesive resin layer, has a visible light transmittance of 75% or more, and A surface protection film comprising a photoisotropic laminated film having a surface smoothness of the isotropic adhesive resin layer of 0.1 μmm or less is shown. Japanese Patent Application Laid-Open No. 4-32805 discloses a light-transmitting material having a layer structure of a scratch-resistant light isotropic material layer / a light isotropic substrate film layer / a light isotropic adhesive resin layer and a visible light transmittance. Is 75% or more.
Here, the scratch-resistant photoisotropic material layer includes a cured thermosetting resin layer, a cured ultraviolet curable resin layer, an inorganic layer (such as a silicon dioxide layer), and the like. [0010] The manufactured liquid crystal display panel is usually inspected in a timely manner in order to evaluate the display performance, hue, contrast and the like. However, protective films that have been widely used in the past hinder inspections involving such optical evaluations.Therefore, prior to inspections, these protective films were once peeled off, and a new protective film was applied again after the inspections were completed. Fixing is done. The re-attachment is performed with a new protective film because the protective film does not have re-adhesive properties, or the beautifulness is impaired when re-applying even if it can be re-applied. The above-described peeling and re-attachment of the protective film for the inspection requires two steps in the process, which should be a great obstacle in this field where cost reduction is pursued to the utmost. However, from the recognition that protective films are originally such, no measures have been taken to improve them at present. On the other hand, the above-mentioned Japanese Patent Application Laid-Open Nos. Hei 4-31442 and Hei 4-30120 filed by the applicant of the present invention.
The protective film disclosed in Japanese Patent Application Laid-Open No. 4-32805 and Japanese Patent Application Laid-Open No. 4-32805 has a great advantage that peeling is not required at the time of inspection since it has optical isotropy. However, the protective film disclosed in JP-A-4-31442 is not sufficient in terms of sticking properties and scratch resistance, and the protective film described in JP-A-4-30120 is not sufficient in terms of scratch resistance. There is a limit. In this respect, the protective film disclosed in Japanese Patent Application Laid-Open No. 4-32805 has a scratch-resistant photo-isotropic material layer, so that the problem of scratch resistance has been solved.
Since the lower layer provided with the scratch-resistant light-isotropic material layer is a soft layer, the scratch-resistance and surface hardness are not necessarily sufficiently improved by the installation of the scratch-resistant light-isotropic material layer. Noticed something hard to say.
Further, when using a heat-curable resin cured product layer or an ultraviolet-curable resin cured product layer as the scratch-resistant photoisotropic material layer, there is a restriction on the selection of a resin liquid that does not affect the photoisotropic substrate film layer. In some cases, it is not always possible to select a film having optimal film properties, and furthermore, there are problems or problems such as poor adhesiveness with the optically isotropic substrate film layer and a desire to further increase the air permeability. . When an inorganic layer such as a silicon dioxide layer is used as the scratch-resistant photoisotropic material layer, a trouble such as a crack may occur due to bending during use. Under such a background, the present invention does not require peeling at the time of inspection, further improves scratch resistance and surface hardness, and includes a specific metal oxide layer. An object of the present invention is to provide a surface protection film for an optical member that does not cause a problem such as cracking and does not impose a burden on cost. [0016] The surface protective film of the optical member of the present invention comprises a polarizing element film or a retardation element film.
A polarizing plate or a retardation plate having a configuration in which a protective plate is laminated on one side , or a polarizing plate with the protective plate or
The liquid crystal display panel having a structure in which a phase difference plate is laminated on the surface side, in optical selected from members (2), for optical
A protective film (1) for protecting the surface of the optical member (2) by adhering to at least one surface of the member (2) from above the protective plate , wherein the protective film (1)
Is provided with an adhesive resin layer (12) on one surface of a single-layer or multi-layer optically isotropic base sheet (11), and a SiO _x (1 <x <2) layer (13) on the other surface. Through the curable resin cured material layer (1
It is characterized by having a layer configuration provided with 4). Hereinafter, the present invention will be described in detail. In this specification, the terms film, sheet, and plate are used, but there is no special distinction between them. [0018] an optical member (2) is a polarizing plate, a retardation plate or a liquid crystal display panel and the like. Among these, polarizing plates are made of vinyl alcohol polymer / iodine, vinyl alcohol polymer / dichroic dye, vinyl alcohol polymer / polyene, polyvinyl halide / polyene, polyacrylonitrile /
It is formed by laminating protective plates such as a cellulose triacetate film and a cellulose butyrate acetate film on both sides of a polarizing element film such as polyene. As the protective plate, in addition to a cellulose triacetate film and a cellulose butyrate acetate film, a polycarbonate film, a polymethyl methacrylate film, a polyvinyl chloride film, an ethylene-vinyl alcohol copolymer film, a polyamide film, a polystyrene film, and the like can also be used. However, it is practically limited to a cellulose triacetate film or a cellulose butyrate acetate film, especially a cellulose triacetate film. The retardation plate is provided on both sides of a retardation film composed of a polymer film uniaxially stretched (or biaxially stretched in some cases),
It is composed of laminated protective plates such as a cellulose triacetate film and a cellulose butyrate acetate film. Some polymer films such as amino acid resins have a retardation function without being uniaxially stretched, and thus such a polymer film can be used as a retardation film. The liquid crystal display panel is a combination of a liquid crystal cell and a polarizing plate or a retardation plate, and the outermost layer is a polarizing plate. A protective film (1) is adhered to at least one surface of the optical member (2). In the present invention, the protective film (1) is a single-layer or multi-layer optical isotropy. An adhesive resin layer (12) is provided on one side of a functional base sheet (11), and a curable resin layer (14) is provided on the other side via an SiO _x (1 <x <2) layer (13). ) Is used. Here, as the optically isotropic base sheet (11), a film having a necessary mechanical strength, for example, a rigid polyvinyl chloride film, a polyvinylidene chloride film, a polycarbonate film, a polystyrene film, a polyester film, a polysulfone film , Poly-4-methylpentene film, polyphenylene oxide film, polyethersulfone film, polyarylate film, polyvinyl alcohol film,
An ethylene-vinyl alcohol copolymer film, a cellulose-based polymer film, or the like is used. The optically isotropic base sheet (11) may be a single layer or a multilayer. Since the base sheet (11) is required to have optical isotropy, it is a film having a retardation value of 30 nm or less, especially 20 nm or less, and having a visible light transmittance of 75% or more. Is used. Such an optically isotropic base sheet (11) can be obtained by forming a film by a casting method. However, if the retardation value and the visible light transmittance satisfy the above conditions, other methods such as an extrusion method may be used. Molding method can be employed. This optically isotropic base sheet
The thickness of (11) is suitably about 5 to 200 μm. As the adhesive resin layer (12), an optical member
(2) a layer having an adhesive property, for example, a heat-sensitive adhesive resin layer of polyester, acrylic, polyolefin, polyamide or the like; acrylic, polyester, urethane, polyether, rubber, etc. Pressure-sensitive adhesive resin layer; a resin having a functional group such as a saturated polyester resin, a polyurethane resin, a polybutadiene polyol, a polyolefin polyol, and a functional group-containing acrylic copolymer is mixed with a curing agent to form a film, and partially crosslinked or non-crosslinked. A completely crosslinked film; a soft polyvinyl chloride film in which a plasticizer is blended with, for example, 20% by weight or more of polyvinyl chloride; a saturated polyester resin film; an acrylic copolymer film; butyl rubber, urethane rubber, butadiene rubber (polybutadiene rubber, Styrene-butadiene rubber, styrene-butadiene-styrene Film obtained by forming a synthetic rubber such as unblock copolymer) or styrene-isoprene-styrene rubber; obtained by forming a polyolefin-based resin such as low molecular weight polyethylene, atactic polypropylene, and chlorinated polypropylene. And a film obtained by forming an ethylene-based copolymer such as an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, and an ethylene-acrylate copolymer. This adhesive resin layer (12) also needs to have optical isotropy. When the rework property is required, the adhesive resin layer (12) is selected to have a peeling property, and when the permanent adhesion is required, a strong adhesive force or adhesive force is obtained. Choose one. The thickness of the adhesive resin layer (12) is
It is often set to about 1 to 50 μm. As the SiO _x layer (13) , _x of SiO x is 1 <x in consideration of cost, transparency, adhesion to the optically isotropic base sheet (11), and non-coloring. <
2) is used. Silicon dioxide represented by SiO ₂ is, SiO _x (provided that, 1 <x <2) insufficient properties if Hisure to. As the curable resin cured product layer (14), a heat-curable resin cured product layer (phenoxy ether type crosslinkable resin,
Epoxy resin, acrylic resin, acrylic silicone resin, silicone resin, melamine resin, phenolic resin, urethane resin, rubber resin, etc.), UV cured resin cured material layer (phosphazene resin, acrylic resin, etc.) And so on. The thickness is often about 0.5 to 50 μm. This cured resin layer (14) also needs to have optical isotropy. The overall retardation value and visible light transmittance of the protective film (1) having the above-mentioned layer constitution are also:
Care should be taken that they are respectively 30 nm or less and 75% or less. As described above, the protective film (1) is composed of the adhesive resin layer (12) / optically isotropic base sheet (11) / SiO _x layer (1).
3) / The cured resin layer (14) has a layer structure, but is usually handled in a rolled state, so when using an adhesive resin layer (12) having adhesiveness, , Curable resin layer (1) which comes into contact with the adhesive resin layer (12) during winding.
4) back-treating with a release agent such as a silicone-based release agent, a fluororesin-based release agent, or a compound having a long-chain alkyl group to make the adhesive resin layer (12) releasable or cured. The cured cured resin layer (14) itself is constituted by a resin layer having releasability (for example, an acrylic silicone resin layer), or a releasable sheet is further provided on the adhesive resin layer (12). The release sheet is prepared by treating the surface of a paper or plastic film with a silicone release agent or other release agent, blending a film or sheet having a release property with itself, or a release agent. A molded film or sheet, a plastic film or sheet obtained by graft-polymerizing an organopolysiloxane and a polyolefin resin, or the like is used. The thickness of the peelable sheet is often about 12 to 250 μm. A liquid crystal display panel typically includes a polarizing plate /
It has a configuration of retardation plate / liquid crystal cell / polarizing plate. The phase difference plate may be omitted, or a compensation liquid crystal cell may be used instead of the phase difference plate. Among them, the liquid crystal cell has two substrates with transparent electrodes such as ITO opposed to each other via a spacer,
The liquid crystal is sealed in the gap. Usually, an orientation film is also provided. In the present invention, the protective film (1) comprises an adhesive resin layer (12) / optically isotropic base sheet (11) / SiO _x layer (13).
/ Cured resin cured product layer (14). The protective film (1) has the adhesive resin layer (12) side adhered to the surface of an optical member (2) such as a polarizing plate or a retardation plate. This protective film (1) is over the polarizer, which is the outermost layer after being assembled on the liquid crystal display panel.
Is often attached. When the adhesive resin layer (12) side is covered with a peelable sheet, this peelable sheet is peeled and removed before sticking. The SiO _x layer (13) is formed on the optically isotropic base sheet (1).
To 1), properties such as scratch resistance, surface hardness, solvent resistance, adhesion, heat resistance, moisture resistance, and air resistance are imparted. Si
Since the O _x layer (13) is sandwiched between the optically isotropic base sheet (11) and the cured resin layer (14), even if a bending force is applied during the handling of the protective film (1), SiO _x
There is no trouble such as cracking in the layer (13). Si
Since the _Ox layer (13) has solvent resistance, there is no problem even if a material that affects the optically isotropic base sheet (11) is used in forming the curable resin cured material layer (14) formed thereon. Does not occur. The curable resin cured material layer (14) constituting the outermost layer plays a role in further improving the scratch resistance and the surface hardness in cooperation with the lower SiO _x layer (13). That is, the curable resin cured layer on a lower rigid SiO _x layer (13) (1
Since 4) is arranged, improvement in scratch resistance and surface hardness can be achieved. As described above, the drawbacks of each layer constituting the protective film (1) are skillfully avoided, and only the advantages of each layer appear, so that the protective film (1) has an optimum suitability as a surface protective film as a whole. In the case of a liquid crystal display panel, display capability, hue,
When conducting tests for evaluation of contrast etc., it is not necessary to peel off the attached protective film (1),
These tests may be performed with the protective film (1) attached. When the protective film (1) is required to have a rework property, for example, the protective film (1) is peeled off before the liquid crystal display panel is actually used. On the other hand, when reworkability is not required, the protective film (1) is used for actual use while being permanently bonded. Next, the present invention will be further described with reference to examples. Hereinafter, "parts" refers to parts by weight. Example 1 FIG. 1 is a sectional view showing an example of the surface protective film of the present invention. (11) is a polycarbonate film as an example of an optically isotropic base sheet, which is manufactured by a casting method. The retardation value is 5 nm, the visible light transmittance is 90%, and the thickness is 30 μm. (13) is a SiO _x layer having a thickness of 1 formed on one surface of the optically isotropic base sheet (11) by vapor deposition.
000 Å of SiO _x , where x is between 1 and 2. The adhesion of the SiO _x layer (13) to the optically isotropic base sheet (11)
(11) face the written not provided an anchor coating layer
Not so good. Reference numeral (14) denotes a cured resin layer, and an epoxy acrylic resin manufactured by Nippon Steel Chemical Co., Ltd. is placed on the optically isotropic base sheet (11) with the SiO _x layer (13) obtained above. An ultraviolet curable resin composition obtained by adding 1 part of benzophenone to 100 parts of “V-254PA” is applied to a thickness of about 5 μm,
It is formed by irradiating ultraviolet rays with an ultraviolet lamp under the conditions of 120 W / cm, one lamp and three seconds. (12) is an adhesive resin layer, which has a layer structure of the photoisotropic base sheet (11) / SiO _x layer (13) / cured resin layer (14) obtained above. The surface of the laminated film having the adhesive resin layer having a thickness of 20 μm formed on the release surface of the release sheet in advance on the surface of the laminate film having the optical isotropic base sheet (11) side. Are transferred by overlapping. Here, the peelable sheet with the adhesive resin layer is
On a release surface of a 50 μm-thick polyester film subjected to a release treatment with silicone, a polyolefin polyol (Epol, hydroxyl group content, manufactured by Idemitsu Petrochemical Co., Ltd.)
0.90meq / g, viscosity 75000cps / 30 ° C) 100 parts, IP
A solution comprising 50 parts of a solvent (aliphatic hydrocarbon solvent manufactured by Mitsui Petrochemical Industries, Ltd.) and 3 parts of a hydrogenated MDI (diphenylmethane diisocyanate) curing agent was cast,
It was formed by drying at 80 ° C. for 5 minutes. Protective film (1) having the above layer structure (adhesive resin layer (12) / optically isotropic base sheet (11) / SiO _x layer (13) / cured resin cured layer (14)) Has a total retardation value of 6 nm, a visible light transmittance of 86%, and a thickness of 55%.
The protective film (1) is adhered to at least one surface of the optical member (2) indicated by a dashed line as shown in FIG. The optical member (2) includes a polarizing plate, a retardation plate, a liquid crystal display panel already assembled (the outermost layer is a polarizing plate), and the like. As the polarizing plate, for example, a polarizing plate made of a polyvinyl alcohol / iodine system or the like and having a protective plate made of a cellulose triacetate film laminated on both sides using a pressure-sensitive adhesive is used. As the retardation plate, for example, one obtained by laminating a protective plate made of a cellulose triacetate film on both sides of a retardation film made of a uniaxially stretched polyvinyl alcohol film using a pressure-sensitive adhesive is used. As the liquid crystal display panel, for example, a panel having a configuration of a polarizing plate / a retardation plate / a liquid crystal cell / a polarizing plate using such a polarizing plate or a retardation plate is used. The above protective film (1) is not only flexible and flexible but also has good mechanical properties. The outermost layer after the protective film (1) is attached to the optical member (2) is a curable resin cured material layer (14), and the lower layer is SiO _x
Since it is formed of the layer (13), it has extremely excellent damage resistance, surface hardness, dust resistance, water resistance, moisture permeability, etc., and additionally has optical isotropy, so that display capability, hue, contrast Evaluation of optical performance such as this protective film (1)
Can be performed without peeling. Since the protective film (1) has a large adhesive force to the optical member (2), when the liquid crystal display panel is actually used, it can be permanently adhered as it is. However, it may be separated and removed. Example 2 A protective film (1) was obtained in the same manner as in Example 1 except that the conditions were as follows (the SiO _x layer (13) was the same as in Example 1). The obtained protective film (1) had the same excellent properties as in Example 1. <Photo-isotropic base sheet (11)> A film having a thickness of 20 μm, a retardation value of 5 nm, and a visible light transmittance of 92% was formed by casting from a 20% by weight solution using methylene chloride as a solvent. Polyarylate film. <Curable resin layer (14)> Phenoxy ether resin (manufactured by Toto Kasei Co., Ltd.) 40
A curable resin composition having a composition of 40 parts, 40 parts of methyl ethyl ketone, 20 parts of cellosolve acetate, and 40 parts of a 75% solution of an adduct of tolylene diisocyanate and trimethylolpropane (Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.). And dried at 80 ° C. for 4 minutes, and then heated at 130 ° C. for 20 minutes.
0 μm layer. <Adhesive Resin Layer (12)> 30 parts of an acrylic copolymer having a copolymerization ratio of butyl acrylate / 2-ethylhexyl acrylate / acrylic acid of 50/47/3 by weight, tolylene diisocyanate
A solution consisting of 1 part of a trimethylolpropane adduct and 70 parts of ethyl acetate was cast on the surface of the peelable sheet,
Thickness 20 formed by drying at ~ 90 ° C for 3 minutes
μm layer. [0054] The surface protective film of an optical member of the present invention exhibits, that, damage resistance and surface hardness is very good,
It has excellent properties such as solvent resistance, dust resistance, heat resistance, water resistance, moisture resistance, moisture resistance, air resistance, etc. ・ It is flexible and flexible. ・ It has optical isotropy, so its display ability hue, evaluation of the optical performance such as contrast can be performed without peeling the protective film (1), protective release operation and re-sticking operation of the film can be omitted at all, · SiO _x layer (13 ), The curable resin cured material layer (14) is provided on the substrate, so that the curable resin cured material layer (14) may be a material that may affect the optically isotropic base sheet (11) or the optically isotropic base. It is also possible to use a material having insufficient adhesiveness to the sheet (11), and to select a material having the optimum film properties.- Despite including the SiO _x layer (13), cracking during handling, etc. it is not likely to cause trouble, the installation of · SiO _x layer (13) is a low cost Since the kill, exhibits that you do not become a burden in terms of cost, excellent effects such as.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of the surface protective film of the present invention. DESCRIPTION OF REFERENCE NUMERALS (1) ... protective film, (11) ... optical isotropy base sheet (12) ... attaching resin layer, (13) ... SiO _x layer, (14) ... curable resin cured Layer, (2)… optical member

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tetsunosuke Kobayashi 1-4-16 Nihonbashi Bakurocho, Chuo-ku, Tokyo Inside Fujimori Kogyo Co., Ltd. (56) References JP-A-4-32805 (JP, A) Hei 2-148603 (JP, A) JP-A-60-159706 (JP, A) JP-A-60-159705 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 5 / 18 G02B 5/30-5/32 G02F 1/13 G02F 1/1335 G02F 1/137-1/141

Claims (1)

(57) [Claim 1] At least one of a polarizing element film and a retardation element film
A polarizing plate or a retardation plate having a configuration in which a protective plate is laminated on the surface, or a polarizing plate or a retardation plate with the protective plate
A liquid crystal display panel having a configuration in which the plates are stacked on the surface side ,
In the optical member (2) selected from , the optical member (2)
A protective film (1) for protecting the surface of the optical member (2) by sticking the protective plate on at least one surface of the optical member (2), wherein the protective film (1) is a single layer or An adhesive resin layer (12) is provided on one side of the multi-layered optically isotropic base sheet (11), and SiO _x (where 1 <
x <2) A surface protective film for an optical member, having a layer structure in which a cured resin layer (14) is provided via a layer (13).