JP2000266933A - Optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate and remove an unnecessary surface protection film from an optical member by forming at least one side outermost surface into a specific low oxygen layer. SOLUTION: At least one side outermost surface of an optical member 2 is formed out of a low oxygen layer 21 containing under 35% oxygen atom and over 60% carbon atom on the element ratio. In this case, the low oxygen layer 21 intends to restrain rise of adhesion force with the lapse of time of a surface protection film 1, and formed out of a substance containing under 35% oxygen atom and over 60% carbon atom on the element ratio. This low oxygen layer 21 is enough to be on the outermost surface of the side covered by the surface protection film 1. Namely the low oxygen layer 21 can be formed as an optical layer such as a polarizing plate or a phase difference plate forming the outermost surface of the optical member 2, or can be formed as an addition layer by a suitable system such as a coat system or a transfer system on the outermost surface of the optical member 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical member having excellent surface protective film releasability.

[0002]

BACKGROUND OF THE INVENTION Optical members used for forming a liquid crystal display (LCD) and the like, such as a polarizing plate, a retardation plate, and an elliptically polarizing plate obtained by laminating them, are punched into a predetermined size, stacked, transported, stored, and inspected. In order to prevent the surface of the optical member from being damaged at the time of handling such as a bonding process or the like, a surface protective film for covering one or both surfaces thereof is provided. The surface protective film is usually formed of a protective substrate provided with an adhesive layer, and is removed from the optical member when surface protection becomes unnecessary.

However, in the prior art, the adhesive strength of the surface protective film to the optical member increases with time, and the surface protection becomes unnecessary. In addition, there is a problem that the optical member is damaged due to an excessive increase in the adhesive force, which requires a lot of time and labor for stripping and removing, resulting in poor work efficiency. With the increase in LCD size, the trend has become more pronounced.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to the development of an optical member that can be easily peeled off and removed from an optical member when the surface protection film is not required because the adhesive force of the conventional surface protective film hardly increases with time. As an issue.

[0005]

According to the present invention, there is provided an optical device wherein at least one outermost surface comprises a low oxygen layer in which oxygen atoms are 35% or less and carbon atoms are 60% or more based on the element ratio. A member is provided.

[0006]

According to the present invention, the adhesion of the surface protective film adhered via the low oxygen layer is unlikely to increase with time, and the conventional surface protective film is adhered and required for punching, stacking transportation and storage. After taking measures such as inspection and bonding,
The unnecessary surface protection film can be easily peeled and removed from the optical member, the peeling and removing operation can be performed efficiently, and damage to the optical member at the time of peeling can be avoided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the optical member according to the present invention, at least one outermost surface has 35 oxygen atoms based on the element ratio.
% Or less and 60% or more of carbon atoms. An example is shown in FIG. 1 is a surface protective film, 2 is an optical member, 21 is its low oxygen layer, 3 is an adhesive layer, and 4 is a separator.

The optical member may be any suitable one used for forming a liquid crystal display device such as a polarizing plate, a retardation plate, or an elliptically polarizing plate obtained by laminating them, and the type thereof is not particularly limited. Therefore, the polarizing plate may be a reflection type or the like. Also, the retardation plate may have an appropriate purpose, such as a half-wave plate or a quarter-wave plate or viewing angle compensation. In the case of a laminated optical member such as the above-mentioned elliptically polarizing plate, the lamination may be performed through an appropriate bonding means such as an adhesive layer.

Incidentally, specific examples of the above-mentioned polarizing plate include iodine and / or iodine on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. Examples thereof include a film obtained by adsorbing a dichroic dye and stretching, a polarizing film made of a polyene oriented film such as a dehydrated product of polyvinyl alcohol and a dehydrochlorinated product of polyvinyl chloride. The polarizing plate may have a transparent protective layer on one or both sides.

On the other hand, the reflection type polarizing plate is provided with a reflection layer on the polarizing plate, and is used for forming a liquid crystal display device or the like of a type that reflects incident light from the viewing side (display side) to display. In addition, there is an advantage that a built-in light source such as a backlight can be omitted, and the thickness of the liquid crystal display device can be easily reduced. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is provided on one surface of the polarizing plate via a transparent protective layer or the like as necessary.

Specific examples of the reflective polarizing plate include a transparent protective layer which is matted if necessary, and a reflective layer formed by attaching a foil or a vapor-deposited film made of a reflective metal such as aluminum to one surface of the transparent protective layer. can give. Further, there may be mentioned, for example, those in which fine particles are contained in the transparent protective layer to form a fine surface uneven structure, and a reflective layer having a fine uneven structure is provided thereon. The reflective layer is used in a state where the reflective surface is covered with a transparent protective layer, a polarizing plate, or the like, in order to prevent a decrease in reflectance due to oxidation, and to maintain the initial reflectance for a long period of time, and to separately provide a protective layer. Is more preferable.

The reflective layer having the above-described fine uneven structure has an advantage that the incident light is diffused by irregular reflection to prevent directivity and glaring appearance, and that unevenness in brightness can be suppressed.
Further, the transparent protective layer containing fine particles also has an advantage that the incident light and the reflected light thereof are diffused when transmitting the light and the unevenness of light and darkness can be further suppressed.

The reflection layer having a fine uneven structure reflecting the fine uneven structure on the surface of the transparent protective layer is formed by an appropriate method such as an evaporation method such as a vacuum evaporation method, an ion plating method and a sputtering method, and a plating method. The method can be performed by directly attaching a metal to the surface of the transparent protective layer.

For the formation of the transparent protective layer in the above-mentioned polarizing plate, a polymer or the like having excellent transparency, mechanical strength, heat stability and moisture shielding properties is preferably used. Examples of such resins include polyester resins and acetate resins, polyethersulfone resins and polycarbonate resins,
Examples of the resin include a polyamide resin, a polyimide resin, a polyolefin resin, an acrylic resin, and a thermosetting resin such as an acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin, or an ultraviolet curable resin.

The transparent protective layer may be formed by an appropriate method such as a method of applying a polymer or a method of laminating a film, and the thickness may be appropriately determined. Generally 500 μm
Hereinafter, the thickness is preferably 1 to 300 μm, particularly 5 to 200 μm. The fine particles to be contained in the formation of the transparent protective layer having the fine surface irregularity structure include, for example, an average particle size of 0.5 to 5
Transparent inorganic fine particles of 0 μm silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like, and organic fine particles of a crosslinked or uncrosslinked polymer, etc. Fine particles are used. The amount of fine particles used is 1
It is common to use 2 to 50 parts by weight, especially 5 to 25 parts by weight, per 100 parts by weight.

On the other hand, as a specific example of the above retardation plate, a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefin, polyarylate, or polyamide is stretched. Birefringent film or liquid crystal polymer oriented film,
Examples thereof include a film in which an alignment layer of a liquid crystal polymer is supported by a film.

The retardation plate may have an appropriate retardation in accordance with the intended use, for example, various wavelength plates or those for the purpose of compensating the viewing angle or the like by coloring the birefringence of the liquid crystal layer. A structure in which optical characteristics such as retardation are controlled by laminating more than two kinds of retardation plates may be used.

The optical member may be formed by laminating two or three or more optical layers, such as a laminate of the above-mentioned elliptically polarizing plate, reflection type polarizing plate and retardation plate. Therefore, a combination of a reflective polarizing plate and a retardation plate or a combination of a polarizing plate and a compensating retardation plate may be used.

The optical member in which two or three or more optical layers are laminated can be formed by a method in which the optical members are sequentially laminated separately in a manufacturing process of a liquid crystal display device or the like. The method described above has an advantage in that it is excellent in quality stability, assembling workability, and the like, and can improve manufacturing efficiency of a liquid crystal display device and the like.

The low oxygen layer, which forms the outermost surface of the optical member on the side covered with the surface protective film with the adhesive cover, has the purpose of suppressing an increase in the adhesive force of the surface protective film over time. Is formed of a substance having 35% or less and 60% or more of carbon atoms.

The above-mentioned substance in which the oxygen atom exceeds 35% and the carbon atom is less than 60% has a poor effect of suppressing the increase in the adhesive force with time. The low oxygen layer, which is preferable from the viewpoint of suppressing the increase of the adhesive force with time, is composed of a substance containing 33% or less, particularly 30% or less of oxygen atoms, 63% or more, and especially 65% or more of carbon atoms. .

Therefore, the oxygen content of the low oxygen layer is 3%.
It can be formed of an appropriate substance having a molecular composition of 5% by weight or less and a carbon atom content of 60% by weight or more. The low oxygen layer may be on the outermost surface of the optical member on the side covered with the surface protective film as described above.

Therefore, the low oxygen layer may be formed as an optical layer such as the above-mentioned polarizing plate or retardation plate which forms the outermost surface of the optical member, or may be formed on the outermost surface of the optical member by a coating method, a transfer method or the like. May be formed as an additional layer by an appropriate method. In the case of the addition method, a substance having excellent transparency that satisfies the above element ratio can be preferably used from the viewpoint of maintaining the optical characteristics of the optical member.

In the case of the low-oxygen layer formed by the above-mentioned addition method, the thickness is thinner, for example, 5 μm or less, in order to prevent a decrease in light transmittance or an increase in haze and maintain a high optical characteristic of the optical member. It is particularly preferable to form a low oxygen layer having a thickness of 1 μm or less. The low oxygen layer by the addition method may be removed from the optical member together with the surface protective film when the surface protective film is peeled off, or may remain on the optical member.

In general, the surface of an optical member such as an ethylene-vinyl acetate copolymer is strongly applied to prevent the influence on the optical characteristics of the optical member due to the variation in the remaining state of the low oxygen layer due to removal or non-removal. It is preferable that the low-oxygen layer is an addition type low-oxygen layer which adheres to the surface protection film and remains well without being removed from the optical member when the surface protection film is peeled off.

Therefore, in the case where such a residue is intended, a material such as a release coat applied to the separator which is easily peeled from the supporting substrate and transferred to the adhesive layer side is not preferable even if the above element ratio is satisfied. . In addition, as described above, the low oxygen layer
Since the outermost surface of the optical member on the side covered with the surface protection film is formed, the optical member can be formed as the outermost surface on one side or both sides of the optical member.

As described above, the optical member according to the present invention has a form in which the low oxygen layer 21 of the optical member 2 is adhered and covered with the surface protection film 1 as shown in the drawing, or is further exposed to the other surface of the optical member. The surface is provided for processing, transportation, and the like as a form in which the adhesive layer 3 whose surface is temporarily covered with the separator 4 is provided.

As the above-mentioned surface protective film, there is usually used a film in which an adhesive layer is provided on a protective substrate as described above so that the protective substrate can be peeled off from the optical member together with the adhesive layer. In FIG. 1, 11 is a protective substrate, and 12 is an adhesive layer. On the other hand, the adhesive layer provided on the optical member together with the separator is for bonding to another member such as a liquid crystal cell, and is provided so that the adhesive layer remains on the optical member side when the separator is peeled off.

For forming the adhesive layer of the surface protective film and the adhesive layer for bonding other members, for example, acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based, rubber-based, etc. An adhesive substance or an adhesive having an appropriate polymer as a base polymer can be used, and there is no particular limitation. Above all, for the formation of the adhesive layer for bonding other components, it has excellent optical transparency like acrylic adhesive, shows appropriate wettability, cohesiveness and adhesive adhesive properties, weather resistance and heat resistance Those having excellent properties can be preferably used.

In addition to the above, the pressure-sensitive adhesive layer for bonding other members can prevent a foaming phenomenon and a peeling phenomenon due to moisture absorption, prevent a decrease in optical characteristics due to a difference in thermal expansion, prevent a liquid crystal cell from warping, and provide high quality and durability. From the viewpoint of excellent formability of a liquid crystal display device, it is preferable that the liquid crystal display device is formed of a material having a low moisture absorption rate and excellent heat resistance.

The adhesive layer is made of, for example, natural or synthetic resins, especially, tackifier resins, glass fibers and glass beads, fillers and pigments made of metal powders and other inorganic powders, coloring agents and oxidizing agents. It may contain an appropriate additive such as an inhibitor which may be added to the adhesive layer. Further, the pressure-sensitive adhesive layer for bonding other members may be one containing fine particles and exhibiting light diffusivity.

The attachment of the adhesive layer to the protective substrate or the optical member can be performed by an appropriate method. By the way, as an example,
For example, an adhesive substance or a composition thereof is dissolved or dispersed in a solvent composed of an appropriate solvent alone or a mixture of appropriate solvents such as toluene and ethyl acetate to prepare an adhesive liquid of about 10 to 40% by weight, and it is cast. A method of directly attaching on a protective substrate or an optical member by an appropriate development method such as a method or a coating method, or forming an adhesive layer on a separator according to the above and forming it on a protective substrate or an optical member. Transfer method and the like.

The pressure-sensitive adhesive layer may be provided on the protective substrate or the optical member as a superposed layer of different compositions or types. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, and the like, and is generally 1 to 500 μm, preferably 5 to 20 μm.
0 μm, especially 10 to 100 μm. The pressure-sensitive adhesive layer provided on the protective substrate or the optical member may have the same composition or type, or may have a different composition.

The protective substrate for forming the surface protective film may be a suitable thin leaf according to the prior art, for example, a plastic film or rubber sheet, paper or cloth, nonwoven fabric or net, foamed sheet or metal foil, or a laminate thereof. The body can be used. The thickness of the protective substrate can be appropriately determined according to the strength and the like, and is generally 500 μm or less, particularly 5 to 300 μm,
In particular, it is 10 to 200 μm.

On the other hand, the purpose of the separator for temporarily covering the exposed surface of the adhesive layer is to prevent contamination of the adhesive layer until the adhesive layer is put to practical use. The separator is formed by, for example, providing a suitable thin film according to the above-mentioned protective base material with a coating of a suitable release agent such as a silicone-based or long-chain alkyl-based, fluorine-based or molybdenum sulfide, if necessary. Can be.

In the present invention, each layer such as a polarizing plate, a retardation plate, a transparent protective layer and an adhesive layer forming the above-mentioned optical member is formed of, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound or a cyano compound. A material having an ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorbent such as an acrylate compound or a nickel complex salt compound may be used.

The optical member according to the present invention can be preferably used for forming various devices such as a liquid crystal display device.

[0038]

EXAMPLE 1 A transparent protective layer made of a triacetyl cellulose film was adhered to both sides of a polyvinyl alcohol-based polarizing film via a polyvinyl alcohol-based adhesive layer to a thickness of 180 μm.
One side of an ethylene-vinyl acetate copolymer
A low-oxygen layer having a thickness of 1 μm or less is provided by applying a weight-% ethyl acetate solution and drying, and a 50 μm-thick PET is formed thereon.
An optical member was obtained by adhering a surface protection film having a 20 μm-thick acrylic adhesive layer to the film by reciprocating a 2 kg rubber roller once.

Comparative Example An optical member was obtained in the same manner as in Example 1 except that a surface protective film was directly adhered on a triacetyl cellulose film (transparent protective layer) without providing a low oxygen layer.

Evaluation Test The adhesive strength of the surface protective film on the optical member obtained in Example 1 and Comparative Example was measured immediately after adhesion (initial stage) and at 150 ° C.
After heating for a period of time (elapsed time), it was examined. The adhesive strength is 1
Based on 80 degree peel (peeling speed 300 mm / min).

The results are shown in the following table. The table also shows the elemental ratios of oxygen atoms and carbon atoms of the surface of the layer made of the ethylene / vinyl acetate copolymer or the surface of the layer made of the triacetyl cellulose film, which were examined by elemental analysis using ESCA. Oxygen atom Carbon atom Initial adhesive strength Adhesive strength with time (%) (%) g / 50 mm g / 50 mm Example 1 27 69 30 45 Comparative Example 40 55 34 92

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of an optical member.

[Explanation of symbols]

 1: Surface protective film 11: Protective substrate 12: Adhesive layer 2: Optical member 21: Low oxygen layer 3: Adhesive layer 4: Separator

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuji Shiki 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Inside Nitto Denko Corporation (72) Inventor Tomomori Masada 1-1-1, Shimohozumi, Ibaraki City, Osaka Prefecture No.2 Nitto Denko Corporation F term (reference) 2H049 BA02 BA04 BA06 BA07 BB03 BB23 BB28 BB33 BB43 BB54 2K009 AA12 BB11 CC03 CC14 CC34 CC42 DD01 DD02

Claims (3)

[Claims] At least one outermost surface has an oxygen atom of 35% or less and a carbon atom of 60% based on the element ratio.
%, Which comprises a low oxygen layer having a concentration of not less than 10%. 2. The optical member according to claim 1, further comprising a surface protection film for adhesively covering the low oxygen layer, and an adhesive layer having an exposed surface temporarily covered with a separator on the other surface of the optical member. 3. The optical member according to claim 1, wherein the optical member has at least a polarizing plate or a retardation plate.