JPH11202104A - Lens film, surface light source and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the adhesion of foreign matter by peeling static electricity which occurs at the time of peeling a protective film and the unequal adhesion by the static electricity admitted at the time of laminating and using two lens films by including a conductive high polymer having a polythiophene skeleton into a conductive layer disposed on at least one surface of a base material film. SOLUTION: The lens film 10 is formed by laminating the transparent base material film 1, the conductive layer 2 disposed on at least one surface of this base material film 1 and a lens layer 3 consisting of a concave lens or convex lens on the conductive layer 2. The conductive layer 2 contains the conductive high polymer having the polythiophene skeleton. The surface resistance of the conductive layer 2 of the surface light source ms below 10<12> Ω/square. The lens film 10 prevents the generation of the static electricity up to the surface of the lens layer 3 by the effect of the conductive layer 2 disposed on the base material film 1. Then, an electrostatic charge quantity is less even right after the peeling of the protective film of the lens film 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens film excellent in dustproofness and a surface light source using the same, and more particularly to a lens film used in displays such as word processors, computers, televisions, and liquid crystal displays, the surface of which is contaminated with dust. The invention belongs to a surface light source and a liquid crystal display device which are excellent in prevention property and lamination property without adhesion unevenness when laminated.

[0002]

2. Description of the Related Art A lens film to be incorporated into a display of an electronic device such as a personal computer or a word processor as a component of various other commercial displays, etc., has one surface of a conductive layer base film embossed or provided on a transparent base film. A lens layer obtained by press-curing a thermoplastic resin, an ultraviolet curable resin, or the like was provided. These lens films have been used by being incorporated in a liquid crystal display device or the like.

Conventionally, when these lens films are assembled with a surface light source device, the protective film covering the lens film is peeled off and used. However, peeling static electricity generated at this time causes foreign matter to adhere to the surface light source device. There was a problem that caused. In many cases, the prism-shaped ridges of two lens films are used so as to be orthogonal to each other. At this time, the prism surface of the lower lens film and the flat surface of the base material of the upper lens film partially adhere to each other due to the influence of static electricity. There was a problem that caused the failure.

In order to prevent the generation of static electricity, attempts have been made to provide a conductive layer by applying an antistatic agent to the surface of a lens having a concave or convex shape. However, the conductive layer is formed into a uniform film. It is technically difficult to provide the lens film, and the appearance of the lens film and the image of the liquid crystal display device become non-uniform, so that the optical characteristics are significantly impaired and the conductive layer is dropped. In addition, although a technique for forming a conductive thin film layer by metal vapor deposition is also disclosed, it is difficult to uniformly provide vapor deposition on a lens having a concave-convex shape, which leads to variations in optical characteristics and high cost. There was a problem.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a lens film used for a liquid crystal display device or the like, in the process of assembling with a surface light source device, adhesion of foreign matter due to peeling static electricity generated when a protective film is peeled off, or two sheets. It is an object of the present invention to provide a lens film having a conductive layer that solves problems caused by static electricity such as uneven contact when a prism-shaped ridge line of a lens film is used orthogonally.

[0006]

According to the present invention, there is provided a transparent base film, a conductive layer provided on at least one surface of the base film, and a concave lens formed on the conductive layer. Alternatively, the conductive film is a lens film including a conductive polymer having a polythiophene skeleton. The conductive layer is a lens film having a resistivity of 10 ¹² Ω / □ or less. The invention according to claim 3 is the lens film 10 described above.
Is a surface light source configured by arranging the light receiving surface 6 on the light emission side of a light source formed in a planar shape with a reflective film. According to a fourth aspect of the present invention, there is provided a liquid crystal display device including the surface light source provided on a substrate in which a liquid crystal layer is sealed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lens film 10 of the present invention comprises:
A transparent base film 1 shown in FIG. 1, a conductive layer 2 provided on at least one surface of the base film, and a lens layer 3 formed of a concave lens or a convex lens on the conductive layer.
And the conductive layer 2 is a lens film containing a conductive polymer having a polythiophene skeleton. The surface light source has a surface resistance of the conductive layer 2 of 10 ¹² Ω / □ or less. Further, according to the invention of claim 3, the light receiving surface 6 of the lens film 10 is provided on a diffusion film 25 which is formed by stacking the light source 21 as shown in FIG. The surface light source 20 is arranged. And the invention of claim 4 is that the surface light source 20 is
Liquid crystal display device 3 provided on substrate 32 enclosing liquid crystal layer 30
5 Therefore, the transparent base film 1 shown in FIG.
A lens film 1 provided with a lens layer 2 via a primer layer 2P to firmly stabilize the adhesion as required.
1, although not shown, has a different configuration from a conventional lens film in which an antistatic layer is provided on the lens layer.

[0008] The transparent base film constituting the lens film of the present invention includes cellulose triacetate, polyester, polyamide, polyimide, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, polymethyl methacrylate, polycarbonate, polyurethane and the like. A stretched or unstretched film of a thermoplastic resin can be used. Although the thickness depends on the rigidity of the film, it is preferably 50 to 200 μm from the viewpoint of handling such as workability. The layer on which the conductive layer is provided is preferably subjected to an easy-adhesion treatment such as a corona discharge treatment in order to firmly stabilize the adhesion with another layer to be laminated.

The conductive layer provided on the transparent substrate film is preferably formed by polymerizing polydialkoxythiophene represented by the chemical formula 1 in the presence of a polyanion.

[0010]

Embedded image

Wherein R ₁ and R ₂ are H or C ₁ -C ₄
Represents an alkyl group of
_A C ₁ -C ₄ alkylene group, preferably a methylene group which can be optionally substituted, an ethylene group, a propylene group, or a 1,2, which may be substituted with a C ₁ -C ₁₂ alkyl or phenyl group;
-A dispersion of polythiophene representing cyclohexylene groups. Representative examples of the C ₁ -C ₁₂ alkylene which R ₁ and R ₂ can form simultaneously or are formed include α-olefins such as ethene, propene, 1-hexene, 1-octene, 1-decene , 1-dodecene and 1,2-alkadienes derived from 1,2-dibromoalkane, and other 1,2-cyclohexadienes,
Preferred R ₁ and R ₂ such as 3-butadiene and 2,3- {methyl-2,3-butylene and 2,3-pentadiene are methylene, ethylene, α-propylene,
Particularly, ethylene can be preferably used.

The polyanion is a polymeric carboxylic acid, such as polyacrylic acid, polymethacrylic acid, or polymaleic acid, or a polymeric sulfonic acid, such as polystyrene sulfonic acid or polyvinyl sulfonic acid. The polymer carboxylic acid or polymer sulfonic acid can be a copolymer of vinyl carboxylic acid or vinyl sulfonic acid with another polymerizable monomer such as acrylate, methacrylate, or styrene. The molecular weight of the polymeric acid that provides the anion ranges from 1000 to 200,000, preferably from 2000 to 50,000. And it is marketed as a high molecular acid or its alkali salt.

As the polyanion to be present when polymerizing the polydialkoxythiophene used in the present invention, a mixture of a free carboxylic acid and / or an alkali salt of the corresponding acid can be used.

The conductive layer made of a conductive polymer having a polythiophene skeleton as a skeleton is provided on a transparent base film by coating. The conductive layer is colorless and transparent, and has a surface resistance of 10 ¹² Ω /. □, which has the property that its conductivity does not decrease over time.

The formation of the conductive layer by coating depends on the condition of the base film, the post-processing method, the viscosity of the coating liquid and the drying property (evaporation rate) of the solvent, but usually, the base in the wound state is used. Applied to the material film. The coating method can be a roll coating, a gravure coat, a bar coat, an air knife coat, an extrusion coat, or the like, and can be formed by a conventionally known method according to the properties of the paint and the amount of coating. Further, the conductive layer is preferably formed directly on the base film or via a primer layer for strengthening the adhesion. Then, the adhesion between the lens layer and the base film can be strengthened by imparting the function of the primer layer to the conductive layer.

The conductive layer of the present invention can be provided not only on one side of the base sheet 1 but also on both sides of the base sheet as shown in FIG. 2 or FIG. As shown in FIG. 2, the conductive layer 2 provided on the other side of the lens layer 10 can have higher conductivity than that provided on one side.
Further, as shown in FIG. 3, a lens layer having characteristics such as light condensing and diffusion may be provided on the lens layer 3 on the light receiving surface 6 side on the conductive layer 2 provided on the other side, as shown in FIG.

The resin composition (dispersion medium) of the coating liquid in which the conductive polymer having a polythiophene skeleton is dispersed has good adhesion to the base film, and has light resistance and moisture resistance as a resin composition. And those having good adhesion to the lens layer provided on the conductive layer. For those mainly composed of thermoplastic resin, linear polyester, polyurethane, acrylic resin, polyvinyl butyral, polyamide, vinyl chloride / vinyl acetate copolymer, etc. Added binders can be used.

The binder of the reaction-curable resin composition includes polyester polyol / polyisocyanate, polyether polyol / polyisocyanate, polyacrylpolyl polyol / polyisocyanate, epoxy / polyisocyanate, and ionizing radiation-curable resin. Can also be used. As the polyisocyanate, aromatic and / or aliphatic diisocyanates and triisocyanates are widely used.

The thickness of the conductive layer formed by coating is 0.1
To 5 μm (the coating amount in the present specification is described in terms of solid content; the same applies hereinafter). If the transparent conductive layer does not adhere firmly to the transparent substrate film depending on the type of the base film or binder, or if the adhesive strength decreases due to the aging effect of cold heat, moisture absorption and desorption, etc. It is preferable to form a conductive layer by providing a primer film having an adhesive action on both surfaces of a material film and a transparent conductive layer on a base film.

The lens layer according to the present invention is obtained by forming a thermoplastic resin having an appropriate hardness and moldability or a reaction-curable resin in a liquid state on a conductive base layer in a transparent base film. It is constituted by applying and shaping the surface of the conductive layer. Then, as shown in FIGS. 1 to 3, it is preferable that the concave portion of the lens layer is provided so that the coating film having the concave portion thickness h of 0.5 to 3 μm covers the entire surface.

The resin composition constituting the lens layer of the present invention is a (meth) acrylate of a polyfunctional compound such as a polyhydric alcohol (hereinafter, acrylate and methacrylate are referred to as (meth) acrylate in the present specification). ) And relatively high amounts of reactive diluents. Examples of the diluent include monofunctional monomers such as ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, vinyltoluene, and N-vinylpyrrolidone, and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate and hexanediol. (Meth) acrylate,
Tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6 hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate and the like.

Further, when the above-mentioned ionizing radiation-curable resin is used as an ultraviolet-curable resin, acetophenones, benzophenones, Michler benzoyl benzoate, α-amyloxime ester, etc. Thioxanthones and n- as photosensitizers
Butylamine, triethylamine, tri-n-butylphosphine and the like are mixed and used.

The above ionizing radiation-curable resin may contain the following reactive organosilicon compound. R _m S
i (OR ′) _n , where R and R ′
Represents an alkyl group having 1 to 10 carbon atoms, m + n = 4, and m and n are each an integer. More specifically, tetramethoxysilane, tetraethoxysilane,
Tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-
sec-butoxysilane, tetra-tert-butoxysilane, tetrapentaethoxysilane, tetrapenta-
iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-t
ert-butoxysilane, methyltrimethoxysilane,
Methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, dimethylpropoxysilane, dimethylbutoxysilane, methyldimethoxysilane, methyldiethoxysilane, hexyl Trimethoxysilane and the like.

The lens layer 3 can be formed using not only the above-mentioned reaction-curable resin but also a thermoplastic resin. For example, methyl methacrylate, acrylic resin such as ethyl methacrylate, polyethylene terephthalate, pobutylene terephthalate, polyester such as polyethylene naphthalate, polycarbonate, polystyrene, polypropylene, polyhydrocarbon such as polymethylpentene, 6,6 nylon, Polyamide such as 6 nylon, saponified ethylene / vinyl acetate copolymer, polyimide, polysulfone, polyvinyl chloride,
It can be selected from thermoplastic resins such as acetyl cellulose.

The formation of a lens layer using a reaction-curable resin is carried out in the steps of coating, forming and curing shown in FIG. That is, an ionizing radiation-curable resin is sent to a die head 86 by a pump 87 to a plate cylinder 88 having a prism shape or the like, and the resin 82 is uniformly pressed into the plate cylinder. On the other hand, the surface of the conductive layer 2 provided on the surface of the transparent substrate film 1 and the entrance nip 83
To form a cured ionizing radiation-curable resin 81 and adhere to the conductive layer 2 by irradiating ionizing radiation with an ionizing radiation irradiating device 85. Then, the lens layer 3 formed on the transparent substrate film 1 from the plate cylinder 88 at the exit nip 84 is peeled from the plate cylinder 88 to form the lens film 10.

As the thermoplastic resin, a resin composition to which additives such as a heat stabilizer and a light stabilizer are appropriately added is used. That is, the conductive layer provided on the transparent base film is provided with a primer layer for strengthening adhesion as required, and is extruded and coated in a heated and melted state, and is formed into a lens shape by a cooling roll, or the heat is applied. A lens film can be formed by extruding a plastic resin layer, cooling and then reheating / melting and shaping.

The lens layer has a prism shape shown in FIG.
It is possible to arbitrarily form a concavo-convex shape such as (B) a pyramid shape, FIG. 6 (A) a semi-spherical shape, (B) an inverted semi-circular shape, or (C) a hemispherical shape.

FIG. 7 shows a liquid crystal display device 3 provided with an edge type surface light source 20 as an example using the lens film of the present invention.
5 is a sectional view of FIG. The light source 21 is disposed on the side surface of the light guide plate 22 provided with the light diffusion pattern 23 on the side facing the light receiving surface 6 of the lens film. Then, a liquid crystal layer 30 is attached to a lower substrate 32 and an upper substrate on the side of the light emitting surface 7 of the lens film 10 provided on the diffusion film 25 on a planar light source formed by providing the reflection film 24 so as to surround the light guide plate 22. The liquid crystal display device 35 is constituted by providing a liquid crystal panel sealed between the liquid crystal display device 31 and the liquid crystal display device 31. 7 illustrates an example in which one lens film is used. However, two lens films are used and stacked so that their ridges are orthogonal to each other. The directions of the ridges may be orthogonal, parallel, or at any angle.

[0029]

Hereinafter, the present invention will be described in more detail with reference to examples. (Example 1) As shown in FIG. 1, a conductive coating agent Baytron (having a composition (1) shown below) was applied on one surface of a polyester film A-4300 (base film 1, manufactured by Toyobo Co., Ltd.) having a thickness of 125 μm. (Trade name, manufactured by Bayer K.K.) was dispersed in the following emulsion (dispersion medium) to prepare a coating liquid A. Then, the above-mentioned coating solution A is applied by an air knife method, dried at 100 ° C. for 1 minute, and has a thickness of 0.1
A μm conductive layer 2 was formed. Next, epoxy acrylate Z9002A (reaction-curable resin manufactured by Nippon Synthetic Rubber Co., Ltd.) is filled and adhered to the prism plate on the conductive layer 2, irradiated with ultraviolet rays and cured to form a prism shape (vertical angle 97).
The lens film 10 of Example 1 having a degree of pitch of 50 μm and a thickness h of the concave portion of 1 μm was prepared. After the formation of the lens film, a protective film was provided on the surface thereof and stored in a laminated state. (Composition of conductive coating agent) ・ 0.5 parts by weight of polyethylene dialkoxythiophene (PEDT) ・ 0.8 parts by weight of polystyrenesulfonic acid (PSS) ・ 98.7 parts by weight of water “Coating liquid A” ・ Conductive coating Agent 38.5 parts by weight ・ Finetex ES-850 (dispersion medium) 16.7 parts by weight (brand name of polyester emulsion DIC) ・ Solvent (water / isopropyl alcohol = 3/1) 44.8 parts by weight

(Example 2) The lens film of Example 2 was prepared in the same manner as in Example 1 except that the composition of the coating liquid used in Example 1 was as follows. 1
0 was created. "Coating liquid B"-77.0 parts by weight of conductive coating agent-16.7 parts by weight of Finetex ES-850 (dispersion medium)-6.3 parts by weight of solvent (water / isopropyl alcohol = 3/1)

Example 3 The lens film of Example 3 was prepared in the same manner as in Example 1, except that the composition of the coating liquid used in Example 1 was as follows. 1
0 was created. "Coating liquid C"-Conductive coating agent 9.5 parts by weight-Finetex ES-850 (dispersion medium) 16.7 parts by weight-Solvent (water / isopropyl alcohol = 3/1) 73.8 parts by weight

Example 4 The lens film of Example 3 was prepared in the same manner as in Example 1 except that the composition of the coating liquid used in Example 1 was as follows. 1
0 was created. "Coating liquid D"-2.4 parts by weight of conductive coating agent-16.7 parts by weight of Finetex ES-850 (dispersion medium)-80.9 parts by weight of solvent (water / isopropyl alcohol = 3/1)

(Comparative Example 1) Comparative Example 1 having a lens layer 2 of the same shape, except that the conductive layer was not used in the same steps as in Example 1 except that the conductive layer coat used in Example 1 was omitted.
Was prepared.

Table 1 shows the results of evaluating the following items for each sample prepared in the examples and comparative examples. Surface resistance The surface on which the conductive layers are laminated is measured with a resistivity meter (MCP-HT26).
0: trade name, manufactured by Mitsubishi Chemical Corporation). Luminance on backlight As shown in FIG. 7, a diffusion film 25 is placed on the light guide plate 22 of the edge type backlight, and any one of the lens films of the example and the comparative example is further laminated to obtain luminance in the normal direction.
It measured using BM-7 (luminance meter Topcon) and evaluated the inferiority with the comparative example. Adhesion unevenness As shown in FIG. 7, a diffusion film 25 is placed on the light guide plate 22 of the edge type backlight, and any of the lens films of the examples or the comparative examples is further laminated, and immediately after the protective film is peeled off, The lens film was overlapped so that two ridge lines were orthogonal to each other, and the adhesion unevenness of the lens film was visually confirmed on the backlight. Comprehensive evaluation When the surface resistance is 10 × 10 ¹² Ω / □ and the lens film is placed on the backlight,
Comprehensively evaluate the presence / absence of adhesion unevenness, decrease in brightness,
◎, △, Δ to × (excellent to unacceptable) were evaluated.

[0035]

[Table 1]

[0036]

The lens film of the present invention has the effect of preventing the generation of static electricity up to the surface of the lens layer by the action of the conductive layer provided on the base film. Therefore, the charge amount is small even immediately after the protective film of the lens film is peeled off. Therefore, when assembling with the surface light source device, it is seen when foreign matter adheres due to peeling static electricity generated when the protective film is peeled from the lens film, or when the prism-shaped ridge lines of the two lens films are used orthogonally. This has the effect of eliminating problems caused by static electricity such as uneven contact.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a basic configuration of a lens film of the present invention.

FIG. 2 is a schematic sectional view showing a configuration of another lens film of the present invention.

FIG. 3 is a schematic sectional view showing a configuration of another lens film of the present invention.

FIG. 4 is a schematic sectional view showing an example of a conventional lens film.

FIG. 5 is a perspective view showing an example of a concave-convex lens.

FIG. 6 is a perspective view showing another example of a concave-convex lens.

FIG. 7 is a cross-sectional view showing a state where the lens film of the present invention is incorporated in a liquid crystal display together with a surface light source.

FIG. 8 is a schematic cross-sectional view illustrating a step of forming a lens layer according to the present invention.

DESCRIPTION OF SYMBOLS 1 Base film 2 Conductive layer 2P Primer layer 3 Lens layer 6 Light receiving surface 7 Light emitting surface 10 Lens film 11 Lens film of comparative example 20 Edge type surface light source 21 Light source 22 Light guide plate 23 Diffusion pattern 24 Reflection Film 25 Diffusion film 30 Liquid crystal layer 31 Upper substrate 32 Lower substrate 35 Liquid crystal display device 81 Cured resin 82 Pressed resin 83 Inlet nip 84 Outlet nip 85 Ionizing radiation irradiation device 86 Die head 87 Pump 88 Plate cylinder h Thickness of lens layer concave portion

Claims (4)

[Claims] 1. A method comprising: laminating a transparent base film, a conductive layer provided on at least one surface of the base film, and a lens layer comprising a concave lens or a convex lens on the conductive layer; A lens film, wherein the layer contains a polythiophene skeleton. 2. The lens film according to claim 1, wherein the surface resistance of the conductive layer is 10 ¹² Ω / □ or less. 3. A surface light source, wherein the light receiving surface of the lens film according to claim 1 is arranged on a light emitting side of a planar light source formed of a reflective film. 4. A liquid crystal display device comprising the surface light source according to claim 3 on a substrate in which a liquid crystal layer is sealed.