JP2007093726A - Black sheet for back light type liquid crystal panel display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a black sheet for a back light type liquid crystal panel display thin while suppressing a decrease in light absorbing performance. <P>SOLUTION: Disclosed is the black sheet for the back light type liquid crystal panel display which has a stacked structure, wherein a surface layer is formed of black silicone rubber and made to abut on a liquid crystal module surface of the back light type liquid crystal panel display so that light of a back light is absorbed on the abutting surface layer, the black sheet for the back light type liquid crystal panel display being characterized in that the surface layer is formed by using liquid silicone rubber and at least one black layer which is colored in black is provided on the back side of the surface layer separately from the surface layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a black sheet for a backlight type liquid crystal panel display.

In recent years, liquid crystal display panels have been widely used as display elements.
In the liquid crystal module of this liquid crystal display panel, as shown in FIG. 1, a laminate of a plurality of glass plates such as an electrode plate 12 sandwiching the liquid crystal 11 and a functional resin film material such as an alignment film 15 and a polarizing plate 16. In general, the center of the surface is formed as a liquid crystal display region, and the laminate is sandwiched from the front side and the back side by a frame material 13 made of metal or the like outside the peripheral liquid crystal display region. It is integrated.
At this time, in order to prevent the glass plate 12 used for the liquid crystal module 1 from being broken by an impact, between the frame material 13 on one of the front side and the back side and the laminate, A sheet 14 using silicone rubber is disposed (Patent Document 1).

  By the way, a liquid crystal panel display using such a liquid crystal module includes a so-called reflective type in which external light is reflected by a reflector on the back side of the liquid crystal module and a light source is provided on the back side of the liquid crystal module. There is known a so-called backlight type in which a liquid crystal display unit transmits light from this light source and performs display. This backlight type liquid crystal panel display is widely used because it is bright and easy to see. For the backlight 2 of the backlight type liquid crystal panel display, for example, a cold cathode tube 21 having substantially the same length as the width of the liquid crystal module 1, a light guide plate 22 having substantially the same area as the liquid crystal module 1, and a light diffusion plate 23 are used. The so-called side light type is known. The light guide plate 22 is formed so as to introduce light from the side end face and emit light from the entire surface. In the above-mentioned side light type liquid crystal panel display, the cold cathode tube 21 is provided on the back side of the liquid crystal module 1. The light emitted from the cold cathode tubes 21 is emitted from the light guide plate 22 over the entire back surface of the liquid crystal module 1. At this time, if the luminance is uneven in the liquid crystal display area, it becomes difficult to see the display on the liquid crystal panel display. Therefore, the light diffusing plate 23 is used between the light guide plate 22 and the liquid crystal module, and light emitted from the light guide plate 22 is emitted. To suppress unevenness in luminance.

  By the way, it is known that resin materials such as glass, rubber, and plastic have a refractive index greatly different from that of air, and light is refracted according to the difference in refractive index at the interface of these different refractive indexes. For example, the angle formed by the light beam obliquely transmitted through the glass / air interface with the interface is larger in the glass than in the air. For this reason, the light beam that has traveled through the glass toward the glass / air interface cannot be transmitted to the air side and is totally reflected at an angle shallower than a certain degree. In the liquid crystal module of the backlight type liquid crystal panel display, it is known that the diffused light from the light diffusing plate is likely to be incident at a shallow angle, particularly in the peripheral part, and stray light called flare occurs, and this flare occurs. In the liquid crystal display area, there is a risk of unevenness in luminance. Therefore, in Patent Document 2, a black member such as a black tape is brought into contact with the outside of the liquid crystal display area (periphery) of the liquid crystal module to absorb light It is described. That is, by suppressing the formation of a glass / air interface or a resin / air interface having a significantly different refractive index by bringing a resin material into contact with a glass material or a resin material on the front or back surface of the liquid crystal module, The reflection of light at the interface is suppressed. And since it is colored black, light is easily absorbed and reflection of light is further suppressed, and the occurrence of flare is suppressed.

  The black sheet used in contact with the front and back surfaces of the liquid crystal module must have excellent heat resistance to withstand the heat generated by the backlight and excellent cushioning to prevent the glass material from cracking. For this reason, black silicone rubber is usually used for the surface layer. In addition, this silicone rubber surface layer is conventionally calendered using a millable type silicone rubber or coated with a liquid silicone rubber to form a polyethylene terephthalate (hereinafter also referred to as “PET”) film or the like. On the base material layer, it is formed to a thickness of about 200 μm.

In recent years, backlight type liquid crystal panel displays are required to be thinner, and the black sheet is also required to be thinner.
In response to such a demand, when a millable type silicone rubber is used, it is difficult to manufacture a thinner one than before, and it is virtually impossible to satisfy the demand for thinning. On the other hand, in the case of using liquid silicone rubber, repelling and pinholes are likely to occur when trying to form a thin film, and light is not absorbed in the surface, but a portion where light is transmitted is generated, thereby reducing light absorption performance. Will be allowed to.
That is, the conventional black sheet for a backlight type liquid crystal panel display has a problem that it is difficult to reduce the thickness while suppressing a decrease in light absorption performance.

Japanese Patent Laid-Open No. 2001-200221 Japanese Patent Laid-Open No. 10-123964

  The subject of this invention is providing the black sheet | seat for backlight type liquid crystal panel displays which can be reduced in thickness, suppressing the fall of the light absorption performance.

As a result of intensive studies on the reduction of light absorption performance and thinning of the black sheet for a backlight type liquid crystal panel display, the present inventors are colored black separately from the surface layer in the laminated structure of the sheet. The present inventors have found that even if the thickness of the surface layer is reduced by providing a black layer, it is possible to suppress a decrease in light absorption performance, and the present invention has been completed.
That is, in order to solve the above problems, the present invention has a laminated structure, the surface layer is formed of black silicone rubber, and the surface layer is brought into contact with the liquid crystal module surface of the backlight type liquid crystal panel display. This is a black sheet for a backlight type liquid crystal panel display in which the light of the backlight is absorbed by the contacted surface layer, wherein the surface layer is formed using liquid silicone rubber, and the surface layer A black sheet for a backlight type liquid crystal panel display characterized in that at least one black layer colored in black is formed on the back surface side of the front surface layer.

According to the present invention, since the surface layer is formed using liquid silicone rubber, the surface layer can be made thinner than before. In addition to the surface layer, a black layer that is colored black is formed on the back side of the surface layer, so even if repelling or pinholes occur on the surface layer, the repelling or pinhole is transmitted. The absorbed light can be absorbed by another black layer formed on the back side of the surface layer.
That is, the black sheet for a backlight type liquid crystal panel display can be thinned while suppressing a decrease in light absorption performance.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG.
The black sheet 14 for a backlight type liquid crystal panel display in the present embodiment has a laminated structure and includes a surface layer 31 using silicone rubber.
The black sheet 14 for a backlight type liquid crystal panel display has a laminated structure in which a primer layer 32, a black layer 33, a base material layer 34, and an adhesive layer 36 are laminated in this order after the surface layer 31.

The surface layer 31 is formed using liquid silicone rubber, is colored black, and usually has a thickness of 30 to 300 μm.
In addition, as the liquid silicone rubber, a condensation product such as acetone or alcohol is not formed as in the case of the condensation liquid silicone rubber, and the liquid crystal rubber can be prevented from being contaminated. Silicone rubber is preferably used.
The surface layer 31 can be made of black silicone rubber in which 1 to 10% by weight of carbon black is usually contained in silicone rubber.
In the present specification, the liquid silicone rubber is intended to be a silicone rubber exhibiting fluidity at room temperature, and usually indicates a degree of polymerization of about 100 to 2000.

The primer layer 32 is made of a silane coupling agent, and usually has a thickness of 0.1 to 2.0 g / m ² as a dry film.
The silane coupling agent is not particularly limited, and the functional group is vinyl, epoxy, styryl, methacryloxy, acryloxy, amino, ureido, chloropropyl, mercapto, sulfide, Those containing an isocyanate group or the like can be used alone or in combination.

The black layer 33 is formed of a carbon black-containing urethane resin paint containing 1% by weight or more of carbon black, and is usually 1 to 8 μm thick, preferably 2 to 5 μm thick.
The thickness of the black layer 33 made of such a carbon black-containing urethane resin paint is preferably 2 to 5 μm. If the thickness is less than 2 μm, pinholes are generated in the black layer 33 and light is transmitted. The thickness of the black sheet for the backlight type liquid crystal panel display is not only difficult to improve the pinhole suppression effect even if the thickness exceeds 5 μm, but also to improve the light transmission preventing property. This is because the thickness may be increased.
Moreover, it is preferable that this black layer 33 is formed by two or more times of urethane resin coating from the point which suppresses a possibility that a pinhole may be formed and light may permeate | transmit.

The base material layer 34 preferably has a strength that can easily handle the black sheet for a backlight type liquid crystal panel display, such as when a black sheet for a backlight type liquid crystal panel display is attached to a frame material. A synthetic resin film or the like can be used.
Among these, a PET film is preferable because it is excellent in heat resistance and strength and has a low material cost. When this PET film is used for the base material layer, the thickness is usually 25 to 150 μm.
In addition, this PET film may be surface-modified such as corona treatment or may be untreated.

  The said adhesion layer 36 is not specifically limited, For example, it can form in 20-70 micrometers thickness using an acrylic adhesive.

  Next, a method for producing such a black sheet for a backlight type liquid crystal panel display will be described.

First, the black layer 33 is formed on the PET film to be the base material layer 34 by gravure coating. At this time, if necessary, the carbon black-containing urethane resin paint of the black layer 33 may be appropriately diluted with a solvent.
Next, after the black layer 33 is dried, the primer layer 32 is spray-coated. At this time, since the urethane resin paint (black layer 33) is formed on the PET film, repelling of the primer layer 32 can be suppressed as compared with the case where the primer layer 32 is directly formed on the PET film.
Further, a liquid silicone rubber is coated on the primer layer 32 and is heated and cured to form the surface layer 31. At this time, since the primer layer 32 is uniformly formed by the black layer 33, it is possible to suppress the occurrence of repelling and pinholes in the liquid silicone rubber. Silicone rubber has higher wettability to urethane resin than PET, and the black layer 33 can further suppress the occurrence of repelling and pinholes in the surface layer 31.

  Thereafter, a surface protective film 35 is pasted on the surface layer 31 to prevent foreign matters such as dust from adhering to the surface layer 31 before use, and an adhesive layer 36 is formed on the back side of the base material layer 34. Thus, the black sheet 14 for the backlight type liquid crystal panel display is manufactured. If necessary, a silicone surface-treated PET film, a silicone surface-treated kraft paper, or the like can be provided as the separator 37 to protect the adhesive layer 36.

In this embodiment, the black layer using urethane resin is used as an example in that wetting of the primer layer and liquid silicone rubber can be improved to prevent the occurrence of repelling and pinholes in the liquid silicone rubber. Although described, in the present invention, the black layer is not limited to the one using urethane resin.
Moreover, in this embodiment, although the example which formed the black layer between the base material layer and the primer layer was demonstrated, in this invention, without using a primer layer, a surface layer and a base material layer are used. This black layer may be formed between them, and if necessary, it can be provided on the back side of the base material layer. Furthermore, the case where a black film is used for the base material layer and a layer colored in black other than the base material layer and the surface layer is not provided is also within the intended range of the present invention.

EXAMPLES Next, although an Example is given and this invention is demonstrated in more detail, this invention is not limited to these.
Example 1
A urethane resin paint having a carbon black concentration of 3% by weight in a solid content was applied to a PET film having a thickness of 50 μm with a gravure coater so that the thickness would be 1 μm when dried, followed by drying at 120 ° C. for 5 minutes, Under the same conditions, the urethane resin paint was applied and dried, and a black layer having a total thickness of 2 μm was formed by two coats.
Next, a silane coupling agent was applied to the surface of the black layer with a kiss coater so as to be 0.5 g / m ² as a dry film, and dried at 120 ° C. for several tens of seconds to form a primer layer.
Further, a black addition type silicone rubber (containing 5% by weight of carbon black) is applied on the primer layer by a comma direct method, heated at 150 ° C. for 10 minutes to crosslink the black silicone rubber, and a surface having a thickness of 50 μm. A layer was formed to produce a black sheet for a backlight type liquid crystal panel display.
(Example 2)
The back was the same as in Example 1 except that the urethane resin paint was applied and dried to a thickness of 1.5 μm instead of 1 μm when dried, and a black layer with a total thickness of 3 μm was formed by two overcoats. A black sheet for a light-type liquid crystal panel display was produced.
(Comparative Example 1)
A black sheet for a backlight type liquid crystal panel display was manufactured in the same manner as in Example 1 except that the black layer was not formed (without using the urethane resin paint) other than the surface layer made of black silicone rubber.

(Evaluation)
A position of 1 m is provided on the back side of the black sheet for backlight type liquid crystal panel display of each example and comparative example, and a 40 W fluorescent lamp is turned on, and the position 30 cm away from the front side of the black sheet for backlight type liquid crystal panel display The number of bright spots observed per 10 cm × 10 cm of a black sheet for a backlight type liquid crystal panel display was measured. The results are shown in Table 1.

この結果からも、また、表面層とは別に黒色に着色された黒色層が表面層よりも裏面側に形成されていることで表面層にハジキやピンホールなどが生じたとしても、このハジキやピンホール個所を透過した光を表面層の裏面側に形成された別の黒色層で吸収させることができバックライト式液晶パネルディスプレイ用黒色シートを光の吸収性能の低下を抑制しつつ薄型化させ得ることがわかる。

Also from this result, even if a black layer that is colored black separately from the surface layer is formed on the back side of the surface layer, repelling or pinholes may occur in the surface layer. The light transmitted through the pinhole can be absorbed by another black layer formed on the back side of the surface layer, and the black sheet for backlight type liquid crystal panel displays can be made thin while suppressing a decrease in light absorption performance. I know you get.

1 is a schematic cross-sectional view showing a backlight type liquid crystal panel display. The schematic sectional drawing which shows the black sheet for backlight type liquid crystal panel displays of one Embodiment.

Explanation of symbols

  1: liquid crystal module, 2: backlight, 14: black sheet for backlight type liquid crystal panel display, 31: surface layer, 33: black layer, 34: base material layer

Claims (3)

It has a laminated structure, and the surface layer is formed of black silicone rubber. By bringing the surface layer into contact with the liquid crystal module surface of the backlight type liquid crystal panel display, the surface layer is in contact with the surface layer. A black sheet for a backlight type liquid crystal panel display in which light is absorbed,
The surface layer is formed using liquid silicone rubber, and at least one black layer colored black is formed on the back side of the surface layer separately from the surface layer. Black sheet for light-type LCD panel display. The black sheet for a backlight type liquid crystal panel display according to claim 1, wherein a primer layer containing a silane coupling agent is formed on a layer in contact with the surface layer on the back surface side of the surface layer. The black sheet for a backlight type liquid crystal panel display according to claim 2, wherein a black layer using a urethane resin colored in black is formed on a layer in contact with the primer layer on the back side of the primer layer.

Images