JP7269651B2 - Transmitted light sheet and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transmissive light sheet that is installed on the front surface of a lighting panel or the like and used to constitute a light-emitting surface for lighting, and a manufacturing method thereof.

This type of sheet for transmitted light is configured to properly diffuse and transmit light from the back surface such as a backlight. As a nonflammable sheet for transmitted light, the present applicant has previously proposed a translucent or milky-white substrate made of glass cloth coated with a resin layer including a light diffusion layer having light diffusion and light transmission properties. (see Patent Documents 1 and 2, for example). Here, the light diffusing layer is formed by applying a mixture of a base resin and a light diffusing agent having light diffusing properties to the outside of the base material.

JP 2007-203724 A JP 2010-042587 A

By the way, when the lighting panel becomes thin, the distance between the light source such as the LED element built in the lighting panel and the transmitted light sheet installed in front of the lighting panel becomes narrower, and the light emitting surface made of the transmitted light sheet becomes narrower. There is a concern that bright spots appear and the beauty of the light emitting surface is spoiled.

Therefore, in order to avoid such a problem, it is conceivable to increase the light diffusion property of the sheet for transmitted light by thickening the light diffusion layer, but the light diffusion agent for forming the light diffusion layer is expensive. Therefore, if a large amount of such an expensive light diffusing agent is used to increase the thickness of the light diffusing layer, there is a problem that the manufacturing cost rises sharply. Furthermore, the weight of the transmitted light sheet is increased, making it difficult to use it for outdoor signboards and the like.

The present invention has been made in view of the above-mentioned circumstances, and the main problem thereof is to realize high light diffusion while suppressing the increase in manufacturing cost and weight as much as possible, and is suitable for thinning the lighting panel. To provide a sheet for transmitted light and a method for manufacturing the same, which can correspond to

A first characteristic configuration of the present invention is a nonflammable sheet for transmitting light, which is formed into a sheet shape having light diffusibility and light transparency by coating a base material made of nonflammable glass cloth with a resin layer. ,
The resin layer includes, as a light diffusing layer for diffusing light, a foamed light diffusing layer obtained by blending a light diffusing agent having a light diffusing property and a foaming agent having a foaming property into a base resin and foaming. .

According to this configuration, the light diffusion layer includes a foamed light diffusion layer obtained by blending a light diffusion agent having a light diffusion property and a foaming agent having a foaming property into a base resin and foaming it. Only the thickness of the light diffusion layer can be increased. As a result, it is possible to improve the light diffusion performance of the light diffusion layer while suppressing an increase in the amount of the light diffusion agent used and an increase in the weight of the light diffusion layer.
Therefore, it is possible to achieve high light diffusibility while minimizing an increase in manufacturing cost and weight, and to appropriately cope with thinning of the lighting panel.

In the second characteristic configuration of the present invention, the light diffusion layer includes an inner light diffusion layer disposed on the inner side of the base material and an outer light diffusion layer disposed on the outer side of the inner light diffusion layer. prepared,
The inner light diffusion layer is configured as a non-foamed light diffusion layer that does not contain the foaming agent,
The outer light diffusing layer is configured as the foamed light diffusing layer obtained by blending and foaming the foaming agent.

According to this configuration, the inner light diffusion layer constituting the inner portion of the light diffusion layer is a non-foamed light diffusion layer, and the outer light diffusion layer constituting the outer portion of the light diffusion layer is a foamed light diffusion layer. , the inner non-foamed light diffusion layer can be appropriately configured without being pushed out from the inside by the foamed light diffusion layer, while the outer foamed light diffusion layer is not constrained from the outside by the non-foamed light diffusion layer. It can be foamed and configured appropriately. Therefore, a light diffusing layer having a sufficient thickness can be appropriately configured to satisfactorily realize high light diffusibility.

A third characteristic configuration of the present invention is that the foamed light diffusion layer is formed by blending the base resin with a hollowing agent.

According to this configuration, since the foamed light diffusion layer included in the light diffusion layer is further blended with the hollowing agent, the thickness of the light diffusion layer can be increased by the amount of the hollowing agent mixed in, and further favorable Light diffusion performance can be achieved.

In the fourth characteristic configuration of the present invention, the inner light diffusion layer as the non-foamed light diffusion layer is composed of titanium oxide as the light diffusion agent and a blooming agent that lowers its color temperature,
The outer light diffusing layer as the foamed light diffusing layer is formed by blending silica as the light diffusing agent.

According to this configuration, the inner light diffusing layer as the non-foamed light diffusing layer contains titanium oxide as a light diffusing agent and a blooming agent, thereby achieving good light diffusibility due to titanium oxide and titanium oxide. It is possible to mitigate the increase in color temperature. The outer light diffusion layer, which is a foamed light diffusion layer, contains silica, which has a strong white component, as a light diffusion agent. In a form in which the diffusion layer is coated from the outside, the light diffusion layer composed of the inner light diffusion layer and the outer light diffusion layer can have an appropriate white color temperature.

A fifth characteristic configuration of the present invention is a method for manufacturing a transmissive light sheet according to any one of the first to fourth characteristic configurations,
a coating step of forming a pre-foaming light diffusion layer that has not yet been foamed by applying a mixture of the light diffusing agent and the thermoplastic foaming agent to the base resin to the outside of the base material;
a foaming step of heating and foaming the pre-foaming light diffusion layer formed in the coating step to form the foamed light diffusion layer.

According to this configuration, by performing the application step and applying the mixture of the light diffusing agent and the thermoplastic foaming agent to the base resin on the outside of the base material, the foamed material that has not yet been foamed on the outside of the base material is applied. A semi-finished product in which the front light diffusion layer is formed can be configured. Then, a foaming step is performed to heat and foam the pre-foaming light diffusion layer on the outside of the base material, thereby easily manufacturing a sheet for transmitting light in which the foamed light diffusion layer is formed on the outside of the base material. can be done.

Cross-sectional view of sheet for transmitted light Cross-sectional view showing a method for manufacturing a sheet for transmitted light (a) Partially broken plan view of sheet for transmitted light, (b) Cross-sectional view of glass yarn

Embodiments of the transmissive light sheet of the present invention and a method for manufacturing the same will be described with reference to the drawings.
First, the transmitted light sheet will be described with reference to FIGS. 1 and 3. FIG.
The transmitted light sheet 1 is installed on the front surface of a lighting panel or the like and used for purposes such as lighting. By using the light source of the illumination panel as a backlight to cause the surface of the transmitted light sheet 1 to emit light, the surface of the transmitted light sheet 1 may emit light to brightly illuminate the surroundings. An image applied by printing or the like can be displayed as an advertisement.

The transmitted light sheet 1 is formed into a nonflammable sheet having light diffusibility and translucency by covering a base material 2 made of a nonflammable glass cloth with a resin layer 3 . The base material 2 made of glass cloth is constructed by weaving yarns GY in which a large number of glass filaments gf (in other words, glass single fibers, see FIG. 3(b)) are bundled. The resin layer 3 is a thin layer that does not affect the non-combustibility of the sheet for transmitting light 1, and the front side and the back side that are separated from the inner side (the center side in the thickness direction) of the substrate 2 side (the center side in the thickness direction) and the outer side (away from the center side in the thickness direction). ), a first layer 31, a second layer 32, and a third layer 33 are stacked.

The first layer 31 serves to seal the glass cloth (prevent fraying), and is formed as a sealing layer A by impregnating the base material 2 with a urethane-based resin or the like.

The second layer 32 is an inner light diffusion layer that constitutes the inner portion of the light diffusion layer that diffuses while transmitting the light from the light source, and contains a light diffusion agent such as titanium oxide in a base resin such as a urethane resin. However, a non-foamed light diffusion layer B is formed without blending a foaming agent having a foaming property. The second layer 32 is blended with a blue pigment (an example of a blooming agent) that lowers the color temperature in order to suppress an increase in the color temperature due to the contained titanium oxide.

The third layer 33 is an outer light diffusing layer constituting an outer part of the light diffusing layer that diffuses while transmitting the light from the light source. The foamed light diffusion layer C is formed by blending silica, which has a strong element, and further blending and foaming a foaming agent having a foaming property. For the third layer 33, an acrylic resin containing a hollowing agent is used as part of the base resin. The thickness of the third layer 33 is configured to be larger than the thickness of the second layer 32, for example.

In this embodiment, a thermoplastic (thermally expansive) foaming agent that foams (expands) when heated is used as the foaming agent, and is blended in the third layer 33 by about 5 to 10%, for example. As the foaming agent, for example, a mixture of isopentane and silicon dioxide can be suitably used.

Therefore, the thickness of the light diffusing layer can be increased by the amount of foaming by the foaming agent, and high light diffusibility can be achieved while suppressing an increase in the amount of the light diffusing agent used and an increase in weight. Furthermore, in the present embodiment, the thickness of the light diffusion layer is increased by the amount of the hollowing agent mixed thereinto, thereby achieving even higher light diffusion. Therefore, the transmitted light sheet 1 achieves high light diffusibility while minimizing increases in manufacturing cost and weight, and can appropriately cope with thinning of the lighting panel.

Incidentally, the transmitted light sheet 1 can have a thickness of about 0.2 to 0.35 mm, for example, and the total thickness of the base material 2 and the front and back first layers 31 is 0.03 mm. The thickness of the second layer 32 on the front and back can be about 0.015 to 0.045 mm, and the thickness of the third layer 33 on the front and back can be about 0.05 to 0.12 mm.

Next, a method for manufacturing the transmissive light sheet 1 will be described with reference to FIGS. 1 and 2. FIG.
In this manufacturing method, the above-described sheet for transmitting light 1 is manufactured by sequentially performing the coating process and the foaming process described below.

(Coating process)
As shown in FIG. 2, in this coating step, a first layer 31 as a filling layer A is formed by coating and impregnating a urethane-based resin or the like on the outside of the base material 2 .
A second layer 32 as a non-foamed light diffusion layer B is applied to the first layer 31 on the outside of the substrate 2 by applying a light diffusing agent such as titanium oxide to a base resin such as a urethane-based resin. to form
Furthermore, by applying a foaming agent and a light diffusing agent such as silica mixed with a base resin such as vinyl chloride or acrylic resin to the second layer 32 on the outside of the base material 2, the foamed material that has not yet been foamed can be removed. A pre-foaming light diffusion layer C′, which is the previous foamed light diffusion layer C, is formed.
Thus, the semi-finished product 1' having the pre-foaming light diffusion layer C' formed on the outermost side can be obtained.

(foaming process)
In this foaming step, the outside of the semi-finished product 1' having the pre-foaming light diffusion layer C' formed on the outside thereof is heated by a heater or the like, so that the pre-foaming The light diffusion layer C' is foamed to form a foamed light diffusion layer C as shown in FIG.
In this manner, a finished product (sheet for transmitted light 1) having the foamed light diffusion layer C formed on the outermost side can be easily obtained.

[Another embodiment]
Another embodiment of the present invention will be described. It should be noted that the configuration of each embodiment described below is not limited to being applied alone, and can be applied in combination with the configurations of other embodiments.

(1) In the above embodiment, the substrate 2 made of glass cloth is coated with three layers (an example of multiple layers) of the resin layer 3, but one, two, or four or more resin layers 3 may be coated.

(2) In the above embodiment, the light diffusion layer is formed on both the front side and the back side of the substrate 2, but the light diffusion layer is formed only on one of the front side and the back side of the substrate 2. may be

(3) In the above embodiment, the case where the light diffusion layer is composed of a plurality of layers of the non-foamed light diffusion layer B and the foamed light diffusion layer C is shown as an example. may be In that case, for example, the foamed light diffusing layer C can be configured by blending one or both of titanium oxide and silica as a light diffusing agent and a foaming agent into a base resin.

(4) Specific configurations such as the types of the light diffusing agent, the foaming agent, the hollowing agent, etc. can be appropriately changed according to the implementation environment of the sheet for transmitted light 1 and the like.

Although the embodiments of the present invention have been described above, the present invention is by no means limited to such embodiments, and can of course be implemented in various forms without departing from the gist of the present invention.

1 sheet for transmitted light 2 base material 3 resin layer B non-foamed light diffusion layer C foamed light diffusion layer C' pre-foamed light diffusion layer

Claims (3)

A nonflammable sheet for transmitting light, which is formed into a sheet shape having light diffusibility and light transparency by coating a base material made of nonflammable glass cloth with a resin layer,
The resin layer includes a filling layer that is placed on the innermost side in contact with the base material to seal the glass cloth, and a light diffusion layer that is placed outside the filling layer and diffuses light. be
The light diffusion layer includes a foamed light diffusion layer obtained by blending a light diffusion agent having light diffusion properties and a foaming agent having foaming properties into a base resin and foaming them,
As the light diffusion layer, an inner light diffusion layer disposed on the inner side of the base material and an outer light diffusion layer disposed on the outer side of the inner light diffusion layer are provided,
The inner light diffusion layer is configured as a non-foamed light diffusion layer that does not contain the foaming agent,
The outer light diffusion layer is a transmitted light sheet configured as the foamed light diffusion layer formed by blending and foaming the foaming agent. The inner light diffusion layer as the non-foamed light diffusion layer is composed of titanium oxide as the light diffusion agent and a blooming agent that lowers its color temperature,
2. The transmitted light sheet according to claim 1, wherein said outer light diffusion layer as said foamed light diffusion layer is formed by blending silica as said light diffusion agent. A method for manufacturing a sheet for transmitted light according to claim 1 or 2,
a coating step of forming a pre-foamed light diffusion layer that has not yet been foamed by applying a mixture of the light diffusion agent and the thermoplastic foaming agent to the base resin to the outside of the non-foamed light diffusion layer ;
a foaming step of heating and foaming the pre-foaming light diffusion layer formed in the coating step to form the foamed light diffusion layer.

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