JPH0780956A - Production of light scattering material - Google Patents

Abstract

PURPOSE:To obtain a light scattering material enhanced in light scattering rate by forming a resin film and exposing the film to a poor solvent having a b.p. higher than that of a good solvent to dry the same to vaporize the solvent and forming the resin film having fine voids on a substrate. CONSTITUTION:Polyethylene dissolved in a good solvent 3, for example, benzene, toluene or ethyl acetate and an acrylic resin soln. are applied or printed on a substrate to form a resin film l. The resin film 1 is exposed to a poor solvent 4 having a b.p. higher than that of the good solvent, for example, methanol, n-butanol or diacetone alcohol before the good solvent 3 in the resin film 1 is perfectly dried. The good solvent 3 and the poor solvent 4 are successively vaporized by drying the resin film to form the resin film having a large number of non-spherical continuous fine voids on the substrate to obtain a light scattering material. Herein, when the substrate is a light guide plate, as the material quality thereof, an acrylic resin, polycarbonate or a polyvinyl chloride resin is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a light scattering material having a high light scattering rate.

The backlight of a liquid crystal display is required to be thin and to emit high brightness and uniform light.
As a backlight of such a liquid crystal display, a line light source is arranged on the side of a transparent light guide plate, and a light scattering reflection portion having a gradation pattern whose formation density changes according to the distance from the line light source is provided on the back surface of the light guide plate. The edge light type surface light source device provided is often used.

The light-scattering / reflecting portion scatters and reflects upwardly the light that has entered the light guide plate from the linear light source and emits it from the upper surface of the light guide plate. Therefore, increasing the light-scattering rate of the light-scattering / reflecting portion is an important point for increasing the brightness of the surface light source device.

In some surface light source devices, a diffusion plate is arranged on the front side of the light guide plate. The diffusion plate scatters the light emitted from the light guide plate to eliminate the brightness difference between the portion where the light scattering reflection portion is formed and the portion where the light scattering reflection portion is not formed, and obtains a uniform light emitting surface.

[0005]

2. Description of the Related Art Conventionally, as a method of forming a light-scattering / reflecting portion on the back surface of a light guide plate, an ink mixed with light-scattering fine particles such as white pigment or glass beads is used to guide the light-scattering layer in a gradation pattern. A method of printing directly on the back surface of the light plate, or a light scattering layer with a gradation pattern is printed directly on the back surface of the light guide plate using ink mixed with a gas generating substance, and then a large number of air bubbles are enclosed inside by foaming by light irradiation or heating. There was a method of forming the resin layer.

As another method of forming the light-scattering / reflecting portion on the back surface of the light guide plate, after providing a light-transmitting layer having a gradation pattern whose formation density changes according to the distance from the linear light source on the back surface of the light guide plate. , A method in which a film coated with ink mixed with light scattering fine particles such as white pigments and glass beads is laminated on the back surface of the light guide plate, or light having a gradation pattern in which the formation density changes according to the distance from the linear light source. After providing the transparent layer on the back surface of the light guide plate, there is a method of coating the entire surface with an ink mixed with a gas generating substance and laminating a film having a coating film foamed by light irradiation or heating on the back surface of the light guide plate.

In the case of a diffusion plate, a film coated with the above-mentioned ink mixed with the above light-scattering fine particles,
In some cases, a film in which an ink mixed with a gas generating substance is applied over the entire surface and a coating film is foamed by light irradiation or heating is used.

[0008]

However, the above-mentioned prior art has the following problems.

That is, in the method of using an ink mixed with light-scattering fine particles such as white pigment and glass beads, the content of the light-scattering fine particles is limited in order to obtain printability as an ink, and high light No scattering rate was obtained.
Further, since the light-scattering fine particles have a large particle diameter, the unevenness of the coating film obtained by mixing the light-scattering fine particles becomes rough, and thus a high light-scattering rate cannot be obtained.

Further, in the method of foaming the coating film by light irradiation or heating using an ink containing a gas generating substance,
The generated bubbles are formed almost in a spherical shape. In other words, since the surface area of the bubbles is very small, the surface area of the interface between the bubbles and the resin, that is, the light scattering interface does not become large. Therefore, a high light scattering rate was not obtained.

In addition, when trying to generate bubbles with a high density, the coating layer swells due to the generation of bubbles, resulting in extremely poor pattern accuracy. For example, even if dot gradation is printed, a faithful pattern can be reproduced. This causes uneven brightness. Further, the film quality becomes extremely brittle due to foaming. Therefore, the foam density is limited and a high light scattering rate cannot be obtained.

Therefore, an object of the present invention is to solve the above problems and to provide a light scattering material having a high light scattering rate.

[0013]

In order to achieve the above object, in the method for producing a light-scattering material of the present invention, a resin solution dissolved in a good solvent is applied or printed on a substrate to form a resin film. Before the good solvent in the resin film is completely dried, the resin film is exposed to a poor solvent having a boiling point higher than that of the good solvent, and then the resin film is dried to vaporize the good solvent and the poor solvent in this order. The light-scattering material was formed so that a resin coating having a spherical shape and a large number of continuous fine pores was formed on the substrate.

Further, in the method for producing a light-scattering material of the present invention, a resin liquid dissolved in a good solvent is applied or printed on a substrate to form a resin film, and before the good solvent in the resin film is completely dried. The resin coating is exposed to a poor solvent which has a boiling point equal to or lower than that of the good solvent and is excessive with respect to the good solvent, and then the resin coating is dried to vaporize the poor solvent to form a large number of non-spherical and continuous particles. A resin coating having fine pores was formed on the substrate so as to obtain a light scattering material.

Further, in the method for producing a light-scattering material of the present invention, a resin liquid dissolved in a mixed solution of a good solvent and a poor solvent having a boiling point higher than that of the good solvent is applied or printed on a substrate to form a resin film. By forming and drying this resin film, a good solvent and a poor solvent are vaporized in this order to obtain a light-scattering material with a non-spherical and continuous resin film having a large number of fine pores formed on the substrate. Configured to.

The present invention will be described in more detail below with reference to the drawings.

1 to 11 are schematic views showing an embodiment of the method for manufacturing a light scattering material according to the present invention, and FIGS. 12 to 14 are sectional views showing a surface light source device using the light scattering material according to the present invention. Is. 1 is a resin film, 2 is a resin, 3 is a good solvent, 4 is a poor solvent, 5 is an agglomerated resin phase, 6 is a poor solvent phase, 7 is a void, 8 is a resin film having fine pores, 9 is a light guide plate, 10 is a line light source,
11 is a light scattering layer, 121, 122 and 123 are light scattering materials,
13 is a light transmissive layer, and 14 is a support.

According to the present invention, the light-scattering materials 121, 122, 123 having the resin coating 8 which is non-spherical and has a large number of continuous fine pores formed on the substrate are obtained as follows.

<Method 1> The substrate may be the light guide plate 9 (see FIG. 12) or the support 14 laminated on the light guide plate 9 (see FIGS. 13 and 14).

When the light-scattering layer 11 having a gradation pattern whose area ratio changes according to the distance from the linear light source 10 is directly formed on the back surface of the light guide plate 9 to form the light-scattering material 121,
The light guide plate 9 serves as a base (see FIG. 12). As the material of the light guide plate 9, resin such as acrylic, polycarbonate, polyvinyl chloride, or glass is used.

The light-transmitting layer 13 having a gradation pattern whose area ratio changes according to the distance from the linear light source 10.
Is formed on the back surface of the light guide plate 9 and the support 14 having the light scattering layer 11 applied to the entire surface is laminated on the surface having the transparent layer 13 using the light guide plate 9 as the light scattering material 122 (see FIG. 13), or When the support 14 on which the scattering layer 11 is coated and formed is laminated on the front side of the light guide plate 9 as the light scattering material 123 (see FIG. 14), the support 14 serves as a base. Support 14
Is made of a film or a resin thin plate, and a resin such as acrylic or polyethylene terephthalate is used as the material thereof.

First, a resin solution obtained by dissolving the resin 2 in the good solvent 3 is applied or printed on these substrates (see FIG. 1). The good solvent 3 refers to a solvent having a large ability to dissolve a solute. On the contrary, a solvent having a small ability to dissolve a solute is referred to as a poor solvent 4. Examples of the good solvent 3 are aromatic hydrocarbons such as benzene, toluene and xylene, esters such as ethyl acetate and butyl acetate, acetone, methyl ethyl ketone, ketones such as cyclohexanone, carbon tetrachloride and dichloroethane for polystyrene resin. In addition to the halogenated hydrocarbons, tetrahydrofuran, cyclohexane, etc. are used. For acrylic resins, aromatic hydrocarbons such as benzene, toluene, xylene, esters such as ethyl acetate and butyl acetate, ketones such as acetone, methyl ethyl ketone, cyclohexanone, carbon tetrachloride, halogenated hydrocarbons such as dichloroethane. Besides, chloroform is used. Of course, resin 2 other than the polystyrene resin and acrylic resin described above
Also, the good solvent 3 is appropriately selected. Appropriate coating and printing methods may be selected depending on the required film thickness and degree of pattern accuracy. For example, coating methods such as bar coating, roll coating and dip coating, and printing methods such as screen, gravure and offset are used. it can.

Next, before the good solvent 3 in the resin coating film 1 is completely dried, the resin coating film 1 is subjected to a poor solvent 4 having a boiling point higher than that of the good solvent 3.
Expose inside. Examples of the poor solvent 4 include methanol, n-butanol, n-octanol, ethylene glycol, diacetone alcohol, and polystyrene resin.
Alcohol such as methoxyethanol is used. For the acrylic resin, diacetone alcohol, alcohol excluding methoxyethanol and the like are used. Further, the poor solvent 4 is appropriately selected for the resin 2 other than the polystyrene resin and the acrylic resin.
The boiling points of the good solvent 3 and the poor solvent 4 are relative to each other. For example, the good solvent 3 and the poor solvent 4 for the acrylic resin may be a combination of diethylbenzene and n-octanol having a higher boiling point. It As the good solvent 3 and the poor solvent 4 for the polystyrene resin, a combination of xylene and n-hexanol having a higher boiling point or a combination of tetrahydrofuran and n-butanol having a higher boiling point is used. The method of exposing the resin coating film 1 to the poor solvent 4 having a boiling point higher than that of the good solvent 3 may be, for example, immersing the substrate on which the resin coating film 1 is formed in a liquid tank containing the poor solvent 4, or showering the surface of the resin coating film 1. A method of exposing the poor solvent 4 to spraying is used. At this time, the resin coating 1
The good solvent 3 gradually dissolves out from the inside, and conversely, the poor solvent 4 having a higher boiling point than the good solvent 3 gradually penetrates into the resin coating 1 (see FIG. 2), and the resin coating 1 is good with the resin 2. The layer changes to a layer composed of the solvent 3 and the poor solvent 4 having a higher boiling point than the good solvent 3 (see FIG. 3).

Next, the resin film 1 is dried to first vaporize the good solvent 3 (see FIG. 4). Good solvent 3
When the resin is vaporized, the resin 2 in the resin coating film 1 cannot be completely dissolved in the poor solvent 4 having a boiling point higher than that of the good solvent 3 and agglomerates and precipitates, so that the agglomerated resin phase 5 and the poor solvent phase 6 are separated into two phases. Raise (see Figure 5).

When it is further dried to vaporize the poor solvent 4 having a higher boiling point than the good solvent 3 (see FIG. 6), the poor solvent 4 having a higher boiling point than the good solvent 3 is left behind, and the voids 7 remain, thus forming a non-spherical shape. Further, the resin coating film 8 has a large number of continuous fine pores (see FIG. 7).

As another method for obtaining the light scattering material, there are the following methods 2 and 3.

<Method 2> First, in the same manner as in Method 1, a resin solution in which the resin 2 is dissolved in the good solvent 3 is applied or printed on the substrate (see FIG. 8).

Next, before the good solvent 3 in the resin coating 1 is completely dried, the resin coating 1 is equal to or better than the good solvent 3.
It is exposed to the poor solvent 4 having a lower boiling point and an excess of the good solvent 3. The reason why the excess amount of the poor solvent 4 is required with respect to the good solvent 3 is that when the boiling point of the poor solvent 4 is equal to or lower than that of the good solvent 3, the good solvent 3 in the resin film 1 is replaced with the poor solvent 3. If not sufficiently replaced with 4, the poor solvent 4 will be vaporized before the good solvent 3 during drying, and only the good solvent 3 will be the resin coating 1.
This is because the resin layer 8 having fine pores remaining therein cannot be formed. The method of exposing to the poor solvent 4 which is equivalent to the good solvent 3 or has a lower boiling point than the good solvent 3 and an excess amount with respect to the good solvent 3 is, for example, the formation of the resin film 1 in a liquid tank containing an excess amount of the poor solvent 4. A method is used in which the formed substrate is dipped, or the surface of the resin film 1 is showered or sprayed with an excess amount of the poor solvent 4. At this time, the good solvent 3 gradually dissolves out of the resin coating 1, and on the contrary, is equal to or better than the good solvent 3.
The poor boiling solvent 4 having a lower boiling point gradually permeates into the resin coating film 1 (see FIG. 9), and finally the resin coating film 1 forms the resin 2 and the poor solvent 4.
It changes into a layer consisting of and. As a result, the resin 2 in the resin coating film 1 cannot be completely dissolved in the poor solvent 4 and aggregates and precipitates, causing two-phase separation between the aggregated resin phase 5 and the poor solvent phase 6 (see FIG. 10).

Finally, when the resin coating film 1 is dried to vaporize the poor solvent 4 (see FIG. 11), after the poor solvent 4 flies away, voids 7 remain, and a large number of non-spherical and continuous fine holes are formed. (See FIG. 7).

<Method 3> First, a resin solution in which a resin 2 is dissolved in a mixed solution of a good solvent 3 and a poor solvent 4 having a boiling point higher than that of the good solvent 3 is applied or printed on a substrate (see FIG. 3). . As the good solvent 3 and the poor solvent 4 having a boiling point higher than that of the good solvent 3, the same one as in Method 1 can be used.

Next, by drying the resin film 1 in the same manner as in Method 1, first the good solvent 3 is vaporized (see FIG. 4), and the resin film 1 is separated into two phases, an agglomerated resin phase 5 and a poor solvent phase 6. (See FIG. 5).

When the poor solvent 4 is vaporized by further drying (see FIG. 6), the voids 7 remain after the poor solvent 4 flies away,
The resin coating 8 is non-spherical and has a large number of continuous fine pores (see FIG. 7).

The light-scattering materials produced by the methods 1 to 3 have an average of fine pores depending on the combination of the resin 2, the good solvent 3 and the poor solvent 4, the mixing ratio, the coating film thickness, and the drying temperature. The diameter, shape and density can be adjusted to set the conditions for light scattering and light transmission.

[0034]

EXAMPLES Examples of the method for producing the light-scattering material of the present invention will be shown below.

Example 1 A resin liquid having the following composition consisting of a resin and a good solvent was coated on a substrate made of a transparent acrylic resin plate having a thickness of 1 mm with a bar coater. Acrylic resin (Mitsubishi Rayon Co., Ltd., BR-85) 20 parts by weight Cyclohexanone (good solvent) 80 parts by weight

Immediately after coating, the substrate on which the resin film is formed is treated with n-octanol (poor solvent) having a boiling point higher than that of a good solvent.
It was immersed in the solution, and cyclohexanone (good solvent) and n-octanol (poor solvent) were partially replaced, and the resin coating was formed into a layer composed of the resin, the good solvent, and the poor solvent having a boiling point higher than that of the good solvent.
Then, by drying in an oven at 50 ° C. for 30 minutes, cyclohexanone (good solvent) and n-octanol (poor solvent) were vaporized in this order to obtain a light scattering material.

The resin film having fine pores formed on the substrate by drying was white and opaque, and the film thickness was 25 μm. When observing the resin coating with a microscope, the average diameter was 0.
There were dense 4 μm pores.

The light-scattering material thus obtained was laminated on the light-transmitting layer having a gradation pattern provided on the back surface of the light guide plate to form the light-scattering / reflecting portion.
Since the light scattering rate is high, the brightness at the exit surface of the light guide plate is improved.

Example 2 On a substrate made of a transparent acrylic resin plate having a thickness of 1 mm, a resin liquid having the following composition consisting of a resin and a good solvent was screen printed with 200 lines to form circular dot gradations having a pitch of 1.5 mm. Printed on a pattern. Polystyrene resin (degree of polymerization about 1400) 25 parts by weight Butyl acetate (good solvent) 75 parts by weight

After leveling at room temperature for 2 minutes after printing, the substrate with the resin coating formed thereon is dipped in ethylene glycol monoacetate (poor solvent) having a boiling point higher than that of a good solvent to obtain butyl acetate (good solvent) and ethylene glycol monoacetate. Acetate (poor solvent) was partially replaced, and the resin coating was formed into a layer composed of a resin, a good solvent, and a poor solvent having a boiling point higher than that of the good solvent. Then, by drying in an oven at 50 ° C. for 30 minutes, butyl acetate (good solvent) and ethylene glycol monoacetate (poor solvent) were vaporized in this order to obtain a light scattering material.

The resin film having fine pores formed in a gradation pattern on the substrate by drying was white and opaque and had a film thickness of 20 μm. When the resin coating film was observed with a microscope, fine pores having an average diameter of 0.7 μm were densely present.

When the light-scattering material thus obtained was used as a light guide plate, the light-scattering rate was high, so that the brightness at the exit surface of the light-guide plate was improved.

Example 3 A resin liquid having the following composition consisting of a resin and a good solvent was applied by a bar coater onto a substrate made of a transparent acrylic resin plate having a thickness of 1 mm. Acrylic resin (Mitsubishi Rayon Co., Ltd., BR-85) 9 parts by weight Ethyl acetate (good solvent) 91 parts by weight

Immediately after coating, the substrate on which the resin film is formed is treated with n-pentanol (poor solvent) having a boiling point higher than that of a good solvent.
It was immersed in the solution and ethyl acetate (good solvent) and n-pentanol (poor solvent) were partially replaced, and the resin coating was formed into a layer composed of the resin, the good solvent, and the poor solvent having a boiling point higher than that of the good solvent. Then, by drying in an oven at 50 ° C. for 30 minutes, ethyl acetate (good solvent) and n-pentanol (poor solvent) were vaporized in this order to obtain a light scattering material.

The resin film having fine pores formed on the substrate by drying was milky white translucent and had a film thickness of 1.8 μm. When observing the resin coating with a microscope, the average diameter is
Micropores of 1.5 μm were densely present.

When the light-scattering material thus obtained was used as a diffusing plate, the light-scattering rate was high, so that the brightness at the exit surface of the diffusing plate was uniform.

Example 4 A resin liquid having the following composition consisting of a resin and a good solvent was coated on a substrate made of a transparent acrylic resin plate having a thickness of 1 mm with a bar coater. Polystyrene resin (degree of polymerization about 1400) 30 parts by weight Toluene (good solvent) 70 parts by weight

Immediately after coating, the substrate on which the resin film is formed has a boiling point lower than that of the good solvent and is excessive with respect to the good solvent.
Immerse in n-propanol (poor solvent) for 5 minutes to sufficiently replace toluene with n-propanol (poor solvent), then dry in an oven at 50 ° C for 30 minutes to vaporize n-propanol (poor solvent). Then, a light scattering material was obtained.

The resin film having fine pores formed on the substrate by drying was white and opaque and had a film thickness of 30 μm. When observing the resin coating with a microscope, the average diameter was 0.
There were dense 5 μm pores.

When the light-scattering material thus obtained is laminated on the light-transmitting layer having a gradation pattern provided on the back surface of the light guide plate, the light scattering rate is high, so that the brightness on the exit surface of the light guide plate is high. Has improved.

Example 5 On a substrate made of a transparent acrylic resin plate having a thickness of 1 mm, a resin liquid having the following composition consisting of a resin and a good solvent was screen printed with 200 lines to form circular dot gradations having a pitch of 1.5 mm. Printed on a pattern. Acrylic resin (Mitsubishi Rayon Co., Ltd., BR-85) 20 parts by weight Diacetone alcohol (good solvent) 80 parts by weight

After leveling at room temperature for 2 minutes after printing, the substrate on which the resin coating is formed is dipped in n-hexanol (poor solvent) having a boiling point lower than that of the good solvent and an excess amount relative to the good solvent for 30 seconds. Acetone alcohol (good solvent) and n-hexanol (poor solvent) were sufficiently exchanged, and then dried in an oven at 50 ° C for 30 minutes to vaporize n-hexanol (poor solvent) to obtain a light scattering material.

The resin film having fine pores formed in a gradation pattern on the substrate by drying was white and opaque and had a film thickness of 15 μm. When the resin coating film was observed with a microscope, fine pores having an average diameter of 0.3 μm were densely present.

When the light-scattering material thus obtained was used as a light guide plate, the light-scattering rate was high, so that the brightness at the exit surface of the light-guide plate was improved.

Example 6 A resin liquid having the following composition consisting of a resin and a good solvent was applied on a substrate made of a transparent acrylic resin plate having a thickness of 1 mm by a bar coater. Acrylic resin (Mitsubishi Rayon Co., Ltd., BR85) 7 parts by weight Butyl acetate (good solvent) 93 parts by weight

Immediately after coating, the substrate on which the resin film is formed has a boiling point lower than that of the good solvent and is excessive with respect to the good solvent.
Immerse in n-butanol (poor solvent) for 20 seconds to sufficiently replace butyl acetate (good solvent) with n-butanol (poor solvent), then dry in an oven at 50 ° C for 30 minutes to dry n-butanol (poor solvent). The poor solvent) was vaporized to obtain a light scattering material.

The resin coating having fine pores formed on the substrate by drying was milky white translucent and had a thickness of 1.5 μm. When the resin coating film was observed with a microscope, fine pores having an average diameter of 1 μm were densely present.

When the light-scattering material thus obtained was used as a diffusing plate, the light-scattering rate was high, and the brightness on the exit surface of the diffusing plate was uniform.

Example 7 A resin liquid of the following composition comprising a resin, a good solvent, and a poor solvent having a boiling point higher than that of the good solvent was coated on a substrate made of a transparent acrylic resin plate having a thickness of 1 mm by a bar coater. Polystyrene resin (degree of polymerization about 1400) 20 parts by weight xylene (good solvent) 50 parts by weight n-hexanol (poor solvent) 30 parts by weight

After applying the resin solution, it is dried in an oven at 50 ° C. for 30 minutes to obtain xylene (good solvent), n-
Hexanol (poor solvent) was vaporized in this order to obtain a light scattering material.

The resin film having fine pores formed on the substrate by drying was white and opaque, and the film thickness was 30 μm. When observing the resin coating with a microscope, the average diameter was 0.
There were dense 5 μm pores.

When the light-scattering material thus obtained was laminated on the light-transmitting layer having a gradation pattern provided on the back surface of the light guide plate, the light-scattering rate was high, so that the brightness at the exit surface of the light-guide plate was high. Improved.

Example 8 A resin solution of the following composition comprising a resin, a good solvent, and a poor solvent having a boiling point higher than that of a good solvent was screen-printed with 200 lines on a substrate made of a transparent acrylic resin plate having a thickness of 1 mm. Printed on a circular dot gradation pattern with a pitch of 1.5 mm. Acrylic resin (Mitsubishi Rayon Co., Ltd., BR85) 20 parts by weight Diethylbenzene (good solvent) 60 parts by weight n-Octanol (poor solvent) 20 parts by weight

After printing, by drying in an oven at 60 ° C. for 1 hour, diethylbenzene (good solvent) and n-octanol (poor solvent) were vaporized in this order to obtain a light scattering material.

The resin film having fine pores formed in a gradation pattern on the substrate by drying was white and opaque and had a film thickness of 30 μm. When the resin film was observed with a microscope, fine pores having an average diameter of 0.3 μm were densely present.

When the light-scattering material thus obtained was used as a light guide plate, the light-scattering rate was high, so that the brightness on the exit surface of the light-guide plate was improved.

Example 9 A resin solution of the following composition comprising a resin, a good solvent, and a poor solvent having a boiling point higher than that of the good solvent was coated on a substrate made of a transparent polyethylene terephthalate resin having a thickness of 0.5 mm by a bar coater. Polystyrene resin (degree of polymerization about 1400) 9 parts by weight Tetrahydrofuran (good solvent) 67 parts by weight n-Butanol (poor solvent) 24 parts by weight

After printing, tetrahydrofuran (good solvent) and n-butanol (poor solvent) were vaporized in this order by drying in an oven at 50 ° C. for 30 minutes to obtain a light scattering material.

The resin film having fine pores formed by drying was milky white translucent and had a film thickness of 2.0 μm.
When the resin coating film was observed with a microscope, fine pores having an average diameter of 1 μm were densely present.

When the light-scattering material thus obtained was used as a diffusing plate, the light-scattering rate was high, and the brightness on the exit surface of the diffusing plate was uniform.

[0071]

According to the method for producing a light-scattering material of the present invention, a resin layer having a large number of non-spherical and continuous fine pores can be formed on a substrate.

Therefore, since the area of the light-scattering interface between the resin and the fine pores in the resin layer is large, a light-scattering material having a high light-scattering rate can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 2 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 3 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 4 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 5 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 6 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 7 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 8 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 9 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 10 is a schematic view showing an example of the method for manufacturing a light-scattering material according to the present invention.

FIG. 11 is a schematic view showing an example of a method for manufacturing a light-scattering material according to the present invention.

FIG. 12 is a sectional view showing a surface light source device using a light scattering material according to the present invention.

FIG. 13 is a sectional view showing a surface light source device using a light scattering material according to the present invention.

FIG. 14 is a sectional view showing a surface light source device using a light scattering material according to the present invention.

[Explanation of symbols]

 1 Ink Layer 2 Resin 3 Good Solvent 4 Poor Solvent 5 Aggregated Resin Phase 6 Poor Solvent Phase 7 Micropores 8 Resin Layer 9 Light Guide Plate 10 Light Source 11 Light Scattering Layer 121 Light Scattering Material 122 Light Scattering Material 123 Light Scattering Material 13 Light Permeable layer 14 support

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[Procedure amendment]

[Submission date] September 8, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

[Correction content]

Finally, when the resin film 1 is dried to vaporize the poor solvent 4 (see FIG. 11), fine holes 7 remain after the poor solvent 4 flies away, and a large number of non-spherical and continuous fine particles are formed. The resin coating 8 has pores (see FIG. 7).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

When the poor solvent 4 is vaporized by further drying (see FIG. 6), fine pores 7 remain after the poor solvent 4 flies off, and the resin coating has a large number of non-spherical and continuous fine pores. 8 (see FIG. 7).

Claims (3)

[Claims] 1. A resin solution dissolved in a good solvent is applied or printed on a substrate to form a resin film, and the resin film is a poor solvent having a boiling point higher than that of the good solvent before the good solvent in the resin film is completely dried. A light-scattering material in which a good solvent and a poor solvent are vaporized in that order to form a non-spherical and continuous resin film having a large number of fine pores formed on the substrate A method for producing a light-scattering material, comprising: 2. A resin solution dissolved in a good solvent is applied or printed on a substrate to form a resin film, and the resin film is equal to or better than the good solvent before the good solvent in the resin film is completely dried. The poor solvent is vaporized by exposing it to a poor solvent with a low boiling point and an excess amount relative to the good solvent, and then drying the resin film to form a non-spherical and continuous resin film with many fine pores on the substrate. A method for producing a light-scattering material, comprising obtaining the formed light-scattering material. 3. A resin solution dissolved in a mixed solution of a good solvent and a poor solvent having a boiling point higher than that of the good solvent is applied or printed on a substrate to form a resin film, and the resin film is dried. A method for producing a light-scattering material, which comprises vaporizing a good solvent and a poor solvent in this order to obtain a light-scattering material having a non-spherical resin film having a large number of continuous fine pores formed on a substrate.