JP2002113718A - Method for treating light guide plate - Google Patents

Abstract

(57) [Problem] To provide a processing method for recycling a light guide plate used for a liquid crystal display device or the like at low cost and easily. SOLUTION: This is a method for treating a light guide plate 1 comprising a plate 2 having a surface provided with a pattern 3, wherein the light guide plate 1 is immersed in a treatment liquid to remove the pattern 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for recycling a light guide plate of a liquid crystal display device used for, for example, an information display device or a video display device.

[0002]

2. Description of the Related Art In recent years, the adverse effects of industrial activities on the natural environment have surfaced and the like, and environmental awareness has increased, and industrial activities that are more environmentally friendly have been demanded. Under such circumstances, the amount of general waste, industrial waste, and the like is increasing, and there is a concern that the remaining years of landfills for these wastes are concerned. Therefore, it is desired that a recycling method for industrial waste discharged from factories, such as used home electric appliances and information devices, be realized at an early stage.

Conventionally, used home electric appliances and information devices have been collected as wastes in processing facilities by local governments and the like, crushed collectively, and landfilled as they are. Or collected and crushed by a processor,
After some recyclable metals such as gold, iron, copper, and aluminum have been sorted and recovered, most of the remaining plastic crushed pieces have been landfilled. Recently, some intermediate processing companies have been able to improve the metal recovery rate by manually dismantling wastes such as home appliances and information devices. For this reason, recycling of metals has been considerably advanced. However, at present, most of the plastics and the like that occupy most of the wastes are landfilled, and recycling has hardly progressed.

[0004] In recent years, liquid crystal display devices have been recently developed because of their features of miniaturization, weight reduction, and power saving.
Its production is increasing rapidly, and it is being used for a wide range of home appliances and information devices. In the future, it is expected that the amount of used liquid crystal display devices will rapidly increase along with the increase in the production amount of the liquid crystal display devices. Therefore, with respect to the liquid crystal display device, it is desired that a lower cost and environmentally friendly recycling method be developed early.

At present, as a method of recycling used liquid crystal display devices, in order to increase a recycling rate, liquid crystal panels, plastics, metals, circuit boards, and lamps are disassembled and sorted into five parts, each of which is suitable. It has been proposed to carry out a recycling process. Some of plastics are recycled in blast furnaces as a substitute for coal.

[0006] However, the personal computer industry has announced that the recycling is thermal recycling and will not be treated as recycling. As can be seen from the above announcement, from the viewpoint of realizing a recycling-based society, there is an aspect that the recycling is not always desirable. Further, according to the above-mentioned recycling, since plastic is used as a fuel, the plastic is burned, and there is a problem such as generation of CO _{2 which has} a bad influence on the environment. Further, in order to use the blast furnace in a blast furnace, it is necessary to perform a pretreatment such as crushing and granulating the above-mentioned plastic, so that the processing cost is increased, and the discharger side (consumers, manufacturers of liquid crystal display devices, etc.) There is also a problem that the burden of ()) increases.

At present, a liquid crystal display device generally uses a light guide plate as shown in FIGS. 1 to 3 for diffusing light from a backlight or a sidelight. The light guide plate has an acrylic plate 2 as shown in FIG.
Adhesive 3a and fine powder silica 3b on one side of
The dot pattern 3 is formed by a mixture of an acrylic adhesive 3a and a fine powder silica 3b on one side of a wedge-shaped acrylic plate 12, as shown in FIG. By forming the light guide plate 11 and the dot pattern not formed on the wedge-shaped acrylic plate 22 as shown in FIG. 3, a reflective sheet is arranged on one surface of the acrylic plate 22, or unevenness is provided. Light guide plate 21 having dot pattern function
There is. Further, the light guide plates 11 and 21 shown in FIGS.
Is generally called a wedge-shaped light guide plate because of its cross-sectional shape. In general, as the wedge-type light guide plate, a liquid crystal display device in which a dot pattern is not formed as shown in FIG. 3 is often used, but a dot pattern 3 is formed as shown in FIG. Things are also used.

The light guide plate occupies a considerable weight in a liquid crystal display device. Therefore, if the light guide plate can be recycled, the recycling of the liquid crystal display device will be remarkably advanced. Also,
Since the light guide plate is generally formed of an acrylic plate, recycling of the acrylic plate, that is, acrylic resin is an important factor for recycling the light guide plate.

Regarding the acrylic resin, one recycling company recycles the acrylic resin from which impurities discharged from the factory are removed as acrylic pellets by directly crushing and granulating the acrylic resin. According to the recycling, since the acrylic resin containing no impurities is used, the impurities do not mix into the acrylic pellets. Therefore, the acrylic pellets can be recycled as high-quality products. According to the above-mentioned recycling, in the case of the light guide plate 21 having no dot pattern as shown in FIG. 3, even if used as it is, it can be recycled as acrylic pellets.

[0010]

However, in the above-mentioned recycling, if the light guide plates 1 and 11 on which the dot patterns 3 as shown in FIGS. The fine silica powder 3b is mixed as an impurity into the acrylic pellets. Acrylic pellets mixed with the finely powdered silica 3b have a problem that transparency, which is a feature of the acrylic resin, is impaired, and thus the commercial value is greatly reduced.

[0011] In addition, a certain overseas acrylic resin manufacturer performs a process of once returning the (meth) acrylic resin scraps and the like discharged from the factory to methyl methacrylate monomer by a dry distillation method, and converts the obtained methyl methacrylate monomer. By polymerizing again, a (meth) acrylic resin is recycled.

[0012] However, in the above-mentioned recycling, there is a problem in that the processing cost for returning the (meth) acrylic resin to the methyl methacrylate monomer is high, and the economic effect is small.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a processing method for recycling a light guide plate used in a liquid crystal display device at low cost and easily. is there.

[0014]

In order to solve the above-mentioned problems, a method for treating a light guide plate according to the present invention is a method for treating a light guide plate comprising a plate having a surface provided with a predetermined pattern,
The pattern is removed by immersing the light guide plate in a treatment liquid.

According to the above configuration, the pattern is removed by treating the light guide plate with the treatment liquid, so that only the plate containing no impurities can be taken out. Thereby, the plate can be easily recycled. In addition, the above treatment is only immersion of the light guide plate in the treatment liquid,
It can be implemented at low cost.

[0016] In the method for treating a light guide plate of the present invention, in addition to the above constitution, the pattern is formed of a (meth) acrylic resin, and the treatment liquid is formed of acetone, methyl ethyl ketone, benzene, xylene or ethyl acetate. A liquid containing at least one compound selected from the group consisting of:

According to the above arrangement, since the processing liquid dissolves the pattern, the pattern can be easily removed and only the plate can be taken out.

The method for treating a light guide plate of the present invention is characterized in that, in addition to the above configuration, the plate is an extruded or cast (meth) acrylic plate.

According to the above configuration, since the (meth) acrylic plate is generally made of a (meth) acrylic resin having a relatively high molecular weight, the (meth) acrylic resin having a relatively low molecular weight constituting the pattern is formed. The dissolution rate in the processing solution is much lower than that of the acrylic resin. Therefore, the pattern can be removed from the (meth) acryl plate by treating the light guide plate with the treatment liquid.

Further, by treating for a treatment time within a certain range, it is possible to remove only the pattern without dissolving the (meth) acryl plate and to make the surface of the plate the same as before forming the pattern. Mirror surface state.

The method for treating a light guide plate of the present invention is characterized in that, in addition to the above configuration, the plate from which the pattern has been removed is crushed and granulated.

According to the above configuration, since the plate from which the pattern has been removed is used, no impurities are mixed.
Therefore, the above-mentioned processing makes it possible to recycle the plate as high-quality pellets.

The method for treating a light guide plate of the present invention is characterized in that, in addition to the above configuration, the plate from which the pattern has been removed is monomerized.

According to the above configuration, since the plate from which the pattern is removed is used, no impurities are mixed.
Therefore, by the above-mentioned processing, the above-mentioned board can be recycled as a high quality monomer at low cost.

The method for treating a light guide plate of the present invention is characterized in that, in addition to the above constitution, the monomer is formed by a dry distillation method or an extrusion method.

According to the above configuration, since the dry distillation method or the extrusion method is employed, the monomer can be easily formed.

The method of processing a light guide plate according to the present invention is characterized in that, in addition to the above structure, a light guide plate is formed again by applying a new pattern to the plate from which the pattern has been removed.

According to the above configuration, a light guide plate can be formed again by applying a new pattern on the plate. That is, the plate can be recycled as a light guide plate.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a light guide plate 1 of one form suitable for processing using the processing method according to the present invention is a (meth) acryl plate (hereinafter simply referred to as an acrylic plate) as a plate. 2 is printed with a mixture of an acrylic adhesive (hereinafter simply referred to as an acrylic adhesive) 3a made of a (meth) acrylic resin having a relatively small molecular weight and a fine silica powder 3b. This is a configuration in which a kind of dot pattern 3 is formed. The acrylic plate 2 is produced by extrusion molding or casting molding of, for example, polymethyl methacrylate having a relatively large molecular weight. The light guide plate 1 is mainly used for a liquid crystal display device requiring high luminance or a large liquid crystal display device of 15 inches or more. The light guide plate 1 occupies about 40% of the weight of the liquid crystal display device. Hereinafter, the light guide plate 1 may be referred to as an extrusion molded product.

As shown in FIG. 2, a light guide plate 11 of another form suitable for processing by using the processing method according to the present invention has an acrylic adhesive 3a formed on an acrylic plate 12 having a wedge-shaped cross section. The dot pattern 3 is formed by printing a mixture of the silica powder 3b and the fine silica powder 3b. The acrylic plate 12 is made by injection molding. Injection molding requires fluidity of the material. For this reason, as the material of the acrylic plate 12, for example, polymethyl methacrylate having a relatively small molecular weight capable of ensuring fluidity is used. The light guide plate 11 is widely used in a liquid crystal display device in which weight is regarded as important, for example, a liquid crystal display device for a notebook computer or a portable information terminal.
The light guide plate 11 occupies about 20% of the weight of the liquid crystal display device, and occupies the second largest weight after the liquid crystal panel. Hereinafter, the light guide plate 11 may be referred to as an injection molded product.

The light guide plates 1 and 11 may be made of a plate made of a material other than an acrylic plate, for example, a plate made of a cycloolefin polymer.

Here, a processing method for recycling the light guide plates 1 and 11 on which the dot patterns 3 are formed will be described. As shown in FIG. 4, the light guide plates 1 and 11 are immersed in a processing tank (processing apparatus) 4 containing a processing liquid 5, so that an acrylic adhesive 3 a formed on the acrylic plates 2 and 12 and The dot pattern 3 made of the fine silica powder 3b is peeled or dissolved and removed. In order to promote the removal of the dot pattern 3, ultrasonic waves are applied to the processing tank 4 using a vibrator 6, or the light guide plate 1
・ 11 may be swung. The acrylic plates 2 and 12 from which the dot patterns 3 have been removed are crushed and granulated to be recycled as high-purity acrylic pellets.
Alternatively, the acrylic plate 2 from which the dot pattern 3 has been removed
High purity (high quality) by monomerizing 12
Recycled as a methyl methacrylate monomer. Alternatively, a new dot pattern is printed on the acrylic plates 2 and 12 to be recycled as a light guide plate.

The treatment liquid 5 includes a dot pattern 3
Any liquid can be used as long as it is capable of removing, and is not particularly limited. When the dot pattern 3 is made of a (meth) acrylic resin, the processing liquid 5 may be acetone, benzene, xylene, methyl ethyl ketone (ME
K), ethyl acetate, tetrahydrofuran, toluene, phenol, glacial acetic acid, methylene dichloride, ethylene dichloride,
Compounds that dissolve (meth) acrylic resins such as trichloromethane and trichloroethylene are exemplified. The above compounds may be used alone or in a mixture of two or more, or as an aqueous solution thereof.
Acetone, benzene, xylene, methyl ethyl ketone (MEK), ethyl acetate and aqueous acetone are more preferred.

The above-described processing can be performed not only on a light guide plate taken out of a used liquid crystal display device or the like, but also on a defective light guide plate caused by a defective dot pattern formation in a manufacturing process of the light guide plate. it can. In addition, the above-described processing can be performed on a defective product generated in a process other than the above in a manufacturing process of a liquid crystal display device or the like after the light guide plate is taken out.

After the light guide plates 1 and 11 are crushed, the dot pattern 3 may be removed using the processing liquid 5. However, in this case, the fine powder silica 3b in the removed dot pattern 3 is
12 may be redeposited. Therefore, it is preferable to remove the dot pattern 3 before crushing the light guide plates 1 and 11.

Here, as an example, a method of crushing, granulating, and monomerizing an acrylic plate will be described.

The crushing of the acrylic plate can be performed, for example, using a commercially available single-shaft crusher. Generally, as shown in FIG. 5, the configuration of the single-shaft crusher is such that an arrow A is placed in a crushing chamber 32 surrounded by an iron plate 31 on four sides and a screen 36 on the lower surface.
, And a rotating blade 34 attached to the rotor 33. A fixed blade 35 is attached to two opposing portions of the iron plate 31 so as to mesh with the rotating blade 34. Further, below the crushing chamber 32, a discharge port 38 surrounded by an iron plate 37 on all sides is provided. The rotating blade 34 and the fixed blade 35 are positioned at an interval suitable for crushing the material to be crushed (here, an acrylic plate), for example, 0.3 mm to 2 mm, and positioned. . The rotation speed of the rotor 33 and the rotary blade 34 often rotates at a relatively high speed of about 600 rpm. However, when the acrylic plates 2 and 12 are crushed, this rotation speed does not cause any problem.

While the rotor 33 and the rotary blade 34 are rotating, the acrylic plates 2 and 12 are moved in the direction of arrow B in the crushing chamber 3.
2, the rotating blade 34 and the fixed blade 35
The acrylic plates 2 and 12 are sheared and crushed. Screen 36
Is provided with a number of holes large enough to obtain crushed pieces of acrylic plates 2 and 12 suitable for later recycling, and the crushed acrylic plates 2 and 12 are sized so that they can pass through the holes. The crushed pieces 2 and 12 pass through the screen 36 and are discharged from the discharge port 38. The crushed pieces of the acrylic plates 2 and 12 larger than the holes provided in the screen 36 are scraped up by the rotor 33 and the rotary blade 34 to have a size capable of passing through the holes provided in the screen 36. The crushing is repeated until it becomes.

The granulation is performed, for example, by using a commercially available extruder.
It can be performed by a granulating device combining a stretching machine and a cutter.

Generally, as shown in FIG. 6, the structure of the granulating apparatus comprises an extruder 42, a cooling water tank 46, and a cutter 48. The extruder 42 includes a hopper 41 for charging, a heater 43 for melting the plastic, and an extrusion plate 44 having a plurality of holes for extruding the molten plastic into a string having a predetermined outer diameter. . The cooling water tank 46 is provided for cooling and solidifying the molten plastic while stretching it. And cutter 4
Reference numeral 8 is provided for cutting the string-shaped plastic solidified in the cooling water tank 46 into a predetermined length. Further, in the extruder 42, there is a rod-shaped screw (not shown) provided with a spiral groove, and by rotating this screw, the molten plastic is extruded.

First, the crushed pieces 2a and 12a of the acrylic plate are put into the hopper 41 in the direction of arrow C. The input acrylic plate crushed pieces 2 a and 12 a are extruded in the direction of the extruded plate 44 by a rod-shaped screw provided in the extruder 42, and are heated and melted by the heater 43.
Usually, the temperature of the heater 43 is set to about 240 ° C. At this time, the crushed pieces 2a and 12a of the acrylic plate become approximately 280 ° C. due to the shearing force when they are extruded by the screw, and the fluidity increases. Then, a plurality of holes provided in the extruded plate 44 form a string-like molten acrylic resin 2b / 1.
2b is extruded. The extruded string-like molten acrylic resin 2b, 12b is guided into the cooling water tank 46 by the guide roller 45. Molten acrylic resin 2b ・ 12b
Is drawn by the stretching roller 47 and the guide roller 45 in the direction of the cutter 48 (in the direction of arrow D), and has a predetermined outer shape while being cooled. Then, it is cut into a desired length by the cutter 48 and granulated into the recycled acrylic pellets 2c and 12c. Usually, the size of the recycled acrylic pellets 2c and 12c is granulated to a diameter of about 2 × 3 mm.

As a method of monomerizing the acrylic plate,
There are a carbonization method and an extrusion method.

In the dry distillation method, a (meth) acrylic resin is heated to a high temperature of about 450 ° C. in a nitrogen gas atmosphere to decompose and gasify, and the gas is cooled to obtain a liquid methyl methacrylate monomer. is there. This method has a problem in that the amount of electric power used for heating is large, thereby increasing the processing cost. In addition, if impurities are mixed in the (meth) acrylic resin as a raw material, a process such as fractionation in a post-treatment process becomes complicated. Therefore, it is desirable to use a highly pure (meth) acrylic resin as a raw material. In particular, impurities (solids) that are not decomposed in the above processing, such as the fine powder silica 3b used for the dot patterns 3 of the light guide plates 1 and 11, remain in the apparatus for monomerization. Therefore, it is necessary to stop the operation of the apparatus and remove the impurities. Therefore, it is desirable to remove impurities and the like in advance.

As an extrusion method, a method of monomerization using a twin screw extruder is promising as an inexpensive method. This method uses a monomer reduction twin screw extruder,
The (meth) acrylic resin is melted and thermally decomposed, and the monomer is recovered by a condenser.

This method has a lower processing cost than the dry distillation method. However, if impurities are mixed in the (meth) acrylic resin, which is a raw material, a process such as fractionation in a post-treatment process becomes complicated. Therefore, it is desirable to use a highly pure (meth) acrylic resin as a raw material. In particular, impurities (solids) such as the fine powder silica 3b used in the dot patterns 3 of the light guide plates 1 and 11 remain in the twin-screw extruder during this treatment.
For this reason, it is necessary to stop the operation of the twin-screw extruder to remove the impurities. Therefore, the impurities and the like,
It is desirable to remove them in advance.

Hereinafter, an example of a processing method for recycling the light guide plate through an experiment will be described more specifically. As shown in FIG. 4, the light guide plate 1 was immersed in a commercially available processing tank 4 containing acetone as the processing liquid 5. The processing time of the light guide plate 1 was changed while the vibrator 6 was operated and ultrasonic waves were applied, and the state change of the acrylic plate 2 and the dot pattern 3 in the light guide plate 1 was examined.

Table 1 shows the results when the extruded product (FIG. 1) as the light guide plate 1 was treated.

[0049]

[Table 1]

As shown in Table 1, the light guide plate 1 was immersed in acetone (100% by weight) for 5 seconds or more in a state where ultrasonic waves were applied, so that the dot pattern 3 was completely peeled off from the acrylic plate 2. It turns out that you can.
It has been found that the dot pattern 3 can be completely peeled and removed in 10 seconds or more with an acetone 90% by weight aqueous solution. Further, it was found that the dot pattern 3 can be completely peeled and removed in one minute or more with an 80% by weight aqueous solution of acetone. Therefore, it was found that by performing the above-described processing, only the acrylic plate 2 could be taken out. The acrylic plate 2 can be recycled as acrylic pellets by crushing and granulating.

Further, by referring to the weight loss of the light guide plate 1 in Table 1, it was found that the acrylic plate 2 began to dissolve in acetone (100% by weight) when the treatment time exceeded 2 minutes. In addition, it was found that the acrylic plate 2 began to be dissolved when the treatment time exceeded 6 minutes in an acetone 80% by weight aqueous solution. From the above, the acrylic adhesive 3
a and the acrylic plate 2 differ greatly in the dissolution rate in the treatment liquid 5, and it has been found that the dissolution rate of the acrylic adhesive 3a is considerably higher. It is considered that this difference in dissolution rate is mainly caused by a difference in molecular weight between the acrylic adhesive 3a and the acrylic resin that is a component of the acrylic plate 2. That is, it is considered that the acrylic adhesive 3a whose main component is a (meth) acrylic resin having a relatively low molecular weight has a higher dissolution rate in acetone than the acrylic plate 2 having a relatively high molecular weight. Therefore, the acrylic adhesive 3a
Is dissolved in the processing liquid 5 first, so that the dot pattern 3
Can be peeled off.

In the light guide plate 1, acetone (100
(% By weight), it was found that the dot pattern 3 can be completely peeled off without dissolving the acrylic plate 2 in a range of 5 seconds or more to less than 2 minutes. In addition, it has been found that the dot pattern 3 can be removed without dissolving the acrylic plate 2 in the range of 1 minute or more to less than 6 minutes with an acetone 80% by weight aqueous solution. When the treatment was performed for a time within the above range, the surface of the acrylic plate 2 had a mirror surface state equivalent to that before the dot pattern 3 was printed. Therefore, when the light guide plate 1 is processed under the above conditions, the acrylic plate 2 can be recycled as a light guide plate by printing a new dot pattern without performing further processing.

Next, Table 2 shows the results obtained when the injection molded product (FIG. 2) as the light guide plate 11 was treated.

[0054]

[Table 2]

As shown in Table 2, it was found that in this case, dissolution of the acrylic plate 12 started with the dot pattern 3 not completely peeled off. That is, although the dissolution rate of the acrylic plate 12 in the treatment liquid 5 is slightly lower than that of the acrylic adhesive 3a, it is considered that there is no significant difference between the dissolution rates of the two. Further, it can be seen that the time required for the dot pattern 3 to be completely peeled off is long. This is probably because the acrylic plate 12 was dissolved at the same time, and the dissolution rate of the acrylic adhesive 3a was reduced due to the change in the concentration of the treatment liquid 5. Although different from the case of the extruded product in the above points, the dot pattern 3 can be completely peeled and removed from the acrylic plate 12. In this case, the dissolution of the acrylic plate 12 starts before the dot pattern 3 is completely peeled and removed.
The surface of the acrylic plate 12 became cloudy and could not be mirror-finished. Therefore, the acrylic plate 12 cannot be recycled as a light guide plate as it is. However, the acrylic plate 12 is crushed,
By granulating, it can be recycled as acrylic pellets.

Then, benzene, xylene, methyl ethyl ketone (ME
K), an experiment was performed using ethyl acetate as the treatment liquid 5. As shown in FIG. 4, the light guide plate 1 was immersed in a commercially available treatment tank 4 containing the treatment liquid 5. The processing time of the light guide plate 1 was changed while the processing tank 4 was rocked, and the state change of the acrylic plate 2 and the dot pattern 3 in the light guide plate 1 was examined. Table 3 shows the results.

[0057]

[Table 3]

As shown in Table 3, when the dot pattern 3 was peeled off using xylene as the processing liquid 5, the processing time was long, but the dot pattern 3 was peeled off with all the processing liquids tested. It has been found that removal is possible. Therefore, it was found that even when the above compound was used, only the acrylic plate 2 could be taken out.

After the dot pattern 3 is peeled and removed by the treatment liquid 5, the acrylic plate 2 is made of a material such that the peeled dot pattern 3 (acrylic adhesive 3a and fine powder silica 3b) is prevented from reattaching. Washing with clean water or a solvent is more preferable. In order to use the treatment liquid 5 repeatedly, it is more preferable that the treatment liquid 5 used for peeling and removing the dot pattern 3 is circulated and filtered to remove the fine silica powder 3b and to clean it.

In order to reduce the amount of the processing liquid 5, the processing time of the light guide plate is preferably as short as possible within a range in which the dot pattern 3 is completely removed. If the type of the acrylic adhesive 3a used for the dot pattern 3 is different, the time required to peel and remove the dot pattern 3 changes. It is desirable to confirm.

Here, the dot pattern 3
An evaluation was made as to whether the acrylic plates 2 and 12 from which the was removed could be recycled.

First, as a first evaluation method, a sample (acryl plate) is put in a glass container, heated to a temperature of 280 ° C. or more in a nitrogen gas atmosphere, melted, and then cooled to a thickness of 5 mm. Boards were prepared and evaluated for recycling by evaluating the boards. The above evaluation method is a simple alternative to the method of evaluating a plate formed by injection molding. A sample having a good dot pattern 3 peeling state (dot pattern peeling state of ○ (completely peeling) in Tables 1 to 3) was used as a sample,
The evaluation was performed by the above evaluation method. Although the above-mentioned plate was made by a simple method, although air bubbles were mixed in, all the plates made from each sample were colorless, high in transparency and high quality acrylic plate. Therefore, it was found that the sample could be recycled.

As a second evaluation method, a sample is crushed to a size of 10 mm or less using a commercially available uniaxial crusher, and these crushed pieces are crushed at a set temperature of about 240 ° C. using a commercially available extruder. Granules having a diameter of about 2 × 3 mm were formed into regenerated pellets, and the regenerated pellets were subjected to injection molding using a commercially available molding machine to prepare acrylic beads having a diameter of 10 mm. The acrylic beads were evaluated to evaluate recycling. As a sample,
In Table 2, the dot pattern 3 in which the peeling state was good (in the table, the dot pattern peeling state was ○ (these were the surface of the acrylic plate 12 being dissolved and becoming cloudy) were used) and the above evaluation method was used. Was evaluated. The acrylic beads were of high commercial value, with no difference in color appearance, transparency, and gloss compared to acrylic beads prepared by injection molding of virgin pellets. Therefore, it was found that the sample could be recycled as regenerated pellets.

As a third evaluation method, the sample is heated to 450 ° C. or more in a nitrogen gas atmosphere, decomposed, and the generated gas is cooled to collect the methyl methacrylate monomer, and the monomer is evaluated. An evaluation of recycling was performed. As a sample, a sample in which the dot pattern 3 had a good peeling state (in Tables 1 to 3 the dot pattern had a good peeling state) was evaluated by the above evaluation method. No foreign matter was mixed in any of the monomers recovered from each sample, and high-quality monomers were obtained. When the above monomer was polymerized, a high quality acrylic resin having no color and high transparency was obtained. Therefore, it was found that the sample could be recycled as a methyl methacrylate monomer.

As described above, according to the method for treating a light guide plate of the present invention, no special treatment liquid or device is required, so that the light guide plate can be processed and recycled at low cost and easily.

[0066]

As described above, the method for treating a light guide plate according to the present invention is a method for treating a light guide plate comprising a plate having a surface provided with a predetermined pattern, wherein the light guide plate is immersed in a treatment liquid. Then, the above-described pattern is removed.

According to the above configuration, only a plate containing no impurities can be taken out. Thereby, the plate is
This has the effect of being easily recyclable at low cost.

In the method for treating a light guide plate of the present invention, in addition to the above constitution, the pattern is formed of a (meth) acrylic resin, and the treatment liquid is prepared from acetone, methyl ethyl ketone, benzene, xylene and ethyl acetate. A liquid containing at least one compound selected from the group consisting of:

According to the above configuration, since the processing liquid dissolves the pattern, the pattern can be easily removed and only the plate can be taken out.

The method for treating a light guide plate of the present invention has a structure in which, in addition to the above structure, the plate is a (meth) acrylic plate formed by extrusion molding or casting.

According to the above arrangement, by treating the light guide plate with the treatment liquid, there is an effect that the pattern can be removed from the (meth) acryl plate.

Further, there is an effect that the surface of the plate can be made into the same mirror surface state as before the pattern is formed.

The method for treating a light guide plate of the present invention has a structure in which, in addition to the above-described structure, the plate from which the pattern has been removed is crushed and granulated.

According to the above configuration, by the above processing,
There is an effect that the plate can be recycled as pellets.

The method for treating a light guide plate of the present invention has a structure in which, in addition to the above structure, the plate from which the pattern has been removed is monomerized.

According to the above configuration, by the above processing,
This has the effect that the plate can be recycled at a low cost and with high quality, for example, as methyl methacrylate monomer.

The method for treating a light guide plate of the present invention has a structure in which, in addition to the above structure, a monomer is formed by a dry distillation method or an extrusion method.

According to the above-described structure, since the dry distillation method or the extrusion method is employed, there is an effect that the monomer can be easily formed.

The method for processing a light guide plate of the present invention has a structure in which a light guide plate is formed again by applying a new pattern to the plate from which the pattern has been removed, in addition to the above structure.

According to the above configuration, the plate can be recycled as a light guide plate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing an embodiment of a light guide plate processed using the processing method according to the present invention.

FIG. 2 is a cross-sectional view of a main part showing another embodiment of a light guide plate processed using the processing method according to the present invention.

FIG. 3 is a sectional view of a main part showing another embodiment of the light guide plate.

FIG. 4 is a schematic sectional view of a processing apparatus used in the processing method of the present invention.

FIG. 5 is a schematic sectional view of a uniaxial crusher for crushing an acrylic plate.

FIG. 6 is a schematic sectional view of an apparatus for granulating acrylic pellets.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide plate 2 (meth) acryl plate (plate) 2a fragment of acrylic plate 2b molten acrylic resin 2c recycled acrylic pellet 3 dot pattern (pattern) 3a acrylic adhesive 3b fine powder silica 4 treatment tank 5 treatment liquid 6 vibrator 11 Light guide plate 12 (meta) acrylic plate (plate) 12a fragment of acrylic plate 12b molten acrylic resin 12c recycled acrylic pellet 34 rotating blade 35 fixed blade 36 screen 42 extruder 46 cooling water tank 48 cutter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 31:02 G02F 1/1335 530 F-term (Reference) 2H091 FA23Z FB02 FC17 LA12 LA30 4F301 AA20 BD11 BD29 BD31 BD36 BD42 BF06 BF12 BF16 BF20 BF32 CA09 CA25 CA41 CA51 CA68 CA72 4J038 RA01 RA02

Claims (7)

[Claims] 1. A method for processing a light guide plate comprising a plate having a predetermined pattern formed on a surface thereof, wherein the light guide plate is immersed in a processing solution to remove the pattern. Processing method. 2. The pattern is formed of a (meth) acrylic resin, and the treatment liquid is a liquid containing at least one compound selected from the group consisting of acetone, methyl ethyl ketone, benzene, xylene, and ethyl acetate. The method for treating a light guide plate according to claim 1, wherein: 3. The method for processing a light guide plate according to claim 2, wherein said plate is an extruded or cast molded (meth) acryl plate. 4. The method for processing a light guide plate according to claim 1, wherein the plate from which the pattern has been removed is crushed and granulated. 5. The method for processing a light guide plate according to claim 1, wherein the plate from which the pattern has been removed is monomerized. 6. The method for treating a light guide plate according to claim 5, wherein the monomer is formed by a dry distillation method or an extrusion method. 7. The light guide plate processing method according to claim 1, wherein a light guide plate is formed again by applying a new pattern on the plate from which the pattern has been removed.