KR20070074630A - Resin extruded plate for optical use and method for manufacturing same - Google Patents

Abstract

Disclosed is a resin extruded plate for light guide plates which is suitable for displays used in office automation equipment such as personal computers and word processors, various monitors for displaying image signals such as panel monitors and television monitors as well as displays or advertising displays used in illuminating devices for indoor or outdoor spaces. Specifically disclosed is a resin extruded plate which is characterized in that it comprises surface protection films bonded to both sides of a plate having a thickness of 2-15 mm, there is no cutting dust having a size of 0.1 mm^2 or more on the films, and there is no recess and/or dent having a size of 0.1 mm^2 or more in the plate surface. Also disclosed is a method for manufacturing such a resin extruded plate.

Description

Optical resin extruded plate and manufacturing method thereof {RESIN EXTRUDED PLATE FOR OPTICAL USE AND METHOD FOR MANUFACTURING SAME}

INDUSTRIAL APPLICABILITY The present invention is a liquid crystal display used as a display device such as a laptop or desktop personal computer, a portable information terminal, a game machine, a workstation, an image monitor, or a television. It relates to a resin extruded plate suitable for. Moreover, this invention relates to the manufacturing method of the resin extruded board suitable for the light-guide plate which is suitable for manufacturing the backlight apparatus which does not impair the brightness | luminance or image quality of a liquid crystal display.

CRTs, so-called CRTs, have long been used as information and image display devices. In recent years, in response to requests for thinning and miniaturization of display devices, liquid crystal displays tend to replace CRTs. In the liquid crystal display, since the liquid crystal unit itself does not have a function of emitting light, a so-called backlight device is generally used which makes the display easy to see by illuminating the liquid crystal unit from the back side.

In the method of this backlight device, 1) a "diffusion plate" having a function of scattering light is sandwiched between the light source and the liquid crystal unit, the so-called direct type, and 2) the light source is attached to the edge of the light guide plate and the reflecting plate on the back of the light guide plate. Two types of edge lights, which emit light in the surface direction by using, are commonly used. Currently, the edge light method is the mainstream. In particular, in recent years, the demand for higher brightness, larger size, and thinner display device has been increased, and development has been progressed under the product concept of being brighter, larger, and thinner. In particular, development of a high-brightness backlight device in the edge light method is strongly desired.

For this reason, with respect to the light guide plate used in the backlight device, there is a strong demand for the light guide plate for efficiently emitting incident light incident from the light source lamp disposed on the side surface to the exit surface.

In response to such a demand, a plurality of technical disclosures have been made so far with respect to the method of increasing the brightness using a light guide plate. For example, Japanese Patent Laid-Open No. 39-1194 discloses a method of obtaining a uniform light emitting surface by dispersing and mixing light diffusing particles in a light guide plate, and Japanese Patent Laid-Open No. 4-145485 discloses a light guide. Although the method of making high brightness etc. by using the light-scattering plastic material containing microparticles | fine-particles with which refractive index differs in a sieve is disclosed, a process is complicated.

However, in addition to these complicated techniques using methacryl resin containing fine particles, the reality has not been reached in a level that can sufficiently cope with the demands for the increase in size and thickness of display devices in luminance and luminance unevenness.

In addition, since the resin extruded plate for light guide plates is generally cut into saws in order to have a predetermined width and length after adhering the surface protection film to the front and back so that the surface of the plate is not damaged, the cutting powder is easily attached to the surface protection film. . The produced resin extruded plate is loaded on a pallet or the like and stored and transported. As a result, the cutting powder adhering to the surface protection film is pressed by the weight of the overlapping plate, which causes a recess in the surface of the plate, or in a significant case, causes the surface protection film to be torn and scratches on the surface of the plate. Particularly, in the resin extruded plate exported overseas, the cutting powder of the plate tends to damage the surface protection film due to the shaking of the ship to be transported, and also the recesses and the damage on the surface of the plate are likely to occur.

When recesses or scratches due to the cutting powder are formed on the surface of the light guide plate, light incident from the light source lamp is scattered at positions of recesses or scratches on the surface, so-called bright spots, thereby lowering the luminance. Moreover, when there are many recesses and scratches, it becomes a fault when it sees on a liquid crystal screen.

As a cutting method of the resin extruded plate to prevent the first cutting powder from occurring, 1) sha cutting machine for pressing and cutting the knife from one side or both sides of the plate, 2) cutting device with laser beam, 3) cutting device with water jet Etc. can be mentioned. However, they are not only large and expensive devices, but 1) sha cutters are easy to blunt knives, the maintenance cost is large due to the exchange of knives, and 2) laser cutters are not clean, especially in thick plates, One resin mist is easy to adhere to the plate, the maintenance cost for the replacement of the reflector is large, and 3) the water jet cutting machine has a problem that the cutting surface is not clean.

The method of cutting the resin plate with a saw is most suitable for stable production, but until now there has been no method for strictly removing the generated cutting powder. Even after cutting the resin plate, the cutting powder attached to the surface protection film is blown by the compressed air from the nozzle, and it is not only difficult to remove the fine 0.1 mm 2 cutting powder strictly, but also the blowing powder once blown is applied to the surface protection film. It may be attached. Even when a suction nozzle is provided and removed at the front and back of the plate, it is difficult to suck up fine cutting powder sufficiently, and if the suction is too strong, the plate itself is adsorbed and the stable production is inhibited.

Moreover, although the thickness of a protective film is thickened, for example, 90 micrometers or more so that even if a cutting powder adheres, in order that a recess or damage may not arise in the surface of a board | plate, there is also a difficult prevention.

Patent Document 1: Japanese Patent Publication No. 39-1194

Patent Document 2: Japanese Patent Application Laid-Open No. 4-145485

An object of the present invention is to provide a resin extruded plate with no cutting powder, which is suitable as a light guide plate of an edge light type backlight device having high brightness for a liquid crystal display.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, it discovered that high brightness | luminance of a backlight apparatus can be achieved by strictly removing the cutting powder on the surface protection film of a board, and came to complete this invention.

That is, in the present invention, the surface protective film is adhered to the front and back of the plate having a sheet thickness of 2 to 15 mm, there is no cutting powder having a size of 0.1 mm 2 or more on the film, and the concave portion having a size of 0.1 mm 2 or more on the surface of the plate, and / Or it relates to a resin extruded plate and a method for producing the same, characterized in that there is no scratch.

Effect of the Invention

The resin extruded plate of the present invention does not have bright spots derived from the adhesion of the cutting powder, and the luminous efficiency of light received from the light source lamp can be improved to the maximum.

1 shows an example of a cutting powder suction rotary brush in the present invention.

Figure 2 shows the thickness measurement point in the present invention.

3 illustrates an example of a bright point evaluation method in an edge light type liquid crystal light source device using the light guide plate of the present invention.

4 shows an example of a luminance evaluation method in an edge light type liquid crystal light source device using the light guide plate of the present invention.

5 shows an example of a production facility for a resin extruded plate according to the present invention.

Best Mode for Carrying Out the Invention

This invention is demonstrated concretely below.

The resin extrusion plate of this invention can be manufactured by melt-extruding raw material resin and making it into the shape of a board | plate. As raw material resin, methacryl resin (PMMA), polystyrene (PS), styrene / methyl methacrylate resin (MS), acrylonitrile / styrene resin (SAN), polycarbonate (PC), amorphous polyester, alicyclic It can be used as long as it is a transparent and melt-molded resin such as polyolefins (APO of Mitsui Seki Oil Chemical, Zeonex and Nihon Xeon, Zeonor of JSR, and ARTON of JSR). have. In addition, the raw material resin may be used alone, or may be mixed with additives such as a light diffusing agent, a fluorescent brightener, an ultraviolet absorber, an antioxidant, a plasticizer, a mold releasing agent, a dye, and a pigment within a range of not lowering the luminance. The plate may be produced by extrusion into a single layer, or may be laminated in two or more layers by a coextrusion method or a lamination method.

Among the raw material resins, methacryl resins, polycarbonates or alicyclic polyolefins are preferable as raw materials for the light guide plate from the viewpoint of transparency, and among them, methacryl resins have properties such as colorless transparency, light resistance, molding processability, mechanical strength and surface hardness. Especially preferably, it is used.

The methacryl resin which can be used especially preferable in this invention can be obtained by copolymerizing 70 weight% or more of methyl methacrylate and / or ethyl methacrylate, and less than 30 weight% of monomers copolymerizable with these, for example. have. Examples of the monomer having copolymerizability include meta methacrylates such as propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, tricyclodecyl methacrylate, phenyl methacrylate and benzyl methacrylate. Acrylate esters, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, tricyclodecyl acrylate, phenyl acrylate, benzyl acrylate, methacrylic acid, acrylic acid Although unsaturated acids, maleic anhydride, maleimide, etc. are mentioned, It is not limited to this. In addition, these monomers may be used independently or may be used in mixture of 2 or more types.

Resin used as a raw material of the resin extrusion board which concerns on this invention can also use what was obtained by the superposition | polymerization method of any, such as suspension polymerization method, emulsion polymerization method, cast polymerization method, continuous block polymerization method, and continuous solution polymerization method. In particular, resins produced by the suspension polymerization method and the continuous solution polymerization method, in particular, methacryl resins, have few impurities and are preferable as raw material resins of the light guide plate.

The suspension polymerization method of methacryl resin as an example of a raw material is demonstrated. First, the polymerization initiator and the chain transfer agent are uniformly dissolved in a monomer mixture containing methyl methacrylate and / or ethyl methacrylate and other copolymerizable monomers. It is obtained by suspending the homogeneous melt in a water medium in which a dispersion stabilizer is present, then maintaining the mixture at a predetermined polymerization temperature for a predetermined time to complete the polymerization, and filtering the resulting turbid polymer, washing with water and drying.

As a polymerization initiator used at the time of suspension polymerization, the radical polymerization initiator etc. which were well-known for the polymerization of a vinyl monomer are mentioned. For example, azobisisobutyronitrile, 2,2'- azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'- azobisisobutyrate, t-butylperoxy pivalate, t -Butyl peroxy-2-ethyl hexaate, cumylperoxy-2-ethylhexanoate, benzoyl peroxide, lauroyl peroxide, etc. are mentioned. The amount of these polymerization initiators used is usually preferably in the range of 0.01 to 2.0 parts by weight based on 100 parts by weight of the monomer or monomer mixture.

As a chain transfer agent used at the time of suspension polymerization, the well-known thing used for superposition | polymerization of methyl methacrylate may be used. For example, t-butyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, t-dodecyl mercaptan, etc. are mentioned. The use amount of these chain transfer agents is generally in the range of 0.01 to 2.0 parts by weight based on 100 parts by weight of the monomer or monomer mixture.

Although it does not specifically limit as a dispersion stabilizer used at the time of suspension superposition | polymerization, water-insoluble inorganic compounds, such as calcium phosphate, calcium carbonate, and aluminum hydroxide, a nonionic high molecular compound of polyvinyl alcohol, polyethylene oxide, a cellulose derivative, polyacrylic acid, Anionic polymer compounds, such as its salt, polymethacrylic acid and its salt, copolymer of methacrylic acid ester, methacrylic acid, and its salt, are mentioned. The use amount of these dispersion stabilizers is preferably in the range of 0.01 to 5.0 parts by weight based on 100 parts by weight of water.

Pure water, ion-exchange water, deionized water, etc. are mentioned as water used at the time of suspension polymerization. Although the usage-amount of water is not specifically limited, The range of 100-300 weight part is preferable with respect to 100 weight part of monomers or a monomer mixture.

Moreover, it is although it does not specifically limit as polymerization temperature of suspension polymerization, It is about 60-120 degreeC, and it is set as the temperature suitable for the polymerization initiator to be used. As a polymerization apparatus, it is common to use the polymerization container provided with the well-known stirring blade, for example, a stirrer with wings, such as a turbine blade, a feather blade, a propeller blade, a blue margin blade, and the said container is affixed with a baffle. to be.

Moreover, a light diffusing agent, a ultraviolet absorber, a fluorescent brightener, antioxidant, a plasticizer, a mold release agent, a dye, a pigment, etc. can also be suspended and polymerized as needed.

After completion | finish of suspension polymerization, spherical resin polymer (for example, spherical methacryl resin polymer) can be obtained by washing | cleaning, dehydration, and drying by a well-known method.

The average particle diameter of the spherical resin used as a raw material for the resin extruded plate according to the present invention is 0.2 to 0.5 mm, preferably 0.25 to 0.39 mm. If it is less than 0.2 mm, good plate | board thickness precision is not obtained, and it is difficult to stably manufacture the polymer which has an average particle diameter exceeding 0.5 mm.

In addition to the spherical resin by suspension polymerization method, resin used as a raw material of a resin extrusion plate in this invention supplies a spherical resin polymer to the extruder with a vent, and the temperature is 220-260 degreeC, and vent vacuum pressure 10-60 Torr. Columnar (pellet) resin obtained by extruding and water-cooling into a strand form from an extrusion die and cutting | disconnecting with a strand cutter, and the resin polymer of the molten state obtained by the well-known continuous solution polymerization method and the continuous block polymerization method from an extrusion die A columnar (pellet) resin obtained by extruding and water-cooling into a strand shape and cutting with a strand cutter can be used. Examples of the continuous solution polymerization method and the continuous bulk polymerization method include the following methods. As a solvent in the continuous solution polymerization method, a boiling point higher than that of the monomer of the raw material resin (for example, a monomer copolymerizable with the methyl methacrylate monomer and the methyl methacrylate monomer and the methyl methacrylate) in the bottom of the distillation column and the inside of the distillation column What has, specifically, aromatic compounds, such as toluene, xylene, ethylbenzene, diethylbenzene, aliphatic compounds, such as octane and decane, alicyclic compounds, such as decalin, esters, such as butyl acetate and pentyl acetate, 1,1 And halogen compounds such as 2,2-tetrachloroethane. In particular, alkylbenzene, and toluene, xylene, and ethylbenzene are preferable since it has a suitable boiling point, a small load also to degassing, and does not adversely affect superposition | polymerization. The amount of the solvent also varies depending on the boiling point of the solvent, but is preferably 30% by weight or less, more preferably 25% by weight or less, based on the weight of the entire mixture at the time of polymerization. If a solvent is not used at the time of polymerization, it will become block polymerization.

The polymerization initiator used in the continuous solution polymerization method or the continuous bulk polymerization method may be a polymerization initiator that decomposes to active at the polymerization temperature to generate radicals. For example, di-t-butyl peroxide, dicumyl peroxide, methylethyl ketone peroxide, di-t-butyl perphthalate, di-t-butyl perbenzoate, t-butyl peracetate, 2,5-dimethyl -2,5-di (t-butylperoxy) hexane, 1,1-bis (t-butylperoxy)-(3,3,5-trimethyl) cyclohexane, 1,1-bis (t-butylperoxy Oxy) cyclohexane, di-t-amyl peroxide, benzoyl peroxide, cumene hydroperoxide, lauryl peroxide, azobisisobutanol diacetate, 1,1'-azobiscyclohexanecarbonitrile, 2-phenylazo 2,4-dimethyl-4-methoxyvaleronitrile, 2-cyano-2,2-propyl azo formic acid, 2,2'- azobisisobutyronitrile, etc. are mentioned. The use amount of these polymerization initiators is preferably 0.001 to 0.03% by weight based on the weight of the entire reaction mixture.

In addition, mercaptans are mainly used as a molecular weight regulator used at this time. As mercaptans, for example, n-butyl mercaptan, isobutyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, sec-dodecyl mercaptan, t-butyl mercaptan, phenyl mercaptan, Thiocresol, thioglycolic acid, its ester, ethylene thioglycol, etc. are mentioned. As for the usage-amount of these molecular weight modifiers, 0.01 to 0.5 weight% is preferable based on the weight of the whole reaction mixture.

The polymerization reactor uses a device that is uniformly stirred with a stirring blade such as a double helical ribbon, a pitched burdle type or the like. The polymerization is continuously supplied to the polymerization reactor with the monomer or the monomer solution, and the polymerization reaction is carried out at a temperature of 120 to 160 ° C so that the polymerization conversion rate of the monomer is substantially constant within the range of 40 to 70%. If the polymerization conversion rate is less than 40%, the load of the devolatilization step by the volatile component is large, and may be insufficient in the devolatilization due to the limitation of the heat transfer area of the preheater, for example. On the other hand, when it exceeds 70%, piping pressure loss between a polymerization reactor and a preheater will become large, for example, and transport of a polymerization liquid will become difficult and it is unpreferable. If the polymerization temperature is less than 120 ° C., the polymerization rate is too slow to be impractical. If it exceeds 160 ° C., the polymerization rate is too fast and adjustment of the polymerization conversion rate becomes difficult. In addition, the thermal decomposition resistance is lowered, which is not preferable.

The polymerization liquid obtained by such a polymerization reaction is devolatilized and the polymer is taken out. As a devolatilization apparatus, the extruder with a multistage vent, a devolatilization tank, etc. are used. Preferably, the polymerization liquid is superheated to a temperature of 200 to 290 DEG C in a preheater or the like, and fed to a devolatilization tank under vacuum at 200 to 250 DEG C, a temperature of 20 to 100 Torr, having a sufficient space at the top, and taking out the polymer.

This polymer is continuously transferred to the extruder in the molten state, extruded from the die into the strand through the extruder, cooled with water and cut with a strand cutter to obtain a columnar polymer.

In addition, a light diffusing agent, an ultraviolet absorber, a fluorescent brightener, an antioxidant, a plasticizer, a releasing agent, a dye, a pigment, and the like may be added, if necessary, using a feed pump from the side of the extruder before extruding from the die onto the strand. .

The resin extruded plate of the present invention can be produced by melt extrusion molding. For example, the raw material resin is melted in an extruder and extruded from a T die, sequentially passed between temperature controlled 3, 4 to 5 polishing rolls, and molded into a plate (preferably flat plate), and the molded plate thereof. The resin extruded plate can be obtained as a single sheet product by cooling and solidifying while passing through the guide roll and pulling it to the take-up roll, and cutting the width direction and the flow direction to a predetermined length. At this time, although the resin extruded plate of desired plate | board thickness can be manufactured by adjusting the clearance gap and take-out speed | rate of a polishing roll, the resin extruded plate of 2-15 mm thickness is generally used for the light guide plate.

In the resin extruded plate of the present invention, it is the most important property as the light guide plate to have no cutting powder having a size of 0.1 mm 2 or more on the surface of the surface protection film. When the cutting powder is attached, the cutting powder is pressed against the surface protection film by the weight of the superimposed plate when the resin plate is loaded and transported, and a recess is formed on the surface of the resin plate, or the film is torn and scratched.

In order to strictly remove the cutting adhering to the surface protection film, the inventors found that after cutting the resin extrusion plate with a saw, it is very effective to suck and remove the cutting part while brushing the surface protection film with a rotary brush. .

In the present invention, the rotating brush is brought into contact with the surface protection film of the resin extruded plate, but the material of the filament of the brush has a suitable elasticity, flexibility and relative abrasion, and especially if the surface protection film is not damaged or peeled off from the resin plate. It is not limited. In addition to synthetic fibers such as polypropylene and nylon, natural fibers derived from plants or animals can also be used. In order to prevent generation of static electricity, it is preferable to use conductive synthetic fibers. It is important that the rotary brush be in contact over the entire width of the plate. Although there is no restriction | limiting in particular in rotation speed, Generally, the range of 100-1000 rpm is preferable. It is very important that the suction device incorporates a rotary brush and sucks immediately after brushing the plate surface to drop the cutting powder. When the rotary brush and the suction device are separately provided, the effects of the present invention are not sufficiently obtained. A suction force of 5 kPa or more is sufficient to remove a normal cutting powder (see FIG. 1 of the present invention. A represents a rotary brush, B represents a suction device cover, C represents a resin extruded plate, and D represents a suction duct. Arrow indicates the direction of extrusion).

Moreover, in order to remove the cutting powder adhering to the surface protection film, it was found that it is also very effective to stick and remove the cutting powder adhering to the surface protection film by passing the board | substrate after cutting between two upper and lower adhesive rolls. In this case, the adhesive roll can be used without particular limitation as long as the adhesive roll is kneaded or coated on the surface of elastic material such as polyurethane or synthetic rubber to apply or remove the cutting powder. . In addition, by contacting the surface protective film directly to the roll 2 for sticking and removing the cutting powder, the more adhesive roll 2 is brought into contact with the cutting powder attached to the roll 1 to the roll 2, so that the surface of the roll 1 is clean. It can also be designed in a retained aspect.

More specifically based on the embodiment of the present invention. First, each measuring method regarding the resin extruded plate which concerns on a present Example is shown below.

(Measurement of thickness of resin extrusion plate)

In the resin extruded plate 1 having a width of 1000 mm shown in FIG. 2, using the outer micrometer (MDC-25M manufactured by Mitsutoyo Mitsutoyo Co., Ltd.) at five points as the plate thickness measurement point 2 in the width direction. The thickness was measured and averaged to mm. The thickness of the extrusion direction (the arrow direction of FIG. 1) of the resin extruded board 1 was similarly measured with both ends of the plate as the plate thickness measuring point 3 at 50 mm intervals over a length of 1000 mm.

(Measuring method of bright point of light guide plate)

According to the light source device shown in FIG. 3, a cold cathode tube (made by Halison Denki) of 3 mmφ is provided on one side of the short side (150 mm length) side of the light guide plate C as the light source A in the lamphouse B. Then, Raywhite 75 (manufactured by Kimoto) was used as the light reflecting sheet D. The cold cathode tube was subjected to visual observation by applying a voltage of 12 V from a DC voltage stabilizer to observe the number of bright spots of 0.1 mm 2 or more. Ten samples are measured and averaged.

(Measuring method of brightness of light guide plate, brightness unevenness)

According to the light source device shown in FIG. 3, as a light source A in the lamphouse B, a cold cathode tube (made by Harrison Denki) having a diameter of 3 mm is provided on both end faces of the light guide plate C at a length of 319 mm. Raywhite 75 (made by Kimoto) was used as the reflective sheet (D), and two sheets of D121 (made by Tsujiden) were placed on the light guide plate as the light diffusion sheet (E). The cold cathode tube was supplied with a voltage of 12 V from a DC voltage stabilizer and turned on for 20 minutes, and then the entire light emitting surface was vertically 19 x horizontal by a luminance meter (CA-1000: Minolta) installed at a position 1 m away from the light emitting surface. The luminance of each of the measuring points obtained by dividing 19 = 361 was measured. Next, the average brightness was computed from the measured value of 361 points obtained.

Moreover, the uniformity was computed as an evaluation index of a luminance unevenness by following formula (1) from the measured value of 361 points obtained.

Uniformity (%) = minimum luminance value / maximum luminance value × 100

(Measurement method of spherical methacryl resin polymer average particle diameter)

An electronic shake-type sieve sorting instrument (electromagnetic vibration type AS200 DISIT manufactured by Mitamamura Riken Kogyo Co., Ltd.) was used. 100 g of the sample is placed on the top sieve of a sieve containing 0.5 to 0.15 mm, shaken for 10 minutes with a sieve shaker, and then spherical methacrylic resin polymers on each sieve are weighed, and the cumulative residual distribution curve It was made into the average particle diameter.

(Measuring method of long diameter, short diameter, length of columnar methacryl resin polymer)

Using the outer micrometer (MDC-25M by Mitsutoyo Corporation), the long diameter, short diameter, and length of the sample 200 particles were measured to 0.001 mm, and the average value was obtained.

(Preparation of spherical methacryl resin polymer (polymer -A))

95.0 parts by weight of methyl methacrylate, 5.0 parts by weight of methyl acrylate, 0.15 parts by weight of lauroyl peroxide, 0.25 parts by weight of n-octyl mercaptan, 130 parts by weight of deionized water, and 0.65 parts by weight of aluminum hydroxide were charged into a 200 L polymerizer. Stir and mix. The suspension polymerization was carried out at the reaction temperature of 80 ° C. for 150 minutes, and then aged at 100 ° C. for 60 minutes to substantially terminate the polymerization reaction. Subsequently, the polymerization reaction liquid was cooled to 50 degreeC, dilute acid was thrown in, the washing | cleaning dehydration drying process was carried out, and the spherical methacryl resin polymer (polymer-A) of 1.0 g / 10min of melt flow rate (ISO 1139 condition 13) was obtained. The average particle diameter of polymer-A was 0.39 mm.

(Preparation of Cylindrical Methacrylic Resin Polymer (Polymer-B))

150 ppm of 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane in a monomer mixture comprising 79.9% by weight methyl methacrylate, 5.1% by weight methyl acrylate and 15% by weight ethylbenzene; and 300 ppm of n-octyl mercaptan is added, polymerization is carried out in a fully mixed polymerization reactor for a polymerization temperature of 155 DEG C, a residence time of 2.0 hours, continuously polymerized to a polymerization conversion rate of 53%, and the polymerization liquid is continuously taken out of the polymerization reactor, Subsequently, it heated at 260 degreeC by the heating plate, and made it fall softly through the space | interval of a heating plate. The polymer was separated from the unreacted monomer and solvent by maintaining at 30 Torr, 230 ° C. in a devolatilization tank. The polymer is continuously transferred to the extruder in the molten state, extruded from the die onto the strand through the extruder, cooled with water (bath at water temperature of 60 ° C.) and cut with a strand cutter to melt flow rate (ISO 1139 condition 13) 1.0 g / 10 The cylindrical columnar methacryl resin polymer (polymer-B) was obtained. The long diameter (a), short diameter (b), and length (L) of the polymer-B were (a) 2.773 mm, (b) 2.689 mm, (L) 3.105 mm, and (b) / (a) 0.97, respectively.

<Example 1>

A mixture of 50 parts by weight of polymer-A and 50 parts by weight of polymer-B (100 parts by weight) is fed to the raw material hopper 1 of FIG. 5, and the cylinder temperature is 210, 210, 240, 250 in order from the hopper side to the die side. Melt at 150 mmφ single screw extruder (2), temperature controlled at 260, 260 ° C, discharge rate of 780 kg / hour from T die (3) with lip width 1250 mm, lip opening 10 mm, resin temperature 281 ° C. Extruded horizontally placed between four polishing rolls 4 (temperatures 89, 94, 95, 95 ° C. in sequence) and cooled while pulling the extruded plate on the guide rolls 5 to the take-up rolls 6 It was. The temperature around the extrusion line was 49 ° C. Fans and air spray devices for cooling the front and back of the plate are provided above and below the guide roll, and by adjusting these, the temperature distribution of the center, the end, and the front and back of the plate is controlled to produce a resin extruded plate with less warpage.

In the take-up roll part, the polyethylene masking (90 micrometers in thickness) made from the surface protection agent was attached to the upper and lower sides of the board, and the both ends of the board were cut | disconnected by the trimming machine 7, and it was set as 1100 mm in width. Cut to length of 1380 mm with a cross-cutting machine (8) to form a sheet, and pass through the upper and lower cutting powder suction rotary brush (9) (500 rpm, suction force of 7 kPa), and then a stocker with a conveyer (10). ), And loaded as a light guide plate product 12 on the pallet 13 in a predetermined number of sheets. In addition, the defective plate is not stacked on the pallet, and discharged by the defective discharge 14 so as not to be mixed in the product. The plate thickness was measured, and found to be 6.00 ± 0.05 mm.

In this manner, a resin extruded plate A having a thickness, width, and length of 6 × 1100 × 1380 mm was obtained. When this was observed, the cutting powder of 0.1 mm <2> or more did not adhere to the front and back.

100 sheets of this resin extruded plate were loaded on a pallet and transported by truck and ship from Fuji City, Shizuoka, Japan to Busan, Korea. Even if it observed after removing a package and a surface protection film, the recessed part or a scratch of 0.1 mm <2> or more was not seen. The resin press was cut to a size of 6 x 150 x 300 mm, and the bright point was measured.

Subsequently, the wheel extruded was cut out from the resin extruded plate A after transport in a size of 241 mm in width and 319 mm in length, and the cut surface of the cut plate was precision grinder (PLA-BEAUTY: manufactured by Megalotechnica Co., Ltd.). ), And further buff polishing to finish the mirror surface, and then using a printing screen subjected to a 15 inch dot gradation, using a medium medium SR931 (manufactured by Mino Group) with ink, one side of the light guide plate Screen printing was carried out to obtain a light guide plate. The luminance was measured and found to be 2900 cd. These results are shown in Table 1 below.

<Example 2>

A resin extrusion plate B was obtained in the same manner as in Example 1 except that the cutting powder was sucked off by inserting the plate into two upper and lower adhesive rolls without using the cutting powder suction rotating brush. Table 1 shows the measurement results of the recesses or the scratches, the cutting powders, the bright spots and the luminance.

Comparative Example 1

Resin extruded plate C was obtained in the same manner as in Example 1, except that the front and back sides were sucked with a suction force of 7 kPa without using a cutting powder suction rotary brush. Table 1 shows the measurement results of the recesses or the scratches, the cutting powders, the bright spots and the luminance.

Comparative Example 2

Resin extruded plate D was obtained in the same manner as in Example 1, except that the front and back plates were blown with compressed air without using a cutting powder suction rotary brush. Table 1 shows the measurement results of the recesses or the scratches, the cutting powders, the bright spots and the luminance.

(Summary of results)

As shown in the above examples and comparative examples, in the case of not using the cutting powder suction rotary brush or the adhesive roll of the present invention, the cutting powder remains on the surface protection film of the resin plate, and the recessed surface Since scratches occur and the occurrence of bright spots and deterioration of luminance are seen, it is not preferable as a light guide plate for a backlight unit.

The resin extruded plate of the present invention is used for a backlight device that illuminates liquid crystals from the back in a liquid crystal display as a display device such as a laptop or desktop personal computer, a portable information terminal, a game machine, a workstation, an image monitor, or a television. It can use suitably as a light guide plate used.

Claims (7)

A resin sheet having a surface protective film adhered to a plate, no cutting powder having a size of at least 0.1 mm 2, and no recesses and / or scratches having a size of at least 0.1 mm 2 on the surface of the plate. The resin extrusion plate of Claim 1 whose raw material resin is methacryl resin, polycarbonate, or alicyclic polyolefin. The resin extrusion plate of Claim 1 whose raw material resin is spherical methacryl resin and whose average particle diameter is 0.2-0.5 mm. The resin extruded plate according to claim 1, wherein the plate thickness is 2 to 15 mm. After extruding into a plate shape using molten resin, the molded plate is cooled and solidified while pulling on the take-up roll through the guide roll, and the surface protection film is adhered to the front and back, and then the width direction and the flow direction are predetermined lengths. A method for producing a resin extruded plate, comprising: cutting a powder onto a surface protective film by sucking and removing the cutting powder while brushing the surface protective film with a rotary brush after cutting. After extruding into a plate shape using molten resin, the molded plate is cooled and solidified while pulling on the take-up roll through the guide roll, and the surface protection film is adhered to the front and back, and then the width direction and the flow direction are predetermined lengths. In the manufacturing method of the resin extruded plate cut | disconnected by the cutting, WHEREIN: The board | substrate after cutting is made to pass between two upper and lower adhesive rolls, and it adhere | attaches and removes the cutting powder adhered to a surface protection film, so that there is no cutting powder on a surface protection film. Manufacturing method. The manufacturing method of the resin extruded board of Claim 5 or 6 which includes the process of shape | molding in plate shape through the temperature controlled 3 to 5 polishing rolls one by one.

Images