JP2009184266A - Molding system of polycarbonate resin molded article, molding process, and polycarbonate resin molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polycarbonate resin molded article and a manufacturing process thereof in which yellow coloring is prevented and hue is excellent. <P>SOLUTION: A polycarbonate resin composition is subjected to extruding molding to give pellets, and the pellets are subjected to injection molding to give a transparent polycarbonate resin molded article. In a screw, etc. of a molding system, a film having oxidation-starting temperature of 700°C or higher is formed. The obtained transparent polycarbonate resin molded article may be subjected to annealing under heating. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a molding apparatus and molding method suitable for molding a transparent polycarbonate resin molded body, and a polycarbonate resin molded body molded by this method.

  Polycarbonate resins are excellent in mechanical properties, heat resistance and weather resistance, and have high light transmittance, and thus are used in a wide range of applications. Such applications include, for example, a light guide plate for a sidelight system for a mobile phone in a liquid crystal display, a light diffusing plate for a direct-type backlight system surface light source for a liquid crystal television, a recording medium such as a CD and a DVD, and a camera. And glasses and sunglasses lenses.

  In the liquid crystal display device, there is an increasing demand for higher luminance as the display area increases, and recently, in view of the environmental problem of eliminating mercury, LEDs are increasingly used instead of conventional fluorescent tubes. Since the fluorescent tube is a linear light source, in the side light type light guide plate, 1 to 3 fluorescent tubes are arranged on the end surface of the light guide plate to control the light output direction, thereby forming a planar light source body. However, since the LED is a point light source, it needs several tens of times as many as one fluorescent tube. For this reason, the total amount of heat of the backlight unit using the LED increases, and the light guide plate made of acrylic resin has insufficient heat resistance and may melt.

  A light guide plate made of polycarbonate resin having excellent heat resistance is superior in terms of quality such as impact resistance and dimensional stability as compared with a light guide plate made of acrylic resin.

  The screen size of light guide plates is increasing year by year. In the case of the side light type polycarbonate resin light guide plate, when the size is increased, a long optical path is formed, and thus a hue such as a yellow transparent characteristic of polycarbonate is affected. For example, when a light guide plate is used for a planar light source body, the light emission color becomes yellow light, and a white LED has the strongest spectral peak particularly at 460 nm (blue), so that light is absorbed and luminance is lowered. There's a problem.

  Such a problem becomes more prominent when the temperature at the time of injection molding becomes high (for example, 350 ° C. or more).

  Further, in the case of a molded body such as a lens molded by injection molding, the molding cycle is lengthened to about 5 minutes due to the thick wall thickness, which also causes yellowing. That is, if the resin material stays in the molding machine cylinder for 5 minutes or more for a long time of 5 minutes or more, the resin and additives are easily decomposed and colored yellow.

  As the light diffusing plate for liquid crystal television, a polycarbonate resin plate having a thickness of 2 mm to which 3 to 4 wt% of light diffusing particles are added is used. Many fluorescent tubes are arranged at intervals of about 25 mm so as to face the back surface of the light diffusion plate. This light diffusing plate has a relatively short optical path and a higher luminance than that of the fluorescent tube. However, if the number of fluorescent tubes is reduced or changed to the side light type, the light path becomes longer, and the yellow transparent hue peculiar to polycarbonate becomes a problem.

  As a measure against hue, a blueing treatment may be performed by adding a dye or pigment to a polycarbonate resin, but the blue light of the light from the light source is absorbed, so that the luminance is lowered.

  In the case of a lens made of a polycarbonate resin, since humans generally prefer blue, yellow, which is a contrasting color, is avoided, and blueing treatment is performed in which a blueing agent is added to the molding material. Polycarbonate lenses are relatively thick, and the hue is easily recognized by general consumers, so the density of bluing is high. For this reason, problems such as discoloration of the bluing agent during injection molding, and damage to the mold due to gas, increasing durability and maintenance frequency, are occurring.

  In JP-A-8-132437, in order to suppress yellowing (yellowing) of an extruded polycarbonate resin, a large amount of nitrogen is continuously supplied into a hopper for storing a molding resin. It is described that the oxygen concentration inside is less than 0.1%.

  Japanese Patent Application Laid-Open No. 9-59367 describes supplying nitrogen gas in an amount of 0.1 to 20 NL (normal liters) to 100 g of polycarbonate resin in a kneading part of an extruder in order to improve hue stability. ing.

  However, it is not preferable to use a large amount of nitrogen gas as described above because it causes a high cost.

  Japanese Patent Application Laid-Open No. 2001-341164 discloses that nitrogen gas is supplied into a thermoplastic resin supply hopper attached to an injection cylinder to control the oxygen concentration in the hopper, thereby preventing yellowing of a molded product. However, there is no description on how much the oxygen concentration level in the hopper is.

Media such as CD and DVD, one of the big markets for polycarbonate resin, is injection-molded at a high temperature exceeding 350 ° C, but the hue is clear and transparent even though the cycle is less than 5 seconds and the effect of retention is small. It is. However, since the reading is a laser, its hue is not a problem. Regarding media, it is desirable that foreign matter does not increase by injection molding rather than hue.

As a countermeasure against these problems, JP-A-4-208428 discloses that a film made of SiC, TiC, TiN, or WS is provided on the surface of a peripheral member of a screw body and a backflow prevention ring of an injection molding machine.

JP-A-2-276039 discloses that an alloy lining made of Co—Ni—Mo—Cr is formed on the inner wall of a cylinder of an injection molding machine, and a two-layer coating of TiC and TiN is performed on the screw surface.

By providing a coating (coating) in this way, it becomes difficult to generate burns and carbides due to staying in the molding machine, or it becomes non-adhesive and thus easily peels off. As a result, it is possible to reduce foreign matters that are regarded as problems in optical disks.

These known documents disclose that a non-adhesive film is formed with polycarbonate to prevent the generation of foreign substances due to burning, but nothing is mentioned about improvement of yellow transparent hue.

Japanese Patent Application Laid-Open Nos. 7-178781 and 2002-86520 disclose that a cylinder or screw for injection molding is coated with fluororesin, fluorocarbon dispersion plating, or TiN for reducing peelability and frictional resistance. However, these documents are also intended to reduce foreign matter by forming a film having excellent peelability, similar to the above-mentioned documents. These documents do not mention measures against yellowing of the polycarbonate resin.
JP-A-8-132437 JP-A-9-59367 JP 2001-341164 A JP-A-4-208428 JP-A-2-276039 JP 7-178781 A JP 2002-86520 A

  The present invention eliminates the problems of the prior art as described above, and an apparatus and method for molding a light-transmitting polycarbonate resin molded article that is prevented from yellowing and has a good hue, and a polycarbonate molded by this method It aims at providing the resin molding.

  A molding apparatus for a polycarbonate resin molded body of the present invention (Claim 1) is a molding apparatus for a polycarbonate resin molded body that melts and molds a polycarbonate resin composition, and the surface in contact with the molten polycarbonate resin composition is in the atmosphere. Is covered with a film having an oxidation start temperature of 700 ° C. or higher.

  The molding apparatus according to claim 2 is the molding apparatus according to claim 1, wherein the molding apparatus is an injection molding machine or an extruder, and a contact surface with the molten polycarbonate resin is a screw surface, a barrel inner surface, a plunger surface, a screw head surface, It is characterized in that it is at least part of the reverse flow prevention ring surface, the sheet ring surface, the nozzle inner surface, the die inner surface, and the molten polycarbonate resin flow path.

  The molding apparatus according to claim 3 is the molding apparatus according to claim 1 or 2, wherein the coating is at least one selected from the group consisting of Pt, Au, TiAlN, TiSiN, AlCrN, CrSiN, TiBN, AlCrSiN, AlZrN, AlZrSiN, and CrBN. It is a seed film.

  According to a fourth aspect of the present invention, there is provided a molding apparatus for a polycarbonate resin molded body according to any one of the first to third aspects, wherein an oxidation start temperature of the film in the atmosphere is 850 ° C. or higher.

  The method for molding a polycarbonate resin molded body of the present invention (invention 5) is characterized in that the polycarbonate resin molded body is molded using the molding apparatus according to any one of claims 1 to 4. .

  The method for molding a polycarbonate resin molded body according to claim 6 is the method according to claim 5, wherein the polycarbonate resin composition includes a polycarbonate resin and a phosphorus compound, and the ratio of the phosphorus compound in the resin material is It is 0.02-0.3 weight part with respect to 100 weight part of polycarbonate resin, The moisture content of this polycarbonate resin composition is 130 ppm or less, It is characterized by the above-mentioned.

  According to a seventh aspect of the present invention, there is provided a method for molding a polycarbonate resin molded body according to the sixth aspect, wherein the phosphorus compound is a phosphorus heat stabilizer.

  The method for producing a light-transmitting polycarbonate resin molded article according to claim 8 is characterized in that, in claim 6 or 7, the water content of the resin material is 100 ppm or less.

  According to a ninth aspect of the present invention, there is provided a method for molding a polycarbonate resin molded body according to any one of the sixth to eighth aspects, wherein the polycarbonate resin composition is vacuum-dried.

  A method for molding a polycarbonate resin molded body according to a tenth aspect is the method according to any one of the fifth to ninth aspects, wherein the polycarbonate resin composition is stored in a hopper, and the hopper is passed through a resin supply path. A method of forming a light-transmitting polycarbonate resin molded body in which the resin is supplied to an injection molding machine and nitrogen gas is supplied under the hopper which is a connecting portion between the hopper and the resin supply path The oxygen concentration in the hopper is 0.2 to 5.0% by volume.

  The method for molding a polycarbonate resin molded body according to an eleventh aspect is characterized in that in any one of the fifth to tenth aspects, the injection molded molded body is heated and annealed.

  The polycarbonate molded product of the present invention (Claim 12) is formed by the method according to any one of Claims 5 to 11.

A conventionally used surface treatment film is oxidized under a general molding temperature (for example, about 270 to 370 ° C.) or pressure of a polycarbonate resin composition to form an oxide film.

When the polycarbonate resin end group reacts with this oxide film, a trace amount of yellow substance is generated, and the polycarbonate resin becomes a characteristic yellow transparent.

In contrast, in the present invention, in a molding apparatus such as an injection molding machine or an extrusion molding machine for molding a polycarbonate resin composition, the surface of the part in contact with the molten polycarbonate resin has an oxidation start temperature in the atmosphere of 700. By covering with a film at a temperature of 0 ° C. or higher, the yellow transparency unique to the polycarbonate resin can be made almost colorless and transparent.

  In the present invention, the phosphorous compound is contained in an amount of 0.02 to 0.3 parts by weight based on 100 parts by weight of the polycarbonate resin, and the water content is preferably 130 ppm or less, more preferably 120 ppm or less, and even more preferably 100 ppm or less. By molding this polycarbonate resin composition, it is possible to obtain a polycarbonate resin molded body in which yellowing is more reliably prevented. About this reason, it is guessed that it is because oxygen in a water | moisture content reacts with polycarbonate resin, and it is suppressed that yellowing arises.

  When a phosphorus heat stabilizer is used as the phosphorus compound, light transmittance and hue are improved.

  The resin material can sufficiently reduce the water content easily by vacuum drying.

  Nitrogen gas is supplied under the hopper, which is a connecting portion between the resin supply path for supplying the resin material from the hopper for storing the resin to the molding machine, and the hopper so that the oxygen concentration in the hopper is 5.0% by volume or less. As a result, yellowing of the polycarbonate resin is further sufficiently prevented.

  It is sufficient that the oxygen concentration in the atmosphere in the hopper is 6.0% by volume or less, and may be 0.2 to 5.0% by volume, which is higher than those in Patent Documents 1 and 2. Thus, since it is not necessary to make the oxygen concentration so low, the amount of nitrogen gas used is smaller than that in Patent Documents 1 and 2, and the manufacturing cost is reduced.

  By light-molding the resin material, a light guide plate, a light diffusion plate, lenses, and the like are manufactured.

  By heating and annealing the molded polycarbonate resin molded body, the translucency of the molded body can be increased.

Thus, according to the present invention, it is possible to provide a high-quality polycarbonate molded body that is colorless and transparent and excellent in heat resistance, strength, and dimensional stability. In addition, productivity can be improved and costs can be reduced by improving maintainability and reducing additives.

  Hereinafter, the present invention will be described in detail.

  The molding apparatus for a polycarbonate resin molded body of the present invention is a molding apparatus for a polycarbonate resin molded body for melting and molding a polycarbonate resin composition. The surface in contact with the molten polycarbonate resin composition has an oxidation start temperature in the atmosphere. It is characterized by being coated with a film of 700 ° C. or higher.

  The molding method of the polycarbonate resin molding of the present invention is to perform molding using this molding apparatus.

  The polycarbonate resin molded body of the present invention is molded by this molding method.

[Polycarbonate resin composition]
<Polycarbonate resin>
The polycarbonate resin used in the present invention is, for example, an interfacial polymerization method (phosgene method) in which an aromatic dihydroxy compound or a small amount of a polyhydroxy compound is reacted with phosgene, or a melting method (transesterification method) in which a carbonic acid diester is reacted. And a linear or branched thermoplastic polymer or copolymer.

  As aromatic dihydroxy compounds used as raw materials, 2,2-bis (4-hydroxyphenyl) propane (ie, bisphenol A), 2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane (ie, tetramethyl) are used. Bis (4-hydroxyphenyl) alkane-based dihydroxy compounds such as bisphenol A), 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane (ie, tetrabromobisphenol A), 2,2-bis (4 -Hydroxy-3,5-dichlorophenyl) propane (ie, tetrachlorobisphenol A) and other bis (4-hydroxyphenyl) alkane dihydroxy compounds containing halogen, 1,1-bis (4-hydroxyphenyl) cyclohexane, hydroquinone , Resorcino Le, such as 4,4-dihydroxydiphenyl and the like. Among them, a bis (4-hydroxyphenyl) alkane dihydroxy compound which may contain a halogen is preferable, and bisphenol A is particularly preferable. These aromatic dihydroxy compounds may be used individually by 1 type, or several types may be suitably selected and used in arbitrary ratios.

  In order to adjust the molecular weight of the polycarbonate resin as appropriate, a molecular weight regulator may be added. As the molecular weight regulator, monovalent aromatic hydroxy compounds can be used. Specifically, m- and p-methylphenol, m- and p-propylphenol, p-bromophenol, p-tert- Examples include butylphenol and p-long chain alkyl-substituted phenol. These may be used alone or in combination of two or more. Although this molecular weight regulator can be added in any amount, it is preferable to add it so that the polycarbonate resin has the following viscosity average molecular weight.

  The viscosity average molecular weight of the polycarbonate resin composition used in the present invention is preferably about 12,000 to 30,000, particularly about 14,000 to 30,000. When this viscosity average molecular weight is too low, the toughness of the obtained molded product is lowered and may not be practical. On the other hand, even if it is too high, the flowability of the aromatic polycarbonate resin composition is lowered, so that injection molding is limited to application to thick parts and may not be applicable to large parts.

The viscosity average molecular weight (Mv) in the present invention is determined by measuring the viscosity of a methylene chloride solution of a polycarbonate resin at 20 ° C. using an Ubbelohde viscometer to determine the intrinsic viscosity (η). Indicates the value calculated from the formula.
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83

<Phosphorus compounds>
The polycarbonate resin composition used in the present invention preferably contains 0.02 to 0.3 parts by weight, particularly preferably 0.03 to 0.1 parts by weight, of a phosphorus compound with respect to 100 parts by weight of the polycarbonate resin. . As the phosphorous compound, a phosphorous heat stabilizer is preferable in order to improve the light transmittance and hue of the polycarbonate resin composition. As the phosphorus-based heat stabilizer, phosphite ester, phosphate ester and the like are preferable.

  Examples of phosphites include triphenyl phosphite, trisnonylphenyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, trinonyl phosphite, tridecyl phosphite, and trioctyl phosphite. , Trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tricyclohexyl phosphite, monobutyl diphenyl phosphite, monooctyl diphenyl phosphite, distearyl pentaerythritol diphosphite, bis (2,4-di-tert -Butylphenyl) pentaerythritol phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol phosphite, 2,2-methylenebis (4,6-di-tert) Butylphenyl) triesters of phosphorous acid such as octyl phosphite, diesters and monoesters, and the like.

  Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris (nonylphenyl) phosphate, 2-ethylphenyl diphenyl phosphate, tetrakis (2,4-di-). tert-butylphenyl) -4,4-diphenylene phosphonite.

  Among these phosphorus compounds, distearyl pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol phosphite, bis (2.6-di-tert-butyl-4-methyl) Phosphites such as phenyl) pentaerythritol phosphite and tris (2,4-di-tert-butylphenyl) phosphite are preferred, and among them bis (2,6-di-tert-butyl-4-methylphenyl) penta Particularly preferred are phosphites such as erythritol phosphite and tris (2,4-di-tert-butylphenyl) phosphite. In addition, a phosphorus compound may be used individually and may use 2 or more types together.

  The compounding amount of the phosphorus-based heat stabilizer is 0.02 to 0.3 parts by weight, preferably 0.03 to 0.1 parts by weight, and more preferably 0.04 to 0.00 parts by weight with respect to 100 parts by weight of the polycarbonate resin. 05 parts by weight. If the amount of the phosphorous heat stabilizer is less than 0.02 part by weight, the effect is small, and if it exceeds 0.3 part by weight, no further effect of addition is observed, but rather hydrolysis tends to occur. .

<Moisture content of polycarbonate resin composition>
The polycarbonate resin composition used in the present invention preferably contains the polycarbonate resin and a phosphorus compound, and has a water content of 130 ppm or less, particularly 120 ppm or less, more preferably 100 ppm or less, particularly 80 ppm or less.

  In either case of injection molding or extrusion molding, by setting the moisture in the resin material to 130 ppm or less, it is possible to prevent the molded body from yellowing due to reaction between oxygen in the moisture and the polycarbonate resin.

  In the present invention, the moisture content is a value measured with a Karl Fischer moisture meter for polycarbonate resin pellets or flakes.

  In order to make the water content in the resin material not more than the above value, the resin material is preferably dried by vacuum drying, hot air drying or the like. In addition, a water content can be easily made into 100 ppm or less by vacuum-drying at 10 kPa or less and 90-130 degreeC with a vacuum dryer for 2 hours or more, for example, 3 to 4 hours. The moisture content can be reduced to 80 ppm or less by drying for 2 hours or more at 100 to 130 ° C. using a vacuum dryer whose pressure is reduced to the absolute vacuum.

  In ordinary polycarbonate resin injection molding, the pellets are dried at 120 ° C. for 4 hours or longer with a hot air circulating dryer, but 130 ppm of water remains in the pellets. Even if it is carried out at 135 ° C. where the polycarbonate resin pellets are slightly melted and not blocked, the water content hardly decreases. Even in such a state containing a large amount of moisture, there is no occurrence of silver streaks known as defective molding, and molding is usually performed without any problem. However, in the case of injection molding with this water content, even if the resin temperature is set at about 290 ° C., oxygen in the water reacts with the polycarbonate to cause yellowing.

  When a film having a high oxidation start temperature is provided on the part to be molded with the molten polycarbonate resin composition, yellowing is prevented even when about 130 ppm of water is present in the pellet. However, when the molding conditions (temperature, cycle, etc.) become severe, yellowing is likely to occur even if the film is provided. In such a case, yellowing can be prevented by setting the moisture in the pellet to 120 ppm or less, particularly 100 ppm or less, and particularly 80 ppm or less.

  The same applies to the case of using flakes instead of polycarbonate resin pellets.

<Additives>
Various additives such as fine particles and fluorescent brightening agents can be added to the polycarbonate resin composition depending on the function and application.

≪Fine particles≫
When the light-transmitting polycarbonate resin molding of the present invention is used as a light diffusing plate, fine particles for light diffusion are added.

  As fine particles, various types used as a light diffusing agent can be appropriately selected and used. Specifically, various particles of an inorganic compound or an organic compound can be used, and although there is no particular limitation, the weight average particle size is preferably 0.7 to 30 μm, particularly 1 to 20 μm, especially about 2 to 10 μm. . Here, the measurement of a weight average particle diameter is performed by the Coulter method (Coulter Multisizer), for example.

  If the weight average particle size is extremely small, the light diffusibility of the resin composition may be inferior, the light source may be seen through, or the visibility may be inferior. On the other hand, if the average particle size is extremely large, the diffusion effect with respect to the addition amount is low, so that the luminance may decrease.

  Specific examples of the fine particles include inorganic fine particles such as barium sulfate, talc, calcium carbonate, silica, and glass; silicone resins, acrylic resins, benzoguanamine resins, styrene resins, butadiene resins, and the like. Organic fine particles. Among these, organic fine particles are preferable.

  The organic fine particles are preferably organic fine particles having a crosslinked structure in which the main chains constituting the organic polymer are cross-linked, and in particular, there is no practical deformation during the processing of the polycarbonate resin molded body of the present invention, for example, injection molding. What maintains the fine particle state is preferable.

  That is, as the organic fine particles, those that do not substantially melt in the polycarbonate resin even when heated to the molding temperature of the polycarbonate resin (for example, about 360 ° C.) are preferable. Such fine particles include organic fine particles of cross-linked acrylic resin and silicone resin. Among them, polymer fine particle poly (butyl acrylate) core / poly (methyl methacrylate) based on partially cross-linked methyl methacrylate A polymer having a shell and a core having a core / shell monoholgy including a core of a rubber-like vinyl polymer and a shell are preferred.

From the viewpoint of light diffusibility, the fine particles preferably have a refractive index difference (Δn) of 0.01 or more from the aromatic polycarbonate resin (A) and are incompatible with the polycarbonate resin (A). . Here, the refractive index is a refractive index with respect to d-line (587.562 nm, He) at a temperature of 25 ° C. In actual measurement, the refractive index (n _pc ) of the polycarbonate resin is measured by the V-block method (manufactured by Kalnew Optical Co., Ltd., type KPR), and the refractive index (n _ld ) of the fine particles is measured by the Becke method (method for comparison with a standard solution) ).

  The refractive index difference is 0.05 to 0.5, particularly 0.07 to 0.5 in order to suppress problems such as the light source disposed behind the light diffusing plate being seen through and to ensure sufficient luminance. It is preferably about 0.3. By setting the difference in refractive index within this range, light diffusibility is sufficient.

  In addition, the refractive index of the aromatic polycarbonate resin which consists of bisphenol A suitable as a polycarbonate resin used for this invention is about 1.58.

  The blending amount of the fine particles is preferably about 0.1 to 20 parts by weight, particularly about 0.5 to 5 parts by weight with respect to 100 parts by weight of the polycarbonate resin. If the blending amount of the fine particles is too small, the light diffusibility is insufficient and the problem that the light source can be seen easily occurs. Conversely, if the blending amount is too large, the light transmittance decreases and it becomes difficult to obtain sufficient luminance.

≪Fluorescent whitening agent≫
The polycarbonate resin composition used in the present invention may contain a fluorescent brightening agent. The fluorescent whitening agent has an action of absorbing energy in the ultraviolet part of light and radiating this energy to the visible part. For example, examples of the fluorescent whitening agent include conventionally known white organic light emitters and blue organic light emitters for organic EL, in addition to conventionally known fluorescent dyes.

  The fluorescent brightening agent comprising a fluorescent dye is not particularly limited as long as it is used for improving the color tone of a synthetic resin to white or bluish white. For example, benzoxazole, stilbene, benzimidazole, Examples include naphthalimide-based, rhodamine-based, coumarin-based, and oxazine-based compounds.

  Among these fluorescent dyes, white or blue fluorescent dyes selected from benzoxazole compounds and coumarin compounds are preferable from the viewpoint of thermal stability. Specifically, from the viewpoint of heat resistance, the molecular weight is 300. A so-called high molecular weight fluorescent dye having a molecular weight of about ˜1000 is preferred, and benzoxazole compounds and coumarin compounds are particularly preferred.

  Specific examples of the benzoxazole-based compound include 4- (benzoxazol-2-yl) -4 ′-(5-methylbenzoxazol-2-yl) stilbene and 4,4′-bis (benzoxazole-2). -Yl) stilbene, 4,4′-bis (benzoxazol-2-yl) furan and the like, among others, stilbene benzoxazoles such as 4,4′-bis (benzoxazol-2-yl) stilbene Compounds are preferred.

  Specific examples of the coumarin compound include 3-phenyl-7-aminocoumarin, 3-phenyl-7- (imino-1 ′, 3 ′, 5′-triazine-2′-diethylamino-4′-chloro). -Coumarin, 3-phenyl-7- (imino-1 ', 3', 5'-triazine-2'-diethylamino-4'-methoxy) -coumarin, 3-phenyl-7-naphthotriazole coumarin, 4-methyl- Examples thereof include 7-hydroxycoumarin, and among them, phenylallyl triazolyl coumarin-based compounds such as 3-phenyl-7-naphthotriazole coumarin are preferable.

  Examples of white organic light emitters and blue organic light emitters include distyryl biphenyl blue fluorescent light emitting material, arylethynylbenzene blue fluorescent light emitting material, kinkipyridine fluorescent light emitting material, sexiphenyl blue fluorescent light emitting material, and dimesitylboryl. Anthracene-based fluorescent light-emitting material, quinacridone-based fluorescent light-emitting material, and the like can be given.

  The addition amount of the optical brightener is 0.0005 to 0.1 parts by weight with respect to a total of 100 parts by weight of the polycarbonate resin and the fine particles, and preferably 0.001 to 0.1 parts by weight. Furthermore, it is preferable to set it as 0.001-0.05 weight part, especially 0.005-0.02 weight part. If the addition amount is small, there may be cases where sufficient surface light emission and color tone improvement effect commensurate with the addition may not be obtained. On the other hand, if it is too much, the color tone improvement effect on the light emission surface is small, and the Hue) may be uneven.

≪Other additives≫
Various additives can be further blended in the polycarbonate resin composition of the present invention. Examples of additives include UV absorbers, antioxidants, mold release agents, antistatic agents, colorants, heat stabilizers, fluidity improvers, flame retardants such as decabromodiphenylene ether, antimony trioxide, and the like. Examples include flame retardant aids and anti-agglomeration agents. As the ultraviolet absorber, for example, triazole, acetophenone, salicylic acid ester and the like can be used.

[Production method of polycarbonate resin composition pellets or flakes]
The polycarbonate resin composition is mixed with a predetermined amount of an additive added to the polycarbonate raw material resin as necessary, preferably further kneaded, then preferably extruded, and further formed into pellets or flakes by cutting or the like. . As the mixing and kneading apparatus, those applicable to ordinary thermoplastic resins are adopted. For example, a ribbon blender, a Henschel mixer, a Banbury mixer, a drum tumbler, a single screw extruder, a twin screw extruder, a multi-screw screw. An extruder or the like can be used. The temperature condition of kneading is usually 230 to 300 ° C, preferably 235 to 280 ° C, more preferably 240 to 260 ° C.

<Molding machine>
Examples of a molding machine for molding a molded body from the polycarbonate resin composition include an injection molding machine and an extrusion molding machine. The injection molding machine may be an injection compression molding machine. Specifically, as the injection molding machine, an in-line type injection molding machine, a pre-plastic injection molding machine, or the like can be used. In order to perform the injection molding, the resin composition pellets or flakes may be melt-plasticized, the resin material is injected from the injection molding machine into a mold having a desired shape, solidified by cooling, and demolded.

  In order to perform the extrusion molding, for example, a die is attached to a die of an extrusion molding machine and the profile extrusion molding is performed.

  It is also possible to extrude the polycarbonate resin composition into a sheet shape, and mold the obtained sheet into a desired shape by vacuum forming or pressure forming.

<Film>
In a molding apparatus such as an injection molding machine or an extrusion molding machine for molding the polycarbonate resin of the present invention, the contact surface with the molten polycarbonate resin composition preferably has an oxide film formation temperature in the atmosphere of 700 ° C. or higher. Must be coated with a film of 850 ° C. or higher.

In the case of an injection molding machine, at least a screw surface, a barrel inner surface, a screw head surface, a backflow prevention ring surface, a sheet ring surface, a nozzle inner surface, and a pre-plastic injection molding machine at least a screw surface, a barrel inner surface, and a plan for an inline injection molding machine. The surface of any one of the jar surface, the inner surface of the nozzle, and the flow path from the screw to the plunger is preferably covered with this coating.

In the case of an extruder, the surface treatment is preferably performed on any of the screw surface, the barrel inner surface, and the die inner surface.

In particular, since the screw has a large contact area with the polycarbonate resin composition and easily generates shearing heat, it is desirable that the screw is coated with the above film.

  The material constituting the film is preferably a material in which an oxide film is not formed on the surface even when subjected to a heating test in the atmosphere at 700 ° C., and as the film, Pt, Au, TiAlN, TiSiN, AlCrN, CrSiN, TiBN, AlCrSiN, AlZrN, AlZrSiN, CrBN are mentioned.

  The film should just be formed in at least 1 layer, and may be a multilayer. For example, a film made of CrN having excellent adhesion to a metal may be formed, and a film such as TiSiN may be formed thereon, or thin films may be alternately multilayered, but the surface is the above thin film. By adopting such a film configuration, the adhesion with the underlying metal becomes stronger.

  Note that the thin films may be multilayered by various combinations.

  Examples of the method for forming a film include physical vapor deposition methods (PVD methods) such as vacuum deposition methods, sputtering methods, ion plating methods, ion beam deposition methods, and IVD methods (ion vapor deposition methods). be able to. Particularly preferred is the ion plating method.

  As a film thickness, 1-30 micrometers is preferable. Further, the surface roughness of the film is preferably Ra: 1.0 μm or less. By reducing the surface roughness in this way, the contact area with the molten resin can be reduced and shearing force can be prevented from being generated.

As a method for measuring the oxidation start temperature of the film, a film was formed on a thin plate substrate (10 × 5 × 0.1 mm) made of Pt to a thickness of about 2 μm, and the Pt group on which the film was formed The material is heated using a thermogravimetric balance at a heating rate of 10 ° C./min, and the change in weight during the heating process is measured. The temperature at which the weight begins to increase is defined as the oxidation start temperature.

Note that a film made of SiC, TiC, TiN, WS, or a multilayer thereof has an oxidation start temperature in the atmosphere of 450 to 650 ° C., which is sufficiently higher than the temperature at the time of molding. However, in the actual molding process, it was recognized that an oxide film was actually generated even in a considerably low temperature range due to pressure, contact with polycarbonate resin, shear heat generation, and the like.

For example, after performing short-term injection molding at a temperature of 360 ° C. using a CrN screw having an oxide film formation temperature of 550 ° C. in the atmosphere, the screw was removed, and observation was made. It was confirmed that the surface showed interference color and cloudiness, and that oxidation deterioration was progressing at a relatively low temperature inside the injection molding machine.

<Base metal> In the injection molding machine and the extruder, carbon steel, stainless steel, die steel, tool steel and the like that are usually used are used as the base metal on which the film is formed. In particular, those having an HRC hardness of 50 or more are preferable because they are difficult to be scratched even after surface treatment and have excellent durability. Regarding the barrel, it is preferable to use a Ni alloy and a Co alloy obtained by a generally known centrifugal casting method because they are dense.

<Nitrogen gas supply>
In general, an injection molding machine includes an injection cylinder and a hopper for storing a resin material supplied to the cylinder.

  In the present invention, the transparency of the molded body can be increased by supplying nitrogen gas below the hopper that supplies the resin material to the cylinder and lowering the oxygen concentration in the atmosphere under the hopper and in the hopper. it can.

  In a normal injection molding machine, a resin supply path for supplying a resin material from a hopper for storing the resin material to an injection cylinder and a connecting portion between the hopper, that is, a portion immediately before plasticizing the resin material with a screw is provided. This is called under the hopper, and the material is supplied to the screw from here. In addition, a material hopper or a transport hopper (in this case, a temporary stock point for transport to a plasticizing section such as a hopper dryer, loader, hose, etc.) is installed at the top.

  Since nitrogen gas is lighter than air, the nitrogen gas introduction site is preferably below the hopper. The oxygen concentration is preferably confirmed by measuring with an oximeter attached to the hopper. In the case of supplying nitrogen gas, it is preferable that a portion where air flows, such as an opening of a hopper or a joint, is completely closed by using an O-ring, a sealant, or the like so as to be almost sealed. Further, when a hose such as a hopper loader is connected for continuous molding, it is difficult to seal it. Therefore, it is preferable to temporarily provide a metal shutter at the hopper stock portion and seal it for a certain period of time.

  The reason why yellowing is suppressed by supplying nitrogen under the hopper is considered to be because the oxidation reaction of the polycarbonate resin is suppressed by lowering the oxygen concentration.

  In the present invention, when nitrogen gas is supplied under the hopper as described above, the oxygen concentration in the hopper is preferably 6.0% by volume or less, particularly preferably 0.2 to 5.0% by volume.

  In the present invention, a sufficiently transparent polycarbonate resin molded product can be produced without supplying nitrogen gas under the hopper or the like, but nitrogen gas is supplied so that the oxygen concentration in the hopper is within the above range. By doing so, a polycarbonate resin molded body having sufficiently high transparency can be produced.

  Since the above oxygen concentration range is higher than those in Patent Documents 1 and 2, the amount of nitrogen gas used can be greatly reduced. Therefore, running costs can be reduced, and the safety of work in a clean room can be increased.

[Annealing treatment]
The obtained polycarbonate resin molded body is heated and annealed using a hot air circulating dryer, dehumidifying dryer, vacuum dryer, far-infrared heater, etc., so that the distortion inside the molded body is removed, and multiple molded products are removed. Refraction is reduced and transparency can be enhanced. In particular, when used in an optical component, the luminance is improved more than usual, and the transmission characteristics and the light collection characteristics are also improved.

  The heat treatment is preferably performed at 110 to 140 ° C., particularly 120 to 130 ° C., for 0.2 to 5 hours, particularly 0.5 to 4 hours, but is not limited thereto.

[Total light transmittance (%)]
According to the molding apparatus and molding method of the present invention, it is possible to mold a highly transparent polycarbonate resin molded article having a total light transmittance of 65% or more, particularly 67% or more at a length of 300 mm.

[Usage of transparent polycarbonate resin moldings]
Applications of the transparent polycarbonate resin molded body include a light guide plate and a diffusion plate incorporated in a backlight for a liquid crystal device. In addition, this polycarbonate resin molded body includes glasses lenses, sunglasses lenses, camera lenses, various lenses including fθ lenses, security camera dome covers, automotive clearance lamps and meters, pachinko parts, various light guides including displays, It can be applied to light transmissive parts such as headlamps and tail lamps.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

The raw materials used in Examples and Comparative Examples are as follows.
Polycarbonate resin Made by Mitsubishi Engineering Plastics
"Iupilon H4000F" (viscosity average molecular weight 16000)
Phosphorus compound (stabilizer) “PEP-36” manufactured by Asahi Denka Co., Ltd. (2,6-di-tert)
-Butyl-4-methylphenyl) -pentaerythritol
Di-phosphite

The oxidation start temperatures of the films formed in Examples and Comparative Examples are as follows.
TiSiN: 1100 ° C AlZrN: 1300 ° C or higher AlCrSiN: 1100 ° C CrSiN: 1000 ° C Au: 1300 ° C or higher TiN; 450 ° C TiCN; 350 ° C CrN; 550 ° C

[Example 1]
After adding 0.05 parts by weight of the phosphorus compound to 100 parts by weight of the polycarbonate resin and mixing, the cylinder temperature was measured with a single screw extruder with a screw diameter of 40 mm (“VS-40” manufactured by Tanabe Plastic Machinery Co., Ltd.). A strand was melt-kneaded and extruded at 250 ° C. to obtain a strand, which was cut to obtain pellets of a resin material. At that time, supply nitrogen from below the hopper, attach an oxygen concentration meter to the hopper, seal the fitting member and the part with a gap with an O-ring or sealant, and adjust the nitrogen flow rate so that the oxygen concentration in the hopper becomes 2%. It was adjusted.

  The screw of this extruder is a coated screw in which a cold tool steel KPS6 (manufactured by Nippon High Frequency Steel Co., Ltd.) is formed by depositing 4 μm of CrN on the base by arc ion plating and forming 2 μm of TiSiN on the surface. The barrel was centrifugally cast Ni alloy, the die was KPS6, and the inside was not particularly surface-treated. The screw surface roughness was Ra; 0.6 μm.

  The pellets were dried with a vacuum dryer (vacuum pressure 60 Pa) at 120 ° C. for about 5 hours. The moisture content of the pellet was measured and found to be 68 ppm. In addition, as a moisture meter, a Karl Fischer moisture measuring device CA-100 manufactured by Ear Instruments was used, and an automatic vaporizer VA-100 manufactured by Dia Instruments was used as a vaporizer. The sample pellet weight was 1.0 g. The measurement temperature is 280 ° C.

  The dried pellets were immediately supplied to an injection molding machine and injection molded under the following conditions to form test pieces.

≪Molding conditions≫
Mold temperature: 120 ° C
Resin temperature: 360 ° C
Injection pressure: 80 MPa
Injection speed: 100mm / sec
Cycle: 1 minute Test piece: width 5mm, length 300mm, thickness 4mm
Injection molding machine: Pre-plastic injection molding machine (TR100-EH manufactured by Sodick Plustech)
(Clamping force 1000KN)
Screw: Tool steel NPR1 (Fujikoshi) made by arc ion plating
A film of 2 μm of CrN was formed on the film, and then 2 μm of TiSiN and then CrN.
A film having a thickness of 2 μm and a TiSiN film of 2 μm on the outermost surface. surface
Roughness: Ra; 0.6 μm
Plunger: The same film is formed on the plunger surface. Inside the nozzle: Inside the nozzle is formed a film of 2 μm AlZrN single layer. Barrel: Centrifugal cast Ni alloy

  An oximeter was attached to the hopper, and the fitting member and the part with a gap were sealed with an O-ring or a sealant. Nitrogen gas was supplied from under the hopper, and the oxygen concentration in the hopper was set to 3% by volume.

  The obtained test piece was very clean and colorless and transparent, and had a hue comparable to that of an acrylic resin. About the obtained test piece, the total light transmittance (%) and yellowing degree (YI) were measured on condition of the following. The results are shown in Table 1.

  Furthermore, the obtained test piece was heated in a hot air circulating dryer at 120 ° C. for 2 hours to perform annealing treatment, and the total light transmittance (%) and yellowing degree (YI) were measured. The results are shown in Table 1.

<< Measurement conditions of total light transmittance (%) and yellowing degree (YI) >>
Using a spectrophotometer ("ASA-1 type" manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance (%) and YI of the molded test piece at a length of 300 mm were measured. The numerical value of the total light transmittance (%) showed a transmittance of 460 nm having a peak intensity in a white LED. In addition, although the transmittance | permeability is normally measured by 3 mm thickness, it measured by 300 mm so that the effect of this invention might be understood more.

[Example 2]
A test piece was produced in the same manner as in Example 1 except that the supply of nitrogen gas under the hopper of the extrusion molding machine for pellet forming was stopped, and the total light transmittance (% ) And yellowing degree (YI). The obtained molded product was very clean and colorless and transparent, and had a hue comparable to that of an acrylic resin. The results are shown in Table 1.

[Example 3]
The pellet was dried at 120 ° C. for 5 hours using a hot air circulating dryer. Thereby, a pellet having a water content of 128 ppm was obtained. A test piece was produced in the same manner as in Example 1 except that this pellet was used, and the total light transmittance (%) and the yellowing degree (YI) were measured for each test piece before and after the annealing treatment. The obtained molded product was very clean and colorless and transparent, and had a hue comparable to that of an acrylic resin. The results are shown in Table 1.

[Example 4]
A test piece was produced in the same manner as in Example 3 except that the supply of nitrogen gas under the hopper of the extrusion molding machine for pellet forming was stopped, and the total light transmittance (% ) And yellowing degree (YI). The results are shown in Table 1. The obtained molded product was very clean and colorless and transparent, and had a hue comparable to that of an acrylic resin.

[Examples 5 to 8]
Except having used the following as an injection molding machine, a test piece is manufactured similarly to Examples 1-4, and total light transmittance (%) and yellowing degree (YI) about each test piece before and behind annealing treatment. Was measured. The results are shown in Table 1. The obtained molded product was very clean and colorless and transparent, and had a hue comparable to that of an acrylic resin.
The fifth embodiment corresponds to the first embodiment, the sixth embodiment corresponds to the second embodiment, the seventh embodiment corresponds to the third embodiment, and the eighth embodiment corresponds to the fourth embodiment.

SE100DU made by Sumitomo Plastics Machinery (clamping force 1000 kN) Screw: CrN film of 2 μm was formed on the base material by arc ion plating method on tool steel NPR1 (manufactured by Fujikoshi), and then 2 μm of AlCrSiN film was formed. The surface roughness is Ra; 0.6 μm. Screw head surface, backflow prevention ring surface, sheet ring surface: 3 μm of CrSiN was formed by arc ion plating. Barrel: Centrifugal casting Co alloy Nozzle inside: Au was deposited in a thickness of 1 μm by arc ion plating.

[Comparative Example 1]
In Example 4, no film was provided on the screw (surface roughness Ra: 0.6 μm) of an extruder for molding resin material pellets. The water content of the resin pellets after hot air drying was 134 ppm.

  As the injection molding machine, the same one as in Example 4 was used except that a 5 μm thick TiN film was provided on the screw surface and no film was provided on the plunger surface and inside the nozzle.

  Except for these, test specimens were produced under the same conditions as in Example 4.

  Table 1 shows the results of measuring the total light transmittance (%) and yellowing degree (YI) of the test piece before the annealing treatment.

[Comparative Example 2]
A test piece was produced and measured in the same manner as in Comparative Example 1 except that the coating on the screw surface of the injection molding machine was TiCN. The results are shown in Table 1.

[Comparative Example 3]
A test piece was manufactured and measured in the same manner as in Comparative Example 1 except that the coating on the screw surface of the injection molding machine was CrN, and the results are shown in Table 1.

[Comparative Example 4]
Test pieces were produced and measured in the same manner as in Comparative Examples 1 to 3 except that the addition amount of the phosphorus compound was 0.01 parts by weight, and the results are shown in Table 1.

  Comparative example 4 corresponds to comparative example 1, comparative example 5 corresponds to comparative example 2, and comparative example 6 corresponds to comparative example 3.

  As is apparent from Table 1, the formation of a film having a high oxidation start temperature on the screw of the extruder and the screw of the injection molding machine significantly improves the total light transmittance (%) and the yellowing degree (YI). The

  As Table 1 shows, the higher the oxidation start temperature of the film, and the lower the moisture content of the resin material after drying, the more transparent polycarbonate resin excellent in total light transmittance (%) and yellowing degree (YI). Obtainable.

  Moreover, the transparency is further improved by performing the annealing treatment.

Claims (12)

In a molding apparatus of a polycarbonate resin molded body for melting and molding a polycarbonate resin composition,
An apparatus for molding a polycarbonate resin molded body, wherein a surface in contact with a molten polycarbonate resin composition is coated with a film having an oxidation start temperature in air of 700 ° C. or higher. The molding device is an injection molding machine or an extruder;
The contact surface with the molten polycarbonate resin is at least a part of a screw surface, a barrel inner surface, a plunger surface, a screw head surface, a backflow prevention ring surface, a sheet ring surface, a nozzle inner surface, a die inner surface, and a flow path of the molten polycarbonate resin. The molding apparatus according to claim 1, wherein:   3. The film according to claim 1, wherein the film is at least one film selected from the group consisting of Pt, Au, TiAlN, TiSiN, AlCrN, CrSiN, TiBN, AlCrSiN, AlZrN, AlZrSiN, and CrBN. The molding apparatus as described.   The apparatus for molding a polycarbonate resin molded body according to any one of claims 1 to 3, wherein an oxidation start temperature of the film in the atmosphere is 850 ° C or higher.   A method for molding a polycarbonate resin molded body, comprising molding a polycarbonate resin molded body using the molding apparatus according to any one of claims 1 to 4. The polycarbonate resin composition contains a polycarbonate resin and a phosphorus compound,
The proportion of the phosphorus compound in the resin material is 0.02 to 0.3 parts by weight with respect to 100 parts by weight of the polycarbonate resin,
The method for molding a polycarbonate resin molded article according to claim 5, wherein the polycarbonate resin composition has a water content of 130 ppm or less.   The method for molding a polycarbonate resin molded body according to claim 6, wherein the phosphorus compound is a phosphorus heat stabilizer.   The method for molding a translucent polycarbonate resin molded article according to claim 6 or 7, wherein the resin material has a water content of 100 ppm or less.   The method for molding a polycarbonate resin molded article according to any one of claims 6 to 8, wherein the polycarbonate resin composition is vacuum-dried. A method for molding a light-transmitting polycarbonate resin molded body in which the polycarbonate resin composition is stored in a hopper, and the resin is supplied from the hopper to an injection molding machine via a resin supply path. There,
The nitrogen gas is supplied under a hopper which is a connecting portion between the hopper and the resin supply path, and the oxygen concentration in the hopper is 0.2 to 5.0 vol%. The molding method of the polycarbonate resin molding of any one of Claims 1.   The method for molding a polycarbonate resin molded body according to any one of claims 5 to 10, wherein the injection molded molded body is heated and annealed.   A polycarbonate resin molded article molded by the method according to any one of claims 5 to 11.