JPH0592422A - Manufacture of molding material for optical molded product - Google Patents

Abstract

PURPOSE:To mold an optical molded product having few foreign matter, by a method wherein polycarbonate having essentially crystallizability is made substantially into fine power of an amorphous state where the melting point is hardly noticed, which is melted, extruded and made into pellets or a sheet. CONSTITUTION:In polycarbonate which is essentially crystallizable, the melting point is noticed by a differential scanning calorimeter when a solution of methylene chloride having a concentration of 13.0wt.% is made into boardlike body having thickness of 0.5mm by evaporating the methylene chloride by leaving the solution of the methylene chloride as it is under a room temperature. A solution of an organic solvent of the polycarbonate is loaded into hot water having a temperature of 70-100 deg.C for rapid removal of the solvent, through which the polycarbonate can be made into an amorphous state where the melting point is not noticed substantially by the foregoing method. This powdery and granular body is melted, extruded and made into pellets or a sheet, which is either made into an optical molded product by injection molding and extrusion molding or a molding material by cutting. With this construction, an increase of a foreign matter at the time of molding can be controlled drastically and a high-capacity optical molded product is obtained easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molding material for an optical molded article, more specifically a method for producing pellets and sheets suitable for molding optical disks, optical cards, optical fibers, lenses, retardation films and the like. Regarding

[0002]

2. Description of the Related Art Polycarbonate is used in optical discs, optical cards, optical fibers, lenses, retardation films and the like because it has excellent properties such as strength, heat resistance, light transmittance and moisture resistance.

Polycarbonate obtained from 2,2-bis (4-hydroxyphenyl) propane [commonly known as bisphenol A] is generally used for producing such a molded article, and usually powdery polycarbonate is melt-extruded. A method of forming into pellets and using the pellets to perform injection molding has been adopted. The problem at this time is
Foreign substances (including gel) in the obtained molded product. As a method for reducing such foreign matter, for example, JP-A-58-12
Japanese Patent No. 6119 proposes a method in which a polycarbonate powder blended with an antioxidant is melt-extruded into pellets, and the pellets are used to injection-mold an optical disk substrate. However, the polycarbonate obtained from bisphenol A is crystalline, and the thermal history of the step of heating and melting such crystalline powder and extruding it into pellets is large, and even if an antioxidant is added, the generation of foreign matter is still prevented. It is difficult to suppress it sufficiently.

As a method for improving this problem, JP-A-2-276040 eliminates the pelletizing step,
A method has been proposed in which the thermal decomposition of a resin is reduced and the mixture of gels and carbides is reduced by directly injection-molding a polycarbonate powder that does not undergo a heat history to produce a disk substrate. However, even with this method, there is a heat history in the molding process of the next step, it is still impossible to sufficiently suppress the generation of foreign matter, and in order to directly injection-mold an optical molded product from a granular material, it is necessary to bite it. There are other problems such as poor quality due to instability.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a molding material capable of producing an optical molded article containing few foreign matters.

The inventors of the present invention have found that ordinary polycarbonate powder and granules have a high melting temperature and a high melt viscosity, generate a large amount of heat when the screw is caught in the melt extruder, and further cause friction between the powder and granules at the extreme part. It is difficult to control the resin temperature due to large heat generation, etc., and it becomes high temperature and heat deterioration easily occurs,
In addition, the melting point also fluctuates due to fluctuations in the granulation conditions, and the internal tropical zone changes, so attention is paid to the fact that the heat-deteriorated substances adhering to the cylinder and screw are stripped off and mixed as foreign matter. As a result of diligently studying, when melt-molding using an ordinary crystallized polycarbonate powder granule, the foreign matter in the obtained molded product almost doubles, whereas this crystalline polycarbonate has substantially no melting point. When used as an amorphous powder or granules, it becomes easier to control the resin temperature during melt extrusion, and the foreign matter in the pellet obtained by melt extrusion and the foreign matter in the molded product obtained by injection molding using this pellet. The present invention has been completed by investigating that there is almost no increase. The foreign matter as used in the present invention refers to those which are not uniformly dissolved in polycarbonate such as metal powders, carbides and gels, nor are they dissolved in a solvent.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a molding material for an optical molded article, which is characterized in that a polycarbonate which is originally crystalline is melt-extruded as a powder or granular material in a substantially amorphous state to form a pellet or a sheet. Is a manufacturing method.

The polycarbonate targeted by the present invention is
The following general formula

[0009]

[Chemical 1]

[In the formula, X is a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms, -S-, -SO _2- , -SO-, -O-.
Or -CO-], and a polycarbonate obtained by reacting at least one dihydric phenol selected from the group consisting of dihydric phenol and 4,4'-dihydroxydiphenyl with phosgene, or terephthal as a copolymerization component of such a polycarbonate. A polyester carbonate using an aromatic dicarboxylic acid such as acid, isophthalic acid or naphthalene dicarboxylic acid, having a concentration of 13.0% by weight.
It is an inherently crystalline polycarbonate whose melting point is recognized by a differential scanning calorimeter when a methylene chloride solution is prepared and is allowed to stand at room temperature to evaporate methylene chloride into a plate having a thickness of 0.5 mm. A polycarbonate obtained by using bisphenol A as the dihydric phenol is particularly preferable. The degree of polymerization is not particularly limited, but is preferably in the range of 12,000 to 30,000 in terms of viscosity average molecular weight. Such polycarbonate powder and granules are obtained by reacting phosgene with an alkaline aqueous solution of the above dihydric phenol,
It is obtained by removing the solvent from the organic solvent solution of polycarbonate obtained by the polycondensation reaction in the presence of the organic solvent.

The crystalline polycarbonate powder granules are prepared by subjecting a solution of a polycarbonate obtained in a conventional method in an organic solvent to hot water at a temperature slightly higher than the boiling point of the solvent, as described in, for example, JP-B-45-9875. When the mixture is placed in and concentrated gelation treatment is carried out, the obtained powdery particles are crystallized and the melting point is recognized by a differential scanning calorimeter. For example, polycarbonate powder obtained from bisphenol A has a particle size of 230-
A melting point is observed at 260 ° C.

The polycarbonate powder or granular material used in the present invention is a powder or granular material which is made of the above-mentioned crystalline polycarbonate and is in an amorphous state in which the melting point is not substantially recognized by a differential scanning calorimeter. Such powdery particles are disclosed, for example, in JP-A-63-2.
As described in Japanese Patent No. 86436, it can be obtained by rapidly pouring an organic solvent solution of polycarbonate into hot water at high temperature to remove the solvent. The high temperature referred to here is 7
It is 0 to 100 ° C. Conventionally, powders and granules obtained by such a method are porous, have a small apparent specific gravity, and are not easy to handle, and thus have not been adopted.

The extruder used in the present invention may be any one, and the conditions usually adopted as the melt extrusion conditions are also arbitrarily adopted. Pellets obtained by melt extrusion are molded into optical molded articles such as optical disks, lenses, sheets, and optical fibers by injection molding, extrusion molding or the like. Further, the sheet is processed into an optical molded product such as an optical card or a retardation film, or is cut and used as a molding material for the optical molded product.

[0014]

EXAMPLES The present invention will be further described below with reference to examples. In addition,
The viscosity average molecular weight (M) was determined by measuring the specific viscosity (η _sp ) with an Oswald viscometer from a solution of 0.7 g of polycarbonate dissolved in 100 ml of methylene chloride at 20 ° C., and the following formula η _sp / C = [η] + K [ η] ² C [η] = 1.23 × 10 ⁻⁴ M ^0.83

[Where C is a concentration of 0.7 and K is a constant of 0.45]. The amount of foreign matter is 1000 g of methylene chloride for 100 g of powder, pellets and molded products.
It was dissolved in ml and the amount of foreign matter of 0.5 μm or more was measured with a foreign matter measuring instrument manufactured by HYAC Leuco. The melting point was measured with a differential scanning calorimeter (hereinafter abbreviated as DSC) manufactured by DuPont. The polycarbonate solutions used in Examples and Comparative Examples are bisphenol A caustic soda solution, methylene chloride,
A 15 wt% methylene chloride solution of polycarbonate obtained by reacting p-tert-butylphenol (molecular weight modifier) and phosgene by a conventional method. The apparatus used for granulation is the introduction of the polycarbonate solution into the upper part of the main body. The kneader has a pipe, a hot water introducing pipe, a solvent vapor extracting pipe, and a vapor introducing pipe at a lower portion, and has a volume of 200 liters.

[0016]

Example 1 40 kg of hot water at 75 ° C. was charged into the above kneader, and a 15 wt% methylene chloride solution of a polycarbonate having a viscosity average molecular weight of 16,000 was added from a polycarbonate solution inlet tube with stirring at a rate of 150 l / hr and steam. Steam of 120 ° C. was supplied from the inlet tube at a rate capable of maintaining the internal temperature at 75 ° C. to obtain 45 kg of polycarbonate powder granules. Then, the obtained powder and granules are crushed (hammer type)
Were pulverized to a particle size of 3 mm or less with a hot air dryer and dried at 140 ° C. for 8 hours. Figure 1 shows the DSC chart of the obtained granules.
It was shown to. As is clear from FIG. 1, no melting point was found in this powder or granular material.

Cylinder temperature of the dried powder was 25 with an extruder [VSK 30 mm vent type manufactured by Nakatani Machinery Co., Ltd.].
Extruded at 5 ° C. and cut into pellets. The pellets were dried at 120 ° C. for 8 hours with a hot air dryer, and then injection-molded with an injection molding machine [Japan Steel Co., Ltd. Anker-V17-65 type] at a molding temperature of 300 ° C., a mold temperature of 80 ° C., a diameter of 120 mm, and a thickness of 1.2 mm. The disk was molded, and the evaluation results are shown in Table 1.

[0018]

[Comparative Example 1] The temperature of the hot water charged in the kneader was 45 ° C,
The amount was 50 kg, and the mixture was pulverized and dried under the same conditions as in Example 1 except that the inner temperature of the kneader was maintained at 45 ° C. The DSC chart of the obtained powder and granules is shown in FIG. As is clear from FIG. 2, the melting point of this powdery material was 241 ° C.

The dried powdery material was extruded by an extruder at a cylinder temperature of 265 ° C. and cut to obtain pellets. The pellets are dried with a hot air dryer at 120 ° C. for 8 hours,
A disk having a diameter of 120 mm and a thickness of 1.2 mm was molded with an injection molding machine at a molding temperature of 300 ° C. and a mold temperature of 80 ° C., and the evaluation results are shown in Table 1.

[0020]

Example 2 40 kg of warm water of 80 ° C. was charged into the above kneader, and a 15% by weight methylene chloride solution of a polycarbonate having a viscosity average molecular weight of 26,000 was stirred at a rate of 150 liters / hr through a polycarbonate solution inlet tube with stirring and steam. Steam of 120 ° C. was supplied from the introduction tube at a rate capable of maintaining the internal temperature at 80 ° C. to obtain 45 kg of polycarbonate powder granules. Then, the obtained powder and granules were pulverized with a pulverizer to a particle size of 3 mm or less, and then dried with a hot air dryer at 140 ° C. for 8 hours. No melting point was found in the obtained powder or granules.

The dried powdery material was extruded by an extruder at a cylinder temperature of 285 ° C. and cut to obtain pellets. The pellets are dried with a hot air dryer at 120 ° C. for 8 hours,
Molding temperature 320 ℃, mold temperature 100 ℃ by injection molding machine
A disk having a diameter of 120 mm and a thickness of 1.2 mm was molded with the above, and the evaluation results are shown in Table 1.

[0022]

[Comparative Example 2] The temperature of the warm water charged in the kneader was 45 ° C,
The amount was 50 kg, and the mixture was pulverized and dried under the same conditions as in Example 2 except that the inner temperature of the kneader was maintained at 45 ° C. The melting point of the obtained powder and granules was 248 ° C.

The dried powder and granules were extruded by an extruder at a cylinder temperature of 295 ° C. and cut to obtain pellets. The pellets are dried with a hot air dryer at 120 ° C. for 8 hours,
Molding temperature 320 ℃, mold temperature 100 ℃ by injection molding machine
A disk having a diameter of 120 mm and a thickness of 1.2 mm was molded with the above, and the evaluation results are shown in Table 1.

[0024]

Example 3 40 kg of warm water at 80 ° C. was charged into the above kneader, and a 15% by weight methylene chloride solution of a polycarbonate having a viscosity average molecular weight of 26,000 was stirred at a rate of 150 liters / hr through a polycarbonate solution inlet tube and steam. Steam of 120 ° C. was supplied from the introduction tube at a rate capable of maintaining the internal temperature at 80 ° C. to obtain 45 kg of polycarbonate powder granules. Then, the obtained powder and granules were pulverized with a pulverizer to a particle size of 3 mm or less, and then dried with a hot air dryer at 140 ° C. for 8 hours. No melting point was found in the obtained powder or granules.

The dried powder and granules were extruded at a temperature of 305 ° C. by a single screw type melt extrusion sheet manufacturing machine having a diameter of 40 mm.
A sheet having a width of 200 mm and a thickness of 1.5 mm was manufactured, and the evaluation results are shown in Table 1.

[0026]

[Comparative Example 3] The temperature of the hot water charged in the kneader was 45 ° C,
The amount was 50 kg, and the mixture was pulverized and ground under the same conditions as in Example 3 except that the inner temperature of the kneader was maintained at 45 ° C. The melting point of the obtained powder and granules was 248 ° C.

The dried powder and granules were extruded at a extrusion temperature of 315 ° C. by a single screw type melt extrusion sheet manufacturing machine having a diameter of 40 mm.
A sheet having a width of 200 mm and a thickness of 1.5 mm was manufactured, and the evaluation results are shown in Table 1.

[0028]

[Table 1]

[0029]

Industrial Applicability According to the present invention, it is possible to remarkably suppress the increase of foreign matter at the time of molding, easily obtain a high-performance molded product with a small amount of foreign matter, and the industrial effect to be produced is exceptional. ..

[Brief description of drawings]

FIG. 1 is a DSC chart of the powder and granules obtained in Example 1.

2 is a DSC chart of the powder and granules obtained in Comparative Example 1. FIG.

[Procedure amendment]

[Submission date] October 6, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

The inventors of the present invention have found that ordinary polycarbonate powder and granules have a high melting temperature and a high melt viscosity, generate a large amount of heat when the screw is caught in the melt extruder, and further cause friction between the powder and granules at the extreme part. It is difficult to control the resin temperature due to large heat generation, etc., and it becomes high temperature and heat deterioration easily occurs,
In addition, the melting point also fluctuates due to fluctuations in the granulation conditions, and the internal heating element changes, so attention is paid to the fact that thermally deteriorated substances adhering to the cylinder and screw are stripped off and mixed as foreign matter. As a result of diligently studying, when melt-molding using an ordinary crystallized polycarbonate powder granule, the foreign matter in the obtained molded product almost doubles, whereas this crystalline polycarbonate has substantially no melting point. When used as an amorphous powder or granules, it becomes easier to control the resin temperature during melt extrusion, and the foreign matter in the pellet obtained by melt extrusion and the foreign matter in the molded product obtained by injection molding using this pellet. The present invention has been completed by investigating that there is almost no increase. The metal powder and foreign matter in the present invention, carbides, not uniformly dissolved in the gel and polycarbonate, we have one that does not dissolve in the solvent, the powder particles as the powder pellets granular
Refers to the body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Kikumoto 1-6-21 Nishishinbashi, Minato-ku, Tokyo Inside Teijin Kasei Co., Ltd.

Claims (1)

[Claims] 1. A method for producing a molding material for an optical molded article, which comprises melt-extruding an essentially crystalline polycarbonate as a substantially amorphous powder or granules into pellets or sheets. However, the term “crystalline polycarbonate” as used herein means that a methylene chloride solution having a concentration of 13.0% by weight is left at room temperature to evaporate methylene chloride and have a thickness of 0.
Polycarbonate whose melting point is recognized by a differential scanning calorimeter when formed into a plate of 5 mm, and polycarbonate powder particles in a substantially amorphous state are powders whose melting point is not substantially recognized by a differential scanning calorimeter. It is a grain.