JP2526943B2 - Manufacturing method of polycarbonate resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a method for producing a polycarbonate resin molding material with reduced dust, and in particular, simplifies the process by eliminating a drying step in which dust is significantly increased. At the same time, dust is reduced to provide a polycarbonate resin molding material suitable as an optical material.

[Prior Art] Conventionally, as a method for producing a molding material from a polycarbonate resin solution, a method in which a resin is separated from a solution, dried, and extrusion pelletized is used. As a method for separating from a resin solution, a method in which a good solvent solution of a resin or a resin solution obtained by adding a poor solution to the resin solution to such an extent that precipitation does not occur is concentrated to gel (“gel concentration method”; solvent evaporation gelation, Concentration method (a) which is a "warm water dropping method" in which the resin solution is dropped into warm water and the solvent is distilled off to form a gel.
And precipitation method (b), which is a method of dropping the resin solution into the poor solvent or dropping the poor solvent into the resin solution.

On the other hand, polycarbonate resin as an optical material,
The amount of dust should be as small as possible, and the residual solvent should be
Since it causes the deterioration of adhesion strength and corrosion of the recording film, it is usually necessary to set the content to 50 ppm or less.

However, in the above-mentioned conventional method, there are disadvantages such as the difficulty of removing the solvent by drying due to the kind of the resin gel obtained and the residual amount of the acceptable solvent, and the necessity of using a large-sized dryer. . Further, in the drying and extruding steps, since solid powder having a high degree of dryness is inevitably handled, it is difficult to avoid gelation of the polycarbonate resin, deterioration such as carbonization and abrasion of the equipment surface due to mechanical friction. It was difficult to suppress the increase in dust.

[Problems to be solved by the invention]

In order to solve the above problems, conventionally, a method and conditions for obtaining a wet powder that reduces the load of the drying step (for example, production of a wet powder by a combination of a hot water dropping method and slurry pulverization) are used. Adopted to control the shape and structure of the obtained wet powder to make it a resin powder (spherical, porous) that is relatively easy to dry and has minimal mechanical wear. Further, strictly select the model for drying and extrusion. However, it was difficult to completely control the increase in dust in the drying and extrusion processes, although it was handled by detailed control of drying and extrusion conditions.

[Means for solving problems]

Therefore, the present inventors have diligently studied a method for producing a polycarbonate resin molding material by a method of solving the above-mentioned problems and omitting the step of handling a dried solid powder and reducing the residual solvent. As a result, they have arrived at the present invention by finding a method of directly feeding a wet powder having a specific particle size range to an extruder, distilling off a residual solvent and water, and pelletizing.

That is, the present invention contains water 0.5 to 10.0 wt%, organic solvent 0.1 to 5.0 wt%, and in the particles when dried.
Wet powder of polycarbonate resin having particles of 80 mesh or less in an amount of 5% by weight or less and particles of 10 mesh or more in an amount of 5% by weight or less is directly supplied to an extruder with a vent and extruded while degassing, and residual organic solvent It is a method for producing a low dust polycarbonate resin molding material characterized by being 50 ppm or less, and in a preferred embodiment, the vent surface resin surface renewal frequency Rf represented by the following formula (1) of the vented extruder: Rf = A / V (1) where A: Vent resin surface renewal amount (cm ² / sec) V: Vent resin passing amount (cm ³⁾ Further, the wet powder is a polycarbonate resin selected from the group consisting of methylene chloride, which is a good solvent for polycarbonate resin, and n-heptane, n-hexane, cyclohexane, benzene, toluene, and xylene. And a good solvent / poor solvent ≦ 0.2 (weight ratio).

 The structure of the present invention will be described below.

First, the wet powder of the polycarbonate resin of the present invention contains 0.5 to 10.0% by weight of water and 0.1 to 5.0% by weight of an organic solvent as described above, and particles of 80 mesh or less in particles when dried are 5% by weight or less, Particles having a size of 10 mesh or more are 5% by weight or less, and more preferably the wet powder is methylene chloride and n- which are good solvents for polycarbonate resin.
Heptane, n-hexane, cyclohexane, benzene,
Toluene, consisting of a poor solvent of a polycarbonate resin selected from the group consisting of xylene, good solvent / poor solvent ≤ 0.
2 (weight ratio). If the water content of the wet powder is less than 0.5% by weight, the effect of removing volatile components such as an organic solvent is insufficient, and if it exceeds 10.0% by weight, it is not preferable because it bites into the extruder screw. Also, the smaller the amount of the organic solvent, the better, but it is substantially difficult to make it less than 0.1% by weight, and if it exceeds 5% by weight, the extruder must be very It is not preferable because it is necessary to increase the size, which is economically disadvantageous, and further, the weight ratio of the good solvent / non- or poor solvent in the organic solvent contained in the wet powder is within the above range of 0.2 or less. It is preferable in order to completely remove a good solvent such as methylene chloride. In addition, when this wet powder is dried,
If the amount of particles of mesh or less exceeds 5% by weight, dust is easily adsorbed and handling becomes difficult. If the amount of particles of 10 mesh or more exceeds 5% by weight, biting into the extruder screw becomes unstable, which is not preferable.

The above-mentioned wet powder of the polycarbonate resin of the present invention is preferably a solution prepared by adding a non-solvent or a poor solvent of the polycarbonate resin to a good solvent solution of the purified polycarbonate resin to such an extent that precipitation does not occur, and dropping the solution into warm water. The so-called "warm water dropping method" in which the solvent is distilled off while appropriately wet pulverizing,
Alternatively, it is produced by a "precipitation warm water treatment method" in which a wet powder containing a good solvent and a non- or poor solvent obtained by a usual precipitation method is treated in warm water, and the solvent is distilled off to perform appropriate wet pulverization.

Here, the polycarbonate resin is an aromatic homo- or co-polycarbonate resin using a normal bisphenol, further branched, a viscosity average molecular weight 13,000 such as a long-chain alkyl group introduced at the end. ~
30,000, a polycarbonate resin having a carbon-carbon unsaturated double bond or other graftable point as an end terminating agent or a comonomer in the method for producing these polycarbonate resins, and a product obtained by grafting styrene or the like on this, or polystyrene. It is possible to use any of those obtained by copolymerizing a phenolic hydroxyl group with other compounds having a graft polymerization initiation point of a polycarbonate resin, and grafting a polycarbonate resin thereto.

Examples of the solvent include halogenated hydrocarbons such as dichloromethane (= methylene chloride, methylene chloride), 1,1-dichloroethane, chlorobenzene and chlorotoluene as good solvents used in the polymerization reaction of the polycarbonate resin, and particularly methylene chloride. It is suitable.

Examples of the non-or poor solvent include n-heptane, n-hexane, cyclohexane, benzene, toluene and xylene, and n-heptane, n-hexane and cyclohexane are particularly preferable.

The purified polycarbonate resin solution is usually produced by separating the solvent solution from the polycarbonate resin polymerization solution, removing the catalyst, neutralizing, washing with water, concentrating, etc., and further removing dust by centrifugation or microfiltration. To be done. Fine "dust" in purified polycarbonate resin liquid
The smaller the value, the better.
Is preferably 1000 or less in 1 cc of the polycarbonate resin solution. The resin concentration is preferably 10 to 25% by weight, more preferably 10 to 20% by weight.

The amount of non- or poor solvent added to the resin solution in the warm water dropping method depends on the SP value of the polycarbonate resin and the non-solvent.
The difference in SP value, and is appropriately selected depending on the concentration of the polycarbonate resin solution, for example, among those exemplified above, when the concentration of the polycarbonate resin solution is 15 to 25 wt%, the difference in SP value is about 2.3. N-heptane is 0.15-0.5 times the volume of the resin solution, and the difference in SP value is about 1.55.
Is appropriately selected from the range of 0.3 to 0.6 times by volume for cyclohexane, and 0.5 to 0.8 times by volume for toluene having a difference in SP value of about 0.9. The homogeneous solution obtained above is usually 45-60
Gelled by dropping or spraying in water under stirring kept at a relatively low temperature side of ℃, then kept at a high temperature side of 80 ~ 100 ℃,
The solvent is distilled off to obtain a porous slurry of polycarbonate resin in water, and water is separated. When producing this water slurry, it is preferable to perform gelling particles while appropriately stirring and pulverizing with a wet pulverizer in order to extrude and distill off the solvent in the extruder more easily. is there. The aromatic polycarbonate powder granules separated and drained from the water slurry obtained as described above usually contain methylene chloride as a solvent and, in the case of using n-heptane as a non- or poor solvent, water and chloride. Methylene 0.1-0.3%,
It contains about 1-2% of n-heptane.

In the precipitation hot water treatment method, a solution of a purified polycarbonate resin in a good solvent is dropped into a non- or poor solvent, or a solution of a purified polycarbonate resin in a good solvent is dropped into a non- or poor solvent to form a precipitate. Then, this is separated to obtain a wet powder, and the wet powder is mixed with water in an amount of 5 times by weight or more with respect to the resin content in the wet powder and made into a hillary state. Less, and after being molded to a particle size in the case of dried in the above range, it is easily produced by separating and draining, also in the case of this method containing the same degree of organic solvent A wet powder is obtained. In addition, when the wet powder obtained by the above precipitation is treated with warm water to distill off the solvent and control the particle size, it is possible to appropriately apply washing or heat treatment with a non- or poor solvent of the polycarbonate resin in advance. is there.

The present invention, the wet powder described above as it is or a stabilizer, a mold release agent, and other additives to this wet powder are appropriately blended and supplied to an extruder with a vent, a resin temperature of 280 to 340 ° C.,
Preferably, in the range of 300 ~ 320 ℃, the vent portion under reduced pressure,
Preferably, the pressure is reduced to 10 Torr or less and the gas is vented and extruded to obtain pellets having a residual organic solvent content of 50 ppm or less.

Since the present invention removes the organic solvent at the same time as extrusion pelletization, it is preferable from the viewpoint of productivity that the solvent be distilled off from the vent section in a good manner. It is preferable to practically use a resin having a resin surface renewal frequency Rf of 150 or more in the vent portion represented by the following formula (1) of the machine.

Rf ＝ A / V ・ ・ ・ (1) where A: Vent resin surface renewal amount (cm ² / sec) V: Vent resin passing amount (cm ³ / sec) Vent portion in formula (1) Resin surface renewal amount (A, cm ² / sec)
Is the extruder screw diameter (D, cm), vent length (Lv, cm), screw rotation speed (N, rp)
m.) and the number of screws (Ns), and is represented by the following formula (2) where π is the circular constant.

A = (πD × N × Lv × Ns) / 60 (2) Also, the resin passage amount (V, cm ³ / sec) of the vent part is the resin discharge amount of the extruder (V ₁ , kg / hr) ) And the density (ρ, g / cm ³ ) of the polycarbonate, and the density is represented by the following formula (3) with ρ = 1.2.

V = V ₁ × 1000 / (60 × 60) / ρ = V ₁ /4.32 (3) Further, in the extruder of the present invention, extrusion is performed to prevent the polycarbonate resin from gelling and carbonizing. It is preferable that the material of the barrel, screw, etc. of the machine is one that has less gelation and carbonization, and that the entire surface is hard chrome plated or the like, and SKD steel or the one in which the SKD steel surface is nitrided is not preferable.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples and the like.

In addition,% and parts in Examples and the like are based on weight unless otherwise specified.

Example 1 and Comparative Example 1 Production of Polycarbonate Resin Molding Material. Polycarbonate resin solution produced by purifying methylene chloride solution of polycarbonate resin produced from bisphenol A to obtain a solution having a resin concentration of 20% and a viscosity average molecular weight of 1.5 × 10 ⁴ , and microfiltering this solution with a cartridge filter having a filtration accuracy of 0.2 μm. And

Micro-filtered n-heptane 40 was also added to this resin solution 200 with stirring and mixed uniformly, and then this solution was dropped into warm water under strong stirring for 10 minutes and pulverized with a wet pulverizer. Liquid temperature in the container during dropping is 40 ℃, internal pressure is 0.1kg / cm ² G
Maintained below.

After the completion of the dropping, the temperature was raised to 95 ° C. or higher, the remaining solvent was evaporated and distilled off for about 15 minutes, and the obtained polycarbonate resin water slurry was taken out, filtered and drained. When the wet powder of the obtained polycarbonate resin is dried, the particle size distribution is 3.7% for 80 mesh or less and 4.0 for 10 mesh or more.
%, And the amounts of water, n-heptane, and methylene chloride in the wet powder were as shown in Table 1 below. In addition, a wet powder was obtained in the same manner as above except that the treatment time for distilling off the residual solvent after the dropping was 30 minutes.

Each of the wet powders obtained above was supplied to an extruder with a vent in a closed system in which dust was not mixed, and the solvent was distilled off together with the extrusion. The extruder is twin screw, screw diameter (D) 65mm, total length L / D = 30, vent part Lv / D = 4 (vent width 4cm, center of 2 screws), the maximum temperature of resin 300 ℃, vent pressure An example with 9 Torr is shown in Table 1.

Optical disk manufacturing and reliability evaluation. Using the above pellets, injection molding was carried out to obtain an optical disk substrate for data files having a spiral groove on one side and a thickness of 1.2 mm and a diameter of 130 mm.

A Te-Fe-Co recording film was vapor-deposited on this substrate in an amount of 300 to 500 liters, and a photo-curing acrylic resin was coated on the recording film and cured by ultraviolet rays.

The number of defects of 30 μm or more along the circumference of this optical disk was measured on the entire disk surface, and the same measurement was performed by leaving this disk at 80 ° C, 90% RH, 850hrs for the same measurement. The results are shown in Table 1.

For the inspection of the number of flaws on the disc, an automatic flaw inspection device I type manufactured by JEOL Ltd. was used.

Example 2 In Example 1, the polycarbonate resin liquid obtained by microfiltration and purification used in the production of wet powder was mixed with n-heptane, and the treatment time for distilling off the residual solvent after the completion of the dropping was changed. A wet powder was obtained in the same manner except that the time was 2 hours. Particle size distribution when the obtained wet powder of polycarbonate resin is dried is 80 mesh or less is 1.5
%, 10 mesh or less was 4.6%, the water content in the wet powder was 4.8%, and methylene chloride was 180 ppm.

Discharge rate of 100kg / H
r, 80kg / Hr, 50kg / Hr, but with the same result
The results are shown in Table-1.

Comparative Example 1 A polycarbonate resin wet powder obtained in the same manner as in Example 2 was dried in a batch type dryer at a temperature of 140 ° C. for 4 hours and 6 hours, and introduced into the same extruder as in Example 2 in a closed system. Table 2 shows the results of the same test conducted on pellets.

Incidentally, most of the defect numbers (* 3) in Table 2-2 are those in which gelation during drying, generation of carbides and generation of dust due to abrasion were observed.

Example 3 and Comparative Example 2 A polycarbonate resin wet powder obtained in the same manner as in Test No. 1 of Example 1 was used, and the screw rotation speed and discharge rate of the extruder were changed as shown in Table 3 in the same manner. The results obtained are shown in Table 3.

Example 4 A solution obtained by stirring and mixing n-heptane 40 with a microfiltration and purification liquid 200 of a polycarbonate resin obtained in the same manner as in Example 1 was dropped into n-heptane kept at 25 ° C. under stirring. After completion of the dropping, this was filtered to obtain a powder.

This powder was mixed with water at 25 ° C., the temperature was raised to 95 ° C. or higher to evaporate and distill off the organic solvent, and the powder was taken out, filtered and drained to obtain a wet powder. When the wet powder is dried, the particle size distribution is 80% or less 3.6%, 10 mesh or more 4.8%, the moisture content of the wet powder 4.9%, n-heptane 1,000 pp
m and methylene chloride were 220 ppm.

The same results as in Example 2 except that this wet powder was used are shown in Table 4-1.

Comparative Example 3 The procedure of Comparative Example 1 was repeated except that the polycarbonate resin wet powder obtained in the same manner as in Example 4 was used. The results are shown in Table 4-2.

[Operations and effects of the invention] As described above, the polycarbonate resin molding material in which the drying step of the present invention is omitted, the increase in dust is also in the pellets obtained with respect to the dust number of the raw material wet powder when the dryer is used. Despite the fact that the number of dusts has increased by 5 to 10 times or more, it is almost nonexistent, and the residual organic solvent sufficiently satisfies 50ppm or less, so the number of defects in the molded disc is small, etc. The characteristics of (1) are improved, and it can be used very suitably as an optical material.

In addition, even in the manufacturing process, there is no drying step using a large-sized dryer that is usually required to remove the residual solvent, so the process is simple and rational, and it is important in terms of industrial practicality. It has great significance.

Claims (3)

(57) [Claims] 1. Water 0.5 to 10.0% by weight, organic solvent 0.1 to 5.0
Wet powder of polycarbonate resin containing 5% by weight or less of particles of 80 mesh or less in dried particles and 5% by weight or less of particles of 10 mesh or less is supplied as it is to an extruder with a vent. And extruding while degassing to make the residual organic solvent 50ppm or less. 2. The method for producing a polycarbonate resin molding material according to claim 1, wherein a resin surface renewal frequency Rf of the vent portion represented by the following formula (1) of the vented extruder is 150 or more. Rf ＝ A / V ・ ・ ・ (1) However, A: Vent resin surface renewal amount (cm ² / sec) V: Vent resin passing amount (cm ³ / sec) 3. The organic solvent in the wet powder is methylene chloride and n-heptane, which are good solvents for polycarbonate resin, and n.
-Hexane, cyclohexane, benzene, toluene, consisting of a poor solvent of a polycarbonate resin selected from the group consisting of xylene, good solvent / poor solvent ≤ 0.2 (weight ratio)
The method for producing a polycarbonate resin molding material according to claim 1 or 2, wherein