JP2018183933A - Method for manufacturing polycarbonate resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a polycarbonate resin composition capable of manufacturing a polycarbonate resin composition with small dispersibility of fluororesin without operation trouble in an extruder, and capable of continuously and stably supplying a fluororesin over a long term.SOLUTION: Provided is a method for manufacturing a polycarbonate resin composition in which 80-97 pts.mass of a polycarbonate resin is fed from a main hopper using a twin screw extruder having a main hopper, a side feeder, and a vent port, and 20-3 pts.mass of a fluororesin without fibril formation capacity is fed from the side feeder to be melted and kneaded. At least one vent port is provided at a joining portion of the side feeder and the twin screw extruder or an upper stream side thereof, and the specific energy is in the range of 0.05-0.15 kWh/kg.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a polycarbonate resin composition, and more particularly to a method for producing a polycarbonate resin composition containing a fluororesin with an extruder.

  A fluororesin is added to the polycarbonate resin, and a fluororesin having a fibril forming ability is blended to prevent dripping of the resin during combustion. Further, blending a fluororesin having no fibril forming ability with a polycarbonate resin is also performed.

  Among these, as a method for producing a polycarbonate resin composition for preventing drip, in Patent Document 1, an aqueous dispersion of a granular polycarbonate resin (A-1) and a fluororesin having a fibril-forming ability is formed into a pellet form. In the presence of the polycarbonate resin (A-2), a polycarbonate resin composition (A-3) is blended with the resulting mixture, and a method for producing a polycarbonate resin composition is described.

  On the other hand, it is never easy to sufficiently disperse a fluororesin having no fibril-forming ability as small particles in a polycarbonate resin, and it is difficult to obtain uniform dispersion by melt kneading with a normal extruder, and it is long. It is difficult to operate continuously and stably over time.

It is well known that when a powdered additive is blended with a thermoplastic resin, a biaxial extruder having a side feeder is used to supply the additive from the side feeder to highly disperse the additive. .
For example, Patent Document 2 describes a method of extruding a powdery resin or a filler-like reinforcing material into a pellet-like resin with a twin screw extruder including a screw composed of a specific screw element. Patent Document 3 describes a method of extruding a powdery reinforcing material such as calcium carbonate into a thermoplastic resin with a twin screw extruder having a specific screw element configuration. Further, in Patent Document 4, a first kneading zone of a screw composed of a specific kneading disk, etc., with a reinforcing material such as mica, talc, and glass fiber in a thermoplastic resin such as liquid crystalline polyester (LCP), a specific kneading A method of manufacturing in a twin-screw extruder having a second kneading zone with a disc or a specific mixing screw is described.

  Then, the present inventor previously melted and kneaded in Patent Document 5 using a mesh type co-rotating twin screw extruder and using a screw made of a specific screw element for polycarbonate resin supplied from a main hopper. Then, a method has been proposed in which the fluororesin having no fibril-forming ability is side-fed and kneaded to thereby reduce the particle size of the fluororesin. This method is an effective method for finely dispersing a fluororesin that does not have fibril-forming ability, but it sometimes causes a problem in the feed stability of the fluororesin, resulting in an operation trouble.

JP 2011-084661 A Japanese Patent Laid-Open No. 10-180840 Japanese Patent Laid-Open No. 10-180841 JP2015-110329A JP, 2006-108526, A

  The present invention was devised in view of the above-mentioned problems. There is no operation trouble in the extruder, and the fluororesin can be supplied continuously and stably over a long period of time. Moreover, the dispersibility of the fluororesin in the polycarbonate resin An object of the present invention is to provide an excellent manufacturing method.

  As a result of diligent study to solve the above problems, the present inventor supplied a polycarbonate resin from a main hopper using a twin-screw extruder, a fluororesin having no fibril forming ability from a side feeder, and a side feeder. Dispersion of fluororesin by providing at least one vent port at the joint of the twin screw extruder or upstream thereof, and the specific energy during kneading to be in the range of 0.05 to 0.15 kW · Hr / kg It has been found that a polycarbonate resin composition having a small particle diameter can be stably produced with good productivity.

Polycarbonate resin supplied from the main hopper is polycondensed in a polycarbonate production plant, dried through a solidification process, and packed in paper bags and flexible container bags. The moisture content depends on the season, weather, storage conditions, and surrounding environment. May vary up to about 0.04 to 0.40% by weight.
Since production equipment using an extruder handles a large amount of polycarbonate resin, it is the current situation that moisture is not strictly controlled and supplied. When polycarbonate resin with a high moisture content is supplied, the moisture is volatilized in the extruder. As a result, the trouble that the fluororesin is not stably supplied often occurs. That is, in order to stably side feed the fluororesin, it is necessary to supply the fluororesin after the moisture content of the polycarbonate resin is set to a predetermined value or less in advance, and therefore, at least one of the side feed port coupling portion or the upstream side thereof is required. In order to improve the dispersibility of the fluororesin in the polycarbonate resin by providing two vent ports, the above-mentioned problem is achieved by setting the specific energy within the above range.
The present invention relates to the following method for producing a polycarbonate resin composition.

[1] Using a twin screw extruder having a main hopper, a side feeder, and a vent port, 80 to 97 parts by mass of polycarbonate resin is supplied from the main hopper, and the fluororesin 20 to 3 having no fibril forming ability from the side feeder A method for producing a polycarbonate resin composition in which a mass part is supplied and melt kneaded, wherein at least one vent port is provided at a joint part of a side feeder and a twin-screw extruder or upstream thereof, and a specific energy is 0.05. It is the range of -0.15kW * Hr / kg, The manufacturing method of the polycarbonate resin composition characterized by the above-mentioned.
[2] The method for producing a polycarbonate resin composition according to [1], wherein the vent port is an open vent or a vacuum vent.
[3] A full flight screw, a square flight screw, and a single wide-width flight, wherein the screw of the fluororesin transport section has a ratio L / D of a screw lead length L to a screw diameter D of 0.5 to 2.0. A process for producing a polycarbonate resin composition according to the above [1] or [2], comprising a screw element selected from screws.
[4] A seal ring or reverse lead in which the screw configuration between the vent port and the fluororesin supply port is such that the ratio L / D of the screw lead length L to the screw diameter D is 0.3 to 2.0. The manufacturing method of the polycarbonate resin composition in any one of said [1]-[3] containing a flight screw.

  According to the method for producing a polycarbonate resin composition of the present invention, a polycarbonate resin composition having a low dispersibility of a fluororesin can be supplied continuously and stably over a long period of time without trouble in an extruder. Is possible.

It is explanatory drawing which shows the outline of the twin-screw extruder used for the manufacturing method of this invention. It is explanatory drawing of the twin-screw extruder used by the Example and the comparative example.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the embodiments and examples described below, and may be arbitrarily selected without departing from the scope of the present invention. You can change it to

  The method for producing the polycarbonate resin composition of the present invention is to supply 80 to 97 parts by mass of polycarbonate resin from the main hopper using a twin screw extruder having a main hopper, a side feeder and a vent port, and form a fibril from the side feeder. Is a method for producing a polycarbonate resin composition in which 20 to 3 parts by mass of a fluororesin having no content is supplied and melt-kneaded, and at least one vent port is provided at the joint of the side feeder and the twin screw extruder or at the upstream side thereof And the specific energy is in the range of 0.05 to 0.15 kW · Hr / kg.

[Polycarbonate resin]
Examples of the polycarbonate resin include an aromatic polycarbonate resin, an aliphatic polycarbonate resin, and an aromatic-aliphatic polycarbonate resin, preferably an aromatic polycarbonate resin. Specifically, an aromatic dihydroxy compound is converted to phosgene or carbonic acid. A thermoplastic aromatic polycarbonate polymer or copolymer obtained by reacting with a diester is used.

  Aromatic dihydroxy compounds include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), tetramethylbisphenol A, α, α'-bis (4-hydroxyphenyl) -p-diisopropylbenzene, hydroquinone, resorcinol 4,4′-dihydroxydiphenyl and the like. Further, in order to improve flame retardancy, a compound in which one or more tetraalkylphosphonium sulfonates are bonded to the aromatic dihydroxy compound described above, a polymer having both ends phenolic OH groups having a siloxane structure, or an oligomer thereof is used. Also good.

  Preferred examples of the polycarbonate resin include 2,2-bis (4-hydroxyphenyl) propane as a dihydroxy compound or a polycarbonate resin using 2,2-bis (4-hydroxyphenyl) propane in combination with another aromatic dihydroxy compound. Can be mentioned.

  The polycarbonate resin may be a homopolymer composed of one type of repeating unit or a copolymer having two or more types of repeating units. At this time, the copolymer can be selected from various copolymerization forms such as a random copolymer and a block copolymer.

The molecular weight of the polycarbonate resin is not limited, but the viscosity average molecular weight (Mv) is usually about 10,000 to 100,000, preferably about 12,000 to 35,000. By setting the viscosity average molecular weight to be equal to or higher than the lower limit of the above range, the mechanical strength of the polycarbonate resin composition can be further improved, which is more preferable when used for applications requiring high mechanical strength. On the other hand, by setting the viscosity average molecular weight to be equal to or lower than the upper limit of the above range, it is possible to suppress and improve the fluidity of the polycarbonate resin composition, and it is possible to easily perform thin-wall molding by improving molding processability.
Two or more types of polycarbonate resins having different viscosity average molecular weights may be mixed and used, and in this case, a polycarbonate resin having a viscosity average molecular weight outside the above-mentioned preferred range may be mixed.

In the present invention, the viscosity average molecular weight (Mv) of the polycarbonate resin is determined by measuring the viscosity of the methylene chloride solution of the polycarbonate resin at 20 ° C. using an Ubbelohde viscometer, and determining the intrinsic viscosity ([η]). It is a value calculated from the following Schnell viscosity equation.
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83

  The method for producing the polycarbonate resin is not particularly limited, and a polycarbonate resin produced by any of the phosgene method (interfacial polymerization method) and the melting method (transesterification method) can also be used. Moreover, the polycarbonate resin which performed the post-process which adjusts the amount of terminal OH groups to the polycarbonate resin manufactured by the melting method is also preferable.

  The polycarbonate resin may contain a polycarbonate oligomer. The viscosity average molecular weight [Mv] of this polycarbonate oligomer is usually 1,500 or more, preferably 2,000 or more, and usually 9,500 or less, preferably 9,000 or less. Furthermore, the polycarbonate ligomer contained is preferably 30% by mass or less of the polycarbonate resin (including the polycarbonate oligomer).

  The polycarbonate resin can be used not only as a virgin raw material but also as an aromatic polycarbonate resin recycled from a used product, that is, a so-called material recycled aromatic polycarbonate resin. Used products include optical recording media such as optical disks, light guide plates, automobile window glass and automobile headlamp lenses, vehicle transparent members such as windshields, containers such as water bottles, glasses lenses, soundproof walls and glass windows, waves A building member such as a plate is preferred. In addition, as the recycled polycarbonate resin, non-conforming product, pulverized product obtained from sprue or runner, or pellets obtained by melting them can be used.

[Fluoropolymer without fibril-forming ability]
The fluororesin used in the method for producing the polycarbonate resin composition of the present invention is a fluororesin having no fibril forming ability. Here, “fibril forming ability” means that resins tend to be bonded and become fibrous due to an external action such as shearing force. A measure of whether or not the fluororesin has “no fibril-forming ability” can be evaluated by specific melt viscosity, and the specific melt viscosity at 380 ° C. (ASTM 1238-52T) is 1 × 10 ⁷ poises or less. Furthermore, it is 1 × 10 ⁶ poises or less, and its lower limit is usually 5 × 10 ² poises.
A fluororesin that does not have fibril-forming ability does not form fibrils during melt kneading or molding, has excellent slidability, and can be well dispersed with a small dispersed particle size.

  As the fluororesin having no fibril forming ability, polytetrafluoroethylene is particularly preferable. Fluorine-containing olefins such as hexafluoropropylene, chlorotrifluoroethylene, fluoroalkylethylene and perfluoroalkyl vinyl ether, perfluoroalkyl (meth) acrylate, etc. as copolymerization components as long as they do not have the ability to form fibrils of polytetrafluoroethylene The fluorine-containing alkyl (meth) acrylate can be used. The content of such a copolymer component is preferably 10% by mass or less with respect to tetrafluoroethylene in polytetrafluoroethylene.

  The fluororesin having no fibril forming ability preferably has an average particle size of 1 to 20 μm, more preferably 10 μm or less, as a raw material before melt kneading.

Content of the fluororesin which does not have a fibril formation ability is 3-20 mass parts on the basis of a total of 100 mass parts of polycarbonate resin and a fluororesin. When the content is less than 3 parts by mass, sufficient slidability as a molded product is hardly exhibited, and when it is too small, the supply stability and dispersibility in the extruder are deteriorated, which is not preferable. On the other hand, if it exceeds 20 parts by mass, there is no problem in quality, but it is not preferable because it is disadvantageous in cost. The preferable content of the fluororesin having no fibril forming ability is 5 parts by mass or more, and preferably 15 parts by mass or less.
Moreover, the fluororesin which does not have a fibril formation ability may be supplied alone or in combination of two or more kinds, or may be supplied after being mixed with other resins, additives and the like.

[Production of polycarbonate resin composition]
The extruder used in the present invention is a twin screw extruder with a vent, and is generally used to obtain a pellet-shaped resin composition, but the twin screw extruder in the present invention is limited to this. Instead, it may be a sheet or film. Examples include the ZSK series manufactured by Coperion, the TEM series manufactured by Toshiba Machine Co., and the TEX series manufactured by Nippon Steel Works. In addition, the twin screw extruder of the present invention uses a twin screw extruder that has a higher shear energy to the resin than a single screw. A twin-screw extruder is usually a rotary drive consisting of a hopper material supply port, a temperature-adjustable cylinder, two screws rotatably arranged in the cylinder, a motor for rotating the two screws, and a speed reducer. It consists of a mechanism and a die attached to the tip of the extruder. The screw of the extruder used in the present invention can use both the same direction and the opposite direction of rotation, but is preferably a same direction twin screw.

Furthermore, the twin-screw extruder in the present invention, the _{L TL / D TL (L TL} = extruder screw _{length, D TL} = extruder screw diameter) is preferably from 30 to 80. If L _TL / D _TL is less than 30, it is difficult to obtain a desired screw configuration, and if L _TL / D _TL exceeds 80, it is not preferable because the residence time of the resin becomes long and decomposition degradation of the resin easily proceeds.

FIG. 1 is an explanatory diagram showing an outline of an example of a twin-screw extruder used in the production method of the present invention.
In the figure, 1 is a twin screw extruder, 2 is a main hopper, 3 is a side feed supply port, 4 and 5 are vent ports, and 6 and 7 are feeders.

  The polycarbonate resin is supplied from the main hopper 2 by the feeder 6, and the fluororesin having no fibril forming ability is supplied from the side feed supply port 3 by the side feeder 7. Then, at least one vent port 4 is provided at the joint portion of the side feed supply port 3 and the twin screw extruder 1 or on the upstream side thereof. If there is no vent port 4 in such a position, the moisture contained in the polycarbonate resin cannot be removed, and the stability of the side feed of the fluororesin is lowered. By providing a vent port 4 at the joint of the side feed supply port 3 or upstream thereof, moisture is vented after the polycarbonate resin is supplied, transported and kneaded, and the moisture content of the polycarbonate resin is kept below a certain level. The side feed of the fluororesin from the port 3 can be performed stably.

The polycarbonate resin supplied from the main hopper into the extruder is conveyed, preheated by a screw, kneaded and melted.
Hereinafter, description will be made with reference to a specific example of the screw configuration of FIG.
In FIG. 2, Z1 is a polycarbonate resin supply / conveyance / preheating zone, Z2 is a polycarbonate resin melting zone, Z3 is a fluororesin supply / conveyance / kneading zone, Z4 is a devolatilization / extrusion zone, and 2 is a polycarbonate resin supply port. (Main hopper) 3 is a side feed supply port, 4 and 5 are vacuum vent ports. In FIG. 2 (A), 3 + 4 indicates that the side feed supply port also serves as an open vent, and in FIGS. 2 (B) and (C), 3X indicates the side feed supply port. This indicates that the vent port is closed, but the vent port is closed. Further, C1 to C10 in FIG. 2 are numbers given for each area of the cylinder portion, and the numbers increase as going from the main hopper side to the tip direction.

  The polycarbonate resin supplied from the polycarbonate resin supply port 2 is conveyed, heated and kneaded by a screw in the polycarbonate resin supply / conveyance / preheating zone Z1. In the middle of the screw in the zone Z1, it is preferable that a kneading part constituted by a plurality of kneading disks is formed. The screw structure is preferably composed of a combination of two or more elements selected from a forward kneading disk, a reverse kneading disk, and an orthogonal kneading disk.

The progressive kneading disc element is also called R kneading (hereinafter also referred to as R), and usually has two or more blades, and the blade twist angle θ is preferably 10 degrees to 75 degrees. By setting the blades so as to be shifted by a predetermined angle in this way, a pseudo screw structure is formed, and a strong shearing force is applied while the polycarbonate resin is fed in the feeding direction, thereby providing a zone for kneading.
The reverse feed kneading disc element is also called L kneading (hereinafter also referred to as L), and usually has two or more blades and a twist angle θ of the blades of −10 degrees to −75 degrees. It is preferable. The reverse feed kneading disc element is an element with a boosting ability that works in the direction of blocking the sent resin or returning the sent resin, and is provided on the downstream side of the element that promotes kneading. Is used to exert a strong kneading effect.
The orthogonal kneading disc element is also called N kneading (hereinafter also referred to as N), and usually has two or more blades, and the twist angle θ of the blades is 75 degrees to 105 degrees. Since the blades are installed approximately 90 degrees apart, the force to send out the resin is weak, but the kneading force is strong.

  The screw configuration for kneading in the polycarbonate resin melting zone Z2 following the zone Z1 is preferably configured by a combination of two or more elements, with the element that promotes kneading on the upstream side and the element having a boosting capability on the downstream side. It is preferable to arrange. Therefore, in the polycarbonate resin melting zone Z2, it is preferable to arrange two or more kinds selected from R, N and L from the upstream side in the order of R → N → L, and a plurality of R, N and L are arranged. It is also preferable.

  After the polycarbonate resin is melted in the above-described zone Z2, a fluororesin having no fibril forming ability is supplied from the side feed supply port 3.

  At least one vent port 4 is provided at the connecting portion of the side feed supply port 3 and the twin screw extruder 1 or upstream thereof. If there is no vent port at such a position, it becomes impossible to remove the moisture contained in the polycarbonate resin, and the side feed stability of the fluororesin is lowered. A vent port 4 is provided at the joint of the side feed supply port 3 or upstream thereof, and after supply, transport and kneading of the polycarbonate resin, moisture is vented to keep the moisture content of the polycarbonate resin below a certain level. Side feed the fluororesin.

  The direction of the vent may be either an upward top vent or a lateral side vent, but is preferably a top vent. Further, either an open vent or a vacuum vent may be used, but when a vacuum vent is used, a seal ring or a vent between the vent port 4 and the fluororesin supply port 3 is used in order to prevent venting of the fluororesin described later. A reverse lead flight screw is preferably provided. In this case, the degree of vacuum is preferably 10 mmHg to 760 mmHg, and more preferably 20 mmHg to 500 mmHg. If the degree of vacuum is too large, the volatilization tends to be difficult. On the other hand, it may be smaller than this range, but the lower limit of this range is sufficient because of problems on the apparatus.

  The screw configuration between the vent port 4 and the fluororesin supply port 3 preferably includes a seal ring or a reverse lead flight screw, and such a screw configuration is effective in preventing venting of the fluororesin, The L / D (ratio between the screw lead length L and the screw diameter D) is preferably 0.3 to 2.0. If L / D is less than 0.3, the pressure tends to rise too much, and if L / D exceeds 2.0, production becomes difficult.

  The vent port 4 is provided at the connecting portion of the side feed supply port 3 and the twin screw extruder 1 or at the upstream side thereof. As shown in FIG. 2A, 3 + 4, the side feed supply port 3 is open vent 4. A mode in which both are combined is also preferable. Further, as shown in FIG. 2B, a side feed supply port and a vent port that can be used together are provided, the vent port is closed (3X in the figure), and the vent port 4 may be provided upstream thereof. .

Although the supply of the fluororesin having no fibril forming ability is performed by a side feeder, various side feeders such as a screw feeder and a vibratory feeder can be used as the side feeder, but preferably a screw feeder, particularly 2 It is preferable to use a method of supplying the cylinder with a screw.
In addition, it is preferable to supply the fluororesin to the side feeder at a low speed so as not to cause reaggregation of the fluororesins as much as possible.

The fluororesin not having fibril forming ability supplied from the side feed supply port 3 is melted while being dispersed in the fluororesin supply / conveyance / kneading zone Z3 while joining with the vented molten polycarbonate resin. The polycarbonate resin is kneaded with a screw.
The screw of the fluororesin transport section in the zone Z3 is a full flight screw, a square flight screw or a single wide flight having a ratio L / D of the screw lead length L to the screw diameter D of 0.5 to 2.0. It is preferable that the screw element is selected from screws. When L / D is less than 0.5, the carrying ability is lowered, and when L / D exceeds 2.0, the dispersibility of the fluororesin tends to be deteriorated.
The screw lead length L is defined as the distance that the material travels in the axial direction when the screw rotates once, assuming that the material is filled in 100% screw grooves.

  The screw of the kneading zone in the zone Z3 is an element selected from a forward feed kneading disc (R), a reverse feed kneading disc (L), an orthogonal kneading disc, a forward feed notch type mixing screw, and a reverse feed notch type mixing screw. It is preferable that it is comprised.

A progressive feed notch type mixing screw (hereinafter also referred to as FMS) is a forward feed mixing screw element in which a screw peak (flight part) is cut away. The number of flights may be two or one, and the number of notches is preferably 5 to 15 per screw lead. Also included is a gear type mixing screw.
A reverse feed notch type mixing screw (hereinafter also referred to as BMS) is a reverse feed mixing screw element in which a crest (flight part) of a screw is cut out. The number of flights may be two or one, and the number of notches is preferably 5 to 15 per screw lead. Also included is a gear type mixing screw.

  As for the screw configuration of the kneading zone in zone Z3, one of these elements may be used alone, or two or more of them may be used in combination, and each element may be used alone or in combination of two or more. The R, N, or L is preferably located upstream of the kneading zone, and the FMS or BMS is preferably located downstream.

  After the zone Z3, it is sent to the devolatilization / extrusion zone Z4, where a vent port 5 is usually provided to sufficiently vent moisture and devolatilizing components. The vent port 5 is usually preferably a vacuum vent.

  Thereafter, the polycarbonate resin composition in a molten state is extruded in a strand form from an extrusion die at the tip of the extruder. The extruded molten resin in the polycarbonate resin composition is cooled and cut into pellets.

In the method of the present invention, the kneading is performed in a range of specific energy of 0.05 to 0.15 kW · Hr / kg. The specific energy is defined as a value expressed per unit extrusion mass of work performed on the raw material by an extruder, and is represented by power consumption (kW) required for kneading per unit extrusion mass (kg / h). When the specific energy is less than 0.05 kWh / kg, the resin composition is not sufficiently kneaded. On the other hand, when the specific energy is greater than 0.15 kWh / kg, the shear heat generation during melt-kneading becomes too large, and the resin temperature is extremely high. As a result, the coloration and mechanical properties of the resin composition deteriorate, which is not preferable.
The specific energy can be adjusted by the ratio L _TL / D of the entire length L _TL of the extruder screw and the diameter of the screw, or the discharge amount (Q / N) per screw rotation.

  The kneading is preferably carried out with a screw so that the resin temperature is 260 to 320 ° C. In order to achieve such a resin temperature, it is possible to adjust the discharge amount and screw rotation speed as appropriate, or to set the cylinder set temperature low. By setting the resin temperature to a resin temperature of 260 to 320 ° C., a polycarbonate resin composition having a small dispersed particle diameter of the fluororesin and a good dispersed state can be stably produced. The resin temperature is preferably 280 to 320 ° C, more preferably 290 to 315 ° C, and further preferably 300 to 310 ° C. If the resin temperature is less than 260 ° C., unmelted resin is generated or an excessive load is applied to the extruder motor. On the other hand, when the temperature exceeds 320 ° C., the dispersed particle size of the fluororesin becomes large, which is not preferable.

  In the method for producing a polycarbonate resin composition of the present invention, as long as desired physical properties are not significantly impaired, if necessary, other components may be contained in addition to the polycarbonate resin and the fluororesin having no fibril-forming ability. Good. Examples of other components include resins other than polycarbonate resins and various resin additives. In addition, 1 type may contain other components and 2 or more types may contain them by arbitrary combinations and a ratio.

Other resins Examples of other resins include thermoplastic polyester resins such as polyethylene terephthalate resin, polytrimethylene terephthalate, and polybutylene terephthalate resin; polystyrene resin, high-impact polystyrene resin (HIPS), and acrylonitrile-styrene copolymer (AS). Resin) and the like; polyolefin resins such as polyethylene resins and polypropylene resins; polyamide resins; polyimide resins; polyether imide resins; polyurethane resins; polyphenylene ether resins; polyphenylene sulfide resins; .
In addition, 1 type may contain other resin and 2 or more types may contain it by arbitrary combinations and a ratio.

Resin additives Examples of resin additives include stabilizers, antioxidants, release agents, lubricants, fillers, flame retardants, ultraviolet absorbers, dyes and pigments, antistatic agents, antifogging agents, antiblocking agents, Examples thereof include a fluidity improver, a plasticizer, a dispersant, and an antibacterial agent. In addition, 1 type may contain resin additive and 2 or more types may contain it by arbitrary combinations and a ratio.

  Since the polycarbonate resin composition produced by the method of the present invention is excellent in slidability, heat resistance, mechanical properties, and electrical characteristics, for example, electrical equipment field, electronic equipment field, housing related field, automobile field, other It can be widely used for molded products or parts in various industrial fields.

The polycarbonate resin composition of the present invention is extruded in a strand form from an extrusion die at the tip of the extruder. The resin extruded from the discharge port of the die is manufactured through a process in which the resin is cut into a uniform length and a uniform size by a pelletizer. Specifically, the step of cutting the resin is extruded in the form of a strand from the discharge port of the resin extrusion die attached to the extruder in a state where the raw material resin and the additive are heated and melt-kneaded, and The strand is cooled by a cooling device such as a water tank or a mesh belt, and then cut by a pelletizer to form resin pellets.
There is no restriction | limiting in particular in the shape of an extrusion die, A well-known thing is used. The diameter of the die of the discharge nozzle is usually about 2 to 5 mm, although it depends on the extrusion pressure and the desired pellet size. The temperature of the polycarbonate resin immediately after being extruded is usually about 300 ° C.
The strand in the underwater cooling method is taken up by a take-up roller and cooled by being transported through the water stored in the cooling tank. In order to reduce the deterioration of the resin, it is better that the time from when the strand is pushed out of the die until entering the water is shorter. Normally, it is better to enter the water within 1 second after being pushed out of the die.

The electric conductivity of water when cooling in water is preferably 30 μS / cm or less. If the electrical conductivity of the water used exceeds 30 μS / cm, the cleanliness of the resulting polycarbonate resin pellets deteriorates. The electrical conductivity of water is preferably 20 μS / cm or less, more preferably 10 μS / cm or less, further preferably 5 μS / cm or less, particularly preferably 3 μS / cm or less, and most preferably 1 μS / cm or less.
The water stored in the cooling tank deteriorates with time, and the electrical conductivity increases. However, the electrical conductivity is kept within a predetermined range (30 μS / cm or less) by constantly supplying cooling water and causing the water to overflow from the tank. Can be kept in. Further, the temperature of the water tank varies depending on the position, and the temperature is usually highest when the strand enters the water tank, and the temperature of the water tank decreases as it cools. If the temperature of the water tank is too low, the strand is supercooled, and if the temperature of the water tank is high, the temperature of the strand is too high. A preferable range of the temperature of the water tank is 30 ° C to 90 ° C, and a more preferable range is 40 ° C to 70 ° C.

  The cooled strand is sent to a pelletizer by a take-off roller, and is cut into pellets. Cutting is preferably performed when the strand temperature is in the range of 70 to 130 ° C, preferably 75 to 125 ° C.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

[Polycarbonate resin]
The following aromatic polycarbonate resins PC-1 to PC-2 were used as the polycarbonate resin.
・ PC-1
Product name “NOVAREX (registered trademark) 7022A” manufactured by Mitsubishi Engineering Plastics
Viscosity average molecular weight Mv: 21,000
MVR (300 ℃, 1.2kg load): 10.7 cm ^3/10 min water content: 0.24 wt%
Hereinafter, it is referred to as “PC-1”.
・ PC-2
Product name "Novalex (registered trademark) 7022A" manufactured by Mitsubishi Engineering Plastics
Viscosity average molecular weight Mv: 20,900
MVR (300 ℃, 1.2kg load): 10.9cm ^3/10 min moisture content 0.38 wt%
Hereinafter, it is referred to as “PC-2”.

[Fluoropolymer without fibril-forming ability]
The following polytetrafluoroethylene was used as a fluororesin having no fibril forming ability.
・ Product name "Lebron L-5" manufactured by Daikin Industries, Ltd.
Polytetrafluoroethylene fine particles, average particle size: 5 μm
Hereinafter, it is referred to as “PTFE-1”.
・ Product name "Lebron L-7" manufactured by Daikin Industries
Polytetrafluoroethylene fine particles, average particle size: 5 μm
Hereinafter, it is referred to as “PTFE-2”.

[Fluoropolymer with fibril-forming ability]
The following polytetrafluoroethylene was used as a fluororesin having fibril-forming ability.
・ Product name "Polyflon FA500", manufactured by Daikin Industries
Polytetrafluoroethylene fine particles, average particle size: 430 μm
Hereinafter, it is referred to as “PTFE-3”.

[Extruder]
As the twin screw extruder, a meshing type co-rotating twin screw screw vented extruder (TEX44αII manufactured by Nippon Steel Works, screw diameter 47 mm) was used.
As the vent configuration and screw of the extruder, three screw types (A), (B), and (C) shown in FIG. 2 were prepared.
In FIG. 2, the symbols and names are as follows.
Z1: Polycarbonate resin supply / conveyance / preheating zone Z2: Polycarbonate resin melting zone Z3: Fluorine resin supply / conveyance / kneading zone Z4: Volatilization / extrusion zone 2: Main hopper (polycarbonate resin supply port)
3: Side feed supply port 4: Vacuum vent port 3 + 4: Side feed supply port (also used as open vent)
5: Vacuum vent port 3X: Side feed supply port (vent port closed)

Example 1
"TEX44αII" meshing type co-rotating twin screw made by Nippon Steel Co., Ltd. with a total of 10 barrels (referred to as C1 to C10 cylinders from upstream) having supply ports at C1 at the most upstream and C11 downstream thereof An extruder was used. The extruder configuration and screw pattern used were those described in FIG.
That is, a main hopper 15 is provided in the most upstream part C1, a barrel serving as a side feed port and an open vent port is provided as C16 in the downstream C6, and a vacuum vent port 17 is provided in the downstream C9. From the upstream side to the downstream side of the extruder, it is composed of a polycarbonate resin supply / conveyance / preheating zone 11, a polycarbonate resin melting zone 12, a fluororesin supply / conveyance / kneading zone 13, and a devolatilization / extrusion zone 14. A kneading disk for kneading and a kneading disk are provided, and the fluororesin conveying part is composed of a full flight screw having a ratio L / D of a screw lead length L to a screw diameter D of 1.5. A screw was used.
In addition, the set temperature of each cylinder was 30 degreeC for C1-C2, 300 degreeC for C3-C5, 200 degreeC for C6-C7, and 250 degreeC for C8-C10. A resin thermometer was installed in the fluororesin supply zone C6.

85 parts by mass of the polycarbonate resin PC-1 described above was supplied from the C1 main hopper 15, and then 15 parts by mass of the fluororesin PTFE-2 was supplied from the C6 side feeder port 16 using a side feeder. The kneading was performed under the conditions of a screw rotation speed of 250 rpm and a discharge amount of 120 kg / hr. The first vent port 16 was an open vent, the second vent port 17 was a vacuum vent, and the respective pressures were normal pressure (760 mmHg) and 25 mmHg. The specific energy at this time was 0.10 kWh / kg, and the resin temperature in the fluororesin kneading zone 14 was 311 ° C.
No vent-up from the first vent port 16 was observed, and it was confirmed that the supply of fluororesin from the side feeder was stable for 3 hours or more.
The molten resin composition extruded in a strand form from the extrusion die at the tip of the extruder is rapidly cooled in a water tank containing pure water having an electric conductivity of 0.7 μS / cm, and pelletized using a pelletizer to form a polycarbonate resin composition Pellets were obtained.

(Examples 2-4, Comparative Examples 1-4)
In Example 1, pellets of a polycarbonate resin composition were obtained in the same manner except that the extruder configuration, screw type, raw material blending conditions, and extrusion conditions described in Tables 1 and 2 below were used.

[Evaluation method]
The evaluation method is as follows.
Specific energy measurement:
Measure the motor output P (kW) of the twin screw extruder, multiply by the motor power factor of 0.9, calculate the power consumption of the extruder motor, and divide the power consumption by the discharge amount Q (kg / h). And asked.

Bent up from the first vent of fluororesin:
The presence or absence of vent-up (spout) from the first vent port of the fluororesin was judged visually. When the fluororesin adheres around the vent port, vent-up occurs, and when only gas comes out of the vent, it is determined that no vent-up occurs.

Feed stability of fluororesin:
The side feed stability of the fluororesin was judged by visual observation from the side feeder as to whether it can be stably bitten or not. The status of stable supply was confirmed for 3 hours.

Dispersion particle diameter of fluororesin (D50):
The obtained pellet was cut with a diamond cutter in a direction perpendicular to the flow direction, and the cross-section thereof was scanned with a scanning electron microscope (SEM), and the diameter of 50 particles was arbitrarily selected in a selected field of view. It was measured. When the particle was not spherical, the maximum value of the distance from the end of the particle to the opposite end was taken as the particle diameter, and image processing by a computer was performed for measurement.
The measured values thus obtained are arranged according to the expression of the particle measurement results shown in JIS Z8819-1: 1999 (in agreement with ISO92776-1: 1998), and the integral fraction of the obtained integral distribution map The particle diameter corresponding to 50% was defined as the dispersed particle diameter D50 of the present invention.
The evaluation results are shown in Tables 1 and 2 below.

  Since the production method of the present invention can supply a fluororesin with a polycarbonate resin composition having a low dispersibility of the fluororesin without any trouble in operation in an extruder and can supply the fluororesin continuously and stably over a long period of time. The above usability is very high.

1: Twin screw extruder 2: Main hopper 3: Side feed supply port 4, 5: Vent port 6, 7: Feeder

Claims (4)

  Using a twin screw extruder having a main hopper, a side feeder and a vent port, 80 to 97 parts by mass of polycarbonate resin is supplied from the main hopper, and 20 to 3 parts by mass of fluororesin having no fibril forming ability is supplied from the side feeder. A method for producing a polycarbonate resin composition that is supplied and melt-kneaded, wherein at least one vent port is provided at a joint portion of a side feeder and a twin-screw extruder or upstream thereof, and a specific energy is 0.05 to 0.00. The manufacturing method of the polycarbonate resin composition characterized by being in the range of 15 kW * Hr / kg.   The method for producing a polycarbonate resin composition according to claim 1, wherein the vent port is an open vent or a vacuum vent.   The screw of the fluororesin conveying part is selected from a full flight screw, a square flight screw, and a single wide flight screw having a ratio L / D of a screw lead length L to a screw diameter D of 0.5 to 2.0. The manufacturing method of the polycarbonate resin composition of Claim 1 or 2 comprised by the screw element made.   The screw configuration between the vent port and the fluororesin supply port is a seal ring or reverse lead flight screw in which the ratio L / D of the screw lead length L to the screw diameter D is 0.3 to 2.0. The manufacturing method of the polycarbonate resin composition in any one of Claims 1-3 containing.