JP5619507B2 - Method for producing liquid crystalline resin composition, liquid crystalline resin composition, and apparatus for producing liquid crystalline resin - Google Patents

Description

  The present invention relates to a method for producing a liquid crystalline resin composition in which a liquid crystalline resin and a filler are melt-kneaded using a twin screw extruder.

  Liquid crystalline resins typified by liquid crystalline polyester resins are widely used as high-performance engineering plastics because they have excellent mechanical strength, heat resistance, chemical resistance, electrical properties, and the like in a balanced manner. In particular, most of the liquid crystalline resin is used for injection molding.

  Liquid crystalline resins are usually used as liquid crystalline resin compositions filled with fibrous fillers such as glass fibers and carbon fibers, and granular fillers such as silica, mica, clay and glass beads, and plate-like fillers. ing. Since the liquid crystalline resin composition filled with various fillers has a good balance between fluidity and mechanical strength, for example, relay parts, coil bobbins, connectors, volume parts, motor parts such as commutators and separators, Alternatively, it is suitably used as a material for electric / electronic parts having a thin portion or a complicated shape such as a sealing material for an element such as a coil, a crystal resonator, or an IC chip.

  As a method for producing such a liquid crystalline resin composition, for example, a main feed port is provided at the upstream portion in the extrusion direction, a side feed port is provided at the downstream portion in the extrusion direction, and a specific distance downstream from the side feed port in the cylinder. Liquid crystal resin is supplied from the main feed port and filler is supplied from the side feed port using a twin-screw kneading extruder provided with a kneading part in which screw pieces such as kneading disks are arranged at remote positions. A method of melt-kneading a functional resin and a filler is known (Patent Document 1).

JP 2006-035677 A

  However, in the method described in Patent Document 1, the resin easily adheres to the full flight screw between the side feed port and the kneading part, and the resin adhering to the screw piece is oxidized by the air brought into the extruder together with the filler. As a result, a black foreign substance called black spec (hereinafter also referred to as BS) is generated, and there is a problem that the black spec is mixed into the liquid crystalline resin composition.

  When the liquid crystalline resin composition contains black specifications, there is a problem that the appearance of the molded product is impaired. Furthermore, since the liquid crystalline resin composition is excellent in fluidity, it is often used as a molding material for complex-shaped electric / electronic parts having a thin part. When the size of the black spec is large, such a thin part is used. There is a problem that a short shot is generated due to blockage in a black spec mold when a part having the above is formed.

  The present invention has been made to solve the above problems, and a method for producing a liquid crystalline resin composition with reduced generation of black specs, a liquid crystalline resin composition having a low black spec content, and It aims at providing the apparatus for liquid crystalline resin composition manufacture with little content of a black specification.

  When the present inventors produce a liquid crystalline resin composition by melt-kneading a liquid crystalline resin and a filler, a liquid crystalline resin supply port is provided at an upstream end in the extrusion direction, and a downstream end in the extrusion direction. A discharge die, a filler supply port in the middle of the liquid crystal resin supply port and the discharge die, and a first vent port downstream of the filler supply port, and in the cylinder, upstream of the liquid crystal resin supply port A plasticizing section is provided on the side, a first kneading zone is provided by arranging a kneading element having transportability toward the downstream starting from the upstream end of the filler supply port, and the first kneading zone By using a twin-screw extruder provided with a kneading section in the section from the downstream end of the first vent to the upstream end of the first vent port, it is found that the occurrence of black specs is reduced, and the present invention is It came to be completed.

(1) A method for producing a liquid crystalline resin composition by melt-kneading a liquid crystalline resin and a filler using a twin screw extruder,
The biaxial extruder has a liquid crystal resin supply port at the upstream end in the extrusion direction, a discharge die at the downstream end in the extrusion direction, a filler supply port between the liquid crystal resin supply port and the discharge die, and The first vent port is provided downstream from the filler supply port,
The twin-screw extruder includes a plasticizing portion in the cylinder upstream of the filler supply port, and a first kneading zone from the upstream end of the filler supply port toward the downstream. A kneading part is provided in the section from the downstream end of the first kneading zone to the upstream end of the first vent port,
A method for producing a liquid crystalline resin composition, wherein the first kneading zone is composed of a kneading element having transportability.

  (2) The method for producing a liquid crystalline resin composition according to (1), wherein the length of the first kneading zone is 5 to 15 in a ratio L / D of the screw effective length L and the screw diameter D.

  (3) The liquid crystalline resin composition according to (1) or (2), wherein the biaxial extruder further includes a second vent port at the same position as the filler supply port or upstream of the filler supply port. Manufacturing method.

  (4) The twin-screw extruder includes the second vent port on the upstream side of the filler supply port, and further fills the cylinder from the lower portion of the upstream end of the second vent port. The liquid crystalline resin composition according to (3), wherein a second kneading zone is provided in a lower section of the upstream end of the material supply port, and the second kneading zone is constituted by a kneading element having transportability. Manufacturing method.

  (5) The length of the second kneading zone is 70 to the length of the section from the lower part of the upstream end of the second vent port to the lower part of the upstream end of the filler supply port. % Or more, The manufacturing method of the liquid crystalline resin composition of (4) description.

  (6) The liquid crystal according to any one of (1) to (5), wherein the kneading element having transportability is formed by stacking a kneading disk while shifting so that a phase angle is larger than 0 and smaller than 90 ° C. For producing a conductive resin composition.

(7) The method for producing a liquid crystalline resin composition according to any one of (1) to (6), wherein a bulk specific gravity of the filler is 0.6 g / cm ³ or less.

(8) The method for producing a liquid crystalline resin composition according to (7), wherein the bulk specific gravity of the filler is 0.35 g / cm ³ or less.

  (9) The method for producing a liquid crystalline resin composition according to any one of (1) to (8), wherein the filler comprises one or more selected from the group consisting of talc, mica, silica, and glass powder. .

  (10) A liquid crystalline resin composition produced by the method according to any one of (1) to (9).

(11) A biaxial extruder comprising a liquid crystalline resin supply port at the upstream end in the extrusion direction and a discharge die at the downstream end in the extrusion direction,
The biaxial extruder includes a filler supply port between the liquid crystalline resin supply port and the discharge die, and includes a first vent port downstream of the filler supply port,
The twin-screw extruder includes a plasticizing portion in the cylinder upstream of the filler supply port, and a first kneading zone from the upstream end of the filler supply port toward the downstream. A kneading part is provided in the section from the downstream end of the first kneading zone to the upstream end of the first vent port,
An apparatus for producing a liquid crystalline resin composition, wherein the first kneading zone is constituted by a kneading element having transportability.

  (12) The biaxial extruder further includes a second vent port at the same position as the filler supply port or upstream of the filler supply port, for producing a liquid crystalline resin composition according to (11) Equipment.

  (13) The twin-screw extruder further includes a second kneading in a section of a lower portion of the upstream end portion of the filler supply port from a lower portion of the upstream end portion of the second vent port in the cylinder. The apparatus for producing a liquid crystalline resin composition according to (12), comprising a zone, wherein the second kneading zone is constituted by a kneading element having transportability.

  According to the present invention, when a liquid crystalline resin and a filler are melt-kneaded to produce a liquid crystalline resin composition, a liquid crystalline resin supply port is provided at an upstream end in the extrusion direction, and a downstream end in the extrusion direction. A discharge die, a filler supply port in the middle of the liquid crystal resin supply port and the discharge die, and a first vent port downstream from the filler supply port, and the upstream side of the filler supply port in the cylinder Is provided with a plasticizing section, and a first kneading zone is provided in which a kneading element having transportability is disposed downstream from the upstream end of the filler supply port, and downstream of the first kneading zone. By using a twin-screw extruder provided with a kneading section in the section from the side end to the upstream end of the first vent port, the generation of black specs can be reduced.

It is a schematic diagram of the cross section of the twin-screw extruder used in this invention. It is a figure which shows an example of the kneading element used in this invention.

  Hereinafter, an embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiment, and may be implemented with appropriate modifications within the scope of the object of the present invention. it can.

  In the present invention, when a liquid crystalline resin and a filler are melt-kneaded to produce a liquid crystalline resin composition, the liquid crystalline resin supply port is discharged at the upstream end in the extrusion direction and the downstream discharge is discharged at the downstream end in the extrusion direction. Using a biaxial extruder with a die, a liquid crystal resin supply port and a discharge die between the filler supply port and a first vent port downstream from the filler supply port, in the cylinder of the biaxial extruder The plasticizing part is provided on the upstream side of the filler supply port, and the first kneading zone in which the kneading elements having the transportability are arranged downstream from the upstream end of the filler supply port is provided. The kneading part is provided in a section from the downstream end of the first kneading zone to the upstream end of the first vent port.

  Here, although the kneading element having transportability has only transportability, the transportability is inferior to an element specialized for a transport function such as a full flight element. For this reason, conventionally, when a thermoplastic resin and a filler are melt-kneaded using a twin-screw extruder, the filler is supplied from a vent port provided upstream of the filler supply port in order to vent air in the twin-screw extruder. In the section between the mouth and the section from the filler supply port to the downstream kneading section, the kneading element is used because the molten resin may flow backward to the filler supply port due to the pressure increase in the twin screw extruder. It was not used.

  However, according to the study by the present inventors, a section from the filler supply port to the downstream kneading section, or a section between the vent port upstream of the filler supply port in the twin-screw extruder and the filler supply port. Even when a kneading element is disposed on the liquid crystal resin composition, when a liquid crystal resin is used, the liquid crystal resin composition does not have a large influence on the discharge amount without causing a back flow of the molten resin from the vent port or the filler supply port. In addition, it has been discovered that the conventional technology can reduce the occurrence of black specs. Such an effect is presumed to have been realized by the fact that a significant pressure increase did not occur at the location where the kneading element was arranged in the twin screw extruder because the melt viscosity was low as a general property of the liquid crystalline resin.

[Liquid crystal resin]
The liquid crystalline resin used in the present invention refers to a melt processable polymer having a property capable of forming an optically anisotropic molten phase. The property of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarizing microscope and observing a molten sample placed on a Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times. When the liquid crystalline resin applicable to the present invention is inspected between crossed polarizers, the polarized light is normally transmitted even in a molten stationary state, and optically anisotropic.

  The liquid crystalline resin as described above is not particularly limited, but is preferably an aromatic polyester or an aromatic polyester amide, and a polyester partially including an aromatic polyester or an aromatic polyester amide in the same molecular chain is also within the range. It is in. They preferably have a logarithmic viscosity (IV) of at least about 2.0 dl / g, more preferably 2.0 to 10.0 dl / g when dissolved in pentafluorophenol at 60 ° C. at a concentration of 0.1% by weight. .) Are used.

  The aromatic polyester or aromatic polyester amide as the liquid crystalline resin applicable to the present invention is particularly preferably at least one compound selected from the group of aromatic hydroxycarboxylic acids, aromatic hydroxyamines, and aromatic diamines. Aromatic polyesters and aromatic polyester amides as constituent components. Further, two or more kinds of liquid crystalline resins may be blended and used.

More specifically,
(1) A polyester mainly composed of one or more aromatic hydroxycarboxylic acids and derivatives thereof;
(2) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids and derivatives thereof; c) Polyester comprising at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof;
(3) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more of aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). A polyester amide comprising one or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof;
(4) mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof; (b) one or more of aromatic hydroxyamines, aromatic diamines and derivatives thereof; and (c). One or more of aromatic dicarboxylic acid, alicyclic dicarboxylic acid and derivatives thereof, and (d) at least one or more of aromatic diol, alicyclic diol, aliphatic diol and derivatives thereof, and And polyester amides composed of Furthermore, you may use a molecular weight modifier together with said structural component as needed.

（Ｘ：アルキレン（Ｃ１からＣ４）、アルキリデン、−Ｏ−、−ＳＯ−、−ＳＯ_２−、−Ｓ−、−ＣＯ−より選ばれる基である）

（Ｙ：−（ＣＨ_２）_ｎ−（ｎ＝１から４）、−Ｏ（ＣＨ_２）_ｎＯ−（ｎ＝１から４）より選ばれる基である。） Preferable examples of specific compounds constituting the liquid crystalline resin applicable to the present invention include p-hydroxybenzoic acid, aromatic hydroxycarboxylic acids such as 6-hydroxy-2-naphthoic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, resorcin, aromatic diols such as compounds represented by the following general formula (I) and the following general formula (II); terephthalic acid, isophthalic acid, 4 , 4′-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid and aromatic dicarboxylic acids such as compounds represented by the following general formula (III); aromatic amines such as p-aminophenol and p-phenylenediamine Can be mentioned.

(X: C4 alkylene (C1), _{alkylidene, -O -, - SO -,} - SO 2 -, - S -, - is a group selected from CO-)

(Y is a group selected from — (CH ₂ ) _n — (n = 1 to 4) and —O (CH ₂ ) _n O— (n = 1 to 4).

  The objective of this invention is reducing generation | occurrence | production of the black specification at the time of manufacturing a liquid crystalline resin composition using a twin-screw extruder. When a high melting point liquid crystalline resin and a filler are melt-kneaded using a twin screw extruder, the temperature difference between the temperature of the filler supplied into the twin screw extruder and the molten liquid crystalline resin is large. When the low temperature filler comes into contact with the molten liquid crystal resin, the temperature of the molten liquid crystalline resin is lowered, and the viscosity of the liquid crystalline resin temporarily increases. For this reason, the liquid crystalline resin easily adheres to the screw, and the resin adhering to the screw stays in the twin screw extruder, so that BS is particularly likely to occur.

  For the above-described reason, the method for producing a liquid crystalline resin composition according to the present invention uses, for example, a liquid crystalline resin composition that uses a high melting point liquid crystalline resin that easily generates BS having a melting point of 330 ° C. or higher, more preferably 350 ° C. or higher. When manufacturing a product, a remarkable effect of reducing the occurrence of BS can be obtained.

[Filler]
In the present invention, the filler to be blended with the liquid crystal polyester is not particularly limited, and various fillers such as a fibrous filler, a granular filler, and a plate filler can be used. Examples of fibrous fillers include glass fiber, asbestos fiber, silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, Examples thereof include inorganic fibrous materials such as metallic fibrous materials such as titanium, copper, and brass. As the granular filler, silicic acid such as carbon black, graphite, silica, quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, wollastonite Salts, iron oxide, titanium oxide, zinc oxide, antimony trioxide, oxides of metals such as alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, other ferrites, Examples thereof include silicon carbide, silicon nitride, boron nitride, and various metal powders. Examples of the plate-like filler include mica, glass flakes, various metal foils and the like. These fillers may be used in combination of two or more.

Among these fillers, the content of air is large. For example, the bulk specific gravity is 0.6 g / cm ³ or less, more preferably the bulk specific gravity is 0.35 g / cm ³ or less, and further preferably 0.25 g / cm ^3. When the following filler is used, BS is likely to be generated due to oxidation of the liquid crystalline resin in the twin-screw extruder. The method for producing a liquid crystalline resin composition of the present invention can satisfactorily reduce the occurrence of BS when producing a liquid crystalline resin composition, even when using a filler with a high air content. It is particularly suitably used for the production of a liquid crystalline resin composition containing a filler having a bulk specific gravity of 0.6 g / cm ³ or less, more preferably 0.35 g / cm ³ or less, and even more preferably 0.25 g / cm ³ or less. .

  Examples of the filler that is preferably used in the present invention and has a high air content and a small bulk specific gravity include those containing at least one selected from the group consisting of talc, mica, silica, and glass powder. It is done.

  The bulk specific gravity of the filler can be measured by the JIS K5101 method.

  The blending amount of the filler with respect to the liquid crystalline resin is not particularly limited as long as the object of the present invention is not impaired, and is usually 200 parts by mass or less, more preferably 150 parts by mass or less, with respect to 100 parts by mass of the liquid crystalline resin. Most preferably, it mix | blends in the ratio of 100 mass parts or less.

[Other ingredients]
In the present invention, when the liquid crystalline resin composition is produced, in addition to the filler, the thermoplastic resin other than the liquid crystalline resin and the nucleating agent are within the range that does not impair the purpose of the present invention with respect to the liquid crystalline resin. Additives such as colorants, antioxidants, stabilizers, plasticizers, lubricants, mold release agents, flame retardants, and the like may be blended.

[Twin screw extruder]
Hereinafter, the structure of the twin-screw extruder used for this invention is demonstrated based on attached FIG. FIG. 1 is a diagram schematically showing a cross section of a twin-screw extruder used in the present invention.

  The twin-screw extruder 1 used in the present invention has a liquid crystal resin supply port 11 at the upstream end in the extrusion direction, a discharge die 14 at the downstream end in the extrusion direction, and an intermediate between the liquid crystal resin supply port 11 and the discharge die 14. And a first vent port 13 on the downstream side of the filler supply port 12. Further, the twin-screw extruder 1 used in the present invention includes a plasticizing portion 15 on the upstream side of the filler supply port 12 in the cylinder, and starts downstream from the upstream end of the filler supply port 12. The first kneading zone 17 is provided, and the kneading portion 16 is provided in a section from the downstream end portion of the first kneading zone 17 to the upstream end portion of the first vent port 13.

  In the specification and claims of the present application, when “upstream” or “downstream” is simply described, “upstream in the extrusion direction of the twin screw extruder” or “extrusion direction of the twin screw extruder”, respectively. "Downstream of".

  The twin-screw extruder 1 used in the present invention is not particularly limited as long as the object of the present invention is not hindered. Preferably, a complete meshing and co-rotating twin-screw extruder is used. In the twin-screw extruder 1 used in the present invention, the ratio L / D between the effective screw length (L) and the screw diameter (D) is preferably 20 to 70, and more preferably 30 to 60. If L / D is smaller than 20, the effective screw length is too short with respect to the screw diameter, so that it is difficult to provide the first kneading zone 17, and if L / D is larger than 70, the liquid crystalline resin Thermal degradation is likely to occur.

[Plasticizing section and kneading section]
The twin-screw extruder 1 used in the present invention includes a plasticizing part 15 and a kneading part 16 in a cylinder. The plasticizing portion 15 is a section in the cylinder of the twin screw extruder 1 where the liquid crystalline resin is sufficiently melted by applying shearing force to the liquid crystalline resin to generate heat. The kneading part 16 is a section for sufficiently kneading the liquid crystalline resin and the filler in a molten state and uniformly dispersing the filler in the liquid crystalline resin.

  The length of the plasticizing portion 15 is preferably 2.0 to 7.5 in terms of L / D, more preferably 4.5 to 6.5, and the length of the kneading portion 16 is L / D. It is preferably from 3.5 to 10.0, more preferably from 3.5 to 7.0.

  The screw elements constituting the plasticizing portion 15 and the kneading portion 16 are not particularly limited as long as the liquid crystalline resin can be sufficiently plasticized in the plasticizing portion 15 or the filler can be sufficiently dispersed in the kneading portion 16. Various screw elements can be used. General screw elements used in the plasticizing section 15 and the kneading section 16 include a forward kneading element (kneading element having a transportability described later) and a reverse kneading element (the contents of the twin-screw extruder 1 are upstream. Selected from a kneading element that pushes back in the direction), a neutral kneading element (an element that does not have a transport force formed by shifting kneading discs at a phase angle of 90 °, and overlapping), a mixing element, and the like. Things.

[First Kneading Zone]
The twin-screw extruder 1 used in the present invention is provided with a first kneading zone 17 in the cylinder, starting from the lower part of the upstream end portion of the filler supply port 12 toward the downstream. The first kneading zone 17 of the twin-screw extruder 1 used in the present invention is constituted by a kneading element having transportability. Here, the kneading element having transportability has a capability of transporting the liquid crystalline resin composition in a molten state downstream in the extrusion direction, and a clearance portion between the inner wall of the cylinder and the tip portion of the kneading element. The liquid crystalline resin composition is not particularly limited as long as it can apply a shearing force to disperse the filler in the liquid crystalline resin. The clearance between the inner wall of the cylinder and the tip portion of the kneading element having transportability is preferably 3 mm or less, and more preferably 1 mm or less. If the clearance is too wide, a sufficient kneading effect may not be obtained and the filler may not be dispersed well.

(Kneading element with transportability)
Specific examples of kneading elements having transportability include kneading elements constructed by stacking kneading discs so that the phase angle (θ) is larger than 0 and smaller than 90 °, and the tip portion is the outer periphery of the element. And a rotor-type kneading element formed while being continuously twisted. As a kneading element with transportability, it is excellent in the effect of uniformly dispersing the filler in the liquid crystalline resin, and the phase angle of the kneading disk is easy in that the air in the extruder easily escapes through the space between the kneading disks. It is more preferable to use a kneading element that is formed by being overlapped while being shifted so as to be larger than 0 and smaller than 90 °.

  The first kneading zone 17 does not impair the object of the present invention, and is configured by combining a kneading disk having transportability and other screw elements as long as the first kneading zone 17 does not lose transportability as a whole. Also good. Other screw elements include mixing elements such as a back mixing screw.

  FIG. 2 is a schematic view of an example of a kneading element preferably used in the present invention as seen from a direction parallel to the rotation axis and a direction perpendicular to the rotation axis. The kneading element 2 is configured by overlapping the kneading disks 21 while shifting so that the phase angle (θ) is larger than 0 and smaller than 90 °.

  Hereinafter, a kneading element in which the kneading disks are overlapped while shifting so that the phase angle is larger than 0 ° and smaller than 90 ° will be described.

  When the kneading element having transportability is configured by overlapping the kneading disks, the phase angle between the respective kneading disks may be the same or different. The phase angle is more preferably 5 to 80 °, even more preferably 10 to 70 °, and most preferably 15 °, 30 °, 45 ° or 60 °. A kneading element constituted by overlapping the kneading discs while shifting the kneading disk within such a phase angle has good transportability.

  Although the thickness of each kneading disk constituting the kneading element used in the present invention may be the same or different, the kneading element is usually constituted by using a kneading disk having the same thickness. The thickness of the kneading disk is not particularly limited as long as the object of the present invention is not impaired, and can be appropriately selected from those usually used for melt kneading of resins.

  In the present invention, since the first kneading zone 17 is provided from the lower end of the upstream end of the filler supply port 12 in the cylinder of the twin screw extruder 1 toward the downstream, the liquid crystal is formed at the tip portion of the kneading element. Due to the generation of heat by applying shearing force to the functional resin composition, the decrease in the resin temperature due to the mixing of the low temperature filler and the high temperature molten resin is suppressed, and the self-cleaning property of the kneading element itself , Adhesion of the liquid crystalline resin composition causing BS generation to the inside of the twin-screw extruder 1 is suppressed.

  Moreover, the air brought into the twin-screw extruder 1 together with the filler can be degassed from the molten liquid crystalline resin composition by the excellent kneading action of the kneading element. For this reason, it becomes possible to discharge | emit at least one part of the air brought in with the inside of the biaxial extruder 1 with the filler from the filler supply port 12 to the exterior of the biaxial extruder 1. FIG. Thereby, generation | occurrence | production of BS by the oxidation of liquid crystalline resin inside the biaxial extruder 1 is suppressed.

  Further, in the first kneading zone 17, since a kneading element having transportability is used, when the filler is supplied to the inside of the twin-screw extruder 1, 2 is provided below the filler supply port 12. The internal pressure of the shaft extruder 1 does not increase rapidly, and the liquid crystalline resin composition is unlikely to flow backward from the filler supply port 12.

  The length of the first kneading zone 17 is L / D, preferably 2 to 15, more preferably 5 to 15, and even more preferably 5 to 10. By providing the first kneading zone 17 with such a length, a shearing force is applied to the liquid crystalline resin composition at the tip portion of the kneading element to generate heat, thereby mixing the low temperature filler and the high temperature molten resin. The lowering of the resin temperature due to the kneading element and the self-cleaning property of the kneading element itself suppress the adhesion of the liquid crystalline resin composition causing the occurrence of BS to the inside of the biaxial extruder 1, Generation can be reduced.

  The starting point of the first kneading zone 17 is not particularly limited as long as it is the upstream end of the filler supply port 12. Further, the first kneading zone 17 is 2 or less, preferably 1 or less away in L / D from the lower part of the upstream end of the filler supply port 12 toward the downstream as long as the object of the present invention is not impaired. It may be a position.

  Moreover, the 1st kneading zone 17 and the kneading part 16 may be provided continuously. In such a case, the total length of the first kneading zone 17 and the kneading part 16 is preferably 5.5 to 25.0, and more preferably 8.5 to 22.0 in terms of L / D.

[First vent port]
In the twin-screw extruder 1 used in the present invention, a first vent port 13 is installed on the downstream side of the kneading section 16. The 1st vent port 13 is installed for deaeration of the gas etc. which arise at the time of kneading | mixing resin and a filler. Further, the first vent port 13 is normally depressurized and deaerated by a vacuum pump. When the first vent port 13 is decompressed, the degree of decompression is preferably 0 to 380 Torr (0 to 50.7 kPa), more preferably 1 to 200 Torr (0.13 to 26.7 kPa), and more preferably 10 to 100 Torr (1. 3 to 13.3 kPa) is particularly preferred.

[Second vent port]
The twin-screw extruder 1 used in the present invention preferably further includes a second vent port 18. The second vent port 18 is provided at the same position as the filler supply port 12 of the twin-screw extruder 1 or on the upstream side of the filler supply port 12. Here, the filler supply port 12 and the second vent port 18 are provided at “the same position” means that the filler supply port 12 and the second vent port 18 are extruded on the twin-screw extruder 1. It means that they are arranged in parallel in the vertical direction. In the case where the second vent port 18 is provided in the twin-screw extruder 1, the plasticizing portion 15 is disposed on the upstream side of the second vent port 18. In addition, since the 2nd vent port discharges the air inside the twin-screw extruder 1, it is normally used as an open vent.

By providing the second vent port 18 in the twin screw extruder 1, the air brought into the twin screw extruder 1 together with the filler from the filler supply port 12 is discharged from the twin screw extruder 1. Therefore, the effect of reducing the occurrence of BS by the first kneading zone 17 can be improved. Further, when a filler containing a large amount of air having a bulk specific gravity of 0.6 g / cm ³ or less is used, the improvement in the effect of reducing BS generation by providing the second vent port 18 becomes more remarkable.

  When the second vent port 18 is provided on the upstream side of the filler supply port 12, the length of the section from the lower portion of the upstream end portion of the second vent port 18 to the lower portion of the upstream end portion of the filler supply port 12. The L / D is preferably 2.5 to 10.5, and more preferably 2.5 to 7.0. When the length of the section of the lower part of the upstream end of the filler supply port 12 from the lower part of the upstream end of the second vent port 18 is too long (the second vent port 18 and the filler supply port 12 are separated from each other). The air taken into the twin-screw extruder 1 together with the filler is difficult to be smoothly discharged from the second vent port 18, and the first kneading zone 17 can reduce the occurrence of BS. It is difficult to improve.

[Second Kneading Zone]
When the second vent port 18 is provided on the upstream side of the filler supply port 12 in the twin-screw extruder 1, the upstream end portion of the second vent port 18 in the cylinder of the twin-screw extruder 1 is further provided. It is preferable to provide the second kneading zone 19 in the lower section of the upstream end portion of the filler supply port 12 from the lower portion.

  When the second kneading zone 19 is further provided in the twin-screw extruder 1, the second kneading zone 19 is constituted by a kneading element having the same transportability as the first kneading zone 17. In addition, the second kneading zone 19 is configured by combining a kneading disk having transportability and other screw elements as long as the second kneading zone 19 does not lose transportability without impairing the object of the present invention. May be. Other screw elements include mixing elements such as a back mixing screw.

In the present invention, by providing the second kneading zone 19, the air contained in the filler removed from the liquid crystalline resin composition in the molten state in the first kneading zone 17 is promptly passed through the second kneading zone 19. It becomes possible to discharge from the second vent port 18. Therefore, when the first kneading zone 17, the second vent port 18, and the second kneading zone 19 are provided in the twin screw extruder 1, the first kneading zone 17 and the second vent port are Compared with the case where the twin-screw extruder 1 is provided, a higher BS generation reduction effect can be obtained. Further, when a filler containing a large amount of air having a bulk specific gravity of 0.6 g / cm ³ or less is used, the improvement in the BS generation reduction effect by providing the second kneading zone 19 becomes more remarkable.

  The second kneading zone 19 has a length of 70% or more with respect to the length of the section from the lower end of the upstream end of the second vent port 18 to the lower end of the upstream end of the filler supply port 12. It is preferable that the length is 90% or more. By setting the second kneading zone 19 to such a length, the air brought into the twin screw extruder 1 together with the filler can be discharged particularly well to the outside of the twin screw extruder 1.

  The second kneading zone 19 may be provided continuously with the plasticizing part 15 as long as the object of the present invention is not impaired.

  In the twin-screw extruder 1 used in the present invention, the screw configuration in the section other than the first kneading zone 17, the second kneading zone 19, the plasticizing section 15, and the kneading section 16 in the cylinder is the kind of filler. In addition, a full flight element, a neutral kneading element, a forward kneading element, a reverse kneading element, a mixing element, and the like can be appropriately combined depending on the blending amount, the physical properties of the target liquid crystalline resin composition, and the like.

[Method for Producing Liquid Crystalline Resin Composition]
The method for producing the liquid crystalline resin composition of the present invention is in accordance with a conventionally known method except that the above-described twin screw extruder including the first kneading zone and the second kneading zone is used. What is necessary is just to melt-knead a material.

  When the liquid crystalline resin composition is produced by the method of the present invention, an inert gas can be introduced into the twin-screw extruder 1 from the second vent port 18 and / or the filler supply port 12. . When the inert gas is introduced into the twin-screw extruder 1, the air in the twin-screw extruder is replaced with the inert gas, so that the oxidation of the molten resin can be suppressed and the generation of BS is further reduced. It becomes possible. The inert gas introduced into the twin-screw extruder is not particularly limited as long as the object of the present invention is not impaired. For example, nitrogen, helium, argon, or the like can be used.

  By producing the liquid crystalline resin composition by the method of the present invention described above, the occurrence of BS in the twin-screw extruder is greatly reduced. Since the liquid crystalline resin composition produced by the method of the present invention has a very low BS content, it gives a molded product having an excellent appearance and is short-circuited due to BS when molding a molded product having a thin portion. Shots are unlikely to occur. Therefore, the liquid crystalline resin composition produced by the method of the present invention is a board-to-board (BtoB) connector or an FPC connector used to connect a flexible printed circuit board (FPC) and a flexible flat cable (FFC). It is particularly preferably used as a material for a molded product having a thin-walled portion.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

  In Examples and Comparative Examples, liquid crystalline resin compositions were produced using the following liquid crystalline resins and fillers.

<Liquid crystal resin>
The liquid crystalline resin obtained by the liquid crystalline resin production example described below was used.

[Production example of liquid crystalline resin]
The following monomers (I) to (IV), (V) metal catalyst, and (VI) acylating agent are added to a polymerization vessel equipped with a stirrer, reflux column, monomer inlet, nitrogen inlet, and pressure reduction / outflow line. I put it in.
(I) 166 g (48 mol%) of 2-hydroxy-6-naphthoic acid (HNA)
(II) 76 g (25 mol%) of terephthalic acid (TA)
(III) 4,4′-dihydroxybiphenyl (BP) 86 g (25 mol%)
(IV) 4-hydroxybenzoic acid (HBA) 5 g (2 mol%)
(V) Potassium acetate (catalytic amount)
(VI) Acetic anhydride (1.1 moles relative to the hydroxyl groups of HNA, BP, and HBA)

  Subsequently, after stirring at 140 ° C. for 1 hour under a nitrogen stream, the temperature was raised to 360 ° C. over 5.5 hours while continuing stirring. Next, the pressure was reduced to 5 Torr (667 Pa) over 30 minutes, and melt polymerization was performed while allowing low-boiling components such as acetic acid to flow out. After the stirring torque reached a predetermined value, nitrogen was introduced into the polymerization vessel to bring the inside of the polymerization vessel into a pressurized state, the polymer was discharged from the lower part of the polymerization vessel, and the strand was pelletized. The obtained pellet was heat-treated at 300 ° C. for 8 hours under a nitrogen stream, and used as a liquid crystalline resin. The melting point of the obtained liquid crystalline resin measured by a differential scanning calorimeter (DSC) was 352 ° C. The melting point was measured according to the following method.

[Measuring method of melting point]
Using a differential scanning calorimeter (Perkin Elmer DSC7), the polymer sample amount of about 10 mg was raised from 50 ° C. to 450 ° C. at a rate of 20 ° C./min, and then lowered to 50 ° C. at 20 ° C./min. The temperature was increased again to 450 ° C. at 20 ° C./min, and an endothermic thermogram was measured. The melting point (° C.) was determined from the value of the second endothermic peak.

<Filler>
Using mica and glass fiber as the filler, the liquid crystalline resin and the filler were melt-kneaded so that the mass ratio of liquid crystalline resin / mica / glass fiber was 68/22/10. The following mica and glass fiber were used.
Mica: AB-25S (manufactured by Yamaguchi Mica Industry Co., Ltd., average particle size 25 μm, bulk specific gravity 0.17 g / cm ³ )
Glass fiber: PF70E001 (milled glass fiber, manufactured by Nitto Boseki Co., Ltd., fiber diameter 10 μm, weight average length 70 μm, bulk specific gravity 0.5 g / cm ³ )

(Examples 1 to 3, Comparative Example 1, and Comparative Example 2)
The melt-kneading of the liquid crystalline resin and the filler is performed using TEX44αII (manufactured by Nippon Steel, Ltd., screw diameter 46.25 mm, L / D = 45.5, upstream end of the first vent port 13 as a twin screw extruder 1. The length L / D = 3.5 (161.9 mm) of the upstream end portion of the filler supply port 12 from the portion was performed under the conditions described in Table 1.

  The kneading elements 2 arranged in the first kneading zone 17 and the second kneading zone 19 have a transportability in which kneading disks 21 having a thickness of 4.7 to 14.1 mm are combined at a phase angle of 45 ° and 30 °. The kneading elements having the above were combined.

In each of the examples and comparative examples, the first kneading zone 17, the second kneading zone 19, the plasticizing unit 15, and the kneading unit 16 have the positions and lengths described in Table 2 and are the twin screw extruder 1 Placed in a cylinder. Further, the screw elements shown in Table 2 were arranged in the plasticizing part 15 and the kneading part 16. In Example 2 and Comparative Example 2, nitrogen was introduced into the twin screw extruder at a flow rate of 0.75 m ³ / hr from the filler supply port and the second vent port.

  The black spec content of the liquid crystalline resin compositions obtained in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 was measured by the following method. Table 4 shows the measurement results of the black spec content.

[Black spec evaluation method]
A liquid crystalline resin composition was formed into a film (2.5 g / sheet, film thickness 150 μm) under the conditions described in Table 3 using a film extruder (Laboplast Mill, manufactured by Toyo Seiki Seisakusho Co., Ltd.). Apply a white backlight to the film and visually check the size (0.2-0.3mm, 0.3-0.4mm, 0.4-0.5mm, ≧ 0.5mm) using a magnifying glass. The number of specs was confirmed. This black spec content confirmation operation was performed on 40 films (100 g) to determine the black spec content per unit weight.

  From Table 4, from the results of Comparative Example 1 and Comparative Example 2, it is not possible to sufficiently prevent oxidation of the liquid crystalline resin only by introducing nitrogen, which is an inert gas, into the twin screw extruder 1. It was confirmed that the effect of reducing BS generation was low.

  On the other hand, from the comparison between Example 1 and Example 2 and Comparative Example 1, by generating the first kneading zone 17 using a kneading element having a conveying force in the cylinder of the twin-screw extruder 1, the generation of BS It was confirmed that was significantly reduced. The liquid crystalline resin composition obtained in Example 1 has a significantly reduced occurrence of large BS of 0.3 mm or more, and is suitably used as a material for a molded product having a thin part of 0.3 mm or less. it can.

  From the results of Example 1 and Example 2, it was confirmed that introducing nitrogen into the twin-screw extruder 1 can further improve the effect of reducing BS generation. Further, from the results of Example 1 and Example 3, by providing the second kneading zone 19 in addition to the first kneading zone 17 in the twin screw extruder 1, the effect of reducing the occurrence of BS can be further improved. confirmed.

DESCRIPTION OF SYMBOLS 1 Twin screw extruder 11 Liquid crystalline resin supply port 12 Filler supply port 13 1st vent port 14 Discharge die 15 Plasticization part 16 Kneading part 17 1st kneading zone 18 2nd vent port 19 2nd kneading Zone 2 Kneading Element 21 Kneading Disc

Claims (13)

A method for producing a liquid crystalline resin composition by melt-kneading a liquid crystalline resin and a filler using a twin screw extruder,
The biaxial extruder has a liquid crystal resin supply port at the upstream end in the extrusion direction, a discharge die at the downstream end in the extrusion direction, a filler supply port between the liquid crystal resin supply port and the discharge die, and The first vent port is provided downstream from the filler supply port,
The twin-screw extruder includes a plasticizing portion in the cylinder upstream of the filler supply port, and a first kneading zone from the upstream end of the filler supply port toward the downstream. A kneading part is provided in the section from the downstream end of the first kneading zone to the upstream end of the first vent port,
The first kneading zone is constituted by a kneading element having transportability ;
The method for producing a liquid crystalline resin composition , wherein an upstream end of the first kneading zone is located at an upstream end of the filler supply port .   2. The method for producing a liquid crystalline resin composition according to claim 1, wherein the length of the first kneading zone is 5 to 15 in a ratio L / D of the screw effective length L and the screw diameter D. 3.   The method for producing a liquid crystalline resin composition according to claim 1 or 2, wherein the biaxial extruder further comprises a second vent port at the same position as the filler supply port or upstream of the filler supply port.   The twin-screw extruder includes the second vent port on the upstream side of the filler supply port, and further, the filler supply port from the lower portion of the upstream end of the second vent port in the cylinder. 4. The liquid crystalline resin composition according to claim 3, further comprising a second kneading zone in a lower section of the upstream end of the first kneading element, wherein the second kneading zone is constituted by a kneading element having transportability. Method.   The length of the second kneading zone is 70% or more with respect to the length of the section from the lower end of the upstream end of the second vent port to the lower end of the upstream end of the filler supply port. A method for producing a liquid crystalline resin composition according to claim 4. The liquid crystalline resin composition according to any one of claims 1 to 5, wherein the kneading element having transportability is obtained by stacking kneading disks while shifting so that the phase angle is larger than 0 and smaller than 90 ° . Production method. The manufacturing method of the liquid crystalline resin composition in any one of Claim 1 to 6 whose bulk specific gravity of the said filler is 0.6 g / cm < ³ > or less. The manufacturing method of the liquid crystalline resin composition of Claim 7 whose bulk specific gravity of the said filler is 0.35 g / cm < ³ > or less.   The method for producing a liquid crystalline resin composition according to any one of claims 1 to 8, wherein the filler comprises one or more selected from the group consisting of talc, mica, silica, and glass powder.   A liquid crystalline resin composition produced by the method according to claim 1. A biaxial extruder equipped with a liquid crystalline resin supply port at the upstream end in the extrusion direction and equipped with a discharge die at the downstream end in the extrusion direction;
The biaxial extruder includes a filler supply port between the liquid crystalline resin supply port and the discharge die, and includes a first vent port downstream of the filler supply port,
The twin-screw extruder includes a plasticizing portion in the cylinder upstream of the filler supply port, and a first kneading zone from the upstream end of the filler supply port toward the downstream. A kneading part is provided in the section from the downstream end of the first kneading zone to the upstream end of the first vent port,
The first kneading zone is constituted by a kneading element having transportability ;
An apparatus for producing a liquid crystalline resin composition , wherein an upstream end portion of the first kneading zone is located at an upstream end portion of the filler supply port .   The apparatus for producing a liquid crystalline resin composition according to claim 11, wherein the biaxial extruder further includes a second vent port at the same position as the filler supply port or upstream of the filler supply port. The twin-screw extruder further includes a second kneading zone in a section in a lower section of the upstream end portion of the filler supply port from a lower portion of the upstream end portion of the second vent port in the cylinder. The apparatus for producing a liquid crystalline resin composition according to claim 12, wherein the second kneading zone is constituted by a kneading element having transportability.

Images