JP2011207055A - Method of manufacturing liquid crystal polyester resin pellet and extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably manufacture a liquid crystal polyester resin pellet in a high yield by suppressing the occurrence of a strand breakage in a method of manufacturing the liquid crystal polyester resin pellet.SOLUTION: In the extruder, a screw 6 is provided in a barrel 3, and a die 5 is attached to a distal end of the barrel 3, and a nozzle 5b is formed on a distal end of the die 5. A cross section of an inside flow path 5d of the die 5 orthogonal to an axial direction of the screw 6 (direction of allows E and F) is reduced from a distal end 6a of the screw 6 to the nozzle 5b. When a maximum inside diameter of the barrel 3 is D, a distance from the distal end 6a of the screw 6 to an outlet 5c of the nozzle 5b is L, and a narrowing angle of the inside flow path 5d of the die 5 is θ, the extruder satisfies both of the following relational expressions (1) and (2). (1) L≤D and (2) 0°<θ≤45°.

Description

  The present invention relates to a pellet made of a liquid crystal polyester resin, that is, a method for producing a liquid crystal polyester resin pellet, and an extruder for producing the liquid crystal polyester resin pellet.

  Liquid crystalline polyester resins that exhibit liquid crystal properties when melted are excellent in heat resistance and fluidity when melted, that is, excellent in workability. It is used in various fields.

  In particular, a liquid crystal polyester resin composition (LCP compound) in which liquid crystalline polyester is filled with a fibrous reinforcing material represented by glass fiber or carbon fiber, or inorganic particles such as silica, mica, clay, glass beads, etc. is thin-walled. It is a material suitable for a part or a complex-shaped electric / electronic component. For example, it is used for sealing parts such as relay parts, coil bobbins, connectors, volume parts, motor parts such as commutators and separators, or elements such as coils, crystal oscillators and IC chips.

  However, the melt viscosity of the liquid crystal polyester resin has a large shear rate dependency and a large temperature dependency. Therefore, if there is a dead space, the liquid crystalline polyester resin tends to stay there, and the resin thus staying thickens, so that the strand breaks (hereinafter referred to as “strand break”) in the take-off process for cutting. May occur, and a pellet having a good shape may not be stably obtained. When the strand cannot be stably taken out, there arises a serious problem that the yield decreases in the pellet manufacturing process.

  In order to cope with such a problem, Patent Document 1 describes that a fiber-reinforced thermoplastic resin pellet is manufactured using a die having a through hole formed in a conical shape from a tip of a screw toward an outlet of a nozzle. Has been. Patent Document 2 describes that resin composition pellets are manufactured using a die holder whose flow path shape expands in a fan shape from the tip of the screw to the outlet of the nozzle.

JP-A-8-1662 (paragraphs [0016] and [0018], FIG. 1) JP 2000-117731 A (paragraph [0002] column, FIG. 2)

  However, the manufacturing method proposed in Patent Document 1 does not describe any knowledge about the distance from the tip of the screw to the outlet of the nozzle, and if this distance is long, the liquid crystal appears in a large dead space generated in front of the screw. Since the polyester stays and deteriorates, there is a problem that strand breakage occurs at the outlet of the nozzle.

  On the other hand, in the manufacturing method proposed in Patent Document 2, since the resin spreads in a fan shape in the die holder, there is a problem that the flow of the resin on the outermost periphery is slow and strand breaks frequently occur at the nozzle outlet.

  Accordingly, in view of such circumstances, the present invention is a liquid crystal polyester resin capable of stably producing liquid crystal polyester resin pellets with high yield by suppressing the occurrence of strand breakage and increasing the stability of the strand. A first object is to provide a method for producing pellets, and a second object is to provide an extruder suitable for carrying out such a method for producing liquid crystal polyester resin pellets.

  In order to achieve such an object, the present inventor considered that the shape of the die is to suppress the occurrence of strand breakage based on the characteristic of the liquid crystal polyester resin that the melt viscosity rapidly increases and decreases depending on the shear rate and temperature. The present invention has been completed by paying attention to defining the dimensions.

That is, according to the first aspect of the present invention, a screw is provided in the barrel, a die is attached to the tip of the barrel, a nozzle is formed at the tip of the die, and the shaft of the screw in the internal flow path of the die. By using an extruder whose cross-sectional area perpendicular to the direction decreases from the tip of the screw toward the nozzle, the liquid crystal polyester resin is melted and kneaded in the barrel and extruded from the nozzle to the outside of the die. When producing the polyester resin pellets, when the maximum inner diameter of the barrel is D, the distance from the tip of the screw to the outlet of the nozzle is L, and the narrowing angle of the internal flow path of the die is θ, the extruder Is a method for producing liquid crystal polyester resin pellets that satisfies both of the following relational expressions (1) and (2):
(1) L ≦ D
(2) 0 ° <θ ≦ 45 °

In addition to the configuration of claim 1, the invention described in claim 2 has a plurality of the nozzles, and when the pitch of these nozzles is A and the diameter of each nozzle is DA, the die is The relational expression (3) is satisfied.
(3) 2 ≦ A / DA ≦ 10

The invention described in claim 3 is characterized in that, in addition to the structure described in claim 1 or 2, the nozzle of the liquid crystal polyester resin has a shear rate of 500 to 5000 s ⁻¹ in the nozzle. .

  The invention described in claim 4 is characterized in that, in addition to the structure described in any one of claims 1 to 3, the extruder is a twin-screw extruder.

  Moreover, in addition to the structure in any one of Claims 1 thru | or 4, the invention of Claim 5 is 1 type, or 2 or more types of inorganic fillers 10-300 with respect to 100 mass parts of said liquid crystalline polyester resins. A part by mass is added.

According to a sixth aspect of the present invention, a screw is provided in the barrel, a die is attached to the tip of the barrel, a nozzle is formed at the tip of the die, and the shaft of the screw in the internal flow path of the die. An extruder in which a cross-sectional area perpendicular to the direction decreases from the tip of the screw toward the nozzle, the maximum inner diameter of the barrel being D, the distance from the tip of the screw to the outlet of the nozzle being L, the die When the narrowing angle of the internal flow path is θ, the extruder satisfies both of the following relational expressions (1) and (2).
(1) L ≦ D
(2) 0 ° <θ ≦ 45 °

Further, in the invention described in claim 7, in addition to the configuration described in claim 6, there are a plurality of the nozzles, and when the pitch of these nozzles is A and the diameter of each nozzle is DA, the following relational expression ( 3) is satisfied.
(3) 2 ≦ A / DA ≦ 10

  According to the present invention, since the shape and dimensions of the die are regulated, it is possible to suppress the occurrence of strand breakage and enhance the stability of the strand during extrusion molding of the liquid crystal polyester resin pellet. Therefore, it becomes possible to produce the liquid crystal polyester resin pellets stably with a high yield.

It is a front view of the extruder which concerns on Embodiment 1 of this invention. It is a figure which shows the principal part of the extruder shown in FIG. 1, Comprising: (a) is the horizontal sectional view, (b) is a B arrow view of (a), (c) is C- of the barrel of (a). It is sectional drawing by a C line.

Embodiments of the present invention will be described below.
Embodiment 1 of the Invention

  1 and 2 show Embodiment 1 of the present invention. In the first embodiment, a twin screw extruder 1 is used as an example of an extruder.

Hereinafter, the structure of the biaxial extruder 1 and the manufacturing method of a liquid crystal polyester resin pellet are demonstrated in order.
<Configuration of twin screw extruder>

  As shown in FIG. 1, the twin-screw extruder 1 according to the first embodiment has a support base 2, and a barrel 3 is placed on the support base 2. As shown in FIG. 2, the barrel 3 has a block-shaped main body 3a. An internal flow path 3e having a gourd cross section is formed in the main body 3a so as to penetrate in the horizontal direction (left and right direction in FIG. 1). Yes. Further, as shown in FIG. 1, the main body 3a has a liquid crystal polyester supply port 3b, an inorganic filler supply port 3c, and two vent ports 3d in such a manner that the upper space of the barrel 3 and the internal flow path 3e communicate with each other. Is formed. Here, the liquid crystal polyester supply port 3b is near the most upstream part of the main body 3a, the inorganic filler supply port 3c is downstream of the liquid crystal polyester supply port 3b, and the two vent ports 3d are inorganic with the liquid crystal polyester supply port 3b. It is provided between the filler supply port 3c and in the vicinity of the most downstream portion of the main body 3a. Further, as shown in FIG. 2A, two screws 6 are horizontally installed in the internal flow path 3e so as to be parallel to each other.

  As shown in FIG. 1, a motor 4 is attached to the rear of the barrel 3. By driving the motor 4, the two screws 6 can be rotated at a predetermined rotational speed.

  On the other hand, a die 5 is attached to the tip of the barrel 3, as shown in FIGS. The die 5 has a block-shaped main body 5a, and an internal flow path 5d is formed in the main body 5a in the horizontal direction (FIG. 2 (a) left-right direction) so as to communicate with the internal flow path 3e of the barrel 3. ing. In addition, five round-hole nozzles 5b are formed at the tip of the main body 5a so as to communicate the front space of the die 5 and the internal flow path 5d. These nozzles 5b are arranged in a straight line along the horizontal direction at a predetermined pitch (distance between the centers of two adjacent nozzles 5b) A, and each nozzle 5b has a predetermined diameter DA. ing.

  Here, as shown in FIG. 2A, the internal flow path 5d of the die 5 has a narrowing angle θ exceeding 0 ° and not more than 45 ° (0 ° <θ ≦ 45 °). The cross-sectional area perpendicular to the axial direction 6 (directions of arrows E and F) gradually decreases from the tip 6a of the screw 6 toward the nozzle 5b. The distance L from the tip 6a of the screw 6 to the outlet 5c of the nozzle 5b is equal to or smaller than the maximum inner diameter D of the barrel 3 (L ≦ D). Further, the value obtained by dividing the pitch A of the nozzle 5b by the diameter DA of the nozzle 5b is 2 or more and 10 or less (2 ≦ A / DA ≦ 10).

  Further, the outermost nozzle 5b of the die 5 is formed so as to be continuous with the inner wall surface of the die 5 without a step as shown in FIG.

  The barrel 3 and the die 5 are provided with a heater (not shown), and the heater can heat the internal flow path 3e of the barrel 3 and the internal flow path 5d of the die 5 to a predetermined temperature. .

Further, as shown in FIG. 1, a cooling water tank 7 is installed in front of the die 5, and a pelletizer 9 is installed in front of the cooling water tank 7.
<Method for producing liquid crystal polyester resin pellets>

  When liquid crystal polyester resin pellets are manufactured using the twin-screw extruder 1 having the above-described configuration, the following procedure is used.

  First, the barrel 3 and the die 5 are held at a predetermined temperature (for example, 340 ° C.), and the motor 4 is driven to rotate the two screws 6 at a predetermined rotation speed (for example, 600 rpm). At this time, the temperature of the barrel 3 and the die 5 and the rotation speed of the screw 6 are appropriately set according to the characteristics of the liquid crystal polyester resin described below.

  In this state, the liquid crystal polyester resin is introduced from the liquid crystal polyester supply port 3b of the barrel 3 and the inorganic filler is introduced from the inorganic filler supply port 3c. Supply to path 3e. Then, the liquid crystal polyester resin and the inorganic filler are melted and kneaded in the internal flow path 3e of the barrel 3 to produce a liquid crystal polyester resin composition, and the nozzle 5b of the die 5 forwards the die 5 (that is, the cooling water tank 7 side). ) To be a string-like strand S.

The liquid crystal polyester resin used here is a polyester called a thermotropic liquid crystal polymer, and forms a melt that exhibits optical anisotropy at 450 ° C. or lower. Examples of the liquid crystal polyester resin include those shown in the following (a) to (d).
(A): What is obtained by polymerizing aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol in combination.
(B): obtained by polymerizing plural kinds of aromatic hydroxycarboxylic acids.
(C): A product obtained by polymerizing an aromatic dicarboxylic acid and an aromatic diol in combination.
(D): A product obtained by reacting a crystalline polyester such as polyethylene terephthalate with an aromatic hydroxycarboxylic acid.

  In addition, regarding the production of the liquid crystalline polyester resin, it is also possible to use those ester-forming derivatives instead of the above-mentioned aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid or aromatic diol. If it uses, there exists an advantage that manufacture of a liquid crystal polyester resin becomes easier.

  Examples of ester-forming derivatives of aromatic hydroxycarboxylic acids and aromatic dicarboxylic acids having a carboxyl group in the molecule include those in which this carboxyl group is converted to a highly reactive group such as a haloformyl group or an acyloxycarbonyl group, The thing which forms ester with alcohols and ethylene glycol so that a carboxyl group may produce | generate polyester by transesterification is mentioned. In addition, as an ester-forming derivative of an aromatic hydroxycarboxylic acid or aromatic diol having a phenolic hydroxyl group (phenolic hydroxyl group) in the molecule, for example, this phenolic hydroxyl group generates a polyester by a transesterification reaction. Thus, the thing which forms ester with lower carboxylic acid is mentioned.

  Furthermore, the aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid or aromatic diol described above has a halogen atom such as a fluorine atom or a chlorine atom in its aromatic ring; An alkyl group such as a group; an aryl group such as a phenyl group may be substituted.

Examples of the structural unit derived from the aromatic hydroxycarboxylic acid constituting the liquid crystal polyester resin include those shown in Chemical formula 1.

  The structural unit may have a halogen atom, an alkyl group, or an aryl group as a substituent.

As a structural unit derived from the aromatic dicarboxylic acid which comprises liquid crystal polyester resin, what is shown to Chemical formula 2 is mentioned, for example.

  The structural unit may have a halogen atom, an alkyl group, or an aryl group as a substituent.

Examples of the structural unit derived from the aromatic diol constituting the liquid crystal polyester resin include those shown in Chemical formula 3.

  The structural unit may have a halogen atom, an alkyl group, or an aryl group as a substituent.

Here, suitable liquid crystal polyester resins include those having a combination of structural units shown in the following (a) to (h).
(A): A combination of (A ₁ ), (B ₁ ) and (C ₁ ), or a combination of (A ₁ ), (B ₁ ), (B ₂ ) and (C ₁ ).
(B): A combination of (A ₂ ), (B ₃ ) and (C ₂ ), or a combination of (A ₂ ), (B ₁ ), (B ₃ ) and (C ₂ ).
(C): A combination of (A ₁ ) and (A ₂ ).
(D) in each combination of the structural units of :( a), which is replaced a part or all of (A ₁₎ with (A _2).
(E) in each of the combinations of the structural units of :( a), those replaced with (B ₁₎ a part of or the whole (B _3).
(F) in each of the combinations of the structural units of :( a), those replaced by (C ₁₎ of some or all (C _3).
(G) in each of the combinations of the structural units of :( b), those replaced with a part or all of _{(A 2) (A 1)} .
(H) the combination of the structural units of :( c), plus (B ₁₎ and (C _2).

As the liquid crystal polyester resin used in the present invention as in the above (a) to (h), the structural unit derived from the aromatic hydroxycarboxylic acid has (A ₁ ) and / or (A ₂ ), As a structural unit derived from an aromatic dicarboxylic acid, it has at least one selected from the group consisting of (B ₁ ), (B ₂ ) and (B ₃ ), and as a structural unit derived from an aromatic diol, (C Those having at least one selected from the group consisting of ₁ ), (C ₂ ) and (C ₃ ) are preferred. As described above, these structural units may have a substituent on the aromatic ring, but when the obtained liquid crystal polyester resin requires better heat resistance, the structural unit may have a substituent. It is desirable not to have.

  As a method for producing the liquid crystal polyester resin, various known methods can be adopted, but a method for producing a liquid crystal polyester resin as proposed by the present applicant in Japanese Patent Application Laid-Open No. 2004-256673 is preferable.

  The liquid crystal polyester resin preferably has a flow start temperature of 200 ° C. or higher. When the flow start temperature of the liquid crystal polyester resin is 200 ° C. or higher, it becomes possible to obtain liquid crystal polyester resin pellets having excellent heat resistance. This flow initiation temperature is when a heated melt is extruded from a nozzle at a heating rate of 4 ° C./min under a load of 9.8 MPa using a capillary rheometer having a nozzle with an inner diameter of 1 mm and a length of 10 mm. The temperature at which the melt viscosity is 4800 Pa · s. This flow initiation temperature is an index representing the molecular weight of a liquid crystal polyester resin (for example, Naoyuki Koide, “Liquid Crystal Polymer—Synthesis / Molding / Application—”, pages 95-105, CMC, issued June 5, 1987). See).

In order to obtain liquid crystal polyester resin pellets excellent in heat resistance, the liquid crystal polyester resin preferably contains at least 30 mol% of the repeating structural unit represented by the above formula (A ₁ ).

  On the other hand, the inorganic filler added to such a liquid crystal polyester resin is not particularly limited, for example, glass fiber, carbon fiber, metal fiber, alumina fiber, boron fiber, titanate fiber, wollastonite, asbestos, Fibrous or needle-like reinforcing materials such as silica alumina fibers, aluminum borate whiskers, titanium oxide whiskers; silicon dioxide, calcium carbonate, alumina, aluminum hydroxide, kaolin, talc, clay, mica, glass flakes, glass beads, Hollow glass beads, dolomite, various metal powders, barium sulfate, potassium titanate, calcined gypsum, graphite, powders such as silicon carbide and silicon nitride, plate-like and other inorganic powder fillers are listed. Species or two or more can be used.

  In addition, it is preferable that the shape of this inorganic filler is fiber shape or plate shape. If the inorganic filler is fibrous or plate-like, liquid crystal polyester resin pellets can be stably produced without causing strand breakage at the outlet 5c of the nozzle 5b of the die 5. When the inorganic filler is fibrous, the average fiber diameter is preferably 0.1 to 30 μm, and the average fiber length is preferably 1 to 500 μm. When the average fiber diameter of the inorganic filler is less than 0.1 μm, the handleability is lowered. Conversely, when the average fiber diameter of the inorganic filler exceeds 30 μm, the strength is lowered. Further, if the average fiber length of the inorganic filler is less than 1 μm, the strength tends to be insufficient, and conversely, if the average fiber length of the inorganic filler exceeds 500 μm, the discharge of the strand S tends to be unstable. It is in.

  In addition, along with the production of such a liquid crystal polyester resin composition, gas and moisture are generated in the internal flow path 3e of the barrel 3, and since this gas and moisture are degassed from the two vent ports 3d to the outside of the barrel 3. The liquid crystal polyester resin composition can be smoothly extruded.

  Next, after the strand S is guided to the cooling water tank 7 and cooled with water, the strand S is cut with a predetermined length (for example, 3 cm) while being wound by the pelletizer 9. Then, a liquid crystal polyester resin pellet is obtained. In addition, as a magnitude | size of this liquid crystal polyester resin pellet, the average diameter is 0.1-10 mm, Preferably it is 1-5 mm. The aspect ratio (diameter / length ratio) of the liquid crystal polyester resin pellet is 0.1 to 10 times, preferably 0.2 to 3 times, and particularly preferably 0.5 to 2 times.

At this time, the nozzle 5b of the die 5 is controlled so that the shear rate γ of the liquid crystal polyester resin is 500 to 5000 s ⁻¹ . The shear rate γ of the liquid crystal polyester resin is such that the discharge amount (kg / h) per unit time of the liquid crystal polyester resin composition is Q, the specific gravity of the liquid crystal polyester resin composition is ρ, the number of nozzles is n, the nozzle diameter ( mm) is DA, and the circumference is π, it can be expressed as γ = (80000/9) · (Q / ρ · n · π · DA ³ ).

By doing so, the strand S is difficult to cut, and at the same time, it becomes easy to stably take up the strand S. On the other hand, when the shear rate γ of the liquid crystal polyester resin is less than 500 s ⁻¹ , the strand S tends to be easily cut. On the other hand, when the shear rate γ of the liquid crystal polyester resin exceeds 5000 s ⁻¹ , it tends to be difficult to stably take up the strand S. This shear rate γ of the liquid crystal polyester resin is preferably 1000 s ^-1 or more, more preferably 1500s ^-1 or more.

  Moreover, it is preferable that the mixing ratio of liquid crystalline polyester resin and an inorganic filler shall be 10-300 mass parts of 1 type, or 2 or more types of inorganic fillers with respect to 100 mass parts of liquid crystalline polyester resins. By doing so, it becomes possible to stably produce the liquid crystal polyester resin pellets without causing strand breakage at the outlet 5c of the nozzle 5b while improving the mechanical strength of the liquid crystal polyester resin pellets by the inorganic filler. .

  Moreover, since the distance L from the front-end | tip 6a of the screw 6 to the exit 5c of the nozzle 5b is below the largest internal diameter D of the barrel 3 (L <= D), as for the twin-screw extruder 1, as above-mentioned, The front dead space is reduced, and the liquid crystal polyester resin composition staying in the internal flow path 5d of the die 5 can be reduced. As a result, strand breakage can be prevented from occurring at the outlet 5c of the nozzle 5b, and the strand S can be stably taken up. On the other hand, if the distance L from the tip 6a of the screw 6 to the outlet 5c of the nozzle 5b exceeds the maximum inner diameter D of the barrel 3 (L> D), the dead space in front of the screw 6 becomes large, and the die The liquid crystal polyester resin composition staying in the internal flow path 5d of 5 increases. As a result, the liquid crystal polyester resin composition in the die 5 is decomposed to generate gas, and the strand S is easily cut at the outlet 5c of the nozzle 5b. As described above, when L ≦ D, that is, L / D ≦ 1, the above-described effects are exhibited. However, preferably 0.2 ≦ L / D ≦ 0.8, and more preferably 0.2 ≦ L / D ≦ 0.5.

  Further, as described above, since the narrowing angle θ of the internal flow path 5d of the die 5 is greater than 0 ° and equal to or less than 45 ° (0 ° <θ ≦ 45 °), the twin-screw extruder 1 has an outlet of the nozzle 5b. Liquid crystal polyester resin pellets can be stably produced without causing strand breakage in 5c. On the other hand, when the narrowing angle θ is 0 ° or less, the strand S discharged from the outermost nozzle 5b is not stable, and the strand may be broken. On the other hand, when the narrowing angle θ exceeds 45 °, a staying part of the liquid crystal polyester resin composition is generated at the boundary between the barrel 3 and the die 5, and there is a possibility that strand breakage is induced.

  In addition, as described above, the outermost nozzle 5b of the die 5 is continuous with the inner wall surface of the die 5 without a step, so that the stay in the die 5 can be further reduced.

  Moreover, since the value which remove | divided the pitch A of the nozzle 5b by the diameter DA of the nozzle 5b is 2-10 as the twin-screw extruder 1 was mentioned above (2 <= A / DA <= 10), the nozzle 5b The liquid crystal polyester resin pellets can be stably produced without causing strand breakage at the outlet 5c. On the other hand, when the value obtained by dividing the pitch A of the nozzle 5b by the diameter DA of the nozzle 5b is less than 2, adjacent strands S are easily welded to each other and strand breakage is likely to occur. On the contrary, when the value obtained by dividing the pitch A of the nozzle 5b by the diameter DA of the nozzle 5b exceeds 10, the dead space between the adjacent nozzles 5b becomes large, and the strand S is not stable. From this viewpoint, the value obtained by dividing the pitch A of the nozzles 5b by the diameter DA of the nozzles 5b is more preferably 5 or less.

Moreover, since the twin-screw extruder 1 is provided with the two screws 6, the liquid crystal polyester resin and the inorganic filler can be uniformly melt-kneaded.
[Other Embodiments of the Invention]

  In the first embodiment described above, the case where the strand S is cooled in the cooling water tank 7 and then cut when the liquid crystal polyester resin pellets are manufactured has been described. However, the strand S can also be water-cooled using water cooling means other than the cooling water tank 7 (for example, a method of applying water flow or mist). Furthermore, instead of such a water cooling method, an air cooling method (such as a mesh conveyor) or an oil cooling method may be adopted. Alternatively, instead of such a cold cut method, a hot cut method in which the strand S is cut without cooling, a mist cut method, or an underwater cut method may be employed.

  Moreover, in Embodiment 1 mentioned above, the dice | dies 5 with which the nozzle 5b of five round holes was located in a straight line along the horizontal direction were demonstrated. However, the shape, number and arrangement of the nozzles 5b are not limited to this, and may be appropriately changed according to the characteristics of the liquid crystal polyester resin composition and the like. For example, fifteen square hole nozzles 5b may be provided in a staggered arrangement (an arrangement in which a plurality of stages are alternately displaced). The nozzle 5b preferably has a shape that narrows from the inlet toward the outlet 5c. Furthermore, it is preferable that the corner of the inlet of the nozzle 5b is chamfered.

  In the first embodiment described above, the barrel 3 in which the two vent ports 3d are provided between the liquid crystal polyester supply port 3b and the inorganic filler supply port 3c and in the vicinity of the most downstream portion of the main body 3a has been described. However, the position and the number of the vent ports 3d are not limited to this, and may be appropriately changed according to the characteristics of the liquid crystal polyester resin composition and the like. The type of the vent port 3d is not particularly limited, and an open vent or a vacuum vent can be adopted. However, a vacuum vent is preferable from the viewpoint of heat resistance. In the case of a vacuum vent, the decompression is usually performed using various pumps such as a water ring pump, a rotary pump, an oil diffusion pump, and a turbo pump.

  Moreover, in Embodiment 1 mentioned above, the case where an inorganic filler was added to liquid crystal polyester resin and the liquid crystal polyester resin composition was produced | generated was demonstrated. However, liquid crystal polyester resins include small amounts of other thermoplastic resins such as polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and modified products thereof, polysulfone, polyether in addition to inorganic fillers One kind or two or more kinds of sulfone, polyether imide and the like, and a small amount of thermosetting resin, for example, phenol resin, epoxy resin, polyimide resin and the like can be added. Furthermore, the liquid crystalline polyester resin includes a mold release improver such as a fluororesin, a higher fatty acid ester compound, and a fatty acid metal soap within a range not impairing the object of the present invention; a colorant such as a dye and a pigment; an antioxidant; Ordinary additives such as heat stabilizers; fluorescent brighteners; ultraviolet absorbers; antistatic agents; surfactants may be added. Further, additives having an external lubricant effect such as higher fatty acid, higher fatty acid ester, higher fatty acid metal salt, and fluorocarbon surfactant may be added to the liquid crystal polyester resin.

  Moreover, in Embodiment 1 mentioned above, in order to obtain the strand S of circular cross-section shape, the case where the die | dye 5 which has the nozzle 5b of a round hole was used was demonstrated. However, it is possible to use a die 5 having a nozzle 5b having various shapes (an elliptical cross section, a polygonal cross section, a star cross section, etc.) according to the cross-sectional shape of the strand S to be manufactured.

  Furthermore, in Embodiment 1 mentioned above, the case where the liquid crystal polyester resin pellet was manufactured using the biaxial extruder 1 was demonstrated. As this twin-screw extruder 1, those of the type such as the same direction rotating 1-3 thread, the different direction rotating parallel axis, the oblique axis or the incomplete meshing screw can be used. This is a double screw extruder. Alternatively, a single screw extruder may be substituted.

Examples of the present invention will be described below. In addition, this invention is not limited to an Example.
<Example 1>

Using Ikegai's twin screw extruder “PCM-30HS”, the temperature of the barrel and the die is kept at 340 ° C., and 100 parts by mass of the liquid crystalline polyester resin and 23 parts by mass of the inorganic filler are placed in the internal flow path of the barrel. The two screws were rotated at a rotational speed of 600 rpm and granulated for 5 hours to obtain liquid crystal polyester resin pellets. The discharge amount per unit time of the liquid crystal polyester resin composition was 50 kg / h. Further, the shear rate γ of the liquid crystal polyester resin was 949 s ⁻¹ .

  This twin screw extruder has a die having four nozzles having a diameter DA of 3 mm and a pitch A of 9 mm, and a value obtained by dividing the distance L from the screw tip to the nozzle outlet by the maximum inner diameter D of the barrel ( L / D) was 0.8, the die narrowing angle θ was 15 °, and the value obtained by dividing the nozzle pitch A by the nozzle diameter DA (A / DA) was 3.

As the liquid crystal polyester resin, a liquid crystal polyester resin (flow) in which the structural units (A ₁ ), (B ₁ ), (B ₂ ), and (C ₁ ) are mixed at a molar ratio of 60: 15: 5: 20, respectively. A starting temperature of 330 ° C. and a density of 1.38 g / cm ³ ) was used. As the inorganic filler, chopped glass fiber “CS03JAPX-1” manufactured by Owens Corning Co., Ltd. was used.
<Example 2>

As a die of a twin screw extruder, a die having a diameter DA of 3 mm, a pitch A of 10.5 mm (and hence A / DA = 3.5), and a narrowing angle θ of 25 ° was used. In the same manner as in Example 1 described above, liquid crystal polyester resin pellets were obtained. The discharge rate per unit time of the liquid crystal polyester resin composition was 50 kg / h as in Example 1. The shear rate γ of the liquid crystal polyester resin was 1898 s ⁻¹ .
<Comparative Example 1>

As a die of a twin screw extruder, except that a die having a diameter DA of 3 mm, a pitch A of 18 mm (and hence A / DA = 6), and a narrowing angle θ of −15 ° was used, In the same manner as in Example 1 described above, liquid crystal polyester resin pellets were obtained. The discharge rate per unit time of the liquid crystal polyester resin composition was 50 kg / h as in Example 1. Further, the shear rate γ of the liquid crystal polyester resin was 759 s ⁻¹ .
<Comparative example 2>

As a die of the twin screw extruder, a die having a diameter DA of 3 mm and a pitch A of 9 mm (thus, A / DA = 3), a die having a narrowing angle θ of 15 °, and each screw is used. The implementation described above, except that the value obtained by dividing the distance L from the tip of the screw to the nozzle outlet by the maximum inner diameter D of the barrel (L / D) is 1.5 by replacing it with a shorter one. In the same manner as in Example 1, liquid crystal polyester resin pellets were obtained. The discharge rate per unit time of the liquid crystal polyester resin composition was 50 kg / h as in Example 1. The shear rate γ of the liquid crystal polyester resin was 1898 s ⁻¹ .
<Evaluation of granulation stability>

For each of Examples 1 and 2 and Comparative Examples 1 and 2, the presence or absence of strand breakage was visually confirmed to evaluate granulation stability. The results are summarized in Table 1.

  As is clear from Table 1, in Comparative Example 1, since the die narrowing angle θ was −15 °, strand breakage occurred frequently at the outermost nozzle. In Comparative Example 2, since the distance L from the tip of the screw to the nozzle outlet was 1.5 times the maximum inner diameter D of the barrel, strand breakage occurred 2 hours after the start of granulation. In contrast, in each of Examples 1 and 2, the die narrowing angle θ is greater than 0 ° and equal to or less than 45 °, and the distance L from the screw tip to the nozzle outlet is the maximum of the barrel. Since the inner diameter was not more than D, in Example 1, strand breakage occurred gradually after 4 hours, and in Example 2, strand breakage did not occur.

  From the above, in Examples 1 and 2, compared to Comparative Examples 1 and 2, the frequency of occurrence of strand breakage was significantly low, resulting in excellent granulation stability.

  The liquid crystal polyester resin pellet of the present invention can be used in a wide range of applications.

  That is, there are no particular limitations on the use of the liquid crystalline polyester resin pellets. For example, in addition to paints and coating materials, connectors, sockets, relay parts, coil bobbins, optical pickups, oscillators, printed wiring boards, computer-related parts Electrical and electronic parts such as IC trays, parts related to semiconductor manufacturing processes such as wafer carriers; VTR, television receivers, irons, vacuum cleaners, refrigerators, rice cookers, lighting fixtures and other household electrical parts; lamp reflectors, Lighting fixture parts such as lamp holders; Acoustic product parts such as compact discs, laser discs (registered trademark) and speakers; Communication equipment parts such as ferrules for optical cables, telephone parts and facsimile parts; Copying machines related to separation nails and heater holders Parts: Gears, gears , Bearings, motor parts and mechanical parts such as cases; microwave cooking pots, cooking utensils and containers such as heat-resistant dishes; insulation materials such as flooring and wall materials, supporting materials such as beams and roofing materials, etc. Civil engineering and building materials; automotive parts, aircraft parts, space equipment parts, radiation facility parts such as nuclear reactors, marine facility parts cleaning jigs, optical equipment parts, valves, pipes, nozzles, medical equipment parts and Examples thereof include medical materials, sensor parts, filters, and membranes.

  In addition, a film-like or sheet-like material processed from the liquid crystal polyester resin pellets and a material processed from them are industrially useful materials, for example, display device parts, electrical insulation films, flexible materials. It is used for applications such as a circuit board film, a packaging film, and a recording medium film. Since liquid crystal polyester resin pellets are excellent in extrusion moldability, they are also useful as coating materials for resin molded products and metal parts, and can be used for coating in various fields such as pipe coating and wire coating.

  Furthermore, fibrous materials such as continuous fibers, short fibers, and pulp processed from liquid crystal polyester resin pellets, and materials processed from them are industrially useful materials such as clothing, heat-resistant heat insulating materials, FRP, and the like. It can be used for applications such as (fiber-reinforced plastic) reinforcing materials, rubber reinforcing materials, ropes, cables, and nonwoven fabrics.

1 ... Two-screw extruder (extruder)
2 …… Supporting base 3 …… Barrel 3a …… Main body 3b …… Liquid crystal polyester supply port 3c …… Inorganic filler supply port 3d …… Vent port 3e …… Internal flow path 4 …… Motor 5 …… Die 5a …… Body 5b …… Nozzle 5c …… Outlet 5d …… Internal flow path 6 …… Screw 6a …… Tip 7… Cooling water tank 9… Pelletizer S …… Strand

Claims (7)

A screw is provided in the barrel, a die is attached to the tip of the barrel, a nozzle is formed at the tip of the die, and a cross-sectional area perpendicular to the axial direction of the screw in the internal flow path of the die is a tip of the screw When producing liquid crystal polyester resin pellets by melt-kneading the liquid crystal polyester resin in the barrel and extruding from the nozzle to the outside of the die using an extruder that decreases toward the nozzle from
When the maximum inner diameter of the barrel is D, the distance from the tip of the screw to the outlet of the nozzle is L, and the narrowing angle of the internal flow path of the die is θ, the extruder has the following relational expression (1) ( 2) A method for producing a liquid crystal polyester resin pellet characterized by satisfying all of the above.
(1) L ≦ D
(2) 0 ° <θ ≦ 45 ° 2. The device according to claim 1, wherein there are a plurality of the nozzles, and when the pitch of these nozzles is A and the diameter of each nozzle is DA, the die satisfies the following relational expression (3). Manufacturing method of liquid crystal polyester resin pellets.
(3) 2 ≦ A / DA ≦ 10 3. The method for producing liquid crystal polyester resin pellets according to claim 1, wherein the liquid crystal polyester resin has a shear rate of 500 to 5000 s ⁻¹ in the nozzle.   The method for producing liquid crystal polyester resin pellets according to any one of claims 1 to 3, wherein the extruder is a twin screw extruder.   The liquid crystal polyester resin according to claim 1, wherein 10 to 300 parts by mass of one or more inorganic fillers are added to 100 parts by mass of the liquid crystal polyester resin. Pellet manufacturing method. A screw is provided in the barrel, a die is attached to the tip of the barrel, a nozzle is formed at the tip of the die, and a cross-sectional area perpendicular to the axial direction of the screw in the internal flow path of the die is a tip of the screw An extruder that decreases from the nozzle toward the nozzle,
When the maximum inner diameter of the barrel is D, the distance from the tip of the screw to the outlet of the nozzle is L, and the narrowing angle of the internal flow path of the die is θ, any of the following relational expressions (1) and (2) Extruder characterized by satisfying
(1) L ≦ D
(2) 0 ° <θ ≦ 45 ° The extruder according to claim 6, wherein there are a plurality of the nozzles, and the following relational expression (3) is satisfied, where A is the pitch of these nozzles and DA is the diameter of each nozzle.
(3) 2 ≦ A / DA ≦ 10

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