JP2018030948A - Liquid crystal polyester composition and resin molded body using the same - Google Patents

Abstract

Disclosed is a liquid crystal polyester composition capable of molding a resin molded article excellent in crack resistance and warpage resistance. A liquid crystal polyester composition comprising a hollow filler and a fibrous filler having a number average fiber length of 20 μm or more and less than 190 μm. [Selection] Figure 1

Description

  The present invention relates to a liquid crystal polyester composition and a resin molded body using the same.

  For example, a CPU socket is known as an electronic component connector. The CPU socket refers to a connector for mounting a CPU (Central Processing Unit) on the electronic circuit board in a detachable form. The CPU socket can be formed of, for example, a resin excellent in fluidity and heat resistance. It is known that liquid crystal polyester is adopted as such a resin. However, when molding using these resins, cracks are likely to occur, and the occurrence of cracks sometimes becomes a problem.

  The CPU socket has a number of pin insertion holes corresponding to each connection pin of the CPU, and forms a lattice. For example, a CPU having about 1000 to 2000 connection pins is known as a desktop product, and a CPU having more than 3000 connection pins is also known as a server product.

  The CPU connection pins are arranged in a matrix, for example, on the bottom surface of the CPU. The pitch of these connection pins tends to decrease as the number of connection pins increases. As the pitch of the connection pins becomes smaller, the pitch of the pin insertion holes also decreases, and the width of the wall separating the pin insertion holes becomes narrower. For this reason, in the CPU socket, as the number of pin insertion holes increases, cracks are likely to occur around the pin insertion holes after reflow heating, and the occurrence of cracks sometimes becomes a problem.

  In addition, the CPU socket tends to increase in size in order to increase the number of connection pins. As a large-sized CPU socket, for example, a CPU socket for a server having a piece length exceeding 70 mm is known. In a large-sized CPU socket, warping after reflow heating due to residual stress (internal stress) sometimes becomes a problem. Further, warping of a large CPU socket sometimes causes a problem when molding using the above-described resin.

  A composition that can reduce the occurrence of cracks and warpage in a CPU socket is known (for example, Patent Document 1). In Patent Document 1, as a connector forming material, a liquid crystalline polymer, a plate-like inorganic filler, and a fibrous filler having a weight average fiber length of 250 to 600 μm (hereinafter referred to as “long fiber filler”). It is disclosed to use a composite resin composition containing the same. It has been shown that by adding a long fiber filler, a planar connector excellent in performance such as moldability, flatness (flatness), warpage deformation, and heat resistance can be obtained.

JP 2010-003661 A

  However, even when the composite resin composition described in Patent Document 1 is used, the occurrence of cracks and warpage has not been sufficiently reduced. In addition to the above-described connector, cracks and warpage may be a problem in a molded body having a small thickness or a large molded body, as in the case of the connector.

  This invention is made in view of such a situation, Comprising: It aims at providing the liquid crystal polyester composition which can shape | mold the connector excellent in crack resistance and curvature resistance, and a resin molding using the same. To do.

  In order to achieve such an object, the present inventors have studied the composition of the connector forming material and have completed the present invention.

  One embodiment of the present invention provides a liquid crystal polyester composition comprising a hollow filler and a fibrous filler having a number average fiber length of 20 μm or more and less than 190 μm.

  In one embodiment of the present invention, the hollow filler preferably has a number average particle diameter of 5 μm to 100 μm.

  In one embodiment of the present invention, the fibrous filler preferably has a number average fiber diameter of 5 μm to 20 μm.

  In one embodiment of the present invention, the liquid crystal polyester preferably contains the following structural unit in an amount of 30 mol% or more based on all repeating units of the liquid crystal polyester.

In one aspect of the present invention, the volume specific heat at 100 ° C. is preferably at most 1.0 J / cm ³ K or more 3.0J / cm ³ K.

  One aspect of the present invention provides a resin molded body formed of the liquid crystal polyester composition.

  In one aspect of the present invention, the resin molded body is preferably a connector.

  According to one aspect of the present invention, there are provided a liquid crystal polyester composition capable of forming a resin molded article excellent in crack resistance and warpage resistance, and a resin molded article using the same, particularly a connector.

It is a figure which shows the structure of the connector which concerns on embodiment of this invention, (A) is a top view, (B) is AA sectional drawing of (A). It is the elements on larger scale of FIG.

<Resin molding>
The resin molding of this embodiment is formed with the liquid crystal polyester composition mentioned later. Examples of the resin molded body of this embodiment include electrical / electronic parts such as connectors, sockets, relays, coil bobbins, optical pickups, oscillators, computer-related parts, semiconductor manufacturing process-related parts such as IC trays, VTRs, televisions, Home appliance parts such as irons, air conditioners, stereos, vacuum cleaners, refrigerators, rice cookers, lighting fixtures; acoustic product parts such as compact discs, laser discs (registered trademark), speakers, etc .; communications such as telephones, facsimiles, and modems Equipment parts; heater holders and other copiers and printer-related parts; impellers, fan gears, gears, bearings, motor parts and cases, and other mechanical parts; microwave cooking pots, heat-resistant dishes, and other cooking utensils; Thermal insulation such as flooring and wall materials, soundproofing materials, supporting materials such as beams and pillars, building materials such as roofing materials, or soil Building material; aircraft parts, parts for space equipment; Reactor radiation facilities member, offshore facilities member, cleaning jig, pipes, nozzles such, sensors, parts, sporting goods, and leisure goods and the like. As the resin molded body formed of the liquid crystal polyester composition, a connector is particularly preferable. This is because the effect of improving warpage and cracks is noticeable because there is a molded portion (see the minimum thickness portion 201 in FIG. 2 described later) in which the thickness of the connector is very small.

<Connector>
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2, taking as an example the case where the connector is a CPU socket.

  1A and 1B are views showing the structure of a connector according to the present embodiment, in which FIG. 1A is a plan view and FIG. FIG. 2 is an enlarged view of a portion indicated by B in FIG.

  As shown in FIGS. 1 and 2, the connector 100 of the present embodiment has a plate shape with a square plane and has a square opening 101 at the center. The outer peripheral portion and the inner peripheral portion of the connector 100 are formed with an outer frame portion 102 and an inner frame portion 103 with the back surface formed in a convex shape. In addition, in the region surrounded by the outer frame portion 102 and the inner frame portion 103, 2544 pin insertion holes 104 are provided in a matrix. The pin insertion hole 104 is formed so that the horizontal cross section is a square. As a result, the portion separating the pin insertion holes 104, that is, the shape of the minimum thickness portion 201 is a lattice shape as a whole.

  The external dimensions of the connector 100 are 72 mm × 72 mm, and the dimensions of the opening 101 are 28 mm × 28 mm. The thickness of the connector 100 is 5 mm in the outer frame portion 102 and the inner frame portion 103, and 3 mm in the region surrounded by these frame portions 102 and 103. The pin insertion hole 104 has a size of 0.6 mm × 0.6 mm and a pitch of 1 mm. Further, the width of the minimum thickness portion 201 is 0.33 mm.

  The connector of this embodiment is one of the resin molded bodies described above, and is formed by an injection molding method using a liquid crystal polyester composition described later. Hereinafter, the liquid crystal polyester composition according to the present embodiment will be described in detail.

<Liquid crystal polyester composition>
[Liquid crystal polyester]
The liquid crystal polyester of this embodiment is one of the thermotropic liquid crystal polymers. The thermotropic liquid crystal polymer forms an anisotropic melt at a temperature of 400 ° C. or lower. The liquid crystal polyester is preferably obtained by polymerizing an aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid and an aromatic diol.

  In order to more easily produce a liquid crystal polyester, it is also possible to polymerize after forming a part of raw material monomers such as aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol into ester-forming derivatives. .

  Examples of ester-forming derivatives include the following.

  Examples of the ester-forming derivative include those having a carboxyl group in the molecule, such as aromatic hydroxycarboxylic acid and aromatic dicarboxylic acid. Examples of such ester-forming derivatives include those obtained by converting a carboxyl group into a highly reactive acid halogen group or acid anhydride group, or an ester that generates a polyester by transesterification. There are things.

  Furthermore, examples of the ester-forming derivative include those having a phenolic hydroxyl group such as aromatic hydroxycarboxylic acid and aromatic diol. Examples of such ester-forming derivatives include those in which a phenolic hydroxyl group is converted to an ester to produce a polyester by a transesterification reaction.

  A method for producing a liquid crystal polyester using such an ester-forming derivative will be described later.

  Hereinafter, specific examples of the structural unit of the liquid crystal polyester according to the present embodiment will be described.

Examples of the structural unit derived from the aromatic hydroxycarboxylic acid include the following. As will be described later, in the present embodiment, a case where the structural units (A ₁ ) and (A ₂ ) are used will be described.

  In these structural units, a part of hydrogen atoms in the aromatic ring may be substituted with a substituent selected from a halogen atom, an alkyl group and an aryl group.

The following structural units are derived from aromatic dicarboxylic acids. As will be described later, in the present embodiment, a case where the structural units (B ₁ ), (B ₂ ), and (B ₃ ) are used will be described.

  In these structural units, a part of hydrogen atoms in the aromatic ring may be substituted with a substituent selected from a halogen atom, an alkyl group and an aryl group.

The following structural units are derived from aromatic diols. As will be described later, in the present embodiment, a case where the structural units (C ₁ ) and (C ₃ ) are used will be described.

  In these structural units, a part of hydrogen atoms in the aromatic ring may be substituted with a substituent selected from a halogen atom, an alkyl group and an aryl group.

  In addition, these structural units may contain a fluorine atom, a chlorine atom, or a bromine atom as a substituent of a halogen atom. Moreover, as a substituent of the alkyl group, a lower alkyl group having about 1 to 4 carbon atoms such as a methyl group, an ethyl group, or a butyl group may be included. Moreover, a phenyl group etc. may be included as a substituent of an aryl group.

  Next, a preferred combination of the above structural units will be described.

In this embodiment, it is preferable to use the structural unit of the liquid crystal polyester described above in a combination shown in any one of the following [a] to [f].
[A]: A combination of (A ₁ ), (B ₁ ) or (B ₂ ) or both, and (C ₁ ) [b]: A combination of (A ₁ ) and (A ₂ ) [c]: in combination with the [a], a part of _{(a 1)} are replaced by _{(a 2)} [d]: replaced by the combination of the above [a], a part of _{(B 1) (B 3)} those were [e]: in the combination of the above [a], are replaced by a part of _{(C 1) (C 3)} [f]: the combination of the [b] _{(B 1)} and _(C 1) Plus

Among these combinations [a] to [f], the combination [a] is a structural unit derived from parahydroxybenzoic acid (corresponding to the above structural unit (A ₁ )), and 4,4′-dihydroxy. A structural unit derived from biphenyl (corresponding to the structural unit (C ₁ ) described above), a structural unit derived from terephthalic acid and / or a structural unit derived from isophthalic acid (the structural unit (B ₁ ) described above and / Or (corresponding to (B ₂ )) is particularly preferred. Further, in this combination, the molar ratio (C ₁ ) / (A ₁ ) is preferably 0.2 or more and 1.0 or less, and the molar ratio {(B ₁ ) + (B ₂ )} / ( C ₁ ) is preferably 0.9 or more and 1.1 or less. In addition, the molar ratio (B ₂ ) / (B ₁ ) is preferably greater than 0 and 1 or less, and more preferably greater than 0 and 0.3 or less.

The liquid crystal polyester, the structural unit A _1, preferably contains 30 mol% or more based on all repeating units of the liquid crystal polyester.

  The flow start temperature of the liquid crystal polyester according to this embodiment is preferably 270 ° C to 400 ° C, and more preferably 280 ° C to 380 ° C. When the flow start temperature is in such a range, the liquid crystal polyester composition has good fluidity and heat resistance (solder resistance when the molded body is an electronic component such as a socket). It is. Furthermore, when the flow start temperature is in the above range, thermal degradation is less likely to occur when melt molding is performed to obtain a molded body from liquid crystal polyester.

In this embodiment, the flow start temperature is “a capillary rheometer equipped with a nozzle having an inner diameter of 1 mm and a length of 10 mm and a heating rate of 4 ° C./min under a load of 9.8 MPa (100 Kg / cm ² ). The temperature at which the melt viscosity shows 4800 Pa · sec (ie, 48000 poise) when the heated melt of liquid crystalline polyester is extruded from this nozzle is defined as Such a definition is well known to those skilled in the art as a measure of the molecular weight of liquid crystal polyester (for example, Naoyuki Koide, “Liquid Crystal Polymer—Synthesis / Molding / Application—”, pages 95-105, CMC, 1987). (See June 5 issue).

The liquid crystal polyester composition of the present embodiment, the volume specific heat at 100 ° C. is preferably at most 1.0 J / cm ³ K or more 3.0J / cm ³ K. In this specification, the volume specific heat of the liquid crystal polyester composition is calculated based on the following formula from the specific heat capacity (unit: J / gK) measured according to JIS K7123: 2012 and the density of the liquid crystal polyester composition. Value.
Volume specific heat (J / cm ³ K) = specific heat capacity (J / g K) × density (g / cm ³ )

  As the specific heat capacity of the liquid crystal polyester composition, a value measured by a differential scanning calorimeter “DSC-50” manufactured by Shimadzu Corporation was adopted. On the other hand, as the density of the liquid crystal polyester composition, a value measured with a solid specific gravity meter “ASG-320K” manufactured by Kanto Major Co., Ltd. was adopted.

  In the present embodiment, the volume specific heat of the liquid crystal polyester composition means a heat capacity per unit volume that is an index of a cooling rate. There is a correlation between the volume specific heat of the liquid crystal polyester composition described later and the volume specific heat of the resin molded body, and the smaller the volume specific heat of the liquid crystal polyester composition, the more efficiently it can be cooled during molding. Reducing the volume specific heat of the liquid crystal polyester composition will be described later.

[Hollow filler]
The liquid crystal polyester composition of the present embodiment includes a hollow filler and a fibrous filler.

  The material of the hollow filler used in the present embodiment is not particularly limited, and examples thereof include inorganic materials such as glass, silica, and alumina, and organic materials such as urea resin and phenol resin.

  The hollow filler may be two or more kinds of mixed materials or two or more kinds of lightweight functional fillers as necessary. The lightweight functional filler is a filler having a space inside for the purpose of weight reduction. Examples of lightweight functional fillers include porous ceramic particles, expandable particles, and hollow particles. Among these, the material of the hollow filler is preferably glass from the viewpoint of heat resistance and strength. That is, hollow particles called glass balloons are preferably used as the hollow filler.

  By adding the hollow filler, the volume specific heat of the liquid crystal polyester composition can be reduced. In the conventional liquid crystal polyester composition, a part that is easily cooled and a part that is difficult to cool may be formed due to the structure of the mold used for injection molding. Thereby, the part solidified previously may be destroyed (a crack generate | occur | produces) by shrinkage | contraction of the part solidified later.

  On the other hand, since the liquid crystal polyester composition of this embodiment has a volume specific heat smaller than that of the conventional liquid crystal polyester composition, the liquid crystal polyester composition can be efficiently cooled during injection molding. Therefore, since the whole liquid crystal polyester composition is cooled uniformly, generation | occurrence | production of the crack resulting from the shrinkage | contraction accompanying solidification of a liquid crystal polyester composition can be reduced.

  The number average particle diameter of the hollow filler used in the present embodiment is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 100 μm or less. When the number average particle diameter of the hollow filler is less than 5 μm, not only the orientation of the liquid crystal polymer (liquid crystal polyester) cannot be sufficiently suppressed, but also the porosity of the resin molded body is lowered and the hollow filler The effect of lowering the volume specific heat is not sufficiently exhibited. Therefore, the deformation amount of the warp of the resin molded body may become large.

  Further, when the number average particle diameter of the hollow filler is larger than 100 μm, not only the hollow filler is not uniformly dispersed in the liquid crystal polyester composition, but also the crushing rate is reduced because the pressure resistance of the hollow filler is lowered. May grow. If the distribution of the hollow filler is biased or the crushing rate is increased, the effect of lowering the volume specific heat of the hollow filler is not sufficiently exhibited, so that the occurrence of cracks may not be sufficiently suppressed.

  The thickness of the hollow filler may be a value corresponding to the number average particle diameter of the hollow filler so that the porosity calculated from the density of the hollow filler is about 3/4. When the porosity of the hollow filler is about 3/4, the volume specific heat of the liquid crystal polyester composition can be sufficiently reduced while maintaining the pressure strength.

  As the amount of the hollow filler added is increased, the warpage of the molded product (resin molded body) can be reduced, but on the other hand, the extrudability and moldability of the liquid crystal polyester composition during injection molding are deteriorated. In particular, when the amount of the hollow filler added is too large, the fluidity of the liquid crystal polyester composition is deteriorated, so that a defective filling to the mold is likely to occur.

  On the other hand, if the amount of the hollow sphere filler added is too small, the volume specific heat of the liquid crystal polyester composition does not sufficiently decrease, and sufficient resistance to warpage and cracks may not be obtained.

  Therefore, in this embodiment, the amount of the hollow filler added is preferably 5 parts by mass or more and 80 parts by mass or less, and preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the liquid crystalline polyester. Is more preferable. Moreover, it may exceed 30 mass parts and may be more than 30 mass parts and 50 mass parts or less.

[Fibrous filler]
The material of the fibrous filler used in the present embodiment is not particularly limited, and examples thereof include glass fiber, silica alumina fiber, alumina fiber, and carbon fiber.

  The number average fiber diameter of the fibrous filler used in the present embodiment is preferably 5 μm or more and 20 μm or less. When the number average fiber diameter of the fibrous filler is 5 μm or more, sufficient strength can be imparted to the resin molded body. On the other hand, the larger the number average fiber diameter of the fibrous filler, the smaller the number of fibrous fillers at the same mass. When the number of fibrous fillers decreases, the contact surface area with respect to the liquid crystal polyester decreases. When the number average fiber diameter of the fibrous filler is 20 μm or less, the contact surface area with respect to the liquid crystal polyester when compared with the same mass is sufficient, and sufficient strength can be imparted to the resin molded body.

  The number average fiber length of the fibrous filler is preferably 20 μm or more and less than 190 μm. When the number average fiber length of the fibrous filler is 190 μm or more, the crushing rate of the hollow filler (hollow filler) may increase. This is because the longer the number average fiber length of the fibrous filler, the greater the friction during melt kneading and the higher the shear pressure. If this shear pressure exceeds the pressure resistance of the hollow filler, it is presumed that the hollow filler is easily crushed and the crushing rate of the hollow filler is increased. This not only strengthens the orientation of the liquid crystal polyester composition, but also increases the volume specific heat. In addition, when the resin molded body described later is a molded body having a lattice-like structure like a CPU socket, the longer the fiber length, the more locations where the molten resin becomes laminar in the mold during molding. is there. In the laminar flow portion, the resin and the fibrous filler are easily oriented in the flow direction. Therefore, the anisotropy and non-uniformity of the shrinkage rate of the resin molded body increases. Therefore, the warpage of the resin molded body may not be sufficiently reduced.

  Especially, since the connector of this embodiment has a molding part (refer to the minimum thickness part 201 in FIG. 2) where the thickness of the molded product is very small, warping may be noticeable. Therefore, the number average fiber length of the fibrous filler is preferably less than 190 μm, more preferably 140 μm or less, further preferably 130 μm or less, and further preferably 80 μm or less.

The crushing rate of the hollow filler is a value calculated as follows.
Using the density of the liquid crystal polyester, each filler (including hollow filler and fibrous filler) or the density of additives added as necessary, the theoretical density of the resin molding (from the blending ratio of the liquid crystal polyester composition ( The density when the crushing rate is zero can be calculated. And the crushing rate can be calculated by measuring the density (actual density) of the actual resin molded body and determining the difference between the actual density and the theoretical density.

［式中、αは中空状充填材の配合量（液晶ポリエステル１００質量部に対する質量部）を表す。βは繊維状充填材の配合量（液晶ポリエステル１００質量部に対する質量部）を表す。ρ_０は液晶ポリエステルの密度を表す。ρ_１は中空状充填材の真密度を表す。ρ_２は中空状充填材の材料密度を表す。ρ_３は繊維状充填材の密度を表す。ρは該液晶ポリエステル組成物を射出成形して得られるＡＳＴＭ４号ダンベル試験片の密度を表す。］

[In formula, (alpha) represents the compounding quantity (mass part with respect to 100 mass parts of liquid crystalline polyester) of a hollow filler. β represents the blending amount of the fibrous filler (parts by mass relative to 100 parts by mass of the liquid crystalline polyester). ρ ₀ represents the density of the liquid crystal polyester. [rho ₁ represents the true density of the hollow filler. [rho ₂ represents the material density of the hollow filler. ρ ₃ represents the density of the fibrous filler. ρ represents the density of an ASTM No. 4 dumbbell test piece obtained by injection molding the liquid crystal polyester composition. ]

In the above formula, the theoretical density of the resin molded body is represented by (100 / ρ ₀ ) + (α / ρ ₁ ) + (β / ρ ₃ ). The actual density of the resin molded body is represented by (100 + α + β) / ρ.

  Moreover, it is preferable to set it as 5 to 80 mass parts with respect to 100 mass parts of liquid crystalline polyester, and, as for the addition amount of a fibrous filler, it is more preferable to set it as 10 to 50 mass parts.

  Moreover, it is preferable that the sum total of the addition amount of a hollow filler and a fibrous filler shall be 10 to 100 mass parts with respect to 100 mass parts of liquid crystalline polyester, and shall be 30 to 100 mass parts. More preferably, it is more than 50 mass parts and 95 mass parts or less.

[Plate-like filler]
In addition to the hollow filler and the fibrous filler, a plate-like filler can be added to the liquid crystal polyester composition of the present embodiment. The material of the plate-like filler used in the present embodiment is not particularly limited, and examples thereof include talc, mica, and graphite. Of these, talc and mica are preferred.

  Although the warpage of the molded product (resin molded product) can be further reduced as the amount of the plate-like filler added is increased, the extrudability and moldability of the liquid crystal polyester composition are deteriorated. In particular, if the addition amount of the plate-like filler is too large, the fluidity of the liquid crystal polyester composition is deteriorated, so that filling failure tends to occur. Moreover, since the mechanical strength of a resin molding will fall when there is too much addition amount of a plate-shaped filler, it has a bad influence also on crack resistance. Especially, since the connector of this embodiment has a molded part with a very small thickness of the molded product, cracks may be noticeable. Therefore, the addition amount of the plate-like filler is preferably 5 parts by mass or more and 50 parts by mass or less, and more preferably 5 parts by mass or more and less than 30 parts by mass with respect to 100 parts by mass of the liquid crystalline polyester.

[Other additives]
In the liquid crystal polyester composition of the present embodiment, a release improver such as a fluororesin and a metal soap, a colorant such as a dye and a pigment, an antioxidant, Additives commonly used in injection molded products such as stabilizers, ultraviolet absorbers, antistatic agents, and surfactants may be added.

  Moreover, you may add what has external lubricant effects, such as higher fatty acid, higher fatty acid ester, higher fatty acid metal salt, and a fluorocarbon type surfactant.

  Furthermore, thermoplastic resins other than those mentioned above, such as polyamide, polyester, polyphenylene sulfide, polyether ketone, polycarbonate, polyphenylene ether and modified products thereof, polysulfone, polyether sulfone, polyetherimide, etc., thermosetting resins such as A small amount of phenol resin, epoxy resin, polyimide resin or the like may be added.

<Production method of resin molding>
Next, the manufacturing method of the resin molding using the liquid crystal polyester composition of this embodiment is demonstrated. Hereinafter, a CPU socket that is one of connectors will be described as an example of the resin molded body, and the manufacturing method thereof will be described. However, the present embodiment is not limited to this.

[Production method of liquid crystalline polyester]
Hereinafter, an example of a method for producing the liquid crystal polyester according to the present embodiment will be described.

The liquid crystal polyester of this embodiment is preferably produced by the following acylation step and polymerization step.
[Acylation step]: Acylation of a phenolic hydroxyl group of an aromatic diol and an aromatic hydroxycarboxylic acid with a fatty acid anhydride (for example, acetic anhydride, etc.), ie, an acyl diol acylated product and an aromatic hydroxy Carboxylic acid acylate) is obtained.
[Polymerization step]: By transesterifying the acyl group of the acylated product obtained in the acylation step with the carboxyl group of the acylated product of aromatic dicarboxylic acid and aromatic hydroxycarboxylic acid, the liquid crystalline polyester is polymerized. obtain.

  The acylation step and the polymerization step may be performed in the presence of a heterocyclic organic base compound as shown below.

In the above structural formula, R _{1 to} R ₄ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxymethyl group, a cyano group, or a cyanoalkyl group having 1 to 4 carbon atoms in the alkyl group, A cyanoalkoxy group having 1 to 4 carbon atoms, a carboxyl group, an amino group, an aminoalkyl group having 1 to 4 carbon atoms, an aminoalkoxy group having 1 to 4 carbon atoms, a phenyl group, a benzyl group, and a phenylpropyl group; Or represents a formyl group.

  Among the heterocyclic organic base compounds of the above formula, 1-methylimidazole or 1-ethylimidazole or both are particularly preferable from the viewpoint of availability.

  The amount of the heterocyclic organic base compound used is 0.005 to 5 when the total amount of raw material monomers for the liquid crystal polyester (that is, aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid) is 100 parts by mass. It is preferable to be 1 part by mass. Moreover, it is more preferable to set it as 0.05-0.5 mass part with respect to 100 mass parts of raw material monomers from a viewpoint of improving the color tone and productivity of a molded object (this embodiment resin molding).

  Such a heterocyclic organic base compound may be present at one time during the acylation reaction and the transesterification reaction, and the addition time may be immediately before the start of the acylation reaction or during the acylation reaction. It may be between the acylation reaction and the transesterification reaction. The liquid crystal polyester thus obtained has an advantage that the melt fluidity is very high.

  The amount of fatty acid anhydride (for example, acetic anhydride etc.) used is determined in consideration of the amount of aromatic diol and / or aromatic hydroxycarboxylic acid that are raw material monomers. Specifically, it is preferably 1.0 to 1.2 times equivalent, more preferably 1.0 to 1.15 times equivalent to the total of phenolic hydroxyl groups contained in these raw material monomers. 1.03-1.12 times equivalent, more preferably 1.05-1.1 times equivalent.

  The acylation reaction in the acylation step described above is preferably performed at a temperature range of 130 ° C. to 180 ° C. for 30 minutes to 20 hours, more preferably 140 ° C. to 160 ° C. for 1 to 5 hours.

The aromatic dicarboxylic acid used in the above polymerization step may be present in the reaction system during the acylation step. That is, in the acylation step, the aromatic diol, the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid may be present in the same reaction system.
This is because both the carboxyl group in the aromatic dicarboxylic acid and the optionally substituted substituent are not affected by the fatty acid anhydride. Therefore, after the aromatic diol, the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid are charged to the reactor, the acylation step and the polymerization step may be sequentially performed, or the aromatic diol and the aromatic dicarboxylic acid are used in the reactor. A method may be employed in which the aromatic dicarboxylic acid is further charged into the reactor after the acylation step and the polymerization step is performed. From the viewpoint of simplifying the production process, the former method is preferred.

  The transesterification reaction in the polymerization step described above is preferably carried out while raising the temperature from 130 ° C. to 400 ° C. at a temperature rising rate of 0.1 to 50 ° C./min, and 150 ° C. at a temperature rising rate of 0.3 to 5 ° C./min. More preferably, the temperature is raised from 350C to 350C.

  In addition, when performing the transesterification reaction in the polymerization step, in order to shift the equilibrium, by-product fatty acids (such as acetic acid) and unreacted fatty acid anhydrides (such as acetic anhydride) are evaporated to the outside of the system. It is preferable to distill off. At this time, a part of the distilled fatty acid is refluxed and returned to the reactor, so that the raw material monomer that is evaporated or sublimated with the fatty acid can be condensed or reversely sublimated and returned to the reactor.

  In the acylation reaction in the acylation step and the transesterification reaction in the polymerization step, a batch apparatus or a continuous apparatus may be used as the reactor. Any reaction apparatus can be used to obtain a liquid crystal polyester that can be used in the present embodiment.

  After the polymerization step described above, a step for increasing the molecular weight of the liquid crystal polyester obtained in this polymerization step may be performed. For example, the liquid crystalline polyester obtained in the polymerization step can be cooled and then pulverized to produce a powdered liquid crystalline polyester, and the powder can be heated to increase the molecular weight of the liquid crystalline polyester. .

  Also, pelletized liquid crystal polyester is produced by granulating powdered liquid crystal polyester obtained by cooling and pulverization, and then the pelletized liquid crystal polyester is heated to increase the molecular weight of liquid crystal polyester. May be. High molecular weight using these methods is referred to in the art as solid phase polymerization. Solid phase polymerization is particularly effective as a method for increasing the molecular weight of liquid crystal polyester. By increasing the molecular weight of the liquid crystal polyester, it is possible to obtain the liquid crystal polyester having the above-described suitable flow start temperature.

  The heat treatment in the solid phase polymerization is preferably performed in an inert gas (for example, nitrogen) atmosphere or under reduced pressure. Moreover, it is preferable that the heating time in the case of solid phase polymerization shall be 1 to 20 hours. Furthermore, examples of the apparatus used for this heat treatment include known dryers, reactors, inert ovens, mixers, and electric furnaces.

[Method of blending liquid crystal polyester composition]
The method for blending the raw material components of the liquid crystal polyester composition according to the present embodiment is not particularly limited. For example, the liquid crystalline polyester produced by the above-described method, a hollow filler, a fibrous filler, and a plate-like filler or the additive as necessary (that is, the above-described release material agent, heat stabilizer, etc. ) May be supplied separately to the melt mixer. Further, these raw material components may be premixed using a mortar, Henschel mixer, ball mill, ribbon blender or the like and then supplied to the melt mixer. Furthermore, the pellets prepared by melt-mixing the liquid crystalline polyester and the fibrous filler and the pellets prepared by melt-mixing the liquid crystalline polyester and the hollow filler are mixed at a desired blending ratio. Also good.

[Method for producing resin molded body]
In the present embodiment, a CPU socket that is a resin molded body as shown in FIG. 1 is produced from the liquid crystal polyester composition obtained by such a blending method. For this production, for example, an injection molding method can be used.

  The injection molding in the present embodiment is performed by melting a liquid crystal polyester composition using a known injection molding machine, heating the melted liquid crystal polyester composition to an appropriate temperature, and injecting it into a mold. be able to.

  The temperature at which the liquid crystal polyester composition is heated and melted for injection is preferably [Tp + 10] ° C. or more and [Tp + 50] ° C. or less based on the flow start temperature Tp ° C. of the liquid crystal polyester composition to be used.

  Moreover, it is preferable to select the temperature of a metal mold | die from the range of room temperature (for example, 23 degreeC) -180 degreeC from the point of the cooling rate and productivity of a liquid crystal polyester composition.

  According to the present embodiment, there is provided a liquid crystal polyester composition capable of forming a resin molded article having excellent crack resistance and warpage resistance. Further, by using such a liquid crystal polyester composition, a resin molded body excellent in crack resistance and warpage resistance, particularly a connector is provided.

  Hereinafter, although one Example of this invention is described, this invention is not limited to a present Example. The physical properties of the liquid crystal polyester were measured by the following methods.

<Measurement of flow start temperature of liquid crystal polyester>
Using a flow tester (manufactured by Shimadzu Corp., CFT-500 type), about 2 g of liquid crystalline polyester was filled into a cylinder equipped with a die having a nozzle having an inner diameter of 1 mm and a length of 10 mm, and 9.8 MPa (100 kg / cm ^2). The liquid crystal polyester was melted while being heated at a rate of 4 ° C./min under a load of 4), extruded from a nozzle, and a temperature showing a viscosity of 4800 Pa · s (48000 poise) was measured.

<Production example (Production of liquid crystalline polyester)>
Liquid crystal polyester was produced using the following method.

First, 994.5 g (7.2 mol) of parahydroxybenzoic acid that gives structural unit A ₁ to a reactor equipped with a stirrer, a torque meter, a nitrogen gas introduction pipe, a thermometer, and a reflux condenser, and structural unit C ₁ 446.9 g (2.4 mol) of 4,4′-dihydroxybiphenyl which gives 299.9 g (1.8 mol) of terephthalic acid which gives structural unit B ₁ and 99.7 g of isophthalic acid which gives structural unit B ₂ (0 .6 moles) and 1347.6 g (13.2 moles) of acetic anhydride. At this time, the molar ratio (C ₁ ) / (A ₁ ) is about 0.3, the molar ratio {(B ₁ ) + (B ₂ )} / (C ₁ ) is 1.0, and the molar ratio (B ₂ ) / (B ₁ ) is about 0.3.

  Next, after sufficiently replacing the inside of the reactor with nitrogen gas, 0.18 g of 1-methylimidazole was added, and the temperature was raised from room temperature to 150 ° C. over 30 minutes under a nitrogen gas stream, and this temperature was maintained. And refluxed for 30 minutes. Further, 2.4 g of 1-methylimidazole was added, and the temperature was raised from 150 ° C. to 320 ° C. over 2 hours and 50 minutes while distilling off by-product acetic acid and unreacted acetic anhydride. Thereafter, the time point at which an increase in torque was recognized was regarded as the end of the reaction, and the contents were taken out.

  Subsequently, the solid content (contents) thus obtained was cooled to room temperature and pulverized with a coarse pulverizer. By raising the solid content after pulverization from room temperature to 250 ° C. over 1 hour in a nitrogen atmosphere, further raising the temperature from 250 ° C. to 295 ° C. over 5 hours, and holding at 295 ° C. for 3 hours. Then, solid state polymerization was performed.

  Finally, the product after the solid phase polymerization was cooled to obtain a liquid crystal polyester. The flow starting temperature of the obtained liquid crystal polyester was 327 ° C.

<Examples 1 to 3 and Comparative Examples 1 to 2 (formulation and molding of liquid crystal polyester composition)>
Using the liquid crystal polyester obtained in the production example, three CPU sockets of Examples 1 to 3 and Comparative Examples 1 and 2 were produced as follows.

In the mass composition ratio shown in Table 1, liquid crystal polyester and various fillers were blended, and granulation was performed at a cylinder temperature of 340 ° C. using a twin-screw extruder (“PCM-30” manufactured by Ikekai Tekko Co., Ltd.). By performing, the pellet-form liquid crystal polyester composition (Examples 1-3 and Comparative Examples 1-4) was obtained.
Thereafter, the obtained pellet-like liquid crystal polyester composition was molded under the following molding conditions, so that the connectors of Examples 1 to 3 and Comparative Examples 1 and 2 (corresponding to 2544 pins shown in FIGS. 1 and 2). A model CPU socket (hereinafter referred to as “CPU socket”) was prepared. The various fillers used in this example are as follows. The number average fiber length, number average fiber diameter, and number average particle diameter of various fillers are catalog values.

[Filler]
(1) Hollow filler Glass balloon: S60HS (manufactured by Sumitomo 3M Limited), number average particle diameter 20 μm
(2) Fiber filler Milled glass fiber: EFH75-01 (manufactured by Central Glass Fiber Co., Ltd.), number average fiber length 75 μm, number average fiber diameter 11 μm
: EFH150-01 (manufactured by Central Glass Fiber Co., Ltd.), number average fiber length 150 μm, number average fiber diameter 11 μm
(3) Granular filler Glass beads: EGB731 (manufactured by Potters Barotini Co., Ltd.), number average particle diameter 20 μm

[Molding condition]
Molding machine: “ROBOSHOT S-2000i 30B” manufactured by FANUC
Cylinder temperature: 360 ° C
Mold temperature: 100 ° C
Injection speed: 250mm / sec

<Evaluation of CPU socket>
The seven types of CPU sockets obtained in the examples and comparative examples were evaluated as follows.

(1) Warpage amount (evaluation of warpage resistance)
The obtained CPU socket was set | placed on the glass plane, and the height from the said glass plane was calculated | required about arbitrary 92 points | pieces in the said CPU socket using the flatness measurement module "9030c" made from a cores. Then, the least square plane of the CPU socket was calculated by the least square method using the height of the 92 points. The distance from the least square plane to the highest point among the heights of the 92 points when the height of the least squares plane is translated so as to include the lowest point among the heights of the 92 points. The amount of warpage was calculated.

  Next, the CPU socket was heated from room temperature to 160 ° C. at a temperature rising rate of 2 ° C./second, held at 160 ° C. for 1 minute, and further heated to 250 ° C. at a temperature rising rate of 2 ° C./second. A heat treatment was performed in which the temperature was maintained at 1 ° C. for 1 minute and then gradually cooled to 50 ° C.

  And after cooling this CPU socket after heat processing to room temperature, the amount of curvature was measured like the above. Said operation was performed with respect to the three different test pieces (CPU socket) produced by the Example and the comparative example, respectively, and let the average value be "the amount of curvature after a heating". The results are shown in Table 1.

(2) Crack (Evaluation of crack resistance)
After cooling the CPU socket after the heat treatment to room temperature, the CPU socket after the heat treatment was observed using a digital microscope (“VHX-1000” manufactured by Keyence Corporation, lens “VH-Z25” used). Then, the number of cracks generated in the CPU socket was measured. The same measurement was performed for three CPU sockets, and the average value of the three measured values was defined as the number of cracks. Table 1 shows the number of cracks generated in the CPU sockets of the examples and comparative examples.

(3) Volumetric specific heat First, the specific heat capacity (unit: J / gK) of the liquid crystal polyester compositions used in Examples and Comparative Examples was measured using the method described in JIS K7123: 2012. Specifically, for a test piece (ASTM 4 dumbbell test piece) prepared from the liquid crystal polyester composition used in Examples and Comparative Examples, a differential scanning calorimeter (“DSC-50” manufactured by Shimadzu Corporation) was used. The specific heat capacity (J / gK) at 100 ° C. was measured.

Next, about the test piece (ASTM4 dumbbell test piece) created from the liquid crystal polyester composition used for the Example and the comparative example, a density ((ASG-320K made by Kanto Major Co., Ltd.)) was used for density ( g / cm ³ ) was measured. Using the measured specific heat capacity and density, the volume specific heat was calculated from the following equation. Table 1 shows the volume specific heat in the liquid crystal polyester compositions used in Examples and Comparative Examples.
Volume specific heat (J / cm ³ K) = specific heat capacity (J / g K) × density (g / cm ³ )

(4) Number average fiber length (after pellet molding)
The liquid crystal polyester compositions of Examples 1 to 3 and Comparative Examples 1 to 2 molded into a pellet form with a biaxial extruder were collected in a 2 g crucible. This was treated and ashed at 600 ° C. for 4 hours in an electric furnace to obtain a residue. The residue was dispersed in water, and the number average fiber length of the fibrous filler was measured using a dynamic image analysis method / particle analyzer PITA-3 (manufactured by Seishin Enterprise Co., Ltd.). Filter conditions (analysis conditions) that have an aspect ratio of less than 2, circumscribed rectangular short diameter (fiber diameter) of less than 5 μm and greater than 20 μm, and thinned pixels (fiber length) of less than 20 μm are not fibrous fillers All excluded.

As shown in Table 1, in Example 1, with respect to 100 parts by mass of the resin component (liquid crystal polyester), 33.3 parts by mass of a fibrous filler having a measured number average fiber length of 70 μm, and a hollow filler A liquid crystal polyester composition containing 33.3 parts by mass was used. The volume specific heat of this liquid crystal polyester composition was 1.95 (J / cm ³ K).

  On the other hand, in Comparative Example 2, a liquid crystal containing 33.3 parts by mass of a fibrous filler whose measured value of the number average fiber length is less than 190 μm and 33.3 parts by mass of a granular filler with respect to 100 parts by mass of the liquid crystalline polyester. A polyester composition was used. The CPU socket of Comparative Example 2 had a large amount of warpage after heating and a larger number of cracks than the CPU socket of Example 1. This is considered due to the fact that the volume specific heat of the liquid crystal polyester composition of Comparative Example 2 is higher than the volume specific heat of the liquid crystal polyester composition of Example 1. From the results of Example 1 and Comparative Example 2, it was shown that the volume specific heat of the CPU socket can be reduced by adding the hollow filler.

  Moreover, in the comparative example 1, the liquid crystal polyester composition containing 66.7 mass parts of fibrous filler whose measured value of number average fiber length is less than 190 micrometers with respect to 100 mass parts of liquid crystal polyester was used. Also from the results of Example 1 and Comparative Example 1, it was shown that the amount of warpage after heating of the CPU socket and the number of cracks generated can be reduced by the addition of the hollow filler.

  Thus, according to the present Example, it was shown that the connector with few curvature amount can be provided, suppressing generation | occurrence | production of a crack.

100 connector (CPU socket)
101 Opening 102 Outer frame portion 103 Inner frame portion 104 Pin insertion hole 201 Minimum thickness portion

Claims (7)

  A liquid crystal polyester composition comprising a hollow filler and a fibrous filler having a number average fiber length of 20 μm or more and less than 190 μm.   The liquid crystal polyester composition according to claim 1, wherein the hollow filler has a number average particle diameter of 5 μm to 100 μm.   The liquid crystalline polyester composition according to claim 1, wherein the fibrous filler has a number average fiber diameter of 5 μm or more and 20 μm or less. The liquid crystal polyester composition according to any one of claims 1 to 3, wherein the liquid crystal polyester contains the following structural unit in an amount of 30 mol% or more based on all repeating units of the liquid crystal polyester.

Volume specific heat at 100 ° C. is a liquid crystal polyester composition according to any one of claims 1 to 4 or less 1.0 J / cm ³ K or more 3.0J / cm ³ K.   The resin molding formed with the liquid-crystal polyester composition of any one of Claims 1-5.   The resin molded body according to claim 6 which is a connector.

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