JP6824663B2 - Liquid crystal polyester composition and resin molded product using it - Google Patents

Description

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

As a connector for electronic components, for example, a CPU socket is known. The CPU socket refers to a connector for mounting a CPU (Central Processing Unit, central processing unit) on an electronic circuit board in a detachable manner. The CPU socket can be formed of, for example, a resin having excellent 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, which may cause a problem.

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

The connection pins of the CPU are arranged on the bottom surface of the CPU, for example, in a matrix. The pitch of these connecting pins tends to decrease as the number of connecting pins increases. As the pitch of the connecting 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. Therefore, 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, which may cause a problem.

Further, the CPU socket tends to be large in order to increase the number of connection pins. As a large-sized CPU socket, for example, a CPU socket for a server whose length exceeds 70 mm is known. In a large-sized CPU socket, warpage after reflow heating due to residual stress (internal stress) may become a problem. Further, the warp of the large CPU socket may cause a problem when molding using the above-mentioned resin.

A composition capable of reducing the occurrence of cracks and warpage in a CPU socket is known (for example, Patent Document 1). Patent Document 1 describes liquid crystal polymers, plate-shaped inorganic fillers, and fibrous fillers having a weight average fiber length of 250 to 600 μm (hereinafter referred to as “long fiber fillers”) as materials for forming connectors. It is disclosed to use a composite resin composition containing the same. It has been shown that the addition of a long fiber filler can provide a planar connector having excellent performance such as moldability, flatness (flatness), warpage deformation, and heat resistance.

JP-A-2010-003661

However, even if the composite resin composition described in Patent Document 1 is used, the reduction of cracks and warpage is not sufficient. Further, in addition to the above-mentioned connector, cracks and warpage may occur in a molded body having a small wall thickness, a large molded body, and the like as in the case of the connector.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid crystal polyester composition capable of molding a connector having excellent crack resistance and warpage resistance, and a resin molded product using the same. To do.

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

One aspect of the present invention provides a liquid crystal polyester composition containing 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 aspect of the present invention, the hollow filler preferably has a number average particle size of 5 μm or more and 100 μm or less.

In one aspect of the present invention, the fibrous filler preferably has a number average fiber diameter of 5 μm or more and 20 μm or less.

In one aspect of the present invention, the liquid crystal polyester preferably contains the following structural units in an amount of 30 mol% or more based on all the 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 product formed of the above liquid crystal polyester composition.

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

According to one aspect of the present invention, there is provided a liquid crystal polyester composition capable of molding a resin molded product having excellent crack resistance and warpage resistance, and a resin molded product 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 plan view, (B) is a cross-sectional view of AA of (A). It is a partially enlarged view of FIG. 1 (A).

<Resin molded product>
The resin molded product of the present embodiment is formed of a liquid crystal polyester composition described later. Examples of the resin molded body of the present embodiment include electrical and electronic parts such as connectors, sockets, relays, coil bobbins, optical pickups, oscillators, computer-related parts, and semiconductor manufacturing process-related parts such as IC trays; VTRs, televisions, and the like. Household electrical appliances parts such as irons, air conditioners, stereos, copiers, refrigerators, rice cookers, lighting fixtures, etc .; Acoustic product parts such as compact discs, laser discs (registered trademarks), speakers, etc.; Communication of telephones, facsimiles, modems, etc. Equipment parts; Copiers such as heater holders, printing machine related parts; Mechanical parts such as impellers, fan gears, gears, bearings, motor parts and cases; Cooking utensils such as microwave cooking pots, heat-resistant tableware, etc. Insulation and soundproofing materials such as flooring and wall materials, supporting materials such as beams and pillars, building materials such as roofing materials, or civil engineering and building materials; aircraft parts, space equipment parts; radiation facility parts such as reactors, Examples include marine facility parts, cleaning jigs, pipes, nozzles, sensor parts, sporting goods, leisure goods, and the like. As the resin molded body formed of the liquid crystal polyester composition, a connector is particularly suitable. This is because there is a molded portion having a very small wall thickness of the connector (see the minimum wall thickness portion 201 of FIG. 2 described later), so that the effect of improving warpage and cracks is remarkably observed.

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

1A and 1B are views showing a structure of a connector according to the present embodiment, where FIG. 1A is a plan view and FIG. 1B is a sectional view taken along the line AA of FIG. 1A. Further, FIG. 2 is an enlarged view of the portion shown by B in FIG. 1 (A).

As shown in FIGS. 1 and 2, the connector 100 of the present embodiment has a square plate shape in a plane and has a square opening 101 in the center. The outer peripheral portion and the inner peripheral portion of the connector 100 are formed so that the back surface is convex, and constitutes the outer frame portion 102 and the inner frame portion 103. Further, in the area 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 square. As a result, the shape of the portion separating the pin insertion holes 104, that is, the minimum wall thickness portion 201, becomes a grid 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 size of the pin insertion hole 104 is 0.6 mm × 0.6 mm, and the pitch is 1 mm. The width of the minimum wall 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 the present 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 addition, in order to more easily produce the liquid crystal polyester, it is also possible to polymerize a part of the raw material monomers such as aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol after converting them into ester-forming derivatives. ..

Examples of the ester-forming derivative 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. As such an ester-forming derivative, a carboxyl group is converted into a highly reactive acid halogen group, an acid anhydride, or the like, or the carboxyl group is converted into an ester that produces polyester by a transesterification reaction. There are things.

Further, examples of the ester-forming derivative include those having a phenolic hydroxyl group, such as aromatic hydroxycarboxylic acid and aromatic diol. As such an ester-forming derivative, there is one in which a phenolic hydroxyl group is converted into 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.

Structural units derived from aromatic hydroxycarboxylic acids include the following. As will be described later, in this embodiment, the case where the structural units (A ₁ ) and (A ₂ ) are used will be described.

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

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

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

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

In these structural units, a part of the hydrogen atom 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. Further, as the substituent of the alkyl group, a lower alkyl group having about 1 to 4 carbon atoms such as a methyl group, an ethyl group and a butyl group may be contained. Further, a phenyl group or the like may be contained as a substituent of the aryl group.

Next, a suitable combination of the above-mentioned structural units will be described.

In the present embodiment, it is preferable to use the above-mentioned structural unit of the liquid crystal polyester in the combination shown in any of the following [a] to [f].
[A]: Combination of (A ₁ ) and (B ₁ ) or (B ₂ ) or both with (C ₁ ): 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) Added

Among these combinations [a] to [f], the combination [a], a structural unit derived from parahydroxybenzoic acid (corresponding to the above-mentioned 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 (structural unit (B ₁ ) described above) and / Or a liquid crystal polyester composed of a combination with (corresponding to (B ₂ )) is particularly preferable. 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 )} / ( It is preferable that C ₁ ) is 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 even more preferably greater than 0 and 0.3 or less.

The liquid crystal polyester preferably contains the structural unit A ₁ in an amount of 30 mol% or more based on all the repeating units of the liquid crystal polyester.

The flow start temperature of the liquid crystal polyester according to the present 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 fluidity of the liquid crystal polyester composition is improved, and the heat resistance (when the molded body is an electronic component such as a socket, the solder resistance) is improved. Is. Further, when the flow start temperature is in the above range, thermal deterioration is less likely to occur when performing melt molding for obtaining a molded product from the liquid crystal polyester.

In this embodiment, the flow start temperature is set to "a capillary rheometer having a nozzle having an inner diameter of 1 mm and a length of 10 mm, and a temperature rise rate of 4 ° C./min under a load of 9.8 MPa (100 kg / cm ² ). When the heated melt of liquid crystal polyester is extruded from this nozzle, the melt viscosity is defined as a temperature showing 4800 Pa · sec (that is, 48,000 poise). " 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, edited by Naoyuki Koide, "Liquid Crystal Polymer-Synthesis / Molding / Application-", pp. 95-105, 1987, 1987. See issue on June 5).

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 the present 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 for the liquid crystal polyester composition and the density. Value.
Volume specific heat (J / cm ³ K) = specific heat capacity (J / g K) x density (g / cm ³ )

For the specific heat capacity of the liquid crystal polyester composition, a value measured by a differential scanning calorimetry device "DSC-50" manufactured by Shimadzu Corporation was adopted. On the other hand, the density of the liquid crystal polyester composition adopted the value measured by the solid hydrometer "ASG-320K" manufactured by Kanto Major Co., Ltd.

In the present embodiment, the volume specific heat of the liquid crystal polyester composition means the heat capacity per unit volume which is an index of the 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 product, and the smaller the volume specific heat of the liquid crystal polyester composition, the more efficiently it can be cooled during molding. The reduction of 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 contains 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 a mixed material of two or more kinds, or may be a lightweight functional filler of two or more kinds, if necessary. A lightweight functional filler is a filler having an internal space for the purpose of weight reduction. Examples of the lightweight functional filler include porous ceramic particles, foamable particles, hollow particles and the like. Among these, glass is preferable as the material of the hollow filler from the viewpoint of heat resistance and strength. That is, hollow particles, so-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, due to the structure of the mold used for injection molding, a portion that is easily cooled and a portion that is difficult to be cooled may be formed. As a result, the portion solidified earlier may be destroyed (cracking occurs) due to the shrinkage of the portion solidified later.

On the other hand, since the liquid crystal polyester composition of the present embodiment has a smaller volume specific heat than the conventional liquid crystal polyester composition, the liquid crystal polyester composition can be efficiently cooled at the time of injection molding. Therefore, since the entire liquid crystal polyester composition is uniformly cooled, it is possible to reduce the occurrence of cracks due to shrinkage caused by the solidification of the liquid crystal polyester composition.

The number average particle size 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 size 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 product is lowered, so that the hollow filler The effect of lowering the volume specific heat is not sufficiently exhibited. Therefore, the amount of deformation of the warp of the resin molded product may increase.

Further, when the number average particle size 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 pressure resistance strength of the hollow filler is lowered, so that the crushing rate is high. It can grow. If the distribution of the hollow filler is biased or the crushing rate becomes large, the effect of lowering the volume specific heat of the hollow filler is not sufficiently exerted, 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 converted 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 resistance strength.

The larger the amount of the hollow filler added, the more the warpage of the molded product (resin molded product) can be reduced, but on the other hand, the extrudability and moldability of the liquid crystal polyester composition during injection molding deteriorate. In particular, if the amount of the hollow filler added is too large, the fluidity of the liquid crystal polyester composition deteriorates, so that poor filling in the mold is likely to occur.

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

Therefore, in the present embodiment, the amount of the hollow filler added is preferably 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester, and is preferably 10 parts by mass or more and 50 parts by mass or less. Is more preferable. Further, it may exceed 30 parts by mass, and may exceed 30 parts by mass and 50 parts by mass 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 product. On the other hand, the larger the number average fiber diameter of the fibrous fillers, the smaller the number of fibrous fillers at the same mass. As 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 product.

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 strength of the hollow filler, it is presumed that the hollow filler is likely to be crushed and the crushing rate of the hollow filler is increased. As a result, not only the orientation of the liquid crystal polyester composition is strengthened, but also the volume specific heat is increased. Further, when the resin molded body described later is a molded body having a lattice-like structure such as a CPU socket, the longer the fiber length, the more places where the molten resin becomes a laminar flow in the mold at the time of molding. is there. In the laminar flow portion, the resin and the fibrous filler tend to be oriented in the flow direction. Therefore, the anisotropy / non-uniformity of the shrinkage rate of the resin molded product increases. Therefore, it may not be possible to sufficiently reduce the warp of the resin molded product.

In particular, since the connector of the present embodiment has a molded portion (see the minimum wall thickness portion 201 of FIG. 2) in which the wall thickness of the molded product is very small, warpage may be noticeably observed. 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 the hollow filler and the fibrous filler) or the additive added as needed, the theoretical density of the resin molded product from the blending ratio of the liquid crystal polyester composition (including the hollow filler and the fibrous filler) Density when the crushing rate is zero) can be calculated. Then, the crushing rate can be calculated by measuring the density (actual density) of the actual resin molded product and obtaining 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 the formula, α represents the blending amount of the hollow filler (parts by mass with respect to 100 parts by mass of the liquid crystal polyester). β represents the blending amount of the fibrous filler (parts by mass with respect to 100 parts by mass of liquid crystal polyester). ρ ₀ represents the density of the liquid crystal polyester. ρ ₁ represents the true density of the hollow filler. ρ ₂ represents the material density of the hollow filler. ρ ₃ represents the density of the fibrous filler. ρ represents the density of the ATM4 dumbbell test piece obtained by injection molding the liquid crystal polyester composition. ]

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

The amount of the fibrous filler added is preferably 5 parts by mass or more and 80 parts by mass or less, and more preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

The total amount of the hollow filler and the fibrous filler added is preferably 10 parts by mass or more and 100 parts by mass or less, and 30 parts by mass or more and 100 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester. It is more preferable that the amount exceeds 50 parts by mass and 95 parts by mass or less.

[Plate-shaped 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-shaped 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.

The larger the amount of the plate-shaped filler added, the more the warpage of the molded product (resin molded product) can be further reduced, but on the other hand, the extrudability and moldability of the liquid crystal polyester composition deteriorate. In particular, if the amount of the plate-shaped filler added is too large, the fluidity of the liquid crystal polyester composition deteriorates, so that filling defects are likely to occur. Further, if the amount of the plate-shaped filler added is too large, the mechanical strength of the resin molded product is lowered, which adversely affects the crack resistance. Among them, since the connector of the present embodiment has a molded portion having a very small wall thickness of the molded product, cracks may be noticeably seen. Therefore, the amount of the plate-shaped filler added 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 crystal polyester.

[Other additives]
The liquid crystal polyester composition of the present embodiment contains mold release improvers such as fluororesin and metal soap, colorants such as dyes and pigments, antioxidants, and heat, as long as the effects of the present invention are not impaired. Additives commonly used in injection-molded products, such as stabilizers, UV absorbers, antistatic agents, and surfactants, may be added.

Further, those having an external lubricant effect such as a higher fatty acid, a higher fatty acid ester, a higher fatty acid metal salt, and a fluorocarbon-based surfactant may be added.

Further, thermoplastic resins other than those described above, such as polyamide, polyester, polyphenylene sulfide, polyetherketone, polycarbonate, polyphenylene ether and modified products thereof, polysulphon, polyethersulphon, polyetherimide, etc., and thermosetting resins such as, for example, A small amount of phenol resin, epoxy resin, polyimide resin or the like may be added.

<Manufacturing method of resin molded product>
Next, a method for producing a resin molded product using the liquid crystal polyester composition of the present embodiment will be described. Hereinafter, a CPU socket, which is one of the connectors, will be taken as an example of the resin molded body, and a method for manufacturing the CPU socket will be described, but the present embodiment is not limited to this.

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

The liquid crystal polyester of the present embodiment is preferably produced by the following acylation step and polymerization step.
[Acylation Step]: Acylate (that is, aromatic diol acylated product and aromatic hydroxy) by acylating the phenolic hydroxyl group of aromatic diol and aromatic hydroxycarboxylic acid with a fatty acid anhydride (for example, anhydrous acetic acid). Carboxylic acid acylated product) is obtained.
[Polymerization Step]: A liquid crystal polyester is produced by subjecting the acyl group of the acylated product obtained in the acylation step and the carboxyl group of the acylated product of the aromatic dicarboxylic acid and the aromatic hydroxycarboxylic acid to the ester exchange and polymerizing. obtain.

The acylation step and the polymerization step may be carried out in the presence of a complex cyclic organic base compound as shown below.

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

Among the complex cyclic organic base compounds of the above formula, 1-methylimidazole, 1-ethylimidazole, or both are particularly preferable in terms of availability.

The amount of the heterocyclic organic base compound used is 0.005 to 5 when the total amount of the raw material monomer of the liquid crystal polyester (that is, aromatic dicarboxylic acid, aromatic diol and aromatic hydroxycarboxylic acid) is 100 parts by mass. It is preferable that the amount is 1 part by mass. Further, from the viewpoint of improving the color tone and productivity of the molded product (resin molded product in this embodiment), the content is more preferably 0.05 to 0.5 parts by mass with respect to 100 parts by mass of the raw material monomer.

The 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) used is determined in consideration of the amount of aromatic diol, aromatic hydroxycarboxylic acid, or both of the raw material monomers. Specifically, the equivalent is preferably 1.0 to 1.2 times, more preferably 1.0 to 1.15 times the total equivalent of the phenolic hydroxyl groups contained in these raw material monomers. , 1.03 to 1.12 times equivalent, and particularly preferably 1.05 to 1.1 times equivalent.

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

The aromatic dicarboxylic acid used in the above-mentioned 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 neither the carboxyl group in the aromatic dicarboxylic acid nor the optionally substituted substituent is affected by the fatty acid anhydride. Therefore, a method in which the acylation step and the polymerization step are sequentially performed after charging the aromatic diol, the aromatic hydroxycarboxylic acid and the aromatic dicarboxylic acid into the reactor may be used, or the aromatic diol and the aromatic dicarboxylic acid may be used in the reactor. It is also possible to carry out a polymerization step by further charging an aromatic dicarboxylic acid into a reactor after charging and performing an acylation step. The former method is preferable from the viewpoint of simplifying the manufacturing process.

The transesterification reaction in the above-mentioned polymerization step is preferably carried out while raising the temperature from 130 ° C. to 400 ° C. at a heating rate of 0.1 to 50 ° C./min, and 150 at a heating rate of 0.3 to 5 ° C./min. It is more preferable to carry out while raising the temperature from ° C. to 350 ° C.

In addition, when performing a transesterification reaction in the polymerization step, in order to shift the equilibrium, by-produced 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, by refluxing a part of the distilled fatty acid and returning it to the reactor, the raw material monomer or the like that evaporates or sublimates with the fatty acid can be condensed or reverse sublimated and returned to the reactor.

In the acylation reaction in the acylation step and the transesterification reaction in the polymerization step, a batch device may be used as the reactor, or a continuous device may be used. A liquid crystal polyester that can be used in this embodiment can be obtained by using any of the reaction devices.

After the above-mentioned polymerization step, a step for increasing the molecular weight of the liquid crystal polyester obtained in this polymerization step may be performed. For example, a powdery liquid crystal polyester can be produced by cooling the liquid crystal polyester obtained in the polymerization step and then pulverizing the liquid crystal polyester, and further heating the powder can increase the molecular weight of the liquid crystal polyester. ..

Further, a pellet-shaped liquid crystal polyester is produced by granulating the powdered liquid crystal polyester obtained by cooling and pulverization, and then the pellet-shaped liquid crystal polyester is heated to increase the molecular weight of the liquid crystal polyester. You may. The high molecular weight increase using these methods is referred to as solid phase polymerization in the art. 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 a liquid crystal polyester having the above-mentioned suitable flow start temperature.

The heat treatment for solid-phase polymerization is preferably carried out under an atmosphere of an inert gas (for example, nitrogen) or under reduced pressure. The heating time for solid-phase polymerization is preferably 1 to 20 hours. Further, examples of the apparatus used for this heat treatment include known dryers, reactors, inert ovens, mixers, electric furnaces and the like.

[Formulation method of 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 crystal polyester produced by the above-mentioned method, the hollow filler, the fibrous filler, and if necessary, the plate-like filler or the above-mentioned additive (that is, the above-mentioned release material, the heat stabilizer, etc. ) And may be separately supplied to the melting mixer. Further, these raw material components may be premixed using a mortar, a Henschel mixer, a ball mill, a ribbon blender, or the like, and then supplied to a melting mixer. Further, the pellet prepared by melting and mixing the liquid crystal polyester and the fibrous filler and the pellet prepared by melting and mixing the liquid crystal polyester and the hollow filler are mixed at a desired blending ratio. May be good.

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

The injection molding in the present embodiment is performed by melting the 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 higher and [Tp + 50] ° C. or lower, starting from the flow start temperature Tp ° C. of the liquid crystal polyester composition used.

The temperature of the mold is preferably selected from the range of room temperature (for example, 23 ° C.) to 180 ° C. from the viewpoint of the cooling rate and productivity of the liquid crystal polyester composition.

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

Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited to the present embodiment. The physical characteristics of the liquid crystal polyester were measured by the following method. In the following, Example 3 will be referred to as Reference Example 3.

<Measurement of flow start temperature of liquid crystal polyester>
Using a flow tester (manufactured by Shimadzu Corporation, CFT-500 type), about 2 g of liquid crystal polyester was filled into a cylinder equipped with a die having a nozzle with an inner diameter of 1 mm and a length of 10 mm, and 9.8 MPa (100 kg / cm ²⁾ was filled. ), The liquid crystal polyester was melted and extruded from a nozzle while raising the temperature at a rate of 4 ° C./min, and the temperature showing a viscosity of 4800 Pa · s (48,000 poise) was measured.

<Manufacturing example (manufacturing of liquid crystal polyester)>
A liquid crystal polyester was produced using the following method.

First, 994.5 g (7.2 mol) of parahydroxybenzoic acid, which 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, structural unit C ₁ 446.9 g (2.4 mol) of 4,4'-dihydroxybiphenyl, 299.0 g (1.8 mol) of terephthalic acid giving structural unit B _1, and 99.7 g (0 mol) of isophthalic acid giving structural unit B _2. .6 mol) and 1347.6 g (13.2 mol) of anhydrous acetic acid were charged. 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 to maintain this temperature. The mixture was refluxed for 30 minutes. Further, after adding 2.4 g of 1-methylimidazole, the temperature was raised from 150 ° C. to 320 ° C. over 2 hours and 50 minutes while distilling off distillate by-product acetic acid and unreacted acetic anhydride. After that, the time when the increase in torque was observed 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. The solid content after pulverization is heated in a nitrogen atmosphere from room temperature to 250 ° C. over 1 hour, further heated from 250 ° C. to 295 ° C. over 5 hours, and held at 295 ° C. for 3 hours. , Solid phase polymerization was carried out.

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

<Examples 1 to 3 and Comparative Examples 1 to 2 (blending 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 3 CPU sockets of Comparative Examples 1 and 2 were produced as follows.

Liquid crystal polyester and various fillers are mixed with the mass composition ratio shown in Table 1, and granulation is performed at a cylinder temperature of 340 ° C. using a twin-screw extruder (manufactured by Ikekai Iron Works Co., Ltd., "PCM-30"). By doing so, pelletized liquid crystal polyester compositions (Examples 1 to 3 and Comparative Examples 1 to 4) were obtained.
Then, the obtained pellet-shaped liquid crystal polyester composition was molded under the following molding conditions to support 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 produced. The various fillers used in this example are as follows. The number average fiber length, number average fiber diameter, and number average particle size of various fillers are catalog values.

[Filler]
(1) Hollow filler Glass balloon: S60HS (manufactured by Sumitomo 3M Ltd.), number average particle size 20 μm
(2) Fiber filler Mild 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 size 20 μm

[Molding condition]
Molding machine: "ROBOSHOT S-2000i 30B" manufactured by FANUC
Cylinder temperature: 360 ° C
Mold temperature: 100 ° C
Injection speed: 250 mm / 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 placed on a glass plane, and the height from the glass plane was determined for any 92 points in the CPU socket using a flatness measuring module "9030c" manufactured by Cores Co., Ltd. Then, using the height of the 92 points, the least squares plane of the CPU socket was calculated by the least squares method. The distance from the least squares 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. Calculated as the amount of warpage.

Next, the CPU socket is heated from room temperature to 160 ° C. at a heating rate of 2 ° C./sec, held at 160 ° C. for 1 minute, and further heated to 250 ° C. at a heating rate of 2 ° C./sec to 250. A heat treatment was carried out in which the mixture was held at ° C. for 1 minute and then slowly cooled to 50 ° C.

Then, after cooling the CPU socket after this heat treatment to room temperature, the amount of warpage was measured in the same manner as described above. The above operation was performed on three different test pieces (CPU sockets) produced in Examples and Comparative Examples, respectively, and the average value thereof was defined as the "warp amount after 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 taken as the number of cracks. Table 1 shows the number of cracks generated in the CPU sockets of Examples and Comparative Examples.

(3) Volume Specific Heat First, the specific heat capacity (unit: J / gK) of the liquid crystal polyester composition used in Examples and Comparative Examples was measured by using the method described in JIS K7123: 2012. Specifically, for a test piece (ASTM4 dumbbell test piece) prepared from the liquid crystal polyester composition used in Examples and Comparative Examples, a differential scanning calorimetry device (manufactured by Shimadzu Corporation, “DSC-50”) was used. The specific heat capacity (J / gK) at 100 ° C. was measured using the product.

Next, regarding the test piece (ASTM No. 4 dumbbell test piece) prepared from the liquid crystal polyester composition used in Examples and Comparative Examples, the density (“ASG-320K” manufactured by Kanto Major Co., Ltd.) was used. g / cm ³ ) was measured. The volume specific heat was calculated from the following equation using the measured specific heat capacity and density. 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) x 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 and 2 molded into pellets by a twin-screw extruder were collected in a 2 g crucible. This was treated in an electric furnace at 600 ° C. for 4 hours to incinerate to obtain a residue. This 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.). As filter conditions (analysis conditions), those having an aspect ratio of less than 2, circumscribing rectangular minor diameter (fiber diameter) of less than 5 μm and more than 20 μm, and thinned pixels (fiber length) of less than 20 μm are not fibrous fillers. Excluded all.

As shown in Table 1, in Example 1, 33.3 parts by mass of the fibrous filler having a measured value of the number average fiber length of 70 μm and 33.3 parts by mass of the hollow filler with respect to 100 parts by mass of the resin component (liquid crystal polyester). 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 and 33.3 parts by mass of a granular filler whose actual measurement value of the number average fiber length is less than 190 μm with respect to 100 parts by mass of the liquid crystal polyester. A polyester composition was used. The CPU socket of Comparative Example 2 had a larger amount of warpage after heating and a larger number of cracks than the CPU socket of Example 1. It is considered that this is because 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.

Further, in Comparative Example 1, a liquid crystal polyester composition containing 66.7 parts by mass of a fibrous filler having a measured value of number average fiber length of less than 190 μm was used with respect to 100 parts by mass of the liquid crystal polyester. From the results of Example 1 and Comparative Example 1, it was shown that the amount of warpage of the CPU socket after heating and the number of cracks generated can be reduced by adding the hollow filler.

As described above, according to the present embodiment, it was shown that it is possible to provide a connector having a small amount of warpage while suppressing the occurrence of cracks.

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

Claims (5)

A hollow filler, the number average fiber length and a fibrous filler is less than 20μm more than 80 [mu] m seen including,
The hollow filler has a number average particle size of 5 μm or more and 100 μm or less.
The amount of the hollow filler added is more than 30 parts by mass and 80 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.
The amount of the fibrous filler added is 5 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.
A liquid crystal polyester composition in which the liquid crystal polyester contains the following structural units in an amount of 30 mol% or more based on all the repeating units of the liquid crystal polyester.

The liquid crystal 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. Volume specific heat at 100 ° C. is a liquid crystal polyester composition according to claim 1 or 2 or less 1.0 J / cm ³ K or more 3.0J / cm ³ K. A resin molded product formed of the liquid crystal polyester composition according to any one of claims 1 to 3 . The resin molded product according to claim 4 , which is a connector.

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