Patent Description:
In the recent years, along with the increase of amount of information and communications in the field of telecommunications, the use is increased of signals having frequency of high frequency band in electronic and communication devices, and especially signals are widely used having frequency of gigahertz (GHz) band which the frequency is <NUM><NUM> or more. For example, in the automobile field, high frequency band of GHz band is used. In particular, for millimeter wave radars and quasi-millimeter wave radars loaded for the purpose of crash prevention of the automobiles, there are used high frequency of <NUM> to <NUM> and <NUM>, respectively, and those use are expected to grow further in the future.

However, the higher the frequency of the signal used, the lower becomes the quality of the emission signals which may cause erroneous recognition of information, i.e., the transmission loss becomes larger. This transmission loss consists of conductor loss due to a conductor and dielectric loss due to a resin for insulation which constitutes the electric and electronic components such as substrates in the electronic and communication devices, and since the conductor loss is proportional to <NUM> power of the frequency used and the dielectric loss to <NUM> power of the frequency, the effect due to this dielectric loss becomes extremely large in the high frequency band, particularly in the GHz band. In addition, since the dielectric loss also increases in proportion to the dielectric tangent of the resin, a resin having a low dielectric tangent is required for preventing degradation of information.

In relation to the above-described problem, Patent Document <NUM> proposes a liquid crystalline aromatic polyester comprising <NUM> or more of a structural unit derived from p- or m-hydroxybenzoic acid and a structural unit derived from hydroxynaphthoic acid as a liquid crystalline aromatic polyester which shows low dielectric tangent in the high frequency band.

The resin which constitutes the electric and electronic components is required to have a high heat resistance to the heat which occurs at the time of molding (film forming stability), and a molded article such as a film by use thereof is required to have a high heat resistance to the heating process in which soldering or the like is used. In relation to such problem, Patent Document <NUM> proposes a polyester resin comprising <NUM> to <NUM> % of a structural unit derived from p-hydroxybenzoic acid, <NUM> to <NUM> % of a structural unit derived from <NUM>-hydroxy-<NUM>-naphthoic acid, <NUM> to <NUM> % of a structural unit derived from an aromatic diol compound, and <NUM> to <NUM> % of a structural unit derived from aromatic dicarboxylic acid as a wholly aromatic polyester, excellent in heat resistance and the like.

The wholly aromatic liquid crystalline polyester resin is also widely used in surface mounting electronic components obtainable from injection molding, since it is excellent in heat resistance and thin-wall formability. Since it is also a material having small dielectric loss and excellent electric properties, recently, methods to mold the aromatic liquid crystalline polyester into a film form are reviewed by T-die extrusion process or inflation process, solution cast process and the like.

In relation to the above-described problem, Patent Document <NUM> proposes an aromatic liquid crystalline polyester consisting of <NUM> - <NUM> mol % of repeating structural unit (I) derived from <NUM>-hydroxy-<NUM>-naphthoic acid, <NUM> - <NUM> mol % of repeating structural unit (II) derived from an aromatic diol compound, <NUM> - <NUM> mol % of repeating structural unit (III) derived from <NUM>,<NUM>-naphthalene dicarboxylic acid, <NUM> - <NUM> mol % of repeating structural unit (IV) derived from terephthalic acid or <NUM>,<NUM>'-biphenyl dicarboxylic acid, which the molar ratio of repeating structural units (III) and (IV) satisfy the relationship of : (III) / {(III) + (IV)} ≥ <NUM>, as an aromatic liquid crystalline polyester having excellent balance between the heat resistance and film processability and a small conductor loss.

Patent Document <CIT> discloses wholly aromatic liquid crystalline polyester resins comprising structural units derived from <NUM> mol% of <NUM>-hydroxy-<NUM>-naphtoic acid (HNA), <NUM> mol% of <NUM>,<NUM>'-dihydroxy biphenyl (BP), <NUM> mol% of terephtalic acid (TA), <NUM> mol% of <NUM>,<NUM>-naphtalene dicarboxylic acid (NDA) and <NUM> mol% of isophtalic acid (IA).

In the recent years, the amount of information and communication is continuously rapidly growing, the frequency of the signals used is even higher, and a resin is required which has a further low dielectric tangent in the high frequency band. The present inventors have found that even the use of the polyester resin proposed in Patent Document <NUM> will not show a sufficiently low dielectric tangent that is required in the high frequency band. Likewise, the present inventors have found that even the use of the polyester resin proposed in Patent Document <NUM> will not show the low dielectric tangent that is required in the high frequency band.

In order to solve the above-described technical problems, the present inventors intensively studied to find that a wholly aromatic liquid crystalline polyester resin having a low dielectric tangent and a high heat resistance is obtainable by adjusting the specific structural unit and the specific composition ratio in a wholly aromatic liquid crystalline polyester resin.

Also, the present inventors have found that even by the use of the polyester resin as proposed in Patent Document <NUM> will not attain sufficient processability into a film or a fiber. In particular, it was found that the melt elongation property is not enough, which guarantees the processability and elongation processability when the resin is melted.

In the recent years, the amount of information communication is continuously rapidly growing, the frequency of the signals used is even higher, and a resin is required having an even lower dielectric tangent in the gigahertz (GHz) band which the frequency is <NUM><NUM> or more. Furthermore, when designing a device or the like by using such resin, a sufficient heat resistance is necessary since in general, heat process of high heat is carried out such as process by soldering. The present inventors have found out that the polyester resin as proposed in Patent Document <NUM> cannot satisfy both of the sufficiently low dielectric tangent required in the high frequency band of <NUM> measurement frequency and the sufficient heat resistance.

In order to solve the above-described technical problems, the present inventors intensively studied to find that a wholly aromatic liquid crystalline polyester resin having an excellent balance between the heat resistance and processability while having an especially low dielectric tangent is obtainable by adjusting the specific structural unit and the specific composition ratio in a wholly aromatic liquid crystalline polyester resin.

The objective of the present invention is to provide a wholly aromatic liquid crystalline polyester resin having an excellent heat resistance while having a notably low dielectric tangent.

The objective of the present invention is also to provide a wholly aromatic liquid crystalline polyester resin having excellent balance of the heat resistance and processability while having a notably low dielectric tangent.

Further the objective of the present invention is to provide a molded article comprising said wholly aromatic liquid crystalline polyester resin and electric and electronic components comprising molded article.

The wholly aromatic liquid crystalline polyester resin according to the present disclosure comprises,.

A first object of the present invention is a wholly aromatic liquid crystalline polyester resin as described in claim <NUM>, comprising,.

In the present invention, preferably the composition ratio (mol %) of the structural units further satisfies the following conditions: <MAT> <MAT> <MAT> <MAT>.

In the present invention, preferably structural unit (II) is represented by the following formula:
<CHM>
wherein Ar<NUM> is selected from the group consisting of phenyl, biphenyl, naphtyl, anthryl, and phenanthryl, optionally having a substituent group.

In the present disclosure, the molar ratio of structural unit (III A) to the total of structural units (III B) and (III C) (structural unit (III A) / (structural unit (III B) + (III C)) is preferably from <NUM> to <NUM>.

In the present invention, the melting point measured as described in the present disclosure is preferably <NUM> or more.

In the present invention, the dielectric tangent in measurement frequency <NUM> as measured according to the present disclosure is <NUM> × <NUM>-<NUM> or less.

In another aspect of the present invention, the elongation ratio of a melt strand extruded under the conditions of melting point of the liquid crystalline polyester resin +<NUM> and shear rate of <NUM>-<NUM> is preferably <NUM> times or more.

In another aspect of the present invention, the dielectric tangent in measurement frequency <NUM> as measured according to the present disclosure is preferably less than <NUM> × <NUM>-<NUM>.

In another aspect of the present invention, preferably the dielectric tangents of <NUM> and <NUM> in measurement frequency of <NUM> as measured according to the present disclosure are less than <NUM> × <NUM>-<NUM> and less than <NUM> × <NUM>-<NUM> respectively.

In another aspect of the present invention, the rate of change of dielectric tangent from <NUM> to <NUM> in measurement frequency <NUM> is preferably less than <NUM> × <NUM>-<NUM>/ °C.

In another aspect of the present invention, the melt viscosity measured in accordance with the present disclosure at a temperature of melting point of the liquid crystalline polyester resin +<NUM> and shear rate of <NUM>-<NUM> is preferably from <NUM> to <NUM> Pa·s.

The molded article according to the present invention is characterized in comprising the above-described wholly aromatic liquid crystalline polyester resin.

In the present invention, the molded article is preferably in a film form.

In the present invention, the molded article is preferably in a fibre form.

In the present invention, the molded article is preferably an injection molded article.

The electric and electronic components according to the present invention are characterized in comprising the above-described molded article.

According to the present invention, it is possible to attain a wholly aromatic liquid crystalline polyester resin having a notably low dielectric tangent and a high melting point by selecting the unit which constitutes the wholly aromatic liquid crystalline polyester resin into a specific structural unit and a specific composition ratio thereof.

Therefore, it is possible to prevent the quality degradation of the emission signals in electric and electronic devices or telecommunication devices which use signals of high frequency when they are processed and molded and used as a product.

The wholly aromatic polyester resin of the present invention also has high film forming stability, and the molded article made by use thereof have high stability against heat processing in which soldering or the like is used.

According to another aspect ofthe present invention, it is possible to attain a wholly aromatic liquid crystalline polyester resin having a notably low dielectric tangent, and excellent balance of the heat resistance and processability by selecting the unit which constitutes the wholly aromatic liquid crystalline polyester resin into a specific structural unit and a specific composition ratio thereof. Therefore, it is possible to prevent the quality degradation of the emission signals in electric and electronic devices or telecommunication devices which use signals of high frequency when they are processed and molded and used as a product. The wholly aromatic polyester resin of the present invention is suitable for injection molding and also has high spinnability and film forming stability, and the molded article made by use thereof have high stability against heat processing in which soldering or the like is used.

The wholly aromatic liquid crystalline polyester resin according to the present disclosure comprises structural unit (I) derived from <NUM>-hydroxy-<NUM>-naphthoic acid, structural unit (II) derived from an aromatic diol compound, and structural unit (III) derived from an aromatic dicarboxylic compound, wherein structural unit (III) comprises structural unit (III A) derived from terephthalic acid, and at least one of structural unit (III B) derived from <NUM>,<NUM>-naphthalene dicarboxylic acid and structural unit (III C) derived from isophthalic acid and satisfies a specific composition ratio. The lower limit of the total structural units from (I) to (III) is preferably <NUM> mol % or more, more preferably <NUM> mol % or more as the lower limit and further preferably <NUM> mol % or more, and the upper limit is preferably <NUM> mol % or less, based on the structural units of the entire wholly aromatic liquid crystalline polyester resin.

According to the wholly aromatic liquid crystalline polyester resin having such constitution, it is possible to attain a wholly aromatic liquid crystalline polyester resin having a notably low dielectric tangent. Further since the wholly aromatic liquid crystalline polyester resin can have a high melting point, it is possible to enhance the heat resistance against heat processing of the molded article made by the use thereof, along with enhancement of film forming stability.

Since it is also possible to attain a wholly aromatic polyester resin with a high glass transition temperature, the heat resistance in actual use of the molded article by use thereof can be improved, thus use can be made under an environment of higher temperatures.

Moreover, it is possible to lower the volume expansion coefficient, so a wholly aromatic liquid crystalline polyester resin can be attained having high dimension stability at the time of molding and processing.

In the present invention, the dielectric tangent (measurement frequency: <NUM>) of the wholly aromatic liquid crystalline polyester resin is <NUM> × <NUM>-<NUM> or less, more preferably <NUM> × <NUM>-<NUM> or less, and further preferably <NUM> × <NUM>-<NUM> or less.

In the present specification, the dielectric tangent of the wholly aromatic liquid crystalline polyester resin can be measured by split post dielectric resonator method (SPDR method) by means of Network Analyzer N5247A from Keysight Technoligies.

In the present invention, the lower limit of the melting point of the wholly aromatic liquid crystalline polyester resin is preferably <NUM> or more, more preferably <NUM> or more, further preferably <NUM> or more, and the upper limit is preferably <NUM> or less, more preferably <NUM> or less. By selecting the melting point of the wholly aromatic liquid crystalline polyester resin according to the present invention within the above-described numerical range, it is possible to enhance the heat resistance against heat processing of the molded article made by the use thereof, along with enhancement of film forming stability.

In another aspect of the present invention, the lower limit of the melting point of the wholly aromatic liquid crystalline polyester resin is preferably <NUM> or more, more preferably <NUM> or more, further preferably <NUM> or more, and the upper limit is preferably <NUM> or less, more preferably <NUM> or less, further preferably <NUM> or less. By selecting the melting point of the wholly aromatic liquid crystalline polyester resin according to the present invention within the above-described numerical range, it is possible to enhance the heat resistance against heat processing of the molded article made by the use thereof, along with enhancement of film forming stability and spinnability stability.

In the present specification, the melting point of the wholly aromatic liquid crystalline polyester resin is in accordance with ISO11357, ASTM D3418 test method and can be measured by using a differential scanning calorimeter (DSC) manufactured by Hitachi High-Tech Science Corporation or the like.

In the present invention, the glass transition temperature of the wholly aromatic liquid crystalline polyester resin is preferably <NUM> or more and more preferably <NUM> or more.

By selecting the glass transition temperature of the wholly aromatic liquid crystalline polyester resin of the present invention within the above-described numerical range, the heat resistance of the molded article can be enhanced which is made by use of the wholly aromatic polyester resin according to the present invention and used in electronic devices and telecommunications devices or the like, therefore, use under a higher temperatured environment can be attained.

In the present specification, the glass transition temperature of the wholly aromatic liquid crystalline polyester resin is inaccordance with JISK7244 and can be obtained from a peak top temperature of tan D obtainable from dynamic viscoelasticity measurement by use of a dynamic viscoelasticity measuring device (manufactured by Hitachi High-Tech Science Corporation, product name: DMA7100) or the like).

In the present invention, the volume expansion coefficient of the wholly aromatic liquid crystalline polyester resin is preferably <NUM> ppm/ °C or less, more preferably <NUM> ppm/ °C or less, and more preferably <NUM> ppm/ °C or less, in view of the dimension stability at the time of molding.

In the present specification, the volume expansion coefficient of the wholly aromatic liquid crystalline polyester resin can be measured using a thermomechanical analyzing device (manufactured by Hitachi High-Tech Science Corporation, product name: TMA7000) from a molded article obtained from heat melting and injection molding or press molding, film molding the resin.

In the present invention, the lower limit of the melt viscosity of the liquid crystalline polyester resin at the melting point of the liquid crystalline polyester resin + <NUM> and shear rate of <NUM>-<NUM> is preferably <NUM> Pa·s or more and more preferably <NUM> Pa·s, and the upper limit is preferably <NUM> Pa·s or less and more preferably <NUM> Pa·s or less, in view of formability.

In another aspect of the present invention, the lower limit of the melt viscosity of the liquid crystalline polyester resin at the melting point of the liquid crystalline polyester resin + <NUM> and shear rate of <NUM>-<NUM> is preferably <NUM> Pa·s or more and more preferably <NUM> Pa·s or more, and the upper limit is preferably <NUM> Pa-s or less and more preferably <NUM> Pa-s or less, in view of formability.

In the present specification, the viscosity of the wholly aromatic liquid crystalline polyester resin can be measured using a capillary rheometer viscometer, in accordance with JIS K7199.

The wholly aromatic liquid crystalline polyester resin of the second aspect of the present invention can provide a stable processability into a fiber or a film as it has a sufficient melt elongation property. Also, a wholly aromatic liquid crystalline polyester resin having a notably low dielectric tangent can be obtained. Further, since it is possible to obtain a wholly aromatic liquid crystalline polyester resin having a high melting point, the molded article made by use thereof can attain high heat stability to heat processing.

In another aspect of the present invention, since a wholly aromatic polyester resin having a high glass transition temperature can be obtained, the heat resistance in actual use of the molded article made by the use thereof can be enhanced, and use under a higher temperature environment can be attained. Further, the volume expansion coefficient can be reduced so that a wholly aromatic liquid crystalline polyester resin can be attained having a high dimension stability at the time of molding and processing.

In another aspect of the present invention, the melt elongation property of the liquid crystalline polyester resin can be evaluated by measuring the elongation ratio of the melt strand. With respect to the melt elongation property of the liquid crystalline polyester resin according to the present invention, the elongation ratio (= withdrawing rate at the end of measurement (m/min) / extrusion rate converted at capillary passing (m/min)) of the melt strand when the melt strand which was extruded under the conditions of the melting point of the liquid crystalline polyester resin + <NUM> and shear rate of <NUM>-<NUM> was withdrawn while accelerating the withdrawing rate by a winding roller via a pulley is preferably <NUM> times or more, and more preferably <NUM> times or more, in view of processability into a fiber or a film. In the present specification, the melt elongation property of the wholly aromatic liquid crystalline polyester resin can be meausered by using CAPILOGRAPH 1D manufactured by Toyo Seiki Seisaku-sho.

The tensile force (= melt tensile force) of the melt strand at the end point of the above-described measurement is <NUM> mN or more, and preferably <NUM> mN or more, in view of processability into a fiber or a film.

In another aspect of the present invention, the dielectric tangent (measurement frequency: <NUM>) of the wholly aromatic liquid crystalline polyester resin is preferably <NUM> × <NUM>-<NUM> or less, more preferably <NUM> × <NUM>-<NUM> or less, and further preferably <NUM> × <NUM>-<NUM> or less.

The dielectric tangent (measurement frequency: <NUM>) of the wholly aromatic liquid crystalline polyester resin is preferably less than <NUM> × <NUM>-<NUM>, more preferably less than <NUM> × <NUM>-<NUM>, and further preferably less than <NUM> × <NUM>-<NUM>.

The dielectric tangents (measurement frequency: <NUM>) at <NUM> and <NUM> of the wholly aromatic liquid crystalline polyester resin are preferably less than <NUM> × <NUM>-<NUM> and less than <NUM> × <NUM>-<NUM>, more preferably less than <NUM> × <NUM>-<NUM> and less than <NUM> × <NUM>-<NUM>, and further preferably less than <NUM> × <NUM>-<NUM> and less than <NUM> × <NUM>-<NUM>, respectively.

The rate of change of the dielectric tangent from <NUM> to <NUM> in measurement frequency <NUM> is preferably less than <NUM> × <NUM>-<NUM>/ °C, more preferably less than <NUM> × <NUM>-<NUM>/ °C, and further preferably less than <NUM> × <NUM>-<NUM>/ °C.

In the present specification, the dielectric tangent in <NUM> of the wholly aromatic liquid crystalline polyester resin can be measured by the split post dielectric resonator method (SPDR method) by using network analyzer N5247A from Keysight Technoligies or the like. Other dielectric tangent can be measured by cylindrical cavity resonator method. Unless particularly specified, the value of the dielectric tangent is the measured value at <NUM>, under ambient atmosphere, at humidity of <NUM> %.

The liquid crystallinity of the wholly aromatic liquid crystalline polyester resinofthe present invention can be confirmed by observing the presence/absence of optical anisotropy after heat melting the wholly aromatic liquid crystalline polyester resin on the microscope heating stage by using a polarizing microscope manufactured by Olympus Corporation (product name: BH-<NUM>) with a microscope heating stage manufactured by Mettler (product name: FP82HT).

Each structural unit comprised in the wholly aromatic liquid crystalline polyester resin is explained below.

The wholly aromatic liquid crystalline polyester resin comprises structural unit (I) derived from <NUM>-hydroxy-<NUM>-naphthoic acid which is expressed by formula (I) described below, and the composition ratio (mol %) of structural unit (I) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more and <NUM> mol % or less.

Monomer which gives structural unit (I) include <NUM>-hydroxy-<NUM>-naphthoic acid(HNA, formula (<NUM>) as described below), acetylated product, ester derivative, acid halide thereof, or the like.

In the present disclosure, the lower limit of the composition ratio (mol %) of structural unit (I) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, preferably <NUM> mol % or more, more preferably <NUM> mol % or more, further more preferably <NUM> mol % or more, and most preferably <NUM> mol % or more, and the upper limit is <NUM> mol % or less, preferably <NUM> mol % or less, more preferably <NUM> mol % or less, further more preferably <NUM> mol % or less, most preferably <NUM> mol % or less, in view of reducing the dielectric tangent and improving the melting point of the wholly aromatic liquid crystalline polyester resin.

In the present invention, the lower limit of the composition ratio (mol %) of structural unit (I) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, more preferably <NUM> mol % or more, and further preferably <NUM> mol % or more, and the upper limit is <NUM> mol % or less, preferably <NUM> mol % or less, more preferably <NUM> mol % or less, and further preferably <NUM> mol % or less, in view of reducing the dielectric tangent and elevating the melting point of the wholly aromatic liquid crystalline polyester resin.

The wholly aromatic liquid crystalline polyester resin comprises structural unit (II) derived from an aromatic diol compound, and the composition ratio (mol %) of structural unit (II) in the liquid crystalline polyester is <NUM> mol % or more and <NUM> mol % or less. The wholly aromatic liquid crystalline polyester resin may comprise two or more of structural units (II).

In one embodiment, structural unit (II) is represented by the following formula
<CHM>.

Ar<NUM> in the above-described formula is selected from the group consisting of phenyl, biphenyl, naphtyl, anthryl, and phenanthryl, optionally having a substituent group. Amongst these, phenyl and biphenyl are more preferable. The substituent group includes hydrogen, an alkyl group, an alkoxy group, and fluorine or the like. Number of carbons which the alkyl group has is preferably from <NUM> to <NUM> and more preferably from <NUM> to <NUM>. The alkyl group may be straight chained or branched. Preferably, the alkoxy group has <NUM> to <NUM> carbons and more preferably <NUM> to <NUM> carbons.

Monomer which gives structural unit (II) are for example, hydroquinone (HQ, formula(<NUM>) as below), <NUM>,<NUM>-dihydroxybiphenyl (BP, formula (<NUM>) as below), <NUM>,<NUM>'-dimethyl-<NUM>,<NUM>'-biphenyl-<NUM>,<NUM>'-diol (OCBP, formula (<NUM>) as below) and the acylated products thereof or the like. <CHM>
<CHM>
<CHM>.

In the present disclosure, the lower limit of the composition ratio (mol %) of structural unit (II) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, preferably <NUM> mol % or more, more preferably <NUM> mol % or more, further preferably <NUM> mol % or more, especially preferably <NUM> mol % or more, and most preferably <NUM> mol % or more, and the upper limit is <NUM> mol % or less, preferably <NUM> mol % or less, more preferably <NUM> mol % or less, further more preferably <NUM> mol % or less, most preferably <NUM> mol % or less, in view of reducing the dielectric tangent and elevating the melting point of the wholly aromatic liquid crystalline polyester resin.

In the present invention, the lower limit of the composition ratio (mol %) of structural unit (II) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, preferably <NUM> mol % or more, more preferably <NUM> mol % or more, further preferably <NUM> mol % or more, and the upper limit is preferably <NUM> mol % or less, more preferably <NUM> mol % or less, further preferably <NUM> mol % or less, in view of reducing the dielectric tangent and elevating the melting point of the wholly aromatic liquid crystalline polyester resin.

Structural unit (III) derived from an aromatic dicarboxylic compound in the wholly aromatic liquid crystalline polyester resin comprises structural unit (III A) derived from terephthalic acid represented by formula (III A) as below, and at least one of structural unit (III B) derived from <NUM>,<NUM>-naphthalene dicarboxylic acid and structural unit (III C) derived from isophthalic acid.

The composition ratio (mol %) of structural unit (III) in the liquid crystalline polyester for example satisfies the following condition: <MAT> and the composition ratio of structural unit (III) is preferably substantially in equivalent amount to the composition ratio of structural unit (II) (structural unit (III) ≒ structural unit (II)).

The composition ratio (mol %) of structural unit (III) in the liquid crystalline polyester satisfies the following conditions: <MAT> <MAT> <MAT> (provided that both of structural unit (III B) and structural unit (III C) is not <NUM> mol %). <CHM>
<CHM>
<CHM>.

Monomers which give structural unit (III A) are terephthalic acid (TPA, formula (<NUM>) as below), ester derivatives thereof, acid halide, or the like. TPA and other derivatives are used widely as a raw material for general plastics such as polyethylene terephthalate, and since they are of the lowest cost class amongst the aromatic dicarboxylic compound, cost superiority of the resin products can be enhanced by increasing the composition ratio of structural unit (III A) in structural unit (III). Therefore, in view of costs, the composition ratio (mol %) of structural unit (III) preferably satisfies: structural unit (III A) > (structural unit (III B) + structural unit (III C)). By increasing the composition ratio of structural unit (III A) in structural unit (III), improvement in the heat resistance can also be expected.

Monomers which give structural unit (III B) are <NUM>,<NUM>-naphthalene dicarboxylic acid (NADA, formula (<NUM>) as below), and ester derivatives thereof, acid halide, or the like. Since the cost of NADA is higher than TPA, cost superiority of the resin products can be enhanced by decreasing the composition ratio of structural unit (III B) in structural unit (III).

Monomers which give structural unit (III C) are isophthalic acid (IPA, formula (<NUM>) as below) and ester derivatives thereof, acid halide, or the like.

In the present disclosure, the lower limit of the composition ratio (mol %) of structural unit (IIIA) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol %, preferably <NUM> mol % or more, more preferably <NUM> mol % or more, further preferably <NUM> mol % or more, further preferably <NUM> mol % or more, especially preferably <NUM> mol % or more, and most preferably <NUM> mol % or more, and the upper limit is less than <NUM> mol %, preferably <NUM> mol % or less, more preferably <NUM> mol % or less, further more preferably <NUM> mol % or less, and most preferably <NUM> mol % or less, in view of reducing the dielectric tangent and elevating the melting point of the wholly aromatic liquid crystalline polyester resin.

The lower limit of the composition ratio (mol %) of structural unit (III B) in the wholly aromatic liquid crystalline polyester resin is more than <NUM> mol %, and the upper limit is less than <NUM> mol % and preferably <NUM> mol % or less.

The lower limit of the composition ratio (mol %) of structural unit (III C) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, preferably more than <NUM> mol %, more preferably <NUM> mol % or more, and the upper limit is less than <NUM> mol % and preferably <NUM> mol % or less.

The lower limit of the composition ratio (mol %) of the total of structural unit (III B) and structural unit (III C) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, and the upper limit is less than <NUM> mol % and preferably <NUM> mol % or less.

In the wholly aromatic polyester resin, preferably the molar ratio of structural unit (III A) to the total of structural unit (III B) and (III C) (structural unit (III A)/(structural unit (III B) + (III C)) is <NUM> or more, more preferably <NUM> or more, and further preferably <NUM> or more. Also, such molar ratio is preferably <NUM> or less, more preferably <NUM> or less, further preferably <NUM> or less, further more preferably <NUM> or less. By selecting the molar ratio of structural unit (III A) to the total of structural unit (III B) and (III C) within the the above-described numerical range, the volume expansion coefficient can be reduced and also the melting point can be elevated of the wholly aromatic polyester resin.

In the present invention, the lower limit of the composition ratio (mol %) of structural unit (IIIA) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol %, preferably <NUM> mol % or more, more preferably <NUM> mol % or more, further preferably <NUM> mol % or more, and the upper limit is <NUM> mol % or less, preferably <NUM> mol % or less, more preferably <NUM> mol % or less, and further preferably <NUM> mol % or less, in view of reducing the dielectric tangent and elevating the melting point of the wholly aromatic liquid crystalline polyester resin.

The lower limit of the composition ratio (mol %) of structural unit (IIIB) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, preferably <NUM> mol % or more, more preferably <NUM> mol % or more, and further preferably <NUM> mol % or more and the upper limit is <NUM> mol % or less.

The lower limit of the composition ratio (mol %) of structural unit (IIIC) in the wholly aromatic liquid crystalline polyester resin is <NUM> mol % or more, preferably more than <NUM> mol % and more preferably <NUM> mol % or more, the upper limit is less than <NUM> mol % and preferably <NUM> mol % or less.

In the wholly aromatic polyester resin, preferably the lower limit of the molar ratio of structural unit (III A) to structural unit (III B) (structural unit (III A) / structural unit (III B)) is preferably <NUM> or more, more preferably <NUM> or more, further preferably <NUM> or more, and further more preferably <NUM> or more, and the upper limit is preferably <NUM> or less, more preferably <NUM> or less, and further preferably <NUM> or less.

The wholly aromatic liquid crystalline polyester resin according to the present invention can be prepared by polymerization of monomers giving structural units (I) to (IV), using conventional known methods such as melt polymerization, solid state polymerization, solution polymerization, and slurry polymerization.

In one embodiment, the wholly aromatic liquid crystalline polyester resin according to the present invention can be prepared by melt polymerization only. Preparation is also possible by a two-stage polymerization, in which melt polymerization is carried out to give a prepolymer which is further subjected to solid state polymerization.

In view of obtaining the polyester compound according to the present invention in an efficient manner, the melt polymerization is preferably carried out by combining the monomers giving the above-described structural units (I) to (IV) in a given blend to <NUM> mol %, in the presence of <NUM> to <NUM> mol equivalent of acetic anhydride based on the total hydroxyl groups which the monomers have and under acetic acid reflux.

When polymerization reaction is performed by the two-stage of melt polymerization followed by solid state polymerization, preference is made to select the method in which, for example, the prepolymer obtained by melt polymerization is cooled and solidified, subsequently triturated into a powder form or flake form, and then by a known solid state polymerization method, for example under an inert atmosphere such as nitrogen or vacuum, at a temperature range from <NUM> to <NUM>, the prepolymer resin is heat processed for <NUM> to <NUM> hours. The solidstate polymerization may be carried out while stirring or in a static state without stirring.

In the polymerization reaction, a catalyst may be or may not be used. The catalyst used can be those conventionally known as the catalyst for polymerization of polyester, including metal salt catalysts such as magnesium acetate, tin (I) acetate, tetrabutyl titanate, lead acetate, sodium acetate, potassium acetate, antimony trioxide, and organic compound catalysts such as nitrogen containing heterocyclic compounds such as N-methyl imidazole. The amount of catalysts used is preferably, without particular limitation, <NUM> to <NUM> parts by weight based on the total amount of <NUM> parts by weight of the monomers.

The polymerization reactor used in the melt polymerization is preferably, withoutparticular limitation, a reactor used for reaction of a general highly viscous fluid. Examples of these reactors include, for example, anchor type, multi-stage type, spiral band type, spiral shaft type, or the like, or variations thereof which are stirring stirring tank type polymerization reactors having stirring units with stirring blades of various shapes, or mixing devices which are generally used for kneading resins such as a kneader, a roll mill, a bunbury mixer, or the like.

The molded article according to the present invention is those comprising the wholly aromatic liquid crystalline polyester resin, and the shape thereof is appropriately changed in accordance with the purposes, examples being, without particular limitation, a film form, a plate form, a fiber form, or the like.

The molded article according to the present invention may comprise other resinthanthe wholly aromatic liquid crystalline polyester resin, as long as the effect of the present invention is not compromised. Examples include, polyester resins such as polyethylene terephthalate, polyethylene naphtalate, polyarylate, and polybutyrene terephthalate, polyolefin resin such as polyethylene and polypropylene, vinyl resins such as cycloolefin polymer and polyvinylchloride, (meth) acryl resins such as polyacrylate, polymethacrylate, and polymethyl methacrylate, polyphenylene ether resin, polyacetal resin, polyamide resin, imide resins such as polyimide and polyether imide, polystyreneresins such as polystyrene, high-impact polystyrene, ASresin andABS resin, thermosetting resin such as epoxy resin, cellulose resin, polyether ether ketone resin, fluorine resin and polycarbonate resin, and the molded article may comprise one or two or more of these.

The molded article according to the present invention may comprise other additives, for example, a colorant, a dispersing agent, an antioxidant, a curing agent, a flame retardant, a heat stabilizer, a UV absorber, an antistatic agent, and a surfactant, as long as the effect of the present invention is not compromised.

The molded article according to the present invention can be obtained by subjecting a mixture comprising the wholly aromatic liquid crystalline polyester resin and optionally other resins or additives to press molding, foam molding, injection molding, extrusion molding, and punch molding.

The mixture can be obtained by melt kneading the wholly aromatic liquid crystalline polyester resin, etc., by using a banbury mixer, a kneader, a single or twin screw extruder, or the like.

In one embodiment, the molded article is preferably in a film form. The film can be obtained by a conventionally known method, for example, extrusion molding such as inflation molding and melt extrusion molding, and melt casting method. The film thus obtained may be a single layered film consisted of the wholly aromatic liquid crystalline polyester resin, or may be a multi-layered film with different kinds of materials.

The molded films by melt extrusion or solution casting may be subjected to elongation process in a single or twin screw, for the purpose of improving the dimension stability and mechanical property. Thermal process may be carried out for the purpose of removing anisotropy or improving the heat resistance of the film.

In one embodiment, the molded article is preferably in a fiber form. Fibers can be obtained by conventionally known methods such as by melt spinning method, solution spinning method or the like. The fibers can be made of the wholly aromatic liquid crystalline polyester resin only, or mixed with other resins.

The electric and electronic components according to the present inventioncomprise the above-describedwholly aromatic liquid crystalline polyester resin. Examples of the electric and electronic components include ETC, GPS, wireless LAN and antennas used in lectrical and electronic devices such as mobile phones, a high-speed transmission connector, a CPU socket, a circuit board, a flexible printed circuit board (FPC), a circuit board for lamination, a millimeter wave or a quasi-millimeter radar such as a radar for collision prevention, RFID tag, a condenser, an inverter part, an insulation film, a coating material for a cable, an insulation material of battery accumulator such as lithium-ion battery, a vibrating plate of a speaker, or the like.

In one embodiment, the electric and electronic components comprise a molded article (e.g., an injection molded article or a film, etc.) which comprises the wholly aromatic liquid crystalline polyester resin.

In the followings, the present invention will be described in more details by the Examples; however, the present invention shall not be limited to the Examples.

To begin with, the first embodiment of the present invention will be described in details with the aid of the Examples and Comparative Examples.

To a polymerization vessel with a stirring blade, <NUM> (<NUM> mol %) of <NUM>-hydroxy-<NUM>-naphthoic acid (HNA), <NUM> (<NUM> mol %) of <NUM>,<NUM>-dihydroxybiphenyl (BP), <NUM> (<NUM> mol %) of terephthalic acid (TPA), and <NUM> (<NUM> mol %) of isophthalic acid (IPA) were added, and potassium acetate and magnesium acetate were feeded as the catalyst, and after carrying out nitrogen substitution by reducing the pressure of the polymerization vessel and injecting nitrogen for <NUM> times, <NUM> (<NUM> mol equivalent based on a hydroxyl group) of acetic anhydride was further added, the temperature elevated to <NUM>, and acetylation reaction was performed for <NUM> hours in a reflux state.

After acetylation has ended, the polymerization vessel in a state of which acetic acid was distilled out was heated at <NUM> /min, and the polymerization product was taken out when the temperature of the melt product in the vessel reached <NUM>, and cooled to solidify. The obtained polymerization product was triturated into the size which will pass through a sieve having a sieve opening of <NUM> to obtain a prepolymer.

Then, the prepolymer obtained as above was heated from room temperature to <NUM> over <NUM> hours by using a heating machine with an oven manufactured by Yamato Scientific Co. , Ltd, and subsequently, the temperature was kept at <NUM> for <NUM> hours and solid state polymerization was performed. Subsequently, heat was naturally released at room temperature to obtain wholly aromatic liquid crystalline polyester resin A. Wholly aromatic liquid crystalline polyester resin A specimen was heat melted on a microscope heating stage by using a polarization microscope manufactured by Olympus Corporation (product name: BH-<NUM>) with a hot stage for microscopes manufactured by Mettler (product name: FP82HT) to confirm liquid crystallinity by the presence/absence of optical anisotropy.

Liquid crystalline polyester resin B was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP20 mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin C was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin D was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid statepolymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin E was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin F was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and <NUM>,<NUM>-naphthalene dicarboxylic acid (NADA) <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin G was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin H was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin I was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin J was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin K was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin L was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin M was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin N was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin O was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and IPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin P was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to p-hydroxybenzoic acid (HBA) <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, IPA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin Q was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HBA <NUM> mol %, HNA <NUM> mol %, BP <NUM> mol %, and TPA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Liquid crystalline polyester resin R was obtained in a similar manner as Comparative Example <NUM>-<NUM>', except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

The wholly aromatic liquid crystalline polyester resins obtained by the Examples and Comparative Examples were heat melted at the condition of the melting point to melting point + <NUM>, and injection molded to prepare flat plate test specimens of <NUM> × <NUM> × <NUM>. The dielectric tangent of frequency of <NUM> of the in-plane direction of these test specimens were measured by the split post dielectric resonator method (SPDR method) by means of Network Analyzer N5247A from Keysight Technoligies.

The melting point of the wholly aromatic liquid crystalline polyester resins obtained by the Examples and Comparative Examples by a differential scanning calorimeter (DSC) manufactured by Hitachi High-Tech Science Corporation. The temperature was elevated from room temperature to <NUM> - <NUM> at a rate of temperature increase of <NUM>/min to melt the polymer completely, and then the temperature was lowered to <NUM> at a rate of <NUM>/min, and an endotherm peak obtained when further elevating the temperature to <NUM> at a rate of <NUM>/min was determined as the melting point. However, when the endotherm peak at the re-heating was difficult to be detected because it is broad, the peak of the endotherm peak of the first round was determined as the melting point. The measured results are summarized in Table <NUM>.

The wholly aromatic liquid crystalline polyester resins obtained from the Examplesand Comparative Examples were heat melted at a temperature of the melting point to melting point + <NUM> and injection molded to make flat plate test specimens of <NUM> × <NUM> × <NUM>. These flat plate test specimens were cut into a width of <NUM> for tensile mode to prepare strip specimens of <NUM> × <NUM> × <NUM>. The center part of the flat plate test specimen was cut into <NUM> × <NUM> for compression mode to prepare plate like specimens of <NUM> × <NUM> × <NUM>.

The volume expansion coefficient (MD line expansion coefficient + TD line expansion coefficient + thickness line expansion coefficient) at <NUM> to <NUM> of these specimens were measured by using a thermomechanical analysis device (manufactured by Hitachi High-Tech Science Corporation, product name: TMA7000). MD direction and TD direction was evaluated in tensile mode and thickness direction in compression mode. The measured results are summarized in Table <NUM>.

Melt viscosity at a temperature of the melting point + <NUM> of the wholly aromatic liquid crystalline polyester resins obtained from the Examples and Comparative Examples were measured in accordance with JIS K7199 by using a capillary rheometer viscometer (manufactured by Toyo Seiki Seisaku-sho. The measured results are summarized in Table <NUM>.

The wholly aromatic liquid crystalline polyester resins obtained from the Examples and Comparative Examples were heat melted at a temperature of the melting point to melting point + <NUM> and injection molded to make flat plate test specimens of <NUM> × <NUM> × <NUM>. These flat plate test specimens were cut into a width of <NUM> for tensile mode to prepare strip specimens of <NUM> × <NUM> ×<NUM>. <NUM> (<NUM> in MD direction and <NUM> in TD direction). The glass transition point of the wholly aromatic liquid crystalline polyester resin was obtained from a peak top temperature of tan D obtained by dynamic viscoelasticity measurement in tensile mode by using a dynamic viscoelasticity measurement device (manufactured by Hitachi High-Tech Science Corporation, product name: DMA7100). The measured results are summarized in Table <NUM>.

Next, the second embodiment of the present invention will be described in details with the aid of the Examples and Comparative Examples.

To a polymerization vessel with a stirring blade, <NUM> mol % of <NUM>-hydroxy-<NUM>-naphthoic acid (HNA), <NUM> mol % of <NUM>,<NUM>-dihydroxybiphenyl (BP), <NUM> mol % of terephthalic acid (TPA), and <NUM> mol % of <NUM>,<NUM>-naphthalene dicarboxylic acid (NADA) were added, and potassium acetate and magnesium acetate were feeded as the catalyst, and after carrying out nitrogen substitution by reducing the pressure of the polymerization vessel and injecting nitrogen for <NUM> times, acetic anhydride (<NUM> mol equivalent based on a hydroxyl group) was further added, the temperature elevated to <NUM>, and acetylation reaction was performed for <NUM> hours in a reflux state.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP27. <NUM> mol %, TPA21. <NUM> mol %, and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM> and the retention time to <NUM> hour; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol % and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, NADA <NUM> mol %, and isophthalic acid (IPA) <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, NADA <NUM> mol %, and IPA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA 17mol %, and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA 14mol %, and NADA 6mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA60 mol %, BP20 mol %, TPA12mol %, and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin N was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA <NUM> mol %, NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA5 mol %, and NADA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM> and the retention time to <NUM> hour; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA <NUM> mol %, BP <NUM> mol %, TPA2. <NUM> mol %, and NADA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to BP <NUM> mol %, TPA <NUM> mol %, p-hydroxybenzoic acid (HBA) <NUM> mol %, and IPA <NUM> mol %; then liquid crystalline property was confirmed in a similar manner as above.

A liquid crystalline polyester resin was obtained in a similar manner as Example <NUM>-<NUM>, except that the monomer feed was changed to HNA 27mol % and HBA <NUM> mol %, and the final temperature of solid state polymerization was selected to <NUM>; then liquid crystalline property was confirmed in a similar manner as above.

Melt elongation property of the wholly aromatic liquid crystalline polyester resins obtained by the Examples and Comparative Examples was evaluated by measuring the elongation ratio of the melt strands. In particular, the wholly aromatic liquid crystalline polyester resin was melted under the conditions in which the temperature was the melting point of the liquid crystalline polyester resin + <NUM> and the extrusion rate of the plunger was <NUM> / min (=an extrusion rate when the shear rate applied to the resin when passing capillary is <NUM>-<NUM>) by using CAPILOGRAPH 1D manufactured by Toyo Seiki Seisaku-sho. (a rheometer with a barrel inner diameter of <NUM>), capillary with inner diameter of <NUM>, and extruded as a strand. The extruded melt strand was withdrawn with a wind-up roller via a pulley to measure the elongation ratio (= withdrawing rate at the end of measurement (m/min) / extrusion rate converted into the time when passing the capillary (m/min)). With respect to the withdrawing rate, the initial rate was <NUM> / min which was increased at the rate of <NUM> / min<NUM>, and the end of measurement was when the withdrawing rate reached <NUM> / min, which was the measuring limit of the device, or when the melt strand fractured. These measured results are summarized in Tables <NUM> and <NUM>. Also, the tensile force (=melt tensile force) of the melt strands at the end of measurement is summarized in Tables <NUM> and <NUM>. Those of which the melt strand could not be appropriately set up on the series of pulley and the wind-up roller due to lack of the melt elongation property, melt viscosity, or melt tensile force, or which measurement was not possible because the melt elongation property was below the measuring limit of the device was marked as "-".

The wholly aromatic liquid crystalline polyester resins obtained from the Examples and Comparative Examples were heat melted at a condition in which the temperature was from the melting point to melting point + <NUM> and injection molded to make flat plate test specimens of <NUM> × <NUM> × <NUM>. With respect to the dielectric tangent in the in-plane direction of these specimens, dielectric tangent of frequency of <NUM> was measured by a split post dielectric resonator method (SPDR method), using Network Analyzer N5247A from Keysight Technoligies.

The wholly aromatic liquid crystalline polyester resins obtained from Example <NUM>-<NUM> and Comparative Examples <NUM>-<NUM> and <NUM>-<NUM> were heat melted at a condition in which the temperature was from the melting point to melting point + <NUM> and injection molded to make flat plate samples of <NUM> × <NUM> × <NUM>. Subsequently, square flat plates in <NUM> square were cut from the center of these flat plate samples to make test specimens. These test specimens were loaded on to a resonator for <NUM> at Graduate School of Engineering, Utsunomiya University, Kogami Lab. & Shimizu Lab. , and by cylindrical cavity resonator method, the dielectric tangent of frequency of <NUM> was measured at room temperature. (Although a resonator for <NUM> was used, the actual measurement frequency was at around <NUM> from the resonance property of the material). The measured results are summarized in Table <NUM>. Also, the dielectric tangent measured at various frequencies in the similar procedure by using a cylindrical cavity resonator with different set up frequencies is shown in <FIG>.

The wholly aromatic liquid crystalline polyester resins obtained from Example <NUM>-<NUM> and Comparative Examples <NUM>-<NUM> and <NUM>-<NUM> were heat melted at a condition in which the temperature was from the melting point to melting point + <NUM> and injection molded to make flat plate samples of <NUM> × <NUM> × <NUM>. Subsequently, square flat plates in <NUM> square were cut from the center of these flat plate samples to make test specimens. These test specimens were loaded on to a resonator for <NUM> at Graduate School of Engineering Utsunomiya University, Kogami Lab. & Shimizu Lab. , and by cylindrical cavity resonator method, the dielectric tangent of frequency of <NUM> was measured while changing the measuring temperature. (Although a resonator for <NUM> was used, the actual measurement frequency was at <NUM> from the resonance property of the material). The measuring method in details is as follows. The resonator to which the specimen was set was arranged in a constant-temperature tank, and after setting the set-up temperature of the constant-temperature tank to <NUM>, <NUM> hours elapsed. Thereafter, the constant-temperature tank was set to <NUM> and the temperature inside the tank was left to naturally fall, and the dielectric tangent was measured at this time every <NUM>. The results are shown in <FIG>. Further, the dielectric tangent at <NUM> and <NUM> and the rate of change of dielectric tangent from <NUM> to <NUM> are shown in Table <NUM>.

The melting points of the wholly aromatic liquid crystalline polyester resins obtained by the Examples and Comparative Examples were measured by a differential scanning calorimeter (DSC) manufactured by Hitachi High-Tech Science Corporation. The temperature was elevated from room temperature to <NUM> - <NUM> at a rate of temperature increase of <NUM> / min to melt the polymer completely, and then the temperature was lowered to <NUM> at a rate of <NUM> /min, and an endotherm peak obtained when further elevating the temperature to <NUM> at a rate of <NUM> /min was determined as the melting point (Tm<NUM>). However, when the endotherm peak at the re-heating was difficult to be detected because it is broad, the peak of the endotherm peak of the first round (Tm<NUM>) was determined as the melting point (C). The measured results are summarized in Tables <NUM> and <NUM>.

The melt viscosity(Pa·s) at the temperature of the melting point + <NUM> in a shear rate of <NUM>-<NUM> of the wholly aromatic liquid crystalline polyester resins obtained by the Examples and Comparative Examples were measured in accordance with JIS K7199 by using a capillary rheometer viscometer (CAPILOGRAPH 1D manufactured by Toyo Seiki Seisaku-sho. ) and capillary with inner diameter of <NUM>. The measured results are summarized in Tables <NUM> and <NUM>.

Claim 1:
A wholly aromatic liquid crystalline polyester resin comprising,
structural unit (I) derived from <NUM>-hydroxy-<NUM>-naphthoic acid,
structural unit (II) derived from an aromatic diol compound,
structural unit (III) derived from an aromatic dicarboxylic compound, wherein
structural unit (III) comprises structural unit (III A) derived from terephthalic acid, structural unit (III B) derived from <NUM>,<NUM>-naphthalene dicarboxylic acid and structural unit (III C) derived from isophthalic acid, wherein
the composition ratio (mol %) of said structural units is characterized by satisfying the following conditions: <MAT> <MAT> <MAT> <MAT> <MAT>
wherein the wholly aromatic liquid crystalline polyester resin has a dielectric tangent in measurement frequency <NUM> as measured according to the description of <NUM> × <NUM>-<NUM> or less, and
wherein the wholly aromatic liquid crystalline polyester resin has a melt tensile force according to the description of <NUM> mN or more.