Liquid crystal polyester resin, molded article, and electrical and electronic parts

Abstract

[Problem] To provide a liquid crystal polyester resin with excellent processability and stability during melting. [Solution] The liquid crystal polyester resin based on the present invention comprises only a constituent unit (I) derived from an aromatic hydroxycarboxylic acid and a constituent unit (II) derived from a dicarboxylic acid, and is obtained by solid-state polymerization. The liquid crystal polyester resin is characterized in that the composition ratio of the constituent unit (II) relative to the constituent unit (I) is more than 0 mol% and less than 2.0 mol%.

Description

Technical Field

[0001] This invention relates to a liquid crystal polyester resin, and more specifically to a liquid crystal polyester resin with excellent processability and stability when melted, a molded article comprising the liquid crystal polyester resin, and an electrical and electronic component comprising the molded article. Background Technology

[0002] A common industrial manufacturing method for high-heat-resistant liquid crystal polyester resins classified as super engineering plastics is melt polymerization, which uses aromatic hydroxycarboxylic acids, aromatic diols, and aromatic dicarboxylic acids as main monomers and uses acetic anhydride to melt polymerize these. Melt polymerization is a method that promotes the formation of ester bonds by heating and stirring a fluid reaction system, and the reaction progress can be monitored by the amount of acetic acid distilled as a byproduct. Condensation polymerization, as a type of successive polymerization, has the property that the degree of polymerization increases sharply as the reaction progress approaches 100%. On the other hand, since it is an equilibrium reaction, it is necessary to promote the distillation of acetic acid as a byproduct in order to bring the reaction progress close to 100%. As a method to promote the distillation of acetic acid in melt polymerization, a method of depressurizing the reaction system is known. The method of obtaining a liquid crystal polyester resin with a target degree of polymerization by depressurizing at the end of the reaction is widely used in industry (Patent Document 1). In this method, the timing of reaching the target degree of polymerization, i.e., the target melt viscosity, as the reaction endpoint, can be calculated based on the power consumed by the stirring blades of the reaction system, i.e., the stirring motor, or the applied torque value. The reason is that as the reaction proceeds, the melt viscosity of the produced polymer increases, but in order to maintain the stirring of the high melt viscosity fluid, the load in the stirring motor also increases. By effectively utilizing this relationship, manufacturers of liquid crystal polyester resins can produce liquid crystal polyester resins with high reproducibility within a certain narrow quality specification centered on the target melt viscosity.

[0003] On the other hand, when using only melt polymerization, there is an upper limit to the melt viscosity that can be produced. After melt polymerization, the manufactured liquid crystal polyester resin needs to be transferred from the reaction furnace to the next process. However, when the melt viscosity of the liquid crystal polyester resin exceeds a certain value, its flowability or mobility decreases. As a result, problems such as the manufactured liquid crystal polyester resin remaining in the reaction furnace or solidifying in the piping occur, leading to decreased production efficiency or equipment damage (Patent Document 1). Therefore, when using only melt polymerization, it is limited to producing high heat-resistant liquid crystal polyester resins with relatively low melting points and relatively low melt viscosity. However, melt polymerization has the following advantages: by effectively utilizing the power consumption or torque value of the stirring motor, it is possible to quantitatively and timely determine whether the melt viscosity in industrial manufacturing meets the quality specifications, thus enabling high-precision manufacturing.

[0004] In manufacturing liquid crystal polyester resins with melt viscosity exceeding the upper limit of melt polymerization, a solid-state polymerization method is applied (Patent Document 2) by further heating the polymer obtained by melt polymerization in a solid state. The solid-state polymerization method involves feeding liquid crystal polyester resin in a solid state, such as powder, fragments, or granules, into a heating furnace and heating it to above the glass transition point and below the melting point, thereby causing polycondensation within the solid. Since the liquid crystal polyester resin remains in a solid state throughout the reaction, there are no limitations such as the upper limit of the achievable melt viscosity that occur in melt polymerization. Because it is less likely to cause resin residue in the reaction furnace or solidification in the piping, it is a suitable method for manufacturing high-heat-resistant / high-viscosity liquid crystal polyester resins. However, compared to melt polymerization, solid-state polymerization is inferior in terms of controlling the rate of reaction, i.e., controlling the timing of reaching the target melt viscosity. In solid-state polymerization, the reaction continues in a solid state throughout, making it impossible to monitor the melt viscosity at the reaction site. As a countermeasure, the following strategy is adopted: During the repeated production of a specific liquid crystal polyester resin, the temperature and time profile of solid-state polymerization, and the polymerization progress of the liquid crystal polyester resin when applying the profile, are controlled to optimize the reaction conditions, thereby ensuring that the melt viscosity of the liquid crystal polyester resin to be produced meets quality specifications. However, in the case of large-scale manufacturing facilities, the influence of the external environment or the stability of the supply of utilities such as electricity on the manufacturing day cannot be ignored. For example, seasonal changes in external temperature can affect the melt temperature or melt velocity in the reaction furnace, making it difficult to achieve the set profile. As a measure to address such fluctuations, a portion of the liquid crystal polyester resin can be separated from the reaction system and its melt viscosity measured using a separate measuring device. However, this measure requires a certain amount of time, and the reaction will continue during the measurement period. Furthermore, as mentioned above, condensation polymerization at high reaction rates causes a sharp increase in viscosity; therefore, producing a resin with a melt viscosity within quality specifications via solid-state polymerization is more difficult than via melt polymerization.

[0005] In particular, polymers with a high proportion of aromatic hydroxycarboxylic acids in the monomers constituting liquid crystal polyester resins tend to have more difficult melt viscosity adjustments using solid-state polymerization. This is because aromatic hydroxycarboxylic acids, unlike aromatic diols and aromatic dicarboxylic acids, can undergo homopolymerization using only one monomer, resulting in a higher degree of polycondensation reaction.

[0006] Furthermore, in recent years, with the increase in information communication volume in the communications field, the use of high-frequency signals in electronic and communication devices has increased. In particular, the use of signals with 10... 9The signals mentioned above are in the gigahertz (GHz) frequency band. For example, GHz signals are used in the automotive field. Specifically, millimeter-wave radar and quasi-millimeter-wave radar, which are installed for the purpose of preventing car collisions, use high-frequency signals of 76 GHz to 79 GHz and 24 GHz respectively, and further widespread adoption is expected in the future.

[0007] However, as the frequency of the signal used increases, the quality of the output signal may deteriorate, potentially leading to misidentification of information; that is, transmission loss increases. Transmission loss includes conductor loss caused by the conductor itself and dielectric loss caused by the insulating resin used in electrical and electronic components such as the substrate in electronic or communication equipment. Conductor loss is proportional to the 0.5 power of the operating frequency, while dielectric loss is proportional to the 1st power of the frequency. Therefore, in high-frequency bands, especially the GHz band, the impact of dielectric loss is significant. Furthermore, dielectric loss increases proportionally to the dielectric loss tangent of the resin; therefore, to prevent information degradation, resins with low dielectric loss tangents are required. Furthermore, processability during the manufacturing of molded articles is also required. For example, Patent Document 3 reports a liquid crystal polyester resin with low dielectric loss tangent and injection molding adaptability as a liquid crystal polyester resin, using 6-hydroxy-2-naphthoic acid from aromatic hydroxycarboxylic acids as the main monomer.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: International Publication No. 2018 / 139393

[0011] Patent Document 2: International Publication No. 2018 / 8612

[0012] Patent Document 3: Japanese Patent Application Publication No. 2017-179127 Summary of the Invention

[0013] The problem that the invention aims to solve

[0014] The report states that in manufacturing using only melt polymerization, stability is achieved by deviating the mass ratio of the aromatic diol to the aromatic dicarboxylic acid from 1:1 and by inhibiting the reaction during melt processing after the liquid crystal polyester resin is manufactured (Patent Document 1). However, the method described in Patent Document 1 (the selection of the added monomers and the range of their amounts) is insufficient from the viewpoints of dielectric properties, melt processability, and melt stability of the obtained liquid crystal polyester resin obtained by performing solid-state polymerization instead of melt polymerization.

[0015] Therefore, an object of the present invention is to provide a liquid crystal polyester resin exhibiting excellent processability and melt stability when melted in a liquid crystal polyester resin manufactured by solid-state polymerization. Furthermore, another object of the present invention is to provide a molded article comprising the liquid crystal polyester resin and an electrical and electronic component comprising the molded article.

[0016] Methods for solving problems

[0017] That is, according to the present invention, the following invention is provided.

[0018] [1] A liquid crystal polyester resin comprising only a constituent unit (I) derived from an aromatic hydroxycarboxylic acid and a constituent unit (II) derived from a dicarboxylic acid, obtained by solid-state polymerization, wherein the liquid crystal polyester resin is characterized in that:

[0019] The composition ratio of the constituent unit (II) relative to the constituent unit (I) is more than 0 mol% and less than 2.0 mol%.

[0020] [2] According to the liquid crystal polyester resin of [1], wherein the constituent unit (I) comprises constituent units derived from three or more aromatic hydroxycarboxylic acids.

[0021] [3] According to the liquid crystal polyester resin of [1] or [2], wherein the constituent unit (I) comprises at least a constituent unit (A) derived from p-hydroxybenzoic acid and a constituent unit (B) derived from 6-hydroxy-2-naphthoic acid.

[0022] [4] According to the liquid crystal polyester resin of [3], wherein the constituent unit (B) has the highest composition ratio among the constituent units (I).

[0023] [5] According to the liquid crystal polyester resin of [3] or [4], wherein the composition of the constituent unit (A) in the constituent unit (I) is more than that of the constituent unit (A).

[0024] [6] The liquid crystal polyester resin according to any one of [3] to [5], wherein the constituent unit (I) further comprises a constituent unit (C) derived from an aromatic hydroxycarboxylic acid other than the constituent unit (A) and the constituent unit (B).

[0025] Relative to the entirety of the constituent unit (I) derived from aromatic hydroxycarboxylic acids, the compositional ratio (molar %) of the constituent units (A) to (C) satisfies the following condition:

[0026] 15 mol% ≤ Constituent Unit (A) ≤ 30 mol%

[0027] 60 mol% ≤ Constituent Unit (B) ≤ 80 mol%

[0028] 0.1 mol% ≤ constitutive unit (C) ≤ 10 mol%.

[0029] [7] The liquid crystal polyester resin according to [6], wherein the constituent unit (C) is a constituent unit derived from at least one of the group consisting of m-hydroxybenzoic acid, 6-hydroxynicotinic acid and 4'-hydroxy-4-biphenylcarboxylic acid.

[0030] [8] The liquid crystal polyester resin according to any one of [1] to [7], wherein the constituent unit (II) is derived from an aromatic dicarboxylic acid.

[0031] [9] The liquid crystal polyester resin according to any one of [1] to [8], wherein the constituent unit (II) is derived from terephthalic acid.

[0032]

[10] The liquid crystal polyester resin according to any one of [1] to [9], wherein the dielectric loss tangent at a measured frequency of 10 GHz is 1.0 × 10⁻⁶. -3 the following.

[0033]

[11] The liquid crystal polyester resin according to any one of [1] to

[10] , wherein the mass reduction when held at 370°C under a nitrogen flow for 30 minutes is less than 0.50% by mass.

[0034]

[12] The liquid crystal polyester resin according to any one of [1] to

[11] , wherein the melt viscosity at 100 / s from melting point to melting point +30°C is 10 Pa·s or more.

[0035]

[13] A fibrous molded article comprising a liquid crystal polyester resin according to any one of [1] to

[12] .

[0036]

[14] A sheet-like molded article comprising a liquid crystal polyester resin according to any one of [1] to

[12] .

[0037]

[15] An injection-molded article comprising a liquid crystal polyester resin according to any one of [1] to

[12] .

[0038]

[16] An electrical and electronic component comprising a molded article according to

[13] .

[0039]

[17] An electrical and electronic component comprising a molded article according to

[14] .

[0040]

[18] An electrical and electronic component comprising a molded article according to

[15] .

[0041] The effects of the invention

[0042] This invention provides a liquid crystal polyester resin with excellent processability and stability during melting. Furthermore, by using the liquid crystal polyester resin of this invention, molded articles can be obtained that achieve suppression of escape gas generation, hue improvement, and low dielectric loss tangent. Therefore, when used as an article, it can prevent degradation of the output signal quality in electrical and electronic equipment or communication equipment using high-frequency signals.

[0043] In particular, in this invention, by adding a small amount of dicarboxylic acid to the aromatic hydroxycarboxylic acid as the main monomer, the hydroxyl / carboxyl group ratio in the polymer system is slightly dissociated from 1, which can suppress the reaction rate in solid-state polymerization, especially the reaction rate at high temperatures where the reaction proceeds rapidly. Regarding this suppression, the reaction itself can preferably be moderately suppressed within the range where the liquid crystal polyester resin can reach the high viscosity band without significantly reducing the reaction time. This allows for a more moderate reaction pace at the end of the solid-state polymerization reaction when separation and viscosity evaluation are performed, and makes it easier to set the reaction cessation time after viscosity evaluation.

[0044] Furthermore, by adding a small amount of dicarboxylic acid, the dielectric properties and other physical properties of the obtained liquid crystal polyester resin can be improved. Specifically, compared with liquid crystal polyester resins containing only constituent units derived from aromatic hydroxycarboxylic acids, the dielectric loss tangent can be reduced within the same viscosity band / degree of polymerization band. This, in turn, reduces residual sublimation after manufacturing and gases generated due to post-manufacturing heating (escape gases). Escape gases are related to foaming or the generation of foreign matter during processing of the manufactured liquid crystal polyester resin during melting or subsequent processing, and are therefore related to improvements in thermal stability during processing. Attached Figure Description

[0045] [ Figure 1 [This is a graph showing the relationship between melt viscosity and the final temperature reached by solid-phase polymerization in the series of Examples 2, Comparative Examples 1 to 3.]

[0046] [ Figure 2 [This is a graph showing the relationship between melting point and final temperature reached by solid-state polymerization in the series of Examples 2 and Comparative Examples 1 to 3.]

[0047] [ Figure 3 [ ] is a graph showing the relationship between melt viscosity and melting point in the series of Examples 2 and Comparative Examples 1 to 3.

[0048] [ Figure 4 [This is a graph showing the relationship between melt viscosity and the final temperature reached by solid-state polymerization in the series of Examples 1, 2, and 1 Comparative Examples.]

[0049] [ Figure 5[This is a graph showing the relationship between melting point and final temperature reached by solid-state polymerization in the series of Examples 1, 2, and 1 Comparative Examples.]

[0050] [ Figure 6 [ ] is a graph showing the relationship between melt viscosity and melting point in the series of Examples 1, 2, and 1 of Comparative Examples. Detailed Implementation

[0051] (Liquid crystal polyester resin)

[0052] The liquid crystal polyester resin based on the present invention comprises only a constituent unit (I) derived from an aromatic hydroxycarboxylic acid and a constituent unit (II) derived from a dicarboxylic acid, and is obtained by solid-state polymerization. Furthermore, the liquid crystal polyester resin based on the present invention can be an element or a mixture (polymer blend).

[0053] In the liquid crystal polyester resin based on the present invention, by including a small amount of dicarboxylic acid-derived constituent units (II) relative to the constituent units (I) derived from aromatic hydroxycarboxylic acids contained in a proportion of 98.0 mol% or more and less than 100 mol% relative to all constituent units, a liquid crystal polyester resin with excellent processability and stability during melt flow can be obtained. Furthermore, by using the liquid crystal polyester resin of the present invention, molded articles that can achieve suppression of escape gas generation, hue improvement, and low dielectric loss tangent can be obtained.

[0054] The upper limit of the dielectric loss tangent of the liquid crystal polyester resin based on the present invention at a measurement frequency of 10 GHz is preferably 1.0 × 10⁻⁶. -3 The following is more preferably 0.95×10 -3 The following is more preferably 0.90×10 -3 The preferred value is 0.85 × 10⁻⁶. -3 the following.

[0055] By setting the dielectric loss tangent of the liquid crystal polyester resin based on the present invention within the stated value range, molded articles with reduced dielectric loss can be manufactured, thus preventing degradation of the output signal quality in electrical and electronic equipment or communication equipment using high-frequency signals when used as articles.

[0056] Furthermore, in this specification, the dielectric loss tangent of the liquid crystal polyester resin at 10 GHz can be measured using a network analyzer such as the Keysight Technologies N5247A at an environment of 23°C and 50% RH by the split post dielectric resonator method (SPDR).

[0057] The lower limit of the melt viscosity of the liquid crystal polyester resin based on the present invention, measured under conditions of melting point to melting point +30°C and shear rate of 100 / s, is 10 Pa·s or more, preferably 15 Pa·s or more, more preferably 20 Pa·s or more, further preferably 30 Pa·s or more, and even more preferably 50 Pa·s or more. Furthermore, the upper limit of the melt viscosity is preferably 500 Pa·s or less, more preferably 400 Pa·s or less, further preferably 300 Pa·s or less, and even more preferably 250 Pa·s or less. By setting the melt viscosity of the liquid crystal polyester resin based on the present invention within the aforementioned numerical range, a liquid crystal polyester resin that exhibits excellent processability when melted at high temperatures, and also possesses a specific viscosity band at high temperatures and reduces the dielectric loss tangent, can be obtained.

[0058] Furthermore, in this specification, the viscosity of the liquid crystal polyester resin can be measured using a capillary rheometer according to Japanese Industrial Standards (JIS) K7199.

[0059] Taking heat resistance into consideration, the lower limit of the melting point of the liquid crystal polyester resin based on the present invention is preferably 280°C or higher, more preferably 290°C or higher, even more preferably 295°C or higher, even more preferably 300°C or higher, and most preferably 305°C or higher. In addition, the upper limit is not particularly limited, but is preferably 350°C or lower, more preferably 340°C or lower, even more preferably 330°C or lower, and even more preferably 320°C or lower.

[0060] By setting the melting point of the liquid crystal polyester resin based on the present invention within the stated numerical range, the melt viscosity of 100 / s at 330°C can be easily adjusted to the desired numerical range. In addition, the heat resistance of molded articles made using the liquid crystal polyester resin to heat processing can be improved.

[0061] Furthermore, in this specification, the melting point of the liquid crystal polyester resin is a value measured using a differential scanning calorimeter (DSC). Specifically, according to JIS-7121, the liquid crystal polyester resin is heated from room temperature to 360°C at a heating rate of 10°C / min to completely melt it, then cooled to 30°C at a heating rate of 10°C / min. The peak of the resulting heating peak is designated as the crystallization point (Tc), and then the temperature is increased to 360°C at a heating rate of 10°C / min. The peak of the resulting endothermic peak is designated as the melting point (Tm).

[0062] Taking into account practical heat resistance, the lower limit of the deflection temperature under load (DTUL) of the liquid crystal polyester resin based on the present invention is preferably 220°C or higher, more preferably 230°C or higher, even more preferably 240°C or higher, even more preferably 245°C or higher, and most preferably 250°C or higher.

[0063] By setting the load flexural temperature (DTUL) of the liquid crystal polyester resin based on the present invention within the stated numerical range, the practical heat resistance of molded articles made using the liquid crystal polyester resin to heat processing can be improved. With these preferred practical heat resistance properties, the heat processing following melt processing of the liquid crystal polyester (processing using molten solder or hot pressing) can be carried out without material deformation.

[0064] Furthermore, in this specification, the load flexural temperature (DTUL) of the liquid crystal polyester resin is a value obtained by measuring a load of 0.45 MPa along the edgewise (applied to the 12.5 mm × 2 mm surface) using a bending test piece (80 mm × 12.5 mm × 2 mm) produced by injection molding, in accordance with American Society for Testing Materials (ASTM) D648.

[0065] The mass reduction of the liquid crystal polyester resin based on the present invention when held at 370°C under nitrogen flow for 30 minutes is preferably 0.60% by mass or less, more preferably 0.50% by mass or less, even more preferably 0.40% by mass or less, and even more preferably 0.35% by mass or less.

[0066] If the mass of the liquid crystal polyester resin based on the present invention is reduced to within the stated numerical range, the liquid crystal polyester resin exhibits excellent stability during melting.

[0067] The liquid crystal properties of the liquid crystal polyester resin based on the present invention can be confirmed by the following method: using a microscope heating stage (trade name: 10083L) manufactured by Japan High-Tech Co., Ltd., or a polarizing microscope (trade name: DS-Ri2) manufactured by Nikon Co., Ltd., the liquid crystal polyester resin is heated and melted on the microscope heating stage, and then the presence or absence of optical anisotropy is observed.

[0068] The constituent units contained in the liquid crystal polyester resin based on the present invention will be described in detail below.

[0069] (Derived from the building block (I) of aromatic hydroxycarboxylic acids)

[0070] The constituent unit (I) derived from aromatic hydroxycarboxylic acids preferably includes constituent units derived from three or more aromatic hydroxycarboxylic acids. Furthermore, the constituent unit (I) derived from aromatic hydroxycarboxylic acids preferably includes at least a constituent unit (A) derived from p-hydroxybenzoic acid and a constituent unit (B) derived from 6-hydroxy-2-naphthoic acid, more preferably it also includes constituent units (A) and (C) derived from aromatic hydroxycarboxylic acids other than constituent units (B). In the liquid crystal polyester resin, the composition ratio of constituent unit (B) is preferably the largest, and the composition ratio of constituent unit (A) is preferably the second largest.

[0071] (Derived from the building block (A) of aromatic hydroxycarboxylic acids)

[0072] The building block (A) derived from aromatic hydroxycarboxylic acids is derived from p-hydroxybenzoic acid (HBA). Monomers that provide building block (A) include p-hydroxybenzoic acid, its acetylated derivatives, ester derivatives, acyl halides, etc.

[0073] Regarding the composition ratio (mol%) of the constituent unit (A) in the liquid crystal polyester resin, from the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin, the lower limit value relative to the total constituent unit (I) derived from aromatic hydroxycarboxylic acid is preferably 15 mol% or more, more preferably 17 mol% or more, further preferably 20 mol% or more, further preferably 22 mol% or more, and the upper limit value is preferably 30 mol% or less, more preferably 29 mol% or less, further preferably 28 mol% or less, and further preferably 27 mol% or less. By introducing the constituent unit within the above numerical range, improved heat resistance and formability can be achieved.

[0074] (Based on the building block (B) of aromatic hydroxycarboxylic acids)

[0075] The building block (B) derived from aromatic hydroxycarboxylic acids is derived from 6-hydroxy-2-naphthoic acid (HNA). Monomers that provide building block (B) include 6-hydroxy-2-naphthoic acid, its acetylated derivatives, ester derivatives, acyl halides, etc.

[0076] Regarding the composition ratio (mol%) of the constituent unit (B) in the liquid crystal polyester resin, from the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin, the lower limit value relative to the total constituent unit (I) derived from aromatic hydroxycarboxylic acid is preferably 60 mol% or more, more preferably 65 mol% or more, further preferably 67 mol% or more, further preferably 70 mol% or more, and the upper limit value is preferably 80 mol% or less, more preferably 78 mol% or less, further preferably 76 mol% or less, and further preferably 75 mol% or less. By introducing the constituent unit within the above numerical range, improved low dielectric loss tangent and heat resistance can be achieved.

[0077] (Derived from the building block (C) of aromatic hydroxycarboxylic acids)

[0078] The constituent unit (C) derived from an aromatic hydroxycarboxylic acid is a constituent unit derived from an aromatic hydroxycarboxylic acid other than constituent unit (A) and constituent unit (B). The constituent unit (C) is preferably a constituent unit derived from at least one selected from the group consisting of m-hydroxybenzoic acid (mHBA), 6-hydroxynicotinic acid (HNIA), and 4'-hydroxy-4-biphenyl carboxylic acid (HPBA). Among these, a constituent unit derived from m-hydroxybenzoic acid is more preferred. Examples of monomers providing the constituent unit (C) include these monomers, as well as their acetylated, ester derivatives, acyl halides, etc.

[0079] Regarding the composition ratio (mol%) of the constituent units (C) in the liquid crystal polyester resin, from the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin, the lower limit value relative to the total constituent units (I) derived from aromatic hydroxycarboxylic acids is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, further preferably 1.0 mol% or more, further preferably 1.5 mol% or more, and the upper limit value is preferably 10 mol% or less, more preferably 7.0 mol% or less, further preferably 5.0 mol% or less, and further preferably 3.0 mol% or less. By introducing the constituent units within the above numerical range, both improved heat resistance and excellent formability can be achieved.

[0080] The composition ratio (molar percentage) of constituent units (A) to (C) in the liquid crystal polyester resin, relative to the constituent unit (I) derived from aromatic hydroxycarboxylic acid as a whole, preferably satisfies the following conditions:

[0081] 15 mol% ≤ Constituent Unit (A) ≤ 30 mol%

[0082] 60 mol% ≤ Constituent Unit (B) ≤ 80 mol%

[0083] 0.1 mol% ≤ constitutive unit (C) ≤ 10 mol%

[0084] More preferably, the following conditions must be met:

[0085] 17 mol% ≤ Constituent Unit (A) ≤ 29 mol%

[0086] 65 mol% ≤ constituent unit (B) ≤ 78 mol%

[0087] 0.5 mol% ≤ constitutive unit (C) ≤ 7.0 mol%

[0088] Furthermore, it is preferable to satisfy the following conditions:

[0089] 20 mol% ≤ Constituent Unit (A) ≤ 28 mol%

[0090] 67 mol% ≤ Constituent Unit (B) ≤ 76 mol%

[0091] 1.0 mol% ≤ Constituent unit (C) ≤ 5.0 mol%

[0092] Furthermore, it is more preferable to satisfy the following conditions:

[0093] 22 mol% ≤ Constituent Unit (A) ≤ 27 mol%

[0094] 70 mol% ≤ Constituent Unit (B) ≤ 75 mol%

[0095] 1.5 mol% ≤ constitutive unit (C) ≤ 3.0 mol%.

[0096] (Derived from the building block (II) of dicarboxylic acid)

[0097] The constituent unit (II) derived from dicarboxylic acid is preferably a constituent unit derived from dicarboxylic acid as represented by the following formula (1), and more preferably a constituent unit derived from aromatic dicarboxylic acid. Furthermore, the constituent unit (II) may contain only one type or may contain two or more types.

[0098] [Chemistry 1]

[0099]

[0100] In the formula, Ar 3The alkyl group may have substituents as needed, but is preferably a divalent alkyl group having an aromatic ring. Examples of alkyl groups having an aromatic ring include phenyl, biphenyl, 4,4'-isopropylidene diphenyl, naphthyl, anthraceneyl, and phenanthrene. Examples of substituents include hydrogen, alkyl, alkoxy, and fluorine. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 5. Furthermore, it may be a straight-chain alkyl group or a branched-chain alkyl group. The alkoxy group preferably has 1 to 10 carbon atoms, more preferably 1 to 5.

[0101] Examples of monomers providing constituent unit (II) include terephthalic acid (TPA), isophthalic acid (IPA), 2,6-naphthalene dicarboxylicacid (NADA), cyclohexane dicarboxylic acid (CHDA), and their acylates, ester derivatives, acyl halides, etc. Constituent unit (D) is preferably derived from terephthalic acid. By selecting an appropriate type of constituent unit (II), a viscosity elongation suppression effect in solid-state polymerization can be obtained, and the resulting liquid crystal polyester resin can be manufactured with excellent thermal, mechanical, and dielectric properties.

[0102] The composition ratio (mol%) of the constituent unit (II) in the liquid crystal polyester resin is greater than 0 mol% and less than 2 mol% relative to the constituent unit (I). From the viewpoint of reducing the dielectric loss tangent of the liquid crystal polyester resin, the lower limit of the composition ratio (mol%) of the constituent unit (II) relative to the constituent unit (I) is preferably 0.1 mol% or more, more preferably 0.2 mol% or more, more preferably 0.3 mol% or more, more preferably 0.4 mol% or more, and the upper limit is preferably 1.8 mol% or less, more preferably 1.5 mol% or less, more preferably 1.2 mol% or less, and more preferably 0.9 mol% or less. By introducing the constituent unit within the numerical range below the upper limit, the polymerization of the liquid crystal polyester resin can be reliably carried out, while slowing down the polymerization rate. Therefore, solid-state polymerization can be carried out without causing melting or welding to the reactor during solid-state polymerization. As a result, a liquid crystal polyester resin with excellent thermal, mechanical, and dielectric properties can be obtained. Furthermore, by introducing the constituent unit within a numerical range above the lower limit, the solid-state polymerization of the liquid crystal polyester resin can be reliably suppressed, and the polymerization speed can be adjusted accordingly to the objective.

[0103] (Manufacturing method of liquid crystal polyester resin)

[0104] The liquid crystal polyester resin of the present invention can be manufactured by the following method (two-stage polymerization), the method comprising: a step of melt polymerization of monomers providing constituent unit (I) and monomers providing constituent unit (II) to obtain a polymer; and a step of solid-state polymerization of the polymer to obtain the liquid crystal polyester resin.

[0105] Regarding melt polymerization, from the viewpoint of efficiently obtaining liquid crystal polyester resin, it is preferable to have 1.03 to 1.15 molar equivalents of acetic anhydride present relative to all hydroxyl groups of all monomers and to carry out the process under reflux of acetic acid, and more preferably to have 1.03 to 1.10 molar equivalents of acetic anhydride present and to carry out the process under reflux of acetic acid.

[0106] The reaction temperature for melt polymerization is preferably in the range of (melting point -20)℃ to (melting point +70)℃, and more preferably in the range of (melting point +20)℃ to (melting point +50)℃.

[0107] Melt polymerization is preferably carried out in the presence of a catalyst and in the absence of a solvent. The catalyst can be any known catalyst for polymer polymerization. Examples of catalysts include: metal salt catalysts such as potassium acetate, magnesium acetate, stannous acetate, lead acetate, sodium acetate, tetrabutyl titanate, and antimony trioxide; and organic compound catalysts such as nitrogen-containing heterocyclic compounds such as N-methylimidazole. The amount of catalyst used is not particularly limited, but is preferably (10 to 100) mg / mol of the total number of monomer moles.

[0108] In solid-state polymerization, the polymer obtained through melt polymerization can be cooled, solidified, and then pulverized to form powder or fragments. Alternatively, polymer strands obtained through melt polymerization can be granulated to form granules. The reaction temperature for solid-state polymerization is preferably below the melting point, preferably (melting point - 100) °C to (melting point - 10) °C. The reaction temperature for solid-state polymerization can be varied in stages, and the final temperature reached by solid-state polymerization is preferably (melting point - 50) °C to (melting point - 10) °C, more preferably (melting point - 40) °C to (melting point - 15) °C. Solid-state polymerization can be carried out while stirring, or it can be carried out in a static state without stirring.

[0109] The polymerization apparatus is not particularly limited, and it is preferable to use the reaction apparatus used in the reaction of general high-viscosity fluids. Examples of such reaction apparatus include: stirred tank type polymerization apparatus with stirring devices having anchor type, multi-stage type, spiral ribbon type, spiral shaft type, etc., or various shapes of these modified stirring blades; or mixing devices such as kneaders, roller mills, and Banbury mixers, which are generally used for mixing resins.

[0110] (Made product)

[0111] The molded article based on the present invention comprises the liquid crystal polyester resin of the present invention, and may also further comprise other liquid crystal polyester resins, other resins, and fillers. The content of resin components in the molded article (the total content of the liquid crystal polyester resin of the present invention, other liquid crystal polyester resins, and other resins) relative to the total amount of the molded article is preferably 30% by mass or more and 99% by mass or less, more preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and more preferably 55% by mass or more and 85% by mass or less.

[0112] (filler)

[0113] Examples of fillers include: carbon fiber, graphite, glass fiber, talc, mica, glass fragments, clay, sericite, calcium carbonate, calcium sulfate, calcium silicate, silicon dioxide, alumina, aluminum hydroxide, calcium hydroxide, graphite, potassium titanate, titanium dioxide, fluorocarbon fiber, fluorocarbon resin, barium sulfate, and various whiskers. These fillers can be used individually or in combination.

[0114] Relative to the total amount of the molded article, the filler content in the molded article is preferably 1% by mass or more and 70% by mass or less, more preferably 5% by mass or more and 60% by mass or less, further preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 45% by mass or less. When two or more fillers are included, it is preferable that their total content is within the aforementioned range. If the filler content in the molded article is within the aforementioned range, a molded article with superior mechanical properties can be obtained, and therefore is preferred.

[0115] (Other liquid crystal polyester resins besides the liquid crystal polyester resin of this invention)

[0116] As for other liquid crystal polyester resins, there are no particular limitations if they are liquid crystal polyester resins other than those described in this invention, and conventionally known liquid crystal polyester resins can be used. Preferred forms of other liquid crystal polyester resins include, for example, liquid crystal polyester resins having constituent units derived from hydroxycarboxylic acids. A particularly preferred form is a liquid crystal polyester resin containing 65 mol% to 80 mol% (preferably 70 mol% to 75 mol%) of p-hydroxybenzoic acid and 20 mol% to 35 mol% (preferably 25 mol% to 30 mol%) of 6-hydroxy-2-naphthoic acid. Furthermore, as other preferred forms, liquid crystal polyester resins that, in addition to having constituent units derived from hydroxycarboxylic acids, also contain at least one of constituent units derived from aromatic dicarboxylic acids and constituent units derived from aromatic diols can be included. As a particularly preferred form, a liquid crystal polyester resin containing 60 mol% to 80 mol% (preferably 65 mol% to 75 mol%) of p-hydroxybenzoic acid, 1 mol% to 5 mol% of 6-hydroxy-2-naphthoic acid, 0 mol% to 20 mol% (preferably 1 mol% to 15 mol%) of constituent units derived from aromatic dicarboxylic acids, and 0 mol% to 20 mol% (preferably 1 mol% to 15 mol%) of constituent units derived from aromatic diols can be listed here. Here, as constituent units derived from aromatic dicarboxylic acids, constituent units derived from at least one of 4,4'-dihydroxybiphenyl and hydroquinone can be listed. Furthermore, as constituent units derived from aromatic diols, constituent units derived from at least one of terephthalic acid, isophthalic acid, and 4'-hydroxy-4-biphenylcarboxylic acid can be listed. The composition ratio of each constituent unit is not limited to the preferred form and can be appropriately adjusted. In addition, other liquid crystal polyester resins can be used alone or in combination with two or more other types.

[0117] Relative to the total of 100 parts by weight of the liquid crystal polyester resin of the present invention and other liquid crystal polyester resins, the upper limit of the content of other liquid crystal polyester resins besides the liquid crystal polyester resin of the present invention in the molded article is preferably 90 parts by weight or less, more preferably 75 parts by weight or less, and even more preferably 50 parts by weight or less. The lower limit can be 1 part by weight or more, or 3 parts by weight or more, or 5 parts by weight or more.

[0118] (Resins other than liquid crystal polyester resin)

[0119] Without departing from the spirit of the invention, molded articles based on the invention may also contain resins other than liquid crystal polyester resin. Other resins include, for example: polyethylene terephthalate, polyethylene naphthalate, polyarylates, polycyclohexylene dimethylene terephthalate, and polybutylene terephthalate, etc.; polyethylene, polypropylene, and other polyolefin resins; cycloolefin polymers; polyvinyl chloride and other vinyl resins; polyacrylates; polymethyl methacrylate and other (meth)acrylic resins; polyphenylene ether resins; polyacetal resins; polyamide resins; polyimide and polyetherimide, etc.; polystyrene, high-impact polystyrene, acrylonitrile-styrene (AS) resin and acrylonitrile-butadiene-styrene (ABS) resin, etc.; thermosetting resins such as epoxy resins; cellulose resins; polyetheretherketone resins; fluoropolymers; and polycarbonate resins. These other resins may be used alone or in combination.

[0120] Regarding the content of resins other than liquid crystal polyester resin in the molded article, the upper limit is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, relative to the total of 100 parts by weight of the liquid crystal polyester resin and other liquid crystal polyester resins of the present invention.

[0121] (Other additives)

[0122] Without departing from the spirit of the invention, molded articles based on the invention may also contain other additives, such as colorants, dispersants, plasticizers, antioxidants, hardeners, flame retardants, heat stabilizers, ultraviolet absorbers, antistatic agents, and surfactants. These other additives may be used alone or in combination.

[0123] The shape of the molded article can be appropriately changed according to its application, and there are no particular limitations. Examples of shapes for molded articles include fibrous, plate-like, sheet-like, and rod-like forms.

[0124] The molded articles based on the present invention can be manufactured using a resin composition comprising liquid crystal polyester resin and fillers or other resins as needed, by conventionally known molding methods. Examples of molding methods include melt spinning, solution spinning, injection molding, compression molding, injection compression molding, calendering, stamping, etc.

[0125] (Electrical and electronic components)

[0126] Electrical and electronic components based on the present invention include molded articles (e.g., fibrous molded articles or injection molded articles) comprising liquid crystal polyester resin. Examples of electrical and electronic components including said molded articles include: antennas used in electronic or communication devices such as electronic toll collection (ETC), global positioning system (GPS), wireless area network (LAN) and mobile phones; high-speed transmission connectors; central processing unit (CPU) sockets; circuit boards; flexible printed circuit boards (FPC); circuit boards for stacking; millimeter-wave radar and quasi-millimeter-wave radar such as anti-collision radar; radio frequency identification (RFID) tags; capacitors; inverter parts; cable sheathing materials; insulating materials for secondary batteries such as lithium-ion batteries; speaker diaphragms, etc.

[0127] Example

[0128] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the embodiments.

[0129] <Example 1 of manufacturing liquid crystal polyester resin>

[0130] (Example 1-1)

[0131] In a polymerization vessel equipped with stirring blades, 25 mol% of p-hydroxybenzoic acid (HBA), 73 mol% of 6-hydroxy-2-naphthoic acid (HNA), and 2 mol% of m-hydroxybenzoic acid (mHBA) were added. Then, 0.50 mol% of terephthalic acid (TPA) was added relative to the total amount of these hydroxycarboxylic acids (100 mol%). Potassium acetate was added as a catalyst, and the polymerization vessel was subjected to three cycles of vacuum-nitrogen injection. Acetic anhydride (1.05 mol equivalent relative to the hydroxyl groups present in the system) was then added, and the temperature was raised to 150 °C. The acetylation reaction was carried out under reflux for 1.5 hours.

[0132] After acetylation, the polymerization vessel in the acetic acid distillation state was heated at 0.6°C / min until the temperature of the melt zone in the tank reached 313°C. Then, at the point when the amount of acetic acid distilled as a byproduct, indicating the degree of ester bond formation, reached 97% by mass relative to the theoretical total distillation, the polymer was extracted and cooled for solidification. The obtained polymer was pulverized to a size that could pass through a 2.0 mm mesh sieve. Next, the obtained polymer was heated from room temperature to 250°C using an inert oven (trade name: DN411I) manufactured by Yamato Scientific (stock), with nitrogen gas introduced at a flow rate of 30 L / min or higher, and solid-state polymerization was carried out at 250°C for 5 hours. Furthermore, the "250-5 h" solid-state polymerization conditions described in Table 1 indicate solid-state polymerization carried out at 250°C for 5 hours. Additionally, temperature switching between stages of solid-state polymerization was performed as quickly as possible within the capabilities of the equipment.

[0133] Subsequently, the polymer is allowed to dissipate heat naturally at room temperature to obtain the polyester resin of the present invention. In the case of a microscope heating stage (trade name: 10083L) manufactured by Japan High-Tech (Group) Co., Ltd., and a polarizing microscope (trade name: DS-Ri2) manufactured by Nikon (Group) Co., Ltd., the polyester resin is heated and melted on the microscope heating stage, and the liquid crystal properties are confirmed based on the presence or absence of optical anisotropy.

[0134] (Examples 1-2)

[0135] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Examples 1-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 260°C and held for 3 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0136] (Examples 1-3)

[0137] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Examples 1-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 270°C and held for 3 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0138] (Examples 1-4)

[0139] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Examples 1-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 280°C and held for 3 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0140] (Examples 1-5)

[0141] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Examples 1-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 290°C and held for 3 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0142] (Example 2-1)

[0143] The amount of mHBA added was changed to 1 mol%, and the polyester resin was obtained in the same manner as in Example 1-1. Next, the liquid crystallization property of the polyester resin was confirmed in the same manner as above.

[0144] (Example 2-2)

[0145] The amount of mHBA added was changed to 1 mol%, and the polyester resin was obtained in the same manner as in Examples 1-2. Next, the liquid crystallization property of the polyester resin was confirmed in the same manner as above.

[0146] (Examples 2-3)

[0147] The amount of mHBA added was changed to 1 mol%, and the polyester resin was obtained in the same manner as in Examples 1-3. Next, the liquid crystallization property of the polyester resin was confirmed in the same manner as above.

[0148] (Examples 2-4)

[0149] The amount of mHBA added was changed to 1 mol%, and the polyester resin was obtained in the same manner as in Examples 1-4. Next, the liquid crystallization of the polyester resin was confirmed in the same manner as above.

[0150] (Examples 2-5)

[0151] The amount of mHBA added was changed to 1 mol%, and the polyester resin was obtained in the same manner as in Examples 1-5. Next, the liquid crystallization of the polyester resin was confirmed in the same manner as above.

[0152] (Comparative Example 1-1)

[0153] Without adding TPA, the polyester resin was obtained in the same manner as in Examples 1-1. Next, the liquid crystal properties of the polyester resin were confirmed in the same way as above.

[0154] (Comparative Examples 1-2)

[0155] Without adding TPA, the polyester resin was obtained in the same manner as in Examples 1-2. Next, the liquid crystal properties of the polyester resin were confirmed in the same way as above.

[0156] (Comparative Examples 1-3)

[0157] Without adding TPA, the polyester resin was obtained in the same manner as in Examples 1-3. Next, the liquid crystal properties of the polyester resin were confirmed in the same way as above.

[0158] (Comparative Example 2-1)

[0159] Without adding TPA, but with the addition of 1 mol% of 4,4'-dihydroxybiphenyl (BP), the polyester resin was obtained in the same manner as in Examples 1-1. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0160] (Comparative Example 2-2)

[0161] Without adding TPA, but with the addition of 1 mol% of 4,4'-dihydroxybiphenyl (BP), the polyester resin was obtained in the same manner as in Examples 1-2. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0162] (Comparative Examples 2-3)

[0163] Without adding TPA, but with the addition of 1 mol% of 4,4'-dihydroxybiphenyl (BP), the polyester resin was obtained in the same manner as in Examples 1-3. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0164] (Comparative Examples 2-4)

[0165] Without adding TPA, but with the addition of 1 mol% of 4,4'-dihydroxybiphenyl (BP), the polyester resin was obtained in the same manner as in Examples 1-4. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0166] (Comparative Examples 2-5)

[0167] Without adding TPA, but with the addition of 1 mol% of 4,4'-dihydroxybiphenyl (BP), the polyester resin was obtained in the same manner as in Examples 1-5. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0168] (Comparative Example 3-1)

[0169] Without adding TPA, but with the addition of 1 mol% hydroquinone (HQ), the polyester resin was obtained in the same manner as in Examples 1-1. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0170] (Comparative Example 3-2)

[0171] Without adding TPA, but with the addition of 1 mol% hydroquinone (HQ), the polyester resin was obtained in the same manner as in Examples 1-2. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0172] (Comparative Example 3-3)

[0173] Without adding TPA, but with the addition of 1 mol% hydroquinone (HQ), the polyester resin was obtained in the same manner as in Examples 1-3. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0174] (Comparative Examples 3-4)

[0175] Without adding TPA, but with the addition of 1 mol% hydroquinone (HQ), the polyester resin was obtained in the same manner as in Examples 1-4. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0176] (Comparative Examples 3-5)

[0177] Without adding TPA, but with the addition of 1 mol% hydroquinone (HQ), the polyester resin was obtained in the same manner as in Examples 1-5. Next, the liquid crystallization properties of the polyester resin were confirmed as described above.

[0178] The composition ratio (mol%) of the constituent units and polymerization conditions of the polyester resins manufactured in the embodiments and comparative examples are shown in Table 1.

[0179] <Performance Evaluation of Liquid Crystal Polyester Resin 1>

[0180] <Determination of Melting Point>

[0181] The melting points of the liquid crystal polyester resins obtained in the examples and comparative examples were determined using a differential scanning calorimeter (DSC) manufactured by Hitachi High-Tech Science (Co., Ltd.). First, according to JIS-7121, the liquid crystal polyester resin was heated from room temperature to 360°C at a rate of 10°C / min to completely melt it. Then, it was cooled to 30°C at a rate of 10°C / min, and the peak of the resulting heating peak was designated as the crystallization point (Tc). Next, the temperature was increased to 360°C at a rate of 10°C / min, and the peak of the resulting endothermic peak was designated as the melting point (Tm). The melting points (Tm) are shown in Table 1.

[0182] <Determination of Melt Viscosity>

[0183] The melt viscosity (Pa·s) of the liquid crystal polyester resins obtained in the Examples and Comparative Examples was measured at 330°C and a shear rate of 100 / s using a capillary rheometer viscometer (Capilograph 1D, Toyo Seiki Co., Ltd.) and a capillary with an inner diameter of 1 mm and a length of 40 mm, according to JIS K7199. The measurement results are shown in Table 1.

[0184] <Determination of Mass Reduction Rate>

[0185] For the liquid crystal polyester resins obtained in the examples and comparative examples, the mass reduction rate was measured using a thermogravimetric analyzer (TGA) manufactured by Hitachi High-Tech Science (Co.), with nitrogen gas introduced at a flow rate of 300 mL / min or higher, from room temperature (30°C) to 370°C at a rate of 10°C / min, and held at 370°C for 30 minutes under the following two conditions. The measurement results are shown in Table 1.

[0186] (Condition 1)

[0187] • Initial mass loss rate: The final mass change (%) is measured from the start of heating at room temperature (20°C) to the point of holding at 370°C for 30 minutes. Since the mass of gases, etc., evaporates at low temperatures, it is an indicator of thermal stability from the initial state.

[0188] (Condition 2)

[0189] • Mass reduction rate during holding at 370℃: The final mass change (%) is measured after holding at 370℃ for 30 minutes. This is an indicator for evaluating stability during melting.

[0190] [Table 1]

[0191]

[0192] As clearly demonstrated by the results in Table 1, the mass reduction of the liquid crystal polyester resin by adding a small amount of dicarboxylic acid to the aromatic hydroxycarboxylic acid is less compared to adding a small amount of diol. The decrease in initial mass reduction rate refers to the reduction of gases or sublimations in the liquid crystal polyester, including those produced during residual heat processing. The decrease in mass reduction rate during 370°C holding indicates suppression of decomposition or degradation during melting, or inhibition of polymerization reactions during melting. This refers to the reduction of foreign matter generation or surface expansion (blistering) during melt forming and post-forming heat treatment of the obtained liquid crystal polyester, as well as the reduction of melt viscosity fluctuations caused by changes in the polymerization state during melt processing. The addition of dicarboxylic acid improves stability from any of these perspectives.

[0193] In addition, Figure 1 The graphs show the relationship between melt viscosity and final solid-state polymerization temperature in the series of Examples 2 and Comparative Examples 1 to 3.

[0194] exist Figure 2 The graphs show the relationship between melting point and final temperature of solid-state polymerization in the series of Examples 2 and Comparative Examples 1 to 3.

[0195] exist Figure 3 The graphs show the relationship between melt viscosity and melting point in the series of Examples 2 and Comparative Examples 1 to 3.

[0196] exist Figure 4 The graphs show the relationship between melt viscosity and final solid-state polymerization temperature in the series of Examples 1, 2, and 1 (Comparative Example 1).

[0197] exist Figure 5 The graphs show the relationship between melting point and final temperature of solid-state polymerization in the series of Examples 1, 2, and 1 (Comparative Example 1).

[0198] exist Figure 6 The graphs show the relationship between melt viscosity and melting point in the series of Examples 1, Examples 2, and Comparative Examples 1.

[0199] like Figures 1-3 As shown, in the Example 2 series with a small amount of dicarboxylic acid added, compared with the Comparative Example 1 series without dicarboxylic acid added, and the Comparative Example 2 and Comparative Example 3 series with a small amount of diol added, the elongation at the final temperature of solid-state polymerization was reliably increased, and the increase in melt viscosity was suppressed. Furthermore, it was confirmed that the melting point obtained at this specific viscosity exceeded 300°C, demonstrating sufficiently good heat resistance.

[0200] like Figures 4-6 As shown, by adjusting the amount of dicarboxylic acid added, even when increasing the final temperature of solid-state polymerization, the property of reliably elongating the melt viscosity while suppressing the degree of increase in melt viscosity can be maintained, and the degree of increase can be controlled. This indicates that by designing the constituent unit (II) introduced into the system within an appropriate range, the progress of solid-state polymerization can be controlled while maintaining a preferred high melting point.

[0201] <Performance Evaluation of Liquid Crystal Polyester Resin 2>

[0202] <Preparation of Bending Test Pieces>

[0203] Solid-state polymerization was carried out, and the liquid crystal polyester resins obtained in Examples 1-3, 2-5 and Comparative Example 1-1 with the same melt viscosity, i.e. the same degree of polymerization, were heated and melted at a melting point of +20°C and injection molded (mold temperature 80°C) to produce bending test pieces of 80 mm × 12.5 mm × 2 mm (thickness).

[0204] <Determination of Load-Deflection Temperature (DTUL)>

[0205] Using the prepared bending test specimens, a load of 0.45 MPa was applied along the ply direction (to a 12.5 mm × 2 mm surface) according to ASTM D648, and the load-bearing flexural temperature (DTUL) was determined. The average values ​​measured with N=3 are shown in Table 2. A higher load-bearing flexural temperature indicates better practical heat resistance.

[0206] [Table 2]

[0207]

[0208] As shown in Table 1, a decrease in melting point was observed in Examples 1-3 compared to Examples 2-5 and Comparative Example 1-1. However, as clarified according to Table 2, the load flexural temperature, which indicates the heat resistance of the injection-molded component, was at the same level in Examples 1-3 and Examples 2-5 compared to Comparative Example 1-1. That is, the decrease in melting point observed in DSC was independent of the practical heat resistance of the component observed in the load flexural temperature. This indicates that the group of examples has high practical heat resistance for the component, and at the same time, molding can be performed at a lower temperature, i.e., with less energy, compared to the group of comparative examples. In addition, as shown in Table 1, the initial mass reduction rate and the mass reduction rate during 370°C maintenance decreased in the order of Comparative Example 1-1, Examples 1-3, and Examples 2-5, indicating improved thermal stability. This indicates that by adjusting the solid-phase polymerization progress during manufacturing and extending the time to reach a specific melt viscosity state, components that deteriorate thermal stability, such as polymerization byproducts or low molecular weight components of the liquid crystal polyester resin, can be fully discharged, thereby improving thermal stability.

[0209] <Example 2 of manufacturing liquid crystal polyester resin>

[0210] (Examples 1-6)

[0211] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Examples 1-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 270°C and held for 1.5 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0212] (Examples 2-6)

[0213] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Example 2-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 290°C and held for 1.5 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0214] (Comparative Examples 1-4)

[0215] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Comparative Example 1-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 4 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0216] (Comparative Examples 2-6)

[0217] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Comparative Example 2-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 2 hours, then raised to 280°C and held for 2 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0218] (Comparative Examples 3-6)

[0219] The solid-state polymerization conditions were modified as described below, and the polyester resin was obtained in the same manner as in Example 3-1. In the solid-state polymerization, the temperature was raised from room temperature to 250°C and held for 4.5 hours. Next, the liquid crystal properties of the polyester resin were confirmed as described above.

[0220] The composition ratio (mol%) of the constituent units and polymerization conditions of the polyester resins manufactured in the embodiments and comparative examples are shown in Table 3.

[0221] In addition, the melting point, melt viscosity, and mass loss rate of the liquid crystal polyester resins obtained in the examples and comparative examples were measured in the same manner as in <Performance Evaluation of Liquid Crystal Polyester Resins 1>. The measurement results are shown in Table 3.

[0222] [Table 3]

[0223]

[0224] Table 3 summarizes the physical properties of liquid crystal polyesters polymerized by adjusting the solid-state polymerization progress through changes in the constituent units, with melt viscosity approximately reaching 100 Pa·s. As is evident from Table 3, the mass reduction of the liquid crystal polyester resin by adding a small amount of dicarboxylic acid to the aromatic hydroxycarboxylic acid is less than that by adding a small amount of diol. The decrease in initial mass reduction rate refers to the reduction of gases or sublimations in the liquid crystal polyester, including those produced during residual heat processing. The decrease in mass reduction rate during 370°C holding indicates the suppression of decomposition or deterioration during melting, or the inhibition of polymerization reactions during melting. This refers to the reduction of foreign matter generation or surface expansion (bubbling) during melt forming and post-forming heat processing of the obtained liquid crystal polyester, as well as the reduction of melt viscosity fluctuations caused by changes in the polymerization state during melt processing. The addition of dicarboxylic acid improves stability from any of these perspectives. On the other hand, the addition of a small amount of diol, similar to the addition of a small amount of dicarboxylic acid, can inhibit the progress of solid-state polymerization, but no improvement is seen in the initial mass reduction rate and the mass reduction rate during the maintenance at 370°C as when a small amount of dicarboxylic acid is added.

[0225] <Performance Evaluation of Liquid Crystal Polyester Resin 3>

[0226] <Amount of Escaped Gases Generated>

[0227] Using a headspace sampler (Agilent Technologies 7697A), 3 g of each powder sample of the liquid crystal polyester resin obtained in Examples 1-3, 1-4, 2-6, and Comparative Examples 1-4, 2-3, and 3-1 were heated at 190°C for 1 hour, during which time the compounds contained in the sample vaporization chamber vaporized. The vaporized component generated at this time was referred to as the escape gas, and it was received by a gas chromatograph body (Agilent Technologies 7820A) heated to 45°C, with a standby time of 3 minutes. The vaporized analyte component was transported to the column by a mobile phase called the carrier gas flowing within the gas chromatograph. Subsequently, the escape gas transported to the column was quantified by increasing the temperature from room temperature to 280°C at a rate of 20°C / min. The determination results (mass ratio of escape gas generated from the powder used in the determination) are shown in Table 4. The less gas is generated, the more it can suppress the generation of bubbles (surface expansion) during molding, as well as the poor appearance or decreased physical properties of the molded product.

[0228] [Table 4]

[0229]

[0230] As clearly demonstrated by the results in Table 4, the amount of gas emitted from the liquid crystal polyester resin can be suppressed by adding a small amount of dicarboxylic acid to the aromatic hydroxycarboxylic acid. On the other hand, no effect on reducing gas emission could be confirmed when a small amount of diol was added. This is believed to be due to the following difference in properties: when a small amount of diol is added, the polymer chain ends have high reactivity and react to become acetyl groups that produce acetic acid, but when a small amount of dicarboxylic acid is added, the reactivity is low and no acetic acid gas is produced.

[0231] <Performance Evaluation of Liquid Crystal Polyester Resin 4>

[0232] <Changes in hue>

[0233] For each powder sample of the liquid crystal polyester resin obtained in Examples 2-6 and Comparative Examples 1-4, 2-3, and 3-1, a spectrophotometer (Konica Minolta, CM-600d) was used. After calibration using a white calibration plate, the L... a b Color rendering system (International Commission on Illumination (CIE) 1976) L a b The values ​​of each hue were measured. Each measurement was performed three times, and the average value was taken as the measured value. ΔE was calculated based on the measured values ​​using a color difference formula, and is shown in Table 5. It can be said that the smaller the hue change value (ΔE), the closer it is to white, and the better.

[0234] [Table 5]

[0235]

[0236] As shown in Table 5, with the addition of a small amount of dicarboxylic acid, ΔE is small, falling within the same hue range as Comparative Example 4-1, which is the baseline containing only hydroxycarboxylic acid. On the other hand, with the addition of a small amount of diol, ΔE increases predominantly, and a significant deterioration in color is confirmed compared to the one containing hydroxycarboxylic acid. Therefore, the addition of a small amount of dicarboxylic acid, compared to the addition of a small amount of diol, shows an effect that does not deteriorate the hue of the liquid crystal polyester.

[0237] <Performance Evaluation of Liquid Crystal Polyester Resin 5>

[0238] <Preparation of Flat Plate Test Slides>

[0239] The liquid crystal polyester resins obtained in Examples 1-6, Examples 2-6, Comparative Examples 2-6, and Comparative Examples 3-6 were heated and melted at a melting point of +20°C (mold temperature 80°C) and injection molded to produce flat test pieces with a thickness of 30 mm × 30 mm × 0.4 mm.

[0240] <Dielectric Loss Tangent Measurement (10 GHz)>

[0241] The dielectric loss tangent (tanδ) in the in-plane direction of the fabricated flat test piece was measured at a frequency of 10 GHz using a Keysight Technologies N5247A network analyzer at 23°C and 50% RH via the Split Pillar Dielectric Resonator (SPDR) method. The measurement and calculation results are shown in Table 6. A lower value for the product of the dielectric loss tangents indicates a reduction in the impact caused by dielectric loss.

[0242] [Table 6]

[0243]

[0244] As is evident from the results in Table 6, the liquid crystal polyester resins obtained in Examples 1-6 and Examples 2-6 have low dielectric loss tangents.

Claims

1. A liquid crystal polyester resin comprising only a constituent unit (I) derived from an aromatic hydroxycarboxylic acid and a constituent unit (II) derived from a dicarboxylic acid, obtained by solid-state polymerization, characterized in that: The composition ratio of the constituent unit (II) relative to the constituent unit (I) is more than 0 mol% and less than 2.0 mol%.

2. The liquid crystal polyester resin according to claim 1, wherein the constituent unit (I) comprises constituent units derived from three or more aromatic hydroxycarboxylic acids.

3. The liquid crystal polyester resin according to claim 1, wherein the constituent unit (I) comprises at least a constituent unit (A) derived from p-hydroxybenzoic acid and a constituent unit (B) derived from 6-hydroxy-2-naphthoic acid.

4. The liquid crystal polyester resin according to claim 3, wherein the constituent unit (I) has the highest composition ratio of the constituent unit (B).

5. The liquid crystal polyester resin according to claim 3, wherein the composition of the constituent unit (A) in the constituent unit (I) is more than that of the constituent unit (A).

6. The liquid crystal polyester resin according to claim 3, wherein the constituent unit (I) further comprises a constituent unit (C) derived from an aromatic hydroxycarboxylic acid other than the constituent unit (A) and the constituent unit (B). Relative to the entirety of the constituent unit (I) derived from aromatic hydroxycarboxylic acids, the compositional ratio (molar %) of the constituent units (A) to (C) satisfies the following condition: 15 mol% ≤ Constituent Unit (A) ≤ 30 mol% 60 mol% ≤ Constituent Unit (B) ≤ 80 mol% 0.1 mol% ≤ constitutive unit (C) ≤ 10 mol%.

7. The liquid crystal polyester resin according to claim 6, wherein the constituent unit (C) is a constituent unit derived from at least one selected from the group consisting of m-hydroxybenzoic acid, 6-hydroxynicotinic acid, and 4'-hydroxy-4-biphenylcarboxylic acid.

8. The liquid crystal polyester resin according to claim 1, wherein the constituent unit (II) is derived from an aromatic dicarboxylic acid.

9. The liquid crystal polyester resin according to claim 1, wherein the constituent unit (II) is derived from terephthalic acid.

10. The liquid crystalline polyester resin of claim 1, wherein the dielectric loss tangent at a measurement frequency of 10 GHz is 1.0 x 10 -3 The following.

11. The liquid crystal polyester resin according to claim 1, wherein the mass reduction after being held at 370°C under a nitrogen flow for 30 minutes is less than 0.60% by mass.

12. The liquid crystal polyester resin according to claim 1, wherein the melt viscosity at 100 / s from the melting point to melting point +30°C is 10 Pa·s or higher.

13. A fibrous molded article comprising the liquid crystal polyester resin as described in any one of claims 1 to 12.

14. A sheet-like molded article comprising the liquid crystal polyester resin as described in any one of claims 1 to 12.

15. An injection-molded article comprising the liquid crystal polyester resin as claimed in any one of claims 1 to 12.

16. An electrical and electronic component comprising the molded article as described in claim 13.

17. An electrical and electronic component comprising the molded article as described in claim 14.

18. An electrical and electronic component comprising the molded article as described in claim 15.

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