Liquid crystal polyester resin, liquid crystal polyester resin composition and molded articles thereof

Abstract

The liquid crystal polyester resin of this invention comprises building units derived from aromatic hydroxycarboxylic acids, aromatic diols, and aromatic dicarboxylic acids. The content of building units derived from aromatic hydroxycarboxylic acids is 15-80 mol% relative to 100 mol% of all building units in the liquid crystal polyester resin, the content of building units derived from aromatic diols is 2-40 mol%, and the content of building units derived from aromatic dicarboxylic acids is 2-40 mol%. Furthermore, the temperature sensitivity coefficient and curing initiation temperature obtained from rheometer spectroscopy are within a certain range. This invention provides a liquid crystal polyester resin that can be molded at a wide range of molding temperatures, exhibits excellent molding stability, and has low thickness dependence on flowability.

Description

Technical Field

[0001] The present invention relates to a liquid crystal polyester resin, a liquid crystal polyester resin composition and a molded product composed thereof. Prior Art

[0002] Liquid crystal polyester resins, due to their excellent heat resistance, fluidity, and dimensional stability, are used in electrical and electronic components requiring these properties. In recent years, the miniaturization of smartphones and other devices has further increased demand for higher component density, thinner walls, and smaller cross-sections. For example, proposals include liquid crystal polyester resins containing structural units derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, and terephthalic acid (e.g., Patent Documents 1-4); liquid crystal polyester resins containing structural units derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, terephthalic acid, and isophthalic acid (e.g., Patent Document 5); and liquid crystal polyester resins containing structural units derived from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, hydroquinone, terephthalic acid, and isophthalic acid (e.g., Patent Document 6). These resins combine excellent fluidity with high strength and blister resistance. Furthermore, it has been proposed to achieve both rigidity and retention stability by using a liquid crystal polyester resin containing structural units derived from p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, terephthalic acid, and isophthalic acid (for example, Patent Documents 7 and 8). [Prior Art Literature] [Patent Document]

[0003] Patent Document 1: Japanese Patent Application Publication No. 2021-24985 Patent Document 2: Japanese Patent Application Publication No. 2017-137438 Patent Document 3: International Publication No. 2018 / 101214 Patent Document 4: Japanese Patent Application Laid-Open No. 2012-126842 Patent Document 5: International Publication No. 2012 / 137636 Patent Document 6: International Publication No. 2013 / 51346 Patent Document 7: Japanese Patent Publication No. 2016-523291 Patent Document 8: Japanese Patent Application Laid-Open No. 2004-256656 Summary of the Invention

[0004] (Problems that the invention aims to solve)

[0005] However, when molding temperatures are high, resins with excellent fluidity can produce drooling (a phenomenon in which uncured resin leaks out of the nozzle tip and dangles during molding) or stringing (a phenomenon in which uncured resin extends linearly from the gate apex when the mold is opened), or generate gas during molding, reducing productivity and lowering the quality of the molded product. To prevent these problems, the molding temperature can be lowered. However, the techniques described in Patent Documents 1-8 suffer from the following issues: excessively lowering the molding temperature can partially solidify the resin, leading to fluidity variations and a narrowing of the molding temperature range. Furthermore, because fluidity is highly dependent on thickness, fluidity variations are more likely to occur when molding products with varying thicknesses. Furthermore, injection molding involves repeated shutdowns and resets of the molding machine for product switching and molding failures. Therefore, it is crucial to shorten the time required to obtain a good product after reset and improve molding stability. The methods described in Patent Documents 1-8 also suffer from molding stability issues.

[0006] The present invention aims to provide a liquid crystal polyester resin, a liquid crystal polyester resin composition, and a molded product composed thereof, which can be molded at a wide range of molding temperatures, has excellent molding stability, and has low thickness dependence of fluidity. (Technical means to solve the problem)

[0007] The present inventors have conducted intensive research to address the above-mentioned issues and have discovered a liquid crystal polyester resin comprising 15 to 80 mol% of structural units derived from an aromatic hydroxycarboxylic acid, 2 to 40 mol% of structural units derived from an aromatic diol, and 2 to 40 mol% of structural units derived from an aromatic dicarboxylic acid, relative to 100 mol% of all structural units in the liquid crystal polyester resin. The liquid crystal polyester resin, having a controlled temperature sensitivity coefficient and a controlled curing onset temperature, can be molded over a wide range of molding temperatures, exhibits excellent molding stability, and exhibits low thickness dependence of fluidity, thereby completing the present invention.

[0008] That is, the present invention is as follows: (1) A liquid crystal polyester resin comprising structural units derived from an aromatic hydroxycarboxylic acid, structural units derived from an aromatic diol, and structural units derived from an aromatic dicarboxylic acid, wherein, relative to 100 mol% of all structural units of the liquid crystal polyester resin, the content of structural units derived from the aromatic hydroxycarboxylic acid is 15 to 80 mol%, the content of structural units derived from the aromatic diol is 2 to 40 mol%, and the content of structural units derived from the aromatic dicarboxylic acid is 2 to 40 mol%, and the following requirement (α) is satisfied: (α): The temperature sensitivity coefficient measured by the following method is less than 0.020, and B(x) is between -35 and -15°C; When the melting point of the liquid crystal polyester resin is set to Tm (°C), the liquid crystal polyester resin is measured using a rheometer in the following manner. In the rheometer spectrum curve of the liquid crystal polyester resin obtained by setting the x-axis to ΔT (°C) = measurement temperature - Tm (°C) and the y-axis to the logarithm of the complex viscosity (log (η (Pa·s))), the point where ΔT = 20°C is set as point A, the point where ΔT = 10°C is set as point A', the point below the melting point and with a complex viscosity η of 10000 Pa·s is set as point C, and the point where the complex viscosity η is 5000 Pa·s is set as point C. When the point where the temperature reaches zero Pa·s is defined as point C', the line passing through points A and A' is defined as line t, the line passing through points C and C' is defined as line u, the intersection of line t and line u is defined as point B', the line passing through point B' and parallel to the y-axis is defined as line v, and the intersection of line v and the rheometer spectrum curve is defined as point B. The absolute value of the slope of the line w connecting points A and B is defined as the temperature sensitivity coefficient, and the ΔT value at point B is defined as B(x); The above rheometer spectrum curve was obtained in the rheometer vibration measurement mode with a parallel plate gap of 1 mm, a strain of 10%, and a frequency of 1 Hz. After maintaining the temperature at Tm + 30°C for 5 minutes, the temperature was cooled at a rate of 0.17°C / s to a temperature where the complex viscosity reached 50,000 (Pa·s). The melting point Tm of the liquid crystal polyester resin is the endothermic peak temperature Tm1 observed when the liquid crystal polyester resin is heated from room temperature at a heating rate of 20°C / minute in differential calorimetry, maintained at Tm1 + 20°C for 5 minutes, then temporarily cooled to room temperature at a cooling rate of 20°C / minute, and then heated again at a heating rate of 20°C / minute. (2) The liquid crystal polyester resin of (1), comprising a structural unit selected from the following structural units (I) to (V) and satisfying the following requirements (a) to (d): 25≦[I]≦75 …(a) 1≦[II]≦20 …(b) 2≦[III]+[IV]≦35 …(c) 2≦[V]≦35 …(d) [I] to [V] represent the content (mol %) of each of the following structural units (I) to (V) relative to 100 mol % of all structural units of the liquid crystal polyester resin.

[0009] [Chemistry 1]

[0010] (3) The liquid crystal polyester resin of (1) or (2), which comprises the following structural units (II) and (VI) and satisfies the following requirements (e) and (f): 0.01≦[Ⅵ]≦10 …(e) [VI] / [II]<1 …(f) [II] and [VI] represent the content (mol %) of each of the following structural units (II) and (VI) relative to 100 mol % of all structural units of the liquid crystal polyester resin.

[0011] [Chemistry 2]

[0012] (4) The liquid crystal polyester resin according to any one of (1) to (3), comprising a structural unit selected from the following structural units (I) to (VI) and satisfying the following requirements (g) to (l): 25≦[I]≦75 …(g) 1≦[II]≦20 …(h) 2≦[III]+[IV]≦35…(i) 2≦[V]≦35 …(j) 0.01≦[VI]≦10 …(k) [VI] / [II]<1 …(l) [I] to [VI] represent the content (mol %) of each of the following structural units (I) to (VI) relative to 100 mol % of all structural units of the liquid crystal polyester resin.

[0013] [Chemistry 3]

[0014] (5) The liquid crystal polyester resin according to any one of (1) to (4), further satisfying the following requirement (m): 0<[III] / [IV]<1.5 …(m) [III] and [IV] represent the content (mol %) of each of the aforementioned structural units (III) and (IV) relative to 100 mol % of all structural units of the liquid crystal polyester resin. (6) The liquid crystal polyester resin according to any one of (1) to (5), further satisfying the following requirement (n): 99≦[I]+[II]+[III]+[IV]+[V]+[VI]≦100…(n) [I] to [VI] represent the content (mol %) of each of the aforementioned structural units (I) to (VI) relative to 100 mol % of all structural units of the liquid crystal polyester resin. (7) A liquid crystal polyester resin composition comprising 10 to 200 parts by weight of a filler relative to 100 parts by weight of the liquid crystal polyester resin of any one of (1) to (6). (8) A molded article composed of the liquid crystal polyester resin of any one of (1) to (6) or the liquid crystal polyester resin of (7). (9) The molded product as described in (8), which is selected from any one of the group consisting of connectors, relays, switches, bobbins and actuator parts of camera modules. (Compared with the efficacy of previous technologies)

[0015] The liquid crystal polyester resin of the present invention can be molded over a wide range of molding temperatures, exhibits excellent molding stability, and exhibits minimal thickness dependence of fluidity. The liquid crystal polyester resin of the present invention is particularly suitable for molding small electrical and electronic components. Simple diagram description

[0016] FIG1 is a graph showing a rheometer spectrum curve illustrating the requirement (α) satisfied by the liquid crystal polyester resin of the present invention. FIG. 2 shows rheometer spectrum curves of the liquid crystal polyester resin of the present invention and the conventional one. FIG3 is a perspective view showing a connector molded product used for evaluation of molding stability. Implementation Method

[0017] Hereinafter, the present invention will be described in detail.

[0018] <Liquid Crystal Polyester Resin> Liquid crystal polyester resins are polyesters that form an anisotropic melt phase. Examples of such polyester resins include polyesters composed of structural units that form an anisotropic melt phase, such as oxycarbonyl units, dioxy units, and dicarbonyl units, as described below.

[0019] Next, the temperature sensitivity coefficient of the liquid crystal polyester resin obtained from the rheometer spectrum curve is described. The liquid crystal polyester resin of the present invention satisfies the following requirement (α): (α): The temperature sensitivity coefficient measured by the following method is less than 0.020, and B(x) is between -35 and -15°C; The calculation method for the temperature sensitivity coefficient and B(x) described above is explained with reference to Figure 1. When the melting point of the liquid crystal polyester resin is set to Tm (°C), the liquid crystal polyester resin is measured using a rheometer in the following manner, with the x-axis plotted as ΔT (°C) = measurement temperature - Tm (°C) and the y-axis plotted as the logarithm of the complex viscosity (log(η(Pa·s))). This yields the rheometer spectrum curve 1 of the liquid crystal polyester resin shown in Figure 1. In rheometer spectrum curve 1, the point at ΔT = 20°C is designated as point A, the point at ΔT = 10°C is designated as point A', the point below the melting point with a complex viscosity η of 10,000 Pa·s is designated as point C, and the point at a complex viscosity η of 5,000 Pa·s is designated as point C'. When the straight line passing through points A and A' is designated as line t, the straight line passing through points C and C' is designated as line u, the intersection of line t and line u is designated as point B', the straight line passing through point B' and parallel to the y-axis is designated as line v, and the intersection of line v and rheometer spectrum curve 1 is designated as point B, the absolute value of the slope of the straight line w connecting points A and B is defined as the temperature sensitivity coefficient, and the ΔT value at point B is defined as B(x).

[0020] The above rheometer spectrum curve was obtained in the rheometer's vibration measurement mode with a parallel plate gap of 1 mm, a strain of 10%, and a frequency of 1 Hz. After maintaining the temperature at Tm + 30°C for 5 minutes, the temperature was cooled at a rate of 0.17°C / second to a temperature at which the complex viscosity reached 50,000 (Pa·s).

[0021] The melting point Tm of the liquid crystal polyester resin is the endothermic peak temperature Tm1 observed when the liquid crystal polyester resin is heated from room temperature at a heating rate of 20°C / minute in differential calorimetry. The temperature is then maintained at Tm1 + 20°C for 5 minutes, then temporarily cooled to room temperature at a cooling rate of 20°C / minute, and then heated again at a heating rate of 20°C / minute.

[0022] Rheometry is a method for evaluating the rheological properties (flow characteristics), one of the most important properties of a resin. The temperature sensitivity coefficient (TSC) is obtained from the rheometer spectrum using the aforementioned method and is defined by the absolute value of the slope of the line w connecting points A and B. The TSC indicates how the dynamic viscosity (complex viscosity) of a liquid crystal polyester resin changes with temperature under shear conditions. The lower the TSC, the less susceptible the liquid crystal polyester resin's flow characteristics are to changes in response to external factors such as temperature or shear. The present invention has discovered that liquid crystal polyester resins with a TSC of 0.020 or less can be molded over a wide range of molding temperatures, exhibit excellent molding stability, and exhibit low thickness dependence of fluidity. If the TSC exceeds 0.020, controlling the liquid crystal polyester resin's behavior from melting to solidification becomes difficult, narrowing the molding temperature range and increasing the thickness dependence of fluidity. Furthermore, liquid crystal polyester resins with a temperature sensitivity coefficient exceeding 0.020 experience fluidity fluctuations due to slight temperature differences between various parts of the molding machine. This can lead to time consuming recovery from machine shutdown to achieving a good product, resulting in poor molding stability. Considering the moldable temperature range, molding stability, and the thickness dependence of fluidity, the temperature sensitivity coefficient is preferably 0.018 or less, and more preferably 0.016 or less. Furthermore, a lower temperature sensitivity coefficient is preferred, with a minimum value of 0 being considered.

[0023] Furthermore, the ΔT value B(x) at point B shown in the aforementioned requirement (α) of the liquid crystal polyester resin of the present invention is between -35°C and -15°C. B(x) is the temperature at which the liquid crystal polyester resin begins to cure under shear conditions (hereinafter, B(x) may be referred to as the curing onset temperature). If B(x) is lower than -35°C, burrs during molding and flow from the nozzle tip become problems, narrowing the temperature range for molding. Furthermore, if B(x) exceeds -15°C, it becomes difficult to control the curing behavior of the liquid crystal polyester resin, narrowing the temperature range for molding, deteriorating molding stability, and increasing the thickness dependence of fluidity. B(x) is preferably -30°C or higher, more preferably -28°C or higher. Furthermore, B(x) is preferably -16°C or lower, more preferably -18°C or lower, and even more preferably -20°C or lower.

[0024] Figure 2 shows an example of a rheometer spectrum curve (S1) for the liquid crystal polyester resin of the present invention and an example of a rheometer spectrum curve (S2) for a conventional liquid crystal polyester resin. Also shown are the straight lines L1 and L2, respectively, representing the temperature sensitivity coefficients defined above. As shown in Figure 2 , the absolute value of the slope of L1 is smaller than that of L2, indicating that the temperature sensitivity coefficient of the liquid crystal polyester resin of the present invention is smaller than that of the conventional liquid crystal polyester resin.

[0025] Comparing the spectral curves of S1 and S2 in Figure 2 shows that S1 exhibits suppressed viscosity changes above the curing onset temperature B(x). As the temperature decreases, the viscosity increases sharply from near the curing onset temperature. The liquid crystal polyester resin of the present invention exhibiting viscosity change behavior similar to S1 can be molded over a wide range of molding temperatures, while also exhibiting excellent molding stability and low thickness dependence of fluidity. The value that quantitatively indicates that the rheometer spectral curve and S1 have the same shape is the temperature sensitivity coefficient defined above.

[0026] Methods for controlling the aforementioned temperature sensitivity coefficient and curing onset temperature within preferred ranges include, for example, setting the structural units constituting the liquid crystal polyester resin within the preferred ranges described below, and / or setting the liquid crystal polyester resin production method to the preferred method described below. Details are described in the sections "Structural Units Constituting the Liquid Crystalline Polyester Resin" and "Method for Producing the Liquid Crystalline Polyester Resin" below.

[0027] Next, the structural units constituting the liquid crystal polyester resin are described.

[0028] The liquid crystal polyester resin of the present invention comprises a structural unit derived from an aromatic hydroxycarboxylic acid, a structural unit derived from an aromatic diol, and a structural unit derived from an aromatic dicarboxylic acid.

[0029] The liquid crystal polyester resin of the present invention includes, as oxycarbonyl units, 15 to 80 mol% of aromatic hydroxycarboxylic acid-derived structural units relative to 100 mol% of all structural units in the liquid crystal polyester resin. If the content of aromatic hydroxycarboxylic acid-derived structural units is less than 15%, liquid crystallinity is impaired, narrowing the temperature range for molding. The content is preferably 20 mol% or greater, more preferably 25 mol% or greater. On the other hand, if the content exceeds 80 mol%, control of the crystallinity and melting point of the liquid crystal polyester resin becomes difficult, narrowing the temperature range for molding. The content is preferably 75 mol% or less, more preferably 70 mol% or less. Specific examples of aromatic hydroxycarboxylic acid-derived structural units include those derived from p-hydroxybenzoic acid, m-hydroxybenzoic acid, and 6-hydroxy-2-naphthoic acid.

[0030] The liquid crystal polyester resin of the present invention includes, as dioxy units, 2 to 40 mol% of aromatic diol-derived structural units relative to 100 mol% of all structural units in the liquid crystal polyester resin. If the content of aromatic diol-derived structural units is less than 2 mol%, it is difficult to control the crystallinity and melting point of the liquid crystal polyester resin, and the molding temperature range is narrowed. The content is preferably 7 mol% or greater, more preferably 10 mol% or greater. On the other hand, if the content exceeds 40 mol%, liquid crystallinity is impaired, and the molding temperature range is narrowed. The content is preferably 37 mol% or less, more preferably 35 mol% or less. Examples of structural units derived from aromatic diols include those derived from 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, tert-butylhydroquinone, phenylhydroquinone, chlorohydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfide, and 4,4'-dihydroxybenzophenone. From the perspectives of excellent availability and a wide range of molding temperatures, structural units derived from 4,4'-dihydroxybiphenyl or hydroquinone are preferably used.

[0031] The liquid crystal polyester resin of the present invention includes 2 to 40 mol% of structural units derived from aromatic dicarboxylic acids as dicarbonyl units, relative to 100 mol% of all structural units in the liquid crystal polyester resin. If the content of structural units derived from aromatic carbonyl groups is less than 2 mol%, it is difficult to control the crystallinity and melting point of the liquid crystal polyester resin, and the molding temperature range is narrowed. The content is preferably 7 mol% or greater, more preferably 10 mol% or greater. On the other hand, if the content exceeds 40 mol%, liquid crystallinity is impaired, thereby narrowing the molding temperature range. The content is preferably 37 mol% or less, more preferably 35 mol% or less. Examples of structural units derived from aromatic dicarboxylic acids include those derived from terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 3,3'-diphenyl dicarboxylic acid, 2,2'-diphenyl dicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, and 4,4'-diphenyl ether dicarboxylic acid. From the perspective of excellent availability and a wide range of molding temperatures, structural units derived from terephthalic acid or isophthalic acid are preferably included.

[0032] Next, the structural units that comprise the liquid crystal polyester resin will be described in more detail. The liquid crystal polyester resin of the present invention preferably comprises structural units selected from the following structural units (I) to (V) and satisfies the following requirements (a) to (d), from the perspectives of being moldable over a wide range of molding temperatures, exhibiting excellent molding stability, and exhibiting minimal thickness dependence of fluidity. 25≦[I]≦75 …(a) 1≦[II]≦20 …(b) 2≦[III]+[IV]≦35 …(c) 2≦[V]≦35 …(d) [I] to [V] represent the content (in mol %) of each structural unit (I) to (V) relative to 100 mol % of all structural units of the liquid crystal polyester resin.

[0033] [Chemistry 4]

[0034] The liquid crystal polyester resin of the present invention preferably contains 25 mol% or more of the structural unit (I) as an oxycarbonyl unit, relative to 100 mol% of all structural units in the liquid crystal polyester resin. Structural unit (I) is a structural unit derived from p-hydroxybenzoic acid. From the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of structural unit (I) is more preferably 35 mol% or more, and even more preferably 45 mol% or more.

[0035] On the other hand, the liquid crystal polyester resin of the present invention preferably contains 75 mol% or less of the structural unit (I) relative to 100 mol% of all structural units in the liquid crystal polyester resin. From the perspectives of being moldable over a wide range of molding temperatures, exhibiting excellent molding stability, and having low thickness dependence of fluidity, the content of the structural unit (I) is preferably 65 mol% or less, more preferably 55 mol% or less.

[0036] The liquid crystal polyester resin of the present invention preferably contains 1 mol% or more of structural unit (II) as an oxycarbonyl unit, relative to 100 mol% of all structural units in the liquid crystal polyester resin. Structural unit (II) is derived from 6-hydroxy-2-naphthoic acid. From the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of structural unit (II) is preferably 2 mol% or more, more preferably 3 mol% or more.

[0037] On the other hand, the liquid crystal polyester resin of the present invention preferably contains 20 mol% or less of the structural unit (II) relative to 100 mol% of all structural units in the liquid crystal polyester resin. From the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of the structural unit (II) is preferably 15 mol% or less, more preferably 10 mol% or less.

[0038] The liquid crystal polyester resin of the present invention preferably has a molar ratio ([I] / [II]) of 3 or more, more preferably 5 or more, and even more preferably 7 or more, of the contents of structural units (I) and (II) from the viewpoints of being moldable over a wide range of molding temperatures, having excellent molding stability, and having low thickness dependence of fluidity. On the other hand, from the viewpoints of being moldable over a wide range of molding temperatures and having low thickness dependence of fluidity, [I] / [II] is preferably 20 or less, more preferably 18 or less, and even more preferably 16 or less.

[0039] Furthermore, as the oxycarbonyl unit, a structural unit derived from m-hydroxybenzoic acid or the like can be used within a range not impairing the effects of the present invention.

[0040] The liquid crystal polyester resin of the present invention preferably contains structural unit (III) as a dioxy unit. Structural unit (III) is a structural unit derived from 4,4'-dihydroxybiphenyl. To ensure molding over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of structural unit (III) is preferably 1 mol% or greater, more preferably 3 mol% or greater, and even more preferably 5 mol% or greater, relative to 100 mol% of all structural units in the liquid crystal polyester resin. On the other hand, to ensure molding over a wide range of molding temperatures and low thickness dependence of fluidity, the content of structural unit (III) is preferably 25 mol% or less, more preferably 20 mol% or less, and even more preferably 15 mol% or less.

[0041] The liquid crystal polyester resin of the present invention preferably contains structural unit (IV) as a dioxy unit. Structural unit (IV) is a structural unit derived from hydroquinone. From the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of structural unit (IV) is preferably 1 mol% or greater, more preferably 4 mol% or greater, and even more preferably 7 mol% or greater, relative to 100 mol% of all structural units in the liquid crystal polyester resin. On the other hand, from the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of structural unit (IV) is preferably 30 mol% or less, more preferably 25 mol% or less, and even more preferably 20 mol% or less.

[0042] The liquid crystal polyester resin of the present invention preferably contains structural units (III) and (IV) in an amount of 2 mol% or more relative to 100 mol% of all structural units in the liquid crystal polyester resin. From the perspectives of enabling molding at a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the total amount of structural units (III) and (IV) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more.

[0043] On the other hand, the liquid crystal polyester resin of the present invention preferably contains structural units (III) and (IV) in an amount of 35 mol% or less relative to 100 mol% of all structural units in the liquid crystal polyester resin. From the perspectives of enabling molding at a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the total content of structural units (III) and (IV) is preferably 30 mol% or less, more preferably 25 mol% or less.

[0044] The liquid crystal polyester resin of the present invention preferably has a molar ratio ([III] / [IV]) of the contents of structural units (III) to (IV) greater than 0, more preferably 0.3 or greater, and even more preferably 0.6 or greater, from the viewpoints of being moldable over a wide range of molding temperatures, having excellent molding stability, and having low thickness dependence of fluidity. Furthermore, from the viewpoints of being moldable over a wide range of molding temperatures and having low thickness dependence of fluidity, [III] / [IV] is preferably less than 1.5, more preferably 1.2 or less, and even more preferably 1.0 or less.

[0045] In addition, as the dioxy units, structural units derived from aromatic diols such as resorcinol, tert-butylhydroquinone, phenylhydroquinone, chlorohydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, and 4,4'-dihydroxybenzophenone; structural units derived from aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; and structural units derived from alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol can be used within the range that does not impair the effects of the present invention.

[0046] The liquid crystal polyester resin of the present invention preferably contains 2 mol% or more of structural units (V) as dicarbonyl units, relative to 100 mol% of all structural units in the liquid crystal polyester resin. Structural units (V) are structural units derived from terephthalic acid. To ensure moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of structural units (V) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more.

[0047] On the other hand, the liquid crystal polyester resin of the present invention preferably contains 35 mol% or less of the structural units (V) relative to 100 mol% of all structural units in the liquid crystal polyester resin. From the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of the structural units (V) is preferably 30 mol% or less, more preferably 25 mol% or less.

[0048] Furthermore, the liquid crystal polyester resin of the present invention preferably comprises the following structural units (II) and (VI) and satisfies the following requirements (e) and (f). 0.01≦[Ⅵ]≦10 …(e) [VI] / [II]<1 …(f) [II] and [VI] represent the contents (in mol %) of the structural units (II) and (VI) relative to 100 mol % of all the structural units of the liquid crystal polyester resin.

[0049] [Chemistry 5]

[0050] The liquid crystal polyester resin of the present invention preferably contains 0.01 mol% or more of the structural unit (VI) as a dicarbonyl unit, relative to 100 mol% of all structural units in the liquid crystal polyester resin. The structural unit (VI) is derived from isophthalic acid. To ensure moldability over a wide range of molding temperatures, excellent molding stability, and minimal thickness dependence of fluidity, the content of the structural unit (VI) is preferably 0.05 mol% or more, more preferably 0.1 mol% or more.

[0051] On the other hand, the liquid crystal polyester resin of the present invention preferably contains 10 mol% or less of the structural unit (VI) relative to 100 mol% of all structural units in the liquid crystal polyester resin. From the perspectives of moldability over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the content of the structural unit (VI) is preferably 7 mol% or less, more preferably 4 mol% or less.

[0052] Furthermore, as the dicarbonyl unit, structural units derived from aromatic dicarboxylic acids such as 2,6-naphthalene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 3,3'-diphenyl dicarboxylic acid, 2,2'-diphenyl dicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, and 4,4'-diphenyl ether dicarboxylic acid; structural units derived from aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, and hexahydroterephthalic acid; and structural units derived from alicyclic dicarboxylic acids such as 1,4-cyclohexane dicarboxylic acid and 1,3-cyclohexane dicarboxylic acid can be used within a range that does not impair the effects of the present invention.

[0053] The liquid crystal polyester resin of the present invention preferably has a molar ratio ([VI] / [II]) of less than 1 between the contents of the structural units (VI) and (II). From the perspectives of enabling molding over a wide range of molding temperatures, excellent molding stability, and low thickness dependence of fluidity, the molar ratio ([VI] / [II]) of the contents of the structural units (VI) and (II) is preferably 0.9 or less. While the lower limit of [VI] / [II] is not particularly limited, it is preferably 0.005 or greater. From the perspectives of enabling molding over a wide range of molding temperatures and low thickness dependence of fluidity, the ratio [VI] / [II] is preferably 0.01 or greater, more preferably 0.05 or greater.

[0054] The liquid crystal polyester resin of the present invention preferably contains all of the following structural units (I) to (VI) and satisfies the following requirements (g) to (l), from the viewpoint of being able to more easily control the aforementioned temperature sensitivity coefficient and curing onset temperature within preferred ranges, being moldable over a wide range of molding temperatures, having excellent molding stability, and having low thickness dependence of fluidity. 25≦[I]≦75 …(g) 1≦[II]≦20 …(h) 2≦[III]+[IV]≦35 …(i) 2≦[V]≦35 …(j) 0.01≦[VI]≦10 …(k) [VI] / [II]<1 …(l) [I] to [V] represent the content (mol %) of each structural unit (I) to (VI) relative to 100 mol % of all structural units of the liquid crystal polyester resin.

[0055] [Chemistry 6]

[0056] The structural units (I) to (VI) are as described above.

[0057] Furthermore, in the liquid crystal polyester resin, in addition to the above-mentioned structural units (I) to (VI), structural units derived from p-aminobenzoic acid, p-aminophenol, etc. may be used within a range that does not impair the effects of the present invention.

[0058] The liquid crystal polyester resin of the present invention, by containing all of the aforementioned structural units (I) to (VI) within the aforementioned range, can achieve the following advantages of the present invention: The aforementioned temperature sensitivity coefficient and curing onset temperature can be more easily controlled within the optimal range, enabling molding over a wide range of molding temperatures, exhibiting excellent molding stability, and exhibiting a low thickness dependence of fluidity, which is advantageous. Without impairing the advantages of the present invention, the total content of the aforementioned structural units (I) to (VI) is preferably 99 mol% or greater, more preferably 99.5 mol% or greater, and even more preferably 100 mol% relative to 100 mol% of all structural units in the liquid crystal polyester resin.

[0059] Furthermore, the ratio of the total amount of the structural units (III) and (IV) to the total amount of the structural units (V) and (VI) ([III] + [IV]) / ([V] + [VI]) is preferably 0.9 or more and 1.1 or less from the viewpoint of controlling polymerization properties.

[0060] The monomers used as raw materials for each of the aforementioned structural units are not particularly limited as long as they can form the structure of each structural unit. Alternatively, derivatives of the hydroxyl groups of these monomers that have been acylated, or carboxylic acid derivatives in which the carboxyl groups have been esterified, acylated, or anhydrided, may also be used.

[0061] The following method is used to calculate the content of each structural unit in liquid crystal polyester resins. First, the liquid crystal polyester resin is pulverized, tetramethylammonium hydroxide is added, and thermal decomposition GC / MS analysis is performed using a GC / MS analyzer (e.g., Shimadzu GCMS-QP5050A). The content of each structural unit can be determined. Structural units that are not detected or below the detection limit are calculated as 0 mol%.

[0062] From the perspective of heat resistance, the melting point (Tm) of the liquid crystal polyester resin is preferably 280°C or higher, more preferably 300°C or higher, and even more preferably 320°C or higher. On the other hand, from the perspective of processability, the melting point (Tm) of the liquid crystal polyester resin is preferably 370°C or lower, more preferably 360°C or lower, and even more preferably 350°C or lower. Tm is a value measured using a differential scanning calorimeter in the manner described below.

[0063] From the perspective of heat resistance, the melt viscosity of the liquid crystal polyester resin is preferably 3 Pa·s or higher, more preferably 5 Pa·s or higher, and even more preferably 7 Pa·s or higher. From the perspective of fluidity, the melt viscosity of the liquid crystal polyester resin is preferably 50 Pa·s or lower, more preferably 30 Pa·s or lower, and even more preferably 20 Pa·s or lower.

[0064] In addition, the melt viscosity is the value measured by a high-pressure flow tester at a temperature of 20°C above the melting point (Tm) of the liquid crystal polyester resin and a shear rate of 1000 / s.

[0065] <Method for producing liquid crystal polyester resin> The method for producing the liquid crystal polyester resin of the present invention includes: copolymerizing monomers imparting structural units (I) to (VI) at a content within the above-mentioned range; or blending two or more liquid crystal polyester resins obtained by copolymerizing monomers imparting structural units (I) to (VI) at a content outside the above-mentioned range to adjust the content of structural units (I) to (VI) to the above-mentioned range. The method of copolymerizing monomers imparting structural units (I) to (VI) at a content within the above-mentioned range is preferred because it is easy to control the aforementioned temperature sensitivity coefficient and curing onset temperature within the preferred range without inheriting the properties of the liquid crystal polyester resin before blending, enabling molding over a wide range of molding temperatures, providing excellent molding stability, and reducing the thickness dependence of fluidity.

[0066] The method for producing the liquid crystal polyester resin of the present invention is not particularly limited, and known polyester polycondensation methods can be used. From the perspective of controlling the aforementioned temperature sensitivity coefficient and curing onset temperature within preferred ranges, a preferred method for producing a liquid crystal polyester resin composed of structural units (I) to (VI) is to react acetic anhydride with p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, terephthalic acid, and isophthalic acid to acetylate the phenolic hydroxy groups, followed by deacetylation polymerization to produce the liquid crystal polyester resin.

[0067] Furthermore, in the aforementioned manufacturing method, by satisfying the following requirements 1 to 3, it is easy to control the aforementioned temperature sensitivity coefficient and curing start temperature within an optimal range, which is therefore preferred. 1. Catalyst-free deacetylating polymerization. 2. Carry out deacetic acid polymerization under elevated temperature conditions, with an average heating rate from 145°C to 270°C set at 0.3-0.8°C / min. 3. In the step of acetylation of the monomer, the amount of acetic anhydride used is 1.05-1.20 molar equivalents of the total phenolic hydroxyl groups of the aromatic hydroxycarboxylic acid and the aromatic diol.

[0068] Regarding requirement 1 above, adding a catalyst during deacetylating polymerization accelerates the reaction and induces the formation of long chains composed of aromatic hydroxycarboxylic acids. Because long chains of aromatic hydroxycarboxylic acids are highly crystalline, the inclusion of long chains in liquid crystal polyester resins improves physical properties such as heat resistance. However, these long chains can cause unmelted crystals and foreign matter to form, and solidification and crystallization proceed rapidly from the molten state, making control of the aforementioned temperature sensitivity coefficient and curing initiation temperature difficult. Therefore, it is preferable to perform deacetylating polymerization without a catalyst. Specific examples of catalysts used when adding a catalyst include metal salts containing alkali metal or alkaline earth metal salts such as stannous acetate, tetrabutyl titanate, sodium carbonate, or calcium carbonate; metal salts composed of organic acids such as potassium acetate and sodium acetate and alkali metal or alkaline earth metal salts; antimony trioxide, and magnesium metal.

[0069] Regarding requirement 2 above, the polymerization temperature range of 145°C to 270°C is used to advance from the acetylation of the aromatic hydroxycarboxylic acid and the aromatic diol to oligomer formation. By setting the average temperature rise rate to 0.3°C to 0.8°C / minute, oligomer formation is facilitated by transesterification, thereby promoting the randomization of the main chain units. This suppresses the formation of long chains of the aromatic hydroxycarboxylic acid, making it easier to control the temperature sensitivity coefficient and the curing initiation temperature. The average temperature rise rate is preferably 0.35°C / minute or higher, more preferably 0.4°C / minute or higher. Furthermore, the average temperature rise rate is preferably 0.7°C / minute or lower, more preferably 0.65°C / minute or lower, and even more preferably 0.6°C / minute or lower.

[0070] Regarding requirement 3 above, by setting the amount of acetic anhydride to 1.05 to 1.20 molar equivalents relative to the total phenolic hydroxyl groups, the molecular weight increase process from oligomer formation is facilitated by transesterification, thereby promoting the randomization of the main chain structural units. This suppresses the formation of long aromatic hydroxycarboxylic acid chains, making it easier to control the temperature sensitivity coefficient and curing onset temperature. The amount of acetic anhydride is preferably 1.06 molar equivalents or greater, more preferably 1.07 molar equivalents or greater. Furthermore, the amount of acetic anhydride is preferably 1.18 molar equivalents or less, more preferably 1.15 molar equivalents or less.

[0071] As described above, by satisfying the above requirements 1 to 3, the formation of long chains of aromatic hydroxycarboxylic acids in the liquid crystal polyester resin can be suppressed, thereby making it easier to control the aforementioned temperature sensitivity coefficient and curing onset temperature within a preferred range.

[0072] <Filling material> In order to impart mechanical strength and other properties to the liquid crystal polyester resin, a liquid crystal polyester resin composition containing the liquid crystal polyester resin of the present invention and a filler can also be prepared. The filler used in the present invention is not particularly limited, and examples thereof include fibrous, whisker-like, plate-like, powdered, and granular fillers. Specifically, examples of fibrous and whisker-like fillers include glass fibers; PAN-based or pitch-based carbon fibers; metal fibers such as stainless steel fibers, aluminum fibers, or brass fibers; organic fibers such as aromatic polyamide fibers or liquid crystal polyester fibers; gypsum fibers, ceramic fibers, asbestos fibers, zirconium oxide fibers, aluminum oxide fibers, silica fibers, titanium oxide fibers, silicon carbide fibers, rock wool, potassium titanate whiskers, barium titanate whiskers, aluminum borate whiskers, silicon nitride whiskers, and needle-shaped titanium oxide. Examples of plate-like fillers include mica, talc, kaolin, glass flakes, clay, molybdenum disulfide, and wollastonite. Examples of powdered or granular fillers include silicon dioxide, glass beads, titanium oxide, zinc oxide, calcium polyphosphate, and graphite. The surfaces of these fillers may be treated with a surface treatment agent such as a known coupling agent (e.g., a silane-based coupling agent or a titanate-based coupling agent). Furthermore, two or more of these fillers may be used in combination.

[0073] Among the aforementioned fillers, glass fiber is particularly preferred due to its excellent mechanical strength, such as tensile strength and flexural strength, heat resistance, and dimensional stability. The type of glass fiber is not particularly limited as long as it is commonly used to reinforce resins. Examples include long-fiber and short-fiber chopped strands and milled fibers. Plate-shaped fillers are also preferred due to their excellent thin-wall flowability.

[0074] The surface of the glass fiber can be treated with a known surface treatment agent (e.g., a silane-based coupling agent, a titanate-based coupling agent, etc.). Furthermore, the glass fiber can be coated or bundled with a thermoplastic resin such as ethylene / vinyl acetate copolymer or a thermosetting resin such as epoxy resin.

[0075] The liquid crystal polyester resin composition of the present invention may further contain conventional additives selected from antioxidants, heat stabilizers (e.g., hindered phenols, hydroquinones, phosphites, thioethers, and substituted derivatives thereof), ultraviolet absorbers (e.g., resorcinol, salicylates), anti-discoloration agents such as phosphites and hypophosphites, lubricants and mold release agents (e.g., octacosic acid and its metal salts, esters, and half-esters, stearyl alcohol, stearamide, and polyethylene wax), colorants including dyes or pigments, conductive agents or carbon black as a colorant, crystal nucleating agents, plasticizers, flame retardants (e.g., brominated flame retardants, phosphorus flame retardants, red phosphorus, and silicone flame retardants), flame retardant adjuvants, and antistatic agents, within a range that does not impair the effects of the present invention.

[0076] In the liquid crystal polyester resin composition of the present invention, the filler content is preferably 10 to 200 parts by weight per 100 parts by weight of the liquid crystal polyester resin. A filler content of 10 parts by weight or greater can improve the mechanical strength of the molded article. A filler content of 15 parts by weight or greater is more preferably 20 parts by weight or greater. On the other hand, a filler content of 200 parts by weight or less is preferred, as it provides a liquid crystal polyester resin composition with excellent moldability and thin-wall flowability, and facilitates injection molding of small, thin-walled molded articles. The filler content is more preferably 150 parts by weight or less, and even more preferably 100 parts by weight or less.

[0077] The fillers and additives can be prepared by, for example, dry blending the filler and other solid additives into the liquid crystal polyester resin; solution blending the filler and other liquid additives into the liquid crystal polyester resin; adding the filler and other additives during polymerization of the liquid crystal polyester resin; or melt-kneading the filler and other additives into the liquid crystal polyester resin. The melt-kneading method is preferred.

[0078] Melt kneading can be performed using known methods. Examples of apparatus for melt kneading include an internal mixer, a rubber roll mill, a kneader, and a single- or twin-screw extruder. Twin-screw extruders are preferred. The melt kneading temperature is preferably at least the melting point of the liquid crystal polyester resin and no more than 50°C above the melting point.

[0079] The kneading methods include: 1) a method of uniformly feeding the liquid crystal polyester resin, filler and other additives from a rear feeder and kneading them (uniform kneading method); 2) a method of feeding the liquid crystal polyester resin and other additives from a rear feeder and kneading them, and then adding the filler and other additives as needed from a side feeder and kneading them (side feeding method); 3) a method of preparing a liquid crystal polyester composition (main particles) containing other additives at a high concentration in the liquid crystal polyester resin, and then kneading the main particles with the liquid crystal polyester resin and filler so that the additives have a predetermined concentration (main particle method), etc.

[0080] <Molded products> The liquid crystal polyester resin and liquid crystal polyester resin composition of the present invention can be processed into molded articles having excellent surface appearance (color tone), mechanical properties, and heat resistance through melt molding methods such as injection molding, extrusion molding, and spinning; and molding methods such as stamping molding and solution casting film formation. Molded articles herein include injection molded articles, extrusion molded articles, stamping molded articles, sheets, tubes, various films such as unstretched films, uniaxially stretched films, and biaxially stretched films; and various fibers such as unstretched yarns and ultra-stretched yarns. Injection molding is particularly preferred from the perspective of processability. During melt molding, to suppress degradation of the liquid crystal polyester resin composition and enhance mechanical strength, melt molding at a temperature of 370°C or lower is preferred, and 360°C or lower is more preferred.

[0081] Molded articles obtained by molding the liquid crystal polyester resin and liquid crystal polyester resin composition of the present invention can be preferably used as electrical and electronic components. Examples of such components include flexible printed circuit boards, laminated circuit boards, printed wiring boards, and three-dimensional circuit boards used in antennas for personal computers, GPS devices, mobile phones, millimeter-wave and quasi-millimeter-wave radars such as collision avoidance radars, and mobile communication and electronic devices such as tablets and smartphones; reflectors and sockets for LED lamps, small or micro-battery components for mobile communication terminal base stations; antenna covers, housings, sensors, actuator components for camera modules; connectors, relay cases and bases, switches, bobbins, and capacitors. These components are particularly useful for connectors, relays, switches, bobbins, and actuator components for camera modules, due to their ability to be molded over a wide range of molding temperatures and their low dependence on thickness for fluidity. [Example]

[0082] The present invention is described below using examples, but the present invention is not limited to the examples. In the examples, the composition and properties of the liquid crystal polyester resin were measured by the following methods.

[0083] (1) Composition analysis of liquid crystal polyester resin To 0.1 mg of crushed liquid crystal polyester resin particles, 2 μL of a 25% methanol solution of tetramethylammonium hydroxide was added. Thermal decomposition GC / MS analysis was performed using a Shimadzu GCMS-QP5050A to determine the composition ratio of the components in the liquid crystal polyester resin.

[0084] (2) Determination of melting point (Tm) of liquid crystal polyester resin The liquid crystal polyester resin was heated at a rate of 20°C / min from room temperature using a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer). The observed endothermic peak temperature (Tm 1) was measured. The resin was then held at Tm 1 + 20°C for 5 minutes, then cooled to room temperature at a rate of 20°C / min. The resin was then heated again at a rate of 20°C / min from room temperature to Tm 1 + 20°C. The observed endothermic peak temperature was used as the melting point (Tm).

[0085] (3) Melt viscosity of liquid crystal polyester resin Using a high-pressure flow tester CFT-500D (orifice 0.5 The melt viscosity of liquid crystal polyester resin was measured at a temperature of Tm + 20°C and a shear rate of 1000 / s.

[0086] (4) Evaluation of forming temperature range After drying the liquid crystal polyester resin at 150°C for 3 hours in a hot air dryer, the resin was fed to a FNAUC α30C injection molding machine (manufactured by FNAUC). Using a mold capable of forming molded parts measuring 5.0 mm wide, 50 mm long, and 0.2 mm thick, the molding pressure was adjusted to achieve an average molded part length of 40 mm, and 100 consecutive molding cycles were performed under molding conditions of 90°C mold temperature and 200 mm / s injection speed. Molding was performed while varying the cylinder temperature in 5°C increments within the range of the liquid crystal polyester resin's melting point ±0°C to its melting point +40°C. For the resulting test pieces, the cylinder temperature at which no more than 5 shots out of 100 shots were produced with a length of 39 mm or less or 41 mm or greater was defined as the moldable temperature. The moldable temperature range was calculated as (maximum moldable temperature) minus (minimum moldable temperature). A larger value indicates a wider moldable temperature range.

[0087] (5) Evaluation of thickness dependence of fluidity After drying the liquid crystal polyester resin at 150°C for 3 hours in a hot air dryer, the resin was fed to a FNAUC α30C injection molding machine (manufactured by FNAUC). Using a mold capable of molding articles measuring 5.0 mm wide, 50 mm long, and 0.2 mm thick, the molding conditions were adjusted to achieve an average length of 40 mm for the resulting molded articles, with a cylinder temperature set to the melting point of the liquid crystal polyester resin + 10°C, a mold temperature of 90°C, and an injection speed of 200 mm / s. The mold was then replaced with a mold capable of molding articles measuring 5.0 mm wide, 50 mm long, and 0.5 mm thick at the flow end. Ten molds were then molded under the same molding conditions, with the average flow length at the 0.2 mm thickness section of the resulting molded articles calculated. A greater flow length at the 0.2 mm thickness section indicates less thickness dependence of the fluidity, and is considered excellent.

[0088] (6) Forming stability (evaluation of the number of injections required for recovery) The liquid crystal polyester resin pellets obtained from each embodiment and comparative example were dried with hot air at 150°C for 3 hours using a hot air dryer and then supplied to an FNAUC α30C injection molding machine manufactured by FNAUC. The injection cylinder temperature was set to the melting point of the liquid crystal polyester + 15°C, the mold temperature was set to 90°C, the injection pressure was set to 100 MPa, and the speed was set to the minimum filling speed. Injection molding was performed to obtain the connector molded product shown in Figure 3. Figure 3 is a three-dimensional view of the connector molded product, which has a long dimension surface (2) and a short dimension surface (3), and an outer dimension of width (6) 3 mm × height (5) 2 mm × length (4) 30 mm. It has terminals divided by a partition wall (8), the distance (7) between the terminals is 0.4 mm, and the thickness of the partition wall (8), which is the minimum wall thickness of the product, is 0.2 mm. Liquid crystal polyester resin or resin composition is filled from the needle-shaped gate G1 (gate diameter 0.3 mm) provided on the short dimension surface (3) on one side of the connector molded product, and is fully filled to the wall corner on the opposite side of the gate. After 100 injection moldings are performed continuously, the molding is temporarily stopped, the injection cylinder temperature is lowered to 150°C, and the mold is left to stand for 120 minutes. Thereafter, the injection cylinder temperature is raised to the melting point of the liquid crystal polyester + 15°C, and the same liquid crystal polyester resin or resin composition as in the above molding is used. After one flushing injection, continuous molding is performed under the same conditions and the same mold, and the number of injections required to obtain a molded product fully filled to the wall corner on the opposite side of the gate, i.e., the number of injections required for recovery, is evaluated in the same manner as in the above molding. The wall corner is a portion that is easily left unfilled after recovery. When the number of injections required for recovery is less than 10, the molding stability is excellent.

[0089] (7) Evaluation of temperature sensitivity coefficient and curing starting temperature After drying the liquid crystal polyester resin at 150°C for 3 hours in a hot air dryer, the rheometer Physica MCR501 (manufactured by Anton Paar) was used for measurement as follows. The liquid crystal polyester resin was placed between 25 mm diameter parallel plates. In the rheometer's oscillatory measurement mode, the gap between the plates was set to 1 mm, the strain was 10%, and the frequency was 1 Hz. After maintaining the temperature at Tm + 30°C for 5 minutes, the temperature was then decreased at a rate of 0.17°C / second to a complex viscosity of 50,000 (Pa·s). A rheometer spectrum was obtained, with the x-axis plotted as ΔT (°C) = measurement temperature - Tm (°C) and the y-axis plotted as the logarithm of the complex viscosity (log(η(Pa·s))). The rheometer spectrum curve 1 shown in Figure 1 was obtained. Based on the obtained rheometer spectrum, the absolute value of the slope (temperature sensitivity coefficient) of the straight line w connecting B(x) (the curing onset temperature), point A, and point B was calculated according to the aforementioned procedure. In addition, the temperature sensitivity coefficient is calculated using the following formula: Temperature sensitivity coefficient = |(log(η(Pa·s)) of point A - log(η(Pa·s)) of point B) / (20-B(x))|.

[0090] [Example 1] In a 5 L reaction vessel equipped with a stirring blade and a distillation tube, 808 parts by weight of p-hydroxybenzoic acid (HBA), 88 parts by weight of 6-hydroxy-2-naphthoic acid (HNA), 229 parts by weight of 4,4'-dihydroxybiphenyl (DHB), 161 parts by weight of hydroquinone (HQ), 428 parts by weight of terephthalic acid (TPA), 19 parts by weight of isophthalic acid (IPA), and 1278 parts by weight of acetic anhydride (1.07 equivalents of phenolic hydroxyl groups combined) were added. The mixture was stirred under a nitrogen atmosphere and reacted at 145°C for 120 minutes. The temperature was then raised from 145°C to 360°C over 4 hours (with an average heating rate of 0.9°C / minute from 145°C to 270°C). The polymerization temperature was then maintained at 360°C, and the pressure was reduced to 1.0 mmHg (133 Pa) over 1.0 hour. The reaction was continued until polymerization was completed when a predetermined stirring torque was reached. Next, the polymer was ejected into strands through a nozzle having a circular nozzle hole with a diameter of 6 mm, and pelletized by a cutter to obtain a liquid crystal polyester resin (A-1).

[0091] [Example 2] Liquid crystal polyester resin (A-2) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 776 parts by weight of HBA, 66 parts by weight of HNA, 251 parts by weight of DHB, 168 parts by weight of HQ, 447 parts by weight of TPA, and 29 parts by weight of IPA.

[0092] [Example 3] A liquid crystal polyester resin (A-3) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 1018 parts by weight of HBA, 264 parts by weight of HNA, 44 parts by weight of DHB, 135 parts by weight of HQ, 214 parts by weight of TPA, and 29 parts by weight of IPA.

[0093] [Example 4] A liquid crystal polyester resin (A-4) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 905 parts by weight of HBA, 88 parts by weight of HNA, 109 parts by weight of DHB, 193 parts by weight of HQ, 321 parts by weight of TPA, and 68 parts by weight of IPA.

[0094] [Example 5] A liquid crystal polyester resin (A-5) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 469 parts by weight of HBA, 242 parts by weight of HNA, 131 parts by weight of DHB, 309 parts by weight of HQ, 564 parts by weight of TPA, and 19 parts by weight of IPA.

[0095] [Example 6] A liquid crystal polyester resin (A-6) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 986 parts by weight of HBA, 88 parts by weight of HNA, 360 parts by weight of DHB, 13 parts by weight of HQ, 321 parts by weight of TPA, and 19 parts by weight of IPA.

[0096] [Example 7] A liquid crystal polyester resin (A-7) was obtained in the same manner as in Example 1, except that the monomer amounts were changed to 792 parts by weight of HBA, 88 parts by weight of HNA, 251 parts by weight of DHB, 155 parts by weight of HQ, 457 parts by weight of TPA, and 1314 parts by weight of acetic anhydride (1.10 equivalents of the total phenolic hydroxyl groups), and the temperature was increased from 145°C to 270°C at an average heating rate of 0.5°C / min.

[0097] [Example 8] A liquid crystal polyester resin (A-8) was obtained in the same manner as in Example 1, except that the monomer amounts were changed to 905 parts by weight of HBA, 88 parts by weight of HNA, 436 parts by weight of DHB, 321 parts by weight of TPA, 68 parts by weight of IPA, and 1314 parts by weight of acetic anhydride (1.10 equivalents of the total phenolic hydroxyl groups), and the temperature was increased at an average heating rate of 0.5°C / min from 145°C to 270°C.

[0098] [Example 9] A liquid crystal polyester resin (A-9) was obtained in the same manner as in Example 1 except that the temperature was increased at an average temperature increase rate of 0.5°C / min from 145°C to 270°C.

[0099] [Comparative Example 1] A liquid crystal polyester resin (A'-10) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 870 parts by weight of HBA, 352 parts by weight of DHB, 89 parts by weight of HQ, 292 parts by weight of TPA, and 157 parts by weight of IPA.

[0100] [Comparative Example 2] A liquid crystal polyester resin (A'-11) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 808 parts by weight of HBA, 88 parts by weight of HNA, 501 parts by weight of DHB, 408 parts by weight of TPA, and 39 parts by weight of IPA.

[0101] [Comparative Example 3] A liquid crystal polyester resin (A'-12) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 970 parts by weight of HBA, 88 parts by weight of HNA, 196 parts by weight of DHB, 116 parts by weight of HQ, and 350 parts by weight of TPA.

[0102] [Comparative Example 4] A liquid crystal polyester resin (A'-13) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 743 parts by weight of HBA, 176 parts by weight of HNA, 296 parts by weight of HQ, 292 parts by weight of TPA, and 156 parts by weight of IPA.

[0103] [Comparative Example 5] A liquid crystal polyester resin (A'-14) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 937 parts by weight of HBA, 44 parts by weight of HNA, 261 parts by weight of DHB, 3 parts by weight of HQ103 parts by weight, 292 parts by weight of TPA, and 97 parts by weight of IPA.

[0104] [Comparative Example 6] A liquid crystal polyester resin (A'-15) was obtained in the same manner as in Example 1, except that the monomer amounts were changed to 792 parts by weight of HBA, 88 parts by weight of HNA, 251 parts by weight of DHB, 155 parts by weight of HQ, 457 parts by weight of TPA, and 1231 parts by weight of acetic anhydride (1.03 equivalents of phenolic hydroxyl groups in total), 1 part by weight of potassium acetate was added as a catalyst, and the temperature was increased from 145°C to 270°C at an average heating rate of 0.5°C / min.

[0105] [Comparative Example 7] A liquid crystal polyester resin (A'-16) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 792 parts by weight of HBA, 88 parts by weight of HNA, 251 parts by weight of DHB, 155 parts by weight of HQ, and 457 parts by weight of TPA.

[0106] [Comparative Example 8] A liquid crystal polyester resin (A'-17) was obtained in the same manner as in Example 1 except that the monomer addition amounts were changed to 905 parts by weight of HBA, 88 parts by weight of HNA, 436 parts by weight of DHB, 321 parts by weight of TPA, and 68 parts by weight of IPA.

[0107] The liquid crystal polyester resins obtained in Examples 1 to 9 and Comparative Examples 1 to 8 were evaluated according to the above (1) to (7), and the results are shown in Tables 1 and 2.

[0108] [Table 1] Table 1 Liquid crystal polymer Ester resin Structural unit (I) (Molar %) Structural unit (II) (Molar %) Structural unit (III) (Molar %) Building block (IV) (Molar %) Building block (III)+ Structural unit (IV) (mol %) Structural unit (V) (Molar %) Building Block (VI) (Molar %) [VI] / [II] [III] / [IV] [I] / [II] Example 1 A-1 50.0 4.0 10.5 12.5 23.0 22.0 1.0 0.25 0.84 12.5 Example 2 A-2 48.0 3.0 11.5 13.0 24.5 23.0 1.5 0.50 0.88 16.0 Example 3 A-3 63.0 12.0 2.0 10.5 12.5 11.0 1.5 0.13 0.19 5.3 Example 4 A-4 56.0 4.0 5.0 15.0 20.0 16.5 3.5 0.88 0.33 14.0 Example 5 A-5 29.0 11.0 6.0 24.0 30.0 29.0 1.0 0.09 0.25 2.6 Example 6 A-6 61.0 4.0 16.5 1.0 17.5 16.5 1.0 0.25 16.50 15.3 Example 7 A-7 49.0 4.0 11.5 12.0 23.5 23.5 0.0 0.00 0.95 12.3 Example 8 A-8 56.0 4.0 20.0 0.0 20.0 16.5 3.5 0.88 Unable to calculate 10.6 Example 9 A-9 50.0 4.0 10.5 12.5 23.0 22.0 1.0 0.25 0.84 12.5 Comparative Example 1 A'-10 53.8 0.0 16.2 6.9 23.1 15.0 8.1 Unable to calculate 2.33 Unable to calculate Comparative Example 2 A'-11 50.0 4.0 23.0 0.0 23.0 21.0 2.0 0.50 Unable to calculate 12.5 Comparative Example 3 A'-12 60.0 4.0 9.0 9.0 18.0 18.0 0.0 0.00 1.00 15.0 Comparative Example 4 A'-13 46.0 8.0 0.0 23.0 23.0 15.0 8.0 1.00 0.00 5.8 Comparative Example 5 A'-14 58.0 2.0 12.0 8.0 20.0 15.0 5.0 2.50 1.50 29.0 Comparative Example 6 A'-15 49.0 4.0 11.5 12.0 23.5 23.5 0.0 0.00 0.95 12.3 Comparative Example 7 A'-16 49.0 4.0 11.5 12.0 23.5 23.5 0.0 0.00 0.95 12.3 Comparative Example 8 A'-17 56.0 4.0 20.0 0.0 20.0 16.5 3.5 0.20 Unable to calculate 10.6

[0109] [Table 2] Table 2 Liquid crystal polymer Ester resin Tm (℃) Melt viscosity (Pa·s) Forming temperature Degree range (℃) Thick fluidity Degree dependence (mm) Forming recovery (indivual) Point A log (η(Pa·s)) log(η(Pa·s)) of point B Curing start temperature (℃) (ΔT at point B) Temperature sense Stress coefficient Example 1 A-1 332 12 40 20.5 5 1.52 210 -25.5 0.013 Example 2 A-2 332 12 40 20.5 5 1.48 2.08 -26.0 0.013 Example 3 A-3 335 12 30 18.0 7 1.78 2.48 -24.0 0.016 Example 4 A-4 335 12 35 19.0 6 1.43 2.08 -27.0 0.014 Example 5 A-5 333 12 30 18.0 7 1.70 2.30 -20.0 0.016 Example 6 A-6 331 12 25 17.0 7 1.60 2.26 -19.0 0.017 Example 7 A-7 335 12 20 17.0 7 1.70 2.40 -19.0 0.018 Example 8 A-8 336 12 20 16.0 8 1.70 2.43 -20.0 0.018 Example 9 A-9 332 12 40 21.5 4 1.54 2.04 -26.0 0.011 Comparative Example 1 A'-10 310 12 15 13.5 twenty four 1.48 2.74 -22.0 0.030 Comparative Example 2 A'-11 332 12 15 14.5 14 1.15 2.40 -25.0 0.028 Comparative Example 3 A'-12 335 12 15 14.5 12 1.40 2.54 -23.0 0.027 Comparative Example 4 A'-13 333 12 10 13.0 14 1.30 2.36 -17.0 0.029 Comparative Example 5 A'-14 322 12 10 13.0 13 1.30 2.40 -21.0 0.027 Comparative Example 6 A'-15 337 12 10 12.0 16 1.70 2.70 -13.0 0.030 Comparative Example 7 A'-16 336 12 10 13.0 13 1.48 2.60 -22.0 0.027 Comparative Example 8 A'-17 338 12 10 13.5 12 1.40 2.54 -23.0 0.027

[0110] Fillers were further added to the liquid crystal polyester resins obtained in Example 1 and Comparative Example 5 to produce liquid crystal polyester resin compositions. The fillers used in each of the Examples and Comparative Examples are as follows.

[0111] Filler (B) (B-1) Milled fiber made by Nippon Electric Glass (40M-10A) [Example 10, Comparative Example 9] A TEM35B twin-screw extruder manufactured by Toshiba Machine, equipped with a side feeder, was used. The liquid crystal polyester resins (A-1 and A'-14) obtained in each manufacturing example were fed from the feed hopper in the amounts shown in Table 3. The filler (B-1) was fed from the side feeder in the amounts shown in Table 3. The cylinder temperature was set to the melting point of the liquid crystal polyester resin + 10°C, and melt-kneading was performed to obtain pellets. The pellets of the obtained liquid crystal polyester resin composition were dried with hot air and then evaluated in the same manner as (4) to (6). The results are shown in Table 3.

[0112] [Table 3] Table 3 Liquid crystal polyester resin (parts by weight) Filler (parts by weight) Forming temperature range (℃) Thickness dependence of fluidity (mm) Forming recovery (quantity) Example 10 A-1(100) B-1(43) 40 15.0 6 Comparative Example 9 A'-14(100) B-1(43) 10 7.5 18

[0113] The results in Tables 1-3 demonstrate that by using a liquid crystal polyester resin with a temperature sensitivity coefficient of 0.020 or less and a curing onset temperature of -35°C to -15°C, or a liquid crystal polyester resin composition using such a resin, it is possible to obtain molded products that can be molded over a wide range of molding temperatures, exhibit excellent molding stability, and exhibit low thickness dependence of fluidity. (Industrial Applicability)

[0114] The liquid crystal polyester resin and liquid crystal polyester resin composition of the present invention can be molded over a wide range of molding temperatures, exhibit excellent molding stability, and exhibit low thickness dependence of fluidity. Therefore, they are suitable for applications in electrical and electronic components such as connectors, relays, switches, bobbins, and actuator parts for camera modules.

[0115] 1: Rheometer spectrum curve of liquid crystal polyester resin 2: Long size surface 3: Short size surface 4: Length 5: Height 6: Width 7: Distance between terminals 8: Next door A: The point where ΔT is 20°C on the rheometer spectrum curve A': The point on the rheometer spectrum curve where ΔT is 10°C B: The intersection of straight line v and the rheometer spectrum curve B': The intersection of the connecting line t and the line u B(x): ΔT value at point B (curing starting temperature) C: The point below the melting point on the rheometer spectrum curve where the complex viscosity is 10,000 Pa·s C': The point below the melting point on the rheometer spectrum curve and with a complex viscosity of 50,000 Pa·s on the rheometer spectrum curve G1: Needle gate L1: The straight line (straight line) representing the temperature sensitivity coefficient of S1, equivalent to w in Figure 1 L2: The straight line (straight line) representing the temperature sensitivity coefficient of S2, equivalent to w in Figure 1 S1: Example of rheometer spectrum curve of the liquid crystal polyester resin of the present invention (spectral curve) S2: Example of a conventional rheometer spectrum curve of a liquid crystal polyester resin (spectral curve) t: the straight line connecting point A' and point A u: the straight line connecting point C and point C' v: A straight line passing through point B' and parallel to the y-axis w: the straight line connecting point A and point B x, y: axis η: complex viscosity

Claims

1. A liquid crystal polyester resin comprising structural units derived from aromatic hydroxycarboxylic acids, structural units derived from aromatic diols, and structural units derived from aromatic dicarboxylic acids, wherein, The liquid crystal polyester resin contains, relative to 100 mol% of all its structural units, 15-80 mol% of structural units derived from aromatic hydroxycarboxylic acids, 2-40 mol% of structural units derived from aromatic diols, and 2-40 mol% of structural units derived from aromatic dicarboxylic acids; the liquid crystal polyester resin comprises structural units selected from the following structural units (I) to (V), satisfying the following conditions (a) to (d): 25≦[I]≦75 …(a) 1≦[II]≦20 …(b) 2≦[III]+[IV]≦35 …(c) 2≦[V]≦35 …(d) [I] to [V] represent the content (mol%) of each of the following structural units (I) to (V) relative to 100 mol% of all its structural units; [Chemical 1] and satisfies the following condition (α): (α): The temperature sensitivity coefficient measured as follows is below 0.020, and B(x) is -35 to -15℃; When the melting point of the liquid crystal polyester resin is set as Tm (℃), the liquid crystal polyester resin is measured using a rheometer as follows. In the rheometer spectrum of the liquid crystal polyester resin obtained by setting the x-axis as ΔT (℃) = measurement temperature - Tm (℃) and the y-axis as the logarithm of complex viscosity (log(η(Pa•s))), the point ΔT = 20℃ is set as point A, the point ΔT = 10℃ is set as point A', the point below the melting point and the complex viscosity η is 10000 Pa•s is set as point C, and the point with complex viscosity η of 5000 Pa•s is set as point C. Point C' is defined as the point in Pa•s. The line passing through points A and A' is defined as line t, the line passing through points C and C' is defined as line u, the intersection of line t and line u is defined as point B', the line passing through point B' and parallel to the y-axis is defined as line v, and the intersection of line v and the rheometer spectral curve is defined as point B. The absolute value of the slope of the line w connecting points A and B is defined as the temperature sensitivity coefficient, and the ΔT value of point B is defined as B(x). The above rheometer spectral curve was obtained in the vibration measurement mode of the rheometer, with the gap between the parallel plates set to 1 mm, the strain to 10%, and the frequency to 1 Hz. After being held at a temperature of Tm+30℃ for 5 minutes, the temperature was lowered at 0.17℃ / second to a temperature where the complex viscosity was 50000 (Pa•s). The melting point Tm of the aforementioned liquid crystal polyester resin is determined by differential calorimetry. After observing the endothermic peak temperature Tm1 when the liquid crystal polyester resin is heated from room temperature at a heating rate of 20°C / min, it is held at Tm1+20°C for 5 minutes, temporarily cooled to room temperature at a cooling rate of 20°C / min, and then heated again at a heating rate of 20°C / min.

2. The liquid crystal polyester resin of claim 1 contains structural units selected from the following structural units (Ⅰ) to (Ⅵ) and satisfies the following requirements (g) to (l): 25≦[I]≦75 …(g) 1≦[II]≦20 …(h) 2≦[III]+[IV]≦35 …(i) 2≦[V]≦35 …(j) 0.01≦[VI]≦10 …(k) [VI] / [II]<1 …(l) [I]~[VI] represents the content (mol%) of each of the following structural units (I)~(VI) relative to 100 mol% of all structural units of the liquid crystal polyester resin [Chemical 3].

3. The liquid crystal polyester resin of claim 1 or 2 further satisfies the following requirement (m): 0 < [III] / [IV] < 1.5 … (m) [III] and [IV] represent the content (in moles) of each of the aforementioned structural units (III) and (IV) relative to 100 moles of all structural units of the liquid crystal polyester resin.

4. The liquid crystal polyester resin of claim 2 further satisfies the following requirement (n): 99≦[I]+[II]+[III]+[IV]+[V]+[VI]≦100 …(n) [I]~[VI] represent the content (in moles%) of each of the aforementioned structural units (I)~(VI) relative to 100 moles of all structural units of the liquid crystal polyester resin.

5. A liquid crystal polyester resin composition, comprising 10 to 200 parts by weight of filler relative to 100 parts by weight of the liquid crystal polyester resin of any one of claims 1 to 4.

6. A molded article comprising a liquid crystal polyester resin of any one of claims 1 to 4, or a liquid crystal polyester resin composition of claim 5.

7. The molded article as claimed in item 6 is selected from any one of the group consisting of connectors, relays, switches, winding tubes and actuator parts of camera modules.

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