Liquid crystal polyester resin, liquid crystal polyester resin composition, and molded article made therefrom

Abstract

Provided is a liquid crystal polyester resin containing 20-80 mol% of a structural unit derived from an aromatic hydroxycarboxylic acid, 10-40 mol% of a structural unit derived from an aromatic diol, and 10-40 mol% of a structural unit derived from an aromatic dicarboxylic acid with respect to 100 mol% of the total structural units of the liquid crystal polyester resin. The liquid crystal polyester resin contains at least 15-75 mol% of a structural unit (I) (HBA) and 2-20 mol% of a structural unit (II) (HNA) as the aromatic hydroxycarboxylic acid. The liquid crystal polyester resin generates a phenol gas of 100 ppm or less when held at a melting point of +20°C for 60 minutes under a reduced pressure of 13.3 kPa or less. The obtained liquid crystal polyester resin has reduced metal corrosiveness during use in a high temperature environment and excels in the property of low warpage.

Description

Technical Field

[0001] The present invention relates to a liquid crystal polyester resin, a liquid crystal polyester resin composition, and a molded article made therefrom. More specifically, it relates to a liquid crystal polyester resin, a liquid crystal polyester resin composition, and a molded article obtained using the same.

Background Art

[0002] Liquid crystal polyester resins are used in electrical and electronic components that require such properties because they are excellent in heat resistance, fluidity, and dimensional stability. In recent years, due to the miniaturization of smartphones and the like, higher integration, thinner thickness, and lower profile of components are further demanded, so the materials are required to have thin-wall fluidity and low warpage. On the other hand, when the viscosity of the liquid crystal polyester resin is lowered to ensure thin-wall fluidity, the gas generated from the polymer during melt processing, particularly phenol gas, increases. Therefore, when the liquid crystal polyester resin is used in contact with metal parts such as terminals, phenol gas may be released when the molded article is processed at a high temperature such as during reflow, corroding the metal. In addition, due to the higher integration of components in recent years, they are used for a long time in a high-temperature environment, so phenol gas may also be released in the use environment, increasing corrosion.

[0003] Phenol gas is mainly caused by the thermal denaturation of p-hydroxybenzoic acid, which is often the main component of liquid crystal polyester resins, and is generated in large amounts during the polymerization or melt processing of the polymer. As a study to reduce the generated gas, for example, by controlling the acetylation rate of the aromatic diol used in the polymerization of the polymer to be lower than normal, acetic acid, phenol, and carbon dioxide gas generated when held at the melting point + 10 ° C for 30 minutes in a helium gas atmosphere are reduced. A liquid crystal polyester resin (for example, Patent Document 1) or a liquid crystal polyester resin in which generated gas such as phenol is reduced by including structural units derived from 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, and terephthalic acid without using p-hydroxybenzoic acid (for example, Patent Document 2) has been proposed.

[0004] In addition, a liquid crystal polyester resin (for example, Patent Document 3) has been proposed that has p-hydroxybenzoic acid as a main component and contains structural units derived from 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, and terephthalic acid, thereby reducing blisters derived from generated gas and improving flatness.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the technology described in Patent Document 1, although the amount of gas generated under an inert gas is defined, the metal corrosiveness in recent use under high-temperature environments has a high correlation with the amount of gas generated under reduced pressure, which is a more severe condition. In the method described in Patent Document 1, since the reduction of the amount of gas generated under reduced pressure is insufficient, although it has a certain effect on reducing metal corrosiveness, the metal corrosiveness in use under high-temperature environments is still insufficient. Furthermore, the liquid crystal polyester resin of Patent Document 1 also had problems with flatness. In the method described in Patent Document 2, although the amount of generated gas is reduced, since the reduction of the amount of gas generated under reduced pressure is insufficient, there are problems with metal corrosiveness in use under high-temperature environments. Furthermore, there were also problems with flatness. In addition, the method described in Patent Document 3 has no effect on reducing metal corrosiveness, and the flatness is still insufficient.

[0007] An object of the present invention is to provide a liquid crystal polyester resin, a liquid crystal polyester resin composition, and a molded article made therefrom that reduce metal corrosiveness during use in a high-temperature environment and are excellent in low warpage properties.

Means for Solving the Problems

[0008] As a result of intensive studies to solve the above problems, the present inventors have found that, based on 100 mol% of all structural units of the liquid crystal polyester resin, as the aromatic hydroxycarboxylic acid, at least 15 to 75 mol% of structural unit (I) and 2 to 20 mol% of structural unit (II) are included. A liquid crystal polyester resin in which the phenol gas generated under heating and reduced pressure is below a certain level reduces metal corrosiveness during use in a high-temperature environment and is excellent in low warpage properties, and thus the present invention has been achieved.

[0009] That is, the present invention is as follows: (1) A liquid crystal polyester resin containing 20 to 80 mol% of the following structural units derived from aromatic hydroxycarboxylic acids, 10 to 40 mol% of structural units derived from aromatic diols, and 10 to 40 mol% of structural units derived from aromatic dicarboxylic acids, based on 100 mol% of all structural units of the liquid crystal polyester resin. As the aromatic hydroxycarboxylic acid, it contains at least 15 to 75 mol% of structural unit (I) and 2 to 20 mol% of structural unit (II). The liquid crystal polyester resin, when held at the melting point + 20 °C for 60 minutes under a reduced pressure of 13.3 kPa or less, has a phenol gas generation of 100 ppm or less.

[0010]

Chemical formula

[0011] (2) The liquid crystal polyester resin according to (1), wherein structural unit (I) is 80 to 97 mol% based on 100 mol% of the total of structural units (I) and (II). (3) The liquid crystal polyester resin according to (1) or (2), wherein, based on 100 mol% of all the structural units of the liquid crystal polyester resin, the aromatic diol contains 2 to 20 mol% of the structural unit (III).

[0012]

Chemical formula

[0013] (4) The liquid crystal polyester resin according to any one of (1) to (3), wherein the aromatic diol contains the structural units (III) and (IV), and the structural unit (III) is 45 to 90 mol% based on 100 mol% of the total of the structural units (III) and (IV).

[0014]

Chemical formula

[0015] (5) A method for producing a liquid crystal polyester resin, which comprises reacting hydroxycarboxylic acid and / or diol with acetic anhydride to acetylate at least a part of phenolic hydroxyl groups, and then subjecting to deacetic acid polymerization with dicarboxylic acid, wherein the deacetic acid polymerization reaction at a temperature of 230 to 245 °C is carried out for 40 to 120 minutes. The method for producing a liquid crystal polyester resin according to any one of (1) to (4). (6) A liquid crystal polyester resin composition containing 10 to 200 parts by weight of a filler based on 100 parts by weight of the liquid crystal polyester resin according to any one of (1) to (4). (7) A molded article comprising the liquid crystal polyester resin according to any one of (1) to (4) or the liquid crystal polyester resin composition according to (6). (8) The molded article according to (7), wherein the molded article is any one selected from the group consisting of a connector, a relay, a switch, a coil bobbin, and an actuator part of a camera module. A molded article containing a liquid crystal polyester resin, which contains 20 to 80 mol% of a structural unit derived from an aromatic hydroxycarboxylic acid, 10 to 40 mol% of a structural unit derived from an aromatic diol, and 10 to 40 mol% of a structural unit derived from an aromatic dicarboxylic acid, and the aromatic hydroxycarboxylic acid contains at least 15 to 75 mol% of structural unit (I) and 2 to 20 mol% of structural unit (II). A molded article in which the phenol gas generated when the molded article is held at 280 ° C for 60 minutes under a reduced pressure of 13.3 kPa or less is 60 ppm or less.

Advantages of the Invention

[0016] The liquid crystal polyester resin of the present invention reduces metal corrosiveness in use under high temperature environments and is excellent in low warpage. The liquid crystal polyester resin of the present invention can be suitably used particularly when molding small electric and electronic component applications or when used in contact with metal parts such as terminals.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described in detail.

[0019] <Liquid Crystal Polyester Resin> The liquid crystal polyester resin is a polyester that forms an anisotropic molten phase. Examples of such a polyester resin include polyesters composed of structural units selected to form an anisotropic molten phase from, for example, an oxycarbonyl unit, a dioxy unit, a dicarbonyl unit, etc., which will be described later.

[0020] The liquid crystal polyester resin of the present invention is a liquid crystal polyester resin containing at least 15 to 75 mol% of structural unit (I) and 2 to 20 mol% of structural unit (II) as aromatic hydroxycarboxylic acids described later, and when held at the melting point + 20 °C for 60 minutes under a reduced pressure of 13.3 kPa (100 torr) or less, the phenol gas generated is 100 ppm or less. This means that less phenol gas is generated during melt processing. Hereinafter, when held at the temperature of the melting point Tm + 20 °C for 60 minutes under a reduced pressure of 13.3 kPa or less, the phenol gas generated from the liquid crystal polyester resin may be simply abbreviated as "phenol gas generation amount".

[0021] When structural unit (I) and structural unit (II) are used in combination as the structural units of the liquid crystal polyester resin, the crystallinity of the liquid crystal polyester resin can be controlled and high strength can be achieved. However, the monomer constituting structural unit (I) is likely to remain unreacted, and phenol gas is likely to be generated due to thermal denaturation. By setting the structural units constituting the liquid crystal polyester resin within the preferable ranges described later, or setting the production method of the liquid crystal polyester resin to the preferable modes described later, the monomer constituting structural unit (I) can be sufficiently incorporated into the polymer chain, thermal denaturation can be suppressed, and thus the phenol gas generation amount can be reduced. Such a liquid crystal polyester resin in which structural unit (I) and structural unit (II) are used in combination and the phenol gas generation amount is small can reduce the metal corrosiveness during use in a high-temperature environment. Furthermore, since less phenol gas is generated during melt processing, the phenol gas remaining in the molded product is reduced, and the phenol gas released when the molded product is further processed at a higher temperature is reduced, so the metal corrosiveness during the high-temperature processing of the molded product can also be reduced. In addition, the liquid crystal polyester resin of the present invention, in addition to being of high strength, is less likely to generate fine unfilled portions in the molded product due to generated gas even when molded under molding conditions where generated gas such as a low injection speed is likely to remain, and since deformation after heating can be reduced, it is excellent in low warpage property. Details of the structural units and production method constituting the liquid crystal polyester resin are described in the structural units constituting the following liquid crystal polyester resin and the "Production Method of Liquid Crystal Polyester Resin" described later.

[0022] If the amount of phenol gas generated is more than 100 ppm, the metal corrosivity during use in a high-temperature environment deteriorates, the warpage of the molded product becomes large, which is not preferable. Also, when made into a molded product, the amount of phenol gas generated when held at 280 °C increases, and the metal corrosivity deteriorates, which is not preferable. The amount of phenol gas generated is preferably 90 ppm or less, more preferably 80 ppm or less, still more preferably 70 ppm or less, and particularly preferably 60 ppm or less. The lower limit is 0 ppm.

[0023] Here, the melting point is the endothermic peak temperature (Tm 1 ) observed when the liquid crystal polyester resin is heated from room temperature under a temperature increase condition of 20 °C / min using a differential scanning calorimeter. After the observation of Tm 1 is held at a temperature of Tm + 20 °C for 5 minutes, once cooled to room temperature under a temperature decrease condition of 20 °C / min, and then heated again under a temperature increase condition of 20 °C / min, it refers to the endothermic peak temperature (Tm) observed.

[0024] The method for calculating the amount of phenol gas generated is shown below. First, 5 g of liquid crystal polyester resin pellets are dried at 150°C for 3 hours using a hot air dryer, and then placed in the heating part (A) of an ampoule glass tube having the shape shown in Fig. 1. Using a vacuum pump (DTC-22 manufactured by ULVAC), while controlling the degree of vacuum in the system to 13.3 kPa (100 torr) or less by performing vacuum suction from the tip of the ampoule glass tube, the part (B) 70 mm from the tip is heated and melted with a gas burner and sealed to produce an ampoule for analysis shown in Fig. 2. Next, the heating part (A) of the analysis ampoule is held at a temperature of the melting point of the liquid crystal polyester resin + 20°C for 60 minutes using a ceramic electric tubular furnace (ARF-30K manufactured by Asahi Rika Co., Ltd. (temperature controller AMF-N type)). The gas components generated from the liquid crystal polyester resin pellets by heating are collected at the part (C). After taking out the ampoule from the ceramic electric tubular furnace and cooling it to room temperature, the part (C) is cut out from the ampoule with a file. After weighing the cut-out part (C), all the gas components condensed in the part (C) are dissolved in deuterated dimethyl sulfoxide (0.8 g), and a small amount of 1,4-dioxane is added as an internal standard. The resulting solution is measured by 1 1H-NMR using a JNM-ECZ500R manufactured by JEOL Ltd. Also, the part (C) from which the collected components have been removed is washed with acetone, dried in a glass dryer at 60°C for 1 hour, and then weighed again. The total amount of generated gas is calculated from the difference in the weight of the part (C) before and after removal of the collected components. From the 1 1H-NMR spectrum obtained above, the integral value ratio of the peak derived from phenol and the peak of the internal standard (1,4-dioxane) is determined. From this and the total amount of generated gas, the amount of phenol gas (ppm) generated from the liquid crystal polyester resin is calculated.

[0025] Here, the degree of vacuum in the ampoule glass tube is not particularly limited as long as it is 13.3 kPa (100 torr) or less. For example, it may be a high vacuum state of 133 Pa (1 torr) or less. By setting the inside of the ampoule glass tube to a vacuum state, in addition to facilitating the generation of phenol gas from the liquid crystal polyester resin, phenol gas can be efficiently collected.

[0026] Next, the structural units constituting the liquid crystal polyester resin will be described.

[0027] The liquid crystal polyester resin of the present invention contains, as oxycarbonyl units, 20 to 80 mol% of structural units derived from aromatic hydroxycarboxylic acids with respect to 100 mol% of all the structural units of the liquid crystal polyester resin. If the content of the structural unit is less than 20 mol%, the liquid crystallinity is impaired and the warpage property deteriorates. The content of the structural unit is preferably 25 mol% or more, and more preferably 30 mol% or more. On the other hand, if the content of the structural unit is more than 80 mol%, it becomes difficult to control the phenol gas to 100 ppm or less, and the metal corrosivity and warpage property during use in a high-temperature environment deteriorate. The content of the structural unit is preferably 75 mol% or less, and more preferably 70 mol% or less.

[0028] The liquid crystal polyester resin of the present invention contains 15 to 75 mol% of structural unit (I) as the structural unit derived from aromatic hydroxycarboxylic acids. If the content of the structural unit is less than 15 mol%, the liquid crystallinity is impaired and the warpage property deteriorates. From the viewpoint of reducing the metal corrosivity during use in a high-temperature environment and being excellent in low warpage property, the content of the structural unit is more preferably 25 mol% or more, and further preferably 35 mol% or more. On the other hand, if the content of the structural unit is more than 75 mol%, it becomes difficult to control the phenol gas to 100 ppm or less, and the metal corrosivity and warpage property during use in a high-temperature environment deteriorate. From the viewpoint of reducing the metal corrosivity during use in a high-temperature environment and being excellent in low warpage property, the content of the structural unit is preferably 65 mol% or less, and more preferably 55 mol% or less.

[0029]

Chemical formula

[0030] The liquid crystal polyester resin of the present invention contains 2 to 20 mol% of structural unit (II) as a structural unit derived from an aromatic hydroxycarboxylic acid. Structural unit (II) is a structural unit derived from 6-hydroxy-2-naphthoic acid. When the content of this structural unit is less than 2 mol%, it becomes difficult to control the crystallinity of the liquid crystal polyester resin, and the warpage deteriorates. Further, when a production method is used in which the deacetic acid polymerization reaction at a temperature of 230 to 245 °C described later is controlled and the amount of phenol gas generated is controlled within a suitable range, the reaction of structural unit (I) is promoted, resulting in the formation of a high-crystalline structure, which affects the reactions of other structural units. Therefore, even if the amount of phenol gas generated is controlled to 100 ppm, the warpage deteriorates, and the metal corrosiveness during use in a high-temperature environment also deteriorates. From the viewpoint of reducing the metal corrosiveness during use in a high-temperature environment and being excellent in low warpage, the content of this structural unit is preferably 2.5 mol% or more, more preferably 3 mol% or more. On the other hand, when the content of this structural unit is more than 20 mol%, it becomes difficult to control the amount of phenol gas generated to 100 ppm or less, and the metal corrosiveness and warpage during use in a high-temperature environment deteriorate. From the viewpoint of reducing the metal corrosiveness during use in a high-temperature environment and being excellent in low warpage, the content of this structural unit is preferably 15 mol% or less, more preferably 10 mol% or less.

[0031]

Chemical formula

[0032] When the amount of phenol gas generated by the liquid crystal polyester resin of the present invention is controlled to 100 ppm or less, from the viewpoint of reducing metal corrosiveness in use under a high-temperature environment and excellent low warpage property, the content of structural unit (I) is preferably 80 mol% or more, more preferably 85 mol% or more, and even more preferably 90 mol% or more, based on a total of 100 mol% of structural unit (I) and structural unit (II). On the other hand, when the amount of phenol gas generated is controlled to 100 ppm or less, from the viewpoint of reducing metal corrosiveness in use under a high-temperature environment and excellent low warpage property, the content of structural unit (I) is preferably 97 mol% or less, more preferably 96 mol% or less, and even more preferably 95 mol% or less.

[0033] The liquid crystal polyester resin of the present invention may contain structural units other than the above structural units (I) and (II) as oxycarbonyl units. As specific examples of other oxycarbonyl units, structural units derived from m-hydroxybenzoic acid and the like can be used.

[0034] The liquid crystal polyester resin of the present invention contains, as dioxy units, 10 to 40 mol% of structural units derived from aromatic diols with respect to 100 mol% of all the structural units of the liquid crystal polyester resin. If the content of the structural units is less than 10 mol%, it becomes difficult to control the phenol gas generation amount to 100 ppm or less, and the metal corrosivity and warpage in use under a high-temperature environment deteriorate. The content of the structural units is preferably 15 mol% or more, more preferably 20 mol% or more. On the other hand, if the content of the structural units is more than 40 mol%, the liquid crystallinity is impaired and the warpage deteriorates. The content of the structural units is preferably 35 mol% or less, more preferably 30 mol% or less. Examples of the structural units derived from aromatic diols include structural units derived from, for example, 4,4'-dihydroxybiphenyl, hydroquinone, resorcinol, t-butylhydroquinone, phenylhydroquinone, chloro-hydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, and the like.

[0035] From the viewpoint that the liquid crystal polyester resin of the present invention can easily control the phenol gas generation amount to 100 ppm or less, can reduce the metal corrosivity in use under a high-temperature environment, and is excellent in low warpage, it is preferable to contain 2 mol% or more, preferably 5 mol% or more, and more preferably 8 mol% or more of the structural unit (III) as the structural unit derived from aromatic diols with respect to 100 mol% of all the structural units of the liquid crystal polyester resin. The structural unit (III) is a structural unit derived from hydroquinone. On the other hand, from the viewpoint that the phenol gas generation amount can be easily controlled to 100 ppm or less, the metal corrosivity in use under a high-temperature environment can be reduced, and it is excellent in low warpage, it is preferable to contain the structural unit (III) in an amount of 20 mol% or less, more preferably 18 mol% or less, and even more preferably 16 mol% or less.

[0036]

Chemical formula

[0037] In terms of easily controlling the phenol gas generation amount to 100 ppm or less, reducing the metal corrosiveness during use in a high-temperature environment, and being excellent in low warpage, it is preferable that, based on 100 mol% of all structural units of the liquid crystal polyester resin, the structural unit (IV) as a structural unit derived from an aromatic diol is contained in an amount of 2 mol% or more, preferably 4 mol% or more, and more preferably 6 mol% or more. The structural unit (IV) is a structural unit derived from 4,4'-dihydroxybiphenyl. On the other hand, in terms of easily controlling the phenol gas generation amount to 100 ppm or less, reducing the metal corrosiveness during use in a high-temperature environment, and being excellent in low warpage, it is preferable that the structural unit (III) is contained in an amount of 20 mol% or less, more preferably 17 mol% or less, and even more preferably 14 mol% or less.

[0038]

Chemical formula

[0039] In terms of easily controlling the phenol gas generation amount to 100 ppm or less, reducing the metal corrosiveness during use in a high-temperature environment, and being excellent in low warpage, it is preferable that, based on 100 mol% of the total of the structural unit (III) and the structural unit (IV), the content of the structural unit (III) is 45 mol% or more, more preferably 47 mol% or more, and even more preferably 50 mol% or more. On the other hand, in terms of easily controlling the phenol gas generation amount to 100 ppm or less, reducing the metal corrosiveness during use in a high-temperature environment, and being excellent in low warpage, it is preferable that the content of the structural unit (III) is 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less.

[0040] The liquid crystal polyester resin of the present invention may contain, as dioxy units, structural units other than the above structural units (III) and (IV). As other dioxy units, structural units derived from aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol; structural units derived from alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol can be used within a range that does not impair the effects of the present invention.

[0041] The liquid crystal polyester resin of the present invention contains, as dicarbonyl units, 10 to 40 mol% of structural units derived from aromatic dicarboxylic acids with respect to 100 mol% of all the structural units of the liquid crystal polyester resin. When the content of this structural unit is less than 10 mol%, it becomes difficult to control the phenol gas generation amount to 100 ppm or less, and the metal corrosiveness and warpage during use in a high-temperature environment deteriorate. The content of this structural unit is preferably 15 mol% or more, more preferably 20 mol% or more. On the other hand, when the content of this structural unit is more than 40 mol%, the liquid crystallinity is impaired and the warpage deteriorates. The content of this structural unit is preferably 35 mol% or less, more preferably 30 mol% or less. Examples of the structural units derived from aromatic dicarboxylic acids include structural units derived from terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 3,3'-diphenyldicarboxylic acid, 2,2'-diphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4'-dicarboxylic acid, 1,2-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, and the like.

[0042] The liquid crystal polyester resin of the present invention can easily control the phenol gas generation amount to 100 ppm or less, can reduce the metal corrosiveness in use under a high-temperature environment, and is excellent in low warpage. From this viewpoint, with respect to 100 mol% of all structural units of the liquid crystal polyester resin, as a structural unit derived from an aromatic dicarboxylic acid, it is preferable to contain 5 mol% or more of structural unit (V), more preferably 10 mol% or more, and even more preferably 15 mol% or more. Structural unit (V) is a structural unit derived from terephthalic acid. On the other hand, from the viewpoint of easily controlling the phenol gas generation amount to 100 ppm or less, reducing the metal corrosiveness in use under a high-temperature environment, and being excellent in low warpage, it is preferable to contain 35 mol% or less of structural unit (V), more preferably 30 mol% or less, and even more preferably 25 mol% or less.

[0043]

Chemical formula

[0044] The liquid crystal polyester resin of the present invention can easily control the phenol gas generation amount to 100 ppm or less, can reduce the metal corrosiveness in use under a high-temperature environment, and is excellent in low warpage. From this viewpoint, with respect to 100 mol% of all structural units of the liquid crystal polyester resin, as a structural unit derived from an aromatic diol, it is preferable to contain 0.01 mol% or more of structural unit (VI), more preferably 0.05 mol% or more, and even more preferably 0.1 mol% or more. Structural unit (VI) is a structural unit derived from isophthalic acid. On the other hand, from the viewpoint of easily controlling the phenol gas generation amount to 100 ppm or less, reducing the metal corrosiveness in use under a high-temperature environment, and being excellent in low warpage, it is preferable to contain 5 mol% or less of structural unit (VI), more preferably 4 mol% or less, and even more preferably 3 mol% or less.

[0045]

Chemical formula

[0046] The liquid crystal polyester resin of the present invention may contain, as the dicarbonyl unit, structural units other than the above structural units (V) and (VI). As other dicarbonyl units, structural units derived from aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hexahydroterephthalic acid; structural units derived from alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid and 1,3-cyclohexanedicarboxylic acid can be used within a range not impairing the effects of the present invention.

[0047] In addition to the above structural units (I) to (VI), the liquid crystal polyester resin may contain structural units derived from p-aminobenzoic acid, p-aminophenol, etc. within a range not impairing the effects of the present invention.

[0048] By including the above structural units (III) to (VI) within the above-mentioned range, the liquid crystal polyester resin of the present invention allows the structural unit (I) to be sufficiently incorporated into the polymer chain, suppressing thermal denaturation, and thus making it easier to control the phenol gas generation amount to 100 ppm or less.

[0049] Also, from the viewpoint of not impairing the effects of the present invention, it is preferable that the total amount of the above structural units (I) to (VI) is 99 mol% or more, more preferably 99.5 mol% or more, and still more preferably 100 mol% with respect to 100 mol% of all the structural units of the liquid crystal polyester resin.

[0050] In addition, from the viewpoint of polymerization control, the ratio ([III] + [IV]) / ([V] + [VI]) of the total amount of the structural unit (III) and the structural unit (IV) to the total amount of the structural unit (V) and the structural unit (VI) is preferably 0.9 or more and 1.1 or less.

[0051] The monomers serving as raw materials for the above respective structural units are not particularly limited as long as they have a structure capable of forming each structural unit. Further, derivatives such as acylates of the hydroxyl groups of such monomers, esters of carboxyl groups, acid halides, acid anhydrides, etc. may be used.

[0052] For liquid crystal polyester resins, the method for calculating the content of each structural unit is shown below. First, after pulverizing the liquid crystal polyester resin, add tetramethylammonium hydroxide and perform pyrolysis GC / MS measurement using a Shimadzu GCMS-QP5050A to determine the content of each structural unit. The content of structural units that were not detected or were below the detection limit is calculated as 0 mol%.

[0053] 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 and reducing the amount of phenol gas generated and the metal corrosiveness during use in a high-temperature environment, 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.

[0054] From the perspective of heat resistance and reducing the amount of phenol gas generated to reduce the metal corrosiveness during use in a high-temperature environment and excellent low warpage property, the melt viscosity of the liquid crystal polyester resin is preferably 1 Pa·s or higher, more preferably 3 Pa·s or higher, and even more preferably 5 Pa·s or higher. On the other hand, from the perspective of fluidity, the melt viscosity of the liquid crystal polyester resin is preferably 50 Pa·s or lower, more preferably 20 Pa·s or lower, even more preferably 15 Pa·s or lower, and particularly preferably 10 Pa·s or lower.

[0055] This melt viscosity is a value measured by a Koka-type flow tester at a temperature of the melting point (Tm) of the liquid crystal polyester resin + 20 °C and under the condition of a shear rate of 1000 / second.

[0056] <Method for producing liquid crystal polyester resin> The method for producing the liquid crystal polyester resin of the present invention includes a method of copolymerizing monomers that provide structural units (I) to (VI) in the above-described content ranges, or blending two or more liquid crystal polyester resins obtained by copolymerizing structural units (I) to (VI) in content ranges outside the above-described ranges so that the structural units (I) to (VI) are within the above-described ranges. From the viewpoint of not inheriting the properties of the liquid crystal polyester resin before blending, a method of copolymerizing monomers that provide structural units (I) to (VI) in the above-described content ranges is preferred.

[0057] The method for producing the liquid crystal polyester resin of the present invention is not particularly limited and can be produced according to a known polycondensation method for polyesters. From the viewpoint of reducing the amount of phenol gas generated, reducing the metal corrosiveness during use in a high-temperature environment, and being excellent in low warpage, taking a liquid crystal polyester resin composed of a structural unit derived from p-hydroxybenzoic acid, a structural unit derived from 6-hydroxy-2-naphthoic acid, a structural unit derived from 4,4'-dihydroxybiphenyl, a structural unit derived from hydroquinone, and structural units derived from terephthalic acid and isophthalic acid as an example, acetic anhydride is reacted with p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, terephthalic acid, and isophthalic acid to acetylate at least a part of the phenolic hydroxyl groups, and then deacetylation polymerization is carried out to produce a liquid crystal polyester resin.

[0058] Furthermore, in the above-described production method, by satisfying the following requirements, the amount of phenol gas generated can be controlled within a suitable range. It is preferable to satisfy the following requirement 1, and more preferable to satisfy both requirements 1 and 2. 1. The deacetylation polymerization reaction at a temperature of 230 to 245 °C is carried out for 40 to 120 minutes. 2. When increasing the degree of polymerization of the liquid crystal polyester resin, the reaction is carried out under reduced pressure, and the reaction is completed at a reduced pressure of 4.0 kPa (30 torr) or less.

[0059] Regarding the requirement 1 above, the temperature range of 230 to 245 °C is a temperature range in which the deacylation polymerization of p-hydroxybenzoic acid constituting the structural unit (I) and 6-hydroxy-2-naphthoic acid constituting the structural unit (II) is promoted. In this temperature range, by sufficiently performing the deacylation polymerization reaction, p-hydroxybenzoic acid can be sufficiently incorporated into the polymer chain before it sublimes and becomes unreactive, so that the thermal denaturation of unreacted p-hydroxybenzoic acid and the generation of phenol gas can be suppressed. Further, by using p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid in combination, only the reaction of p-hydroxybenzoic acid can be promoted, and the formation of a high crystal structure can be suppressed. The time for the deacylation polymerization reaction at a temperature of 230 to 245 °C is preferably 50 minutes or more, more preferably 60 minutes or more. On the other hand, it is more preferably 110 minutes or less, and even more preferably 100 minutes or less.

[0060] Regarding the requirement 2 above, when unreacted p-hydroxybenzoic acid remains, the generation of phenol gas can be suppressed by removing it outside the polymer system by decompression during the polymerization reaction. The degree of decompression is preferably 2.7 kPa (20 torr) or less, and more preferably 1.3 kPa (10 torr) or less.

[0061] <Filler> The liquid crystal polyester resin of the present invention may be a liquid crystal polyester resin composition containing a filler in order to impart mechanical strength and other properties to the liquid crystal polyester resin. The filler used in the present invention is not particularly limited, and examples thereof include fillers in the form of fibers, whiskers, plates, powders, granules, and the like. Specifically, examples of the fibrous or whisker-like filler include glass fiber, PAN-based and pitch-based carbon fibers, metal fibers such as stainless steel fiber, aluminum fiber, and brass fiber, organic fibers such as aromatic polyamide fiber and liquid crystal polyester fiber, gypsum fiber, ceramic fiber, asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker, and acicular titanium oxide. Examples of the plate-like filler include mica, talc, kaolin, glass flake, clay, molybdenum disulfide, and wollastonite. Examples of the powdery or granular filler include silica, glass beads, titanium oxide, zinc oxide, calcium polyphosphate, and graphite. The surface of the above-mentioned filler used in the present invention may be treated with a known coupling agent (for example, a silane-based coupling agent, a titanate-based coupling agent, etc.) or other surface treatment agents. Further, two or more of the above-mentioned fillers used in the present invention may be used in combination.

[0062] Among the above fillers, it is preferable to use glass fiber because of 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 generally used for reinforcing resins, and examples thereof include chopped strands of long fiber type and short fiber type, and milled fiber. Further, it is preferable to use a plate-like filler because of its excellent thin-wall fluidity and low warpage, and mica is more preferable among them.

[0063] The surface of the above-mentioned filler may be treated with a known coupling agent (e.g., silane-based coupling agent, titanate-based coupling agent, etc.) or other surface treatment agents. Also, the glass fiber may be coated or aggregated with a thermoplastic resin such as ethylene / vinyl acetate copolymer or a thermosetting resin such as epoxy resin.

[0064] In the liquid crystal polyester resin composition of the present invention, antioxidants, heat stabilizers (e.g., hindered phenols, hydroquinones, phosphites, thioethers and their substituents, etc.), ultraviolet absorbers (e.g., resorcinol, salicylate), phosphites, hypophosphites and other anti-coloring agents, lubricants and mold release agents (montanic acid and its metal salts, its esters, its half esters, stearyl alcohol, stearamide and polyethylene wax, etc.), coloring agents containing dyes or pigments, conductive agents or carbon black as a coloring agent, crystal nucleating agents, plasticizers, flame retardants (bromine-based flame retardants, phosphorus-based flame retardants, red phosphorus, silicone-based flame retardants, etc.), flame retardant aids, and antistatic agents can be blended within a range that does not impair the effects of the present invention.

[0065] In the liquid crystal polyester resin composition of the present invention, the content of the filler is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the liquid crystal polyester resin. If the content of the filler is 10 parts by weight or more, the mechanical strength of the molded article can be improved. The content of the filler is more preferably 15 parts by weight or more, and even more preferably 20 parts by weight or more. On the other hand, if the content of the filler is 200 parts by weight or less, a liquid crystal polyester resin composition excellent in moldability and thin-wall fluidity, capable of easily injection molding small and thin-wall molded articles, is obtained, which is preferable. The content of the filler is more preferably 150 parts by weight or less, and even more preferably 100 parts by weight or less.

[0066] As methods for blending the above-mentioned filler and additives, for example, a dry blending method in which a filler and other solid additives are blended into a liquid crystal polyester resin, a solution blending method in which a filler and other liquid additives are blended into a liquid crystal polyester resin, a method of adding a filler and other additives during the polymerization of a liquid crystal polyester resin, and a method of melt-kneading a liquid crystal polyester resin, a filler, and other additives can be used. Among them, the method of melt-kneading is preferred.

[0067] For melt-kneading, known methods can be used. For example, a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder, etc. can be mentioned. Among them, a twin-screw extruder is preferred. The melt-kneading temperature is preferably not less than the melting point of the liquid crystal polyester resin and not more than the melting point + 50°C.

[0068] As kneading methods, 1) a method of charging a liquid crystal polyester resin, a filler, and other additives all at once from a hopper and kneading them (one-shot kneading method), 2) a method of charging a liquid crystal polyester resin and other additives from a hopper, kneading them, and then adding a filler and other additives from a side feeder and kneading them (side feed method), 3) a method of producing a liquid crystal polyester composition (master pellet) containing a liquid crystal polyester resin and other additives at a high concentration, and then kneading the master pellet with a liquid crystal polyester resin and a filler so as to reach a specified concentration (master pellet method), etc. can be mentioned.

[0069] <Molded article> The liquid crystal polyester resin and the 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 by molding methods such as ordinary injection molding, extrusion molding, press molding, solution cast film formation, and spinning. Examples of the molded articles herein include injection molded articles, extrusion molded articles, press molded articles, sheets, pipes, unstretched films, uniaxially stretched films, biaxially stretched films, and other various films, unstretched yarns, super stretched yarns, and other various fibers. Particularly from the viewpoint of processability, an injection molded article is preferred. When melt molding, from the viewpoints of suppressing deterioration of the liquid crystal polyester resin and the liquid crystal polyester resin composition, suppressing the phenol gas generated when the molded article described later is held at 280°C, suppressing metal corrosiveness, and improving mechanical strength, it is preferably melt molded at 370°C or lower, more preferably 360°C or lower.

[0070] The molded article of the present invention contains 20 to 80 mol% of a structural unit derived from an aromatic hydroxycarboxylic acid, 10 to 40 mol% of a structural unit derived from an aromatic diol, and 10 to 40 mol% of a structural unit derived from an aromatic dicarboxylic acid. As the aromatic hydroxycarboxylic acid, it contains at least 15 to 75 mol% of the structural unit (I) and 2 to 20 mol% of the structural unit (II). It is a molded article containing a liquid crystal polyester resin, and when held at 280°C for 60 minutes under a reduced pressure of 13.3 kPa or less, the generated phenol gas is 60 ppm or less. 280°C is a temperature close to the temperature when the molded article is secondary processed such as reflow treatment. It indicates that phenol gas is hardly released when the molded article is secondary processed and has excellent processability.

[0071] By using a liquid crystal polyester resin having a phenol gas generation amount of 100 ppm or less as shown in the above liquid crystal polyester resin section, the phenol gas generated during melt processing such as melt kneading and injection molding is reduced, the phenol gas remaining in the molded article is reduced, and the phenol gas generated when held at 280°C can be made 60 ppm or less. Such a molded article can reduce the metal corrosiveness during processing at a high temperature.

[0072] On the other hand, when using a liquid crystal polyester resin with a phenol gas generation amount of more than 100 ppm, the phenol gas generated during melt processing increases, and the phenol gas remaining in the molded product also increases. Therefore, the phenol gas generated when held at 280 °C becomes more than 60 ppm. Such molded products have deteriorated metal corrosiveness when processed at high temperatures.

[0073] Regarding the amount of phenol gas generated when the molded product is held at 280 °C, from the viewpoint of reducing metal corrosiveness in use under high-temperature environments, 50 ppm or less is preferable, and 40 ppm or less is more preferable.

[0074] Note that the method for measuring the amount of phenol gas generated from the molded product is measured in the same manner as the method described in the liquid crystal polyester resin section, except that the temperature of the ceramic electric tube furnace is set to 280 °C. In the case of a liquid crystal polyester resin composition containing a filler, it is calculated by converting to the amount of gas generated from the liquid crystal polyester resin excluding the filler.

[0075] The molded products obtained by molding the liquid crystal polyester resin and the liquid crystal polyester resin composition of the present invention can be preferably used as electrical and electronic components. Examples of electrical and electronic components include flexible printed circuit boards, laminated circuit boards, printed wiring boards, and three-dimensional circuit boards used for antennas of mobile communication and electronic devices such as personal computers, GPS-equipped devices, mobile phones, millimeter-wave and quasi-millimeter-wave radars such as collision prevention radars, tablets, and smartphones; lamp reflectors and lamp sockets such as LEDs, communication base station small cells and microcell members of mobile communication terminals, antenna covers, housings, sensors, actuator parts of camera modules, connectors, relay cases and bases, switches, coil bobbins, capacitors, etc. Among them, from the viewpoint of reducing metal corrosiveness in use under high-temperature environments and excellent low warpage properties, it is useful for connectors, relays, switches, coil bobbins, actuator parts of camera modules, etc. that are used in contact with metal parts and have thin and complex-shaped parts.

Examples

[0076] Hereinafter, the present invention will be described using examples, but the present invention is not limited by the examples. In the examples, the composition and property evaluation of the liquid crystal polyester resin were measured by the following methods. Note that Examples 9-11 are currently reference examples, and Examples 1-8 and 12 are the examples of the present invention.

[0077] (1) Composition analysis of liquid crystal polyester resin To 0.1 mg of the pulverized liquid crystal polyester resin pellets, 2 μL of a 25% methanol solution of tetramethylammonium hydroxide was added, and pyrolysis GC / MS measurement was performed using a Shimadzu GCMS-QP5050A to determine the content ratio of each structural unit in the liquid crystal polyester resin.

[0078] (2) Measurement of melting point (Tm) of liquid crystal polyester resin Using a differential scanning calorimeter DSC-7 (manufactured by PerkinElmer), when the liquid crystal polyester resin was heated from room temperature under a temperature increase condition of 20 °C / min, the endothermic peak temperature (Tm 1 ) was observed. After the observation of Tm 1 was held at a temperature of Tm + 20 °C for 5 minutes, it was once cooled to room temperature under a temperature decrease condition of 20 °C / min, and the endothermic peak temperature observed when it was heated again under a temperature increase condition of 20 °C / min was defined as the melting point (Tm).

[0079] (3) Melt viscosity of liquid crystal polyester resin Using a Koka-type flow tester CFT-500D (orifice 0.5φ × 10 mm) (manufactured by Shimadzu Corporation), the melt viscosity of the liquid crystal polyester resin was measured at Tm + 20 °C under the condition of a shear rate of 1000 / s.

[0080] (4) Amount of phenol gas generated 5 g of liquid crystal polyester resin pellets were dried at 150 °C for 3 hours using a hot air dryer, and then placed in the heating part (A) of an ampoule glass tube having the shape shown in Fig. 1. Using a vacuum pump (DTC-22 manufactured by ULVAC), while controlling the degree of vacuum in the system to 133 Pa (1 torr) by performing vacuum suction from the tip of the ampoule glass tube, the part (B) 70 mm from the tip was heated and melted with a gas burner to seal the tube, and an ampoule for analysis shown in Fig. 2 was produced. Next, the heating part (A) of the analysis ampoule was held at a temperature 20 °C higher than the melting point of the liquid crystal polyester resin for 60 minutes using a ceramic electric tubular furnace (ARF-30K (temperature controller AMF-N type) manufactured by Asahi Rika Seisakusho), and the generated gas was collected at the part (C). After taking out the ampoule from the ceramic electric tubular furnace and cooling it to room temperature, the part (C) was cut out from the ampoule with a file. After weighing the cut-out part (C), all the gas components aggregated at the part (C) were dissolved in deuterated dimethyl sulfoxide (0.8 g), and a small amount of 1,4-dioxane was added as an internal standard. The obtained solution was subjected to 1 1H-NMR measurement using JNM-ECZ500R manufactured by JEOL Ltd. Further, the part (C) from which the collected components were removed was washed with acetone, dried in a glass dryer at 60 °C for 1 hour, and then weighed again. The total amount of the generated gas was calculated from the difference in the weight of the part (C) before and after the removal of the collected components. From the 1 1H-NMR spectrum obtained above, the integral value ratio of the peak derived from phenol and the peak of the internal standard (1,4-dioxane) was determined. From this and the total amount of the generated gas, the amount of phenol gas (ppm) generated from the liquid crystal polyester resin was calculated.

[0081] (5) Metal corrosivity 30 g of liquid crystal polyester resin pellets were dried at 150 °C for 3 hours using a hot air dryer, then placed in an aluminum cup. A copper plate with a size of 20 mm × 10 mm × 1 mm thick was placed on the pellets, and the cup was covered with a glass petri dish. Next, heat treatment was carried out at 150 °C for 200 hours or at 200 °C for 6 hours using a hot air dryer. The presence or absence of the metallic luster of the copper plate and the presence or absence of discoloration to dark brown or blackish brown were visually confirmed, and it was considered excellent in metal corrosion resistance in the order of A, B, C, D below. It was assumed that the lower the metal corrosivity in use under high-temperature environments, the more excellent the metal corrosion resistance at 200 °C for 6 hours of heat treatment.

[0082] A: With metallic luster, no discoloration B: Without metallic luster, no discoloration C: Without metallic luster, with dark brown, without blackish brown D: Without metallic luster, with dark brown, with blackish brown (6) Warpage The liquid crystal polyester resin was dried at 150 °C for 3 hours using a hot air dryer, and then fed into a Fanuc α30C injection molding machine (manufactured by Fanuc) to obtain a connector molded product shown in Fig. 3a, with a terminal pitch 6 of 0.4 mm, a minimum wall thickness 7 (partition wall part) of the product of 0.2 mm, and an outer dimension of width 5 of 3 mm × height 4 of 2 mm × length 3 of 30 mm. The cylinder temperature was set at the melting point of the liquid crystal polyester resin +10 °C, the mold temperature was 90 °C, the injection pressure was set at the minimum filling pressure, and the injection speed was set at 50, 100 mm / s. The liquid crystal polyester resin was filled from the pin gate G1 (gate diameter 0.3 mm) installed on the short side surface 2 on one side of the connector molded product shown in Fig. 3a. The obtained connector molded product was left in an oven heated to 260 °C for 3 minutes, and the warpage amount of the connector molded product after heat treatment was measured. Fig. 3b is a conceptual diagram showing the measurement site of the warpage amount in the above molded product. Using the A - B plane connecting both ends of the long side surface 1 of the molded product with a straight line as the reference plane a, the distance between the reference plane a and the maximum deformation plane b was measured and taken as the warpage amount 8. The lower the warpage amount, the more excellent the low warpage property.

[0083] (7) Phenol gas amount of the molded product Weighed 5 g of the connector molded product formed in (6), and calculated the amount of phenol gas (ppm) generated from the molded product by the same method as in (4), except that the heat treatment temperature in the ceramic electric tube furnace was 280°C.

[0084] (8) Metal corrosivity of the molded product Weighed 30 g of the connector molded product formed in (6), and evaluated the metal corrosivity of the molded product by the same method as in (5), except that the heat treatment was carried out at 280°C for 1 hour.

[0085] [Example 1] Charged 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 the total phenolic hydroxyl groups) into a 5 L reaction vessel equipped with a stirring blade and a distillation tube, and reacted at 145°C for 120 minutes while stirring in a nitrogen gas atmosphere, and then heated from 145°C to 360°C over 320 minutes. At this time, the temperature increase was controlled so that the reaction time from 230°C to 245°C was 95 minutes. Then, the polymerization temperature was maintained at 360°C, and the pressure was reduced to 1.0 torr (133 Pa) over 1.0 hour. The reaction was further continued, and polymerization was completed when a predetermined stirring torque was reached. Next, the polymer was discharged in a strand shape through a die having one circular discharge port with a diameter of 6 mm, and pelletized by a cutter to obtain a liquid crystal polyester resin (A-1).

[0086] [Example 2] A liquid crystal polyester resin (A-2) was obtained in the same manner as in Example 1, except that the temperature increase time from 145°C to 360°C was 295 minutes, and the temperature increase was controlled so that the reaction time from 230°C to 245°C was 70 minutes.

[0087] [Example 3] Polymerization was carried out in the same manner as in Example 1 except that the charged amount of acetic anhydride was 1314 parts by weight (1.10 equivalents based on the total phenolic hydroxyl groups). Since a predetermined stirring torque was reached at a reduced pressure of 3.0 kPa (23 torr), the polymerization was completed to obtain a liquid crystal polyester resin (A-3).

[0088] [Example 4] A liquid crystal polyester resin (A-4) was obtained in the same manner as in Example 1 except that the temperature rising time from 145°C to 360°C was 270 minutes and the temperature rising was controlled so that the reaction time from 230°C to 245°C was 45 minutes.

[0089] [Example 5] A liquid crystal polyester resin (A-5) was obtained in the same manner as in Example 1 except that the temperature rising time from 145°C to 360°C was 340 minutes and the temperature rising was controlled so that the reaction time from 230°C to 245°C was 115 minutes.

[0090] [Example 6] A liquid crystal polyester resin (A-6) was obtained in the same manner as in Example 1 except that the charged amounts of the monomers 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.

[0091] [Example 7] A liquid crystal polyester resin (A-7) was obtained in the same manner as in Example 1 except that the charged amounts of the monomers 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.

[0092] [Example 8] A liquid crystal polyester resin (A-8) was obtained in the same manner as in Example 1 except that the charged amounts of the monomers 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 9] The liquid crystal polyester resin (A-9) was obtained in the same manner as in Example 1, except that the charged amounts of the monomers 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.

[0094] [Example 10] The liquid crystal polyester resin (A-10) was obtained in the same manner as in Example 1, except that the charged amounts of the monomers 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.

[0095] [Example 11] Polymerization was carried out in the same manner as in Example 1, except that the charged amount of acetic anhydride was 1338 parts by weight (1.12 equivalents of the total phenolic hydroxyl groups). Since the predetermined stirring torque was reached at a reduced pressure of 45 torr, the polymerization was completed to obtain the liquid crystal polyester resin (A-11).

[0096] Table 1 and Table 2 show the results of the evaluations (1) to (6) for the liquid crystal polyester resins obtained in Examples 1 to 11 and Comparative Examples 1 to 3.

[0097] [Comparative Example 1] The liquid crystal polyester resin (A'-12) was obtained in the same manner as in Example 1, except that the charged amounts of the monomers 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, the temperature rising time from 145 °C to 360 °C was 240 minutes, and the reaction time from 230 °C to 245 °C was 15 minutes.

[0098] [Comparative Example 2] The liquid crystal polyester resin (A'-13) was obtained in the same manner as in Example 1, except that the charged amounts of the monomers 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.

[0099] [Comparative Example 3] The temperature increase time from 145°C to 360°C was set to 250 minutes, and the temperature increase was controlled so that the reaction time from 230°C to 245°C was 25 minutes. Otherwise, in the same manner as in Example 1, a liquid crystal polyester resin (A'-14) was obtained.

[0100]

Table 1

[0101]

Table 2

[0102] For the liquid crystal polyester resins obtained in Example 1 and Comparative Example 3, a filler was further added to prepare a liquid crystal polyester resin composition. The fillers used in each example and comparative example are shown below.

[0103] Filler (B) (B-1) Milled fiber (40M-10A) manufactured by Nippon Electric Glass [Example 12, Comparative Example 4] Using a Toshiba Machine TEM35B type twin-screw extruder equipped with a side feeder, the liquid crystal polyester resins (A-1, A'-14) obtained in each production example were charged from the hopper in the blending amounts shown in Table 2, and the filler (B-1) was charged from the side feeder in the blending amounts shown in Table 2. 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. After the pellets of the obtained liquid crystal polyester resin composition were dried by hot air, the evaluation results were the same as in (5) to (8) and are shown in Table 2. In the evaluation of (7), it was calculated by converting to the amount of gas generated from the liquid crystal polyester resin excluding the filler.

[0104]

Table 3

[0105] From the results of Tables 1 to 3, by using a liquid crystal polyester resin containing 15 to 75 mol% of structural unit (I) and 2 to 20 mol% of structural unit (II) and having a phenol gas content of 100 ppm or less, or a liquid crystal polyester resin composition using such a resin, it is possible to reduce the metal corrosiveness during use in a high-temperature environment and obtain a molded product with excellent low warpage property. Further, when the obtained molded product is held at 280 °C, the phenol gas is 70 ppm or less, and the metal corrosiveness during processing at high temperature can be reduced.

Industrial Applicability

[0106] The liquid crystal polyester resin and the liquid crystal polyester resin composition of the present invention can reduce the metal corrosiveness during use in a high-temperature environment and are excellent in low warpage property, and thus are suitable for applications such as electrical and electronic parts and mechanical parts such as connectors, relays, switches, coil bobbins, and actuator parts of camera modules.

Explanation of Symbols

[0107] (A) Pellet encapsulation and heating part (B) Sealing part of the tube (C) Generated gas collection part (D) Liquid crystal polyester resin pellet 1 Long side 2 Short side 3 Length 4 Height 5 Width 6 Pitch between terminals 7 Minimum wall thickness part 8 Warpage amount G1 Pin gate a Reference plane b Maximum deformation plane

Claims

1. The liquid crystal polyester resin contains 20 to 80 mol % of structural units derived from aromatic hydroxycarboxylic acid, 10 to 40 mol % of structural units derived from aromatic diol, and 10 to 40 mol % of structural units derived from aromatic dicarboxylic acid, relative to 100 mol % of all structural units of the liquid crystal polyester resin; A liquid crystal polyester resin containing, as the aromatic hydroxycarboxylic acid, at least 15 to 75 mol % of a structural unit (I), 2 to 20 mol % of a structural unit (II), and 5 to 25 mol % of a structural unit (V) as a structural unit derived from the aromatic dicarboxylic acid, wherein the amount of phenol gas generated when the resin is held at a melting point +20°C for 60 minutes under a reduced pressure of 13.3 kPa or less is 90 ppm or less; The melting point of the liquid crystal polyester resin is the endothermic peak temperature (Tm １ ) after the observation of Tm １ This is the endothermic peak temperature observed when the sample is held at +20° C. for 5 minutes, cooled to room temperature at a temperature drop rate of 20° C. / min, and then heated again at a temperature rise rate of 20° C. / min. 【Chemistry 1】

2. 2. The liquid crystal polyester resin according to claim 1, wherein the content of the structural unit (I) is 80 to 97 mol % relative to 100 mol % in total of the structural units (I) and (II).

3. 2. The liquid crystal polyester resin according to claim 1, wherein the aromatic diol contains 2 to 20 mol % of the structural unit (III) relative to 100 mol % of all structural units of the liquid crystal polyester resin. 【Chemistry 2】

4. The aromatic diol contains structural units (III) and (IV), and the content of the structural unit (III) is 45 to 90 mol% relative to the total of 100 mol% of the structural units (III) and (IV). The liquid crystal polyester resin according to claim 1. 【Chemistry 3】

5. A method for producing a liquid crystal polyester resin, comprising reacting a hydroxycarboxylic acid and / or a diol with acetic anhydride, acetylating at least a portion of a phenolic hydroxyl group, and then polymerizing the resulting mixture with a dicarboxylic acid to deacetylate, the method comprising carrying out the deacetylation polymerization reaction at a temperature of 230 to 245° C. for 40 to 120 minutes, comprising:

6. A method for producing a liquid crystal polyester resin as described in claim 5, wherein when increasing the degree of polymerization of the liquid crystal polyester resin, the reaction is carried out under reduced pressure and the reaction is completed at a reduced pressure of 4.0 kPa (30 torr) or less.

7. A liquid crystal polyester resin composition comprising 10 to 200 parts by weight of a filler based on 100 parts by weight of the liquid crystal polyester resin according to any one of claims 1 to 4.

8. A molded article comprising the liquid crystal polyester resin according to any one of claims 1 to 4 or the liquid crystal polyester resin composition according to claim 7.

9. 9. The molded article according to claim 8, which is any one selected from the group consisting of a connector, a relay, a switch, a coil bobbin, and an actuator part of a camera module.

10. A molded article comprising a liquid crystal polyester resin containing 20 to 80 mol % of a structural unit derived from an aromatic hydroxycarboxylic acid, 10 to 40 mol % of a structural unit derived from an aromatic diol, and 10 to 40 mol % of a structural unit derived from an aromatic dicarboxylic acid, the aromatic hydroxycarboxylic acid containing at least a structural unit (I) of 15 to 75 mol % and a structural unit (II) of 2 to 20 mol % and the aromatic dicarboxylic acid containing a structural unit (V) of 5 to 25 mol %, A molded article, the amount of phenol gas generated when the molded article is held at 280°C for 60 minutes under a reduced pressure of 13.3 kPa or less, is 50 ppm or less. 【Chemistry 4】

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