JP7578507B2 - Liquid crystal polyester amide resin - Google Patents

Description

The present invention relates to a liquid crystal polyester amide resin with excellent mechanical strength.

Liquid crystal polymers are widely used as high-performance engineering plastics because they have a good balance of excellent fluidity, mechanical strength, heat resistance, chemical resistance, electrical properties, etc. Known examples of liquid crystal polymers include liquid crystal polyesters and liquid crystal polyester amides.

As a liquid crystal polyesteramide, for example, Patent Document 1 proposes a wholly aromatic polyesteramide that is composed of specific repeating units and is said to have a sufficient balance between a low melting point and heat resistance.

JP 2020-41012 A

However, the wholly aromatic polyesteramide described in Patent Document 1 has poor mechanical properties such as tensile strength and impact resistance, making it difficult to use for parts of electronic devices such as mobile phones that are susceptible to shocks from being dropped during daily use.

The object of the present invention is to provide a liquid crystal polyesteramide resin that has excellent mechanical properties such as tensile strength and Izod impact strength.

In view of the above problems, the inventors conducted intensive research and discovered that liquid crystal polyesteramide resins composed of specific repeating units have excellent mechanical properties such as tensile strength and Izod impact strength, leading to the completion of the present invention.

［式中、ｐ、ｑ、ｒ、ｓおよびｔは、それぞれ、液晶ポリエステルアミド樹脂中での各繰返し単位の組成比（モル％）を示し、以下の式を満たす：
２５≦ｐ≦６０、
３≦ｑ≦５０、
５≦ｒ≦３０、
５≦ｓ≦２５、および
０≦ｔ≦２５］
で表される繰返し単位を含む、液晶ポリエステルアミド樹脂。
〔２〕 さらにｐ＋ｑ≧５０を満たす、〔１〕に記載の液晶ポリエステルアミド樹脂。
〔３〕 さらにｐ＋ｑ＋ｒ＋ｓ＋ｔ＝１００を満たす、〔１〕または〔２〕に記載の液晶ポリエステルアミド樹脂。
〔４〕 引張強度が１９０ＭＰａ以上である、〔１〕～〔３〕のいずれかに記載の液晶ポリエステルアミド樹脂。
〔５〕 ＡＳＴＭ Ｄ２５６に準拠したＩｚｏｄ衝撃強度が３００Ｊ／ｍ以上である、〔１〕～〔４〕のいずれかに記載の液晶ポリエステルアミド樹脂。
〔６〕 〔１〕～〔５〕のいずれかに記載の液晶ポリエステルアミド樹脂１００質量部に対し、繊維状、板状または粒状の充填剤０．１～２００質量部を含む、液晶ポリエステルアミド樹脂組成物。
〔７〕 〔１〕～〔５〕のいずれかに記載の液晶ポリエステルアミド樹脂あるいは〔６〕に記載の液晶ポリエステルアミド樹脂組成物から構成される成形品。 That is, the present invention includes the following preferred embodiments.
[1] Formulas (I) to (V)

[In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester amide resin, and satisfy the following formula:
25≦p≦60,
3≦q≦50,
5≦r≦30,
5≦s≦25, and 0≦t≦25]
A liquid crystal polyester amide resin comprising a repeating unit represented by the formula:
[2] The liquid crystal polyesteramide resin according to [1], further satisfying p+q≧50.
[3] The liquid crystal polyesteramide resin according to [1] or [2], further satisfying p+q+r+s+t=100.
[4] The liquid crystal polyesteramide resin according to any one of [1] to [3], having a tensile strength of 190 MPa or more.
[5] The liquid crystal polyesteramide resin according to any one of [1] to [4], having an Izod impact strength according to ASTM D256 of 300 J/m or more.
[6] A liquid crystal polyesteramide resin composition comprising 0.1 to 200 parts by mass of a fibrous, plate-like or granular filler per 100 parts by mass of the liquid crystal polyesteramide resin according to any one of [1] to [5].
[7] A molded article made of the liquid crystal polyesteramide resin according to any one of [1] to [5] or the liquid crystal polyesteramide resin composition according to [6].

The liquid crystal polyesteramide resin and liquid crystal polyesteramide resin composition of the present invention have excellent mechanical properties such as tensile strength and Izod impact strength, and are therefore suitable for use in electrical and electronic components such as housings and packages for various communication equipment and electronic devices.

In this specification and claims, "liquid crystal polyesteramide resin" refers to a polyesteramide resin that forms an anisotropic molten phase, and is known in the art as a thermotropic liquid crystal polyesteramide resin.

The nature of the anisotropic molten phase can be confirmed by conventional polarized light examination using crossed polarizers. More specifically, the anisotropic molten phase can be confirmed by observing the sample on a Leitz hot stage under a nitrogen atmosphere at 40x magnification using a Leitz polarizing microscope. The liquid crystal polyesteramide resin of the present invention is optically anisotropic, i.e., it transmits light when examined between crossed polarizers. If the sample is optically anisotropic, polarized light will be transmitted even when it is stationary.

The liquid crystal polyesteramide resin of the present invention contains aromatic oxycarbonyl repeating units represented by formula (I) and formula (II) as repeating units.

In the liquid crystal polyesteramide resin of the present invention, the composition ratio p of the repeating unit represented by formula (I) to the liquid crystal polyesteramide resin is 25 to 60 mol%, preferably 30 to 55 mol%. The composition ratio q of the repeating unit represented by formula (II) to the liquid crystal polyesteramide resin is 3 to 50 mol%, preferably 4 to 40 mol%, more preferably 5 to 35 mol%.

In the liquid crystal polyesteramide resin of the present invention, the repeating units represented by formula (I) and formula (II) preferably satisfy the relationship p+q≧50, more preferably satisfy the relationship p+q≧55, even more preferably satisfy the relationship p+q≧60, and particularly preferably satisfy the relationship p+q≧65.

Specific examples of monomers that give the repeating unit represented by formula (I) include, for example, 4-hydroxybenzoic acid and its acylated products, ester derivatives, acid halides, and other ester-forming derivatives.

Specific examples of monomers that give the repeating unit represented by formula (II) include 6-hydroxy-2-naphthoic acid and its acylated products, ester derivatives, acid halides, and other ester-forming derivatives.

The liquid crystal polyesteramide resin of the present invention also contains an aromatic oxyamino repeating unit represented by formula (III).

In the liquid crystal polyesteramide resin of the present invention, the composition ratio r of the repeating unit represented by formula (III) to the liquid crystal polyesteramide resin is 5 to 30 mol%, preferably 7 to 28 mol%, and more preferably 10 to 25 mol%.

Specific examples of monomers that provide the repeating unit represented by formula (III) include, for example, 4-aminophenol and its acylated and other amide-forming derivatives.

The liquid crystal polyesteramide resin of the present invention also contains an aromatic dicarbonyl repeating unit represented by formula (IV).

In the liquid crystal polyesteramide resin of the present invention, the composition ratio s of the repeating unit represented by formula (IV) to the liquid crystal polyesteramide resin is 3 to 25 mol %, preferably 5 to 23 mol %.

Specific examples of monomers that provide the repeating unit represented by formula (IV) include 2,6-naphthalenedicarboxylic acid, as well as its ester derivatives and ester-forming derivatives such as acid halides.

The liquid crystal polyesteramide resin of the present invention may further contain a repeating unit represented by formula (V) as another aromatic dicarbonyl repeating unit.

In the liquid crystal polyesteramide resin of the present invention, the composition ratio t of the repeating unit represented by formula (V) to the liquid crystal polyesteramide resin is 0 to 25 mol%, preferably 1 to 20 mol%, and more preferably 2 to 15 mol%.

Specific examples of monomers that provide the repeating unit represented by formula (V) include terephthalic acid and isophthalic acid, as well as their ester derivatives and ester-forming derivatives such as acid halides.

That is, it is preferable that the repeating unit represented by formula (V) is a repeating unit represented by formula (VI) and/or formula (VII).

In the liquid crystal polyesteramide resin of the present invention, the total composition ratio of the repeating units [p+q+r+s+t] is preferably 100 mol %, but other repeating units may be further included as long as the object of the present invention is not impaired.

Examples of monomers that provide other repeating units constituting the liquid crystal polyesteramide resin of the present invention include other aromatic hydroxycarboxylic acids, other aromatic hydroxyamines, other aromatic dicarboxylic acids or aromatic diols, aromatic hydroxydicarboxylic acids, aromatic diamines, aromatic aminocarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

The proportion of repeat units provided by these other monomer components is preferably 10 mol % or less of the total repeat units.

The method for producing the liquid crystal polyesteramide resin of the present invention is described below.

There are no particular limitations on the method for producing the liquid crystal polyesteramide resin of the present invention, and any known polyester or polyamide polycondensation method that forms an ester bond or amide bond between the above-mentioned monomer components, such as the molten acidolysis method or slurry polymerization method, can be used.

The molten acidolysis method is the preferred method for producing the liquid crystal polyesteramide resin of the present invention. In this method, the polymerizable monomers are first heated to form a molten solution of the reactants, and then the polycondensation reaction is continued to obtain the molten polymer. A vacuum may be applied to facilitate removal of volatile by-products (e.g., acetic acid, water, etc.) produced in the final stage of condensation.

Slurry polymerization is a process in which polymerizable monomers are reacted in the presence of a heat exchange fluid, and a solid product is obtained in a state suspended in the heat exchange medium.

In both the molten acidolysis method and the slurry polymerization method, the polymerizable monomer components used in producing the liquid crystal polyesteramide resin can be subjected to the reaction in a modified form in which the hydroxyl group and/or amino group is acylated, i.e., as a lower acylated product. The lower acyl group preferably has 2 to 5 carbon atoms, and more preferably has 2 or 3 carbon atoms. Particularly preferred is a method in which an acetylated product of the monomer component is used in the reaction.

The lower acylated polymerizable monomer may be a pre-synthesized product obtained by separate acylation, or may be produced in the reaction system by adding an acylating agent such as acetic anhydride to the monomer during the production of the liquid crystal polyester amide resin.

In either the molten acidolysis method or the slurry polymerization method, the polycondensation reaction is usually carried out at a temperature of 150 to 400°C, preferably 250 to 370°C, under normal pressure and/or reduced pressure, and a catalyst may be used as necessary.

Specific examples of catalysts include organotin compounds such as dialkyltin oxides (e.g., dibutyltin oxide) and diaryltin oxides; titanium dioxide; antimony trioxide; organotitanium compounds such as alkoxytitanium silicates and titanium alkoxides; alkali and alkaline earth metal salts of carboxylic acids (e.g., sodium acetate and potassium acetate); gaseous acid catalysts such as Lewis acids (e.g., boron trifluoride) and hydrogen halides (e.g., hydrogen chloride).

The catalyst is usually used in an amount of 10 to 1000 ppm, preferably 20 to 200 ppm, based on the total amount of monomer.

The liquid crystal polyesteramide resin of the present invention thus obtained has a crystalline melting temperature of preferably 200°C or higher as measured by a differential scanning calorimeter (DSC) described below, and has excellent heat resistance. The crystalline melting temperature of the liquid crystal polyesteramide resin of the present invention is preferably 200°C or higher, more preferably 210°C or higher.

In this specification and claims, the "crystalline melting temperature" is determined from the temperature at which an endothermic peak due to crystalline melting is observed when a differential scanning calorimeter (hereinafter abbreviated as DSC) is used to measure at a heating rate of 20°C/min. More specifically, after observing the endothermic peak temperature (Tm1) observed when a sample of liquid crystal polyesteramide resin is measured under heating conditions of 20°C/min from room temperature, the sample is held at a temperature 20 to 50°C higher than Tm1 for 10 minutes, and then cooled to room temperature under a cooling condition of 20°C/min. After that, the endothermic peak is observed when the sample is measured again under heating conditions of 20°C/min, and the temperature showing the peak top is taken as the crystalline melting temperature of the liquid crystal polyesteramide resin. For example, a DSC7020 manufactured by Hitachi High-Tech Science Corporation can be used as a measuring instrument.

The liquid crystal polyesteramide resin of the present invention preferably has a melt viscosity of 1 to 1000 Pa·s, more preferably 5 to 300 Pa·s, as measured using a capillary rheometer (Capillograph 1D manufactured by Toyo Seiki Co., Ltd.) with a capillary of 0.7 mmφ×10 mm under a shear rate of 1000 s ^-1 at a crystal melting temperature +30°C.

In addition, in a tensile test using a dumbbell-shaped test piece (length 63.5 mm × width 3.5 mm × thickness 2.0 mm), the liquid crystal polyester amide resin of the present invention preferably has a tensile strength of 190 MPa or more, more preferably 205 MPa or more, and even more preferably 220 MPa or more. The upper limit of the tensile strength is not particularly limited, but is, for example, 350 MPa.

The tensile strength can be measured with a span distance of 25.4 mm and a tensile speed of 5.0 mm/min.

The liquid crystal polyesteramide resin of the present invention preferably has an Izod impact strength of 300 J/m or more, more preferably 350 J/m or more, and even more preferably 400 J/m or more at 23° C. according to ASTM D256. The upper limit of the Izod impact strength is not particularly limited, but is, for example, 1000 J/m .

The present invention further provides a liquid crystal polyesteramide resin composition obtained by blending one or more fibrous, plate-like or granular fillers with the liquid crystal polyesteramide resin of the present invention. The filler may be appropriately selected from substances known to be used in resin compositions depending on the intended use and application of the liquid crystal polyesteramide resin composition.

Examples of fibrous fillers include glass fiber, silica alumina fiber, alumina fiber, carbon fiber, and aramid fiber. Among these, glass fiber is preferred because it has an excellent balance between physical properties and cost.

Examples of plate-like or granular fillers include talc, mica, graphite, wollastonite, calcium carbonate, dolomite, clay, glass flakes, glass beads, barium sulfate, and titanium oxide. Among these, talc is preferred because it has an excellent balance between physical properties and cost.

In liquid crystal polyesteramide resin compositions containing a filler, the total amount of filler is usually 0.1 to 200 parts by mass, and preferably 10 to 100 parts by mass, per 100 parts by mass of liquid crystal polyesteramide resin. If the amount of filler exceeds 200 parts by mass, the moldability of the resin composition tends to decrease and wear of the cylinder and mold of the molding machine tends to increase.

In addition, the liquid crystal polyesteramide resin of the present invention may further contain one or more of the following additives that are known to be used in resin compositions, such as release improvers such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, higher fatty acid metal salts, polysiloxanes, and fluororesins; colorants such as dyes and pigments; antioxidants; heat stabilizers; ultraviolet absorbers; antistatic agents; and surfactants, in a range that does not impair the effects of the present invention, depending on the purpose and use of the resin composition.

Materials that have an external lubricant effect, such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants, may be attached to the pellets beforehand during molding.

The liquid crystal polyesteramide resin composition of the present invention can be prepared by blending all components such as fillers and additives with polyesteramide resin, and melt-kneading the mixture at a temperature ranging from near the crystalline melting temperature of the liquid crystal polyesteramide resin to the crystalline melting temperature + 100°C using a Banbury mixer, kneader, single-screw or twin-screw extruder, or the like.

The liquid crystal polyesteramide resin and liquid crystal polyesteramide resin composition of the present invention obtained in this manner can be processed into molded articles such as injection molded articles, films, sheets, and nonwoven fabrics by conventional molding methods such as injection molding, compression molding, extrusion molding, and blow molding.

The liquid crystal polyesteramide resin and liquid crystal polyesteramide resin composition of the present invention have excellent mechanical properties such as tensile strength and Izod impact strength, and are therefore suitable for use in electrical and electronic components such as housings and packages for various communication equipment and electronic devices.

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

In the examples, the following abbreviations represent the following compounds.
POB: 4-hydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid BP: 4,4'-dihydroxybiphenyl PAP: 4-aminophenol NDA: 2,6-naphthalenedicarboxylic acid IPA: isophthalic acid TPA: terephthalic acid

Measurement of Crystal Melting Temperature
Measurements were performed using a differential scanning calorimeter (DSC7020 manufactured by Hitachi High-Tech Science Corporation). The resin samples of the following examples and comparative examples were measured under conditions of a temperature rise of 20°C/min from room temperature, and the endothermic peak temperature (Tm1) was observed, and then the sample was held at a temperature 20 to 50°C higher than Tm1 for 10 minutes. The sample was then cooled to room temperature under a temperature drop condition of 20°C/min, and the endothermic peak was observed when measured again under a temperature rise condition of 20°C/min, and the temperature showing the peak top was taken as the crystalline melting temperature of the resin sample.

Tensile strength
Using an injection molding machine (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries, Ltd.), a cylinder temperature of melting point +20 to 40°C and a mold temperature of 70°C were used to mold dumbbell-shaped tensile test pieces having a length of 63.5 mm, a width of 3.5 mm and a thickness of 2.0 mm, and the tensile strength was measured.
The tensile strength was measured at a span distance of 25.4 mm and a pulling speed of 5.0 mm/min.

<Izod impact strength>
Injection molding machine: Using an injection molding machine (MINIMAT M26/15 manufactured by Sumitomo Heavy Industries, Ltd.), a cylinder temperature of melting point +20 to 40°C and a mold temperature of 70°C were used to mold rectangular test pieces having a length of 65 mm, a width of 12.7 mm and a thickness of 2.0 mm. Measurements were performed in accordance with ASTM D256.

Example 1
A reaction vessel equipped with a stirrer with a torque meter and a distillation tube was charged with POB, BON6, PAP, NDA and IPA in a total amount of 6.5 moles in the composition ratios shown in Table 1, and acetic anhydride was further charged in an amount of 1.03 moles relative to the amount (mol) of hydroxyl groups of all monomers, and deacetic acid polymerization was carried out under the following conditions.

The temperature was raised from room temperature to 150°C in a nitrogen gas atmosphere over one hour and maintained at that temperature for 30 minutes. The temperature was then raised quickly to 210°C while distilling off the by-product acetic acid and maintained at that temperature for 30 minutes. The temperature was then raised to 345°C over four hours, after which the pressure was reduced to 10 mmHg over 80 minutes. The polymerization reaction was terminated when a predetermined torque was reached, the contents of the reaction vessel were removed, and pellets of liquid crystal polyesteramide resin were obtained using a grinder. The amount of acetic acid distilled during polymerization was almost the theoretical value.

Examples 2 to 5 and Comparative Examples 1 to 4
Resin pellets were obtained in the same manner as in Example 1, except that the monomer composition ratio was changed to the composition ratio shown in Table 1. The amount of acetic acid distilled during polymerization was approximately the theoretical value.

The crystalline melting temperatures, tensile strengths, and Izod impact strengths of the resins obtained in Examples 1 to 5 and Comparative Examples 1 to 4 are shown in Table 1.

As can be seen from Table 1, all of the liquid crystal polyesteramide resins of Examples 1 to 5, which are composed of specific repeating units, had excellent mechanical properties such as tensile strength and Izod impact strength.

On the other hand, the resins of Comparative Examples 1 to 4 all had inferior mechanical properties, such as tensile strength and Izod impact strength, compared to the liquid crystal polyester amide resins of Examples 1 to 5.

Claims (6)

Formulas (I) to (V)

[In the formula, p, q, r, s and t each represent a composition ratio (mol %) of each repeating unit in the liquid crystal polyester amide resin, and satisfy the following formula:
25≦p≦60,
3≦q≦50,
5≦r≦30,
3≦s≦25, and 0≦t≦25]
The repeating unit is represented by
A liquid crystal polyesteramide resin that satisfies p+q+r+s+t=100 . The liquid crystal polyesteramide resin according to claim 1, further satisfying p+q≧50. The liquid crystal polyesteramide resin according to claim 1 or 2 , which has a tensile strength of 190 MPa or more and 350 MPa or less . The liquid crystal polyesteramide resin according to any one of claims 1 to 3 , which has an Izod impact strength according to ASTM D256 of 300 J/m or more and 1000 J/m or less . A liquid crystal polyesteramide resin composition comprising 0.1 to 200 parts by mass of a fibrous, plate-like or granular filler based on 100 parts by mass of the liquid crystal polyesteramide resin according to any one of claims 1 to 4 . A molded article comprising the liquid crystal polyesteramide resin according to any one of claims 1 to 4 or the liquid crystal polyesteramide resin composition according to claim 5 .