JP7332285B2 - Wholly aromatic polyesteramide, polyesteramide resin composition and polyesteramide molded article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a wholly aromatic polyester amide, a resin composition containing the wholly aromatic polyester amide, and a molded article thereof.

Liquid crystalline polymers are widely used as high-performance engineering plastics because they have a good balance of fluidity, mechanical strength, heat resistance, chemical resistance, electrical properties, and the like. As liquid crystalline polymers, for example, wholly aromatic polyesters obtained by copolymerizing 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and optionally other monomer components are known. In addition, a wholly aromatic polyester amide is known in which an amide group is introduced into a wholly aromatic polyester. Since hydrogen bonds are formed between polymer chains, wholly aromatic polyester amides tend to be superior to wholly aromatic polyesters in performance such as mechanical strength, heat resistance, moldability, and elastic modulus.

Among wholly aromatic polyester amides, those using three specific types as raw material monomers include, for example, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 3-aminobenzoic acid or 4-aminobenzoic acid. Those obtained by copolymerizing acids are known (see Patent Documents 1 to 3).

JP-A-57-177020 Japanese Patent Application Laid-Open No. 2003-128782 Japanese Patent Application Laid-Open No. 2004-339462

However, among the conventional wholly aromatic polyesteramides represented by Patent Documents 1 to 3, in particular, 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-aminobenzoic acid are obtained by copolymerizing The ones obtained are amorphous. Also, such a wholly aromatic polyester amide could not have high strength and high elastic modulus. In order to improve the strength and elastic modulus, it is conceivable to increase the proportion of amide groups and the proportion of hydrogen bonds. However, simply increasing the proportion of amide groups raises the melting point and viscosity, making melt processing difficult.

The present invention has been made in view of the conventional problems described above, and an object of the present invention is to provide a wholly aromatic polyesteramide having melt processability, high strength and high elastic modulus.

One aspect of the present invention for solving the above problems is as follows.

(1) Consists of the following structural units (I), (II) and (III), with 20 to 60 mol% of the following structural unit (I) and 20 to 50 mol of the following structural unit (II) relative to all structural units %, the following structural unit (III) is 15 to 35 mol%, and the ratio of the following structural unit (I) to the following structural unit (II) (structural unit (I)/structural unit (II)) is 0.7 A wholly aromatic polyesteramide that is ∼3.

(2) The wholly aromatic polyesteramide according to (1) above, which has a polystyrene-equivalent weight average molecular weight of 140,000 to 300,000.

(3) The wholly aromatic polyesteramide according to (1) or (2) above, which has a melting point of 240 to 350°C.

(4) A polyesteramide resin composition containing the wholly aromatic polyesteramide described in any one of (1) to (3) above.

(5) A polyesteramide molded article obtained by molding the wholly aromatic polyester described in any one of (1) to (3) above or the polyesteramide resin composition described in (4) above.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a wholly aromatic polyesteramide having melt processability, high strength and high elastic modulus.

<Whole aromatic polyester amide>
The wholly aromatic polyesteramide of the present embodiment is composed of the following structural units (I), (II) and (III), and the following structural unit (I) is 20 to 60 mol% of all structural units, and the following structural unit is (II) is 20 to 50 mol%, the following structural unit (III) is 15 to 35 mol%, and the ratio of the following structural unit (I) to the following structural unit (II) (structural unit (I)/structural unit (II)) is from 0.7 to 3.

The wholly aromatic polyester amide of the present embodiment contains the above structural units (I) to (III) at a content rate within the above range, and the ratio of the above structural unit (I) to the above structural unit (II) is above ratio. Therefore, the wholly aromatic polyester amide is a crystalline resin having an observed melting point at a predetermined temperature, has melt processability, and has high strength and high elastic modulus. The melt processability means the ability to melt and process the polymer using an extruder, an injection molding machine, or the like.
Each structural unit will be described below.

Structural unit (I) is derived from 4-hydroxybenzoic acid (hereinafter also referred to as “HBA”). The wholly aromatic polyesteramide of the present embodiment contains 20 to 60 mol % of the structural unit (I) with respect to all structural units. If the content of the structural unit (I) is less than 20 mol % or more than 60 mol %, the polymer solidifies in the polymerization vessel during production and cannot be sufficiently polymerized. The content of the structural unit (I) is preferably 20 to 55 mol%, more preferably 25 to 55 mol%, even more preferably 25 to 50 mol%, particularly preferably 30 to 50 mol%.

Structural unit (II) is derived from 6-hydroxy-2-naphthoic acid (hereinafter also referred to as "HNA"). The wholly aromatic polyester of the present embodiment contains 20 to 50 mol % of structural units (II) based on all structural units. If the content of the structural unit (II) is less than 20 mol %, the polymer will solidify in the polymerization vessel during production and will not be sufficiently polymerized. Moreover, when the content of the structural unit (II) exceeds 50 mol%, the mechanical strength is lowered. The content of the structural unit (II) is preferably 25 to 50 mol%, more preferably 25 to 45 mol%, even more preferably 30 to 45 mol%, particularly preferably 30 to 40 mol%.

In the present embodiment, the ratio of structural unit (I) to structural unit (II) (structural unit (I)/structural unit (II)) is 0.7-3. If the ratio is less than 0.7, it becomes amorphous and it becomes difficult to carry out solid phase polymerization after melt polymerization. As a result, the molecular weight cannot be increased by solid phase polymerization, and it becomes difficult to obtain a molded product. Furthermore, the mechanical strength is lowered. If the ratio exceeds 3, the melt processability is poor, that is, the viscosity increases, making it difficult to obtain a molded product. The ratio is preferably 0.7-2, more preferably 0.75-2, even more preferably 0.75-1.

Structural unit (III) is derived from 4-aminobenzoic acid (hereinafter also referred to as “pABA”) or 4-acetamidobenzoic acid (hereinafter also referred to as “pAABA”). The wholly aromatic polyesteramide of the present embodiment contains 15 to 35 mol % of the structural unit (III) with respect to all structural units. If the content of the structural unit (III) is less than 15 mol%, the strength and elastic modulus are lowered due to insufficient formation of hydrogen bonds. When the content of the structural unit (III) exceeds 35 mol %, many hydrogen bonds are formed, resulting in poor melt processability, that is, increased viscosity, making it difficult to obtain molded articles. The content of the structural unit (III) is preferably 17.5 to 35 mol%, more preferably 17.5 to 32.5 mol%, still more preferably 20 to 32.5 mol%, particularly preferably 20 to 30 in mol %.
When introducing the structural unit (III), pAABA is used in the examples described later, since the reaction is milder when using pAABA than when using pABA.

As described above, since the wholly aromatic polyester amide of the present embodiment contains the structural units (I) to (III) in a predetermined content, it is a crystalline resin in which a melting point at a predetermined temperature is observed, and melt processability. and has high strength and high modulus. Consequently, the molded article obtained using the wholly aromatic polyester amide of the present embodiment has high strength and high elastic modulus. The wholly aromatic polyesteramide of the present embodiment contains 100 mol % of structural units (I) to (III) in total with respect to all structural units.

Next, properties of the wholly aromatic polyesteramide will be described. The wholly aromatic polyester amide of the present embodiment exhibits optical anisotropy when melted. Exhibiting optical anisotropy when melted means that the wholly aromatic polyesteramide of the present embodiment is a liquid crystalline polymer.

In the present embodiment, the fact that the wholly aromatic polyester amide is a liquid crystalline polymer is an essential factor for the wholly aromatic polyester amide to have both thermal stability and easy processability. Some wholly aromatic polyester amides composed of the above structural units (I) to (III) do not form an anisotropic melt phase depending on the constituent components and the sequence distribution in the polymer. Polymers are limited to wholly aromatic polyesters that exhibit optical anisotropy when melted.

The properties of melt anisotropy can be confirmed by a conventional polarization inspection method using crossed polarizers. More specifically, melting anisotropy can be confirmed by using an Olympus polarizing microscope, melting a sample placed on a Linkcom hot stage, and observing it under a nitrogen atmosphere at a magnification of 150 times. Liquid crystalline polymers are optically anisotropic and transmit light when interposed between crossed polarizers. If the sample is optically anisotropic, polarized light will be transmitted even in the quiescent molten state, for example.

Since a nematic liquid crystalline polymer significantly lowers in viscosity above the melting point, exhibiting liquid crystallinity at a temperature equal to or above the melting point is generally an index of workability. From the viewpoint of heat resistance, the melting point is preferably as high as possible, but considering the thermal deterioration of the polymer during melt processing, the heating capacity of the molding machine, etc., a preferable standard is 360° C. or less. The melting point is preferably 240 to 350°C, more preferably 240 to 340°C, still more preferably 250 to 340°C.

Next, a method for producing the wholly aromatic polyesteramide of the present embodiment will be described. The wholly aromatic polyesteramide of the present embodiment is polymerized using a direct polymerization method, a transesterification method, or the like. In the polymerization, a melt polymerization method, a solution polymerization method, a slurry polymerization method, a solid phase polymerization method, or a combination of two or more thereof is used. is preferably used.

In this embodiment, in the polymerization, an acylating agent for the polymerization monomer or a terminal-activated monomer as an acid chloride derivative can be used. Acylating agents include fatty acid anhydrides such as acetic anhydride.

Various catalysts can be used in these polymerizations, and representative ones include potassium acetate, magnesium acetate, stannous acetate, tetrabutyl titanate, lead acetate, sodium acetate, antimony trioxide, tris ,4-pentanedionato)cobalt (III), and organic compound catalysts such as N-methylimidazole and 4-dimethylaminopyridine. The amount of catalyst used is generally about 0.001 to 1% by weight, preferably about 0.003 to 0.2% by weight, based on the total weight of the monomers.

In the present embodiment, the resin obtained by melt polymerization is further subjected to solid phase polymerization to increase the molecular weight and improve moldability.

A conventionally well-known method can be used for solid phase polymerization. For example, it can be carried out by heating at a temperature 10 to 120° C. lower than the liquid crystal forming temperature of the raw material resin in a stream of inert gas such as nitrogen gas under reduced pressure or vacuum. Since the melting point of the liquid crystalline resin increases as the solid phase polymerization progresses, it is possible to carry out the solid phase polymerization at a temperature equal to or higher than the original melting point of the raw material resin. The solid state polymerization may be carried out at a constant temperature, or the temperature may be increased stepwise. A heating method is not particularly limited, and microwave heating, heater heating, or the like can be used.

In the present embodiment, the polystyrene-equivalent weight average molecular weight of the aromatic polyester amide is preferably 140,000 to 300,000 in terms of obtaining sufficient fluidity during melting while achieving high strength and high elastic modulus. preferable. The weight average molecular weight is preferably 150,000 to 250,000, more preferably 160,000 to 200,000. In the present embodiment, in order to increase the weight average molecular weight of the aromatic polyester amide to 140,000 or more, it is preferable to carry out solid phase polymerization after polymerization such as melt polymerization. Further, in the present embodiment, the polystyrene equivalent weight average molecular weight is based on polystyrene equivalent obtained by gel permeation chromatography (GPC). More specifically, it is determined by the method described in the examples below.

[Polyesteramide resin composition]
The wholly aromatic polyester amide of the present embodiment can be blended with various fibrous, powdery, plate-like inorganic and organic fillers depending on the purpose of use to form a polyester amide resin composition.

Examples of inorganic fillers to be blended in the polyesteramide resin composition of the present embodiment include fibrous, granular, and plate-like fillers.

Examples of fibrous inorganic fillers include glass fiber, silica fiber, silica/alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, silicate fiber such as wollastonite, Inorganic fibrous materials such as magnesium sulfate fibers, aluminum borate fibers, and fibrous materials of metals such as stainless steel, aluminum, titanium, copper, and brass can also be used. A particularly representative fibrous filler is glass fiber.

Examples of powdery inorganic fillers include carbon black, graphite, silica, quartz powder, glass beads, milled glass fiber, glass balloons, glass powder, calcium silicate, aluminum silicate, kaolin, clay, diatomaceous earth, and wollastonite. silicates such as night, iron oxide, titanium oxide, zinc oxide, antimony trioxide, metal oxides such as alumina, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate Salt, other ferrite, silicon carbide, silicon nitride, boron nitride, various metal powders, and the like.

Examples of plate-like inorganic fillers include mica, glass flakes, talc, and various metal foils.

Examples of organic fillers blended in the polyesteramide resin composition of the present embodiment include heat-resistant and high-strength synthetic fibers such as aromatic polyester fibers, liquid crystalline polymer fibers, aromatic polyamide fibers, and polyimide fibers. .

These inorganic and organic fillers can be used alone or in combination of two or more. Combined use of a fibrous inorganic filler and a granular or plate-like inorganic filler is a preferable combination for achieving mechanical strength, dimensional accuracy, electrical properties, and the like. Particularly preferably, glass fiber is used as the fibrous filler, and mica and talc are used as the plate-like filler. Department. By combining the glass fiber with mica or talc, the polyesteramide resin composition has a particularly remarkable improvement in heat distortion temperature, mechanical properties, and the like.

When using these fillers, a sizing agent or a surface treatment agent can be used if necessary.

As described above, the polyesteramide resin composition of the present embodiment contains, as essential components, the wholly aromatic polyesteramide of the present embodiment and, if necessary, an inorganic or organic filler. Other components may be included as long as they are not included. Here, the other component may be any component, and examples thereof include additives such as other resins, antioxidants, stabilizers, pigments, and crystal nucleating agents.

Moreover, the method for producing the polyester resin composition of the present embodiment is not particularly limited, and the polyester resin composition can be prepared by a conventionally known method.

[Polyesteramide molding]
The polyesteramide molded article of the present embodiment is obtained by molding the wholly aromatic polyesteramide or polyesteramide resin composition of the present embodiment. The molding method is not particularly limited, and a general molding method can be adopted. Examples of general molding methods include injection molding, extrusion molding, compression molding, blow molding, vacuum molding, foam molding, rotational molding, gas injection molding, and inflation molding.

The polyesteramide molded article of the present embodiment has high strength and high elastic modulus because it is obtained by molding the above-described wholly aromatic polyesteramide or polyesteramide resin composition of the present embodiment.

Preferable uses of the polyesteramide molded article of the present embodiment having the properties as described above include connectors, CPU sockets, relay switch parts, bobbins, actuators, noise reduction filter cases, and the like.

EXAMPLES The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to the following examples.

[Example 1]
A polymerization vessel equipped with a stirrer, a reflux column, a monomer inlet, a nitrogen inlet, and a pressure reduction/effluent line was charged with the following raw material monomers, a fatty acid metal salt catalyst, and an acylating agent to initiate nitrogen substitution. The following (I) to (III) are monomers from which the structural units (I) to (III) are derived, respectively.
(I) 4-hydroxybenzoic acid: 869 g (40 mol%) (HBA)
(II) 6-hydroxy-2-naphthoic acid: 1183 g (40 mol%) (HNA)
(III) 4-acetamidobenzoic acid: 563 g (20 mol%) (pAABA)
Potassium acetate catalyst: 165 mg
Acetic anhydride: 1310 g (1.02 times the total hydroxyl equivalent of HBA and HNA)
After charging the raw materials, the temperature of the reaction system was raised to 140° C., and the reaction was carried out at 140° C. for 1 hour. After that, the temperature was further raised to 300° C. over 2.8 hours, and the pressure was reduced to 10 Torr (that is, 1330 Pa) over 15 minutes to distill off acetic acid, excess acetic anhydride, and other low-boiling components. condensation was performed. After the stirring torque reaches a predetermined value, nitrogen is introduced to increase the pressure from a reduced pressure state to a normal pressure state to a pressurized state, and the polymer (prepolymer) is discharged from the bottom of the polymerization vessel and pelletized to obtain resin pellets. Ta.
Next, the obtained prepolymer was subjected to heat treatment (solid phase polymerization) at 240° C. for 70 hours under a nitrogen stream to obtain the desired polymer.

<Evaluation>
The resin pellets of Example 1 were subjected to measurement of melting point and weight average molecular weight, and bending test (measurement of bending strength (FS), bending strain and bending elastic modulus (FM)) as follows. Table 1 shows the evaluation results.

[Melting point]
A differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Science Co., Ltd.) was used to measure the endothermic peak temperature (Tm1) observed when the obtained resin pellets were heated from room temperature at a temperature rising rate of 20°C/min. Then, after holding at a temperature of (Tm1 + 40) ° C. for 2 minutes, once cooling to room temperature at a temperature decrease rate of 20 ° C./min, the endothermic peak observed when heating again at a temperature increase rate of 20 ° C./min. was measured as the melting point (Tm2).

[Weight average molecular weight]
The resulting resin pellets were dissolved at room temperature for 6 hours using bistrifluoromethylphenol as a solvent. Gel permeation chromatography ("HLC-8320GPC" manufactured by Tosoh Corporation, differential refractometer detector) was performed, and the weight average molecular weight was calculated in terms of standard polystyrene.

[Bending test]
The obtained resin pellets are molded under the following molding conditions using a small molding machine ("Minishot 2" manufactured by Tsubakimoto Kogyo Co., Ltd.) to prepare a bending test piece of 8.7 mm × 2.6 mm × 3.0 mm. did. Using this test piece, bending strength (FS), bending strain, and bending elastic modulus (FM) were measured. Table 1 shows the measurement results.
(Molding condition)
Cylinder temperature: 300°C

[Example 2, Comparative Examples 1 to 7]
A polymer was obtained in the same manner as in Example 1, except that the types of raw material monomers and the charging ratio (% by mol) were as shown in Table 1. Then, the same evaluation as in Example 1 was performed. Table 1 shows the evaluation results.

From Table 1, it can be seen that good evaluation results were obtained in both Examples 1 and 2 in the bending test.
On the other hand, Comparative Example 1 containing no structural unit (III), Comparative Example 2 with a content of the structural unit (III) of less than 15 mol%, and a comparison with a content of the structural unit (II) exceeding 50 mol% It can be seen that in Example 3, none of them gave good results in the bending test. Further, Comparative Example 4, in which the ratio of the structural unit (I) to the structural unit (II) was less than 0.7, was amorphous and solid phase polymerization could not be performed, and the bending test was not performed. Furthermore, in Comparative Example 5, in which the content of the structural unit (III) exceeds 35 mol%, the polymer (prepolymer) increased in viscosity during polymer synthesis and was not discharged from the bottom of the polymerization vessel. I couldn't do it. Comparative Example 6 in which the content of the structural unit (I) is less than 20 mol% and the content of the structural unit (II) exceeds 50 mol%, and the content of the structural unit (I) is 60 mol% In all of Comparative Example 7 , in which the content of the structural unit (II) was less than 20 mol%, the polymer (prepolymer) solidified during polymer synthesis and was not discharged from the bottom of the polymerization vessel. could not be evaluated.

Claims (4)

Consisting of the following structural units (I), (II) and (III), the following structural unit (I) is 25 to 50 mol%, the following structural unit (II) is 30 to 45 mol%, and the following The structural unit (III) is 15 to 35 mol%, and the ratio of the structural unit (I) below to the structural unit (II) (structural unit (I)/structural unit (II)) is 0.7 to 3. A wholly aromatic polyester amide having a polystyrene-equivalent weight average molecular weight of 140,000 to 300,000.

The wholly aromatic polyesteramide according to claim 1, which has a melting point of 240-350°C. A polyesteramide resin composition containing the wholly aromatic polyesteramide according to claim 1 or 2. A polyesteramide molded article obtained by molding the wholly aromatic polyesteramide according to claim 1 or 2 or the polyesteramide resin composition according to claim 3.