LIQUID CRYSTAL POLYESTER (LCP), LCP COMPOSITION, AND USE THEREOF

Abstract

The present disclosure discloses a liquid crystal polyester (LCP), an LCP composition, and use thereof. The LCP includes a repeating unit of formula (1), a repeating unit of formula (2), and a repeating unit of formula (3): (1) —O—Ar.sup.1—CO—, (2) —CO—Ar.sup.2—CO—, and (3) —O—Ar.sup.3—O—, where Ar.sup.1 is at least one selected from the group consisting of 2,6-naphthylene, 1,4-phenylene, and 4,4′-biphenylene; Ar.sup.2 is selected from the group consisting of 1,4-phenylene, 1,3-phenylene, and 4,4′-biphenylene; and Ar.sup.3 is selected from the group consisting of 2,6-naphthylene, 1,4-phenylene, 1,3-phenylene, and 4,4′-biphenylene; and the LCP has a melting enthalpy of over 1.5 J/g. The LCP and the composition including the LCP of the present disclosure have a high heat deflection temperature (HDT), and exhibit excellent heat resistance and anti-bubbling performance.

Claims

1. A liquid crystal polyester (LCP) comprising a repeating unit of formula (1), a repeating unit of formula (2), and a repeating unit of formula (3):
—O—Ar.sup.1—CO—;  (1)
—CO—Ar.sup.2—CO—; and  (2)
—O—Ar.sup.1—O—;  (3) wherein Ar.sup.1 is at least one selected from the group consisting of 2,6-naphthylene, 1,4-phenylene, and 4,4′-biphenylene; Ar.sup.2 is selected from the group consisting of 1,4-phenylene, 1,3-phenylene, and 4,4′-biphenylene; and Ar.sup.3 is selected from the group consisting of 2,6-naphthylene, 1,4-phenylene, 1,3-phenylene, and 4,4′-biphenylene; and the LCP has a melting enthalpy of over 1.5 J/g, wherein the melting enthalpy is obtained by calculating a melting peak area from a second melting curve obtained by differential scanning calorimetry (DSC).

2. The LCP according to claim 1, comprising the following repeating units in mole percentages: (A) the repeating unit of formula (1), wherein Ar.sup.1 is 2,6-naphthylene: 45 mol % to 65 mol %, (B) the repeating unit of formula (1), wherein Ar.sup.1 is 1,4-phenylene: 1 mol % to 6 mol %; (C) the repeating unit of formula (2), wherein Ar.sup.2 is 1,4-phenylene: 15 mol % to 26 mol %; and (D) the repeating unit of formula (3), wherein A2 is 4,4′-biphenylene: 15 mol % to 26 mol %.

3. The LCP according to claim 2, comprising the following repeating units in mole percentages: (A) the repeating unit of formula (1), wherein Ar.sup.1 is 2,6-naphthylene: 45 mol % to 60 mol %, (B) the repeating unit of formula (1), wherein Ar.sup.1 is 1,4-phenylene: 1 mol % to 5 mol %; (C) the repeating unit of formula (2), wherein Ar.sup.2 is 1,4-phenylene: 19 mol % to 26 mol %; and (D) the repeating unit of formula (3), wherein A2 is 4,4′-biphenylene: 19 mol % to 26 mol %.

4. A preparation method of the LCP according to claim 2, comprising the following steps: S1. subjecting a monomer of the repeating unit of formula (1), a monomer of the repeating unit of formula (3), and an acylating agent to an acylation reaction under catalysis of an ionic liquid (IL); S2. subjecting a product of the acylation reaction of S1 and a monomer of the repeating unit of formula (2) to melt polycondensation and vacuum polycondensation under catalysis of the IL to obtain a prepolymer, wherein during the melt polycondensation, a constant temperature of 280° C. to 300° C. is maintained for 15 min or more; and S3. discharging, cooling, curing, and granulating the prepolymer, and conducting solid-state polymerization (SSP) to obtain the LCP, wherein the IL is obtained through a reaction between a heterocyclic organic base compound with two or more nitrogen atoms and an anionic functional compound.

5. The preparation method of the LCP according to claim 4, wherein in S2, during the melt polycondensation, the constant temperature of 280° C. to 300° C. is maintained for 15 min to 30 min.

6. The preparation method of the LCP according to claim 4, wherein an amount of the IL added is 500 ppm or more of a theoretical yield of the LCP.

7. The preparation method of the LCP according to claim 4, wherein an amount of the IL added is 500 ppm to 3,000 ppm.

8. The preparation method of the LCP according to claim 4, wherein the heterocyclic organic base compound with two or more nitrogen atoms is selected from the group consisting of an imidazole compound, a triazole compound, and a bipyridyl compound, wherein the imidazole compound is selected from the group consisting of 1-methylimidazole, 2-methylimidazole, 4-methylimidazole, 1-ethylimidazole, 2-ethylimidazole, 4-ethylimidazole, 1,2-dimethylimidazole, 1,4-dimethylimidazole, and 2,4-dimethylimidazole.

9. The preparation method of the LCP according to claim 4, wherein the heterocyclic organic base compound with two or more nitrogen atoms is 1-methylimidazole.

10. The preparation method of the LCP according to claim 4, wherein the anionic functional compound is selected from the group consisting of acetic acid, propionic acid, and butyric acid, and is preferably acetic acid.

11. An LCP composition, comprising the following components in parts by weight: TABLE-US-00004 the LCP according to claim 2 50 to 80 parts; and a reinforcing filler 20 to 50 parts, the LCP composition has a melting enthalpy of over 1.0 J/g, and the melting enthalpy is obtained by calculating a melting peak area from a second melting curve obtained by DSC.

12. The LCP composition according to claim 11, wherein the reinforcing filler comprises at least one selected from the group consisting of a fibrous reinforcing filler and a non-fibrous reinforcing filler, wherein the fibrous reinforcing filler has an average length of preferably 20 μm to 2,000 μm, and the non-fibrous reinforcing filler has an average particle size of preferably 0.01 μm to 100 μm.

Description

DETAILED DESCRIPTION

[0061] In order to better illustrate the objective, technical solutions, and advantages of the present disclosure, the present disclosure will be further described below in conjunction with specific examples.

[0062] The raw materials in the following examples and comparative examples are as follows: [0063] HNA: 6-hydroxy-2-naphthoic acid, Sigma-Aldrich; [0064] BP: 4,4′-dihydroxybiphenyl, Sigma-Aldrich; [0065] TA: terephthalic acid, Sigma-Aldrich; [0066] HBA: 4-hydroxybenzoic acid, Sigma-Aldrich; [0067] IA: isophthalic acid, Sigma-Aldrich; [0068] APAP: acetaminophen, Sigma-Aldrich; [0069] magnesium acetate: Sigma-Aldrich; [0070] the glass fiber, talc, mica powder, and titanium dioxide are all commercially available; and the 1-methylimidazole acetate IL is self-made, and a specific preparation method is as follows: 1-methylimidazole and acetic acid are mixed and stirred at 80° C. to allow a reaction for 24 h to obtain the 1-methylimidazole acetate IL.

[0071] The methods for determining a melting temperature, a melting enthalpy, a melt viscosity, an HDT, and anti-bubbling performance in the present disclosure are described as follows:

[0072] (1) Melting temperature: The melting temperature is measured by DSC 200 F3 of NETZSCH. A test sample is heated at a heating rate of 20° C./min from room temperature to a maximum temperature of melting point+(20-80°) C, kept at the maximum temperature for 2 min, then cooled at a cooling rate of 20° C./min to room temperature, then kept at room temperature for 2 min, and then heated at a heating rate of 20° C./min to the maximum temperature of melting point+(20-80°) C, such that a second melting curve of the polymer is obtained; and then a melting peak is selected as a melting point.

[0073] (2) Melting enthalpy: A melting start temperature and a melting end temperature of the melting peak are determined according to the second melting curve obtained in (1), and a melting peak area is calculated as the melting enthalpy.

[0074] (3) Melt viscosity: The melt viscosity is tested with a Dynisco LCR7000 capillary rheometer at a test temperature 30° C. higher than a melting point of the LCP and a shear rate of 1,000 s.sup.−1 through a mouth model with an inner diameter of 1 mm and a length of 40 mm.

[0075] (4) HDT: A test sample is prepared into an 80 mm×10 mm×4 mm specimen through injection molding, and an HDT of the specimen is determined at a heating rate of 2° C./min under a load of 1.82 MPa according to the ISO 75-2 2013 standard.

[0076] (5) Anti-bubbling performance: At a temperature 5° C. higher than the melting point of the LCP and an injection speed of 60 mm/s, the LCP or the composition thereof is molded into a thin sheet specimen with a thickness of 1.0 mm, a length of 60 mm, and a width of 60 mm; and 10 of resulting specimens are placed in a 260° C. oven for 5 min and then taken out, and bubbling conditions on a surface of each specimen are observed. The anti-bubbling performance is measured by a bubbling rate, and the bubbling rate=a number of bubbled specimens/a total number of specimens*100%. The lower the bubbling rate, the better the anti-bubbling performance.

Examples 1 to 8 and Comparative Examples 1 to 8: LCPs

[0077] Raw material components of the LCPs in Examples 1 to 8 and Comparative Examples 1 to 8 were shown in Table 1. A preparation method of the LCP included the following steps:

[0078] S1. Acylation working section: Monomers, acetic anhydride, and a catalyst were added to a first reaction vessel equipped with a stirrer, a monomer feed port, a reflux condenser, a temperature meter, and a nitrogen inlet port, and after the feeding was completed, an atmosphere in the reaction vessel was completely replaced with nitrogen: and a reaction system was heated to 140° C. under protection of nitrogen, and subjected to reflux at this temperature for 2 h to allow an acylation reaction.

[0079] S2. Melt polycondensation working section: After the acylation reaction was completed, a resulting material was transferred to a second reaction vessel equipped with stirrer with a torque sensor, a protective gas inlet port, a discharge unit, and a vacuum unit, stirred, heated at a heating rate of 1° C./min to 280° C. to 300° C., kept at the temperature of 280° C. to 300° C. for a specified time, and then heated at a heating rate of 1° C./min to 360° C., during which acetic acid produced after polymerization was discharged through the discharge unit.

[0080] S3. Vacuum polycondensation working section: After a temperature of the material reached 360° C., a pressure in the second reaction vessel was reduced to 10 kPa within 30 min.

[0081] S4. After the torque reached a set value, nitrogen was introduced through the protective gas inlet port until a pressure in the second reaction vessel reached 0.3 MPa, and then a prepolymer was discharged in a molten state through a discharge port of the second reaction vessel. The prepolymer was cooled, cured, granulated, and fed into a rotary drum to undergo SSP at a temperature of 290° C. and a vacuum level of 100 Pa or lower until the desired melt viscosity is achieved. Then, cooling is performed to obtain an LCP.

[0082] The raw material components, synthesis process parameters, melt viscosities, melting points, melting enthalpies, HDTs, and bubbling rates of the LCPs in Examples 1 to 8 and Comparative Examples 1 to 8 were shown in Table 1.

TABLE-US-00002 TABLE 1 Example/ Example Comparative Example Comparative Example 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 LCP same 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Monomer HNA 2613 3170 3719 3170 3170 3148 3185 3170 3170 3170 3170 4260 2331 — 1901 226 of a (g) repeating unit of formula (1) Monomer BP 1465 1169 878 1169 1169 1246 1117 1169 1169 1169 1169 590 1615 1376 0 409 of a (g) repeating unit of formula (3) Monomer TA 1307 1043 783 1043 1043 1112 997 1043 1043 1043 1043 527 1441 921 0 565 of a (g) repeating unit of formula (2) Monomer BBA 170 169 168 169 169 42 255 169 169 169 169 167 171 3062 3773 1657 of a (g) repeating unit of formula (1) Monomer IA(g) — — — — — — — — — — — 307 — of a repeating unit of formula (2) Other APAP — — — — — — — — — — — — — — — 181 monomers (g) Catalyst 1-methy- 500 500 500 500 3000 500 500 500 — 300 500 500 500 500 500 500 limida- zole acetate IL (ppm) Catalyst Magnesium — — — — — — — — 1500 — — — — — — acetate (ppm) Acylation rate (%) 99.2 99.3 99.0 99.4 99.3 99.4 99.3 99.2 92.3 87.3 99.1 99.2 99.0 99.2 99.3 99.2 Constant temperature 280 280 280 280 280 280 280 300 280 280 280 280 280 280 280 280 (° C.) Constant temperature 30 30 30 15 30 30 30 30 30 30 0 30 30 30 30 30 holding time (min) Melting point of a 342 336 331 333 330 335 331 331 325 331 332 332 315 337 276 330 prepolymer (° C.) Melt viscosity of an LCP 25.1 25.7 24.8 25.3 24.8 25.3 24.6 25.0 24.4 25.8 24.8 24.5 25.4 25.1 25.0 24.8 (Pa .Math. s) Melting point of an LCP 352 345 341 342 341 347 342 340 335 342 344 343 324 352 279 338 (° C.) Melting enthalpy of an 2.14 2.54 2.04 1.89 2.62 2.08 1.92 2.60 1.21 1.33 1.40 1.26 0.82 0.84 0.66 0.58 LCP (J/g) HDT of an LCP (° C.) 300 302 295 293 305 297 294 303 276 281 282 280 258 266 177 240 Bubbling rate (%) 0 0 0 0 0 0 0 0 20 20 10 20 30 60 80 50

[0083] It can be seen from the comparison of results of Examples 1 to 3 and 6 to 7 and Comparative Examples 4 to 8 in Table 1 that the optimization of types and amounts of polymer monomers in the present disclosure is conducive to improvement of a melting enthalpy of an LCP to increase an HDT and reduce a bubbling rate, which is also a reason for the specific further limitation of “the LCP includes the following repeating units in mole percentages: (A) a repeating unit of formula (1), where Ar.sup.1 is 2,6-naphthylene: 45 mol % to 65 mol %; (B) a repeating unit of formula (1), where Ar.sup.1 is 1,4-phenylene: 1 mol % to 6 mol %; (C) a repeating unit of formula (2), where Ar.sup.2 is 1,4-phenylene: 15 mol % to 26 mol %; and (D) a repeating unit of formula (3), where Ar.sup.3 is 4,4′-biphenylene: 15 mol % to 26 mol %” in the present disclosure.

[0084] It can be seen from the results of Examples 2, 4, and 8 and Comparative Example 3 that the melt polycondensation at a constant temperature of 280° C. to 300° C. for 15 min to 30 min during preparation of the LCP is conducive to improving the melting enthalpy of the LCP, thereby increasing HDT and reducing foam generation rate.

[0085] It can be seen from the results of Examples 2 and 5 and Comparative Examples 1 and 2 that, compared with the use of magnesium acetate as a catalyst in Comparative Example 1, the use of a 1-methylimidazole acetate IL as a catalyst in the present disclosure leads to a high acylation rate and is conducive to acquisition of an LCP with a high melting enthalpy, a high HDT, and a low bubbling rate. When an amount of the 1-methylimidazole acetate IL added is 500 ppm or more of a theoretical yield of the LCP, a prominent effect can be allowed.

Examples 1′ to 1′ and Comparative Examples 1′ to 3′: LCP Compositions

[0086] According to the ratio in Table 2, the LCP in each of Examples 1 to 4 and Comparative Example 1 and a reinforcing filler were thoroughly mixed in a high-speed mixer, then fed into a twin-screw extruder, and subjected to melt mixing, extrusion granulation, and cooling to obtain an LCP composition.

[0087] The raw material components, melting enthalpies, HDTs, bubbling rates, and tensile strengths of the LCP compositions obtained in Examples 1′ to 11′ and Comparative Examples 1′ to 3′ were shown in Table 2.

TABLE-US-00003 TABLE 2 Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex- Com- Com- Com- am- am- am- am- am- am- am- am- am- am- am- parative parative parative ple ple ple ple ple ple ple ple ple ple ple Exam- Exam- Exam- 1′ 2′ 3′ 4′ 5′ 6′ 7′ 8′ 9′ 10′ 11′ ple 1′ ple 2′ ple 3′ LCP name 1 2 3 4 2 2 2 2 2 2 2 9 2 2 Melting enthalpy 2.14 2.54 2.04 1.89 2.54 2.54 2.54 2.54 2.54 2.54 2.54 1.21 2.54 2.54 of an LCP (J/g) Content of an LCP 80 80 80 80 50 80 80 80 80 80 80 80 40 90 (parts by weight) Content of a glass 15 15 15 15 15 15 15 15 15 15 15 15 15 fiber (parts by weight) Length of a glass 2000 20 2000 2000 2000 2000 2000 2000 10 3000 2000 2000 2000 2000 fiber (μm) Content of a 5 5 5 5 35 5 5 5 5 5 5 5 45 0 non-fibrous reinforcing filler (parts by weight) Type of a Talc Talc Talc Talc Talc Talc Mica Titanium Talc Talc Talc Talc Talc Talc non-fibrous powder dioxide reinforcing filler Average particle 100 100 100 100 100 100 100 100 100 100 110 100 100 1.00 size of a non-fibrous filler (μm) Melting enthalpy 1.73 1.98 1.63 1.55 1.22 1.75 1.20 1.32 1.41 1.18 1.63 0.97 0.95 1.16 (J/g) HDT (° C.) 301 304 300 299 296 302 295 297 298 291 300 273 263 285 Bubbling rate (%) 0 0 0 0 0 0 0 0 0 0 10 30 10 0 Tensile strength 176 192 195 188 198 186 179 183 155 161 182 178 142 133 (Mpa)

[0088] It can be seen from results of Example 1′, 3′, and 4′ and Comparative Example 1′ that, with the same LCP amount and the same reinforcing filler type and amount, a high melting enthalpy of the LCP leads to a high melting enthalpy, a high HDT, and a low bubbling rate of the LCP composition.

[0089] It can be seen from the results of Example 5′ and Comparative Examples 2′ and 3′ that, with a melting enthalpy of the LCP unchanged, when the LCP and the reinforcing filler are used in a specified ratio, a prepared LCP composition can have excellent heat resistance, anti-bubbling performance, and mechanical performance. Therefore, it is specifically further limited in the present disclosure that “the LCP composition includes the following components in parts by weight: an LCP: 50 to 80 parts; and a reinforcing filler: 20 to 50 parts”.

[0090] It can be seen from results of Examples 2′, 6′, 9′, and 10′ that, when the average length of the glass fiber is in a specified range, the prepared LCP composition can have both excellent HDT and excellent mechanical tensile performance.

[0091] It can be seen from results of Examples 6′ to 8′ and 11′ that, because the non-fibrous reinforcing fillers such as talc, mica powder, and titanium dioxide have a too-large average particle size, the anti-bubbling performance of the prepared LCP composition deteriorates.

[0092] Finally, it should be noted that the above examples are provided merely to describe the technical solutions of the present disclosure, rather than to limit the protection scope of the present disclosure. Although the present disclosure is described in detail with reference to preferred examples, a person of ordinary skill in the art should understand that modifications or equivalent replacements may be made to the technical solutions of the present disclosure without departing from the spirit and scope of the technical solutions of the present disclosure.