Polyester and its preparation method and application

Abstract

The present invention relates to a polyester, a preparation method, and applications thereof. The polyester has the following structure: where n is 10-100. The polyester has a low dielectric constant of 2.6-2.7 at 2.5 GHz and can be applied to electronic products or the automotive field, meeting the needs of the 5G era.

Description

Technical Field

[0001] The present invention relates to the field of polyester materials, in particular to polyester and a preparation method and application thereof. Background Art

[0002] To meet the demands of the 5G era, miniaturization and lightweighting of electronic products, coupled with increasing requirements for high signal transmission speeds, low transmission loss, and signal integrity, have garnered widespread attention regarding the dielectric properties of polymer materials, with low-dielectric-constant polymer materials becoming a research focus. Polyester, a widely used general-purpose engineering plastic, boasts excellent mechanical properties, heat and wear resistance, and dimensional stability, offering broad application prospects in the field of low-dielectric engineering plastics.

[0003] Common polyesters currently on the market, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), have dielectric constants exceeding 2.9 at frequencies greater than 1 GHz, failing to meet the growing demand for polymer materials in the electronics sector. The rapid development of 5G technology, in particular, places higher demands on the dielectric properties of polyester in applications ranging from mobile phone signal transmission components to intelligent driving sensor materials, in order to achieve high-speed, low-latency information transmission. Summary of the Invention

[0004] The present invention aims to overcome the problems existing in the above-mentioned prior art and provide a polyester and its preparation method and application. The polyester has a low dielectric constant and meets the needs of the 5G era.

[0005] The first aspect of the present invention is to provide a polyester having the following structure:

[0006] , n value is 10-100.

[0007] Preferably, the polyester has a weight average molecular weight of 5,000-50,000 and a molecular weight distribution index of 1.5-2.5.

[0008] Preferably, the dielectric constant of the polyester is 2.6-2.7.

[0009] The second aspect of the present invention is to provide a method for preparing the aforementioned polyester, which comprises subjecting monomer A and monomer B to a condensation reaction to obtain the aforementioned polyester; the monomer A is 1,4-cyclohexanedicarboxylic acid, and the monomer B is hydrogenated bisphenol A and / or hydrogenated bisphenol A dicarboxylate; or, the monomer A is a 1,4-cyclohexanedicarboxylate, and the monomer B is hydrogenated bisphenol A.

[0010] Preferably, the 1,4-cyclohexanedicarboxylic acid esters include one or more of dimethyl 1,4-cyclohexanedicarboxylate, diethyl 1,4-cyclohexanedicarboxylate, dipropyl 1,4-cyclohexanedicarboxylate, dialkyl 1,4-cyclohexanedicarboxylate and diaromatic 1,4-cyclohexanedicarboxylate; and the hydrogenated bisphenol A dicarboxylate includes hydrogenated bisphenol A dicarboxylate and / or hydrogenated bisphenol A diacetate.

[0011] Preferably, the molar ratio of the A monomer to the B monomer is (0.99-1.01):1.

[0012] Preferably, the polycondensation reaction comprises the following steps:

[0013] S1. Mix monomer A and monomer B, heat them under a protective atmosphere until they are melted, then add a catalyst, stir and react, continue heating to 190-215°C for the first time, and stir and react for 2-4 hours;

[0014] S2, vacuum the reaction for 2-3 hours, and during the reaction, the temperature is raised to 220-240°C for the second time;

[0015] S3, heating to 245-260° C. for the third time, reacting for 1-2 hours to obtain the polyester.

[0016] Preferably, the system pressure in step S2 is 500-1000 Pa; and the system pressure in step S3 is lower than 200 Pa.

[0017] Preferably, the catalyst is added in batches, with the batches being 1 to 4 times.

[0018] Preferably, the content of the catalyst is 0.04%-0.2% of the total mass of the A monomer and the B monomer.

[0019] Preferably, the catalyst is one or more of a titanium-based catalyst, a tin-based catalyst, an antimony-based catalyst, a germanium-based catalyst and a metal acetate catalyst.

[0020] The third aspect of the present invention is to provide an application of the aforementioned polyester or the polyester obtained by the aforementioned preparation method in the field of electronic products or automobiles.

[0021] The polyester provided by the present invention contains a large number of cyclohexane structural units, which can increase the free volume of the polyester molecules and reduce the dielectric constant of the polyester. The low dielectric constant polyester meets the needs of the 5G era and can be well applied to electronic products or the automotive field.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0023] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0024] The present invention provides a polyester having the following structure:

[0025] , The value of n is 10 to 100. The large amount of cyclohexane units in the polyester structure can increase the free volume of the polyester molecules and reduce the dielectric constant of the polyester.

[0026] In the present invention, the polyester has a weight average molecular weight of 5,000-50,000 and a molecular weight distribution index of 1.5-2.5. Preferably, the polyester has a dielectric constant of 2.6-2.7 at 2.5 GHz, which is lower than that of currently common polyesters.

[0027] The present invention also provides a method for preparing the aforementioned polyester, which comprises subjecting monomer A and monomer B to a condensation reaction to obtain the aforementioned polyester; the monomer A is 1,4-cyclohexanedicarboxylic acid, and the monomer B is hydrogenated bisphenol A and / or hydrogenated bisphenol A dicarboxylate; or, the monomer A is a 1,4-cyclohexanedicarboxylate, and the monomer B is hydrogenated bisphenol A.

[0028] In the present invention, the A monomer is 1,4-cyclohexanedicarboxylic acid and / or a 1,4-cyclohexanedicarboxylic acid ester. The present invention does not limit the structure of the A monomer, and it can be a cis-structure and / or a trans-structure. Specifically, the 1,4-cyclohexanedicarboxylic acid (CHDA) can be selected from cis-structure CHDA (e.g., CAS: 619-81-8), trans-structure CHDA (e.g., CAS: 619-82-9), and a cis-trans isomer mixture of CHDA (e.g., CAS: 1076-97-7). The 1,4-cyclohexanedicarboxylic acid ester includes, but is not limited to, one or more of dimethyl 1,4-cyclohexanedicarboxylate, diethyl 1,4-cyclohexanedicarboxylate, dipropyl 1,4-cyclohexanedicarboxylate, dialkyl 1,4-cyclohexanedicarboxylate, and diaromatic 1,4-cyclohexanedicarboxylate. The 1,4-cyclohexanedicarboxylic acid ester can have a cis-structure and / or a trans-structure.

[0029] In the present invention, the B monomer is hydrogenated bisphenol A and / or hydrogenated bisphenol A dicarboxylate. The present invention does not limit the structure of the A monomer and can have a cis- or trans-structure. The hydrogenated bisphenol A dicarboxylate includes hydrogenated bisphenol A diformate and / or hydrogenated bisphenol A diacetate. It should be noted that hydrogenated bisphenol A is also known as 2,2-bis-(4-hydroxycyclohexyl)propane.

[0030] In the present invention, the molar ratio of monomer A to monomer B is (0.99-1.01):1, which is conducive to the synthesis of high molecular weight polyester; too much or too little will result in too low molecular weight of polyester, which is not conducive to the mechanical properties of the material.

[0031] In the present invention, the polycondensation reaction comprises the following steps:

[0032] S1. Mix monomer A and monomer B, heat them under a protective atmosphere until they are melted, then add a catalyst, stir and react, continue heating to 190-215°C for the first time, and stir and react for 2-4 hours;

[0033] S2, vacuum the reaction for 2-3 hours, and during the reaction, the temperature is raised to 220-240°C for the second time;

[0034] S3, heating to 245-260° C. for the third time, reacting for 1-2 hours to obtain the polyester.

[0035] Specifically, monomer A and monomer B in step S1 are mixed in a molar ratio of (0.99-1.01):1, added to a reaction vessel, and heated under a protective atmosphere (such as nitrogen) until monomer A and monomer B are melted. A catalyst is then added to promote the reaction. Preferably, the catalyst is added in batches of 1-4 times. Adding the catalyst in batches can compensate for losses caused by catalyst volatilization and catalyst carryover with the small molecule product, thereby facilitating the reaction and increasing the molecular weight of the product.

[0036] In the present invention, the content of the catalyst is 0.04%-0.2% of the total mass of the monomers A and B. The catalyst can be a catalyst commonly used in the art, for example, it can be selected from one or more of titanium catalysts, tin catalysts, antimony catalysts, germanium catalysts, and metal acetate catalysts. The titanium catalyst includes but is not limited to one or more of tetrabutyl titanate, tetraethyl titanate, and tetraisopropyl titanate; the tin catalyst includes but is not limited to one or more of dibutyltin diacetate, dibutyltin oxide, and dibutyltin dilaurate; the antimony catalyst is selected from antimony trioxide, antimony glycol, etc.; the germanium catalyst includes but is not limited to germanium dioxide; and the metal acetate catalyst includes but is not limited to zinc acetate, magnesium acetate, and cadmium acetate.

[0037] In the present invention, step S2 requires a vacuum reaction, and the temperature is raised to 220-240°C for the second time during the reaction. This is because after completing step S1, the system viscosity increases, and it is necessary to continue to raise the temperature to reduce the viscosity. The vacuum degree is gradually increased to discharge small molecule byproducts, shift the equilibrium toward the positive direction, and increase the degree of polymerization. It should be noted that during the vacuum process, the system vacuum degree will gradually increase and the system pressure will gradually decrease. Preferably, the system pressure in step S2 is 500-1000 Pa.

[0038] In the present invention, to further reduce the system viscosity, promote the forward reaction, and increase the degree of polymerization and molecular weight, step S3 is required to heat the reaction to 240-260°C for a third time for 1-2 hours to obtain the polyester. Preferably, the system pressure in step S3 is less than 200 Pa.

[0039] The present invention also provides the use of the aforementioned polyester or the polyester obtained by the aforementioned preparation method in electronic products or automotive applications. Preferably, the polyester can be used in mobile phone terminal signal transmission components or vehicle intelligent driving sensors. The polyester has a low dielectric constant, adapting to the needs of the 5G era.

[0040] The present invention will be described in detail below through examples, but the present invention is not limited to the following examples.

[0041] Molecular weight test: The weight average molecular weight and molecular weight distribution index of the solution polyester were determined by gel permeation chromatography using SH 1759-2007.

[0042] Dielectric constant test: Resonant cavity method, using GB / T 1409-2006, the recommended method for measuring the permittivity and dielectric loss factor of electrical insulating materials at power frequency, audio frequency, and high frequency (including meter wave wavelength).

[0043] Example 1

[0044] (1) 43 g (0.25 mol) of 1,4-cyclohexanedicarboxylic acid (purchased from Aladdin Reagent, CAS No. 1076-97-7) and 60 g (0.25 mol) of hydrogenated bisphenol A (purchased from MacLean Reagent, CAS No. 80-04-6) were added to a 250 ml three-necked flask. Under nitrogen protection, the reaction system was heated to 180 °C. After the reactants were completely melted, 51.5 mg (0.05 wt%) of tetrabutyl titanate was added dropwise. After the reaction was completed for 2 h, another 51.5 mg (0.05 wt%) of tetrabutyl titanate was added dropwise and mechanically stirred. The reaction system was heated to 200 °C and reacted for 2 h.

[0045] (2) Continue to raise the temperature to 220°C. When no more water is distilled out of the reaction system, connect the system to a vacuum pump, gradually increase the vacuum degree of the system, reduce the system pressure, and at the same time increase the system temperature at a rate of 10°C / h. React for 2 hours.

[0046] (3) The temperature was further raised to 250°C, the system pressure was 150 Pa, and the reaction was continued for 1 hour to obtain the final polyester A1, whose structure is:

[0047]

[0048] , where 30<n<35, the reaction process to obtain A1 is as follows:

[0049] .

[0050] The weight average molecular weight of polyester A1 is 25,000, the molecular weight distribution index is 1.9, and the dielectric constant is 2.61 at 2.5 GHz.

[0051] Example 2

[0052] (1) Add 43 g (0.25 mol) of 1,4-cyclohexanedicarboxylic acid and 60 g (0.25 mol) of hydrogenated bisphenol A to a 250 ml three-necked flask. Heat the reaction system to 180 °C under nitrogen protection. After the reactants are completely melted, add 103 mg (0.1 wt%) of tetrabutyl titanate dropwise. After reacting for 2 h, heat the reaction system to 200 °C and react for 2 h.

[0053] (2) Continue to raise the temperature to 220°C. When no more water is distilled out of the reaction system, connect the system to a vacuum pump and gradually increase the vacuum degree of the system. At the same time, increase the system temperature at a rate of 10°C / h and react for 2h.

[0054] (3) The temperature was further raised to 250°C, the system pressure was 150 Pa, and the reaction was continued for 1 hour to obtain the final polyester A2, whose structure is:

[0055]

[0056] , where 23<n<28.

[0057] The weight average molecular weight of polyester A2 is 19,000, the molecular weight distribution index is 2.1, and the dielectric constant is 2.66 at 2.5 GHz.

[0058] Example 3

[0059] The preparation method is the same as that of Example 1, except that the raw material 1,4-cyclohexanedicarboxylic acid is replaced with dimethyl 1,4-cyclohexanedicarboxylate (purchased from Aladdin Reagent, CAS No. 94-60-0). The final polyester A3 is obtained, and its structure is:

[0060]

[0061] , where 25<n<30, the reaction process to obtain A3 is as follows:

[0062] .

[0063] The weight average molecular weight of polyester A3 is 21,600, the molecular weight distribution index is 1.9, and the dielectric constant is 2.64 at 2.5 GHz.

[0064] Example 4

[0065] The preparation method is the same as that of Example 1, except that the raw material hydrogenated bisphenol A is replaced with hydrogenated bisphenol A diacetate. Finally, the final polyester A4 is obtained, and its structure is:

[0066]

[0067] , where 20<n<25, the reaction process to obtain A4 is as follows:

[0068] .

[0069] The weight average molecular weight of polyester A4 is 15,000, the molecular weight distribution index is 2.3, and the dielectric constant is 2.68 at 2.5 GHz.

[0070] Example 5

[0071] The preparation method is the same as that in Example 1, except that 46.5 g (0.27 mol) of 1,4-cyclohexanedicarboxylic acid and 60 g (0.25 mol) of hydrogenated bisphenol A are used. The final polyester A5 is obtained, and its structure is:

[0072]

[0073] , where 5<n<10.

[0074] The weight average molecular weight of polyester A5 is 4960, the molecular weight distribution index is 2.2, and the dielectric constant is 2.71 at 2.5 GHz.

[0075] Comparative Example 1

[0076] Polyethylene terephthalate (purchased from Tamron Special Resins, product code TL102) has a weight average molecular weight of 59,000 and a molecular weight distribution index of 2.4; and a dielectric constant of 3.0 at 2.5 GHz.

[0077] Comparative Example 2

[0078] The preparation method is the same as that of Example 1, except that the raw material hydrogenated bisphenol A is replaced with 1,4-butanediol (purchased from Sinopharm Reagent, CAS No. 110-63-4). Finally, the final polyester D2 is obtained, and its structure is:

[0079] .

[0080] The weight average molecular weight of polyester D2 is 44,000, the molecular weight distribution index is 2.5, and the dielectric constant is 2.97 at 2.5 GHz.

[0081] It should be noted that a lower dielectric constant results in faster signal transmission and reduced transmission loss. Therefore, as long as other material properties are not affected, a lower dielectric constant is preferred. Existing low-dielectric polymers have a dielectric constant above 2.9, which barely meets the low-frequency requirements of 5G. However, as signal frequencies increase, the dielectric constant at high-frequency 5G frequencies generally falls below 2.7. The results of the Examples and Comparative Examples demonstrate that the polyesters provided by the present invention exhibit a low dielectric constant at 2.5 GHz, meeting the high-frequency requirements of 5G.

[0082] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0083] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0084] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A polyester, characterized in that The polyester has the following structure: The n value is 10-100; the weight average molecular weight of the polyester is 5000-25000; the dielectric constant of the polyester is 2.6-2.7, and the molecular weight distribution index of the polyester is 1.5-2.

5.

2. A method for preparing polyester, characterized in that: The method comprises subjecting monomer A and monomer B to a condensation polymerization reaction to obtain the polyester according to claim 1; the monomer A is 1,4-cyclohexanedicarboxylic acid, and the monomer B is hydrogenated bisphenol A and / or hydrogenated bisphenol A dicarboxylate; or, the monomer A is a 1,4-cyclohexanedicarboxylate, and the monomer B is hydrogenated bisphenol A; and the weight-average molecular weight of the polyester is 5,000-25,000.

3. The preparation method according to claim 2, characterized in that The 1,4-cyclohexanedicarboxylic acid esters include one or more of dimethyl 1,4-cyclohexanedicarboxylate, diethyl 1,4-cyclohexanedicarboxylate, dipropyl 1,4-cyclohexanedicarboxylate, dialkyl 1,4-cyclohexanedicarboxylate and diaromatic 1,4-cyclohexanedicarboxylate; the hydrogenated bisphenol A dicarboxylate includes hydrogenated bisphenol A dicarboxylate and / or hydrogenated bisphenol A diacetate.

4. The preparation method according to claim 2, characterized in that The molar ratio of the A monomer to the B monomer is (0.99-1.01):

1.

5. The preparation method according to claim 2, characterized in that The polycondensation reaction comprises the following steps: S1. Mix monomer A and monomer B, heat them under a protective atmosphere until they are melted, then add a catalyst, stir and react, continue heating to 190-215°C for the first time, and stir and react for 2-4 hours; S2, vacuum the reaction for 2-3 hours, and during the reaction, the temperature is raised to 220-240°C for the second time; S3, heating to 245-260° C. for the third time, reacting for 1-2 hours to obtain the polyester.

6. The preparation method according to claim 5, characterized in that The system pressure in step S2 is 500-1000 Pa; the system pressure in step S3 is lower than 200 Pa.

7. The preparation method according to claim 5, characterized in that The catalyst is added in batches, with the batches being 1 to 4 times.

8. The preparation method according to claim 5, characterized in that The content of the catalyst is 0.04%-0.2% of the total mass of the A monomer and the B monomer.

9. The preparation method according to claim 5, characterized in that The catalyst is one or more of a titanium-based catalyst, a tin-based catalyst, an antimony-based catalyst, a germanium-based catalyst and a metal acetate catalyst.

10. Use of the polyester according to claim 1 or the polyester obtained by the preparation method according to any one of claims 2 to 9 in the field of electronic products or automobiles.

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