Polyaryletherketone copolymer with high Tg and low Tm as well as preparation method and composite material thereof

Abstract

The invention relates to the technical field of polymer synthesis, in particular to a polyaryletherketone copolymer with high Tg and low Tm, a preparation method thereof and a composite material. Comprising the following steps: S1, removing oxygen in a reaction device filled with difluorobenzophenone, dihydroxy diphenyl ether and a reaction solvent under mechanical stirring, then preheating in a protective atmosphere until a homogeneous system is formed, adding a first salt-forming agent, and heating for prepolymerization reaction; s2, adding a diphenol monomer containing a biphenyl structure and a difluoro polyaryl diketone monomer into the reaction system, adding a second salt-forming agent, and heating to carry out a copolymerization reaction; s3, after the reaction is finished, performing post-treatment and precipitation to obtain a polyaryletherketone copolymer with high Tg and low Tm; the material disclosed by the invention has excellent melt flowability and filling capacity, and is suitable for injection molding of complex precise structural parts or thin-wall structural parts.

Description

Technical Field

[0001] This invention relates to the field of polymer synthesis technology, specifically to polyaryl ether ketone copolymers with both high Tg and low Tm, their preparation methods, and composite materials. Background Technology

[0002] Polyaryl ether ketone (PAEK) is a class of special engineering plastics whose molecular backbone is composed of arylene groups, ether bonds, and ketone bonds, with polyether ether ketone (PEEK) as a typical example. PEEK has excellent mechanical properties, heat resistance (Tg=143℃, Tm=343℃) and chemical stability, and is widely used in aerospace, electronics and electrical fields. However, the extremely high melting point (Tm) of PEEK results in a processing temperature as high as 370-420℃, which brings significant drawbacks: (1) High energy consumption and high cost: It requires special high-temperature equipment, and the processing energy consumption is huge. (2) Narrow process window: It is prone to thermal degradation and thermo-oxidative aging at high temperatures, which affects product performance and increases scrap rate. (3) Limited application: The high melt viscosity makes it difficult to use for injection molding of thin-walled products, complex structural parts, or heat-sensitive overmolding scenarios.

[0003] To address the aforementioned issues, existing technologies have explored various approaches. For example, low-melting-point PAEK has been developed by introducing rigid structures. However, these methods often fail to maintain or further increase the glass transition temperature (Tg) while lowering the melting point, leading to a decline in the material's high-temperature performance. Therefore, a long-standing technical challenge in this field is how to significantly reduce the melting point and melt viscosity of PAEK to improve processability without sacrificing or even increasing its glass transition temperature, thereby maintaining its excellent high-temperature performance. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a polyaryl ether ketone copolymer with both high Tg and low Tm, its preparation method, and composite materials. Through polymer structure design and stepwise polymerization, this invention obtains a polyaryl ether ketone material with a high glass transition temperature, low melting point temperature, and low melt viscosity. The material exhibits excellent melt flowability and filling capacity, making it suitable for injection molding complex and precision structural parts or thin-walled structural parts.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] The first aspect of this invention provides a method for preparing a polyaryl ether ketone copolymer that combines high Tg and low Tm, comprising the following steps:

[0007] S1. Under mechanical stirring, oxygen is removed from the reaction apparatus containing benzophenone difluoroacetate, dihydroxydiphenyl ether, and reaction solvent. Then, the mixture is preheated under a protective atmosphere until a homogeneous system is formed. The first salt-forming agent is added, and the temperature is raised to carry out the prepolymerization reaction.

[0008] S2. Add a biphenyl-containing bisphenol monomer and a difluoropolyaryl diketone monomer to the above reaction system, add a second salt-forming agent, and heat to carry out a copolymerization reaction.

[0009] S3. After the reaction is completed, post-treatment is performed to precipitate high Tg and low Tm polyarylether ketone copolymer.

[0010] Furthermore, the difluorobenzophenone is selected from one or more of 4,4'-difluorobenzophenone, 2,2'-difluorobenzophenone, 2,4'-difluorobenzophenone, and 3,3'-difluorobenzophenone; the dihydroxydiphenyl ether is selected from one or more of 4,4'-dihydroxydiphenyl ether, 3-(4-hydroxyphenoxy)phenol, and 2,2'-dihydroxydiphenyl ether.

[0011] Furthermore, the biphenyl-containing diphenol monomer is selected from one or more of biphenyl diphenol (such as 4,4'-biphenyl diphenol), tetramethylbiphenyl diphenol (such as 3,5,3',5'-tetramethyl-4,4'-dihydroxybiphenyl), and dimethylbiphenyl diphenol (such as 3,3'-dimethyl-4,4'-biphenyl diphenol).

[0012] Furthermore, the difluoropolyaryl dione monomer is selected from one or more of 1,3-bis(4-fluorobenzoyl)benzene and 1,3-bis(4-fluorophenyl)propane-1,3-dione.

[0013] Furthermore, both the first and second salt-forming agents are combinations of sodium carbonate and potassium carbonate. The mass percentage of potassium carbonate in the first salt-forming agent is in the range of 0.1%-1%, and the mass percentage of potassium carbonate in the second salt-forming agent is in the range of 0.3%-1%. Preferably, the mass percentage of potassium carbonate in the first salt-forming agent is in the range of 0.2%-0.4%, and the mass percentage of potassium carbonate in the second salt-forming agent is in the range of 0.4%-0.6%. Potassium carbonate mainly accelerates the reaction rate and reduces the condensation residence time, thereby reducing the generation of side reactions such as cross-linking, and playing a role in initiating and stabilizing the transition.

[0014] Furthermore, the amount of the first salt-forming agent added is 50%-65% of the sum of the molar amounts of the difluorobenzophenone and the dihydroxydiphenyl ether; the amount of the second salt-forming agent added is 28%-45% of the sum of the molar amounts of the biphenyl-containing bisphenol monomer and the difluoropolyaryl diketone monomer.

[0015] Furthermore, the molar ratio of the difluorobenzophenone and the dihydroxydiphenyl ether in S1 and the biphenyl-containing bisphenol monomer and the difluoropolyaryl diketone monomer in S2 is 1.05-1.3:1; the molar ratio of the difluorobenzophenone and the dihydroxydiphenyl ether is 1.65-1.75:1; and the molar ratio of the biphenyl-containing bisphenol monomer and the difluoropolyaryl diketone monomer is 1-1.3:2.

[0016] Furthermore, the reaction solvent is selected from diphenyl sulfone; the ratio of the reaction monomer to the reaction solvent is 1 mol: 720-1200 g, and the reaction monomer includes the difluorobenzophenone, the difluoropolyaryl diketone monomer, the dihydroxydiphenyl ether, and the diphenol monomer containing the biphenyl structure.

[0017] Furthermore, the preheating temperature is 145-165℃;

[0018] The prepolymerization reaction is carried out at a temperature of 280-315℃ and a reaction time of 40 min-2 h.

[0019] The copolymerization reaction is carried out at a temperature of 315-350℃ and for a reaction time of 30 min-1 h.

[0020] The heating rate is controlled at 1-3℃ / min.

[0021] A second aspect of the present invention provides a polyarylether ketone copolymer with both high Tg and low Tm prepared by the above preparation method.

[0022] A third aspect of the present invention provides a composite material comprising a polyarylether ketone copolymer with both high Tg and low Tm obtained by the above preparation method as a base material.

[0023] Beneficial technical effects:

[0024] This invention utilizes polymer structure design to randomly copolymerize PEEEK segments with polyether ether ketone ketone segments containing biphenyl structures. The resulting polymer maintains a high glass transition temperature while exhibiting a lower melting point compared to similar products. The polymer produced by this invention has a Tg as high as 178°C and a melting point lower than similar products, even lower than traditional PEEK.

[0025] The products produced by the method of this invention have a low melting point, which can significantly reduce the processing temperature by at least 30°C, thereby reducing energy consumption and equipment requirements. At the same time, the low melt viscosity (up to 200 Pa·s) gives the material excellent melt flowability and filling ability, making it particularly suitable for injection molding of complex and precision structural parts.

[0026] The products produced by the method of this invention can be used in high-end fields that traditional PEEK cannot reach, such as micro-injection molding, long runner precision parts, and overmolding of heat-sensitive electronic components, thereby improving processing performance and broadening application areas.

[0027] This invention employs a stepwise polymerization method, which allows for controllable synthesis processes that are mature, reliable, and easy to industrialize. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specifically stated, the numerical values ​​set forth in these embodiments do not limit the scope of the invention. Techniques and methods known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques and methods should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that values ​​expressed, for example, as "within the range of ab" or "between the range of ab," do not include the endpoint values ​​a and b; values ​​expressed as "for ab," "is ab," or "ab" include the endpoint values ​​a and b.

[0030] Experimental methods not specified in the following examples are generally performed according to national standards; if there is no corresponding national standard, they are performed according to general standard requirements or general methods.

[0031] Example 1

[0032] A method for preparing polyaryl ether ketone copolymers with both high Tg and low Tm includes the following steps:

[0033] S1. In a reaction vessel equipped with a stirrer, nitrogen inlet and outlet, and a condenser, add 107.2 g (0.49 mol) of 4,4'-difluorobenzophenone, 58.62 g (0.29 mol) of 4,4'-dihydroxydiphenyl ether, and 880 mL (1101.76 g) of diphenyl sulfone. Start stirring and introduce nitrogen into the reaction vessel as a protective atmosphere. Purge with nitrogen for more than 1 hour to remove oxygen and moisture. Then, heat to a preheating temperature of 160°C under a nitrogen protective atmosphere and stir until a homogeneous system is formed. Add the first salting agent, which consists of 42.4 g (0.4 mol) of anhydrous sodium carbonate and 0.14 g (0.001 mol) of anhydrous potassium carbonate. Then, raise the temperature to 310°C at a rate of 1°C / min and carry out a prepolymerization reaction at this temperature for 60 minutes to obtain a reaction system containing polyether ether ether ketone prepolymer.

[0034] S2. While maintaining a nitrogen atmosphere and stirring, add 37.26 g (0.2 mol) of 4,4'-biphenyl and 128.92 g (0.4 mol) of 1,3-bis(4-fluorobenzoyl)benzene to the above reaction system containing polyether ether ether ketone prepolymer. Add a second salting agent, which consists of 21.2 g (0.2 mol) of anhydrous sodium carbonate and 0.14 g (0.001 mol) of anhydrous potassium carbonate. Then, heat the mixture to 330°C at a rate of 1°C / min and carry out a copolymerization reaction at this temperature for 40 minutes to obtain a viscous reaction system containing a random copolymer of PEEEK (polyether ether ether ketone) and PEDEKK (polyether ether ketone ketone containing biphenyl structure).

[0035] S3. After the above reaction is completed, the polymer melt of the viscous reaction system obtained above is poured into deionized water to precipitate the copolymer. Then, it is crushed and washed repeatedly with acetone and hot water to completely remove solvent and salt by-products. It is then vacuum dried to constant weight to obtain the polyarylether ketone copolymer of this case.

[0036] Example 2

[0037] A method for preparing polyaryl ether ketone copolymers with both high Tg and low Tm includes the following steps:

[0038] S1. In a reaction vessel equipped with a stirrer, nitrogen inlet and outlet, and a condenser, add 107.50 g (0.49 mol) of 3,3'-difluorobenzophenone, 58.75 g (0.29 mol) of 3-(4-hydroxyphenoxy)phenol, and 950 mL (1189.4 g) of diphenyl sulfone. Start stirring and introduce nitrogen into the reaction vessel as a protective atmosphere. Purge with nitrogen for more than 1 hour to remove oxygen and moisture. Then, under a nitrogen protective atmosphere, heat to a preheating temperature of 165°C and stir until a homogeneous system is formed. Add the first salting agent, which consists of 42.4 g (0.4 mol) of anhydrous sodium carbonate and 0.19 g (0.0014 mol) of anhydrous potassium carbonate. Then, raise the temperature to 300°C at a rate of 3°C / min and carry out a prepolymerization reaction at this temperature for 60 minutes to obtain a reaction system containing polyether ether ether ketone prepolymer.

[0039] S2. While maintaining a nitrogen atmosphere and stirring, add 42.85 g (0.2 mol) of 3,3'-dimethyl-4,4'-biphenyl and 145.04 g (0.45 mol) of 1,3-bis(4-fluorobenzoyl)benzene to the above reaction system containing polyether ether ether ketone prepolymer. Add a second salting agent, which consists of 21.5 g (0.2 mol) of anhydrous sodium carbonate and 0.15 g (0.001 mol) of anhydrous potassium carbonate. Then, heat the mixture to 320°C at a rate of 3°C / min and carry out a copolymerization reaction at this temperature for 60 minutes to obtain a viscous reaction system containing random copolymers of PEEEK and PEDEKK.

[0040] S3. After the above reaction is completed, the polymer melt of the viscous reaction system obtained above is poured into deionized water to precipitate the copolymer. Then, it is crushed and washed repeatedly with acetone and hot water to completely remove solvent and salt by-products. It is then vacuum dried to constant weight to obtain the polyarylether ketone copolymer of this case.

[0041] Example 3

[0042] A method for preparing polyaryl ether ketone copolymers with both high Tg and low Tm includes the following steps:

[0043] S1. In a reaction vessel equipped with a stirrer, nitrogen inlet and outlet, and a condenser, add 100.74 g (0.46 mol) of 4,4'-difluorobenzophenone, 60.66 g (0.30 mol) of 4,4'-dihydroxydiphenyl ether, and 1000 mL (1252 g) of diphenyl sulfone. Start stirring and introduce nitrogen into the reaction vessel as a protective atmosphere. Purge with nitrogen for more than 1 hour to remove oxygen and moisture. Then, heat to a preheating temperature of 155°C under a nitrogen protective atmosphere and stir until a homogeneous system is formed. Add the first salting agent, which consists of 42.4 g (0.4 mol) of anhydrous sodium carbonate and 1.38 g (0.01 mol) of anhydrous potassium carbonate. Then, raise the temperature to 305°C at a rate of 2°C / min and carry out a prepolymerization reaction at this temperature for 60 minutes to obtain a reaction system containing polyether ether ether ketone prepolymer.

[0044] S2. While maintaining a nitrogen atmosphere and stirring, add 44.69 g (0.24 mol) of 4,4'-biphenyl and 129.30 g (0.4 mol) of 1,3-bis(4-fluorobenzoyl)benzene to the above reaction system containing polyether ether ether ketone prepolymer. Add a second salting agent, which consists of 23.32 g (0.22 mol) of anhydrous sodium carbonate and 0.41 g (0.003 mol) of anhydrous potassium carbonate. Then, heat the mixture to 325 °C at a rate of 2 °C / min and carry out a copolymerization reaction at this temperature for 50 minutes to obtain a viscous reaction system containing random copolymers of PEEEK and PEDEKK.

[0045] S3. After the above reaction is completed, the polymer melt of the viscous reaction system obtained above is poured into deionized water to precipitate the copolymer. Then, it is crushed and washed repeatedly with acetone and hot water to completely remove solvent and salt by-products. It is then vacuum dried to constant weight to obtain the polyarylether ketone copolymer of this case.

[0046] Comparative Example 1

[0047] The preparation process of the polymer in this case is the same as that in Example 1, except that the second polymerization reaction in S2 is not carried out. Instead, the reaction in step S1 is carried out directly in step S3 after 100 minutes.

[0048] Comparative Example 2

[0049] This case is a standard PEEK (JUNHUA PEEK5600G).

[0050] Comparative Example 3

[0051] This case study uses commercially available low-melting-point PAEK—LMPAEK (VICTREX).

[0052] Comparative Example 4

[0053] The preparation process of the polymer in this case is the same as in Example 1, except that in step S1, 4,4'-dihydroxydiphenyl ether is replaced with an equimolar amount of hydroquinone.

[0054] Comparative Example 5

[0055] The preparation process of the polymer in this case is the same as in Example 1, except that 1,3-bis(4-fluorobenzoyl)benzene was not added in step S2.

[0056] Comparative Example 6

[0057] The preparation process of the polymer in this case is the same as that in Example 1, except that step-by-step polymerization is not performed. Instead, 4,4'-difluorobenzophenone, 4,4'-dihydroxydiphenyl ether, 4,4'-biphenylhydrazine, 1,3-bis(4-fluorobenzoyl)benzene, anhydrous sodium carbonate and anhydrous potassium carbonate (the amount of each substance is kept the same as in Example 1) are added directly in step S1 to carry out polymerization in a one-pot manner.

[0058] Comparative Example 7

[0059] The preparation process of the polymer in this case is the same as in Example 1, except that potassium carbonate is not added to the first salting agent and the second salting agent.

[0060] Comparative Example 8

[0061] The preparation process of the polymer in this case is the same as in Example 1, except that the first salting agent is entirely potassium carbonate and the second salting agent is entirely potassium carbonate (the amount of salting agent used is the same as in Example 1).

[0062] Test case

[0063] The polymer properties of the above cases are shown in Table 1.

[0064] Table 1 Polymer Properties of Examples and Comparative Examples

[0065]

[0066] As shown in Table 1, the polyarylether ketone copolymer of the present invention exhibits a higher Tg and a lower Tm compared to traditional PEEK and commercially available low-melting-point products, and also demonstrates superior mechanical properties. Example 2 is structurally similar to Example 1, with only minor adjustments to the monomer type, ratio, or process parameters. Therefore, it achieves a higher Tg of 173-175°C, but a significantly lower Tm than PEEK, resulting in better mechanical properties than the comparative example. Example 3 is structurally similar to Example 1, but the total potassium carbonate content in S1 and S2 is slightly higher, leading to a faster reaction rate and a higher Tm compared to the other two examples, resulting in a larger deviation in mechanical properties.

[0067] Comparative Example 4 used hydroquinone instead of 4,4'-dihydroxydiphenyl ether, resulting in improved chain segment regularity, decreased Tg, increased Tm, and slightly lower mechanical properties compared to Example 1. Comparative Example 5 did not include the difluoropolyaryl diketone monomer, resulting in an incomplete copolymer structure, increased Tm, slightly decreased Tg, and decreased mechanical properties. Comparative Example 6 used a one-pot polymerization method, which may have broadened the molecular weight distribution, slightly decreased Tg, slightly increased Tm, and slightly worse performance compared to Example 1. Comparative Example 7 lacked potassium carbonate catalysis, potentially leading to incomplete reaction and a lower polymer molecular weight, thus reducing Tg, Tm, and mechanical properties. Comparative Example 8, using potassium carbonate catalysis throughout, had an excessively fast reaction rate, potentially resulting in uneven molecular weight distribution and worse performance than Example 1.

[0068] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing polyaryl ether ketone copolymers possessing both high Tg and low Tm, characterized in that, Includes the following steps: S1. Under mechanical stirring, oxygen is removed from the reaction apparatus containing benzophenone difluoroacetate, dihydroxydiphenyl ether, and reaction solvent. Then, the mixture is preheated under a protective atmosphere until a homogeneous system is formed. The first salt-forming agent is added, and the temperature is raised to carry out the prepolymerization reaction. S2. Add a biphenyl-containing bisphenol monomer and a difluoropolyaryl diketone monomer to the above reaction system, add a second salt-forming agent, and heat to carry out a copolymerization reaction. S3. After the reaction is completed, post-treatment is performed to precipitate high Tg and low Tm polyarylether ketone copolymer.

2. The method for preparing the polyaryl ether ketone copolymer with both high Tg and low Tm according to claim 1, characterized in that, The difluorobenzophenone is selected from one or more of 4,4'-difluorobenzophenone, 2,2'-difluorobenzophenone, 2,4'-difluorobenzophenone, and 3,3'-difluorobenzophenone; The dihydroxydiphenyl ether is selected from one or more of 4,4'-dihydroxydiphenyl ether, 3-(4-hydroxyphenoxy)phenol, and 2,2'-dihydroxydiphenyl ether; The biphenyl monomer containing the biphenyl structure is selected from one or more of biphenyl hydrophenol, tetramethylbiphenyl hydrophenol, and dimethylbiphenyl hydrophenol. The difluoropolyaryl dione monomer is selected from one or more of 1,3-bis(4-fluorobenzoyl)benzene and 1,3-bis(4-fluorophenyl)propane-1,3-dione.

3. The method for preparing the polyaryl ether ketone copolymer with both high Tg and low Tm according to claim 2, characterized in that, Both the first salt-forming agent and the second salt-forming agent are combinations of sodium carbonate and potassium carbonate. In the first salt-forming agent, the mass percentage of potassium carbonate is in the range of 0.1%-1%, and in the second salt-forming agent, the mass percentage of potassium carbonate is 0.3%-1%.

4. The method for preparing the polyaryl ether ketone copolymer with both high Tg and low Tm according to claim 3, characterized in that, The amount of the first salting agent added is 50%-65% of the sum of the molar amounts of the difluorobenzophenone and the dihydroxydiphenyl ether; the amount of the second salting agent added is 28%-45% of the sum of the molar amounts of the biphenyl-containing diphenol monomer and the difluoropolyaryl diketone monomer.

5. The method for preparing the polyaryl ether ketone copolymer with both high Tg and low Tm according to any one of claims 1-4, characterized in that, The molar ratio of difluorobenzophenone and dihydroxydiphenyl ether in S1 and the molar ratio of the biphenyl-containing diphenol monomer and the difluoropolyaryl diketone monomer in S2 is 1.05-1.3:1; the molar ratio of difluorobenzophenone and dihydroxydiphenyl ether is 1.65-1.75:1; and the molar ratio of the biphenyl-containing diphenol monomer and the difluoropolyaryl diketone monomer is 1-1.3:

2.

6. The method for preparing the polyaryl ether ketone copolymer with both high Tg and low Tm according to any one of claims 1-4, characterized in that, The reaction solvent is selected from diphenyl sulfone; the ratio of the reaction monomer to the reaction solvent is 1 mol: 720-1200 g, and the reaction monomer includes the difluorobenzophenone, the difluoropolyaryl diketone monomer, the dihydroxydiphenyl ether and the diphenol monomer containing the biphenyl structure.

7. The method for preparing the polyaryl ether ketone copolymer with both high Tg and low Tm according to any one of claims 1-4, characterized in that, The preheating temperature is 145-165℃; The prepolymerization reaction is carried out at a temperature of 280-315℃ and a reaction time of 40 min-2 h. The copolymerization reaction is carried out at a temperature of 315-350℃ and for a reaction time of 30 min-1 h. The heating rate is controlled at 1-3℃ / min.

8. A polyaryl ether ketone copolymer possessing both high Tg and low Tm, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. A composite material, characterized in that, The base material includes a polyarylether ketone copolymer with both high Tg and low Tm prepared by the preparation method according to any one of claims 1-7.

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