A kind of polyetherketone resin and preparation method thereof

Abstract

A polyetherketone resin and a preparation method thereof belong to the field of polyaryletherketone materials. Due to the high rigidity molecular chain of PEK itself and the harsh ether-ketone alternating structure, its polymerization reaction has the characteristics of low activity and many side reactions. This application reduces and avoids the influence of water molecules on the reaction in the later stage of the reaction from many aspects by strictly controlling the reaction conditions and using raw materials corresponding to the conditions, thereby improving the reaction efficiency and reducing side reactions. The obtained PEK resin product has a glass transition temperature of 152±1°C and a melting point of 370~375°C; it can be dissolved in meta-chlorophenol (50g / L, 170°C).

Description

Technical Field

[0001] The invention belongs to the field of polyaryletherketone materials, in particular to a polyetherketone resin and a preparation method thereof. Background Art

[0002] Polyaryletherketone (PAEK) is a type of high-performance thermoplastic resin with excellent mechanical properties, processing properties, chemical resistance, impact resistance, radiation resistance, self-lubrication, etc. Common polyaryletherketones are linear structures, including polyetheretherketone (PEEK), polyetherketone (PEK), polyetheretherketoneketone (PEEKK), etc., which are widely used in high-end equipment and daily necessities.

[0003] Compared with the most widely used PEEK material, PEK has fewer flexible groups in its molecular chain structure, which further improves its chain rigidity. Macroscopically, PEK has a higher glass transition temperature (Tg) and a higher melting point (Tm). This allows the long-term use temperature of PEK fiber-reinforced materials to reach above 300°C, a performance indicator that traditional PEEK materials cannot achieve. Due to the urgent demand for lightweight and high-temperature resistant components in fields such as aerospace, the localization of PEK resin is becoming increasingly urgent.

[0004] However, due to the high rigidity of PEK's molecular chain and the harsh ether-ketone alternating structure, its polymerization reaction has the characteristics of low activity and many side reactions. Most domestic companies and research institutes are still at the stage of laboratory trials. In the short term, PEK will still be one of the most difficult categories to industrialize in the polyaryletherketone family. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for preparing a polyetherketone resin. The technical solution of the present invention is as follows:

[0006] A method for preparing a polyetherketone resin comprises the following steps:

[0007] Using 4,4'-dihydroxybenzophenone and 4,4'-difluorobenzophenone as raw materials, diphenyl sulfone as solvent, and alkali metal carbonate as catalyst, a nucleophilic polycondensation reaction is carried out. The specific production process includes the following steps:

[0008] 1) Putting raw materials 4,4'-dihydroxybenzophenone, 4,4'-difluorobenzophenone and alkali metal carbonate into a reaction container, wherein the mole number of 4,4'-difluorobenzophenone is higher than the mole number of 4,4'-dihydroxybenzophenone, and adding molten diphenyl sulfone solvent under the condition of nitrogen or argon being introduced at 50-100 ml / min;

[0009] 2) The system temperature is maintained at 140-155°C, and stirring is continued for 60 minutes. When the raw materials in the reaction container are fully mixed, the temperature of the reaction container is raised to 200-220°C, and constant temperature stirring is performed for 60 minutes; then the temperature is raised to 240-290°C, and constant temperature stirring is performed for 60-150 minutes; then the temperature is raised to 310-330°C, and constant temperature stirring is performed for 60-150 minutes. During this process, nitrogen or argon gas at 150-200°C is introduced into the reaction container at a rate of 50-100 ml / min;

[0010] 3) When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding alkali metal salt of 4,4'-dihydroxybenzophenone or 4,4'-difluorobenzophenone;

[0011] 4) Finally, keeping other conditions unchanged, add a hydroxyl-free capping agent and stir for 30 to 60 minutes; then pour the reaction product into cold water, cool and solidify it, then crush it, wash it with alcohol and water to remove impurities, and dry it to obtain the PEK product.

[0012] Preferably, the molar number of the 4,4'-difluorobenzophenone is 1.01 to 1.20 times the molar number of the 4,4'-dihydroxybenzophenone.

[0013] Preferably, the mass of diphenyl sulfone is 2 to 4 times the sum of the masses of the 4,4'-dihydroxybenzophenone and the 4,4'-difluorobenzophenone.

[0014] Preferably, the alkali metal carbonate is one or both of sodium carbonate and potassium carbonate; and the amount thereof used is 1.15 to 1.25 times the molar number of 4,4'-dihydroxybenzophenone.

[0015] Preferably, the alkali metal salt of 4,4'-dihydroxybenzophenone is a dried potassium salt of 4,4'-dihydroxybenzophenone.

[0016] Preferably, the hydroxyl-free end-capping agent is 4-fluorobenzophenone or an end-capping agent mixture prepared by the following method:

[0017] Add diphenyl sulfone to a reaction system protected by nitrogen or argon, heat to 160°C, add 4-fluorobenzophenone and alkali metal carbonate, heat to 160°C, and add hydroquinone; heat the reaction system to 180°C-210°C for reaction for 30-120min; heat to 250°C for reaction for 30-60min, heat to 305°C for reaction for 30-60min, and obtain a liquid mixture, which is the end-capping agent mixed solution; wherein the molar ratio of 4-fluorobenzophenone:hydroquinone:alkali metal carbonate is 1:1:(1.05-1.25), and the mass ratio of 4-fluorobenzophenone to diphenyl sulfone is 1:18-1:2.

[0018] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50g / L, 170°C) was tested. The glass transition temperature of the product was 152±1°C, and the melting point was 370~375°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] Due to the high rigidity of PEK's molecular chain and its harsh ether-ketone alternating structure, its polymerization activity is low and reverse reaction is prone to occur.

[0021] 1) The protective gas in this application uses nitrogen or argon at 150~200℃, which can effectively prevent water vapor and diphenyl sulfone vapor from condensing into small droplets suspended in the reactor when encountering cold protective gas. These small droplets will further enrich water vapor and fall back into the system, resulting in insufficient removal of water in the system, which ultimately makes it difficult for the reaction to proceed in the forward direction.

[0022] 2) At the same time, the existing polyaryletherketone polymerization technology mostly uses the addition of dihydroxy monomers and difluoro monomers to adjust the molecular weight of the product. The addition of dihydroxy monomers will produce water molecules in the system, thereby hindering the forward reaction. This application uses alkali metal salts of 4,4'-dihydroxybenzophenone to replace traditional 4,4'-dihydroxybenzophenone, avoiding the generation of water molecules in the system.

[0023] 3) Finally, polyaryletherketone resin polymerization often uses an excessive amount of fluorinated monomers to better control the molecular weight of the product, and when the reaction tends to equilibrium and stagnates, the molecular weight end is mostly fluorine. In many cases, it is necessary to add a capping agent with a hydroxyl group at one end, which will lead to the generation of water molecules in this system. Therefore, adding 4-fluorobenzophenone or the capping agent mixture described in this patent according to the end group type of the reaction end point can avoid the generation of water molecules and avoid side reactions.

[0024] Through the above three technical points, the influence of water molecules on the reaction in the later stage of the reaction can be comprehensively reduced and avoided, the reaction efficiency can be improved, and side reactions can be reduced. At the same time, due to the particularity of PEK polymerization, the temperature section and temperature section time setting in this application are also consistent with PEK polymerization. DETAILED DESCRIPTION

[0025] The present invention is further described in detail through specific embodiments. Example 1

[0026] 400 mol of 4,4'-dihydroxybenzophenone, 408 mol of 4,4'-difluorobenzophenone, 456 mol of sodium carbonate and 24 mol of potassium carbonate were put into a reaction container, and 524.11 kg of molten diphenyl sulfone solvent was added while N2 was kept flowing at 90 ml / min;

[0027] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at a constant temperature for 60 min; then the temperature was raised to 245°C and stirred at a constant temperature for 150 min; then the temperature was raised to 320°C and stirred at a constant temperature for 60 min. During this process, N2 at 190°C was introduced into the reaction container at 90 ml / min.

[0028] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding 4,4'-difluorobenzophenone;

[0029] Finally, keeping other conditions unchanged, 4-fluorobenzophenone was added and stirred for 50 minutes; the reaction product was poured into cold water and cooled and solidified, then crushed, washed with alcohol and water to remove impurities, and dried to obtain the PEK product.

[0030] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1. Example 2

[0031] 400 mol of 4,4'-dihydroxybenzophenone, 420 mol of 4,4'-difluorobenzophenone, and 480 mol of sodium carbonate were placed in a reaction vessel, and 354.64 kg of molten diphenyl sulfone solvent was added while Ar was introduced at a rate of 90 ml / min;

[0032] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at constant temperature for 60 min; then the temperature was raised to 255°C and stirred at constant temperature for 150 min; then the temperature was raised to 320°C and stirred at constant temperature for 60 min. During this process, Ar at 190°C was introduced into the reaction container at 90 ml / min.

[0033] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding 4,4'-difluorobenzophenone;

[0034] Finally, keeping other conditions unchanged, 4-fluorobenzophenone was added and stirred for 50 minutes; the reaction product was poured into cold water and cooled and solidified, then crushed, washed with alcohol and water to remove impurities, and dried to obtain the PEK product.

[0035] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1. Example 3

[0036] 400 mol of 4,4'-dihydroxybenzophenone, 452 mol of 4,4'-difluorobenzophenone, 456 mol of sodium carbonate and 24 mol of potassium carbonate were placed in a reaction vessel, and 552.91 kg of molten diphenyl sulfone solvent was added while N2 was flowing at 95 ml / min;

[0037] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at a constant temperature for 60 min; then the temperature was raised to 245°C and stirred at a constant temperature for 150 min; then the temperature was raised to 320°C and stirred at a constant temperature for 60 min. During this process, N2 at 155°C was introduced into the reaction container at 95 ml / min.

[0038] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding dried sodium salt of 4,4'-dihydroxybenzophenone;

[0039] Finally, keeping other conditions unchanged, add the capping agent mixture and stir for 50 minutes; then pour the reaction product into cold water, cool and solidify it, then crush it, wash it with alcohol and water to remove impurities, and dry it to obtain the PEK product.

[0040] Preparation of capping agent mixture:

[0041] Add diphenyl sulfone to a nitrogen-protected reaction system, heat to 160° C., add 4-fluorobenzophenone and sodium carbonate, heat to 160° C., and add hydroquinone; heat the reaction system to 205° C. and react for 60 minutes; heat to 250° C. and react for 60 minutes; heat to 305° C. and react for 60 minutes, and the resulting liquid mixture is the end-capping agent mixed solution; wherein the molar ratio of 4-fluorobenzophenone:hydroquinone:sodium carbonate is 1:1:1.2, and the mass ratio of 4-fluorobenzophenone to diphenyl sulfone is 1:4.

[0042] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1. Example 4

[0043] 400 mol of 4,4'-dihydroxybenzophenone, 468 mol of 4,4'-difluorobenzophenone, 456 mol of sodium carbonate and 24 mol of potassium carbonate were placed in a reaction vessel, and 713.63 kg of molten diphenyl sulfone solvent was added while Ar was introduced at 90 ml / min.

[0044] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at constant temperature for 60 min; then the temperature was raised to 255°C and stirred at constant temperature for 150 min; then the temperature was raised to 320°C and stirred at constant temperature for 60 min. During this process, Ar at 170°C was introduced into the reaction container at 90 ml / min.

[0045] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding dried potassium salt of 4,4'-dihydroxybenzophenone;

[0046] Finally, keeping other conditions unchanged, add the capping agent mixture and stir for 50 minutes; then pour the reaction product into cold water, cool and solidify it, then crush it, wash it with alcohol and water to remove impurities, and dry it to obtain the PEK product.

[0047] Preparation of capping agent mixture:

[0048] Add diphenyl sulfone to a reaction system protected by argon, heat to 160° C., add 4-fluorobenzophenone and potassium carbonate, heat to 160° C., and add hydroquinone; heat the reaction system to 200° C. and react for 60 minutes; heat to 250° C. and react for 60 minutes; heat to 305° C. and react for 60 minutes, and the resulting liquid mixture is the end-capping agent mixed solution; wherein the molar ratio of 4-fluorobenzophenone:hydroquinone:potassium carbonate is 1:1:1.08, and the mass ratio of 4-fluorobenzophenone to diphenyl sulfone is 1:4.

[0049] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1. Comparative Example 1

[0050] 400 mol of 4,4'-dihydroxybenzophenone, 408 mol of 4,4'-difluorobenzophenone, 456 mol of sodium carbonate and 24 mol of potassium carbonate were put into a reaction container, and 524.11 kg of molten diphenyl sulfone solvent was added while N2 was kept flowing at 90 ml / min;

[0051] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at a constant temperature for 60 min; then the temperature was raised to 245°C and stirred at a constant temperature for 150 min; then the temperature was raised to 320°C and stirred at a constant temperature for 60 min. During this process, N2 at room temperature was introduced into the reaction container at 90 ml / min.

[0052] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding 4,4'-difluorobenzophenone;

[0053] Finally, keeping other conditions unchanged, 4-fluorobenzophenone was added and stirred for 50 minutes; the reaction product was poured into cold water and cooled and solidified, then crushed, washed with alcohol and water to remove impurities, and dried to obtain the PEK product.

[0054] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1. Comparative Example 2

[0055] 400 mol of 4,4'-dihydroxybenzophenone, 452 mol of 4,4'-difluorobenzophenone, 456 mol of sodium carbonate and 24 mol of potassium carbonate were placed in a reaction vessel, and 552.91 kg of molten diphenyl sulfone solvent was added while N2 was flowing at 95 ml / min;

[0056] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at a constant temperature for 60 min; then the temperature was raised to 245°C and stirred at a constant temperature for 150 min; then the temperature was raised to 320°C and stirred at a constant temperature for 60 min. During this process, N2 at 155°C was introduced into the reaction container at 95 ml / min.

[0057] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding dried 4,4'-dihydroxybenzophenone;

[0058] Finally, keeping other conditions unchanged, add the capping agent mixture and stir for 50 minutes; then pour the reaction product into cold water, cool and solidify it, then crush it, wash it with alcohol and water to remove impurities, and dry it to obtain the PEK product.

[0059] Preparation of capping agent mixture:

[0060] Add diphenyl sulfone to a nitrogen-protected reaction system, heat to 160° C., add 4-fluorobenzophenone and sodium carbonate, heat to 160° C., and add hydroquinone; heat the reaction system to 205° C. and react for 60 minutes; heat to 250° C. and react for 60 minutes; heat to 305° C. and react for 60 minutes, and the resulting liquid mixture is the end-capping agent mixed solution; wherein the molar ratio of 4-fluorobenzophenone:hydroquinone:sodium carbonate is 1:1:1.2, and the mass ratio of 4-fluorobenzophenone to diphenyl sulfone is 1:4.

[0061] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1. Comparative Example 3

[0062] 400 mol of 4,4'-dihydroxybenzophenone, 452 mol of 4,4'-difluorobenzophenone, 456 mol of sodium carbonate and 24 mol of potassium carbonate were placed in a reaction vessel, and 552.91 kg of molten diphenyl sulfone solvent was added while N2 was flowing at 95 ml / min;

[0063] The system temperature was maintained at 150°C and stirred continuously for 60 min. After the raw materials in the reaction container were fully mixed, the temperature of the reaction container was raised to 210°C and stirred at a constant temperature for 60 min; then the temperature was raised to 245°C and stirred at a constant temperature for 150 min; then the temperature was raised to 320°C and stirred at a constant temperature for 60 min. During this process, N2 at 155°C was introduced into the reaction container at 95 ml / min.

[0064] When the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding dried sodium salt of 4,4'-dihydroxybenzophenone;

[0065] Finally, keeping other conditions unchanged, 4-hydroxybenzophenone was added and stirred for 50 minutes; the reaction product was poured into cold water and cooled and solidified, then crushed, washed with alcohol and water to remove impurities, and dried to obtain the PEK product.

[0066] The Tg and Tm of the dried PEK product were measured by differential scanning calorimetry (DSC, heating rate 10°C / min, nitrogen atmosphere), and its solubility in m-chlorophenol (50 g / L, 170°C) was tested. The data are shown in Table 1.

[0067] Table 1

[0068]

[0069] By comparing the solubility of the product obtained in Example 1 with that in Comparative Example 1, it can be proved that a product with better solubility can be obtained by using nitrogen or argon at 150-200°C as a protective gas compared to a gas at room temperature. The poor solubility is caused by the structural defects caused by the side reactions from a microscopic perspective. It can be proved that the use of nitrogen or argon at 150-200°C as a protective gas can effectively improve the product quality. This is because nitrogen or argon at 150-200°C can effectively prevent water vapor and diphenyl sulfone vapor from condensing into small droplets suspended in the reactor when encountering cold protective gas. These small droplets will further enrich water vapor and fall back into the system, resulting in insufficient removal of water in the system, which ultimately makes it difficult for the reaction to proceed in the forward direction.

[0070] Comparing the solubility of the product obtained in Example 3 with that in Comparative Example 2, it can be proved that the addition of the hydroxyl-containing monomer will produce water molecules in the system, thereby hindering the forward reaction and causing reverse reactions and side reactions. This proves the superiority of replacing the traditional 4,4'-dihydroxybenzophenone with the alkali metal salt of 4,4'-dihydroxybenzophenone.

[0071] By comparing the solubility of the product obtained in Example 3 with that in Comparative Example 3, it can be proved that the presence of hydroxyl groups in the end-capping agent will also lead to the destruction of the molecular chain structure of the product.

[0072] In summary, by controlling the above three technical points, the influence of water molecules on the reaction in the later stage of the reaction can be comprehensively reduced and avoided, and the reaction efficiency can be effectively improved and side reactions can be reduced.

Claims

1. A method for preparing a polyetherketone resin, characterized in that: The following steps are involved: 1) Put the raw materials 4,4'-dihydroxybenzophenone, 4,4'-difluorobenzophenone and alkali metal carbonate into a reaction container, wherein the mole number of 4,4'-difluorobenzophenone is higher than the mole number of 4,4'-dihydroxybenzophenone, and add molten diphenyl sulfone solvent under the condition that nitrogen or argon is introduced at 50-100 ml / min; 2) Keep the system temperature at 140-155°C, stir continuously for 60 minutes, wait for the raw materials in the reaction container to be fully mixed, heat the reaction container to 200-220°C, stir at constant temperature for 60 minutes; then heat it to 240-290°C, stir at constant temperature for 60-150 minutes; then heat it to 310-330°C, stir at constant temperature for 60-150 minutes, during this process, keep nitrogen or argon at 150-200°C at 50-100 ml / min into the reaction vessel; 3) when the reaction tends to stagnate, keep other conditions unchanged, and adjust the molecular weight of the resin by adding alkali metal salt of 4,4'-dihydroxybenzophenone or 4,4'-difluorobenzophenone; 4) finally, keep other conditions unchanged, add a hydroxyl-free end-capping agent and stir for 30-60 minutes; then pour the reaction product into cold water, cool and solidify, then crush it, wash with alcohol and water to remove impurities, and dry to obtain the PEK product.

2. The method for preparing a polyetherketone resin according to claim 1, characterized in that: The molar number of the 4,4'-difluorobenzophenone is 1.01 to 1.20 times the molar number of the 4,4'-dihydroxybenzophenone.

3. The method for preparing a polyetherketone resin according to claim 1, characterized in that: The mass of diphenyl sulfone is 2 to 4 times the sum of the masses of the 4,4'-dihydroxybenzophenone and the 4,4'-difluorobenzophenone.

4. The method for preparing a polyetherketone resin according to claim 1, characterized in that: The alkali metal carbonate is one or both of sodium carbonate and potassium carbonate; and the amount used is 1.15 to 1.25 times the molar number of 4,4'-dihydroxybenzophenone.

5. The method for preparing a polyetherketone resin according to claim 1, characterized in that: The alkali metal salt of 4,4'-dihydroxybenzophenone is a dried potassium salt of 4,4'-dihydroxybenzophenone.

6. The method for preparing a polyetherketone resin according to claim 1, characterized in that: The hydroxyl-free end-capping agent is 4-fluorobenzophenone or an end-capping agent mixed solution prepared by the following method: adding diphenyl sulfone to a reaction system protected by nitrogen or argon, heating to 160°C, adding 4-fluorobenzophenone and alkali metal carbonate, heating to 160°C, and adding hydroquinone; heating the reaction system to 180°C-210°C for reaction for 30-120min; heating to 250°C for reaction for 30-60min, heating to 305°C for reaction for 30-60min, and the resulting liquid mixture is the end-capping agent mixed solution; wherein the molar ratio of 4-fluorobenzophenone:hydroquinone:alkali metal carbonate is 1:1:(1.05-1.25), and the mass ratio of 4-fluorobenzophenone to diphenyl sulfone is 1:18-1:

2.

7. The resin prepared by the method for preparing a polyetherketone resin according to claim 1, characterized in that The glass transition temperature of the resin is 152±1°C and the melting point is 370~375°C.

8. The resin according to claim 7, characterized in that The resin can be dissolved in m-chlorophenol at a concentration of 50 g / L at 170°C.

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