CN115058009B - Preparation method of sulfone polymer with low cyclic polymer content - Google Patents

Abstract

The invention provides a preparation method of a sulfone polymer with low cyclic polymer content. The method comprises the following steps: (1) Bisphenol monomer, dichlorodiphenyl sulfone, pre-polymerization alkali and catalyst are added into solvent according to proportion, and pre-polymerization reaction is carried out under the condition of high solid content; (2) Adding polymeric alkali and a diluting solvent to carry out polymerization reaction, and evaporating the water-containing solvent at the same time; (3) And separating out, washing and drying the polymer solution to obtain the finished resin. According to the invention, through adopting two-stage polymerization, the solid content of the fed material is improved in the pre-polymerization stage, and the amount of cyclic polymer generated in the initial stage is reduced by using a special polymerization catalytic system, so that the sulfone polymer product with low cyclic polymer content is finally obtained. The implementation method adopted by the invention is simple and easy to implement, has wide sources of raw materials, low requirements on equipment and better economic benefit.

Description

Preparation method of sulfone polymer with low cyclic polymer content

Technical Field

The invention belongs to the field of high molecular polymer synthesis, and in particular relates to a preparation method of a sulfone polymer with low cyclic polymer content.

Technical Field

The sulfone polymer is a high temperature resistant engineering plastic containing sulfonyl characteristic groups, and generally comprises polysulfone, polyphenylsulfone and polyethersulfone. The sulfone polymer has wide application prospect in the fields of high-end electronics, water treatment, medical consumables, aviation materials and the like according to the outstanding thermal stability, mechanical property and dielectric property.

According to the traditional preparation method, bisphenol monomers and dichloro monomers are subjected to gradual polymerization in a strong polar aprotic solvent through nucleophilic reaction in a high-temperature alkali environment to generate a polymer solution, and then a series of post-treatment procedures such as desalting, precipitation, washing and the like are carried out to obtain polymer powder, and finally extrusion granulation is carried out to obtain the finished product resin. In the polymerization process, it is generally required to promote the formation of bisphenolate under a strong alkaline environment, and then to carry out nucleophilic substitution reaction with aromatic halogen. In the process, partial prepolymer is not induced to undergo self-cyclization reaction to form a small molecule cyclic body. The cyclic dimer has higher melting point and poorer solubility, and is extremely easy to influence the transparency of a product due to crystallization in the process of melt extrusion molding, and the problem of yarn breakage is caused in the spinning process. (S.Savariar, G.S.Underwood, E.M.Dickinson, desalination,144 (2002) 15-20). Therefore, how to reduce the generation of cyclic dimers is an important topic in this field.

CN111253574a discloses a polysulfone synthesis method by slowly adding dichlorodiphenyl sulfone at a uniform speed, thereby reducing cyclic dimer. The method reduces the cyclic dimer content by about 35-36% by adding the end-capping agent and part of the dichloro monomer solution into the reaction at a constant speed in the water-carrying stage. However, the method has higher requirement on the process operation of constant-speed feeding, and the cyclic dimer content of the final polysulfone is still higher and reaches 1.1-1.2 wt%.

CN110527094a discloses a method for preparing polysulfone resin with low dimer content by adding dichloro monomer step by step. The method adopts potassium carbonate as acid-binding base and dimethylacetamide as solvent, half of the solvent and dichloro monomer are added in the beginning of the reaction, after water separation and salification are finished, the other half of dichloro monomer solution is added into the subsequent reaction polymerization by dripping, and finally the resin with low cyclodimer content is obtained. The method has the defects that firstly, the dripping operation is complicated and difficult to control, secondly, the method needs a large amount of water scavenger (half of the mass of dimethylacetamide), the water diversion time is 8 hours, and the production economic benefit is poor.

In view of the above, there is a need in the art to find a new method for reducing cyclic dimers to address the various drawbacks of the existing methods.

Disclosure of Invention

The invention provides a preparation method of a low-cyclic polymer content sulfone polymer. The method adopts a prepolymerization and polymerization two-stage reaction. In the prepolymerization stage, a special catalytic system is adopted under the high solid content condition, so that the initial generation probability of the cyclodimer is reduced; chain growth is realized in the polymerization stage, and finally, a qualified resin product with low cyclic dimer content is obtained.

The method comprises the following steps:

(1) Bisphenol monomer, dihalogen monomer dihalogen diphenyl sulfone, pre-polymerization alkali and catalyst are added into solvent according to proportion, and pre-polymerization reaction is carried out under the condition of high solid content;

(2) Adding polymeric alkali and a diluting solvent to carry out polymerization reaction, and evaporating the water-containing solvent at the same time;

(3) And separating out, washing and drying the polymer solution to obtain the finished resin.

In the step (1), the bisphenol monomer is bisphenol A, bisphenol S or biphenol;

the dihalodiphenylsulfone is preferably dichlorodiphenyl sulfone;

when bisphenol A and dichlorodiphenyl sulfone are used as polymerization monomers, polysulfone resin is finally obtained. Similarly, when bisphenol A is replaced with bisphenol S, a polyethersulfone resin is finally obtained, and when bisphenol A is replaced with biphenol, a polyphenylsulfone resin is finally obtained. The method is applicable to the three resins or any copolymer resin of the three resins;

in the step (1) of the present invention, the molar ratio of the bisphenol monomer to the dihalogen monomer is (0.980 to 0.999): 1, preferably (0.990 to 0.998): 1. The purpose of maintaining a slight excess of dihalogen monomer is to ensure that the polymerization reaction can be automatically terminated due to the excess of chlorine end groups in the later stage of synthesis, and the need of adding an end capping agent for capping due to the excess of phenol can be avoided, thereby simplifying the preparation process;

in the step (1) of the invention, the solid content of the initial reaction feed is set to be 38-45%, preferably 40-42%. Under the traditional preparation process, the initial solid content is generally common in the process of feeding according to 20-25%. However, it has been found that in the pre-polymerization salt formation stage, a lower concentration of oxyanion is transactionally subject to intramolecular cyclization, while a higher concentration of oxyanion is more prone to intermolecular nucleophilic reaction, thus the method of the present invention is advantageous for reducing the formation of cyclic dimers in the pre-polymerization stage by increasing the initial solids content;

in the step (1) of the present invention, the pre-polymer base is an inorganic weak base, including, but not limited to, sodium bicarbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, preferably sodium bicarbonate. The reason for adopting inorganic weak base is that under the condition of strong base, the reaction rate of intramolecular cyclization and intermolecular polymerization of the phenoxyl salt is relatively close, and under the condition of weak base, the reaction rate of the phenoxyl salt is lower than that of the phenoxyl salt, so that the probability of cyclization reaction can be reduced through competition reaction under the condition of weak base. In the present invention, the amount of the pre-polymer base to be added is 50 to 90% by mole, preferably 60 to 80% by mole, of the bisphenol monomer. Within this amount, most of the phenolic hydroxyl groups are salified and immediately converted into linear oligomers, and the remaining unreacted monomers can further participate in the chain extension polymerization during the polymerization stage. It is to be noted that since the alkali of the prepolymer base is weak, the reaction equilibrium exists such that even a larger amount is not enough to convert all of the phenolic hydroxyl groups into salts, and thus the amount thereof is suitable within the above-mentioned range;

in the step (1) of the present invention, the catalyst is a mixture of the component A and the component B. Wherein component A is an organometallic compound including, but not limited to, palladium acetate, palladium dichloride, rhodium trichloride, rhodium triiodide, and component B is an aprotic organic nitrogen-containing heterocyclic compound including, but not limited to, urotropine, triazole, pyridine, pyrimidine, pyrazine. Here, the component A acts as a catalyst for nucleophilic reaction to increase the reaction rate; the component B is used as an electron donor, can reduce the reaction energy barrier, and also plays a role in promoting the prepolymerization reaction and reducing the prepolymerization time. Practice shows that the catalytic effect of the catalytic system for intermolecular prepolymerization reaction in weak base environment is higher than that of intramolecular cyclization reaction;

wherein the dosage of the catalyst component A is 0.05 to 0.5 percent, preferably 0.1 to 0.4 percent, of the mass of the bisphenol monomer, and the dosage of the catalyst component B is 1 to 10 percent, preferably 5 to 8 percent, of the mass of the bisphenol monomer. In particular, the weak alkalinity of the pre-polymerized alkali has weak capability of exciting nucleophilic substitution reaction, and if the catalytic system is not adopted, or only one component is adopted singly, or the dosage is reduced, the reaction effect of the pre-polymerization stage cannot be completed well, and even nucleophilic reaction is difficult to occur.

In the step (2) of the present invention, the polymeric base is one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide, preferably potassium carbonate. The amount of the polymeric base used is 2.1 to 2.8 times, preferably 2.2 to 2.4 times, the molar amount of the metal atoms in the polymeric base molecule relative to the bisphenol monomers. In this case, strong alkali is used to accelerate the polymerization rate in the later stage and to increase the polymerization degree of the final product. At this time, since most of the phenolic hydroxyl groups are consumed by the prepolymerization reaction in the first stage, the concentration of the remaining diphenol monomers decreases after the dilution of the system, and the possibility of producing cyclic dimers is further reduced, mainly in the case of linear polymerization.

In the step (2), the addition amount of the diluting solvent is 0.2 to 1.0 times the amount of the initially introduced solvent. The necessity of a diluting solvent is: the viscosity of the system rises more obviously after the prepolymerization stage due to the higher solid content of the initial charge, and the viscosity rises more rapidly with the increase of the molecular weight in the polymerization stage. If the solid-state catalyst is still in a high solid-state, stirring mass transfer is extremely difficult and gel is even caused. It is therefore necessary to dilute the viscosity appropriately during the polymerization stage.

The solvent in the steps (1) and (2) can be one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, trichlorobenzene and sulfolane, preferably dimethylacetamide.

In the steps (1) and (2) of the present invention, the reaction temperature of the step (1) is 80 to 150 ℃, preferably 100 to 140 ℃, and the reaction time is 1 to 5 hours. Under the catalytic system according to the invention, the intermolecular chain growth can selectively take place rapidly even in a weak alkaline environment, while the intramolecular cyclization is correspondingly inhibited, so that the overall time is not too long. The polymerization reaction in the step (2) is carried out at a reflux temperature for 2 to 4 hours. During the reaction, a small amount of the aqueous solvent needs to be distilled off to promote the reaction equilibrium to the ether bond formation direction. In general, this can be achieved by means of rectification systems known to the skilled worker, with the end product achieving a higher degree of polymerization when the distilled off moisture content exceeds 80% of theory.

The polymerization reaction end point can be judged by observing stirring torque, system viscosity, sampling test and other modes, and certain index is not changed any more to be a judging standard.

By the above steps (1) and (2), the present invention finally gives a low cyclic dimer content sulfone polymer product having a cyclic dimer content as low as 0 to 0.5% by weight.

The subsequent treatment specific steps of the step (3) are as follows: pouring the polymer reaction liquid into a separating agent to separate out under the stirring condition, filtering, washing for 2-4 times by using a detergent, and finally drying to obtain a polysulfone finished product. The precipitating agent and the washing agent are one or more of water, methanol and ethanol, and ethanol is preferable. The invention is not particularly limited to the particular embodiments of the various steps of the post-treatment, including equipment, process conditions, etc., and variations in the general manner of treatment do not affect the advantageous effects of the invention. In particular, since the present invention has previously adopted the condition of excess chlorine monomer, the capping agent and the capping step required for the conventional process are not necessary.

The invention has at least the following positive effects:

(1) The weak base is matched with a special catalytic system to inhibit the generation of cyclodimers in the prepolymerization stage, and the content of the cyclodimers of the final product can be as low as 0-0.5 wt%;

(2) According to the invention, the polymerization reaction is carried out according to the excessive chlorine monomer, so that excessive unstable hydroxyl residues are avoided, the introduction of a blocking agent is avoided, and the process is simplified;

(3) The invention has simple and clear operation, few working procedures, high process operation flexibility, no special requirements on equipment and easy popularization.

Detailed Description

According to the technical scheme, the following examples are given, and the examples are not used for limiting the protection scope of the invention.

GPC test method: shimadzu LC-20A liquid chromatograph

A detector: ultraviolet absorption detector

Light source: SPD-20A D2 lamp

Wavelength range: SPD-20A 190nm-700nm

Flow setting range: 0.001mL/min-10.000mL/min

The transfusion mode is as follows: tandem double plunger

The sample preparation method comprises the following steps: 1% THF solution

The method for measuring the moisture comprises the following steps: metreler C20S moisture tester

The karl fischer method was used to measure the average three times.

The reagents used in the examples are all commercially available.

Example 1

Into a reactor connected with a condenser, a rectifying column, a water separator, a mechanical stirrer (with a torque monitoring device) and a thermometer, 1332.5g of N, N-dimethylacetamide was poured, and 452g of bisphenol A, 574.32g of dichlorodiphenyl sulfone, 161.67g of potassium dihydrogen phosphate, and a catalyst composed of 0.452g of palladium acetate and 36g of urotropine were poured while stirring. The temperature was rapidly raised and stabilized to 140 ℃ for 2h of reaction.

Then, 666.25g of N, N-dimethylacetamide and 329g of potassium carbonate were continuously added, the temperature was raised to reflux and the reaction was carried out for 4 hours, during which time the aqueous solvent was gradually discharged through the rectification column, the water content was reduced to 32g, and finally, the stirring torque was observed not to rise any more, indicating the completion of the polymerization. Pouring the polymer solution into a full-phase mixer while the polymer solution is hot, crushing and separating out, washing with ethanol for 3 times, and drying to obtain the polysulfone resin product.

Example 2

566.41g of N, N-dimethylformamide, 245.26g of bisphenol S, 287.16g of dichlorodiphenyl sulfone, 94.05g of sodium dihydrogen phosphate, 0.981g of palladium dichloride and 25g of pyrimidine were poured into a four-necked flask connected with a condenser, a rectifying column, a water separator, a mechanical stirrer and a thermometer while stirring. The flask was warmed to 80℃and reacted for 3h.

Then 113.28g of dimethylformamide and 102g of sodium hydroxide were added, the temperature was raised to reflux and the reaction was carried out for 3 hours, during which time the aqueous solvent was gradually discharged through the rectification column, reducing the water content to 16.6g, and the viscosity was no longer increased, indicating the end of the polymerization. Pouring the polymer solution into a full-phase mixer while the polymer solution is hot, crushing and separating out, washing the polymer solution with 50% ethanol water solution for 3 times, and drying the polymer solution to obtain the polyethersulfone resin product.

Example 3

657.81g of sulfolane is poured into a reaction kettle connected with a condensing tube, a rectifying column, a water separator, a mechanical stirrer and a thermometer, and preheated to 80 ℃ to be fully melted. 181.5g of biphenol, 287.16g of dichlorodiphenyl sulfone, 74.1g of sodium hydrogen carbonate, 0.907g of rhodium triiodide and 2g of triazole were further added, and the prepolymerization was carried out at 150℃for 4 hours.

After the prepolymerization reaction is finished, the temperature is properly reduced, 652g of sulfolane and 149g of potassium carbonate are added, the temperature is continuously increased to reflux, the water-containing solvent is gradually rectified, the water content is reduced by 17g, and the reaction is stopped after 2 hours. And (3) crushing the polymer solution by a crushing pump to separate out, washing the polymer solution with boiling water for 4 times, and drying the polymer solution to obtain the polyphenylsulfone resin product.

Example 4

3079.48g of N, N-dimethylacetamide, 1139.17g of bisphenol A, 1435.8g of dichlorodiphenyl sulfone, 339.54g of potassium dihydrogen phosphate, 0.57g of palladium dichloride and 57g of urotropine are poured into an oil bath reaction kettle which is connected with a condenser tube, a rectifying water distributing device, a mechanical stirrer with torque monitoring and a thermometer. The reaction kettle is heated to 130 ℃ for reaction for 5 hours.

Then 1847.69g of dimethylacetamide and 588g of potassium hydroxide are added, the reaction is stopped after the temperature is raised to reflux and the torque is not increased after the reaction for 2 hours, the aqueous solvent is distilled off during the period, and the water content is reduced to 88.4g. And (3) crushing the polymer solution by a crushing pump to separate out, refluxing and washing the polymer solution by ethanol for 3 times, and drying the polymer solution to obtain the polysulfone resin product.

Example 5

2665g of N, N-dimethylacetamide, 904.03g of bisphenol A, 1148.64g of dichlorodiphenyl sulfone, 323.35g of potassium dihydrogen phosphate and a catalytic component consisting of 3.616g of palladium acetate and 72g of urotropine are added into a closed reaction kettle which is connected with a condenser tube, a rectifying water-distributing device, a mechanical stirrer with torque monitoring and a thermometer. The system was heated to 120℃and reacted for 4h.

Then 2132g of N, N-dimethylacetamide and 657g of potassium carbonate are added, heating is continued to reflux and the aqueous solvent is distilled off, which amounts to 69g of water. The reaction was stopped for about 4 hours until the torque was no longer rising. And (3) crushing the polymer solution by a crushing pump to separate out, refluxing and washing for 2 times by ethanol, washing for 2 times by water, and drying to obtain the polysulfone resin product.

Comparative example 1:

the method is implemented by adopting the traditional polysulfone production process.

13393.5g of N, N-dimethylacetamide was introduced into a reaction vessel connected to a condenser, a water separator, mechanical stirring and a thermometer, and 2305.7g of bisphenol A, 2871.6g of dichlorodiphenyl sulfone and 1659g of potassium carbonate were gradually added under stirring. The reaction kettle is slowly heated to reflux temperature under the protection of nitrogen, the reaction is continued for 10 hours, and the water-containing solvent is gradually taken out during the reaction, so that 171g of water is formed. And after the reaction is finished, introducing chloromethane or chloroethane for end capping for about 30min. And (3) crushing and separating out the finally obtained polymer mucus by using a crushing pump, boiling and washing for 6 times by using water, and drying to obtain the polysulfone resin product.

Comparative example 2:

the reaction was carried out in the same manner as in example 1 except that the catalytic component consisting of palladium acetate and urotropine was not added. The final experiment shows that the viscosity of the reaction system is very low, the weight average molecular weight of the precipitate is not more than 2000 in GPC test, and the product has no practical value.

The products of examples 1 to 5 and comparative example 1 were subjected to GPC test to obtain the following results:

it is evident from comparison that the sulfone polymers produced in accordance with the present invention have significantly lower cyclic dimer content than conventional production processes and will have outstanding innate advantages in specific applications.

Claims (13)

1. A method for preparing a sulfone polymer having a low cyclic polymer content comprising the steps of:

(1) Mixing bisphenol monomer, dihalogen monomer dihalogen diphenyl sulfone, pre-polymerized alkali and catalyst with solvent, and carrying out pre-polymerization under high solid content condition;

the mole ratio of bisphenol monomer to dihalogen monomer is (0.980-0.999): 1; the catalyst is a mixture of a component A and a component B, wherein the component A is an organic metal compound, the organic metal compound comprises one or more of palladium acetate, palladium dichloride, rhodium trichloride and rhodium triiodide, the component B is an aprotic organic nitrogen-containing heterocyclic compound, and the aprotic organic nitrogen-containing heterocyclic compound comprises one or more of urotropine, triazole, pyridine, pyrimidine and pyrazine;

(2) Adding polymeric alkali and a diluting solvent to carry out polymerization reaction, and evaporating the water-containing solvent at the same time;

(3) And (3) carrying out post-treatment on the polymer solution to obtain the sulfone polymer resin.

2. The process according to claim 1, wherein the bisphenol monomer in step (1) is selected from bisphenol a, bisphenol S, biphenol;

the dihalogenated diphenyl sulfone is dichloro diphenyl sulfone;

the molar ratio of bisphenol monomer to dihalogen monomer is (0.990-0.998): 1.

3. The method according to claim 1, wherein the high solid content condition in the step (1) means that the solid content of the feed is 38-45%.

4. The method according to claim 3, wherein the high solid content condition in the step (1) means that the solid content of the feed is 40-42%.

5. The process according to any one of claims 1 to 4, wherein the solvent in step (1) is one or more of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, trichlorobenzene, sulfolane.

6. The process according to any one of claims 1 to 4, wherein the pre-polymerized base in step (1) is an inorganic weak base;

the input amount of the pre-polymerized alkali is 50-90% of the mole amount of bisphenol monomers.

7. The method according to claim 6, wherein the pre-polymer base in the step (1) is one or more of sodium bicarbonate, sodium dihydrogen phosphate and potassium dihydrogen phosphate.

8. The method according to claim 1, wherein in the step (1), the amount of the component A added is 0.05 to 0.5% by mass of the bisphenol monomer, and the amount of the component B added is 1 to 10% by mass of the bisphenol monomer.

9. The preparation method according to any one of claims 1 to 4 and 8, wherein the prepolymerization reaction temperature in the step (1) is 80 to 150 ℃ and the reaction time is 1 to 5 hours.

10. The method according to claim 1, wherein the polymeric base in the step (2) is one or more of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide.

11. The method according to claim 10, wherein in the step (2), the amount of the polymeric base is 2.1 to 2.8 times the molar amount of the bisphenol monomer to the metal atom in the polymeric base molecule.

12. The method according to claim 1, wherein the amount of the diluent solvent added in the step (2) is 0.2 to 1.0 times the amount of the initially charged solvent.

13. The process according to any one of claims 1, 10 to 12, wherein the polymerization in step (2) is carried out at reflux temperature for a reaction time of 2 to 4 hours.