CN115058009A - 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 content of cyclic polymer. The method comprises the following steps: (1) putting bisphenol monomer, dichlorodiphenyl sulfone, pre-polymerization alkali and catalyst into a solvent according to a proportion, and carrying out pre-polymerization reaction under the condition of high solid content; (2) adding a polymerization base and a diluting solvent to carry out polymerization reaction, and simultaneously evaporating the aqueous solvent; (3) and (4) precipitating, washing and drying the polymer solution to obtain the finished resin. The invention adopts two-stage polymerization, improves the solid content of the fed material in the prepolymerization stage, and reduces the amount of the cyclopolymer generated in the initial stage by using a special polymerization catalyst system, thereby finally obtaining the sulfone polymer product with low cyclopolymer content. The implementation method adopted by the invention is simple and easy, has wide raw material sources and low requirements on equipment, and has better economic benefit.

Description

Preparation method of sulfone polymer with low cyclic polymer content

Technical Field

The invention belongs to the field of synthesis of high molecular polymers, and particularly 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 sulfone 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.

The production process of sulfone polymer is characterized by that according to traditional preparation method, mainly using bisphenol monomer and dichloro monomer to make stepwise polymerization in strong polar aprotic solvent under the condition of high-temp. alkali environment to obtain polymer solution, then making a series of post-treatment processes of desalting, precipitation and washing to obtain polymer powder material, finally making extrusion and granulation so as to obtain the finished product resin. During the polymerization, the formation of the bisphenol salt is promoted under the environment of strong alkali, and then nucleophilic substitution reaction is carried out with the aromatic halogen. In this process, it is inevitable to induce a portion of the prepolymer to undergo a self-cyclization reaction to form a small molecular ring. The cyclic dimer has higher melting point and poorer solubility, and the transparency of a product is easily influenced by crystallization in the melt extrusion molding process, so that the yarn breakage problem is caused in the spinning process. (S.Savariar, G.S.Underwood, E.M.Dickinson, desalinization, 144(2002) 15-20). Therefore, how to reduce the generation of cyclic dimers is an important issue in this field.

CN111253574A discloses a polysulfone synthesis method by slowly adding dichlorodiphenyl sulfone at a constant speed to reduce cyclic dimer. In the method, the end capping agent and part of the dichloro monomer solution are added at a constant speed for reaction in a water-carrying stage, so that the content of the cyclic dimer is reduced by about 35-36%. However, the method has higher requirements on the process operation of constant-speed feeding, and the final content of the cyclic dimer of the 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 dimethyl acetamide as solvent, half amount of solvent and dichloro monomer are added at the beginning of reaction, after water separation and salt formation are finished, the other half amount of dichloro monomer solution is added dropwise into subsequent reaction polymerization, and finally the resin with low cyclic dimer content is obtained. The method has the defects that the dripping operation is complicated and difficult to control, and the method needs a large amount of water removing agent (half of the mass of the dimethylacetamide) and has the water dividing time of 8 hours, so that 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 that addresses the various deficiencies of the existing methods.

Disclosure of Invention

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

The method comprises the following steps:

(1) putting a bisphenol monomer, a dihalogen monomer dihalogen diphenyl sulfone, a pre-polymerization base and a catalyst into a solvent according to a proportion, and carrying out pre-polymerization reaction under the condition of high solid content;

(2) adding a polymerization base and a diluting solvent to carry out polymerization reaction, and simultaneously evaporating the aqueous solvent;

(3) and (4) precipitating, 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 dihalodiphenyl sulfone is preferably dichlorodiphenyl sulfone;

when bisphenol A and dichlorodiphenyl sulfone are used as polymerization monomers, the final product is polysulfone resin. Similarly, when bisphenol S is substituted for bisphenol a, a polyethersulfone resin is ultimately obtained, and when biphenol is substituted for bisphenol a, a polyphenylsulfone resin is ultimately obtained. The method is applicable to the three resins or any copolymerized 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 reason for maintaining the slightly excessive double-halogen monomer is to ensure that the polymerization reaction can be automatically terminated due to the excessive chlorine end groups in the later synthesis stage, and the end capping by adding an end capping agent additionally due to the excessive phenol can be avoided, so that the preparation process is simplified;

in the step (1) of the invention, the initial reaction charge solid content is set to be 38-45%, preferably 40-42%. In the traditional preparation process, the initial solid content is generally more common according to 20-25 percent of feeding. However, researches show that in the prepolymerization stage, the phenol oxyanion with lower concentration is subjected to intramolecular cyclization reaction, while the phenol oxyanion with higher concentration is more prone to intermolecular nucleophilic reaction, so that the method is favorable for reducing the formation of cyclic dimer in the prepolymerization stage by improving the initial solid content;

in step (1) of the present invention, the pre-polymeric base is an inorganic weak base, including but not limited to sodium bicarbonate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, preferably sodium bicarbonate. The reason why the inorganic weak base is adopted is that the reaction rates of intramolecular cyclization and intermolecular polymerization of phenoxides are relatively close under the strong base condition, while the reaction rate of the phenoxides is lower than that of the phenoxides under the weak base environment, so that the probability of cyclization reaction can be reduced through the competitive reaction under the weak base environment. In the present invention, the amount of the pre-polymerization base added is 50 to 90%, preferably 60 to 80%, based on the molar amount of the bisphenol monomer. Within this range, a large proportion of the phenolic hydroxyl groups are converted into linear oligomers immediately after salification, and the remaining unreacted monomers can further participate in the chain extension polymerization in the polymerization stage. It is to be noted that, since the prepolymer base is weak in basicity and the reaction equilibrium exists so that the total phenolic hydroxyl groups are not sufficiently converted into salts even if a larger amount is charged, the amount thereof is suitably within the above range;

in the step (1) of the present invention, the catalyst is a mixture of the component A and the component B. Wherein, the component A is an organic metal compound, including but not limited to palladium acetate, palladium dichloride, rhodium trichloride and rhodium triiodide, and the component B is an aprotic organic nitrogen-containing heterocyclic compound, including but not limited to urotropine, triazole, pyridine, pyrimidine and pyrazine. Here, component A functions as a catalyst for nucleophilic reactions, increasing 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 provided by the invention on intermolecular prepolymerization reaction in a weak base environment is higher than that of intramolecular cyclization reaction;

wherein the input amount of the catalyst component A is 0.05-0.5%, preferably 0.1-0.4% of the mass of the bisphenol monomer, and the input amount of the catalyst component B is 1-10%, preferably 5-8% of the mass of the bisphenol monomer. It should be noted that, because the alkalescence of the pre-polymerization base is weak, the capability of itself for exciting the nucleophilic substitution reaction is not strong, if the catalytic system of the present invention is not used, or only one of the components is used alone, or the amount of the above components is reduced, the reaction effect of the pre-polymerization stage cannot be well completed, and even the 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 is 2.1 to 2.8 times, preferably 2.2 to 2.4 times, the molar amount of the metal atom in the polymeric base molecule is the molar amount of the bisphenol monomer. 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 phenolic hydroxyl groups are consumed by the prepolymerization in the first stage, the concentration of the remaining diphenol monomer is decreased by the dilution of the system, and the possibility of generating cyclic dimer is further decreased, mainly linear polymerization.

In the step (2), the addition amount of the diluting solvent is 0.2-1.0 times of the initial solvent input amount. The necessity of diluting the solvent is: the solid content of initial feeding is higher, the viscosity of the system is obviously increased by lower solid content after the prepolymerization stage, and the viscosity is increased more rapidly along with the increase of molecular weight in the polymerization stage. If the solid content is still high, stirring mass transfer difficulty is easily caused and even gelation is easily caused. Therefore, proper dilution and viscosity reduction are required in the polymerization stage.

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

In the steps (1) and (2), the reaction temperature in the step (1) is 80-150 ℃, preferably 100-140 ℃, and the reaction time is 1-5 hours. With the catalytic system according to the invention, the intermolecular chain growth selectively occurs rapidly even in a weakly basic environment, and intramolecular cyclization is correspondingly suppressed, so that the overall time does not need to be too long. And (3) carrying out the polymerization reaction in the step (2) at a reflux temperature for 2-4 hours. During the reaction, a small amount of the aqueous solvent needs to be distilled off to promote the reaction equilibrium toward the formation of ether bonds. Generally, this can be achieved by rectification systems known to the skilled worker, which allow higher degrees of polymerization to be achieved in the end product when the water content distilled off exceeds 80% of theory.

The polymerization reaction endpoint can be judged by various modes such as observation of stirring torque, system viscosity, sampling test and the like, and the judgment standard that a certain index does not change any more is taken as a judgment standard.

Through the steps (1) and (2), the invention can finally obtain the sulfone polymer product with low cyclic dimer content, wherein the cyclic dimer content is as low as 0-0.5 wt%.

The subsequent treatment of the step (3) of the invention comprises the following specific steps: and pouring the polymer reaction solution into a precipitating agent under the condition of stirring for precipitation, then filtering, washing for 2-4 times by using a detergent, and finally drying to obtain a polysulfone finished product. The precipitating agent and the detergent are one or more of water, methanol and ethanol, and ethanol is preferably used. The present invention is not particularly limited to specific embodiments of each step of the post-treatment including equipment, process conditions, and the like, and the advantageous effects caused by the present invention are not affected by a change in the general treatment manner. In particular, since the present invention has previously adopted the condition of excess chlorine monomer, the blocking agent and the blocking step required in the conventional process are not necessary.

The invention has at least the following positive effects:

(1) weak base is adopted to be matched with a special catalytic system, so that the generation of cyclic dimer is inhibited in the prepolymerization stage, and the content of the cyclic dimer in the final product can be as low as 0-0.5 wt%;

(2) according to the invention, polymerization reaction is carried out according to excessive chlorine monomer, so that excessive unstable hydroxyl residue is avoided, the introduction of an end-capping reagent is avoided, and the process is simplified;

(3) the method has the advantages of 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 solution, the following embodiments are given, which are not intended to limit the scope of the present invention.

GPC measurement method: shimadzu LC-20A liquid chromatograph

A detector: ultraviolet absorption detector

Light source: SPD-20A D2 lamp

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

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

The infusion mode is as follows: tandem double plunger

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

The water content measuring method comprises the following steps: metler C20S moisture tester

Karl Fischer's method, three measurements are taken and the average value is determined.

The reagents used in the examples are all commercially available.

Example 1

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

666.25g of N, N-dimethylacetamide and 329g of potassium carbonate were then added, the mixture was heated to reflux and reacted for 4 hours, during which the aqueous solvent was gradually removed through a rectification column, and the stirring torque was finally observed not to rise by a further 32g of water, 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 for 3 times by using ethanol, and drying to obtain a polysulfone resin product.

Example 2

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

113.28g of dimethylformamide and 102g of sodium hydroxide were added, the mixture was heated to reflux and reacted for 3 hours, during which time the aqueous solvent was gradually discharged through the rectifying column, and the viscosity did not rise any more in terms of 16.6g of water, indicating that the polymerization was completed. Pouring the polymer solution into a full-phase mixer while the polymer solution is hot, crushing and separating out, washing for 3 times by using 50% ethanol water solution, and drying to obtain a polyether sulfone resin product.

Example 3

657.81g of sulfolane was poured into a reaction kettle equipped with a condenser tube, a rectifying column, a water separator, a mechanical stirrer and a thermometer, and preheated to 80 ℃ to melt it sufficiently. 181.5g of biphenol, 287.16g of dichlorodiphenyl sulfone, 74.1g of sodium bicarbonate, 0.907g of rhodium triiodide and 2g of triazole are added, and prepolymerization reaction is carried out at 150 ℃ for 4 hours.

And (3) after the prepolymerization reaction is finished, properly cooling, then adding 652g of sulfolane and 149g of potassium carbonate, continuously heating to reflux, gradually rectifying to obtain a water-containing solvent, and stopping after the reaction is carried out for 2 hours, wherein the water content is reduced to 17 g. And crushing and separating out the polymer solution by using a crushing pump, washing for 4 times by using boiling water, and drying to obtain the polyphenylsulfone resin product.

Example 4

3079.48g N, N-dimethylacetamide was poured into an oil bath reactor connected with a condenser, a rectifying and water-separating device, a mechanical stirrer with torque monitoring and a thermometer, and 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 were poured under stirring. The reaction kettle is heated to 130 ℃ for reaction for 5 hours.

1847.69g of dimethylacetamide and 588g of potassium hydroxide are added, the reaction is stopped when the torque is not increased after the temperature is increased to reflux and the reaction is carried out for 2 hours, and the aqueous solvent is rectified during the reaction, and the water content is reduced to 88.4 g. And crushing and separating out the polymer solution by using a crushing pump, refluxing and washing for 3 times by using ethanol, and drying to obtain a polysulfone resin product.

Example 5

2665g 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 were added to a closed reaction kettle connected with a condenser tube, a rectification and water separation device, a mechanical stirrer with torque monitoring and a thermometer. The system was warmed to 120 ℃ and reacted for 4 h.

Then 2132g N, N-dimethylacetamide and 657g of potassium carbonate were added, heating was continued to reflux and the aqueous solvent was distilled off, amounting to 69g of water. The reaction was stopped for about 4h until the torque no longer rose. And crushing and separating out the polymer solution by using a crushing pump, washing for 2 times by using ethanol in a refluxing manner, washing for 2 times by using water, and drying to obtain a polysulfone resin product.

Comparative example 1:

the traditional polysulfone production process is adopted for implementation.

13393.5g N, N-dimethylacetamide was added to a reaction vessel equipped with 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 vessel was slowly warmed to reflux temperature under nitrogen blanket and allowed to react for 10h, during which time aqueous solvent was gradually taken off, amounting to 171g of water. And introducing methyl chloride or ethyl chloride for end capping after the reaction is finished, and keeping for about 30 min. And (3) crushing and separating out the finally obtained polymer mucus by using a crushing pump, boiling and washing the polymer mucus for 6 times by using water, and drying the polymer mucus to obtain a polysulfone resin product.

Comparative example 2:

the reaction was carried out as in example 1 except that no catalytic component consisting of palladium acetate and urotropin was added. Finally, the reaction system has low viscosity, the weight average molecular weight of precipitates does not exceed 2000 in GPC test, and the product has no practical value.

GPC of the products of examples 1 to 5 and comparative example 1 gave the following results:

compared with the traditional production process, the sulfone polymer prepared by the invention has obviously lower cyclic dimer content and has outstanding inherent advantages in specific application.

Claims (10)

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

(1) mixing a bisphenol monomer, a dihalogen monomer dihalogen diphenyl sulfone, a pre-polymeric alkali, a catalyst and a solvent, and carrying out pre-polymeric reaction under the condition of high solid content;

(2) adding a polymerization base and a diluting solvent to carry out polymerization reaction, and simultaneously evaporating the aqueous solvent;

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

2. The method according to claim 1, wherein the bisphenol monomer in step (1) is selected from the group consisting of bisphenol A, bisphenol S, biphenol;

the dihalo diphenyl sulfone is dichloro diphenyl sulfone;

preferably, the molar ratio of bisphenol monomer to dihalogen monomer is (0.980-0.999): 1, more preferably (0.990-0.998): 1.

3. The method according to any one of claims 1-2, wherein the high solids condition in step (1) means that the feed solids content is 38-45%, preferably 40-42%.

4. The method according to any one of claims 1 to 3, wherein the solvent in step (1) is one or more selected from the group consisting of dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dimethylsulfoxide, trichlorobenzene and sulfolane.

5. The preparation method according to any one of claims 1 to 4, wherein the pre-polymeric base in step (1) is an inorganic weak base, preferably one or more of sodium bicarbonate, sodium dihydrogen phosphate and potassium dihydrogen phosphate;

preferably, the input amount of the pre-polymeric alkali is 50-90% of the molar amount of the bisphenol monomer.

6. The production method according to any one of claims 1 to 5, wherein the catalyst in step (1) is a mixture of component A and component B; wherein, the component A is an organic metal compound, including but not limited to one or more of palladium acetate, palladium dichloride, rhodium trichloride and rhodium triiodide, and the component B is an aprotic organic nitrogen-containing heterocyclic compound, including but not limited to one or more of urotropine, triazole, pyridine, pyrimidine and pyrazine;

preferably, the input amount of the component A is 0.05-0.5% of the mass of the bisphenol monomer, and the input amount of the component B is 1-10% of the mass of the bisphenol monomer.

7. The method according to any one of claims 1 to 6, wherein the prepolymerization reaction temperature in step (1) is 80 to 150 ℃ and the reaction time is 1 to 5 hours.

8. The method according to any one of claims 1 to 7, wherein the polymeric base in the step (2) is one or more of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide;

preferably, the amount of the polymeric base is 2.1 to 2.8 times of the molar amount of the bisphenol monomer in the polymeric base molecule.

9. The production method according to any one of claims 1 to 8, wherein the amount of the diluting solvent added in the step (2) is 0.2 to 1.0 times the amount of the initially charged solvent.

10. The method according to any one of claims 1 to 9, wherein the polymerization in the step (2) is carried out at a reflux temperature for 2 to 4 hours.