A kind of amine-modified macroporous resin, polycarbonate with low urethane content and preparation method thereof

Abstract

The present invention relates to a method for continuously preparing polycarbonate in a two-phase interface method. The catalyst used in preparing the polycarbonate is an amine-modified macroporous resin, and the preparation monomers thereof include polyvinylbenzene monomers, double-bond monomers containing amine groups, and allyl gamma-cyclodextrin, which can produce polycarbonate with low carbamate, and preferably the total nitrogen content of the polycarbonate is less than 10ppm. Such a catalytic resin can save the separation-recovery unit of the catalyst in engineering, and the cyclodextrin structure can de-emulsify the emulsified oil-water two phases when the working condition is abnormal, so that the reaction process and the oil-water separation process proceed normally.

Description

Technical Field

[0001] The invention relates to the preparation of polycarbonate, in particular to a method for continuously preparing polycarbonate by using an amine-modified macroporous resin solid-phase catalytic two-phase interface method. Background Art

[0002] The two-phase interface method has been widely used in the preparation of polycarbonate, and the polycarbonate obtained by this method can be used in many fields, such as data carriers, optically transparent sheets, products in the automotive glass industry, or thermoplastic polycarbonate for medical applications. Trace amounts of metal elements in polycarbonate often have a significant impact on transparency and processing, and can cause the sheet to turn yellow, so reducing the residual metal elements is also an important issue in the production process of polycarbonate.

[0003] The preparation of polycarbonate by the two-phase interface method usually uses tertiary amine as a homogeneous catalyst. During the reaction, a byproduct of a terminal amino formate structure is generated, which will lead to the formation of defective structures and thus lead to the degradation of the quality of carrier materials and optical materials of optical storage media such as CDs and DVDs. At the same time, the homogeneous catalyst needs to be separated and recovered in the process. Chinese invention patent CN 100349954C uses a reactor configuration of a circulating pump reactor with an additional retention tube, and does not make the molar ratio of catalyst to bisphenol less than 0.012 to 0.05 during the polymerization process. The nitrogen content of the polycarbonate finally obtained is about 10 to 20 ppm. Chinese patent CN 101128509 B provides a process parameter, and the total nitrogen content of the obtained polycarbonate is between 6 and 60 ppm, which is prepared by using an excess of phosgene of 8 to 17 mol% based on the total amount of bisphenol used, wherein the pH value of the aqueous phase is maintained in the alkaline range during and after the addition of phosgene, and after the addition of the catalyst, the pH value is adjusted to 10 to 14, and the temperature during the phosgenation is 0°C to 40°C. However, during the implementation of this method, a slight fluctuation in the phosgene feed rate can cause the total nitrogen content to increase by 3 to 6 times. Considering the cost of catalyst recycling and the abnormal operating conditions of oil-water emulsification that often occur during the reaction, a new process needs to be developed. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing polycarbonate by solid phase catalysis. The present invention is a new method for preparing polycarbonate by solid phase catalysis in interfacial polymerization, the most prominent advantage of which is that the catalyst does not need to be separated and recovered, and abnormal emulsification conditions can be eliminated.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides an amine-modified macroporous resin.

[0007] The amine-modified macroporous resin of the present invention is prepared by suspension polymerization technology, that is, raw materials including double-bond monomers containing amine groups, polyvinylbenzene, allyl γ-cyclodextrin and porogen are placed in a reactor, and then an optional free radical initiator is added to the reactor. After a certain reaction time (for example, reaction at 60-80° C. for 0.5-8 hours), the porogen is washed away and dried to obtain the macroporous resin modified with amine groups and γ-cyclodextrin.

[0008] Specifically, the steps of the amine-modified macroporous resin are:

[0009] 1) preparing the oil phase at room temperature: uniformly mixing polyvinylbenzene monomer, double bond monomer containing amine group, allyl γ-cyclodextrin, porogen, and optional free radical initiator;

[0010] 2) Prepare the aqueous phase at room temperature: mix deionized water, dispersant, and optional dispersing aid uniformly,

[0011] 3) Then the oil phase and the water phase are mixed to carry out polymerization reaction, the polymerization temperature is 70-95°C, the polymerization time is 4-8h, and mechanical stirring is used during the reaction process.

[0012] In the preparation method of the macroporous resin, in step 1), the polyvinylbenzene can be selected from one or more of divinylbenzene, substituted divinylbenzene, trivinylbenzene, and substituted trivinylbenzene. The substituted divinylbenzene and substituted trivinylbenzene can be 2-methyl-1,4-divinylbenzene, 2-methoxy-1,4-divinylbenzene, 2-ethyl-1,4-divinylbenzene, 2,3-dimethyl-1,4-divinylbenzene, 2-methyl-1,3,5-trivinylbenzene, and 2-methoxy-1,3,5-trivinylbenzene.

[0013] The double bond monomer containing an amine group is usually dimethylaminoethyl methacrylate and / or diethylaminoethyl methacrylate;

[0014] Allyl-γ-cyclodextrin can be prepared by Williamson ether synthesis from 3-chloropropylene and γ-cyclodextrin sodium salt;

[0015] The free radical initiator can be selected from one or more of organic peroxides, such as dibenzoyl peroxide, cumene hydroperoxide; azo initiators, such as azobisisobutyronitrile, azobisisoheptanenitrile, etc.;

[0016] The porogen can be selected from one or more of n-hexane, benzene, toluene, xylene, pentane, n-heptane, chlorobenzene, dichlorobenzene, dichloromethane, ether, propylene oxide, petroleum ether, methyl acetate, ethyl acetate, butanone, 3# white oil, 5# white oil, etc.;

[0017] In the preparation of the amine-modified macroporous resin, the mass ratio of polyvinylbenzene to the double-bond monomer containing an amine group can be 1:0.2 to 5, preferably 1:0.2 to 0.8;

[0018] The mass ratio of allyl-γ-cyclodextrin to polyvinylbenzene is 0.1 to 0.9, preferably 0.2 to 0.6.

[0019] The amount of free radical initiator is 0.01-0.5wt% of the total amount of monomers (the sum of the weight of amino double bond monomers, allyl-γ-cyclodextrin and polyvinylbenzene), preferably 0.05-0.2wt%.

[0020] The amount of the porogen used is 10 to 60 wt % of the total amount of the monomers.

[0021] In the preparation method of the macroporous resin, in step 2), the dispersant is selected from one or more mixtures of polyvinyl alcohol, gelatin, hydroxypropyl methylcellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose, preferably polyvinyl alcohol and / or hydroxyethyl cellulose, and the amount of the dispersant is 0.02-0.5wt.% of the mass of the aqueous phase, preferably 0.1-0.3wt.% of the mass of the aqueous phase.

[0022] The dispersing aid is one or more of sodium chloride, magnesium chloride, potassium chloride and calcium chloride, and the dispersing aid accounts for 1-10wt.% of the mass of the water phase.

[0023] In the preparation method of the macroporous resin, in step 3), the mass ratio of the oil phase to the water phase is 1:5 to 1:2, the macroporous resin obtained by the reaction is washed with acetone at 40 to 70°C, preferably at about 70°C for 4 to 8 hours, and after washing, it is vacuum dried at 40 to 70°C, preferably at about 60°C to obtain an amine-modified macroporous resin. The amine-modified macroporous resin can be put into use after being infiltrated with dichloromethane.

[0024] Preferably, the BET specific surface area of ​​the macroporous resin is 200 to 1000 m 2 / g.

[0025] The second aspect of the present invention provides the use of the above-mentioned amino-modified macroporous resin in the solid-phase catalytic preparation of polycarbonate.

[0026] The method for preparing polycarbonate comprises: filling an amine-modified macroporous resin into a polymerization reactor, introducing a prepolymerized circulating reaction liquid, passing through the resin in sequence and being catalyzed, ensuring that the circulating reaction liquid and the catalytic resin have sufficient contact time, the contact time is 10 to 50 minutes, and preferably the contact time is 20 to 40 minutes.

[0027] In the method for preparing polycarbonate, the prepolymerized circulating reaction liquid can be prepared by the following process: add 1 part by mass of deionized water, 0.06-0.10 parts by mass of sodium hydroxide, 0.20-0.25 parts by mass of bisphenol A and 0.005-0.010 parts by mass of end-capping agent to a glass kettle. Purge the glass kettle with nitrogen and start mechanical stirring. After stirring and mixing evenly, the prepared aqueous phase, a total of 1.5-2.0 parts by mass of oil phase and a total of 0.11-0.15 parts by mass of phosgene are introduced into the buffer tank at a certain speed. During the whole process, concentrated alkali solution is continuously added dropwise to control the pH of the aqueous phase between 11 and 13. The residence time of phosgene and bisphenol A in the buffer tank is 10-30 minutes. The effluent is the prepolymerized circulating liquid;

[0028] The end-capping agent may be one or more of p-tert-butylphenol, phenol, p-cumylphenol, cresol, p-phenylphenol, p-chlorophenol, tribromocresol and pentabromophenol;

[0029] The oil phase may be one or more of dichloromethane, chloroform, monochlorobenzene and o-dichlorobenzene;

[0030] The concentrated alkali solution is, for example, a sodium hydroxide solution with a mass fraction of 32%.

[0031] When the prepolymerized circulating reaction liquid passes through the polymerization reactor, the contact time between the PC reaction liquid and the amino-modified macroporous resin is preferably maintained at 20 minutes to 40 minutes, and the temperature of the reaction liquid during contact is between 30 and 40°C.

[0032] Amine-modified macroporous resin replaces traditional organic amine and quaternary ammonium salt homogeneous catalysts. After the polymerization reaction is completed, the reaction solution is washed with acid and deionized water in sequence, and finally polycarbonate is prepared after drying.

[0033] The polycarbonate prepared by the method of the present invention contains a carbamate derivative of the general formula (1) with a total nitrogen content of less than 10 ppm;

[0034]

[0035] in

[0036] R1 and R2 are independent of each other and represent hydrogen or C1-C10-alkyl, or

[0037] R1 and R2 together represent C4-C10 homoalkylene.

[0038] R3 and R4 independently represent hydrogen, C1-C10-alkyl, or phenyl, or

[0039] R3 and R4 together with the carbon atoms to which they are bonded form a cyclohexyl group or a trimethylcyclohexyl group,

[0040] R5 represents hydrogen, C1-C10-alkyl, C5-C10-cycloalkyl or phenyl.

[0041] Advantages of the present invention: The present invention adopts solid-phase catalysis, does not need to separate and recover the catalyst separately, can eliminate abnormal emulsification conditions, and finally prepares polycarbonate with low nitrogen content. DETAILED DESCRIPTION

[0042] The present invention is illustrated by the following examples, but the scope of the present invention is not limited to these examples.

[0043] The BET specific surface area of ​​the amine-modified macroporous resin was obtained using Micromeritics ASAP2460M, and the nitrogen content was measured using an elemental analysis tester (EA3000, Euro Vector, Italy).

[0044] The nitrogen content of polycarbonate was obtained by nuclear magnetic resonance (NMR) using a Bruker AVANCE III 400M NMR test. The terminal amide structure content was first calculated by NMR and then converted into total nitrogen content.

[0045] The molecular weight of polycarbonate was obtained by Agilent Technologies 1260infinity test, with dichloromethane as the mobile phase, a flow rate of 1 mL / min, and the column temperature and the box temperature were both 30°C.

[0046] Preparation method of allyl-γ-cyclodextrin:

[0047] Weigh 25 g of γ-cyclodextrin and dissolve it in 200 mL of dimethylformamide, then add 2 g of sodium hydride, stir at room temperature for 0.5 to 2 h and filter, add 7.5 mL of 3-chloropropylene to the filtrate, raise the temperature to 60°C, and continue the reflux reaction for 18 to 24 h; after the reaction is completed, pour the reaction solution into methanol to precipitate allyl-γ-cyclodextrin solid, filter, dry and set aside.

[0048] Example 1

[0049] At room temperature, add the premixed aqueous phase into a four-necked flask, the composition of which is: 520.7 g of deionized water, 16.2 g of sodium chloride, 2.2 g of polyvinyl alcohol, and 1 g of 0.1 wt.% methylene blue aqueous solution. Start stirring and raise the temperature to 50°C.

[0050] Turn off stirring and add the premixed oil phase, the composition of which is: 35.9 g of dimethylaminoethyl methacrylate, 35.9 g of divinylbenzene, 17.9 g of allyl-γ-cyclodextrin, 5.6 g of toluene, 44.8 g of 3# white oil, and 0.45 g of dibenzoyl peroxide.

[0051] Stirring was started. The temperature was raised to 70°C and kept constant for 8 hours. After the reaction was completed, polymer beads were obtained. The polymer beads were washed with water and then eluted with acetone as solvent at 60°C for 8 hours to obtain a microporous precursor, which was then vacuum dried at 60°C for 6 hours and infiltrated with dichloromethane to obtain an amine-modified macroporous resin.

[0052] The particle size of the microporous precursor is 200-1200 μm, and the BET specific surface area is 600 m 2 / g, according to element analysis, the N content is 3.02%.

[0053] Preparation of prepolymerized circulating reaction liquid: Add 6153g of deionized water, 492g of sodium hydroxide, 1400g of bisphenol A and 36.3g of p-tert-butylphenol to a glass kettle. Purge the glass kettle with nitrogen and start mechanical stirring. After stirring and mixing evenly, introduce the prepared water phase, 10152g of dichloromethane and 714g of phosgene into the buffer tank at a certain speed. During the whole process, add concentrated alkali solution continuously to control the pH of the water phase between 11 and 13. The residence time of phosgene and bisphenol A in the buffer tank is 10min.

[0054] 5L of the above catalytic adsorption resin was loaded into the tubular reactor of the PC phosgenation polymerization reaction section, and the prepolymerized circulating reaction liquid flowed through the macroporous resin at 250mL / min, and the contact time with the resin was 20min, and the temperature of the tubular reactor was maintained at 33°C. The reaction liquid flowing out of the macroporous resin was successively washed with 0.2M hydrochloric acid and deionized water, and finally the polycarbonate powder was obtained after drying.

[0055] According to NMR calculation, the total nitrogen content of the obtained powder is 4.2ppm.

[0056] Example 2-4 Synthesis of amine-modified macroporous resin

[0057] At room temperature, add the premixed aqueous phase into a four-necked flask, the composition of which is: 510.4 g of deionized water, 27.0 g of potassium chloride, 1.7 g of hydroxyethyl cellulose, and 1 g of 0.1 wt.% methylene blue aqueous solution. Start stirring and raise the temperature to 50°C.

[0058] Turn off the stirring and add the premixed oil phase, which is composed of 80.0 g of dimethylaminoethyl methacrylate and divinylbenzene, 9.7 g of allyl-γ-cyclodextrin, 5.6 g of xylene, 44.8 g of 3# white oil, and 0.50 g of azobisisobutyronitrile.

[0059] Start stirring. Raise the temperature to 80°C and keep the temperature constant for 6 hours. After the reaction is completed, polymer beads are obtained. After the polymer beads are washed with water, leached with acetone as solvent at 70°C for 6 hours to obtain a microporous precursor, which is then vacuum dried at 70°C for 5 hours and infiltrated with dichloromethane to obtain an amine-modified macroporous resin.

[0060] The masses of dimethylaminoethyl methacrylate and 2-methyl-1,4-divinylbenzene in Example 2-4, and the properties of the prepared resin are shown in Table 1.

[0061] Table 1. Parameters of amine-modified macroporous resins

[0062]

[0063] Embodiment 5-7

[0064] Effect of Amine-Modified Macroporous Resins on Catalysis of PC Polymerization

[0065] Preparation of prepolymerized circulating reaction liquid: 6768g of deionized water, 474g of sodium hydroxide, 1540g of bisphenol A and 56.6g of p-cumylphenol were added to a glass kettle. Nitrogen was purged into the glass kettle, and mechanical stirring was turned on. After stirring and mixing evenly, the prepared water phase, 10828g of o-dichlorobenzene and 785g of phosgene were introduced into the buffer tank at a certain speed. During the whole process, concentrated alkali solution was continuously added dropwise to control the pH of the water phase between 11 and 13. The residence time of phosgene and bisphenol A in the buffer tank was 10 minutes.

[0066] 5L of the amino-modified macroporous resin obtained in Examples 2-4 above were respectively loaded into the tubular reactor of the PC phosgenation polymerization reaction section, and the oil-water mixed prepolymerization reaction liquid flowed through the macroporous resin at 250mL / min, and the contact time with the resin was 25min, and the temperature of the tubular reactor was maintained at 33°C. The reaction liquid flowing out of the macroporous resin was successively washed with 0.2M hydrochloric acid and deionized water, and finally a polycarbonate powder was obtained after drying.

[0067] The total nitrogen content of the obtained powder is shown in Table 2.

[0068] Table 2. Test results of PC reaction solution and PC powder obtained

[0069]

Claims

1. A method for preparing polycarbonate, comprising: The amine-modified macroporous resin is filled into a polymerization reactor, and the prepolymerized circulating reaction liquid is introduced, and the contact time between the circulating reaction liquid and the resin is 10 to 50 minutes; The preparation method of the amine-modified macroporous resin comprises: 1) preparing the oil phase: uniformly mixing the polyvinylbenzene monomer, the double bond monomer containing an amine group, the allyl γ-cyclodextrin, the porogen, and the optional free radical initiator; 2) preparing the aqueous phase: uniformly mixing water, a dispersant and an optional dispersing aid; 3) The oil phase and the water phase are mixed to carry out polymerization reaction.

2. The method according to claim 1, wherein: The mass ratio of polyvinylbenzene to the double bond monomer containing an amine group is 1:0.2-5; and / or The mass ratio of allyl-γ-cyclodextrin to polyvinylbenzene is 0.1 to 0.9; and / or The amount of free radical initiator used is 0.01-0.5 wt% of the total amount of monomers (the sum of the weight of the amino double bond monomer, allyl-γ-cyclodextrin and polyvinylbenzene); and / or The amount of the porogen used is 10 to 60 wt % of the total amount of the monomers.

3. The method according to claim 1 or 2, wherein: The polyvinylbenzene is selected from one or more of divinylbenzene, substituted divinylbenzene, trivinylbenzene, and substituted trivinylbenzene; The substituted divinylbenzene and substituted trivinylbenzene are selected from 2-methyl-1,4-divinylbenzene, 2-methoxy-1,4-divinylbenzene, 2-ethyl-1,4-divinylbenzene, 2,3-dimethyl-1,4-divinylbenzene, 2-methyl-1,3,5-trivinylbenzene, 2-methoxy-1,3,5-trivinylbenzene.

4. The method according to any one of claims 1 to 2, wherein: The double bond monomer containing an amine group is dimethylaminoethyl methacrylate and / or diethylaminoethyl methacrylate.

5. The method according to any one of claims 1 to 2, wherein: The free radical initiator is selected from one or more of organic peroxides and azo initiators; The porogen is selected from one or more of n-hexane, benzene, toluene, xylene, pentane, n-heptane, chlorobenzene, dichlorobenzene, dichloromethane, ether, propylene oxide, petroleum ether, methyl acetate, ethyl acetate, butanone, 3# white oil, and 5# white oil.

6. The method according to any one of claims 1 to 2, wherein: The dispersant is selected from one or more of polyvinyl alcohol, gelatin, hydroxypropyl methylcellulose, hydroxyethyl cellulose, and hydroxypropyl cellulose.

7. The method according to claim 6, wherein: The amount of dispersant used accounts for 0.02 to 0.5 wt.% of the mass of the water phase.

8. The method according to any one of claims 1 to 2, wherein: The dispersing aid is one or more of sodium chloride, magnesium chloride, potassium chloride and calcium chloride.

9. The method according to claim 8, wherein: The dispersing aid accounts for 1 to 10 wt.% of the mass of the water phase.

10. The method according to any one of claims 1 to 2, wherein: The mass ratio of oil phase to water phase is 1:5 to 1:2, the polymerization temperature is 70 to 95°C, and the polymerization time is 4 to 8 hours.

11. The method according to claim 1, wherein: The prepolymerized circulating reaction liquid comprises: 1 part by mass of deionized water, 0.06-0.10 parts by mass of sodium hydroxide, 0.20-0.25 parts by mass of bisphenol A, 0.005-0.010 parts by mass of a capping agent, 1.5-2.0 parts by mass of an oil phase and 0.11-0.15 parts by mass of phosgene.

12. The method according to claim 11, wherein: The end-capping agent is one or more of p-tert-butylphenol, phenol, p-cumylphenol, cresol, p-phenylphenol, p-chlorophenol, tribromocresol and pentabromophenol; The oil phase is one or more of dichloromethane, chloroform, monochlorobenzene and o-dichlorobenzene.

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