Polysiloxane end-capped modified copolycarbonate and preparation method thereof
阅读说明：本技术 一种聚硅氧烷封端改性的共聚碳酸酯及其制备方法 (Polysiloxane end-capped modified copolycarbonate and preparation method thereof ) 是由 魏志涛 王磊 曾伟 张珏 黎雷 李凤闯 于 2021-10-09 设计创作，主要内容包括：本发明公开了一种聚硅氧烷封端改性的共聚碳酸酯及其制备方法,所述共聚碳酸酯包含聚碳酸酯链段以及位于分子链中间的聚硅氧烷链段和位于分子链末端的聚硅氧烷链段,可以实现在聚硅氧烷总添加量不变的情况下得到同时具有优异的阻燃性能、耐化学性能以及低温抗冲击性能的改性共聚碳酸酯材料。(The invention discloses polysiloxane-terminated modified copolycarbonate and a preparation method thereof, wherein the copolycarbonate comprises a polycarbonate chain segment, a polysiloxane chain segment positioned in the middle of a molecular chain and a polysiloxane chain segment positioned at the tail end of the molecular chain, so that a modified copolycarbonate material with excellent flame retardant property, chemical resistance and low-temperature impact resistance can be obtained under the condition that the total addition amount of polysiloxane is not changed.)
1. A polysiloxane end-capped modified copolycarbonate, wherein said copolycarbonate comprises at least segments of the structures of formula I, formula II, and formula III:
in the formula II, the first step is carried out,represents a linking site with other segments; m is an integer of 10 to 100, preferably 20 to 50; r1 is C1-C6 alkyl, preferably C2-C4 alkyl; r2 is an alkyleneoxy group having from C1 to C6, preferably from C2 to C4; a is an ester bond or a carbonate bond;
in the formula III, n is an integer of 20-150, preferably an integer of 40-90.
2. The polysiloxane end-capped modified copolycarbonate according to claim 1, wherein the weight percentage of the segment represented by formula i is 50 to 90%, preferably 60 to 95%, the weight percentage of the segment represented by formula ii is 1 to 10%, preferably 4 to 10%, and the weight percentage of the segment represented by formula iii is 1 to 40%, preferably 1 to 30%.
3. The polysiloxane end-capped modified copolycarbonate according to claim 1 or 2, wherein the weight average molecular weight of the copolycarbonate is 18000 to 50000g/mol, preferably 22000 to 35000 g/mol.
4. A method of preparing the polysiloxane end-capped modified copolycarbonate according to any one of claims 1 to 3, comprising the steps of:
1) continuously adding reaction raw materials of phosgene, BPA phenol sodium salt water solution, PDMS monomer solution and inert organic solvent into a polymerization reactor R-1 for photochemical reaction;
2) continuously conveying the oligomer emulsion in the polymerization reactor R-1 to a polymerization reactor R-2, and simultaneously adding a single-end reaction active PDMS monomer solution for copolymerization reaction;
3) continuously conveying the copolymerization reaction liquid to a polymerization reactor R-3, and continuously adding a capping agent solution and a catalyst solution to perform polycondensation;
4) continuously conveying the polycondensation reaction liquid to a polymerization reactor R-4 until the polycondensation reaction is completed, and continuously conveying the polymer solution to a storage tank D-1;
5) and purifying the polymer solution, removing the organic solvent, and collecting to obtain the copolycarbonate.
5. The method for preparing polysiloxane end-capped modified copolycarbonate according to claim 4, wherein the pH of the reaction solution is controlled to be 11 to 12, preferably 11.5 to 11.7, by adding an aqueous solution of alkali metal hydroxide during the reaction in each step;
preferably, the alkali metal hydroxide is selected from one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide, cesium hydroxide, preferably sodium hydroxide.
6. The method for preparing a polysiloxane end-capped modified copolycarbonate according to claim 4, wherein in each step, the reaction residence time in each polymerization reactor is 10 to 30min, preferably 10 to 15 min;
preferably, the reaction temperature in each polymerization reactor in each step is independently 30 to 35 ℃.
7. The method for preparing the polysiloxane end-capped modified copolycarbonate according to any one of claims 4 to 6, wherein in step 1), the molar ratio of phosgene to BPA phenol sodium salt is (1.01 to 1.3) to 1, preferably (1.1 to 1.15) to 1; the amount of the PDMS monomer is 0.01-0.8 time of the mass of BPA with the molar quantity equal to that of BPA phenolic sodium salt in the step 1).
8. The method of claim 7, wherein in step 2), the amount of the single-end reaction-active PDMS monomer is 0.01 to 0.2 times the amount of BPA in an equimolar amount to BPA phenolic sodium salt in step 1).
9. The method for preparing the polysiloxane end-capped modified copolycarbonate according to claim 8, wherein in the step 3), the amount of the end-capping reagent is (20-40): 1, preferably (27-30): 1; the dosage of the catalyst is (160-10000): 1, preferably (200-1000): 1 based on the molar ratio of the BPA phenol sodium salt to the catalyst;
preferably, the end-capping agent is one or more of phenol, p-cumylphenol, p-methylphenol, p-isopropylphenol, p-tert-butylphenol and p-cyanophenol, preferably one or two of p-tert-butylphenol and p-cyanophenol; the catalyst is one or more of triethylamine, tetrabutylammonium bromide and tetrabutylammonium chloride, and triethylamine is preferred.
10. The method for preparing the polysiloxane end-capped modified copolycarbonate according to any one of claims 4 to 6, wherein the structural expression of the single-ended reactive PDMS monomer is as shown in formula IV:
in the formula IV, m is an integer of 10-100, preferably an integer of 20-50; r1 is C1-C6 alkyl, preferably C2-C4 alkyl; r2 is an alkyleneoxy group having from C1 to C6, preferably from C2 to C4; r3 is selected from hydroxy or carboxy;
preferably, the structural expression of the PDMS monomer is shown in formula v:
in the formula V, n is an integer of 20-150, preferably 40-90.
Technical Field
The invention relates to copolycarbonate and a preparation method thereof, in particular to polysiloxane end-capped modified copolycarbonate and a preparation method thereof, and belongs to the technical field of high polymer materials.
Background
Polycarbonate (PC) is a high molecular polymer containing a carbonate bond in its molecular chain, and can be classified into aliphatic, alicyclic, aliphatic-aromatic and aromatic polycarbonates, wherein aromatic polycarbonates have excellent mechanical properties, heat resistance, impact toughness, electrical insulation, light transmittance, creep resistance, low water absorption, good dimensional stability, excellent dielectric properties, and the like, and thus can be widely applied to the fields of automobiles, electronic equipment, buildings, office supplies, optical disks, sports equipment, medical care, computers, aerospace, and the like. However, conventional aromatic polycarbonates have certain disadvantages, such as relatively poor intrinsic flame retardancy (a 3mm sample only reaches a V2 rating), poor solvent resistance, easy occurrence of stress cracking after exposure to a solvent, poor impact properties at low temperatures, limitation of applications in low-temperature locations, and the like, and need to be modified in order to broaden the application fields thereof.
An intrinsic flame-retardant copolymerized PC and a preparation method thereof are disclosed in patent CN112898553A, bisphenol S and a siloxane chain segment are introduced into a conventional PC molecular chain to improve the intrinsic flame-retardant property of the PC, the highest flame-retardant energy level of the PC can reach UL94V0(3mm), but the low-temperature impact resistance and the chemical resistance of the material are to be further improved; CN105849171B discloses a method for preparing a train interior component with low smoke and low heat release, wherein a polymerization end is synthesized into cyanophenol end-capped branched PC, tetrabromobisphenol A copolymerized PC and siloxane PC, the branched PC, tetrabromobisphenol A copolymerized PC and siloxane PC are blended with conventional PC, flame retardant and other additives according to a certain proportion, the flame retardant is separated out when the blending is carried out, and the mechanical property of the material is influenced, namely the comprehensive use performance of the material is influenced.
In conclusion, it is necessary to research a new copolycarbonate product capable of improving intrinsic flame retardant properties, chemical resistance, impact resistance, etc. of polycarbonate resin to make up for the disadvantages of conventional polycarbonate and to broaden the application fields of polycarbonate materials.
Disclosure of Invention
In order to solve the technical problems, the invention provides polysiloxane end-capped modified copolycarbonate and a preparation method thereof. The linear structure of the copolycarbonate contains polysiloxane chain segments positioned in the middle of a molecular chain and polysiloxane chain segments positioned at the tail ends of the molecular chain. The polysiloxane chain segment positioned in the middle of the molecular chain is beneficial to improving the low-temperature impact resistance of the copolymer, and the polysiloxane chain segment positioned at the tail end of the molecular chain is beneficial to improving the flame retardant property and the chemical resistance of the copolymer, so that the modified copolycarbonate material with excellent flame retardant property, chemical resistance and low-temperature impact resistance can be obtained under the condition that the total addition amount of polysiloxane is not changed.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a polysiloxane end-capped modified copolycarbonate, said copolycarbonate comprising at least segments of the structures of formula I, formula II, and formula III:
in the formula II, the first step is carried out,represents a linking site with other segments; m is an integer of 10 to 100, preferably 20 to 50; r1 is C1-C6 alkyl, preferably C2-C4 alkyl; r2 is an alkyleneoxy group having from C1 to C6, preferably from C2 to C4; a is an ester bond or a carbonate bond;
in the formula III, n is an integer of 20-150, preferably an integer of 40-90.
In some examples, the copolycarbonate comprises 50 to 90 wt%, preferably 60 to 95 wt%, 1 to 10 wt%, preferably 4 to 10 wt%, of the segment represented by formula I, 1 to 40 wt%, preferably 1 to 30 wt%, of the segment represented by formula III.
In some examples, the copolycarbonate has a weight average molecular weight of 18000 to 50000g/mol, preferably 22000 to 35000 g/mol.
The invention also provides a preparation method of the polysiloxane end-capped modified copolycarbonate, as described above, wherein the overall reaction flow is shown in fig. 1, and the method specifically comprises the following steps:
1) continuously adding reaction raw materials of phosgene, BPA phenol sodium salt water solution, PDMS monomer solution and inert organic solvent into a polymerization reactor R-1 for photochemical reaction;
2) continuously conveying the oligomer emulsion in the polymerization reactor R-1 to a polymerization reactor R-2, and simultaneously adding a single-end reaction active PDMS monomer solution for copolymerization reaction;
3) continuously conveying the copolymerization reaction liquid to a polymerization reactor R-3, and continuously adding a capping agent solution and a catalyst solution to perform polycondensation;
4) continuously conveying the polycondensation reaction liquid to a polymerization reactor R-4 until the polycondensation reaction is completed, and continuously conveying the polymer solution to a storage tank D-1;
5) and purifying the polymer solution, removing the organic solvent, and collecting to obtain the copolycarbonate.
In some preferred examples, the polymerization reactor in step 1 may also be carried out in a multi-tank series manner, for example, without limitation, by using two or three continuous tank reactors for photochemical reaction, in order to increase the conversion rate of the polymerization reaction.
In some examples, the pH of the reaction solution is controlled between 11 and 12, preferably between 11.5 and 11.7 during the reaction of each step by adding an aqueous alkali metal hydroxide solution;
preferably, the alkali metal hydroxide is selected from one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide, cesium hydroxide, preferably sodium hydroxide.
Preferably, the concentration of the alkali metal hydroxide solution is 25 to 40%, preferably 30 to 35%.
In some examples, the reaction residence time in each polymerization reactor in each step is independently 10 to 30min, preferably 10 to 15 min;
preferably, the reaction temperature in each polymerization reactor in each step is independently 30 to 35 ℃.
In some examples, in step 1), the molar ratio of phosgene to BPA phenol sodium salt is (1.01-1.3): 1, preferably (1.1-1.15): 1; the amount of the PDMS monomer is 0.01-0.8 time of the mass of BPA with the molar quantity equal to that of BPA phenolic sodium salt in the step 1).
In some examples, in step 2), the amount of the single-end reaction-active PDMS monomer is 0.01 to 0.2 times the mass of BPA in an equimolar amount to the amount of BPA phenolic sodium salt in step 1).
In some examples, in step 3), the amount of the end-capping agent is (20-40): 1, preferably (27-30): 1; the dosage of the catalyst is (160-10000): 1, preferably (200-1000): 1 based on the molar ratio of the BPA phenol sodium salt to the catalyst;
preferably, the end-capping agent is one or more of phenol, p-cumylphenol, p-methylphenol, p-isopropylphenol, p-tert-butylphenol and p-cyanophenol, preferably one or two of p-tert-butylphenol and p-cyanophenol; the catalyst is one or more of triethylamine, tetrabutylammonium bromide and tetrabutylammonium chloride, and triethylamine is preferred.
In some examples, the structural formula of the mono-terminal reactive PDMS monomer is shown in formula iv:
in the formula IV, m is an integer of 10-100, preferably an integer of 20-50; r1 is C1-C6 alkyl, preferably C2-C4 alkyl; r2 is an alkyleneoxy group having from C1 to C6, preferably from C2 to C4; r3 is selected from hydroxy or carboxy;
the above-mentioned single-terminal reactive PDMS monomer may be commercially available, or may be prepared by referring to published literature data, for example, the preparation process of single-terminal polysiloxane described in patent publications CN102532551A and CN 101508778B.
Preferably, the PDMS monomer is a bis-eugenol-terminated polydimethylsiloxane, and the structural expression thereof is shown in formula v:
in the formula V, n is an integer of 20-150, preferably 40-90.
The bis-eugenol end-capped polydimethylsiloxane can be purchased from commercial products, and can also be prepared by referring to published literature data, such as end-phenolic polysiloxane and a preparation method thereof described in patent publication CN110776640A, and homemade bis-hydrogen end-capped polysiloxane described in academic paper [ Litao, eugenol modified silicone oil modified polycarbonate, southwest transportation university, 2014], and the like.
In some preferred examples, bisphenol a (also known as BPA) is dissolved in an aqueous solution of an alkali metal hydroxide to obtain an aqueous solution of BPA sodium phenolate; in the BPA phenol sodium salt aqueous solution, the concentration of BPA is 150-200 g/L, preferably 160-170 g/L.
In some preferred examples, the concentration of the mono-terminal reactive PDMS monomer solution is 10 to 20%, preferably 15%.
In some preferred examples, the concentration of the PDMS monomer solution is 10 to 20%, preferably 15%.
In some preferred examples, the concentration of the end-capping reagent solution is 10 to 20%, preferably 10 to 15%; the concentration of the catalyst solution is 1-10%, preferably 2-5%.
In some preferred examples, the inert organic solvent is selected from one or more of dichloromethane, trichloromethane, dichloroethane, trichloroethane, preferably dichloromethane. The total dosage of the inert organic solvent in the reaction system is that the solid content of the product in the reaction liquid is 10-20%, and preferably 15-18%.
In some preferred examples, the post-treatment operations such as purification and removal of organic solvent in step 5) may be performed by methods conventional in the art, such as: the copolymer emulsion is first oil-water separated, and the oil phase is washed with alkali, acid and water successively, and the solvent is eliminated from the washed oil phase, crushed and dried to obtain qualified powder.
The invention has the beneficial effects that:
according to the method, the prepared copolycarbonate of which the end group contains the polyorganosiloxane chain segment improves the flame retardant property, the chemical resistance and the low-temperature impact resistance of the material, and widens the application field of the copolycarbonate material; in addition, the molecular weight and the composition of the prepared copolymer can be regulated, and the preparation method is simple and easy to operate, has mild conditions, is convenient for industrial realization, and has good industrial application prospect.
Drawings
FIG. 1 is an overall reaction scheme of a method for preparing copolycarbonates according to the present invention.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative of the invention and are not to be construed as limiting the scope of the invention.
The analytical evaluation methods referred to in examples or comparative examples are as follows:
(1) the molecular weight is measured by Gel Permeation Chromatography (GPC), and is measured by a gel permeation chromatograph with model number Waters 1515, wherein the solvent is tetrahydrofuran, PS is standard sample, the temperature is 30 deg.C, and the time is 45 min;
(2) -40 ℃ notched Izod impact Strength measured according to the standard test method for Izod impact testing of plastics specified in ASTM D256-1997;
(3) test for flame retardancy
Flammability was evaluated according to the Underwriter's Laboratory Bulletin 94 protocol entitled "Tests for flexibility of Plastic Materials for Parts in Devices and applications" (ISBN 0-7629-. Several ratings may be available based on the rate of burning, the extinguishing time, the ability to resist dripping, and whether the drips are burning. Following this protocol, materials can be classified as UL94 HB, V0, V1, V2, 5VA, and 5 VB;
(4) test for solvent resistance
After a sunscreen (Banan Board) was applied to a test piece (test piece thickness 3.2mm) for tensile strength test in a 1.0% strain jig according to ASTM D543, the change in appearance was observed and classified into four grades, A (no crack), B (crack), C (severe crack) and D (break) according to the weight of the crack.
The comonomer sources used in the examples are as follows:
(1) the molecular structure expression of the single-end reactive PDMS monomer is shown below, and the source is shown in table 1 for different m values of the product:
TABLE 1 Single-terminal reactive PDMS monomer information
Numbering
Terminal group
m
Source
Number plate
PDMS-mono-19
Hydroxy radical
19
Xinyue chemistry (X-22 series)
X-2220
PDMS-Mono-51
Hydroxy radical
51
Xinyue chemistry (X-22 series)
X-2250
PDMS-mono-38
Carboxyl group
38
Xinyue chemistry (X-22 series)
X-2240
(2) < preparation of eugenol-terminated polydimethylsiloxane monomer >
Octamethylcyclotetrasiloxane (1420g, 4.80mol), tetramethyldisiloxane (40.2g, 0.3mol) and clay catalyst Filtrol 20(23.4g, 1.6 wt%) were added to a reaction vessel equipped with a stirrer and a thermometer and stirred for 40 minutes to homogenize the material mixture, then the reaction system was heated up to 50 ℃ at a rate of 5 ℃/min and stirred at that temperature for 3 hours, and then the temperature of the reaction system was continuously heated up to 120 ℃ at a rate of 5 ℃/min and stirred vigorously at that temperature for 5 hours, after which the clay catalyst was removed by filtration. Then, the material after removal of the clay catalyst was put into a reaction tank equipped with a stirrer and a thermometer and a mixed solution of eugenol (167.2g, 1.02mol) and platinum catalyst (karstedt) (0.67g) was added dropwise at a rate of 20 g/min with stirring, after which the reaction was stirred at a temperature of 80 ℃ for 13 hours. Then distilling at 200 ℃ under reduced pressure to 0.2kPa to remove unreacted raw materials to obtain the eugenol end-capped polydimethylsiloxane, wherein the yield is 99%, the polymerization degree of PDMS is detected to be 48 through nuclear magnetism, and the PDMS is defined as PDMS-bis-48 in the invention for convenience;
otherwise, by varying the amount of tetramethyldisiloxane by 20g, a monomer having a degree of polymerization of siloxane of 89 was prepared, and for convenience, is defined herein as PDMS-bis-89.
[ examples 1 to 17 ] and comparative examples 1 to 5 ]
Copolycarbonates in the corresponding examples and comparative examples were prepared according to the following methods, respectively:
(1) preparing raw material solutions:
according to the raw material quality in Table 2, BPA phenolate solution with BPA concentration of 170g/L and 32% sodium hydroxide solution are respectively prepared by using water as a solvent. Using dichloromethane as solvent, preparing 15% eugenol end-capped polydimethylsiloxane solution, 15% single-end reaction active PDMS monomer solution, 5% triethylamine solution, 11% p-tert-butylphenol or p-cyanophenol solution. And preparing a plurality of dichloromethane as an inert reaction solvent, and controlling the addition amount of the dichloromethane in the system to make the solid content of the product in the final reaction liquid be 16%.
(2) According to the feeding amount in the table 2, phosgene, a BPA phenol sodium salt solution, a eugenol-terminated polydimethylsiloxane solution, dichloromethane and a sodium hydroxide solution are continuously added into a polymerization reactor R-1, the pH of a reaction solution is maintained to be 11.5, the reaction temperature is maintained to be 30 ℃, and photochemical reaction is carried out in the reactor R-1; after reacting for 10min, continuously conveying the oligomer emulsion in the R-1 into a polymerization reactor R-2, and simultaneously adding a single-end reaction active PDMS monomer solution for copolymerization reaction; after the reaction stays for 10min, continuously conveying the reaction liquid to a polymerization reactor R-3, continuously adding a blocking agent solution and a triethylamine solution into a pipeline at the same time, and carrying out polycondensation reaction in the R-3; after reacting for 10min, the polymer solution is conveyed to a polymerization reactor R-4, and after staying in the reactor R-4 for 10min, the polymer solution is continuously conveyed to a storage tank D-1.
(3) And (3) post-treatment: and (3) purifying the polymer solution prepared in the step (2), removing the organic solvent, and collecting to obtain the product polycarbonate.
The properties in Table 3 were tested for each of the examples and for the comparative polycarbonate, and the results are shown in Table 3.
As can be seen from the comparison of the data in Table 3, the introduction of a polysiloxane molecular chain at the end of the molecular chain of siloxane copolycarbonate can improve the intrinsic flame retardant property and chemical resistance of polycarbonate, effectively improve the properties of polycarbonate, and broaden the application fields of materials.
In addition, comparative example 1 does not have silicone modification as compared with examples 2 to 5 and 10 to 14, and does not have any advantage in low-temperature impact resistance, flame retardancy, and solvent resistance. Comparative example 2 is a cyanophenol-terminated structure as in example 17, but it is not silicone-modified relative to example 17, and is also inferior in all aspects, and has only slightly improved flame retardant performance compared with comparative example 1. Comparative example 3 maintained the same siloxane content (20%) relative to examples 5-9, 16, but without the addition of the mono-terminal reactive PDMS monomer, silicone protection was not formed on the surface of the copolymeric material, and both flame retardancy and solvent resistance were poor. Comparative example 4 maintained the same siloxane content (6%) relative to examples 1-3, 17, but no bis-eugenol-terminated PDMS monomer was added, resulting in a significant reduction in low temperature impact resistance.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be regarded as the protection scope of the present invention.
Table 2, examples and comparative examples
BPA/g
Phosgene/g
PDMS-mono-19/g
PDMS-mono-38/g
PDMS-mono-51/g
PDMS-bis-48/g
PDMS-bis-89/g
Para-tert-butylPhenylphenol per gram
Para-cyanophenol/g
Triethylamine/g
Example 1
4560
2277
55
273
136
8
Example 2
4560
2277
218
109
111
8
Example 3
4560
2277
164
163
111
8
Example 4
4560
2277
285
284
111
8
Example 5
4560
2277
320
960
111
8
Example 6
4560
2277
320
960
103
8
Example 7
4560
2277
320
961
100
8
Example 8
4560
2277
512
769
136
8
Example 9
4560
2277
384
897
115
8
Example 10
4560
2277
366
1829
111
8
Example 11
4560
2277
732
1464
111
8
Example 12
4560
2277
512
2903
111
8
Example 13
4560
2277
512
2903
111
8
Example 14
4560
2277
85
3330
111
8
Example 15
4560
2277
85
3330
88
8
Example 16
4560
2277
384
897
92
8
Example 17
4560
2277
55
273
108
8
Comparative example 1
4560
2277
111
8
Comparative example 2
4560
2277
108
8
Comparative example 3
4560
2277
1280
111
8
Comparative example 4
4560
2277
328
136
8
TABLE 3 results of polycarbonate Performance test