CN114957672A

CN114957672A - Polycarbonate-polyorganosiloxane copolymer, method for producing same, and polycarbonate resin composition containing same

Info

Publication number: CN114957672A
Application number: CN202210769637.1A
Authority: CN
Inventors: 魏志涛; 曾伟; 王磊; 黎雷; 张珏; 李凤闯; 李晓飞; 李强; 姜进科; 初乃波; 黎源
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2022-06-30
Filing date: 2022-06-30
Publication date: 2022-08-30

Abstract

The present invention discloses a polycarbonate-polyorganosiloxane copolymer, a method for producing the same, and a polycarbonate resin composition containing the same, wherein the polycarbonate-polyorganosiloxane copolymer comprises a polysiloxane segment and a polycarbonate segment, and has a weight average molecular weight of 20000-50000 as measured by gel chromatography, a molecular weight distribution of 2.5 or less, and in a molecular weight distribution curve obtained by measurement with log (M) as the horizontal axis and dw/dlog (M) as the vertical axis, the sum of the integrated area of the portion log (M) of 5 or more and the integrated area of the portion log (M) of 3.7 or less is 10% or less relative to the integrated area of the entire curve. The polycarbonate-polyorganosiloxane copolymer of the present invention has excellent heat resistance and yellowing resistance. In addition, the polycarbonate resin composition comprising the polycarbonate-polyorganosiloxane copolymer of the present invention has excellent low-temperature impact resistance and heat resistance.

Description

Polycarbonate-polyorganosiloxane copolymer, method for producing same, and polycarbonate resin composition containing same

Technical Field

The invention relates to a copolymer, in particular to a polycarbonate-polyorganosiloxane copolymer, a preparation method and a polycarbonate resin composition containing the copolymer, belonging to the technical field of high polymer materials.

Background

Polycarbonate (PC) is a high molecular polymer containing carbonate bonds in molecular chains, and can be divided into aliphatic, alicyclic, aliphatic-aromatic and aromatic polycarbonates, wherein the aromatic polycarbonate has excellent mechanical properties, heat resistance, impact toughness, electrical insulation and light transmission, low creep resistance and water absorption, good dimensional stability, excellent dielectric properties and the like, can be used as a thermoplastic engineering plastic, and can be widely applied to the fields of automobiles, electronic equipment, buildings, office supplies, optical discs, sports equipment, medical care, computers, aerospace and the like. However, the common aromatic polycarbonate material also has certain defects, such as poor solvent resistance, easy stress cracking after being touched by a solvent, poor impact performance at low temperature, limitation of the application of the material in low-temperature places and the like, and modification is needed in order to widen the application field of the material.

It is known that the low-temperature impact resistance, chemical resistance and the like of polycarbonate materials can be improved by modifying the polycarbonate materials, such as by adding silicon-based modification and improving the low-temperature impact strength of polycarbonate by blending; the low-temperature resistance of the material can be improved by means of copolymerization of polycarbonate and polysiloxane, and compared with the blending modification means, the method has more reliable and more excellent performance, is remarkable in the aspects of flame retardance, low-temperature impact resistance, chemical corrosion resistance, aging resistance and the like, and is widely used for producing products such as consumer electronic cover plates, sheaths, supports, helmets, new energy automobile charging piles, charging guns and the like.

Chinese patent CN106928439A discloses a low temperature resistant non-transparent high impact resistant random copolymerized carbonate and a preparation method thereof, wherein the weight percentage of polysiloxane block in the random copolymerized carbonate is 15-20%, the preparation method is a one-step method, alkali liquor and catalyst are uniformly added into a reaction system step by step, which can cause the problem of local implosion, and the content ratio of low polymer and high polymer in the copolymer is high; patent CN201380052733.3 proposes a method for producing a siloxane copolycarbonate, in which an aqueous solution of a basic compound of a dihydric phenol compound fed from a dissolution tank of the dihydric phenol compound is mixed with an aqueous solution of a basic compound to increase the concentration of the basic compound to the dihydric phenol compound before the aqueous solution is brought into contact with a polycarbonate oligomer and PDMS in a process for producing a PC-POS from the polycarbonate oligomer, thereby reducing the amount of unreacted PDMS and producing a high-quality polycarbonate-polyorganosiloxane copolymer excellent in transparency, impact resistance and the like economically and stably, and a catalyst is directly added to the system.

Chinese patent CN 201480011521.5 proposes a polycarbonate-polyorganosiloxane copolymer having transparency and excellent impact resistance, particularly impact resistance at low temperatures, which achieves the effects of the invention by controlling the molecular weight distribution of polyorganosiloxane monomers in the polycarbonate-polyorganosiloxane copolymer, the preparation method is a general method for preparing siloxane polycarbonate, and when alkali solution and a catalyst are directly added to a reaction system, there is also a problem of local polymerization unevenness, and there is no mention of the problem of the ratio of low molecular weight to ultra high molecular weight in the polycarbonate-polyorganosiloxane copolymer.

Chinese patent CN201480055008.6 proposes a polycarbonate-organosiloxane copolymer having optical properties, said polydiorganosiloxane-polycarbonate block copolymer producing molded articles having a haze of less than 1.5% at a thickness of 3.15mm, the method employing a combination of hydroxyaryl-terminated polydiorganosiloxane monomers as comonomers and defining a molecular weight distribution of the siloxane monomer composition, wherein the polysiloxane monomer composition has a polydispersity index (Mw/Mn) of less than 2.3 as measured by size exclusion chromatography with Ultraviolet (UV) and Refractive Index (RI) measurements; and the low molecular weight component% of the polysiloxane monomer composition is less than 15%, i.e., the patent also achieves the object of the invention by defining the molecular weight distribution of the siloxane comonomer, does not address the ratio of low polymer to high polymer in the polycarbonate-polysiloxane copolymer, and the preparation method is also conventional.

Chinese patent CN201480077736.7 provides a polyorganosiloxane having a differential molecular weight distribution curve of dw/dlog (M) obtained by gel permeation chromatography based on polystyrene as a conversion standard, the abscissa axis of which is log (M) of the molecular weight M, and the ordinate axis of which is dw/dlog (M) obtained by differentiating the concentration percentage w by log (M) of the molecular weight, in which the value obtained by integrating the dw/dlog (M) value in the range of 2.5 or less log (M) or less 3.1 is 0 to 10% relative to the value obtained by integrating the dw/dlog (M) value in the entire range of log (M), i.e., the patent also defines the molecular weight distribution curve of a siloxane monomer, and does not mention the molecular weight distribution integral curve of a polycarbonate-polysiloxane copolymer and the heat and yellowing resistance of a product; chinese patent CN201680018579.1 and Chinese patent CN 201680034894.3 propose a resin composition comprising a polycarbonate-polysiloxane copolymer, wherein the polyorganosiloxane is obtained by blending a plurality of polyorganosiloxanes having a molecular weight differential distribution curve of dw/dlog (M) obtained by a gel permeation chromatography method using polystyrene as a conversion standard, the abscissa axis of which is a logarithmic value of the molecular weight M (M), and the ordinate axis of which is a logarithmic value of the molecular weight log (M) of the concentration ratio w (1) in which the value of dw/dlog (M) is the largest in the range of 3.4. ltoreq. log (M) 4.0, (2) in the molecular weight differential distribution curve, the integral value of dw/dlog (M) in the range of 4.00. ltoreq. log (M) 4.50 is 6 to 40% of the integral value of dw/dlog (M) over the entire range of log (M), that is, the polycarbonate-polysiloxane copolymer used in the composition only defines the molecular weight distribution of the polysiloxane monomer added before polymerization, the molecular weight distribution curve of the copolymer after polymerization is not defined, and the proportion problem of small molecular oligomers and ultrahigh molecular weight polymers in the copolymer, and the heat resistance and yellowing resistance of the copolymer and the composition are not mentioned. The molecular weight distribution of the siloxane monomer is greatly different from that of the final polycarbonate-polysiloxane copolymer, and the relationship between the structure and the performance of the polymer and the polymerization process parameters is large.

In summary, it is desirable from a polymerization process point of view to prepare a polysiloxane-polycarbonate copolymer having a low oligomer content and a low polymer content, which balances the processability and the heat-resistant stability of the material.

Disclosure of Invention

The inventor comprehensively researches the structure and the performance of the polycarbonate-polyorganosiloxane copolymer, and finds that the molecular structure with ultrahigh molecular weight and the structure with ultralow molecular weight in the copolymer have great influence on the performance of the copolymer material, the content of the part with ultralow molecular weight is high, the long-term heat resistance and the aging resistance of the material can be greatly reduced, the processing fluidity of the polymer with ultrahigh molecular weight is poor, the higher the content is, the problems of poor flowing and uneven mixing during the processing and modification of the polymer can be caused, and the problem of unstable performance of the prepared product can be further caused.

The present inventors have found, through studies, that in the production of a polycarbonate-polyorganosiloxane copolymer, the addition mode of the alkali metal hydroxide and the catalyst has great influence on the polymerization reaction rate, especially the problem of implosion at the contact interface can be generated at the moment of contact of the alkali metal hydroxide and the catalyst with the oligomer reaction liquid, a copolymer with high molecular weight can be generated instantaneously, the part which is contacted with the alkali liquor and the catalyst at the latest has the slowest reaction rate, the obtained molecular weight is very low, that is, the way of adding the alkali metal hydroxide and the catalyst inevitably causes the problem of uneven reaction on the contact surface, the present invention avoids the problem of uneven local reaction by changing the way of adding the alkali metal hydroxide and the catalyst, and the contents of the prepared copolymer oligomer and polymer are both significantly reduced, thereby achieving the above objects, and completing the present invention.

An object of the present invention is to provide a polycarbonate-polyorganosiloxane copolymer having a small proportion of ultra-high molecular weight molecular structures and ultra-low molecular weight molecular structures and a narrow molecular weight distribution, thereby having excellent heat-and yellowing-resistance.

It is still another object of the present invention to provide a method for preparing such a polycarbonate-polyorganosiloxane copolymer.

It is still another object of the present invention to provide a polycarbonate resin composition containing such a polycarbonate-polyorganosiloxane copolymer, which has excellent low-temperature impact resistance and heat resistance.

In order to achieve the purpose, the invention adopts the following technical scheme:

a polycarbonate-polyorganosiloxane copolymer comprising polysiloxane segments and polycarbonate segments and having the following structural features:

a. the polycarbonate-polyorganosiloxane copolymer has a weight-average molecular weight of 20000-50000 and a molecular weight distribution of 2.5 or less as determined by gel chromatography, and in a molecular weight distribution curve having the log (M) as the horizontal axis and dw/dlog (M) as the vertical axis, the sum of the integrated area of the log (M) or more than 5 and the integrated area of the log (M) or less than 3.7 is 10% or less of the integrated area of the entire curve,

b. the polycarbonate chain segment comprises a structural unit shown in a formula I; the polysiloxane chain segment comprises a structural unit shown as a formula II;

wherein R is ₁ And R ₂ Each independently represents hydrogen, halogen, C1-20 alkyl, C4-20 cycloalkyl or C6-20 aryl; a and b independently represent an integer of 0 to 4; x is present or absent, when X is absent, i.e. two benzenesThe biphenyl diphenol structure with directly connected rings represents ether group, carbonyl group, thioether group, sulfone group, sulfoxide group, alkylene group with 1-20 carbon atoms, arylene group with 6-20 carbon atoms, alicyclic group with 6-20 carbon atoms or

A group represented by (the attachment site is a C atom in the formula); wherein R 'and R' independently represent an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 4 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; or, R 'and R' together form a carbon number 4-20 alicyclic ring, which carbon number 4-20 alicyclic ring may be optionally substituted with one or more carbon number 1-20 alkyl groups, carbon number 6-20 aryl groups, carbon number 7-21 aralkyl groups, carbon number 5-20 cycloalkyl groups, or combinations thereof;

R ₃ and R ₄ Each independently represents hydrogen, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms; y represents a single bond, an organic residue optionally comprising aliphatic or aromatic groups;

n ₁ selected from 80 to 150, preferably from 90 to 120; n is ₂ Selected from 40-79, preferably 40-60; n is ₃ Is selected from 10-39, preferably 20-30.

In a particular embodiment, the total content by mass of polyorganosiloxane segments in the copolymer is from 5 to 40%.

In a specific embodiment, the polycarbonate segment is a structural unit derived from bisphenol a and comprises a unit structure represented by formula iii:

in a specific embodiment, the polyorganosiloxane segment is a structural unit derived from a phenolic hydroxyl terminated polydimethylsiloxane, as shown in formula IV; the phenolic hydroxyl group is derived from a phenol having an ethylenically unsaturated carbon-carbon bond, preferably allyl phenol, eugenol, vinyl phenol or isopropenyl phenol, more preferably allyl phenol or eugenol. Examples of the allylphenol include 2-allylphenol, 3-allylphenol, 4-allylphenol, 2-methoxy-5-allylphenol, and 2-methoxy-6-allylphenol, preferably 2-allylphenol, and 2-methoxy-4-allylphenol.

In the formula IV, R is connected on a benzene ring ₅ The structure (2) represents the residue of the above phenol after removal of the hydroxyl group, R ₅ Represents a substituted or unsubstituted alkylene group, a substituted or unsubstituted cycloalkylene group, or a substituted or unsubstituted arylene group; preferably, R ₅ The selection type and the position of the phenol correspond to the substituent groups on the phenol benzene ring one by one. Wherein p is 0 to 5, preferably 0 to 3.

In another aspect, a method for preparing the polycarbonate-polyorganosiloxane copolymer comprises the steps of:

1) a, a step A: adding a salt solution of alkali metal hydroxide of a diphenol compound, phosgene, an inert organic solvent, terminal phenol silicone oil and the like into a polymerization reactor for reaction to obtain an oligomer mixed solution, and separating oil phase and water phase of the oligomer mixed solution to obtain an oil phase and a water phase.

The sodium phenolate solution of the bisphenol compound is prepared by dissolving the bisphenol compound in an aqueous solution of alkali metal hydroxide, and the concentration of the sodium phenolate solution is preferably 150-200g/L, more preferably 160-170g/L in terms of the mass concentration of the bisphenol compound; the bisphenol compound is preferably one or more of 2, 2-bis (4-hydroxyphenyl) propane (i.e., bisphenol a), bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane, 2-bis (4-hydroxy-3, 5-dimethylphenyl) propane, 4' -dihydroxybiphenyl, 2-bis (4-hydroxyphenyl) butane, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) diphenylmethane, 2-bis (4-hydroxy-3-methylphenyl) propane, and bis (4-hydroxyphenyl) naphthylmethane.

The phenolic hydroxyl terminated polysiloxane monomer is obtained by carrying out double-end-capping reaction on phenols with olefinic unsaturated carbon-carbon bonds and polydimethylsiloxane; the phenols are preferably one or more of allyl phenol, eugenol, vinyl phenol and isopropenyl phenol.

The end capping agent is one or more of phenol, p-cumylphenol, p-methylphenol, p-isopropylphenol, p-tert-butylphenol and p-cyanophenol, and is preferably p-tert-butylphenol or p-cumylphenol; the concentration of the blocking agent solution is preferably 10 to 20%, more preferably 10 to 15%.

The inert organic solvent is one or more of dichloromethane, trichloromethane, dichloroethane and trichloroethane, preferably dichloromethane.

The amount of the phosgene used is 1.01 to 1.3, preferably 1.1 to 1.15, in terms of a molar ratio of the bisphenol compound to the phosgene.

The molar ratio of the bisphenol compound to the end-capping agent is 20 to 40, preferably 27 to 30.

The inert organic solvent is added in an amount such that the reaction solution has a solid content of 10 to 30%, preferably 12 to 20%.

Further, the weight average molecular weight of the oligomer obtained by polymerization in the step A is 1000-4000g/mol, preferably 1500-3000 g/mol.

2) And a step B: adding a catalyst solution and a blocking agent solution into the oil phase obtained in the step A, and uniformly mixing; an aqueous solution of an alkali metal hydroxide is added to the aqueous phase obtained in step A.

The catalyst is one or more of triethylamine, tetrabutylammonium bromide and tetrabutylammonium chloride, and triethylamine is preferred; the concentration of the catalyst solution is preferably 1 to 10%, more preferably 2 to 5%; the amount of the catalyst is 1 to 10 per thousand, preferably 3 to 6 per thousand of the molar amount of the bisphenol compound.

The alkali metal hydroxide is one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide and cesium hydroxide, and sodium hydroxide is preferred; the concentration of the alkali metal hydroxide solution is preferably 25 to 40%, more preferably 30 to 35%.

Further, the amount of the alkali metal hydroxide added to the aqueous phase in the step B is such that the pH of the aqueous phase after completion of the polymerization in the step C is maintained at 11 to 12.9, preferably 11.5 to 12.5.

3) And a step C: and (c) mixing the oil phase and the water phase obtained in the step (B), and completing the polymerization reaction under stirring to obtain the siloxane copolycarbonate solution.

4) Step D: and D, washing and purifying the copolymer solution prepared in the working procedure C, and removing the organic solvent to obtain a target product.

The post-treatment may be carried out 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.

In still another aspect, a polycarbonate resin composition comprises the polycarbonate-polyorganosiloxane copolymer or the polycarbonate-polyorganosiloxane copolymer prepared by the method and optionally an aromatic polycarbonate, wherein the polycarbonate-polyorganosiloxane copolymer accounts for 1 to 100% by mass, and the aromatic polycarbonate accounts for 0 to 99% by mass.

Preferably, the other aromatic polycarbonate is a siloxane-free polycarbonate such as a bisphenol A type homopolycarbonate prepared by a known phosgene interface method or a bisphenol A type homopolycarbonate prepared by a melt transesterification method.

Preferably, the resin composition also comprises an optional addition auxiliary agent, and the content of the addition auxiliary agent is 0-5% of the total mass of the polysiloxane-polycarbonate copolymer and other aromatic polycarbonate. The additive auxiliary agent is selected from one or more of a mold release agent, a flow auxiliary agent, a heat stabilizer, an antioxidant, a UV absorbent, an IR absorbent, a flame retardant, an antistatic agent, a dye, a pigment and a filler.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, the problem of uneven local reaction is avoided by changing the adding mode of the catalyst and the alkali metal hydroxide solution in the polycondensation stage, and the siloxane copolycarbonate with ultra-high molecular weight and ultra-low molecular weight content is prepared, wherein the copolymer has the advantages of excellent heat resistance and excellent processing performance, and in addition, the polycarbonate resin composition containing the polycarbonate-polyorganosiloxane copolymer has excellent chemical resistance and low-temperature impact resistance.

Detailed Description

The following examples will further illustrate the method provided by the present invention in order to better understand the technical solution of the present invention, but the present invention is not limited to the listed examples, and should also include any other known modifications within the scope of the claims of the present invention.

The analytical evaluation methods referred to in examples or comparative examples are as follows:

(1) the molecular weight of the polymer was measured by Gel Permeation Chromatography (GPC), Agilent Technologies1260 definition, dichloromethane as the mobile phase, PS as the standard, flow rate of 1mL/min, column temperature and tank temperature of 30 ℃.

The differential molecular weight distribution curve can be obtained as follows. First, a time curve (elution curve) of the intensity distribution detected in the RI detection meter was prepared as a molecular weight distribution curve with respect to a logarithmic value (log (M)) of the molecular weight using a standard curve. Then, an integral molecular weight distribution curve with respect to log (m) is obtained when the total area of the distribution curve is set to 100%, and the integral molecular weight distribution curve is differentiated by log (m), whereby a differential molecular weight distribution curve with respect to log (m) can be obtained. A series of operations until a differential molecular weight distribution curve is obtained can be generally performed by using analysis software incorporated in a GPC measurement apparatus.

(2) Izod impact properties were measured according to the standard test method for Izod impact testing of plastics as specified in ASTM D256-1997.

(3) Siloxane content test

By nuclear magnetic analysis of copolymers ¹ The H-NMR spectrum was calculated by comparing the integral ratio of the peak derived from the bisphenol compound (I) with the integral ratio of the peak derived from the phenolic hydroxyl group-terminated polysiloxane (II).

(4) Yellowness Index (YI) was measured according to ASTM E313 standard, test piece size 50 x 10mm, heat resistance YI value was measured after placing polycarbonate powder in an oven at 200 ℃ for 48 h.

(5) The heat resistance test requires that the dried granules are kept for 10min at 300 ℃ of an injection molding machine, and the weight average molecular weight of a heat-resistant test piece is measured and is different from the initial value, namely the heat-resistant molecular weight.

Preparation of eugenol-terminated polysiloxane monomers

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 removing the clay catalyst was put into a reaction kettle equipped with a stirrer and a thermometer and a mixed solution of eugenol (167.2g, 1.02mol) and karstedt's platinum catalyst (0.67g) was added dropwise at a rate of 20 g/min with stirring, followed by stirring reaction at a temperature of 80 ℃ for 13 hours. Followed by distillation at 200 ℃ under reduced pressure to 0.2kPa to remove unreacted starting materials, to give eugenol-terminated polysiloxane in a yield of 99%, with a degree of polymerization of PDMS 55 as determined by nuclear magnetic detection, herein defined for convenience as PDMS-55;

other conditions were unchanged, and by varying the amount of tetramethyldisiloxane, a monomer having a degree of siloxane polymerization of 89 (corresponding to an amount of tetramethyldisiloxane of 20.1g), defined herein as PDMS-89, and a monomer having a degree of siloxane polymerization of 21 (corresponding to an amount of tetramethyldisiloxane of 80.4g), defined herein as PDMS-21, were prepared, respectively.

[ example 1 ]

(1) Preparation of PC-PDMS oligomer:

3409g of BPA, 14386g of ultrapure water, 3903g of 32% sodium hydroxide aqueous solution and 2.3g of sodium hydrosulfite are added into a 50L tank-shaped reactor with a baffle plate, a paddle-type stirring blade and a cooling jacket, stirring is carried out under the nitrogen atmosphere to dissolve the ultrapure water, 27131g of dichloromethane and 958g of PDMS-55 are added, 1702g of phosgene is introduced into the reactor within 10min while cooling water is introduced into the jacket, the temperature of the reaction liquid is kept below 35 ℃, and after the phosgene introduction, stirring is carried out for 10min to obtain BPA-PDMS oligomer mixed reaction liquid;

the reaction solution overflowing from the tank-type reactor was continuously taken out, allowed to stand, and the aqueous phase was separated and removed to obtain a methylene chloride phase.

(2) Oil-water separation and addition of alkali liquor and catalyst

Stopping stirring in the step (1), refining for 10min, separating the reaction liquid into two phases, separating the two phases, adding 1050g of 32% sodium hydroxide aqueous solution into the water phase, uniformly stirring, adding 201g of 3 wt% triethylamine/dichloromethane solution and 775g of 10% p-tert-butylphenol/dichloromethane solution into the oil phase, and uniformly mixing;

(3) carrying out a polycondensation reaction

And (3) starting stirring in a 50L tank type reactor provided with baffles, paddle type stirring wings and a cooling jacket, adding the water phase and the oil phase obtained in the step (2) into the reactor, controlling the reaction temperature to be below 40 ℃, and stirring until the reaction system is free of acyl chloride.

(4) And (3) post-treatment: washing the dichloromethane solution of PC-PDMS prepared in step (3) with NaOH aqueous solution of 0.03mol/L and 0.2N hydrochloric acid at 15 vol% relative to the solution in sequence, and then repeatedly washing with pure water until the electric conductivity of the washed aqueous phase is below 100 muS/cm; the polycarbonate obtained by washing in methylene chloride solution was concentrated and pulverized, and the obtained powder was dried under reduced pressure at 140 ℃ for 4 hours.

[ examples 2 to 9 ]

The preparation method of each example is completely consistent with the steps, except that the addition amount of part of the raw materials is changed, and the changed raw materials are shown in the following table 1:

TABLE 1 feed amount of raw material monomer in each example

Examples	PTBP solution/g	Methylene chloride/g	PDMS-55/g	PDMS-21/g	PDMS-89/g
						1	775	27132	958	/	/
2	936	27132	958	/	/
						3	591	27132	958	/	/
4	775	22848	202	/	/
						5	775	24117	426	/	/
6	775	31007	1642	/	/
						7	775	36175	2554	/	/
8	775	27132	/	957	/
						9	775	27132	/	/	957

Comparative example 1:

3409g of BPA, 14386g of ultrapure water, 3903g of 32% aqueous sodium hydroxide solution and 2.3g of sodium dithionite are added into a 50L tank-shaped reactor provided with a baffle plate, a paddle-type stirring blade and a cooling jacket, stirred under a nitrogen atmosphere to be dissolved into a clear and transparent sodium phenolate aqueous solution, 27131g of dichloromethane and 958g of PDMS-55 are added, 1702g of phosgene are introduced into the reactor within 10min while stirring, cooling water is introduced into the jacket to keep the temperature of the reaction solution below 35 ℃, after the introduction of the phosgene, the reaction solution is stirred for 10min to obtain a BPA-PDMS oligomer mixed reaction solution, 1050g of 32% aqueous sodium hydroxide solution, 201g of triethylamine/dichloromethane solution with a concentration of 3 wt% and 775g of p-tert-butylphenol/dichloromethane solution with a concentration of 10% are added into the reaction system while stirring, stopping stirring when no acyl chloride exists in the reaction system, standing for layering, taking out an oil phase, sequentially cleaning with a 0.03mol/L NaOH aqueous solution and 0.2N hydrochloric acid which account for 15 vol% of the oil phase solution, and then repeatedly cleaning with pure water until the conductivity of the cleaned water phase is below 100 muS/cm; the polycarbonate obtained by washing in methylene chloride solution was concentrated and pulverized, and the obtained powder was dried under reduced pressure at 140 ℃ for 4 hours.

Comparative example 2:

the same procedure as in comparative example 1 was followed except that the amount of polysiloxane monomer (PDMS-55) added was changed to 202g, and the amount of methylene chloride added was changed to 22848g, while the others remained the same.

The polycarbonate-polyorganosiloxane copolymer products prepared in the respective examples were subjected to tests of molecular weight, siloxane content, melt index and powder heat resistance YI value, and the results are shown in Table 2:

TABLE 2 product Performance testing

[ examples 9 to 16 ]

Starting from the copolymer prepared in each example and a commercially available polycarbonate-polyorganosiloxane copolymer product, respectively, a resin composition was prepared according to the following formulation such that the siloxane content in the composition after blending was 3.6%:

polycarbonate-polyorganosiloxane copolymer powder and a certain amount of

General-purpose PC resin,

General-purpose PC resin, an antioxidant (Irgafos 168 available from Ciba-Geigy) and a mold release agent (GlycolubeR P-ETS available from Lonza) were thoroughly mixed, and then extruded and pelletized at 280 ℃ using a coblon CTE35 type extruder, and the obtained pellets were injection molded and subjected to low-temperature impact resistance and heat resistance tests, the results of which are shown in table 3.

TABLE 3 Performance testing of resin combinations

	Impact properties at 50 ℃ (J/m)	Heat resistant molecular weight (g/mol)
			Example 10	650	150
Example 11	600	200
			Example 12	660	158
Example 13	500	163
			Example 14	550	178
Example 15	680	223
			Example 16	750	256
Example 17	620	189
			Example 18	685	267
Comparative example 4	480	480
			Comparative example 5	400	360
Comparative example 6	420	320

As can be seen from the comparison of the above data, the polysiloxane-polycarbonate copolymer prepared according to the present invention has a low oligomer content and a high polymer content, and the copolymer is more excellent in heat resistance and yellowing resistance, and the polycarbonate resin composition comprising the polycarbonate-polyorganosiloxane copolymer prepared according to the present invention has excellent low-temperature impact resistance and heat 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.

Claims

1. A polycarbonate-polyorganosiloxane copolymer, comprising polyorganosiloxane segments and polycarbonate segments, and having the following structural features:

b. the polycarbonate chain segment comprises a structural unit shown in a formula I; the polyorganosiloxane chain segment comprises a structural unit shown as a formula II;

wherein R is ₁ And R ₂ Each independently selected from hydrogen, halogen, C1-20 alkyl, C4-20 cycloalkyl or C6-20 aryl; a and b independently represent an integer of 0 to 4; x is present or absent, and when present, represents an ether group, a carbonyl group, a sulfide group, a sulfone group, a sulfoxide group, an alkylene group having 1 to 20 carbon atoms, an arylene group having 6 to 20 carbon atoms, an alicyclic group having 6 to 20 carbon atoms or

A group represented by (a); wherein R 'and R' are each independently an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 4 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms; or, R 'and R' together form a carbon number 4-20 alicyclic ring, which carbon number 4-20 alicyclic ring may be optionally substituted with one or more carbon number 1-20 alkyl groups, carbon number 6-20 aryl groups, carbon number 7-21 aralkyl groups, carbon number 5-20 cycloalkyl groups, or combinations thereof;

n ₁ selected from integers of 20 to 150, preferably 30 to 90.

2. The polycarbonate-polyorganosiloxane copolymer according to claim 1, wherein the total content by mass of the polyorganosiloxane segments in the copolymer is 5 to 40%.

3. The polycarbonate-polyorganosiloxane copolymer according to claim 1 or 2, wherein the polycarbonate segment is a structural unit derived from bisphenol a represented by formula iii:

4. the polycarbonate-polyorganosiloxane copolymer according to claim 1 or 2, wherein the polyorganosiloxane segment is a structural unit derived from a phenolic hydroxyl group-terminated polydimethylsiloxane; the phenolic hydroxyl group is derived from a phenol having an ethylenically unsaturated carbon-carbon bond, preferably any of allylphenol, eugenol, vinylphenol or isopropenylphenol, more preferably allylphenol or eugenol.

5. The method for preparing a polycarbonate-polyorganosiloxane copolymer according to any one of claims 1 to 4, comprising the steps of:

1) step A: adding a salt solution of alkali metal hydroxide of a diphenol compound, phosgene, an inert organic solvent and a phenolic hydroxyl terminated polysiloxane monomer into a polymerization reactor for reaction to obtain an oligomer mixed solution, and separating oil phase and water phase of the oligomer mixed solution to obtain an oil phase and a water phase;

2) and a step B: adding a catalyst solution and a blocking agent solution into the oil phase obtained in the step A, and uniformly mixing; adding an aqueous solution of an alkali metal hydroxide to the aqueous phase obtained in step A;

3) and a step C: mixing the oil phase and the water phase obtained in the step B, and completing polymerization reaction under stirring to obtain siloxane copolycarbonate solution;

4) step D: and (C) washing and purifying the copolymer solution prepared in the step (C) and removing the organic solvent to obtain the polycarbonate-polyorganosiloxane copolymer.

6. The process according to claim 5, wherein the amount of the alkali metal hydroxide added to the aqueous phase in the step B is such that the pH of the aqueous phase after completion of the polymerization in the step C is kept at 11 to 12.9, preferably 11.5 to 12.5.

7. The production method according to claim 5 or 6, characterized in that the salt solution of the alkali metal hydroxide of the bisphenol compound is prepared by dissolving the bisphenol compound in an aqueous solution of the alkali metal hydroxide, at a concentration of preferably 150-200g/L, more preferably 160-170g/L, based on the mass concentration of the bisphenol compound; the mass concentration of the alkali metal hydroxide is 5.6-5.9%, preferably 5.65-5.85%; the bisphenol compound is preferably one or more of 2, 2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 1-bis (4-hydroxyphenyl) ethane, 2-bis (4-hydroxy-3, 5-dimethylphenyl) propane, 4' -dihydroxybiphenyl, 2-bis (4-hydroxyphenyl) butane, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) diphenylmethane, 2-bis (4-hydroxy-3-methylphenyl) propane, and bis (4-hydroxyphenyl) naphthylmethane;

preferably, the phenolic hydroxyl terminated polysiloxane monomer is obtained by carrying out double-terminated reaction on phenols with olefinic unsaturated carbon-carbon bonds and polydimethylsiloxane; the phenols are preferably one or more of allyl phenol, eugenol, vinyl phenol and isopropenyl phenol;

preferably, the end-capping agent is one or more of phenol, p-cumylphenol, p-methylphenol, p-isopropylphenol, p-tert-butylphenol, p-cyanophenol, preferably p-tert-butylphenol or p-cumylphenol; the mass concentration of the end-capping reagent solution is preferably 10-20%, more preferably 10-15%;

preferably, the catalyst is selected from one or more of triethylamine, tetrabutylammonium bromide and tetrabutylammonium chloride, preferably triethylamine; the concentration of the catalyst solution is preferably 1 to 10%, more preferably 2 to 5%;

preferably, the alkali metal hydroxide in step 2) is one or more of potassium hydroxide, sodium hydroxide, lithium hydroxide and cesium hydroxide, and is preferably sodium hydroxide; the mass concentration of the aqueous solution of the alkali metal hydroxide is preferably 25 to 40%, more preferably 30 to 35%;

preferably, the inert organic solvent is one or more of dichloromethane, trichloromethane, dichloroethane, trichloroethane, preferably dichloromethane.

8. The production method according to claim 5, wherein the initial phosgene amount during the polymerization reaction is 1.01 to 1.3, preferably 1.1 to 1.15 in terms of a molar ratio of the bisphenol compound to phosgene;

the molar ratio of the bisphenol compound to the end-capping reagent is 20 to 40, preferably 27 to 30;

the dosage of the catalyst is 1-10 per mill, preferably 3-6 per mill of the molar quantity of the bisphenol compound;

9. The method of claim 5, wherein the oligomer polymerized in the step A has a weight average molecular weight of 1000-4000g/mol, preferably 1500-3000 g/mol.

10. A polycarbonate resin composition comprising the polycarbonate-polyorganosiloxane copolymer according to any one of claims 1 to 4 or the polycarbonate-polyorganosiloxane copolymer produced by the method according to any one of claims 5 to 9, and optionally an aromatic polycarbonate, wherein the polycarbonate-polyorganosiloxane copolymer is present in an amount of 1 to 100% by mass and the aromatic polycarbonate is present in an amount of 0 to 99% by mass;

preferably, the aromatic polycarbonate is a siloxane-free polycarbonate;

preferably, the polycarbonate resin composition further comprises 0 to 5 wt% of at least any one selected from the group consisting of a mold release agent, a flow aid, a heat stabilizer, an antioxidant, a UV absorber, an IR absorber, a flame retardant, an antistatic agent, a dye, a pigment, and a filler, based on the total weight of the polycarbonate-polyorganosiloxane copolymer and the aromatic polycarbonate.