A polycarbonate type plasticizer

Abstract

A polycarbonate plasticizer and a preparation method thereof, belonging to the technical field of material modification additives. The plasticizer has the following structure: A n —C, wherein A is a polycarbonate chain, n is 2 to 4, and C is a multi-head initiator residue; the polycarbonate chain is a block structure of a rigid segment and a flexible segment, one end of the rigid segment is connected to the multi-head initiator residue, and the other end of the rigid segment is connected to the flexible segment, the rigid segment is a PE segment polymerized from epoxy compound and phthalic anhydride or / and a polycarbonate segment of cyclohexene oxide and CO2; the flexible segment is a polycarbonate segment of BGE and CO2, a polycarbonate segment of AGE and CO2, and one or more of PEO and PPO. The plasticizer not only has excellent plasticizing effect and long-term stability, but also has low migration and good environmental adaptability.

Description

Technical Field

[0001] The invention belongs to the technical field of material modification additives, and particularly relates to a polycarbonate type plasticizer. Background Art

[0002] Polyvinyl chloride (PVC) is a widely used plastic material, and plasticizers are usually added during its processing to improve its flexibility and processing performance. Traditional plasticizers, such as phthalates, have good plasticizing effects, but they have problems such as easy precipitation, poor durability, potential toxicity and carcinogenicity, which limit their application in high-demand fields such as food packaging and medical devices.

[0003] Secondly, with the improvement of environmental protection and health awareness, higher requirements are placed on the environmental performance and safety of plasticizers. For example, patent CN201611237288.X describes a compound with both a benzoate structure and a polyvinyl chloride-like structure as a plasticizer, aiming to solve the migration problem of traditional plasticizers and potential harm to human health. However, this type of plasticizer may still have a certain degree of migration risk during high temperature or long-term use, and its application in large-scale production may be limited due to its high cost. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a polycarbonate plasticizer with better compatibility with the processing temperature of PVC and a preparation method thereof.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a polycarbonate plasticizer, characterized in that it has the following structure: A n —C, wherein A is a polycarbonate chain, n is 2 to 4, and C is a multi-head initiator residue; the polycarbonate chain is a block structure of a rigid segment and a flexible segment, one end of the rigid segment is connected to the multi-head initiator residue, and the other end of the rigid segment is connected to the flexible segment, the rigid segment is a PE segment polymerized from an epoxy compound and phthalic anhydride or / and a polycarbonate segment from cyclohexene oxide and CO2; the flexible segment is a polycarbonate segment from BGE and CO2, a polycarbonate segment from AGE and CO2, and one or more of PEO and PPO.

[0006] The invention provides a novel polycarbonate plasticizer for PVC, which has a star-shaped structure, wherein the rigid segments are centrally connected to the multi-head initiator residues, and the outer side is a flexible segment. The plasticizer not only has excellent plasticizing effect and long-term stability, but also has low migration and good environmental adaptability. Through innovative molecular design, the plasticizer can significantly reduce the potential risks to human body and environment while maintaining the flexibility and processing performance of PVC materials, thus meeting the demand of modern industry for high-performance and environmentally friendly plasticizers.

[0007] Preferably, in the above-mentioned polycarbonate plasticizer, the number average molecular weight of the polycarbonate chain is 2000-12W. The preferred molecular weight can meet the plasticization requirements of most PVC. More preferably, the number average molecular weight of the polycarbonate chain is 4W-8W, which is suitable for PVC applications with higher requirements for ductility.

[0008] Preferably, in the above-mentioned polycarbonate plasticizer, the structural formula of the polycarbonate chain is:

[0009] ,

[0010] Wherein, a, b, c, d are all integers, and 1≤a+b+c≤80, 1≤d+e≤95; R1 is hydrogen or C1~C14 alkyl, R2 is hydrogen or methyl, and R3 is butyl, C12 alkyl or C14 alkyl.

[0011] Preferably, in the structural formula of the polycarbonate chain, the ratio of a+b+c to d+e is 1:1.2-1.5. When the ratio of the outer flexible segment is adjusted to be slightly higher than that of the inner rigid segment, the plasticizer exhibits better flexibility.

[0012] Preferably, in the above polycarbonate plasticizer, the general formula of C is R(-L) n , R(-L) n It is an n-valent anionic group derived from (A) a nitrogen-free aliphatic or aromatic organic polycarboxylic acid, (B) a polyphenol, (C) polyacrylic acid, acrylic acid-methacrylic acid copolymer or polymaleic acid, (D) hydroxyaromatic carboxylic acid, or (E) a nitrogen-containing aliphatic or aromatic organic polycarboxylic acid; R is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a nitrogen-containing aliphatic hydrocarbon group or a nitrogen-containing aromatic hydrocarbon group, and -L is -COO- (carboxylate) or -O- (oxygen).

[0013] Preferably, the C is:

[0014] ,

[0015] ,

[0016] and

[0017] One, two or more of the following.

[0018] Preferably, the preparation process A of the polycarbonate plasticizer is:

[0019] 1) Add cyclohexene oxide, catalyst and multi-head initiator into the reactor, introduce carbon dioxide until the pressure reaches 2.5MPa~4.0MPa, control the reaction temperature at 40℃~50℃, and carry out polymerization reaction for 5~10 hours;

[0020] 2) After nitrogen substitution in the reactor, an epoxy compound is added, wherein the epoxy compound is propylene oxide and / or ethylene oxide, and the temperature is raised to a reaction temperature of 55° C. to 75° C. and then the polymerization reaction is continued for 5 to 15 hours; and then post-treatment is performed to obtain the product.

[0021] Preferably, the preparation process B of the polycarbonate plasticizer is:

[0022] 1) Adding an epoxy compound 1, a phthalic anhydride catalyst and a multi-head initiator into a reaction kettle, wherein the epoxy compound 1 is propylene oxide and / or ethylene oxide, raising the reaction temperature to 55° C. to 75° C. and performing a polymerization reaction for 5 to 15 hours;

[0023] 2) Putting the epoxy compound 2 into a reaction kettle, wherein the epoxy compound 2 is BGE and / or AGE, introducing carbon dioxide until the pressure reaches 2.5MPa~4.0MPa, and performing polymerization reaction at 40℃~50℃ for 5~10 hours; then performing post-treatment to obtain the product.

[0024] The present invention provides two copolymerization processes, which can prepare polycarbonate plasticizers satisfying the above structure with high yield, and other molecular structures need to be adjusted in a targeted manner.

[0025] Preferably, in the preparation processes A and B of the above-mentioned polycarbonate plasticizer, the catalyst is a metal catalyst or an organic boron compound, and the metal catalyst includes a zinc catalyst system, a metal porphyrin catalyst system, a β-diimine metal complex catalyst, a double metal cyanide complex catalyst, a SalenMX catalyst system, a rare earth catalyst system, and a multi-metal catalyst system.

[0026] Preferably, in the preparation process A of the polycarbonate plasticizer, the catalyst is triethyl boron, tripropyl boron or tributyl boron. In the preparation process A, only short alkyl organic boron needs to be selected to cooperate with the multi-head initiator to achieve high-yield copolymerization and obtain the target product with good plasticizing properties.

[0027] Preferably, in the preparation process B of the polycarbonate plasticizer, the catalyst is triethyl boron and diphenylboric acid in a molar ratio of 2.3 to 3.6:1. In the preparation process B, long-chain BGE and / or AGE need to be copolymerized with CO2 to obtain polycarbonate segments, and phthalic anhydride and epoxy compounds need to be catalyzed for copolymerization. A specific catalyst ratio is required to ensure the acquisition of the target product. Under the preferred catalyst ratio, copolymers with the desired structure can be obtained by copolymerization with high yield, and as a plasticizer, the performance is excellent.

[0028] In the above preparation process, R(-L)n is an n-valent anionic group derived from (A) a nitrogen-free aliphatic or aromatic organic polycarboxylic acid, (B) a polyphenol, (C) polyacrylic acid, acrylic acid-methacrylic acid copolymer or polymaleic acid, (D) hydroxy aromatic carboxylic acid, or (E) a nitrogen-containing aliphatic or aromatic organic polycarboxylic acid; -L is -COO- (carboxylate) or -O- (oxygen); MR'x is a cationic group ammonium ion (quaternary ammonium cation), sulfonium ion (quaternary uranium cation) or phosphonium ion (quaternary phosphonium cation) and H is a hydrogen ion (H+). R' is a C1-C30 hydrocarbon group, preferably a C2-C20 hydrocarbon group, more preferably a C2-C10 hydrocarbon group, more preferably a C2-C5 hydrocarbon group, such as ethyl, propyl or butyl.

[0029] x is 3 or 4. When MR'x is an ammonium ion (quaternary ammonium cation) or a phosphonium ion (quaternary phosphonium cation), x is 4, and when MR'x is a sulfonium ion (quaternary sarsenium cation), x is 3. M is N (nitrogen), P (phosphorus) or S (sulfur).

[0030] n is the total number of carboxylic acids and / or phenolic hydroxyl groups in the polycarboxylic acids or polyphenols (i.e., R(-L)nHn) of (A) to (E). n is generally an integer of 2 to 30, preferably 3 to 29, more preferably 4 to 28, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27.

[0031] b is an integer of 1 to 29, preferably 2 to 28, more preferably 3 to 27, for example 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26. c is an integer greater than or equal to 1 (i.e., the compound of formula I contains at least one COOH or phenolic OH group), more preferably c is 1 to 15, preferably 1 to 13, preferably 1 to 10, preferably 1 to 6, more preferably 1, 2 or 3.

[0032] Preferably, the nitrogen-free aliphatic or aromatic polycarboxylic acid (A) is (or is selected from): (A1) (hydroxyl-free or hydroxyl-containing) C6-C30 (preferably C8-C20, more preferably C10-C16) aliphatic or aromatic organic polycarboxylic acid (such as 1,4-butanedicarboxylic acid, pentane-1,3,5-tricarboxylic acid, citric acid, malic acid, o-, m-, p-terephthalic acid, benzene trimecartonic acid, pyromellitic acid, naphthalene dicarboxylic acid, naphthalene trimecartonic acid, naphthalene tetracarboxylic acid, naphthalene pentacarboxylic acid, naphthalene hexacarboxylic acid).

[0033] Preferably, the polyphenol (B) is (or is selected from) C6-C30 (preferably C6-C20) polyphenol. More preferably, the polyphenol (C) is (or is selected from): o-, m- and p-quinone, naphthalene-tetraphenol, bisphenol A, bisphenol F, bisphenol S.

[0034] Preferably, the polyacrylic acid, acrylic acid-methacrylic acid copolymer or polymaleic acid (C) is a polyacrylic acid, acrylic acid-methacrylic acid copolymer or polymaleic acid having a number average molecular weight of 220-2000 (preferably 290-1500, more preferably 350-1000 or 500-900, such as 216, 258, 348, 600, 700 or 800).

[0035] Preferably, the hydroxyaromatic carboxylic acid (D) is a hydroxyaromatic polycarboxylic acid or a polyhydroxyaromatic carboxylic acid. Preferably, the hydroxyaromatic carboxylic acid (D) is (or is selected from): hydroxyphthalic acid, ...

[0036] Preferably, the nitrogen-containing aliphatic or aromatic organic polycarboxylic acid (E) is (or is selected from): (E1) C2-C30 (preferably C3-C28, more preferably C4-C24) alkylenediaminetetra(C2-C6)carboxylic acid, or nitrilotri(C2-C6)carboxylic acid; for example, ethylenediaminetetraacetic acid, ethylenediaminetetrapropionic acid, ethylenediaminetetrabutyric acid, ethylenediaminetetrapentanoic acid, ethylenediaminetetrahexanoic acid, propylenediaminetetraacetic acid, propylenediaminetetrapropionic acid, propylenediaminetetrabutyric acid, propylenediaminetetrapentanoic acid, propylenediaminetetrahexanoic acid, butylene diamine tetraacetic acid, butanediaminetetrapropionic acid, butanediaminetetrabutyric acid, butanediaminetetrapentanoic acid, butanediaminetetrahexanoic acid, nitrilotriacetic acid, nitrilotripropionic acid, nitrilotributyric acid, nitrilotripovaleric acid, or nitrilotrihexanoic acid; or, (E2) N-C1-C4 alkyl-piperidinedicarboxylic acid (such as N-methyl-piperidine-3,5-dicarboxylic acid), N-C1-C4 alkyl-piperidinetricarboxylic acid (such as N-ethyl-piperidinetricarboxylic acid), or N-C1-C4 alkyl-piperidinetetracarboxylic acid (such as N-ethyl-piperidinetetracarboxylic acid).

[0037] Preferably, R is an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a nitrogen-containing aliphatic hydrocarbon group, or a nitrogen-containing aromatic hydrocarbon group.

[0038] According to a second embodiment of the present invention, there is provided a fully onium salted (i.e., fully salified, fully neutralized, and free of H+) multifunctional onium salt initiator (or multi-arm macromolecular initiator) having the following general formula (II):

[0039]

R(-L)n

(MR′x)n

[0040] Here, MR'x is a cationic group such as a sulfonium ion (quaternary sulfonium cation) or a phosphonium ion (quaternary phosphonium cation).

[0041] wherein R(-L)n, R, -L, M, R', n and x are as defined above.

[0042] The inventors of the present application have found that, despite being completely onium salted, the initiator of the general formula II containing a sulfonium ion (quaternary stibnium cation) or a phosphonium ion (quaternary phosphonium cation) still has a high reactivity.

[0043] According to a third embodiment of the present invention, there is provided a fully onium salted (i.e., fully salified, fully neutralized, and free of H+) multifunctional onium salt initiator (or multi-arm macromolecular initiator) having the following general formula (III):

[0044]

R(-L)n

(MR′x)n

[0045] In the formula, R(-L)n is an n-valent anionic group derived from the above-mentioned (E) nitrogen-containing aliphatic or aromatic organic polycarboxylic acid;

[0046] wherein R, -L, M, R', n and x are as defined above.

[0047] Here, MR'x is a cationic group such as ammonium ion (quaternary ammonium cation), sulfonium ion (quaternary stibnium cation) or phosphonium ion (quaternary phosphonium cation).

[0048] Since the compound of the general formula III contains N and is a Lewis base itself, it has higher activity. Therefore, even if it is completely onium salted, it still has high reactivity.

[0049] Compared with the prior art, the carbon dioxide-based surfactant polymer monomer and the preparation method thereof of the present invention have the following beneficial effects: the plasticizer of the present invention is a star-shaped elastomer, the rigid segments are centrally connected to the multi-head initiator residues, and the outer side is a flexible segment, so that the elastomer structure has very good flexibility, and the plasticizer is a polymer material, which will not precipitate after mixing with PVC, can maintain the performance of the product for a long time, and has no toxicity. The present invention uses carbon dioxide, epoxy compounds, and cyclic acid anhydrides as monomers for copolymerization, which belongs to anionic polymers, the structure of the copolymer is controllable, the processing temperature is compatible with PVC, and after blending with PVC, it can meet the requirements of improved flexibility and expansibility, uses carbon dioxide as one of the main monomers, has low cost, and achieves carbon reduction and environmental protection. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0051] Example A-1

[0052] 1) Cyclohexene oxide, triethyl boron and multi-head initiator are placed in a high pressure reactor at a molar ratio of 100:0.01:0.08, wherein the multi-head initiator is ; and introduce carbon dioxide until the pressure reaches 3.5MPa, the reaction temperature is controlled at 45°C, and the polymerization reaction is carried out for 7 hours;

[0053] 2) After nitrogen replacement in the reactor, propylene oxide is added, and the molar ratio of propylene oxide to cyclohexene oxide in step 1) is 135:100. After the temperature is raised to 65°C, the polymerization reaction is continued for 10 hours. After the reaction is complete, the reaction is terminated to obtain a glue solution; the glue solution is washed and devolatilized to obtain a copolymer. The number average molecular weight of the obtained copolymer is 20W according to nuclear magnetic resonance detection, of which the molar percentage of the PPO flexible segment is 42.6%, and the molar percentage of the polycarbonate rigid segment of cyclohexene oxide and CO2 is 57.4%.

[0054] Example A-2

[0055] 1) Cyclohexene oxide, tripropyl boron and multi-head initiator are placed in a high pressure reactor at a molar ratio of 100:0.01:0.08, wherein the multi-head initiator is ; and introduce carbon dioxide until the pressure reaches 2.5MPa, the reaction temperature is controlled at 50°C, and the polymerization reaction is carried out for 5 hours;

[0056] 2) After nitrogen replacement in the reactor, ethylene oxide is added, and the molar ratio of ethylene oxide to cyclohexene oxide in step 1) is 120:100. After the temperature is raised to 75°C, the polymerization reaction is continued for 5 hours. After the reaction is complete, the reaction is terminated to obtain a glue solution; the glue solution is washed and devolatilized to obtain a copolymer. The number average molecular weight of the obtained copolymer is 30W according to nuclear magnetic resonance detection, of which the molar percentage of the PPO flexible segment is 42.6%, and the molar percentage of the polycarbonate rigid segment of cyclohexene oxide and CO2 is 57.4%.

[0057] Example A-3

[0058] 1) Cyclohexene oxide, triethyl boron and multi-head initiator are placed in a high pressure reactor at a molar ratio of 100:0.01:0.08, wherein the multi-head initiator is , and introduce carbon dioxide until the pressure reaches 4.0MPa, the reaction temperature is controlled at 40°C, and the polymerization reaction is carried out for 10 hours;

[0059] 2) After nitrogen replacement in the reactor, propylene oxide is added, and the molar ratio of propylene oxide to cyclohexene oxide in step 1) is 150:100. After the temperature is raised to 55°C, the polymerization reaction is continued for 15 hours. After the reaction is complete, the reaction is terminated to obtain a glue solution; the glue solution is washed and devolatilized to obtain a copolymer. The number average molecular weight of the obtained copolymer is 8000 as determined by nuclear magnetic resonance, of which the molar percentage of the PPO flexible segment is 42.6%, and the molar percentage of the polycarbonate rigid segment of cyclohexene oxide and CO2 is 57.4%.

[0060] Example B-1

[0061] 1) Propylene oxide, phthalic anhydride, catalyst and multi-head initiator are added into a high-pressure reactor at a molar ratio of 100:100:0.01:0.164, and the catalyst is a composite catalyst of triethyl boron and diphenylboric acid at a molar ratio of 3.0:1; the reaction temperature is increased to 55°C~75°C and the polymerization reaction is carried out for 5~15 hours;

[0062] 2) Add AGE into the kettle, the molar ratio of propylene oxide to AGE in step 1) is 100:130, and the polymerization reaction is carried out at 40℃~50℃ for 5~10 hours; the reaction is terminated after the reaction is complete to obtain a glue solution; the glue solution is washed and devolatilized to obtain the obtained copolymer. The number average molecular weight of the obtained copolymer is 30W according to nuclear magnetic resonance detection, wherein the molar percentage of the polycarbonate soft segment of AGE and CO2 is 43.4%, and the molar percentage of the PE rigid segment polymerized by propylene oxide and phthalic anhydride is 56.6%.

[0063] Example B-2

[0064] 1) Propylene oxide and / or ethylene oxide, phthalic anhydride, catalyst and multi-head initiator are added into a high-pressure reactor in a molar ratio of 100:100:0.01:0.164, and the catalyst is a composite catalyst of triethyl boron and diphenylboric acid in a molar ratio of 3.0:1; the reaction temperature is increased to 55°C~75°C and the polymerization reaction is carried out for 5~15 hours;

[0065] 2) Add BGE into the kettle, the molar ratio of propylene oxide to BGE in step 1) is 100:130, and the polymerization reaction is carried out at 40°C~50°C for 5~10 hours; after the reaction is complete, the reaction is terminated to obtain a glue solution; the glue solution is washed and devolatilized to obtain. The number average molecular weight of the obtained copolymer is 30W according to nuclear magnetic resonance detection, of which the molar percentage of the polycarbonate soft segment of AGE and CO2 is 43.4%, and the molar percentage of the PE rigid segment polymerized by propylene oxide and phthalic anhydride is 56.6%.

[0066] Example B-3

[0067] 1) Ethylene oxide, phthalic anhydride, catalyst and multi-head initiator are added into a high-pressure reactor at a molar ratio of 100:100:0.01:0.164, and the catalyst is a composite catalyst of triethyl boron and diphenylboric acid at a molar ratio of 3.0:1; the reaction temperature is increased to 55°C~75°C and the polymerization reaction is carried out for 5~15 hours;

[0068] 2) Add AGE into the kettle, the molar ratio of ethylene oxide to AGE in step 1 is 100:130, and the polymerization reaction is carried out at 40℃~50℃ for 5~10 hours; after the reaction is complete, the reaction is terminated to obtain a glue solution; the glue solution is washed and devolatilized to obtain the obtained copolymer. The number average molecular weight of the obtained copolymer is 30W according to nuclear magnetic resonance detection, wherein the molar percentage of the polycarbonate flexible segment of AGE and CO2 is 43.4%, and the molar percentage of the PE rigid segment polymerized by propylene oxide and phthalic anhydride is 56.6%.

[0069] The plasticizers prepared in each example were added to SG3 type PVC for blending, and the addition amount was 35wt%, and the blended materials were tested for plasticization. The migration was tested by immersing the PVC material in a food simulating liquid (n-hexane) for 30 days and then measuring the content of the plasticizer in the food simulating liquid; the test results are shown in Table 1.

[0070] Table 1

[0071] .

[0072] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A polycarbonate plasticizer, characterized in that: Has the following structure: A n —C, wherein A is a polycarbonate chain, n is 2 to 4, and C is a multi-head initiator residue; the polycarbonate chain is a block structure of a rigid segment and a flexible segment, one end of the rigid segment is connected to the multi-head initiator residue, and the other end of the rigid segment is connected to the flexible segment, the rigid segment is a PE segment polymerized from an epoxy compound and phthalic anhydride or / and a polycarbonate segment from cyclohexene oxide and CO2; the flexible segment is a polycarbonate segment from BGE and CO2, or a polycarbonate segment from AGE and CO2; The C is: 、 、 and One, two or more of the following.

2. A polycarbonate plasticizer according to claim 1, characterized in that: The number average molecular weight of the polycarbonate chain is 2000-12W.

3. The polycarbonate plasticizer according to claim 1, characterized in that: The structural formula of the polycarbonate chain is: ， Wherein, a, b, c, d are all integers, and 1≤a+b≤80, 1≤c+d≤95; R1 is a C1~C14 alkyl group, R2 is hydrogen or methyl, and R3 is a butyl group, a C12 alkyl group or a C14 alkyl group.

4. A polycarbonate plasticizer according to claim 3, characterized in that: The ratio of a+b to c+d is 1:1.2~1.

5.

5. A polycarbonate plasticizer according to claim 1, characterized in that: The preparation process is: 1) Adding an epoxy compound 1, a phthalic anhydride catalyst and a multi-head initiator into a reaction kettle, wherein the epoxy compound 1 is propylene oxide and / or ethylene oxide, raising the reaction temperature to 55° C. to 75° C. and performing a polymerization reaction for 5 to 10 hours; 2) Put the epoxy compound 2 into a reaction kettle, the epoxy compound 2 is BGE and / or AGE, introduce carbon dioxide until the pressure reaches 2.5MPa~4.0MPa, carry out polymerization reaction at 40℃~50℃ for 8~15 hours; then carry out post-treatment to obtain the product.

6. A polycarbonate plasticizer according to claim 5, characterized in that: The catalyst is a metal catalyst or an organic boron compound, and the metal catalyst is a zinc catalyst system, a metal porphyrin catalyst system, a β-diimine metal complex catalyst, a double metal cyanide complex catalyst or a rare earth catalyst system.

7. A polycarbonate plasticizer according to claim 5, characterized in that: The catalyst is triethyl boron, tripropyl boron or tributyl boron.

8. A polycarbonate plasticizer according to claim 7, characterized in that: The catalyst is triethyl boron and diphenyl boric acid in a molar ratio of 2.3-3.6:1.

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