A heat-resistant PLA copolymer polycarbonate and its preparation method

Abstract

A heat-resistant PLA copolymer polycarbonate and its preparation method, belonging to the technical field of polycarbonate materials. It has the following structure: A n ‑C, where A is a PLA copolycarbonate chain, n is 3 to 20, and C is a multi-arm macroinitiator residue. The PLA copolycarbonate chain is a copolymer of an epoxy compound, carbon dioxide, polylactic acid, and any cyclic anhydride. The present invention constructs a PLA copolycarbonate system with a three-dimensional network through molecular topological design. This solution aims to break through the performance ceiling of traditional blending and modification methods, achieving a synergistic improvement in the material's heat resistance and light transmittance. The glass transition temperature can be further increased by 3°C to 5°C compared to a linear copolymer of the same monomer, and the light transmittance reaches over 90%.

Description

Technical Field

[0001] The invention belongs to the technical field of polycarbonate materials, and particularly relates to a heat-resistant PLA copolymer polycarbonate and a preparation method thereof. Background Art

[0002] With the rapid development of polymer materials technology in recent years, cross-linked products of polylactic acid (PLA) and polycarbonate, thanks to their biodegradable properties, have shown promising applications in packaging, electronics, and 3D printing. However, the overall performance of existing materials is still limited by shortcomings in the preparation process and component compatibility issues, necessitating technological innovation to achieve performance breakthroughs.

[0003] For example, patent CN104693709B improves the processing thermal stability of PLA / PC through a two-step blending method combined with an end-group modifier. However, experimental data shows that the tensile strength retention rate of the resulting material at temperatures above 80°C is less than 60%, indicating that the blended material has insufficient temperature resistance.

[0004] Patent CN116535625A utilizes a copolymerization strategy of PPC-P and PLA. While the introduction of a CO2-based monomer improves environmental friendliness, its linear molecular chain results in low melt strength (<5 cN), making it difficult to meet diverse molding requirements. Furthermore, the polarity difference between the rigid benzene ring structure and PLA results in a transmittance of less than 75%, far below the standard for optical-grade materials. This molecular structure restricts material performance, limiting its expansion into high-end applications. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a heat-resistant PLA copolymer polycarbonate with uniform structure and high transparency and a preparation method thereof.

[0006] The technical solution adopted by the present invention to solve the technical problem is: heat-resistant PLA copolymer polycarbonate, characterized in that it has the following structure: A n -C, wherein A is a PLA copolycarbonate chain, n is 3 to 20, and C is a multi-arm macroinitiator residue. The PLA copolycarbonate chain is a copolymer of an epoxy compound, carbon dioxide, polylactic acid (PLA) and any cyclic anhydride.

[0007] This invention, through molecular topology design, constructs a three-dimensional PLA co-polycarbonate. This approach aims to break through the performance ceiling of traditional blending and modification methods, achieving a synergistic improvement in the material's heat resistance and light transmittance. Compared to linear copolymers with the same monomer structure, the glass transition temperature can be further increased by 3°C to 5°C, while the light transmittance reaches over 90%.

[0008] Preferably, the PLA copolycarbonate chain segments include: 、 、 and any , R and R1 are H, C1~C20 alkyl, alkene or aryl, and R2 is C1~C20 alkyl, alkene or aryl.

[0009] Preferably, in the above-mentioned heat-resistant PLA copolycarbonate, the epoxy compound is one or a combination of two or more C2-C20 alkylene oxides.

[0010] Preferably, in the heat-resistant PLA copolycarbonate, the epoxy compound is a combination of ethylene oxide and one or more C3-C20 alkylene oxides. This achieves a balance between flexibility and rigidity, allowing the material to maintain a certain degree of flexibility while improving its heat resistance. The copolymerization of ethylene oxide and C3-C20 alkylene oxides can also effectively reduce the crystalline regions in the molecular chain, reducing light scattering and thus improving the transparency of the material. More preferably, the molar percentage of ethylene oxide in the epoxy compound is 60% to 70%.

[0011] The C3~C20 alkylene oxide is one or a combination of two or more of propylene oxide, epichlorohydrin, 1,2-butylene oxide, cyclopentane oxide, cyclohexane oxide, 1,2-epoxyheptane, 1,2-epoxydodecane, and AGE.

[0012] Preferably, in the heat-resistant PLA copolycarbonate, the weight-average molecular weight of the polylactic acid is 2000 g / mol to 30 W g / mol, and the molecular weight distribution index is 1.9 to 2.5. The high-molecular-weight polylactic acid breaks and repolymerizes during the copolymerization process of the present invention, forming a randomly arranged polylactic acid block structure on the molecular chain. Polylactic acid with a broad molecular weight distribution is selected as the reactant. Low-molecular-weight PLA has a high density of terminal hydroxyl / carboxylic acid groups, which preferentially reacts rapidly with monomers such as epoxy compounds and carbon dioxide to form a "seed" structure of polycarbonate-PLA blocks, accelerating the copolymerization process. The longer-chain PLA, on the other hand, extends the block length through a slow insertion reaction, forming an alternating sequence distribution with the polycarbonate chain, achieving a molecular-level topological structural design. PLA blocks of different lengths (coexistence of short and long chains) can disrupt the regular arrangement of polycarbonate chains, reduce the tendency of microphase separation, and form a uniform amorphous structure inside the material, resulting in higher light transmittance. At the same time, the chemical bonding between the PLA blocks and the polycarbonate chains eliminates the difference in interfacial refractive index. Combined with the asymmetric chain length distribution of wide-distribution PLA, crystallization and light scattering are further suppressed, resulting in a haze of <5%.

[0013] Furthermore, the low-molecular-weight PLA blocks in the present invention impart local flexibility to the material, which can alleviate the thermal stress concentration of the rigid polycarbonate skeleton, thereby increasing the glass transition temperature (Tg) while avoiding high-temperature brittle cracking. The long PLA blocks form dynamic physical crosslinks with the polycarbonate network through intermolecular entanglement, restricting chain segment movement and achieving a higher tensile strength retention rate at 80°C (>80%, compared to <60% for traditional blended materials).

[0014] In the heat-resistant PLA copolycarbonate, the dianhydride can be an aromatic anhydride, such as phthalic anhydride, or an aliphatic anhydride. Preferably, the dianhydride is one or a combination of succinic anhydride, glutaric anhydride, adipic anhydride, pimelic anhydride, or suberic anhydride. The linear methylene chains (-CH2-) of the aliphatic dianhydride act as "flexible spacers" in the copolymer backbone, mitigating the rigidity difference between the PLA blocks and the polycarbonate backbone, reducing the material's brittleness while maintaining dimensional stability at high temperatures through molecular chain entanglement. More preferably, the dianhydride is a long-chain anhydride, such as pimelic anhydride or suberic anhydride. The flexible segments of these chains can absorb thermal stress, reducing the propagation of microcracks caused by internal stress at high temperatures, and further improving the 80°C tensile strength retention.

[0015] Preferably, the above A n -C structure, the general formula of C is R(-L) n , R(-L) n It is an n-valent anionic group derived from A aliphatic or aromatic organic polycarboxylic acid that does not contain nitrogen, 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; 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).

[0016] More preferably, the C is an aliphatic organic polycarboxylic acid that does not contain nitrogen, for example:

[0017] and

[0018] One or a combination of both.

[0019] During the copolymerization process of the present material, nitrogen-free aliphatic polycarboxylic acid onium salts are preferred as initiators. They provide multiple carboxylic acid groups (-COO⁻) as efficient initiation sites, allowing precise reactions with epoxy compounds and PLA to form a multi-arm topology, ensuring copolymerization selectivity exceeding 95%. The aliphatic hydrocarbon groups enhance high-temperature stability through molecular chain entanglement, while the flexible chain segments inhibit crystallization, resulting in improved light transmittance compared to aromatic initiators (which suffer from reduced light transmittance due to benzene ring conjugation). The refractive index of the R group (approximately 1.45) is close to that of PLA (approximately 1.46) and polycarbonate (approximately 1.58), reducing interfacial light scattering and achieving a haze of less than 3%. Furthermore, the flexible aliphatic chain initiator reduces melt viscosity (melt index >20g / 10min), making it suitable for blow molding and 3D printing processes.

[0020] Optional, the above A n -C structure, the C is:

[0021] 、

[0022] 、

[0023] and

[0024] One, two or more of the above. Meeting the multi-arm triggering requirements of the present invention.

[0025] Optional, the above A n -C structure, the C is:

[0026] 、

[0027] 、

[0028] 、

[0029] and

[0030] One, two or more of the above. Meeting the multi-arm triggering requirements of the present invention.

[0031] Optional, the above A n -C structure, the C is:

[0032] ,

[0033]

[0034] and

[0035] One, two or more of the above. Meeting the multi-arm triggering requirements of the present invention.

[0036] A method for preparing the above-mentioned heat-resistant PLA copolycarbonate comprises the following steps: directly placing an epoxy compound, polylactic acid, a catalyst, a multi-head initiator and any dianhydride into a high-pressure reactor, introducing carbon dioxide until the pressure reaches 0.5 MPa to 4.0 MPa, carrying out a polymerization reaction at 40°C to 100°C, and performing post-treatment after reacting for 5 to 20 hours to obtain the product.

[0037] The molar ratio of the epoxy compound, the catalyst and the multi-head initiator is 10:0.001-0.003:0.001-0.005.

[0038] The mass ratio of the epoxy compound to the polylactic acid is 100:1-90, preferably 100:5-30.

[0039] The catalyst can be a traditional metal catalyst or an organoboron compound that does not introduce metal ions. Examples of such metal catalysts include zinc-based catalyst systems, metalloporphyrin-based catalyst systems, β-diimine metal complex catalysts, double metal cyanide complex catalysts, SalenMX catalyst systems, rare earth catalyst systems, and multimetallic catalyst systems. These catalysts can meet basic catalytic copolymerization requirements to a certain extent.

[0040] Preferably, the catalyst is a composite trialkylboron catalyst, comprising triethylboron (TEB), tributylboron (TBB), and triisopropanolamine (TiPA) in a molar ratio of 1:0.5-1.5:0.08-0.12. TEB serves as the primary catalyst, rapidly initiating the ring-opening copolymerization of ethylene oxide and carbon dioxide. It exhibits outstanding activity at low temperatures (40°C-50°C) and a shortened induction period (<30 minutes). TBB offers excellent solubility and stable dispersion in high-pressure CO₂ environments, reducing the risk of catalyst deactivation. The addition ratio should be gradually increased as the CO₂ pressure increases (e.g., >3.5 MPa). TiPA acts as a proton donor, forming boron-nitrogen coordination active centers with TEB / TBB, accelerating the participation of the hydroxyl groups at the PLA terminals in the copolymerization reaction and regulating the PLA block incorporation rate (>90%). This ensures a balance between chain growth and PLA incorporation, preventing premature PLA chain termination and resulting in a PLA block incorporation rate >85% (compared to <75% for conventional single catalysts). When the composite trialkyl boron catalyst is used, the product molecular weight (Mn) can be controlled between 20 and 50, and the PDI is less than 1.3.

[0041] Under the preferred catalytic initiation system of the present invention, PLA does not need to be pre-dissolved into a homogeneous solution and can be directly added to the reaction system of the multi-arm polycarbonate. During the copolymerization process, PLA dissolves and breaks while participating in the copolymerization to obtain a high molecular weight multi-arm PLA copolymer polycarbonate, forming randomly distributed block PLA segments on the molecular chain.

[0042] Compared with existing technologies, the heat-resistant PLA copolycarbonate and its preparation method of the present invention offer the following benefits: Through molecular topology design, the material achieves a synergistic improvement in both heat resistance and light transmittance, raising the glass transition temperature by 3°C to 5°C, increasing light transmittance to over 90%, and reducing haze to less than 5%. An optimized combination of polycarbonate and PLA balances flexibility and rigidity, further enhancing transparency. The synergistic effect of low-molecular-weight PLA blocks and long PLA blocks improves the material's tensile strength retention (>80% at 80°C) while suppressing crystallization and light scattering. The use of a multi-arm macromolecular initiator enhances copolymerization selectivity (>95%) and reduces melt viscosity, making it suitable for blow molding and 3D printing processes. A composite trialkyl boron catalyst increases the PLA block access rate (>85%), controls the product molecular weight distribution (PDI <1.3), and improves material performance. DETAILED DESCRIPTION

[0043] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0044] Example 1

[0045] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and glutaric anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, composite trialkyl boron catalyst, ( The molar ratio of polylactic acid to glutaric anhydride is 6.5:3.5:0.001:0.002:1.2, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:0.8:0.1, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 2.5.

[0046] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 45 Wg / mol.

[0047] Example 2

[0048] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and glutaric anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, composite trialkyl boron catalyst, ( The molar ratio of polylactic acid to glutaric anhydride is 6.5:3.5:0.001:0.002:1.2, the molar ratio of TEB to TBB in the composite trialkyl boron catalyst is 1:0.8, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 2.5.

[0049] Carbon dioxide was introduced to a pressure of 2.8 MPa, and polymerization was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 41 Wg / mol.

[0050] Example 3

[0051] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, and mix polylactic acid, epoxy compound, TEB, and glutaric anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, TEB, ( The molar ratio of polylactic acid to glutaric anhydride is 6.5:3.5:0.001:0.002:1.2, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 2.5.

[0052] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 33 Wg / mol.

[0053] Example 4

[0054] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and glutaric anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, composite trialkyl boron catalyst, ( The molar ratio of polylactic acid to glutaric anhydride is 6.5:3.5:0.001:0.002:1.2, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:0.8:0.1, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 1.1.

[0055] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 38 Wg / mol.

[0056] Example 5

[0057] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and glutaric anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, composite trialkyl boron catalyst, The molar ratio of polylactic acid to glutaric anhydride is 6.5:3.5:0.001:0.002:1.2, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:0.8:0.1, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 2.5.

[0058] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 36 Wg / mol.

[0059] Example 6

[0060] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and glutaric anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, composite trialkyl boron catalyst, The molar ratio of polylactic acid to glutaric anhydride is 6.5:3.5:0.001:0.002:1.2, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:0.8:0.1, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 2.5.

[0061] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 43 Wg / mol.

[0062] Example 7

[0063] Prepare epoxy compound and polylactic acid in a mass ratio of 100:20, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and phthalic anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-epoxydodecane, ethylene oxide, 1,2-epoxydodecane, composite trialkyl boron catalyst, The molar ratio of polylactic acid to phthalic anhydride is 6.5:3.5:0.001:0.002:1.2, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:0.8:0.1, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 2.5.

[0064] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 43 Wg / mol.

[0065] Example 8

[0066] Prepare epoxy compound and polylactic acid in a mass ratio of 100:5, polylactic acid, epoxy compound, composite trialkyl boron catalyst and Put into the high pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and 1,2-butylene oxide, ethylene oxide, 1,2-butylene oxide, composite trialkyl boron catalyst and The molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 6:4:0.001:0.003, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:0.5:0.08, the weight average molecular weight of polylactic acid is 2000 g / mol, and the molecular weight distribution index is 2.2.

[0067] Carbon dioxide was introduced to a pressure of 2.5 MPa, and polymerization was carried out at 40°C. A PLA homogeneous solution was added in portions during the polymerization process. After 5 hours of reaction, the mixture was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 7800 g / mol.

[0068] Example 9

[0069] Prepare epoxy compound and polylactic acid in a mass ratio of 100:30, add polylactic acid, epoxy compound, composite trialkyl boron catalyst, and phthalic anhydride are put into a high-pressure reactor, wherein the epoxy compound is a mixture of ethylene oxide and propylene oxide, ethylene oxide, propylene oxide, composite trialkyl boron catalyst, The molar ratio of polylactic acid to phthalic anhydride is 7:3:0.001:0.001:3, the molar ratio of TEB, TBB and TiPA in the composite trialkyl boron catalyst is 1:1.5:0.12, the weight average molecular weight of polylactic acid is 10000 g / mol, and the molecular weight distribution index is 1.9.

[0070] Carbon dioxide is introduced until the pressure reaches 4.0 MPa, and the polymerization reaction is carried out at 70°C. During the polymerization process, a PLA homogeneous solution is added in portions. After reacting for 20 hours, the material is discharged, washed with ethanol, and then fed into a devolatilizer to remove small molecular impurities.

[0071] The weight average molecular weight of the obtained PLA copolymer modified polycarbonate was detected to be 90Wg / mol.

[0072] Comparative Example 1

[0073] The epoxy compound and polylactic acid were prepared in a mass ratio of 100:20, and the polylactic acid, epoxy compound, TEB, tetra-n-butylammonium chloride and glutaric anhydride were put into a high-pressure reactor, wherein the epoxy compound was a mixture of ethylene oxide and 1,2-epoxydodecane, and the molar ratio of ethylene oxide, 1,2-epoxydodecane, TEB, tetra-n-butylammonium chloride and glutaric anhydride was 6.5:3.5:0.001:0.002:1.2. The weight average molecular weight of the polylactic acid was 1000 g / mol, and the molecular weight distribution index was 2.5.

[0074] Carbon dioxide was introduced to a pressure of 2.8 MPa, and a polymerization reaction was carried out at 45°C. The prepared PLA homogeneous solution was added in portions during the polymerization process. After 16 hours of reaction, the solution was discharged, washed with ethanol, and then added to a devolatilizer to remove small molecular weight impurities. The resulting PLA copolymer-modified polycarbonate had a weight-average molecular weight of 8 Wg / mol.

[0075] Comparative Example 2

[0076] The process and material ratio were the same as those in Example 1, except that no polylactic acid was added for copolymerization, which served as a blank control example.

[0077] Comparative Example 3

[0078] The process and material ratio are the same as those of Comparative Example 2, except that after obtaining the copolymer, an equal amount of polylactic acid from the same batch as in Example 1 is added and blended using a twin-screw extruder at 170° C. (without adding other modifying materials) to obtain a composition.

[0079] The performance test results of the copolymer materials obtained in Examples 1 to 7 and Comparative Example 1 are shown in Table 1.

[0080] Table 1 Performance test results

[0081] .

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing a heat-resistant PLA copolycarbonate, characterized in that: Has the following structure: A n -C, wherein A is a PLA copolycarbonate chain, n is 3 to 20, and C is a multi-arm macroinitiator residue, wherein the PLA copolycarbonate chain is a copolymer of an epoxy compound, carbon dioxide, polylactic acid, and any cyclic anhydride, and the epoxy compound is one or a combination of two or more of ethylene oxide and C3 to C20 alkylene oxides; The A n The general formula of C in -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: a hydroxyaromatic carboxylic acid, or E: a nitrogen-containing aliphatic or aromatic organic polycarboxylic acid; R: an aliphatic hydrocarbon group, an aromatic hydrocarbon group, a nitrogen-containing aliphatic hydrocarbon group or a nitrogen-containing aromatic hydrocarbon group, and -L: -COO- or -O-; The method comprises the following steps: directly putting an epoxy compound, polylactic acid, a catalyst, a multi-arm macromolecular initiator and any cyclic acid anhydride into a high-pressure reactor, introducing carbon dioxide until the pressure reaches 0.5 MPa-4.0 MPa, carrying out polymerization reaction at 40-100° C., and performing post-treatment after reacting for 5-20 hours to obtain the product; the catalyst is a composite trialkyl boron catalyst, which is a composite catalyst of triethyl boron (TEB), tributyl boron (TBB) and TiPA in a molar ratio of 1:0.5-1.5:0.08-0.

12.

2. The method for preparing a heat-resistant PLA copolycarbonate according to claim 1, wherein: The segments of the PLA copolycarbonate chain include: 、 、 and any , R and R1 are H, C1~C20 alkyl, alkene or aryl, and R2 is C1~C20 alkyl, alkene or aryl.

3. The method for preparing a heat-resistant PLA copolycarbonate according to claim 1, wherein: The number average molecular weight of the polylactic acid is 2000-30W.

4. The method for preparing a heat-resistant PLA copolycarbonate according to claim 1, wherein: The cyclic anhydride includes one or a combination of two or more of phthalic anhydride, 1,8-naphthalene anhydride, succinic anhydride, glutaric anhydride and adipic anhydride.

5. The method for preparing a heat-resistant PLA copolycarbonate according to claim 1, wherein: The C is: and One or a combination of both.

6. The method for preparing a heat-resistant PLA copolycarbonate according to claim 1, wherein: The C is: 、 、 、 、 、 、 、 、 、 、 One or two or more of the following.

Images