Polyethylene glycol succinate as well as synthesis method and application thereof

Abstract

The invention discloses polyethylene glycol succinate as well as a synthesis method and application thereof, and belongs to the technical field of polyethylene glycol succinate. The number-average molecular weight Mn of the polyethylene glycol succinate is 50000 g / mol to 850000 g / mol, the weight-average molecular weight Mw of the polyethylene glycol succinate is 100000 g / mol to 150000 g / mol, and the terminal carboxyl group content of the polyethylene glycol succinate is not higher than 40 mol / t. The polyethylene glycol succinate has relatively high molecular weight and relatively excellent hydrolysis resistance and aging resistance. The synthesis method comprises the following steps: carrying out esterification reaction, pre-polycondensation reaction, chain extension reaction and end capping reaction on any one of succinic anhydride and succinic acid fatty alcohol diester and ethylene glycol. The method is simple to operate, the process is easy to control, the high-molecular-weight polyethylene glycol succinate which is relatively slow in degradation speed, particularly relatively slow in water aging speed can be prepared, and the high-molecular-weight polyethylene glycol succinate is suitable for being used as a packaging material.

Description

Technical Field

[0001] The present invention relates to the technical field of polyethylene succinate, and in particular, to a polyethylene succinate, a synthesis method thereof, and an application thereof. Background Art

[0002] Polyethylene succinate is a good biodegradable polymer material, having good crystallization properties and strength properties. At the same time, compared with polylactic acid, PHA, and butanediol-based biodegradable polyesters (polyethylene succinate, PBS) that are currently popular in the market, the cost is lower.

[0003] However, the current polyethylene succinate has at least one of the following defects: the polymerization of ethylene glycol succinate itself is difficult, and the molecular weight is difficult to increase to the level required by the market; there are many side reactions in the synthesis process of polyethylene succinate, the control difficulty is large, and the degradation rate of the obtained material is too fast, especially the hydrolysis and aging rates are fast, and the market requirements for the service life of the material cannot be met.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a polyethylene succinate, a synthesis method thereof, and an application thereof to solve or improve the above technical problems.

[0006] The present invention can be implemented as follows:

[0007] In a first aspect, the present invention provides a polyethylene succinate, and the number average molecular weight M of the polyethylene succinate n is 50,000 g / mol - 850,000 g / mol, the weight average molecular weight M w is 100,000 g / mol - 1,500,000 g / mol, and the terminal carboxyl group content is not higher than 40 mol / t.

[0008] In an optional embodiment, the number average molecular weight M of the polyethylene succinate n is 50,000 g / mol - 830,000 g / mol; and / or, the weight average molecular weight M of the polyethylene succinate w is 830,000 g / mol - 1,300,000 g / mol; and / or, the terminal carboxyl group content of the polyethylene succinate is 24 mol / t - 38 mol / t.

[0009] In a second aspect, the present invention provides a synthesis method of a polyethylene succinate as described in the foregoing embodiment, including the following steps: subjecting any one of succinic anhydride and aliphatic alcohol diester of succinic acid to an esterification reaction with ethylene glycol, and performing a pre-polycondensation reaction after the esterification is completed to obtain a prepolymer of polyethylene succinate; subjecting the prepolymer to a chain extension reaction and a capping reaction.

[0010] In an alternative embodiment, the molar ratio of ethylene glycol to succinic anhydride is from 1:1 to 100:1.

[0011] In an alternative embodiment, the molar ratio of ethylene glycol to fatty alcohol disuccinate is from 1:1 to 100:1.

[0012] In an alternative embodiment, the fatty alcohol disuccinate includes at least one of dimethyl succinate, diethyl succinate, and diisopropyl succinate.

[0013] In an alternative embodiment, the esterification reaction includes at least one of the following features:

[0014] Feature 1: The temperature of the esterification reaction is 150°C - 250°C;

[0015] Feature 2: The pressure of the esterification reaction is 50 kPa - 100 kPa in absolute pressure;

[0016] Feature 3: The time of the esterification reaction is 1 h - 5 h;

[0017] Feature 4: A catalyst is used during the esterification reaction.

[0018] In an alternative embodiment, the catalyst includes an organotitanium compound.

[0019] In an alternative embodiment, the addition amount of the catalyst is 0.01% - 1% of the mass of the theoretically produced polyethylene succinate.

[0020] In an alternative embodiment, the prepolycondensation reaction includes at least one of the following features:

[0021] Feature 1: The temperature of the prepolycondensation reaction is 150°C - 250°C;

[0022] Feature 2: The pressure of the prepolycondensation reaction is 50 Pa - 10 kPa in absolute pressure;

[0023] Feature 3: The time of the prepolycondensation reaction is 1 h - 10 h.

[0024] In an alternative embodiment, the viscosity of the prepolymer obtained from the prepolycondensation reaction does not exceed 1.6 dL / g.

[0025] In an alternative embodiment, the number-average molecular weight M n of the prepolymer obtained from the prepolycondensation reaction is 25,000 g / mol - 40,000 g / mol, the weight-average molecular weight is M w is 50,000 g / mol - 80,000 g / mol, and the terminal carboxyl group content is not higher than 40 mol / t.

[0026] In an alternative embodiment, the chain extension reaction includes at least one of the following features:

[0027] Feature 1: The temperature of the chain extension reaction is 150°C - 250°C;

[0028] Feature 2: The pressure of the chain extension reaction is 0.5 MPa - 5 MPa in absolute pressure;

[0029] Feature 3: The time of the chain extension reaction is 0.1 h - 1 h;

[0030] Feature 4: The dosage of the chain extender used in the chain extension reaction is 0.01% - 1% of the mass of the theoretically produced polyethylene glycol succinate.

[0031] In an alternative embodiment, the chain extender includes at least one of diisocyanate and epoxide.

[0032] In an alternative embodiment, the diisocyanate includes hexamethylene diisocyanate.

[0033] In an alternative embodiment, the epoxide includes a styrene-methyl methacrylate-glycidyl methacrylate copolymer.

[0034] In an alternative embodiment, the end-capping reaction includes at least one of the following features:

[0035] Feature 1: The temperature of the end-capping reaction is 150°C - 250°C;

[0036] Feature 2: The pressure of the end-capping reaction is 0.1 MPa - 5 MPa in absolute pressure;

[0037] Feature 3: The time of the end-capping reaction is 0.1 h - 2 h;

[0038] Feature 4: The dosage of the end-capping agent used in the end-capping reaction is 0.01% - 1% of the mass of the theoretically produced polyethylene glycol succinate.

[0039] In an alternative embodiment, the end-capping agent includes a polyether with an epoxy functional group at the end and a molecular weight less than 5000 g / mol.

[0040] In an alternative embodiment, the end-capping agent includes at least one of polyethylene glycol ether-based glycidyl ether and propylene oxide.

[0041] In a third aspect, the present invention provides a packaging material, and the raw materials for its preparation include the polyethylene glycol succinate according to any one of the foregoing embodiments.

[0042] The beneficial effects of this application include:

[0043] This application uses succinic anhydride or fatty alcohol diester of succinic acid as raw materials, effectively reducing or avoiding the hydrolysis problem of the catalyst during the esterification reaction, and preventing the hydrolyzed catalyst from causing a large number of side reactions during the polycondensation stage; by means of a chain extension reaction, the molecular weight of the product is effectively increased, and combined with capping the terminal carboxyl groups of the molecular chains after chain extension, a polyethylene succinate with excellent hydrolysis resistance, aging resistance and a relatively high molecular weight is obtained. Detailed implementation manners

[0044] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not specified by the manufacturer are all conventional products that can be obtained by purchasing in the market.

[0045] The polyethylene succinate provided by this application, its synthesis method and application will be specifically described below.

[0046] This application provides a polyethylene succinate, the number average molecular weight M n is 50,000 g / mol - 850,000 g / mol, and the weight average molecular weight M w is 100,000 g / mol - 1,500,000 g / mol, and the terminal carboxyl group content is not higher than 40 mol / t.

[0047] For reference, the number average molecular weight M of the polyethylene succinate provided by this application n can be 50,000 g / mol, 100,000 g / mol, 150,000 g / mol, 200,000 g / mol, 250,000 g / mol, 300,000 g / mol, 350,000 g / mol, 400,000 g / mol, 450,000 g / mol, 500,000 g / mol, 550,000 g / mol, 600,000 g / mol, 650,000 g / mol, 700,000 g / mol, 750,000 g / mol, 800,000 g / mol or 850,000 g / mol, etc., or any other value within the range of 50,000 g / mol - 850,000 g / mol.

[0048] The weight average molecular weight M of the polyethylene succinate provided by this application wIt can be 100,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, 600,000 g / mol, 700,000 g / mol, 800,000 g / mol, 900,000 g / mol, 1,000,000 g / mol, 1,100,000 g / mol, 1,200,000 g / mol, 1,300,000 g / mol, 1,400,000 g / mol or 1,500,000 g / mol, etc., or any other arbitrary value within the range of 100,000 g / mol - 1,500,000 g / mol.

[0049] The carboxyl end group content of the polyethylene glycol succinate provided by this application can be 40 mol / t, 38 mol / t, 35 mol / t, 32 mol / t, 30 mol / t, 25 mol / t, 20 mol / t, 18 mol / t or 15 mol / t, etc., or other values not higher than 40 mol / t.

[0050] In some alternative embodiments, the number-average molecular weight M of the above-mentioned polyethylene glycol succinate n is 50,000 g / mol - 830,000 g / mol. In some alternative embodiments, the weight-average molecular weight M of the above-mentioned polyethylene glycol succinate w is 830,000 g / mol - 1,300,000 g / mol. In some alternative embodiments, the carboxyl end group content of the above-mentioned polyethylene glycol succinate is 24 mol / t - 38 mol / t.

[0051] In some exemplary embodiments, the number-average molecular weight M of the above-mentioned polyethylene glycol succinate n is 830,000 g / mol, the weight-average molecular weight M w is 1,300,000 g / mol, and the carboxyl end group content is 26 mol / t.

[0052] In some embodiments, the tensile strength of the above-mentioned polyethylene glycol succinate is not less than 25 MPa, the flexural modulus is not less than 500 MPa, and the elongation at break is not less than 200%.

[0053] Continuing from the above, the polyethylene glycol succinate provided by this application has a relatively high molecular weight and a relatively concentrated molecular weight distribution, and can have relatively excellent mechanical properties. In addition, the carboxyl end group content of this polyethylene glycol succinate is relatively low, and it can have relatively excellent hydrolysis resistance and aging resistance.

[0054] Accordingly, the present application also provides a method for synthesizing the above-mentioned polyethylene glycol succinate, which may include the following steps: performing an esterification reaction between any one of succinic anhydride and fatty alcohol diester of succinic acid and ethylene glycol, and performing a prepolycondensation reaction after the esterification is completed to obtain a prepolymer of polyethylene glycol succinate; performing a chain extension reaction and a capping reaction on the prepolymer.

[0055] That is, in some embodiments, succinic anhydride is used to perform an esterification reaction with ethylene glycol. In other embodiments, fatty alcohol diester of succinic acid is used to perform an esterification reaction with ethylene glycol.

[0056] It should be noted that the inventor creatively proposed that the reason why polyethylene glycol succinate in the prior art cannot have excellent hydrolysis resistance and aging resistance under the condition of high molecular weight may lie in the use of its synthesis raw materials. Currently, in the prior art, succinic acid is usually used as a raw material to synthesize polyethylene glycol succinate, and water is generated in this process, which in turn causes the catalyst used in the esterification reaction to hydrolyze, resulting in side reactions (including an increase in the reaction of forming ethers), increasing the degradation rate of the material (especially the hydrolysis rate and aging rate), and being unfavorable for synthesizing polyethylene glycol succinate with a relatively high and concentrated molecular weight.

[0057] However, in the present application, succinic anhydride or fatty alcohol diester of succinic acid is specifically used for the esterification reaction, and no water or a small amount of water is generated after the reaction with ethylene glycol (only 1 molecule of water is generated when succinic anhydride reacts with ethylene glycol, while 2 molecules of water are generated when succinic acid reacts with ethylene glycol), which can effectively avoid the above defects.

[0058] By way of reference, the molar ratio of the above ethylene glycol to succinic anhydride can be 1:1 to 100:1, such as 1:1, 2:1, 5:1, 10:1, 20:1, 50:1, 80:1 or 100:1, etc., and can also be any other value within the range of 1:1 to 100:1.

[0059] Similarly, the molar ratio of ethylene glycol to fatty alcohol diester of succinic acid can also be 1:1 to 100:1, such as 1:1, 2:1, 5:1, 10:1, 20:1, 50:1, 80:1 or 100:1, etc., and can also be any other value within the range of 1:1 to 100:1.

[0060] By way of illustration, the above-mentioned fatty alcohol diester of succinic acid may include, but is not limited to, at least one of dimethyl succinate, diethyl succinate, and diisopropyl succinate.

[0061] In this application, the temperature of the esterification reaction can be 150°C - 250°C, such as 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, etc., or it can be any other value within the range of 150°C - 250°C.

[0062] In terms of absolute pressure, the pressure of the esterification reaction can be 50 KPa - 100 Kpa, such as 5 KPa, 10 KPa, 20 KPa, 30 KPa, 40 KPa, 50 KPa, 60 KPa, 70 KPa, 80 KPa, 90 KPa or 100 KPa, etc., or it can be any other value within the range of 50 KPa - 100 Kpa.

[0063] The time of the esterification reaction can be 1 h - 5 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, etc., or it can be any other value within the range of 1 h - 5 h.

[0064] The above esterification reaction process uses a catalyst, such as an organic titanium compound. By way of example but not limitation, the organic titanium compound can include at least one of substances such as tetrabutyl titanate, tetraethanol titanate, tetrapropyl titanate, tetrabutanol titanate, tetraisopropyl titanate, tetraisobutanol titanate, and macromolecular organic chelate anti-hydrolysis titanium-based catalysts.

[0065] The addition amount of the above catalyst can be 0.01% - 1% of the mass of the theoretically produced ethylene glycol succinate, such as 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8% or 1%, etc., or it can be any other value within the range of 0.01% - 1%.

[0066] The chemical equations involved in the above esterification reaction are as follows:

[0067] CH3OOCCH2CH2COOCH3 + 2HOCH2CH2OH → HOCH2CH2OOCCH2CH2COOCH2CH2OH + 2CH3OH;

[0068] C4H4O3 + 2HOCH2CH2OH → HOCH2CH2OOCCH2CH2COOCH2CH2OH + H2O.

[0069] In this application, the temperature of the pre-polycondensation reaction can be 150°C - 250°C, such as 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, etc., or it can be any other value within the range of 150°C - 250°C.

[0070] In terms of absolute pressure, the pressure range of the prepolycondensation reaction is generally within 50 Pa - 10 KPa. During actual operation, it is divided into two pressure stages, and the pressure in the first stage is higher than that in the second stage. In some embodiments, the first-stage prepolycondensation can be carried out under the condition of 5 KPa, and then the second-stage prepolycondensation can be carried out under the condition of 100 Pa.

[0071] The time of the prepolycondensation reaction can be 1 h - 10 h, such as 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, etc., or any other arbitrary value within the range of 1 h - 10 h.

[0072] In some embodiments, the viscosity of the prepolymer obtained from the prepolycondensation reaction does not exceed 1.6 dL / g. In other words, the degree and end time of the prepolycondensation can be determined by monitoring the viscosity of the prepolymer.

[0073] For reference, the number-average molecular weight M n of the prepolymer obtained from the prepolycondensation reaction is 25000 g / mol - 40000 g / mol, the weight-average molecular weight is M w is 50000 g / mol - 80000 g / mol, and the terminal carboxyl group content is not higher than 40 mol / t.

[0074] By controlling the prepolymer under the above conditions, it is beneficial to obtain poly(ethylene succinate) with high molecular weight, excellent mechanical properties, hydrolysis resistance and aging resistance through subsequent chain extension reaction and end-capping reaction.

[0075] In this application, the temperature of the chain extension reaction can be 150 °C - 250 °C, such as 150 °C, 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C, 220 °C, 230 °C, 240 °C or 250 °C, etc., or any other arbitrary value within the range of 150 °C - 250 °C.

[0076] In terms of absolute pressure, the pressure of the chain extension reaction can be 0.5 MPa - 5 MPa, such as 0.5 MPa, 1 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa or 5 MPa, etc., or any other arbitrary value within the range of 0.5 MPa - 5 MPa.

[0077] The time of the chain extension reaction can be 0.1 h - 1 h, such as 0.1 h, 0.5 h, 0.8 h or 1 h, etc., or any other arbitrary value within the range of 0.1 h - 1 h.

[0078] The dosage of the chain extender used in the chain extension reaction can be 0.01% - 1% of the mass of the theoretically produced polyethylene succinate, such as 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8% or 1%, etc., or any other arbitrary value within the range of 0.01% - 1%.

[0079] For reference, the above-mentioned chain extender can exemplarily but non - restrictively include at least one of diisocyanates and epoxides. Among them, the diisocyanate can exemplarily but non - restrictively include hexamethylene diisocyanate, isophorone diisocyanate, isophorone diisocyanate, toluene diisocyanate and toluene diisocyanate, etc. The epoxide can exemplarily but non - restrictively include styrene - methyl methacrylate - glycidyl methacrylate copolymer, ethylene - acrylic acid - glycidyl methacrylate, epoxidized soybean oil, cyclohexyl glycidyl ether, benzyl glycidyl ether and furfuryl glycidyl ether, etc.

[0080] The temperature of the end - capping reaction can be 150°C - 250°C, such as 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C, etc., or any other arbitrary value within the range of 150°C - 250°C.

[0081] In terms of absolute pressure, the pressure of the end - capping reaction can be 0.1MPa - 5MPa, such as 0.1MPa, 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa or 5MPa, etc.

[0082] The time of the end - capping reaction can be 0.1h - 2h, such as 0.1h, 0.5h, 1h, 1.5h or 2h, etc.

[0083] The dosage of the end - capping agent used in the end - capping reaction can be 0.01% - 1% of the mass of the theoretically produced polyethylene succinate, such as 0.01%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8% or 1%, etc., or any other arbitrary value within the range of 0.01% - 1%.

[0084] For reference, the end - capping agent can include polyethers with an epoxy functional group at the end and a molecular weight less than 5000g / mol, for example, it can exemplarily but non - restrictively include at least one of polyethylene glycol ether - based glycidyl ether and propylene oxide.

[0085] Continuing from the above, in this application, by specifically using succinic anhydride or fatty alcohol disuccinate as raw materials, the hydrolysis problem of the catalyst during the esterification reaction is effectively reduced or avoided, preventing a large number of side reactions caused by the hydrolyzed catalyst during the polycondensation stage; by the chain extension reaction, the molecular weight of the product is effectively increased, and combined with end-capping the terminal carboxyl groups of the molecular chains after chain extension, poly(ethylene succinate) with excellent hydrolysis resistance, aging resistance, and a relatively high molecular weight is obtained.

[0086] In addition, this application also provides a packaging material, the preparation raw materials of which include the above poly(ethylene succinate). This packaging material can achieve biodegradation within a relatively appropriate time range.

[0087] The features and properties of the present invention will be further described in detail below in conjunction with examples.

[0088] Example 1

[0089] This example provides a poly(ethylene succinate), which is synthesized by the following method:

[0090] S1: Esterification reaction.

[0091] Weigh 2 kg (20 mol) of succinic anhydride, 3.1 kg (50 mol) of ethylene glycol, and 20 g of tetrabutyl titanate and add them to a reaction kettle, and carry out an esterification reaction at 200 °C and 80 KPa for 4 h.

[0092] S2: Pre-polycondensation reaction.

[0093] After the esterification reaction is completed, carry out pre-polycondensation reactions at 220 °C and 5 KPa and at 220 °C and 100 Pa for 2 h and 4 h respectively until the viscosity of the prepolymer is 1.6 dL / g.

[0094] S3: Chain extension reaction and end-capping reaction.

[0095] Add 27 g of hexamethylene diisocyanate and carry out a chain extension reaction at 220 °C and 2 MPa for 15 min; then add 13.5 g of propylene oxide and carry out an end-capping reaction at 220 °C and 2 MPa for 15 min to obtain poly(ethylene succinate).

[0096] Example 2

[0097] This example provides a poly(ethylene succinate), which is synthesized by the following method:

[0098] S1: Esterification reaction.

[0099] Weigh 2 kg (20 mol) of succinic anhydride, 3.1 kg (50 mol) of ethylene glycol and 20 g of tetrapropyl titanate and add them to the reaction kettle. Carry out the esterification reaction at 200 °C and 80 KPa for 4 h.

[0100] S2: Pre-polycondensation reaction.

[0101] After the esterification reaction, carry out the pre-polycondensation reaction for 2 h and 4 h successively at 220 °C and 5 KPa and at 220 °C and 100 Pa until the viscosity of the prepolymer is 1.6 dL / g.

[0102] S3: Chain extension reaction and end-capping reaction.

[0103] Add 25 g of ethylene-acrylic acid-glycidyl methacrylate, and carry out the chain extension reaction at 220 °C and 2 MPa for 25 min; then add 150 g of polyethylene glycol ether-based glycidyl ether with a molecular weight of 400, and carry out the end-capping reaction at 220 °C and 2 MPa for 20 min to obtain polyethylene glycol succinate.

[0104] Example 3

[0105] This example provides a polyethylene glycol succinate, which is synthesized by the following method:

[0106] S1: Esterification reaction.

[0107] Weigh 2.9 kg (20 mol) of dimethyl succinate, 3.1 kg (50 mol) of ethylene glycol and 20 g of tetra-isobutyl titanate and add them to the reaction kettle. Carry out the esterification reaction at 200 °C and 80 KPa for 4 h.

[0108] S2: Pre-polycondensation reaction.

[0109] After the esterification reaction, carry out the pre-polycondensation reaction for 2 h and 4 h successively at 220 °C and 5 KPa and at 220 °C and 100 Pa until the viscosity of the prepolymer is 1.6 dL / g.

[0110] S3: Chain extension reaction and end-capping reaction.

[0111] Add 27 g of hexamethylene diisocyanate, and carry out the chain extension reaction at 220 °C and 2 MPa for 15 min; then add 150 g of polyethylene glycol ether-based glycidyl ether with a molecular weight of 400, and carry out the end-capping reaction at 220 °C and 2 MPa for 20 min to obtain polyethylene glycol succinate.

[0112] Example 4

[0113] The difference between this example and Example 3 is that dimethyl succinate is replaced by diisopropyl succinate.

[0114] Example 5

[0115] This example provides a polyethylene glycol succinate, which is synthesized by the following method:

[0116] S1: Esterification reaction. Weigh 2 kg (20 mol) of succinic anhydride, ethylene glycol and a hydrolysis-resistant titanium-based catalyst (tetrabutyl titanate) and add them to the reaction kettle. Carry out the esterification reaction at 200 °C and 50 KPa for 2 h.

[0117] Among them, the molar ratio of ethylene glycol to succinic anhydride is 1.1:1. The addition amount of the catalyst is 0.03% of the mass of the theoretically produced polyethylene glycol succinate.

[0118] S2: Pre-polycondensation reaction.

[0119] After the esterification reaction, carry out the pre-polycondensation reaction at 210 °C and 10 KPa for 1 h and at 220 °C and 100 Pa for 2 h until the viscosity of the prepolymer is 1.6 dL / g.

[0120] S3: Chain extension reaction and end-capping reaction.

[0121] Add hexamethylene diisocyanate and carry out the chain extension reaction at 180 °C and 0.5 MPa for 0.1 h; then add propylene oxide and carry out the end-capping reaction at 180 °C and 0.5 MPa for 15 min to obtain polyethylene glycol succinate.

[0122] The addition amounts of both hexamethylene diisocyanate and the end-capping agent are 0.05% of the mass of the theoretically produced polyethylene glycol succinate.

[0123] Example 6

[0124] This example provides a polyethylene glycol succinate, which is synthesized by the following method:

[0125] S1: Esterification reaction.

[0126] Weigh 2 kg (20 mol) of succinic anhydride, ethylene glycol and a hydrolysis-resistant titanium-based catalyst (tetrabutyl titanate) and add them to the reaction kettle. Carry out the esterification reaction at 240 °C and 100 KPa for 5 h.

[0127] Among them, the molar ratio of ethylene glycol to succinic anhydride is 40:1. The addition amount of the catalyst is 0.4% of the mass of the theoretically produced polyethylene glycol succinate.

[0128] S2: Pre-polycondensation reaction.

[0129] After the esterification reaction, pre-polycondensation reactions were carried out at 240 °C and 5 KPa for 4 h and at 240 °C and 50 Pa for 6 h in sequence until the viscosity of the prepolymer reached 1.6 dL / g.

[0130] S3: Chain extension reaction and end-capping reaction.

[0131] Styrene-methyl methacrylate-glycidyl methacrylate copolymer was added, and a 1-h chain extension reaction was carried out at 230 °C and 5 MPa; subsequently, poly(ethylene glycol) ether-based glycidyl ether with a molecular weight of 2000 was added, and an end-capping reaction was carried out at 230 °C and 5 MPa for 1 h to obtain polyethylene glycol succinate.

[0132] The addition amounts of styrene-methyl methacrylate-glycidyl methacrylate copolymer and poly(ethylene glycol) ether-based glycidyl ether with a molecular weight of 2000 were both 0.7% of the mass of theoretically produced polyethylene glycol succinate.

[0133] Comparative Example 1

[0134] This comparative example provides a polyethylene glycol succinate, which is synthesized by the following method:

[0135] S1: Esterification reaction.

[0136] 2.36 kg (20 mol) of succinic acid, 3.1 kg (50 mol) of ethylene glycol and 20 g of tetrabutyl titanate were weighed and added to the reaction kettle, and an esterification reaction was carried out at 200 °C and 80 kPa for 4 hours.

[0137] S2: Pre-polycondensation reaction.

[0138] After the esterification reaction, pre-polycondensation reactions were carried out at 220 °C and 5 KPa for 2 h and at 220 °C and 100 Pa for 4 h in sequence until the viscosity of the prepolymer reached 1.6 dL / g.

[0139] S3: Melt polycondensation reaction.

[0140] After the pre-polycondensation reaction, final polycondensation was carried out at 220 °C and 50 Pa for 3 h to obtain polyethylene glycol succinate.

[0141] That is: In this comparative example, succinic acid was used as the raw material, no chain extension reaction was carried out, and the molecular weight was increased completely by melt polycondensation.

[0142] Comparative Example 2

[0143] This comparative example provides a polyethylene glycol succinate, which is synthesized by the following method:

[0144] S1: Esterification reaction.

[0145] Weigh 2 kg (20 mol) of succinic anhydride, 3.1 kg (50 mol) of ethylene glycol and 20 g of tetrabutyl titanate and add them to a reaction kettle. Carry out an esterification reaction at 200 °C and 80 KPa for 4 h.

[0146] S2: Pre-polycondensation reaction.

[0147] After the esterification reaction, carry out pre-polycondensation reactions at 220 °C and 5 KPa and then at 220 °C and 100 Pa for 2 h and 4 h respectively until the viscosity of the prepolymer reaches 1.6 dL / g.

[0148] S3: Melt polycondensation reaction.

[0149] After the pre-polycondensation reaction, carry out a final polycondensation at 220 °C and 50 Pa for 3 h to obtain polyethylene glycol succinate.

[0150] That is: In this comparative example, succinic anhydride is used as the raw material, no chain extension reaction is carried out, and the molecular weight is increased entirely by melt polycondensation.

[0151] Comparative Example 3

[0152] This comparative example provides a polyethylene glycol succinate, which is synthesized by the following method:

[0153] S1: Esterification reaction.

[0154] Weigh 2.36 kg (20 mol) of succinic acid, 3.1 kg (50 mol) of ethylene glycol and 20 g of tetrabutyl titanate and add them to a reaction kettle. Carry out an esterification reaction at 200 °C and 80 KPa for 4 h.

[0155] S2: Pre-polycondensation reaction.

[0156] After the esterification reaction, carry out pre-polycondensation reactions at 220 °C and 5 KPa and then at 220 °C and 100 Pa for 2 h and 4 h respectively until the viscosity of the prepolymer reaches 1.6 dL / g.

[0157] S3: Chain extension reaction and end-capping reaction.

[0158] Add 27 g of hexamethylene diisocyanate and carry out a chain extension reaction at 220 °C and 2 MPa for 15 min; then add 150 g of polyethylene glycol ether-based glycidyl ether with a molecular weight of 400 and carry out an end-capping reaction at 210 °C and 0.5 MPa for 0.2 h to obtain polyethylene glycol succinate.

[0159] That is: In this comparative example, succinic acid is used as the raw material and a chain extension reaction is carried out.

[0160] Comparative Example 4

[0161] The difference between this comparative example and Example 1 is that the viscosity of the prepolymer obtained in S2 is 2 dL / g.

[0162] Test Example

[0163] ①. The poly(ethylene succinate) obtained in Examples 1-6 and Comparative Examples 1-4 was compared, and the results are shown in Tables 1 to 3.

[0164] A. The number-average molecular weight and weight-average molecular weight were measured by gel permeation chromatography, and the terminal carboxyl group content was measured by the back titration method of dissolving the sample for acid-base neutralization titration.

[0165] B. The drawing speed strength was measured with reference to 《ISO 527》, the flexural modulus was measured with reference to 《ISO 178》, and the elongation at break was measured with reference to 《ISO 527》.

[0166] C. Aging performance test: Since the essence of the hydrolysis aging of poly(ethylene succinate) is mainly the hydrolysis and cleavage of the poly(ethylene succinate) molecular chain with the moisture in the air, resulting in a decrease in molecular weight and a decrease in the mechanical properties of the material macroscopically. Therefore, the poly(ethylene succinate) slices were immersed in pure water, and the hydrolysis resistance of poly(ethylene succinate) could be measured by testing the decrease rate of the molecular weight of the sample with the continuous extension of the full hydrolysis reaction time (the melt index can characterize the molecular weight to a certain extent, and the increase rate of the melt index of the sample with the continuous extension of the full hydrolysis reaction time can also be tested).

[0167] The hydrolysis aging test method is as follows: Weigh 50 g of the finished poly(ethylene succinate) particles in a conical flask, add 100 g of deionized water to it, seal it with plastic wrap, and place it in an oven at 70 °C for 24 h and 48 h. Take 25 g of the particles, wash them with deionized water, and then dry them in an oven at 70 °C for 2-4 h, and measure the melt index after drying. The melt index was measured with reference to 《ISO 1133》.

[0168] Hydrolysis rate = (melt index after sample hydrolysis - melt index before sample hydrolysis) / melt index before sample hydrolysis. Under the same conditions and the same hydrolysis reaction time, the higher the hydrolysis melt index increase rate, the relatively weaker the hydrolysis resistance.

[0169] Table 1 Comparison results of poly(ethylene succinate)

[0170]

[0171] Table 2 Comparison results of poly(ethylene succinate) (continued)

[0172]

[0173]

[0174] Table 3 Comparison results of poly(ethylene succinate) (continued)

[0175] 24h hydrolysis rate (%) 48h hydrolysis rate (%) Natural aging time (days) Example 1 83 157 240 Example 2 173 344 160 Example 3 148 291 160 Example 4 105 279 220 Example 5 139 258 180 Example 6 163 307 160 Comparative Example 1 377 926 Originally brittle Comparative Example 2 184 386 15 Comparative Example 3 261 849 55 Comparative Example 4 115 223 180

[0176] As can be seen from Tables 1 to 3, the poly(ethylene succinate) synthesized in the examples of this application has a relatively high molecular weight, as well as mechanical properties, hydrolysis resistance and aging resistance.

[0177] In summary, in this application, by specifically using succinic anhydride or aliphatic alcohol diester of succinic acid as raw materials, the hydrolysis problem of the catalyst in the esterification reaction process is effectively reduced or avoided, and a large number of side reactions caused by the hydrolyzed catalyst in the polycondensation stage are prevented; the molecular weight of the product is effectively increased through a chain extension reaction, and by combining the end-blocking of the terminal carboxyl groups of the molecular chains after chain extension, poly(ethylene succinate) with excellent hydrolysis resistance and aging resistance and a relatively high molecular weight is obtained.

[0178] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polyethylene glycol succinate, characterized in that, The number-average molecular weight M of the polyethylene glycol succinate n is 50,000 g / mol - 850,000 g / mol, and the weight-average molecular weight M w is 100,000 g / mol - 1,500,000 g / mol, and the terminal carboxyl group content is not higher than 40 mol / t.

2. The polyethylene glycol succinate according to claim 1, characterized in that, The number-average molecular weight M of the polyethylene glycol succinate n is 50,000 g / mol - 830,000 g / mol; and / or, the weight-average molecular weight M of the polyethylene glycol succinate w is 830,000 g / mol - 1,300,000 g / mol; and / or, the terminal carboxyl group content of the polyethylene glycol succinate is 24 mol / t - 38 mol / t.

3. A method for synthesizing polyethylene glycol succinate as described in claim 1 or 2, characterized in that, It includes the following steps: Esterify any one of succinic anhydride and fatty alcohol diester of succinic acid with ethylene glycol. After the esterification is completed, carry out pre-polycondensation reaction to obtain a prepolymer of polyethylene glycol succinate; carry out chain extension reaction and end-capping reaction on the prepolymer.

4. The synthesis method according to claim 3, wherein The molar ratio of the ethylene glycol to the succinic anhydride is 1:1 to 100:

1.

5. The synthesis method according to claim 3, wherein The molar ratio of the ethylene glycol to the fatty alcohol diester of succinic acid is 1:1 to 100:1; Preferably, the fatty alcohol diester of succinic acid includes at least one of dimethyl succinate, diethyl succinate and diisopropyl succinate.

6. The synthesis method according to any one of claims 3-5, characterized in that, The esterification reaction includes at least one of the following characteristics: Characteristic 1: The temperature of the esterification reaction is 150°C - 250°C; Characteristic 2: In terms of absolute pressure, the pressure of the esterification reaction is 50 KPa - 100 KPa; Characteristic 3: The time of the esterification reaction is 1 h - 5 h; Characteristic 4: A catalyst is used during the esterification reaction process; Preferably, the catalyst includes an organic titanium compound; Preferably, the addition amount of the catalyst is 0.01% - 1% of the mass of the theoretically generated polyethylene glycol succinate.

7. The synthesis method according to any one of claims 3-5, characterized in that, The pre-polycondensation reaction includes at least one of the following characteristics: Characteristic 1: The temperature of the pre-polycondensation reaction is 150°C - 250°C; Characteristic 2: In terms of absolute pressure, the pressure of the pre-polycondensation reaction is 50 Pa - 10 Kpa; Characteristic 3: The time of the pre-polycondensation reaction is 1 h - 10 h; Preferably, the viscosity of the prepolymer obtained by the pre-polycondensation reaction does not exceed 1.6 dL / g; Preferably, the number-average molecular weight M of the prepolymer obtained by the pre-polycondensation reaction n is 25,000 g / mol - 40,000 g / mol, and the weight-average molecular weight is M w is 50,000 g / mol - 80,000 g / mol, and the terminal carboxyl group content is not higher than 40 mol / t.

8. The synthesis method according to any one of claims 3-5, characterized in that, The chain extension reaction includes at least one of the following characteristics: Characteristic 1: The temperature of the chain extension reaction is 150°C - 250°C; Characteristic 2: In terms of absolute pressure, the pressure of the chain extension reaction is 0.5 MPa - 5 MPa; Characteristic 3: The time of the chain extension reaction is 0.1 h - 1 h; Characteristic 4: The dosage of the chain extender used during the chain extension reaction process is 0.01% - 1% of the mass of the theoretically generated polyethylene glycol succinate; Preferably, the chain extender includes at least one of diisocyanate and epoxide; Preferably, the diisocyanate includes hexamethylene diisocyanate; Preferably, the epoxide includes a copolymer of styrene-methyl methacrylate-glycidyl methacrylate.

9. The synthesis method according to any one of claims 3-5, characterized in that, The end-capping reaction includes at least one of the following characteristics: Characteristic 1: The temperature of the end-capping reaction is 150°C - 250°C; Characteristic 2: In terms of absolute pressure, the pressure of the end-capping reaction is 0.1 MPa - 5 MPa; Characteristic 3: The time of the end-capping reaction is 0.1 h - 2 h; Characteristic 4: The dosage of the end-capping agent used during the end-capping reaction process is 0.01% - 1% of the mass of the theoretically generated polyethylene glycol succinate; Preferably, the end-capping agent includes a polyether with an epoxy functional group at the end and a molecular weight less than 5000 g / mol; Preferably, the end-capping agent includes at least one of polyglycol ether-based glycidyl ether and propylene oxide.

10. A packaging material, characterized in that, The raw materials for preparing the packaging material include the polyethylene glycol succinate according to any one of claims 1 - 3.

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