Crosslinked polyethylene glycol succinate as well as preparation method and application thereof

Abstract

The invention relates to cross-linked polyethylene glycol succinate as well as a preparation method and application thereof. The cross-linked polyethylene glycol succinate is prepared from succinic acid or dimethyl succinate, ethylene glycol and a functional branching agent through melt polycondensation under the action of a catalyst and a functional aid, the functional branching agent comprises one or more of the following substances: a hyperbranched polyhydroxy polymer, a polyamido compound and a hyperbranched polycarboxyl polymer. Compared with the prior art, by adding the functional branching agent, the prepared crosslinked polyethylene glycol succinate is higher in molecular weight, lower in melt index and adjustable in crosslinking degree, and has good heat resistance, mechanical property and biodegradability.

Description

Technical Field

[0001] The invention relates to the technical field of chemical modification, in particular to a cross-linked polyethylene glycol succinate and a preparation method and application thereof. Background Art

[0002] Aliphatic polyesters, as biodegradable plastics, have developed rapidly in recent years. Currently, the commercialized aliphatic polyesters mainly include polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoates (PHAs) and polybutylene succinate (PBS). Polyethylene succinate (PES), as a homologue of PBS, usually has a faster biodegradation rate than PBS and can be completely bio-based without consuming petroleum resources. Compared with PBS, it has a greater price advantage.

[0003] Whether from the perspective of raw material sources or PES performance and cost, PES is a type of highly promising environmentally friendly polyester with great application prospects. However, existing PES materials have problems such as poor melt thermal stability during molding, poor heat aging resistance of finished products, and / or mechanical strength that needs to be further enhanced, which limits their commercial application. Summary of the invention

[0004] The purpose of the present invention is to provide a cross-linked polyethylene succinate and a preparation method and application thereof in order to solve the above problems. The cross-linked polyethylene succinate is prepared by melt polycondensation of succinic acid or its dimethyl ester, ethylene glycol and a functional branching agent under the action of a catalyst and a functional auxiliary agent. The cross-linked polyethylene succinate has a higher molecular weight, a lower melt index, an adjustable degree of cross-linking, and good heat resistance, mechanical properties and biodegradability.

[0005] The purpose of the present invention is achieved through the following technical solutions:

[0006] The invention provides a method for preparing cross-linked polyethylene succinate. The cross-linked polyethylene succinate is prepared by melt polycondensation of succinic acid or dimethyl succinate, ethylene glycol and a functional branching agent in the presence of a catalyst and a functional auxiliary agent.

[0007] Furthermore, the cross-linked polyethylene glycol succinate has one or more of the following characteristics, and more preferably has all of the following characteristics:

[0008] (1) The weight average molecular weight of the cross-linked polyethylene succinate is between 100,000 and 200,000;

[0009] (2) The intrinsic viscosity of the cross-linked polyethylene glycol succinate is between 1.0 and 2.5 dL / g;

[0010] (3) The cross-linked polyethylene glycol succinate has a melt index of 1 to 50 g / 10 min under the test conditions of 190° C. and 2.16 kg;

[0011] (4) The tensile strength of the cross-linked polyethylene succinate is 20 to 60 MPa, and the elongation at break is 150% to 500%;

[0012] (5) The cross-linking degree of the cross-linked polyethylene succinate is between 50% and 99%.

[0013] Furthermore, the functional branching agent includes one or more of the following substances: a hyperbranched polyhydroxy polymer, a polyamine compound and a hyperbranched polycarboxyl polymer.

[0014] Furthermore, the hyperbranched polyhydroxy polymer includes one or more of a hyperbranched polyester polyol having a molecular weight of 500 to 10,000 or a hyperbranched polyether polyol having a molecular weight of 500 to 10,000.

[0015] Furthermore, the polyamine compound includes one or more of hexamethylenetetramine, tris(2-aminoethyl)amine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, low-molecular-weight polyethyleneimine with a molecular weight of 200 to 20,000, and amino-treated nanoparticles with a molecular weight of 200 to 20,000.

[0016] Furthermore, the polycarboxyl compound comprises a carboxyl-terminated hyperbranched polyamide having a molecular weight of 300 to 30,000.

[0017] As a preferred solution, the functional branching agent is a hyperbranched polyester polyol having a molecular weight of 500 to 10,000, and the hyperbranched polyester polyol is prepared by the following method:

[0018] (s1) adding equal moles of dibasic acid, diol and esterification catalyst into a reaction bottle, stirring with magnetic force at 60-80° C., and adding polyol in a molar ratio of 0.1% to 2% of the dibasic acid, wherein the amount of esterification catalyst is 0.01wt% to 0.2wt% of the dibasic acid;

[0019] (s2) Raise the temperature under a nitrogen atmosphere and react at 80-150° C. for 2-6 hours.

[0020] (s3) Reduce the pressure of the reaction system and continue the reaction within the range of 50 kPa to 50 Pa for 2 to 10 hours.

[0021] (s4) stopping the reaction, pouring out the product while hot, cooling it, crushing it into particles of 10 to 100 meshes, and drying it to obtain a hyperbranched polyester polyol having a molecular weight of 500 to 10,000.

[0022] More preferably, the molecular weight of the hyperbranched polyester polyol is 5,000-10,000.

[0023] Furthermore, the esterification catalyst can be a tin salt, a zinc salt, a titanium salt, a sulfur salt, tin oxide, zinc oxide, titanium oxide, sulfur oxide, or a combination thereof, preferably the same catalyst as that used to prepare cross-linked polyethylene succinate.

[0024] Furthermore, the dibasic acid may be one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like.

[0025] Furthermore, the diol may be one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol and the like.

[0026] Furthermore, the polyol can be selected from one or more of glycerol, pentaerythritol, dipentaerythritol, glycerol, xylitol, mannitol, sorbitol and the like.

[0027] As a preferred solution, the functional branching agent is an aminated nanoparticle with a molecular weight of 200 to 20,000. The nanoparticle can be selected from siloxane nanoparticles with a particle size of 10 to 500 nm. The aminated nanoparticle is prepared by the following method:

[0028] (s1) adding a silane coupling agent (e.g., silane coupling agent KH550, γ-aminopropyltriethoxysilane) and concentrated hydrochloric acid (37%) with a molar fraction of 0.05% to 0.5% (relative to the silane coupling agent) to a low-carbon alcohol solvent, and stirring with a magnetic stirrer;

[0029] (s2) the reaction system is reacted under continuous magnetic stirring at room temperature and pressure for 3 to 15 days, and then the excess solvent is removed by rotary evaporation until a flocculent to granular precipitate is formed, and the precipitate is filtered and dried at 50 to 70° C. (preferably 60° C.) to obtain white granules;

[0030] (s3) the obtained white particles are fully dissolved again in low-carbon alcohol, and then passed through a column filled with an anion exchange resin to obtain a nanoparticle mixed solution;

[0031] (s4) The obtained nanoparticle mixed solution is dried by rotary evaporation at 30-50° C. (preferably 40° C.) to obtain amino-treated siloxane nanoparticles with a molecular weight of 200-20,000.

[0032] More preferably, the molecular weight of the amination-treated siloxane nanoparticles is 5,000 to 20,000.

[0033] Furthermore, the low-carbon alcohol solvent is selected from one or more of methanol, ethanol, isopropanol, n-propanol and the like.

[0034] As a preferred solution, the functional branching agent is a carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000, and the carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000 is prepared by the following method:

[0035] (s1) under nitrogen atmosphere, a polar aprotic solvent (one or more of NMP, DMF, DMSO, DMAC), triphenyl phosphite in a molar ratio of 0.01% to 0.1% and pyridine are added to a reaction bottle and dissolved by magnetic stirring;

[0036] (s2) adding a polyacid / anhydride and a diamine into a reaction flask at a molar ratio of 0.5% to 5% excess carboxyl group, and mixing them uniformly at 60 to 90° C., wherein the molar ratio of the sum of the molar amounts of triphenyl phosphite and pyridine to the diamine is 0.01% to 0.1%, and the mass of the solvent accounts for 50% to 80% of the total;

[0037] (s3) heating the reaction system to 130-150° C. (preferably 140° C.) and continuing the reaction for 4-10 hours;

[0038] (s4) After the reaction is completed, the reaction solution is poured into water for precipitation, filtered and then dried to obtain a carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000.

[0039] More preferably, the molecular weight of the carboxyl-terminated hyperbranched polyamide is 5,000 to 30,000.

[0040] Furthermore, the polyacid / acid anhydride is selected from one or more of 2,2-hydroxymethylpropionic acid, 2,2-hydroxymethylbutyric acid, trimellitic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid, pyromellitic anhydride, trimesic acid and the like.

[0041] Furthermore, the diamine is selected from one or more of ethylenediamine, propylenediamine, hexamethylenediamine, p-phenylenediamine, o-phenylenediamine, m-phenylenediamine, and benzidine.

[0042] Furthermore, the molar ratio of succinic acid or dimethyl succinate: ethylene glycol: functional branching agent is 1: 1-2: 0.01%-5%.

[0043] Further, the catalyst includes but is not limited to one or more of tetrabutyl titanate, isopropyl titanate, stannous octoate, zinc acetate dihydrate, titanium glycolate, antimony glycolate, magnesium oxide, antimony trioxide, various metal organic frameworks, etc. The added amount of the catalyst is 0.01% to 0.5% of the amount of succinic acid or dimethyl succinate.

[0044] Furthermore, the functional additives include but are not limited to antioxidants, leveling agents, nucleating agents, flame retardants, and opening agents. The added amount of various functional additives is 0.01-10% of the amount of succinic acid or dimethyl succinate.

[0045] Furthermore, the antioxidant includes but is not limited to one or more of hindered phenols or phosphites, such as one or more of antioxidant 1010, antioxidant 168 or their compound products.

[0046] Furthermore, the leveling agent includes but is not limited to one or more of acrylic acid, silicone and fluorocarbon compounds, such as RF-7510 of Ruike Chemical, BYK-333 of Shanghai Pande, etc.

[0047] Furthermore, the nucleating agent includes but is not limited to one or more of various organic nanoparticles or inorganic nanoparticles, such as one or more of commercially available nano calcium carbonate, talcum powder, etc.

[0048] Furthermore, the flame retardant includes but is not limited to one or more of inorganic hydroxides and modified hydroxides thereof, phosphorus nitrogen flame retardants, silicone flame retardants, etc. For example, one or more of Doher-998 of Doher Chemical, APP flame retardant of Wanran Technology, etc.

[0049] Furthermore, the anti-blocking agent includes but is not limited to one or more of talc, diatomaceous earth, oleamide, erucamide and EBS (ethylene bis stearamide) derivatives, such as one or more of Lingwei Technology's K-80, K-35X, K-25, etc.

[0050] Furthermore, the preparation method comprises the following steps:

[0051] (S1) preheating the reactor at 80-120° C. for 20-60 min, introducing inert gas protection (for example, circulate / pass inert gas 2-6 times, evacuate to an absolute pressure of less than 200 Pa, and then inflate to normal pressure), and then adding succinic acid or dimethyl succinate, ethylene glycol, a functional branching agent, a functional auxiliary agent, and a catalyst into the reactor in a certain proportion;

[0052] (S2) raising the temperature of the reaction kettle and reacting at 150° C. to 190° C. for 2 to 8 hours until the volume or weight of the byproduct water / methanol reaches 60 to 90% of the complete reaction, and the esterification reaction is terminated;

[0053] (S3) evacuating the mixture at a rate of 0.1 to 10 kPa / min, raising the polycondensation reaction temperature to 210 to 260° C. and a vacuum degree of 500 to 30 Pa, and continuing the reaction for 2 to 16 hours;

[0054] (S4) When the viscosity of the polymer no longer increases, the reaction is terminated, the material is released, and pelletized to obtain cross-linked polyethylene succinate.

[0055] The present invention also provides an application of the polyethylene succinate as described above, which is applied to one or more of various degradable and recyclable material fields such as degradable film materials, disposable lunch boxes, disposable straws, disposable packing bags, disposable knives, disposable forks, disposable spoons, degradable logistics packaging, degradable tapes, degradable gift boxes, recyclable degradable injection molding products, and foaming materials.

[0056] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0057] The invention adopts succinic acid or its dimethyl ester (dimethyl succinate) and ethylene glycol to prepare cross-linked polyethylene succinate in the presence of a catalyst and a functional branching agent, wherein the functional branching agent is a polyamine compound or a hyperbranched oligomer. The cross-linked polyethylene succinate with a branched structure has a higher molecular weight, a lower melt index, an adjustable cross-linking degree, and good heat resistance, mechanical properties and biodegradability. DETAILED DESCRIPTION

[0058] The present invention is described in detail below in conjunction with specific embodiments, but is by no means intended to limit the present invention. Features such as preparation methods, materials, structures or composition ratios not explicitly described in this technical solution are considered to be common technical features disclosed in the prior art.

[0059] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0060] The relevant data in the present invention and its embodiments are tested according to the following standards or methods:

[0061] (1) The tensile strength and elongation at break were tested according to the test standard of GB / T 1040.2-2016, with a tensile speed of 50 mm / min and the average value of 5 groups of samples was taken;

[0062] (2) The weight average molecular weight is determined by gel permeation chromatography (GPC), and five standard molecular weights of methyl methacrylate with different molecular weights are used for molecular weight calibration. The specific process includes the following steps: dissolving the sample in a 5 mmol / L sodium trifluoroacetate hexafluoroisopropanol solution to prepare a 0.05-0.3 wt% (mass fraction) solution. The solution is then filtered through a polytetrafluoroethylene filter with a pore size of 0.4 μm. 20 μL of the filtered solution is added to the gel permeation chromatography (GPC) injector to determine the molecular weight of the sample;

[0063] (3) The cross-linking density was tested by nuclear magnetic resonance method;

[0064] (4) Intrinsic viscosity: Weigh about 0.125 g of the sample, dissolve it in 25 ml of hexafluoroisopropanol, and place it in a constant temperature water bath at 25°C. Use an Ubbelohde viscometer to measure the intrinsic viscosity (η). The average value is measured three times. The difference in the outflow time of each measurement does not exceed 0.2 seconds.

[0065] (5) Melt index (MFR) test: 1) Dry the copolymer in a vacuum drying oven at 105°C; 2) Set the test temperature of the test instrument to 190°C and preheat the instrument; 3) Load 4g of the dried copolymer into a barrel through a funnel, and insert a piston into the barrel to press the dried copolymer into a rod; 4) Keep the dried copolymer in the rod for 1 minute under the condition that a weight of 2.16kg is pressed on the top of the rod, and then cut a section every 30s to obtain a total of five sections; 5) Weigh the mass of each sample and calculate its MFR. MFR = 600W / t (g / 10min), where W is the average mass of each sample, and t is the cutting time interval of each section.

[0066] Comparative Example 1

[0067] This comparative example provides a method for preparing cross-linked polyethylene glycol succinate, wherein the functional branching agent used is pentaerythritol, and the method comprises the following steps:

[0068] The reactor was preheated at 100°C for 30 minutes, and nitrogen was circulated / exhausted 4 times. Succinic acid, ethylene glycol and pentaerythritol were added to the reactor in a molar ratio of 1:1.2:0.5%, and tetrabutyl titanate with a molar fraction of 0.1% (relative to succinic acid) and an antioxidant 1010 with a molar ratio of 0.5% to succinic acid were added. The temperature was raised to 190°C, and the reaction was continued for 5 hours until the amount of by-products (water) reached 80% of the complete reaction, and the esterification reaction was terminated. Then, the vacuum was evacuated at a rate of 6 kPa / min, and the polycondensation reaction temperature was increased, and the reaction was continued for 6 hours under the conditions of 230°C and a vacuum degree of 50 Pa, until the viscosity of the polymer no longer increased, the reaction was terminated, the material was discharged, and pelletized to obtain polyethylene succinate.

[0069] Embodiment 1:

[0070] This embodiment provides a method for preparing cross-linked polyethylene glycol succinate, wherein the functional branching agent used is a hyperbranched polyester polyol with a molecular weight of 500 to 10,000, comprising the following steps:

[0071] Preparation of hyperbranched polyester polyol: add equimolar succinic acid and ethylene glycol and 0.1wt% (relative to succinic acid) of stannous chloride into a reaction bottle, add pentaerythritol at a molar ratio of 0.5% to succinic acid under 70°C and magnetic stirring; gradually increase the temperature under a slightly positive nitrogen atmosphere, react at 110°C for 3h; gradually reduce the pressure of the reaction system, and continue to react at 1kPa for 2h; after the reaction is completed, pour out the product while hot, cool it, crush it into 50 mesh particles and dry it to obtain hyperbranched poly(ethylene succinate). The molecular weight of the hyperbranched poly(ethylene succinate) is measured to be 8600g / mol.

[0072] Preparation of cross-linked polyethylene succinate: The preparation method is the same as that of comparative example 1, except that the molar fraction of 0.5% (relative to succinic acid) of pentaerythritol is replaced with the molar fraction of 0.5% (relative to succinic acid) of the above-mentioned hyperbranched polyethylene succinate to prepare cross-linked polyethylene succinate.

[0073] Example 2

[0074] This embodiment provides a method for preparing cross-linked polyethylene succinate. The preparation method is the same as that of Example 1, except that the molar addition amount of hyperbranched polyethylene succinate is changed from 0.5% to 1% (relative to succinic acid) to prepare cross-linked polyethylene succinate.

[0075] Example 3

[0076] This embodiment provides a method for preparing cross-linked polyethylene succinate. The preparation method is the same as that of Example 1, except that the molar addition amount of hyperbranched polyethylene succinate is changed from 0.5% to 2% (relative to succinic acid) to prepare cross-linked polyethylene succinate.

[0077] Example 4

[0078] This embodiment provides a method for preparing cross-linked polyethylene glycol succinate, wherein the functional branching agent used is a carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000, comprising the following steps:

[0079] Preparation of carboxyl-terminated hyperbranched polyamide: Under nitrogen atmosphere, add appropriate amount of polar non-protonic solvent DMSO, triphenyl phosphite and pyridine in a molar ratio of 1:1 (the molar ratio of the sum of the molar amounts of triphenyl phosphite and pyridine to hexamethylenediamine in the subsequent step is 0.05%) to a reaction bottle, stir magnetically to dissolve; add trimellitic anhydride and hexamethylenediamine to the reaction bottle in a molar ratio of 2% excess carboxyl, mix evenly at 80°C, DMSO solvent accounts for 60% of the mass in the system; heat the reaction system to 140°C, and continue the reaction for 6 hours; after the reaction is completed, pour the reaction solution into water for precipitation, filter and dry, and a carboxyl-terminated hyperbranched polyamide can be obtained. The molecular weight of the hyperbranched polyamide is measured to be 12000g / mol.

[0080] Preparation of cross-linked polyethylene succinate: The preparation method is the same as that of Comparative Example 1, except that the molar fraction of 0.5% (relative to succinic acid) of pentaerythritol is replaced by the molar fraction of 1% (relative to succinic acid) of the above-mentioned hyperbranched polyamide to prepare cross-linked polyethylene succinate.

[0081] Example 5

[0082] This embodiment provides a method for preparing cross-linked polyethylene succinate. The preparation method is the same as that of Example 4, except that the molar addition amount of the hyperbranched polyamide is changed from 1% to 2% (relative to succinic acid) to prepare the cross-linked polyethylene succinate.

[0083] Example 6

[0084] This embodiment provides a method for preparing cross-linked polyethylene succinate. The preparation method is the same as that of Example 4, except that the amount of hyperbranched polyamide added is changed from 1% to 4% (relative to succinic acid) to prepare cross-linked polyethylene succinate.

[0085] Example 7

[0086] This embodiment provides a method for preparing cross-linked polyethylene glycol succinate, wherein the functional branches used are amino-treated nanoparticles with a molecular weight of 200 to 20,000. The preparation method comprises the following steps:

[0087] Silane coupling agent KH550 and 0.1% mole fraction (relative to silane coupling agent KH550) of concentrated hydrochloric acid (37%) are added to methanol and magnetically stirred; the reaction system is continuously magnetically stirred for 10 days at room temperature and pressure, and the excess solvent is removed by rotary evaporation until flocculent to granular precipitates appear, which are filtered and dried at 60°C; the obtained white particles are fully dissolved in methanol again, and then passed through a column filled with anion exchange resin to obtain a nanoparticle solution; the obtained nanoparticle solution is dried by rotary evaporation at 40°C to obtain amino-treated nanoparticles with a molecular weight of 15000 g / mol.

[0088] Preparation of cross-linked polyethylene succinate: The preparation method is the same as that of comparative example 1, except that the molar fraction of 0.5% (relative to succinic acid) of pentaerythritol is replaced with the molar fraction of 1% (relative to succinic acid) of the above-mentioned amino-treated nanoparticles to prepare cross-linked polyethylene succinate.

[0089] Example 8

[0090] This embodiment provides a method for preparing cross-linked polyethylene glycol succinate. The preparation method is the same as that of Example 7, except that the molar addition amount of the amino-treated nanoparticles is changed from 1% to 2% (relative to succinic acid) to prepare cross-linked polyethylene glycol succinate.

[0091] Comparative Example 2

[0092] This comparative example provides a method for preparing polyethylene succinate, wherein the functional branching agent used is polyethylene succinate, and the preparation method of the functional branching agent polyethylene succinate is the same as that of Example 1, except that, in the process of preparing the functional branching agent polyethylene succinate, pentaerythritol is not added, and succinic acid and ethylene glycol are added to the reaction bottle at a molar ratio of 2% excess hydroxyl. The molecular weight of the prepared polyethylene succinate is measured to be 2600 g / mol.

[0093] The preparation method of cross-linked polyethylene succinate is the same as that of Example 1, except that the hyperbranched polyethylene succinate is replaced with the above-mentioned polyethylene succinate to prepare the cross-linked polyethylene succinate.

[0094] Comparative Example 3

[0095] This comparative example provides a method for preparing cross-linked polyethylene succinate. The preparation method is the same as that of Example 1, except that the molar addition amount of hyperbranched polyethylene succinate is changed from 0.5% to 10% (relative to succinic acid) to prepare cross-linked polyethylene succinate.

[0096] The performance tests were performed on the samples obtained in Examples 1 to 8 and Comparative Examples 1 to 3. The obtained performance test results are shown in Table 1.

[0097] Table 1 Performance test results of various embodiments and comparative examples

[0098]

[0099] As shown in Table 1, Example 1 is compared with Comparative Example 1. It can be seen that the use of hyperbranched polyester polyol as a functional branching agent can effectively improve the crosslinking degree of crosslinked polyethylene succinate compared to the commonly used branching agent, pentaerythritol, so that its weight average molecular weight, intrinsic viscosity, tensile strength and elongation at break are significantly improved; the use of carboxyl-terminated hyperbranched polyamide or amino-treated nanoparticles as a functional branching agent, compared with the same amount of hyperbranched polyester polyol, the crosslinking degree of the obtained crosslinked polyethylene succinate is equivalent, and its weight average molecular weight, intrinsic viscosity, tensile strength and elongation at break are also equivalent or slightly improved. Further, compared to the commonly used branching agent, pentaerythritol, the melt index of the crosslinked polyethylene succinate obtained in the present application example is between 1 and 15 g / 10 min (190° C., 2.16 kg), and has good hot melt stability.

[0100] Example 1 is compared with Comparative Example 2. In the process of preparing polyester polyol, no polyol is added, and only succinic acid and ethylene glycol are used for esterification reaction. The obtained polyester polyol has a linear structure. When linear polyester polyol is used as a functional branching agent, the obtained cross-linked poly(ethylene succinate) has an extremely low degree of crosslinking, which cannot be detected in the melt index test due to excessive outflow, and the tensile strength and elongation at break are low, and the product is brittle.

[0101] Example 1 is compared with Comparative Example 3. When the molar fraction of the functional branching agent (relative to succinic acid) is 10% (greater than 5%), the obtained cross-linked polyethylene succinate is insoluble in 5 mmol / L sodium trifluoroacetate hexafluoroisopropanol solution or hexafluoroisopropanol, and the cross-linking is excessive.

[0102] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing cross-linked polyethylene glycol succinate, characterized in that: The cross-linked polyethylene succinate is prepared by melt polycondensation of succinic acid or dimethyl succinate, ethylene glycol and a functional branching agent in the presence of a catalyst and a functional additive; The functional branching agent includes one or more of the following substances: a hyperbranched polyhydroxy polymer, a polyamine compound and a hyperbranched polycarboxyl polymer.

2. The method for preparing cross-linked polyethylene glycol succinate according to claim 1, characterized in that: The hyperbranched polyhydroxy polymer includes one or more of a hyperbranched polyester polyol having a molecular weight of 500 to 10,000 or a hyperbranched polyether polyol having a molecular weight of 500 to 10,000; The polyamine compound includes one or more of hexamethylenetetramine, tris(2-aminoethyl)amine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, oligoethyleneimine with a molecular weight of 200 to 20,000, and aminated nanoparticles with a molecular weight of 200 to 20,000; The hyperbranched polycarboxyl polymer comprises a carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000.

3. The method for preparing cross-linked polyethylene glycol succinate according to claim 2, characterized in that: The functional branching agent is a hyperbranched polyester polyol with a molecular weight of 500 to 10,000. The preparation of the hyperbranched polyester polyol with a molecular weight of 500 to 10,000 comprises the following steps: (s1) stirring an equimolar amount of a dibasic acid and a diol, and an esterification catalyst at 60 to 80° C., and simultaneously adding a polyol in a molar ratio of 0.1% to 2% of the dibasic acid; (s2) heating under a nitrogen atmosphere and reacting at 80-150° C. for 2-6 hours; (s3) reducing the pressure of the reaction system and continuing the reaction within the range of 50 kPa to 50 Pa for 2 to 10 hours; (s4) stopping the reaction, and after the product is cooled, crushing the product into particles of 10 to 100 meshes, and drying to obtain a hyperbranched polyester polyol having a molecular weight of 500 to 10,000.

4. The method for preparing cross-linked polyethylene glycol succinate according to claim 2, characterized in that: The functional branching agent is an aminated nanoparticle with a molecular weight of 200 to 20,000, the nanoparticle is selected from siloxane nanoparticles, and the particle size is 10 to 500 nm. The preparation of the aminated nanoparticle includes the following steps: (s1) adding a silane coupling agent and concentrated hydrochloric acid having a molar fraction of 0.05% to 0.5% relative to the silane coupling agent to a low-carbon alcohol solvent, and stirring the mixture with a magnetic stirrer; (s2) the reaction system is reacted under continuous magnetic stirring at room temperature and pressure for 3 to 15 days, and then the excess solvent is removed by rotary evaporation until a precipitate is formed, and the precipitate is filtered and dried at 50 to 70° C. to obtain white particles; (s3) the obtained white particles are redissolved in low-carbon alcohol, and then passed through a column filled with an anion exchange resin to obtain a nanoparticle mixed solution; (s4) The obtained nanoparticle mixed solution is dried by rotary evaporation at 30-50° C. to obtain amino-treated siloxane nanoparticles with a molecular weight of 200-20,000.

5. The method for preparing cross-linked polyethylene glycol succinate according to claim 2, characterized in that: The functional branching agent is a carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000. The preparation of the carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000 comprises the following steps: (s1) under a nitrogen atmosphere, uniformly mixing a polar aprotic solvent, triphenyl phosphite and pyridine to obtain a mixed solution, wherein the molar ratio of triphenyl phosphite to pyridine is 1:1; (s2) mixing the polyacid / anhydride and the diamine with the mixed solution of step (s1) at a molar ratio of 0.5% to 5% excess carboxyl group, and mixing them uniformly at 60 to 90° C., wherein the molar ratio of the sum of the molar amounts of triphenyl phosphite and pyridine to the diamine is 0.01% to 0.1%; (s3) raising the temperature of the reaction system to 130-150° C. and continuing the reaction for 4-10 hours; (s4) After the reaction is completed, the reaction solution is poured into water for precipitation, filtered and then dried to obtain a carboxyl-terminated hyperbranched polyamide with a molecular weight of 300 to 30,000.

6. The method for preparing cross-linked polyethylene succinate according to claim 1, characterized in that: The molar ratio of succinic acid or dimethyl succinate: ethylene glycol: functional branching agent is 1: 1-2: 0.01%-5%.

7. The method for preparing cross-linked polyethylene glycol succinate according to claim 1, characterized in that: The functional additives include one or more of antioxidants, leveling agents, nucleating agents, flame retardants and opening agents. The added amount of each functional additive is 0.01-10% of the amount of succinic acid or dimethyl succinate.

8. The method for preparing cross-linked polyethylene succinate according to any one of claims 1 to 7, characterized in that: The preparation method comprises: (S1) preheating the reactor at 80-120° C. for 20-60 min, introducing inert gas protection, and then adding succinic acid or dimethyl succinate, ethylene glycol, functional branching agent, functional auxiliary agent, and catalyst into the reactor in a certain proportion; (S2) raising the temperature of the reaction kettle to react at 150° C. to 190° C. for 2 to 8 hours to terminate the esterification reaction; (S3) evacuating the mixture at a rate of 0.1 to 10 kPa / min, raising the polycondensation reaction temperature to 210 to 260° C. and a vacuum degree of 500 to 30 Pa, and continuing the reaction for 2 to 16 hours; (S4) ending the reaction, releasing the material, and pelletizing to obtain cross-linked polyethylene succinate.

9. A cross-linked polyethylene glycol succinate, characterized in that: The cross-linked polyethylene glycol succinate is prepared by the preparation method according to any one of claims 1 to 8.

10. A use of the cross-linked polyethylene succinate prepared by the preparation method according to any one of claims 1 to 8 or the cross-linked polyethylene succinate according to claim 9, characterized in that: The cross-linked polyethylene glycol succinate is applied in the field of degradable and recyclable materials.

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