Polycarbonate diol containing bio-based structure, preparation method and application

Abstract

The present invention provides a polycarbonate diol containing a bio-based structure, a preparation method and an application, and belongs to the field of polycarbonate diols. The polycarbonate diol containing a bio-based structure is characterized in that it adopts bio-based 1,3-propylene glycol, bio-based 1,4-butylene glycol, and dimethyl carbonate as raw materials, and is obtained by ester exchange reaction and polycondensation reaction. The preparation method of the polycarbonate diol containing a bio-based structure of the present invention, prepares a polycarbonate diol of a block copolymer bio-based structure, can effectively regulate the number average molecular weight of the prepared polycarbonate diol, and the distribution range of the number average molecular weight is narrow; at the same time, the biocarbon content of the polycarbonate diol is increased, the biocompatibility of the polycarbonate diol is increased, and the compatibility of the polycarbonate diol with cellulose acetate is increased, and the plasticizing effect of the polycarbonate diol on cellulose acetate is increased.

Description

Technical Field

[0001] The invention relates to the field of polycarbonate diols, and in particular to a polycarbonate diol containing a bio-based structure, a preparation method and an application thereof. Background Art

[0002] With the development of material technology and the times, polyether diols and conventional polyester diols are gradually unable to meet the performance requirements of the industry; polycarbonate polyurethanes have the advantages of both polyether and polyester polyurethanes, and have excellent hydrolysis resistance and mechanical properties. Therefore, research on polycarbonate diols (PCDL) is increasing. Polycarbonate polyurethanes prepared using polycarbonate diols are highly valued by the polyurethane industry.

[0003] Polycarbonate polyurethane synthesized with polycarbonate diol as the soft segment has the advantages of both polyether and polyester polyurethanes, as well as excellent wear resistance, weather resistance, oil resistance and mildew resistance. It can be widely used in the fields of shoemaking, plastic running tracks and building sealing. In addition, due to its good biocompatibility, it can also be used as medical equipment and artificial organs in the medical and health fields.

[0004] The existing synthesis methods of polycarbonate diols mainly include phosgene method, cyclic carbonate ring-opening polymerization method, carbon dioxide-epoxide regulation copolymerization method, and ester exchange polycondensation method. Among them, the production risk of the phosgene method is relatively high, the product yield is low, and it has been gradually eliminated. The production cost of the cyclic carbonate ring-opening polymerization method is high, and the reaction conditions are demanding, which cannot be applied to the requirements of industrial large-scale production. The production performance of the carbon dioxide-epoxide regulation copolymerization method is unstable, and the post-processing is difficult, and it also cannot meet the requirements of industrial large-scale production. The ester exchange polycondensation method usually uses dialkyl carbonate and small molecule aliphatic diols to prepare polycarbonate diols through ester exchange polycondensation. It can avoid the use of highly toxic phosgene, and the raw materials are relatively cheap and easy to obtain, and the reaction conditions are mild. It is the current mainstream production process of polycarbonate diols.

[0005] However, the existing method for preparing polycarbonate diol by transesterification polycondensation method makes it difficult to control the number average molecular weight of the prepared polycarbonate diol, and the distribution of the number average molecular weight is difficult to control. At the same time, the biocarbon content of the polycarbonate diol prepared by the existing process is low, and the biocompatibility needs to be further improved; further, the inventors have also found through research that the low biocarbon content of the polycarbonate diol also leads to its poor compatibility with cellulose acetate, and the plasticizing effect of the polycarbonate diol on cellulose acetate needs to be further improved. Summary of the invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a polycarbonate diol containing a bio-based structure, a preparation method and an application, which can effectively control the number average molecular weight of the prepared polycarbonate diol, and the distribution range of the number average molecular weight is narrow; at the same time, the biocarbon content of the polycarbonate diol is increased, the biocompatibility of the polycarbonate diol is increased, and the compatibility of the polycarbonate diol with cellulose acetate is increased, and the plasticizing effect of the polycarbonate diol on cellulose acetate is improved.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a polycarbonate diol containing a bio-based structure, which uses bio-based 1,3-propylene glycol, bio-based 1,4-butanediol and dimethyl carbonate as raw materials, performs an ester exchange reaction, and then performs a polycondensation reaction to obtain the polycarbonate diol containing a bio-based structure.

[0009] In the polycarbonate diol containing a bio-based structure, the bio-based structure comes from bio-based 1,3-propylene glycol and bio-based 1,4-butanediol.

[0010] The method for preparing the polycarbonate diol containing a bio-based structure comprises the following steps: an ester exchange step and a polycondensation step.

[0011] The method of the ester exchange step is to add the bio-based diol into the reaction kettle, heat it to 130-170° C., add the composite regulator, and then start to drop dimethyl carbonate; control the drop time of dimethyl carbonate to be 10-15 hours, and after the drop addition of dimethyl carbonate is completed, keep warm and stir for 4-5 hours, and then distill to remove unreacted dimethyl carbonate and by-product impurities to obtain a homogeneous prepolymer solution.

[0012] Preferably, the transesterification reaction temperature is 140-150°C.

[0013] Further, the molar ratio of bio-based diol to dimethyl carbonate is 1:1-1.03;

[0014] The bio-based diols are bio-based 1,3-propylene glycol and bio-based 1,4-butanediol, and the molar ratio of the bio-based 1,3-propylene glycol to the bio-based 1,4-butanediol is 7-7.5:2.5-3.

[0015] Further, the addition amount of the composite regulator is 0.4-0.5% of the weight of dimethyl carbonate;

[0016] The composite regulator is prepared by the following steps: preparing a catalytic carrier and grafting and composite;

[0017] The method for preparing the catalytic carrier comprises the following steps: adding calcium chloride, aluminum chloride and magnesium chloride into an ethanol solution under stirring conditions, stirring for 20-30 minutes, adding polyethylene oxide, stirring evenly, cooling to 0-2°C, and dripping propylene oxide while keeping the temperature; controlling the dripping time of propylene oxide to be 5-10 minutes, and continuing to stir for 10-20 minutes after the dripping of propylene oxide is completed; placing the solution in a 40-45°C temperature environment after ultrasonic degassing, standing for 22-24 hours to obtain a gel; placing the gel in a constant temperature drying oven, drying at 60-65°C for 72-78 hours, transferring the gel into a calcining furnace, heating the solution to 900-950°C at a heating rate of 1.5-1.8°C / min, keeping the temperature for calcining for 2-3 hours, cooling naturally, and crushing and grinding the solution to a particle size of 50-60 μm to obtain the catalytic carrier.

[0018] Furthermore, in the preparation of the catalytic carrier, the volume concentration of the ethanol solution is 50-55%.

[0019] The mass ratio of calcium chloride, aluminum chloride, magnesium chloride, ethanol solution, polyethylene oxide and propylene oxide is 4-4.3:7.8-8:1-1.2:22-25:0.3-0.35:5-5.3.

[0020] The grafting composite method comprises the following steps: adding a catalytic carrier into 17-19 times the weight of toluene, uniformly dispersing the catalyst carrier through ultrasonication, adding S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate through stirring, heating the catalyst carrier to 95-100°C at a heating rate of 0.8-1.2°C / min, keeping the temperature under reflux and stirring for 10-12h, filtering out solids, and drying the solids to obtain a composite regulator.

[0021] Furthermore, in the graft composite, the weight ratio of the catalyst carrier to S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is 10:5-5.5.

[0022] The polycondensation step comprises the following steps: starting a vacuum pump, controlling the vacuum degree of a reaction kettle containing a homogeneous prepolymer solution to 700-800 Pa, heating the reaction kettle to 170-230° C. at a heating rate of 1.2-1.6° C. / min, maintaining the polycondensation reaction for 3-5 hours, filtering out and recovering solid matter, and obtaining a bio-based structure-containing polycarbonate diol with a predetermined molecular weight and molecular weight distribution.

[0023] Preferably, the polycondensation reaction temperature is 190-210°C.

[0024] A polycarbonate diol containing a bio-based structure is prepared by the above-mentioned preparation method; the bio-based structure of the polycarbonate diol containing a bio-based structure includes: HO-(CH2)3-OH, HO-(CH2)4-OH;

[0025] The biocarbon content of the polycarbonate diol containing a bio-based structure is 75-80 wt %.

[0026] A use of the aforementioned polycarbonate diol containing a bio-based structure in a plasticizer for cellulose acetate.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The polycarbonate diol containing a bio-based structure of the present invention uses bio-based 1,3-propylene glycol, bio-based 1,4-butanediol, and dimethyl carbonate in specific dosage ratios as main raw materials, and in the presence of a composite regulator, controls the specific feeding time of dimethyl carbonate and the insulation reaction time after the addition of dimethyl carbonate to carry out an ester exchange reaction to obtain a homogeneous prepolymer solution; at the same time, in the preparation of the composite regulator, calcium chloride, aluminum chloride, magnesium chloride, polyethylene oxide, and propylene oxide are used to prepare a magnesium-doped calcium aluminum hydrotalcite (i.e., a catalytic carrier) having ester exchange catalytic activity; then, on the basis of the catalytic carrier, the catalytic carrier is subjected to high-temperature calcination activation and magnesium doping treatment during the preparation process to further increase the surface active sites of the catalytic carrier, and then in the grafting composite step, ensure that S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is effectively grafted to the magnesium-doped calcium aluminum hydrotalcite surface, to prepare a composite regulator; in the ester exchange reaction stage, the composite regulator controls the progress of the ester exchange reaction through the catalytic effect of the catalytic carrier (magnesium-doped calcium aluminum hydrotalcite) on the ester exchange reaction; then, under the action of the composite regulator, the homogeneous prepolymer solution continues to carry out the polycondensation step through the regulating effect of the S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate grafted on the surface of the catalytic carrier on the polymerization molecular weight, to prepare a polycarbonate diol containing a bio-based structure with a predetermined molecular weight and a narrow molecular weight distribution; the aforementioned technical means cooperate and work synergistically with each other, and can effectively regulate the number average molecular weight of the prepared polycarbonate diol, and the distribution range of the number average molecular weight is narrow; at the same time, the biocarbon content of the polycarbonate diol is increased, the biocompatibility of the polycarbonate diol is increased, and the compatibility of the polycarbonate diol with cellulose acetate is increased, and the plasticizing effect of the polycarbonate diol on cellulose acetate is increased.

[0029] (2) The bio-based structure-containing polycarbonate diol of the present invention has a biocarbon content of up to 80.1 wt%, a number average molecular weight of 800, a viscosity of 337 cp, and a number average molecular weight distribution coefficient (PDI) of 1.2-1.4; the polycarbonate diol has a high biocarbon content and a narrow molecular weight distribution.

[0030] (3) The polycarbonate diol containing a bio-based structure of the present invention is synthesized using bio-based raw materials of bio-based 1,3-propylene glycol and bio-based 1,4-butanediol, has good biocompatibility, and can be effectively used in the preparation of bio-based materials; the polycarbonate diol containing a bio-based structure can be used in a more environmentally friendly manner in combination with bio-based isocyanate to prepare downstream bio-based polyurethane materials.

[0031] (4) The polycarbonate diol containing a bio-based structure of the present invention is prepared from bio-based raw materials of bio-based 1,3-propylene glycol and bio-based 1,4-butanediol to obtain a non-crystalline polycarbonate diol at room temperature, which effectively improves the compatibility of the polycarbonate diol with cellulose acetate and improves the plasticizing effect of the polycarbonate diol on cellulose acetate.

[0032] (5) The high biocarbon content of the polycarbonate diol containing a bio-based structure of the present invention further expands the application of polycarbonate diol in the fields of chemical industry, new materials, medicine, etc. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described.

[0034] Example 1

[0035] This embodiment provides a method for preparing a polycarbonate diol containing a bio-based structure, specifically:

[0036] 1. Transesterification step

[0037] Add the bio-based diol into the reactor, heat it to 145°C, add the composite regulator, and then start to drop dimethyl carbonate; the dropping time of dimethyl carbonate is controlled to be 12 hours. After the dropping of dimethyl carbonate is completed, keep warm and stir for 4.5 hours, then distill to remove the unreacted dimethyl carbonate and by-product impurities to obtain a homogeneous prepolymer solution.

[0038] Among them, the molar ratio of bio-based diol to dimethyl carbonate is 1:1.02.

[0039] The bio-based diols are bio-based 1,3-propylene glycol and bio-based 1,4-butanediol, and the molar ratio of the bio-based 1,3-propylene glycol to the bio-based 1,4-butanediol is 7:3.

[0040] The added amount of the composite regulator is 0.45% of the weight of dimethyl carbonate.

[0041] The preparation method of the composite regulator is:

[0042] 1) Preparation of catalytic carrier

[0043] Under stirring conditions, calcium chloride, aluminum chloride and magnesium chloride are added to an ethanol solution. After stirring for 25 minutes, polyethylene oxide is added. After stirring evenly, the temperature is lowered to 0°C, and propylene oxide is added while keeping warm; the addition time of propylene oxide is controlled to be 7 minutes. After the addition of propylene oxide is completed, stirring is continued for 15 minutes; after ultrasonic degassing, the solution is placed in a 42°C temperature environment and allowed to stand for 23 hours to obtain a gel; the gel is placed in a constant temperature drying oven, dried at 62°C for 76 hours, and then transferred to a calcining furnace, heated to 930°C at a heating rate of 1.6°C / min, kept warm and calcined for 2.5 hours, cooled naturally, and crushed to a particle size of 55μm to obtain a catalytic carrier.

[0044] Among them, the volume concentration of the ethanol solution is 52%.

[0045] The mass ratio of calcium chloride, aluminum chloride, magnesium chloride, ethanol solution, polyethylene oxide and propylene oxide is 4.2:7.9:1.1:23.5:0.33:5.2.

[0046] 2) Grafting

[0047] The catalyst carrier is put into 18 times the weight of toluene, and after ultrasonic dispersion, S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is added with stirring, and heated to 98°C at a heating rate of 1°C / min. After reflux stirring for 11 hours, the solid is filtered out and dried to obtain a composite regulator.

[0048] Wherein, the weight ratio of the catalytic carrier to S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is 10:5.2.

[0049] 2. Polycondensation step

[0050] Turn on the vacuum pump, control the vacuum degree of the reactor containing the homogeneous prepolymer solution to 750 Pa, heat to 200°C at a heating rate of 1.4°C / min, keep the temperature for 4 hours for polycondensation reaction, filter out and recover the solid matter, and obtain a bio-based structure-containing polycarbonate diol with a predetermined molecular weight and molecular weight distribution.

[0051] The bio-based structure of the polycarbonate diol containing a bio-based structure includes: HO-(CH2)3-OH, HO-(CH2)4-OH; the biocarbon content of the polycarbonate diol containing a bio-based structure is 80.1wt%, the number average molecular weight is 800, the viscosity is 337cp, and the number average molecular weight distribution coefficient (PDI) is 1.2.

[0052] This embodiment also provides a polycarbonate diol containing a bio-based structure, which is prepared by the above-mentioned preparation method of the polycarbonate diol containing a bio-based structure; the specific structure of the polycarbonate diol containing a bio-based structure is shown as follows:

[0053]

[0054] This embodiment also provides the use of the aforementioned polycarbonate diol containing a bio-based structure in a plasticizer for cellulose acetate.

[0055] Example 2

[0056] This embodiment provides a method for preparing a polycarbonate diol containing a bio-based structure, specifically:

[0057] 1. Transesterification step

[0058] Add the bio-based diol into the reactor, heat it to 140°C, add the composite regulator, and then start to drop dimethyl carbonate; the dropping time of dimethyl carbonate is controlled to be 10 hours. After the dropping of dimethyl carbonate is completed, keep warm and stir for 4 hours, then distill to remove the unreacted dimethyl carbonate and by-product impurities to obtain a homogeneous prepolymer solution.

[0059] The molar ratio of bio-based diol to dimethyl carbonate is 1:1.

[0060] The bio-based diols are bio-based 1,3-propylene glycol and bio-based 1,4-butanediol, and the molar ratio of bio-based 1,3-propylene glycol to bio-based 1,4-butanediol is 7.2:2.8.

[0061] The added amount of the composite regulator is 0.4% of the weight of dimethyl carbonate.

[0062] The preparation method of the composite regulator is:

[0063] 1) Preparation of catalytic carrier

[0064] Under stirring conditions, calcium chloride, aluminum chloride and magnesium chloride are added to an ethanol solution, and after stirring for 20 minutes, polyethylene oxide is continuously added, and after stirring evenly, the temperature is lowered to 1°C, and propylene oxide is dripped in while being kept warm; the dripping time of propylene oxide is controlled to be 5 minutes, and after the dripping of propylene oxide is completed, stirring is continued for 10 minutes; after ultrasonic degassing, the solution is placed in a 40°C temperature environment and allowed to stand for 22 hours to obtain a gel; the gel is placed in a constant temperature drying oven, dried at 60°C for 72 hours, and then transferred to a calcining furnace, heated to 900°C at a heating rate of 1.5°C / min, kept warm and calcined for 2 hours, naturally cooled, crushed and ground to a particle size of 50μm to obtain a catalytic carrier.

[0065] Wherein, the volume concentration of ethanol solution is 50%.

[0066] The mass ratio of calcium chloride, aluminum chloride, magnesium chloride, ethanol solution, polyethylene oxide and propylene oxide is 4:7.8:1:22:0.3:5.

[0067] 2) Grafting

[0068] The catalyst carrier is put into 17 times the weight of toluene, and after ultrasonic dispersion, S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is added with stirring, and heated to 95°C at a heating rate of 0.8°C / min. After reflux stirring for 10 hours, the solid is filtered out and dried to obtain a composite regulator.

[0069] Wherein, the weight ratio of the catalytic carrier to S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is 10:5.

[0070] 2. Polycondensation step

[0071] Turn on the vacuum pump, control the vacuum degree of the reactor containing the homogeneous prepolymer solution to 700 Pa, heat to 190°C at a heating rate of 1.2°C / min, keep the temperature for 3 hours for polycondensation reaction, filter out and recover the solid matter, and obtain a bio-based structure-containing polycarbonate diol with a predetermined molecular weight and molecular weight distribution.

[0072] The bio-based structure of the polycarbonate diol containing a bio-based structure includes: HO-(CH2)3-OH, HO-(CH2)4-OH; the biocarbon content of the polycarbonate diol containing a bio-based structure is 78.7wt%, the number average molecular weight is 820, the viscosity is 341cp, and the number average molecular weight distribution coefficient (PDI) is 1.3.

[0073] This embodiment also provides a polycarbonate diol containing a bio-based structure, which is prepared by the aforementioned method for preparing the polycarbonate diol containing a bio-based structure.

[0074] This embodiment also provides the use of the aforementioned polycarbonate diol containing a bio-based structure in a plasticizer for cellulose acetate.

[0075] Example 3

[0076] This embodiment provides a method for preparing a polycarbonate diol containing a bio-based structure, specifically:

[0077] 1. Transesterification step

[0078] Add the bio-based diol into the reactor, heat it to 150°C, add the composite regulator, and then start to drop dimethyl carbonate; the dropping time of dimethyl carbonate is controlled to be 15 hours. After the dropping of dimethyl carbonate is completed, keep warm and stir for 5 hours, then distill to remove the unreacted dimethyl carbonate and by-product impurities to obtain a homogeneous prepolymer solution.

[0079] Among them, the molar ratio of bio-based diol to dimethyl carbonate is 1:1.03.

[0080] The bio-based diols are bio-based 1,3-propylene glycol and bio-based 1,4-butanediol, and the molar ratio of bio-based 1,3-propylene glycol to bio-based 1,4-butanediol is 7.5:2.5.

[0081] The added amount of the composite regulator is 0.5% of the weight of dimethyl carbonate.

[0082] The preparation method of the composite regulator is:

[0083] 1) Preparation of catalytic carrier

[0084] Under stirring conditions, calcium chloride, aluminum chloride and magnesium chloride are added to an ethanol solution. After stirring for 30 minutes, polyethylene oxide is added, and after stirring evenly, the temperature is lowered to 2°C, and propylene oxide is added dropwise while keeping warm; the addition time of propylene oxide is controlled to be 10 minutes. After the addition of propylene oxide is completed, stirring is continued for 20 minutes; after ultrasonic degassing, the solution is placed in a 45°C temperature environment and allowed to stand for 24 hours to obtain a gel; the gel is placed in a constant temperature drying oven, dried at 65°C for 78 hours, and then transferred to a calcining furnace, heated to 950°C at a heating rate of 1.8°C / min, kept warm and calcined for 3 hours, cooled naturally, and crushed to a particle size of 60μm to obtain a catalytic carrier.

[0085] Wherein, the volume concentration of ethanol solution is 55%.

[0086] The mass ratio of calcium chloride, aluminum chloride, magnesium chloride, ethanol solution, polyethylene oxide and propylene oxide is 4.3:8:1.2:25:0.35:5.3.

[0087] 2) Grafting

[0088] The catalyst carrier is put into 19 times the weight of toluene, and after ultrasonic dispersion, S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is added with stirring, and heated to 100°C at a heating rate of 1.2°C / min. After reflux stirring for 12 hours, the solid is filtered out and dried to obtain a composite regulator.

[0089] Wherein, the weight ratio of the catalytic carrier to S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is 10:5.5.

[0090] 2. Polycondensation step

[0091] Turn on the vacuum pump, control the vacuum degree of the reactor containing the homogeneous prepolymer solution to 800 Pa, heat to 210°C at a heating rate of 1.6°C / min, keep the temperature for 5 hours for polycondensation reaction, filter out and recover the solid matter, and obtain a bio-based structure-containing polycarbonate diol with a predetermined molecular weight and molecular weight distribution.

[0092] The bio-based structure of the polycarbonate diol containing a bio-based structure includes: HO-(CH2)3-OH, HO-(CH2)4-OH; the biocarbon content of the polycarbonate diol containing a bio-based structure is 75.9wt%, the number average molecular weight is 840, the viscosity is 346cp, and the number average molecular weight distribution coefficient (PDI) is 1.4.

[0093] This embodiment also provides a polycarbonate diol containing a bio-based structure, which is prepared by the aforementioned method for preparing the polycarbonate diol containing a bio-based structure.

[0094] This embodiment also provides the use of the aforementioned polycarbonate diol containing a bio-based structure in a plasticizer for cellulose acetate.

[0095] Comparative Example 1

[0096] The method for preparing polycarbonate diol of Example 1 is adopted, except that the addition of the composite regulator is omitted; in the transesterification step, tetrabutoxytitanium is added as a catalyst, and the addition amount of tetrabutoxytitanium is controlled to be 0.2% of the weight of dimethyl carbonate.

[0097] The biocarbon content of the polycarbonate diol containing a bio-based structure prepared in Comparative Example 1 was 73.6 wt %, the number average molecular weight was 890, the viscosity was 343 cp, and the number average molecular weight distribution coefficient (PDI) was 2.1.

[0098] It can be seen that the polycarbonate diol containing a bio-based structure of the present invention uses bio-based 1,3-propylene glycol, bio-based 1,4-butanediol, and dimethyl carbonate in specific dosage ratios as main raw materials, and in the presence of a composite regulator, controls the specific feeding time of dimethyl carbonate and the insulation reaction time after the addition of dimethyl carbonate to carry out an ester exchange reaction to obtain a homogeneous prepolymer solution; at the same time, in the preparation of the composite regulator, calcium chloride, aluminum chloride, magnesium chloride are used in combination with polyethylene oxide and propylene oxide to prepare magnesium-doped calcium aluminum hydrotalcite (i.e., a catalytic carrier) with ester exchange catalytic activity; then, on the basis of the catalytic carrier, the catalytic carrier is subjected to high-temperature calcination activation and magnesium doping treatment in the preparation process to further improve the surface active sites of the catalytic carrier, and then in the grafting composite step, it is ensured that S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is effectively grafted to the magnesium-doped calcium aluminum hydrotalcite. The composite regulator is applied to the surface of the stone to obtain a composite regulator; in the ester exchange reaction stage, the composite regulator controls the progress of the ester exchange reaction through the catalytic effect of the catalytic carrier (magnesium-doped calcium aluminum hydrotalcite) on the ester exchange reaction; then, under the action of the composite regulator, the homogeneous prepolymer solution continues to undergo a polycondensation step through the regulating effect of the S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate grafted on the surface of the catalytic carrier on the polymerization molecular weight, thereby obtaining a polycarbonate diol containing a bio-based structure with a predetermined molecular weight and a narrow molecular weight distribution; the aforementioned technical means cooperate with each other and work synergistically, and can effectively regulate the number average molecular weight of the prepared polycarbonate diol, and the distribution range of the number average molecular weight is narrow; at the same time, the biocarbon content of the polycarbonate diol is increased, the biocompatibility of the polycarbonate diol is increased, and the compatibility of the polycarbonate diol with cellulose acetate is increased, and the plasticizing effect of the polycarbonate diol on cellulose acetate is increased.

[0099] Unless otherwise specified, all percentages used in the present invention are by mass.

[0100] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a polycarbonate diol containing a bio-based structure, characterized in that: Bio-based 1,3-propylene glycol, bio-based 1,4-butanediol and dimethyl carbonate are used as raw materials, and polycarbonate diol containing a bio-based structure is prepared by ester exchange reaction and polycondensation reaction. The bio-based structure is 1,3-propylene glycol introduced into the polycarbonate diol by reacting the raw material bio-based 1,3-propylene glycol, and 1,4-butanediol introduced into the polycarbonate diol by reacting the raw material bio-based 1,4-butanediol; A composite regulator is used in the transesterification reaction, and the addition amount of the composite regulator is 0.4-0.5% of the weight of dimethyl carbonate; The composite regulator is prepared by the following steps: preparing a catalytic carrier and grafting and composite; The method for preparing the catalyst carrier comprises the following steps: adding calcium chloride, aluminum chloride and magnesium chloride into an ethanol solution, stirring evenly, adding polyethylene oxide, stirring evenly, cooling to 0-2°C, and dripping propylene oxide while keeping the temperature; after the dripping of propylene oxide is completed, stirring is continued; after ultrasonic degassing, placing the solution in a temperature environment of 40-45°C, standing to obtain a gel; after drying the gel, calcining at 900-950°C, and grinding evenly to obtain a catalyst carrier; The grafting composite method comprises the following steps: putting the catalyst carrier into toluene, dispersing it uniformly, adding S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate with stirring, heating to 95-100° C., keeping the temperature under reflux and stirring, filtering out the solid matter, and drying the solid matter to obtain the composite regulator; The weight ratio of the catalytic carrier to S-methoxycarbonylbenzyl-S'-trimethoxysilyl trithiocarbonate is 10:5-5.

5.

2. The method for preparing a polycarbonate diol containing a bio-based structure according to claim 1, characterized in that: The method comprises the following steps: an ester exchange step and a polycondensation step; The method of the transesterification step is to add the bio-based diol into a reaction kettle, heat it to 130-170° C., add the composite regulator, and then start to drop dimethyl carbonate; after the dropwise addition of dimethyl carbonate is completed, heat and stir for 4-5 hours, and then distill to remove impurities to obtain a homogeneous prepolymer solution; The bio-based diols are bio-based 1,3-propylene glycol and bio-based 1,4-butanediol; The polycondensation step comprises controlling the vacuum degree of the reaction kettle containing the homogeneous prepolymer solution to 700-800 Pa, heating to 170-230° C., maintaining the temperature for polycondensation reaction, filtering out solids, and obtaining a polycarbonate diol containing a bio-based structure.

3. The method for preparing a polycarbonate diol containing a bio-based structure according to claim 2, characterized in that: In the transesterification step, the dimethyl carbonate is added for a time of 10-15 hours; The molar ratio of bio-based diol to dimethyl carbonate is 1:1-1.03; The molar ratio of bio-based 1,3-propylene glycol to bio-based 1,4-butanediol is 7-7.5:2.5-3.

4. The method for preparing a polycarbonate diol containing a bio-based structure according to claim 2, characterized in that: In the polycondensation step, the heating rate to 170-230°C is 1.2-1.6°C / min; The heat preservation polycondensation time at 170-230℃ is 3-5h.

5. The method for preparing a polycarbonate diol containing a bio-based structure according to claim 1, characterized in that: In the preparation of the catalyst carrier, the dripping time of propylene oxide is controlled to be 5-10 minutes; The standing time in a temperature environment of 40-45°C is 22-24h; The heating rate for calcination at 900-950°C is 1.5-1.8°C / min; The calcination time at 900-950°C is 2-3h.

6. The method for preparing a polycarbonate diol containing a bio-based structure according to claim 1, characterized in that: In the preparation of the catalytic carrier, the volume concentration of the ethanol solution is 50-55%; The mass ratio of calcium chloride, aluminum chloride, magnesium chloride, ethanol solution, polyethylene oxide and propylene oxide is 4-4.3:7.8-8:1-1.2:22-25:0.3-0.35:5-5.

3.

7. The method for preparing a polycarbonate diol containing a bio-based structure according to claim 1, characterized in that: In the graft composite, the weight ratio of the catalyst support to toluene is 1:17-19; The heating rate to 95-100°C is 0.8-1.2°C / min; The stirring time for reflux at 95-100℃ is 10-12h.

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