CN113185684A - Poly (propylene carbonate) and preparation method thereof - Google Patents
Poly (propylene carbonate) and preparation method thereof Download PDFInfo
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- CN113185684A CN113185684A CN202110605008.0A CN202110605008A CN113185684A CN 113185684 A CN113185684 A CN 113185684A CN 202110605008 A CN202110605008 A CN 202110605008A CN 113185684 A CN113185684 A CN 113185684A
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Abstract
The invention provides polypropylene carbonate and a preparation method thereof. The preparation method comprises the following steps: (1) activating an organic solvent, propylene oxide and a catalyst to obtain an activated catalyst; (2) and (2) polymerizing carbon dioxide and propylene oxide in the presence of the activated catalyst obtained in the step (1) and an organic solvent to obtain the polypropylene carbonate. According to the invention, the catalyst is activated, and then the activated catalyst is used for catalyzing propylene oxide and carbon dioxide to carry out polymerization reaction in the presence of an organic solvent, so that the prepared polycarbonate has ultrahigh molecular weight and good mechanical property.
Description
Technical Field
The invention belongs to the technical field of polymer synthesis, and particularly relates to polypropylene carbonate and a preparation method thereof.
Background
Carbon dioxide is a common greenhouse gas and a cheap and easily available carbon resource, and researches on fixation and utilization of carbon dioxide have been widely focused, wherein researches on synthesis of polymer materials by using carbon dioxide as a raw material become one of hot spots in the research field of fixation and utilization of carbon dioxide. Since the aliphatic polycarbonate with biodegradability is obtained by the first copolymerization of carbon dioxide and epoxide by professor in japan in 1969, polypropylene carbonate (PPC), which is a copolymerization product of carbon dioxide and propylene oxide, has become the most industrially valuable of all carbon dioxide copolymers and has been practically used in the fields of foam, film material, etc. through research of recent 50 years.
CN102391635A discloses a biodegradable foam plastic and a preparation method thereof. The biodegradable foamed plastic takes a biodegradable polymer polypropylene carbonate synthesized by carbon dioxide and propylene oxide as a matrix, partial biodegradable materials (such as polylactic acid, polybutylene succinate, polybutylene adipate or polybutylene terephthalate) are added to improve the use temperature of the biodegradable polymer polypropylene carbonate, a chain extender is added in the formula for improving the performance, a small amount of nucleating agent is also added in the formula, the special foaming material is prepared by melt mixing or solution mixing, then a plastic extruder is used for carrying out physical foaming to prepare a plastic foamed product, the mixing and foaming processes can also be simultaneously completed on the same extruder, and the polypropylene carbonate material can be widely used in the field of packaging after being foamed.
CN101348605A discloses a degradable aliphatic polycarbonate composite film material and a preparation method thereof. The composite film material is formed by blending and compounding polypropylene carbonate and polyethylene glycol, wherein the content of the polyethylene glycol is 20-60% and the content of the polypropylene carbonate is 40-80% in percentage by weight; the preparation method is that the poly propylene carbonate and the polyethylene glycol are respectively dissolved in organic solvent to prepare solution; uniformly mixing the two solutions in proportion, volatilizing at room temperature to remove most of the solvent, and casting the mixed solution into a flat glass mold; and drying in vacuum to constant mass to obtain the PPC-PEG composite film material.
For the preparation of polypropylene carbonate, the current rare earth ternary catalyst and organic zinc carboxylate catalyst firstly realize the industrial production of PPC by the characteristics of simple synthesis and low cost, however, the catalytic mechanism of a heterogeneous catalytic system is difficult to be clear, the catalytic efficiency of the heterogeneous catalytic system cannot be effectively improved all the time, and the production of the byproduct Propylene Carbonate (PC) in the polymerization process is positively correlated with the reaction temperature, so the reaction temperature for industrially preparing PPC is generally controlled below 75 ℃, the reaction time is generally controlled above 10 hours to achieve the appropriate conversion rate, and the conversion rate of propylene oxide is only 30-40 percent.
The initiation time exists in the early stage of polymerization in both the rare earth ternary catalytic system and the organic zinc carboxylate catalytic system, and the initiation time affects the efficiency of polymerization reaction, and meanwhile, too long initiation time can provide the content of PC (polycarbonate) serving as a byproduct and increase the subsequent separation cost, and on the other hand, the continuous consumption of monomers can also cause the increase of the viscosity of the polymerization system in the later stage along with the progress of polymerization reaction. Al-Wahaibi T et Al (Roles of drag reducing polymers in single-and multi-phase flows [ J ], Al-Wahaibi T et Al, Chemical Engineering Research & Design,2014,92(11): 2153-. CN112358607A discloses a preparation method of a carbon dioxide-propylene oxide copolymer, the technical scheme greatly reduces the viscosity of a system at the later stage of polymerization reaction in a high-pressure solution polymerization mode, and effectively improves the conversion rate of propylene oxide in the catalytic polymerization process of a rare earth ternary catalyst and a zinc dicarboxylate catalyst, however, the PPC prepared by the method has the highest number average molecular weight of only 250kDa and lower number average molecular weight.
One of the main advantages of the thin film material prepared from the PPC material is that the melt strength of the PPC material is high, and a thin film is easier to prepare, so that the unit area cost is reduced, the molecular weight of the PPC material is increased, the melt strength of the PPC material can be greatly increased, and in the process of blowing a film product, a large-diameter bubble can be blown, thereby being beneficial to the preparation of products such as a wide mulching film. Therefore, how to provide a preparation method of ultra-high molecular weight polypropylene carbonate (UHMW-PPC) becomes a technical problem to be solved urgently at present.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide polypropylene carbonate and a preparation method thereof. According to the invention, the catalyst is activated, and then the polymerization reaction of the propylene oxide and the carbon dioxide is catalyzed by the activated catalyst in the presence of an organic solvent, so that the prepared polycarbonate has ultrahigh molecular weight and good mechanical property, and the prepared polypropylene carbonate is suitable for preparing mulching films, packaging, disposable tableware, medical materials or battery barrier materials and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for preparing polypropylene carbonate, comprising the steps of:
(1) activating an organic solvent, propylene oxide and a catalyst to obtain an activated catalyst;
(2) and (2) polymerizing carbon dioxide and propylene oxide in the presence of the activated catalyst obtained in the step (1) and an organic solvent to obtain the polypropylene carbonate.
According to the invention, the catalyst is activated, so that the catalyst can catalyze the copolymerization of the propylene oxide and the carbon dioxide in an organic solvent more easily, and the catalytic efficiency of the catalyst and the conversion rate of the propylene oxide are improved; in the polymerization process of carbon dioxide and propylene oxide, the use of the organic solvent effectively reduces the viscosity of a system at the later stage of the polymerization reaction, thereby reducing the possibility of the molecular chain fracture of the polypropylene carbonate caused by the turbulent flow in the polymerization reaction, greatly improving the molecular weight of the product, and the prepared polypropylene carbonate has higher molecular weight and better mechanical property.
The following is a preferred technical solution of the present invention, but not a limitation to the technical solution provided by the present invention, and the object and advantageous effects of the present invention can be better achieved and achieved by the following preferred technical solution.
In a preferred embodiment of the present invention, the organic solvent in step (1) is selected from any one or a combination of at least two of 1, 4-dioxane, 1, 3-dioxolane, and dichloromethane.
Preferably, the volume ratio of the organic solvent in the step (1) to the propylene oxide in the step (1) is (0.5-1.5): 1, and may be, for example, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5: 1.
Preferably, the content of the propylene oxide in the step (1) is 5 to 20% by mass, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or the like, based on 100% by mass of the sum of the propylene oxides in the step (1) and the step (2).
As a preferred embodiment of the present invention, the catalyst is a heterogeneous catalyst.
Preferably, the catalyst is selected from any one of a three-way rare earth catalyst, a zinc organocarboxylate catalyst, a double metal cyanide catalyst, or a modified double metal cyanide catalyst or a combination of at least two thereof.
Preferably, the organic solvent in step (2) is selected from any one of 1, 4-dioxane, 1, 3-dioxolane or dichloromethane or the combination of at least two of the two.
Preferably, the mass ratio of the propylene oxide in the step (2) to the catalyst in the step (1) is (7-15: 1), and may be, for example, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1 or 15: 1.
Preferably, the volume ratio of the propylene oxide in the step (2) to the organic solvent in the step (2) is 1 (1 to 1.5), and may be, for example, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1.5:1, or the like.
Preferably, the water content of the organic solvent and propylene oxide in step (1) and step (2) is less than 50ppm, and may be, for example, 10ppm, 15ppm, 20ppm, 25ppm, 30ppm, 35ppm, 40 or 45ppm, etc.
As a preferred technical scheme of the invention, the activating method is ultrasonic.
Preferably, the power of the ultrasound is 1.5-20W/cm2For example, it may be 1.5W/cm2、2W/cm2、4W/cm2、6W/cm2、8W/cm2、10W/cm2、12W/cm2、14W/cm2、16W/cm2、18W/cm2Or 20W/cm2And the like.
Preferably, the temperature of the activation is 65 to 75 ℃, for example, 65 ℃, 66 ℃, 67 ℃, 68 ℃, 69 ℃, 70 ℃, 71 ℃, 72 ℃, 73 ℃, 74 ℃ or 75 ℃.
Preferably, the activation time is 0.5 to 2 hours, for example, 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 0.9 hour, 1 hour, 1.1 hour, 1.2 hour, 1.3 hour, 1.4 hour, 1.5 hour, 1.6 hour, 1.7 hour, 1.8 hour, 1.9 hour or 2 hours, etc.
As a preferred technical scheme of the invention, the method also comprises a post-treatment step after the activation.
Preferably, the post-treatment method is to dry the activated catalyst and then grind.
Preferably, the method of drying is freeze drying.
Preferably, the temperature of the freeze-drying is 20 to 55 ℃, for example, 20 ℃, 22 ℃, 25 ℃, 27 ℃, 30 ℃, 33 ℃, 36 ℃, 39 ℃, 40 ℃, 42 ℃, 46 ℃, 50 ℃, 52 ℃ or 55 ℃ and the like.
Preferably, the freeze-drying time is 0.5 to 2 hours, and may be, for example, 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 0.9 hour, 1 hour, 1.1 hour, 1.2 hour, 1.3 hour, 1.4 hour, 1.5 hour, 1.6 hour, 1.7 hour, 1.8 hour, 1.9 hour, 2 hours, or the like.
Preferably, the milling is carried out in the presence of an inert gas.
Preferably, the grinding method is grinding by a ball mill.
Preferably, the grinding time is 0.5 to 2 hours, for example, 0.5 hour, 0.6 hour, 0.7 hour, 0.8 hour, 0.9 hour, 1 hour, 1.1 hour, 1.2 hour, 1.3 hour, 1.4 hour, 1.5 hour, 1.6 hour, 1.7 hour, 1.8 hour, 1.9 hour or 2 hours, etc.
As a preferred embodiment of the present invention, the polymerization in the step (2) is carried out in a high-pressure reactor.
Preferably, the polymerization temperature in step (2) is 70 to 100 ℃, for example, 70 ℃, 72 ℃, 75 ℃, 77 ℃, 80 ℃, 83 ℃, 85 ℃, 88 ℃, 90 ℃,92 ℃, 95 ℃, 97 ℃ or 100 ℃.
Preferably, the polymerization time in the step (2) is 10-30 h, for example, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h or 30h, etc.
Preferably, the pressure of the polymerization in the step (2) is 4 to 15MPa, and may be, for example, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, or 15 MPa.
As a preferable embodiment of the present invention, the polymerization in the step (2) further comprises a post-treatment step after completion of the polymerization.
Preferably, the method of post-processing comprises: cooling, releasing pressure, washing and drying.
As a preferred technical scheme of the invention, the preparation method specifically comprises the following steps:
(1) at 65-75 ℃, the organic solvent, the propylene oxide and the catalyst are added at 1.5-20W/cm2Carrying out ultrasonic treatment for 0.5-2 h at the power of (1), carrying out freeze drying for 0.5-2 h at the temperature of 20-55 ℃, and then grinding for 0.5-2 h in an inert gas atmosphere to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with an organic solvent in a high-pressure reaction kettle, heating to 70-100 ℃, adding propylene oxide into the mixture, filling carbon dioxide into the mixture, polymerizing for 10-30 hours under the condition that the pressure is 4-15 MPa, cooling, releasing the pressure, washing and drying to obtain the polypropylene carbonate.
In a second aspect, the present invention provides polypropylene carbonate prepared by the preparation method according to the first aspect.
In a preferred embodiment of the present invention, the weight average molecular weight of the polypropylene carbonate is 1000 to 2000kDa, and may be, for example, 1000kDa, 1100kDa, 1200kDa, 1300kDa, 1400kDa, 1500kDa, 1600kDa, 1700kDa, 1800kDa, 1900kDa, 2000kDa, or the like.
The polypropylene carbonate provided by the invention can be used in the fields of mulching films, packaging and the like.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the catalyst is activated, and then the activated catalyst catalyzes propylene oxide and carbon dioxide to carry out polymerization reaction in the presence of an organic solvent, so that the propylene oxide has a good conversion rate, the conversion rate is up to 96.7%, and the prepared polycarbonate has an ultrahigh molecular weight and good mechanical property, the weight average molecular weight is 1005-1807 kDa, the tensile strength is 19.8-38.4 MPa, the elongation at break is 388-488%, and the melt viscosity is 51300-97500 Pa-s.
Drawings
FIG. 1 is a GPC chart of polypropylene carbonate prepared in example 2 of the present invention;
FIG. 2 is a diagram showing the preparation of polypropylene carbonate according to example 2 of the present invention1H-NMR spectrum.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
The catalysts in the following examples and comparative examples were prepared as follows:
diethyl zinc-glycerol-yttrium trichloroacetate ternary rare earth catalyst: the diethyl zinc-glycerol-yttrium trichloroacetate ternary rare earth catalyst is prepared according to the preparation method of the ternary catalyst disclosed in CN1250603C, wherein Y (CCl)3COO)30.0015mol, 0.03mol of glycerol and ZnEt20.03 mol;
zinc glutarate (ZnGA) catalyst: a zinc glutarate (ZnGA) catalyst was prepared according to the preparation method of example 1 in CN 105418907A;
modified double metal cyanide: the modified double metal cyanide compound was prepared according to the preparation method of example 1 of CN 102432857A.
Example 1
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and diethyl zinc-glycerol-yttrium trichloroacetate ternary rare earth catalyst are added at the temperature of 70 ℃ and the temperature is controlled to be 2W/cm2Ultrasonic treatment for 1h at the power of (1), freeze drying for 2h at the temperature of 20 ℃, and grinding for 0.5h in argon gas to obtain the activated catalystAn agent;
(2) mixing the activated catalyst obtained in the step (1) with 1, 4-dioxane (200mL) in a high-pressure reaction kettle, heating to 70 ℃, adding propylene oxide (180mL) into the mixture, introducing carbon dioxide into the mixture, carrying out polymerization reaction for 12 hours under the conditions of the rotation speed of 500rpm and the pressure of 4.2MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10 hours under the conditions of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 148.8g of polypropylene carbonate.
According to the content of the carbonate and the molecular structure of the product, 89.9g of propylene oxide consumed by the product can be calculated, the feeding amount of the propylene oxide is 180ml, the density is 0.83g/ml, 149.4g of the propylene oxide is fed in total, and the conversion rate of the obtained propylene oxide is 60.1%;
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 94.5 percent, and the content of the byproduct propylene carbonate is 4.7 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1492kDa and the molecular weight distribution was 3.83 as determined by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 2
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and diethyl zinc-glycerol-yttrium trichloroacetate ternary rare earth catalyst are added at 5W/cm at 70 DEG C2Carrying out ultrasonic treatment for 1.5h at the power of (1), carrying out freeze drying for 1h at the temperature of 40 ℃, and then grinding for 1h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with dichloromethane (200mL) in a high-pressure reaction kettle, heating to 75 ℃, adding epoxypropane (180mL) and filling carbon dioxide into the mixture, carrying out a polymerization reaction for 12h under the conditions of a rotation speed of 500rpm and a pressure of 4.2MPa, cooling to below 40 ℃, slowly releasing pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10h under the conditions of 40 ℃ and a vacuum degree of-0.1 MPa to obtain 166.6g of polypropylene carbonate, wherein the conversion rate of the epoxypropane is 66.6%.
The polypropylene carbonate prepared by the present invention was subjected to GPC test with narrow distribution polystyrene as a standard sample and dichloromethane as a mobile phase, and the spectrogram thereof is shown in fig. 1, as can be seen from fig. 1, the weight average molecular weight of the polypropylene carbonate prepared by this example is 1807kDa, and the molecular weight distribution is 4.28.
Preparation of the Polypropylene carbonate obtained in this example1The H-NMR spectrum is shown in figure 2,1H-NMR (400MHz, D-DMSO): the ester bond content of the polypropylene carbonate chain segment can be represented by the formula (A)4.90-A4.55)/(A4.90-A4.55+A3.60The content of the byproduct propylene carbonate can be obtained by calculation according to the formula A4.55/(A4.90+A3.60Calculated as,/3), wherein A4.90Corresponding to the integrated area at 4.90ppm, which is attributed to polypropylene carbonate methine hydrogen and propylene carbonate methine hydrogen, A4.55Corresponding to an integrated area at 4.55ppm, one methylene hydrogen, A, attributed to propylene carbonate3.60Corresponding to the integrated area at 3.60ppm, two methylene hydrogens and one methine hydrogen were assigned to the polypropylene oxide. As can be seen from fig. 2, the content of ester in the polypropylene carbonate segment is 95.9%, and the by-product propylene carbonate is 5.0%.
Example 3
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and zinc glutarate catalyst (4g) were mixed at 10W/cm at 70 deg.C2Carrying out ultrasonic treatment for 1.5h at the power of (1), carrying out freeze drying for 2h at the temperature of 55 ℃, and then grinding for 1h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with 1, 4-dioxane (200mL) in a high-pressure reaction kettle, heating to 70 ℃, adding propylene oxide (180mL) into the mixture, introducing carbon dioxide into the mixture, carrying out polymerization reaction for 12 hours under the conditions of the rotation speed of 500rpm and the pressure of 4.2MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10 hours under the conditions of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 152.3g of polypropylene carbonate, wherein the conversion rate of the propylene oxide is 61.2%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 95.1 percent, and the content of the byproduct propylene carbonate is 4.4 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1620kDa and the molecular weight distribution was 4.62 by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 4
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and zinc glutarate catalyst (4g) were mixed at 20W/cm at 70 deg.C2Carrying out ultrasonic treatment for 2h at the power of (1), carrying out freeze drying for 0.5h at the temperature of 30 ℃, and then grinding for 0.5h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with dichloromethane (200mL) in a high-pressure reaction kettle, heating to 70 ℃, adding epoxypropane (180mL) and filling carbon dioxide into the mixture, carrying out a polymerization reaction for 12h under the conditions of a rotation speed of 500rpm and a pressure of 4.2MPa, cooling to below 40 ℃, slowly releasing pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10h under the conditions of 40 ℃ and a vacuum degree of-0.1 MPa to obtain 158.8g of polypropylene carbonate, wherein the conversion rate of the epoxypropane is 63.7%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 95.4 percent, and the content of the byproduct propylene carbonate is 4.9 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1540kDa and the molecular weight distribution was 4.46, as measured by GPC, using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 5
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and ethyl zinc were added at 70 deg.CThe ternary rare earth catalyst of-glycerin-trichloroacetic acid yttrium is at 12W/cm2Carrying out ultrasonic treatment for 1h at the power of (1), carrying out freeze drying for 2h at the temperature of 40 ℃, and then grinding for 0.5h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with 1, 4-dioxane (200mL) in a high-pressure reaction kettle, heating to 90 ℃, adding propylene oxide (180mL) into the mixture, introducing carbon dioxide into the mixture, carrying out polymerization reaction for 12 hours under the conditions of the rotation speed of 500rpm and the pressure of 9.0MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10 hours under the conditions of the temperature of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 226.7g of polypropylene carbonate, wherein the conversion rate of the propylene oxide is 96.7%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 92.6 percent, and the content of the byproduct propylene carbonate is 4.8 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1005kDa and the molecular weight distribution was 2.88 by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 6
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and zinc glutarate catalyst (4g) were mixed at 10W/cm at 70 deg.C2Carrying out ultrasonic treatment for 1.5h at the power of (1), carrying out freeze drying for 0.5h at the temperature of 30 ℃, and then grinding for 2h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with 1, 4-dioxane (200mL) in a high-pressure reaction kettle, heating to 90 ℃, adding propylene oxide (180mL) into the mixture, introducing carbon dioxide into the mixture, carrying out a polymerization reaction for 12 hours under the conditions of the rotation speed of 500rpm and the pressure of 9MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10 hours under the conditions of the temperature of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 152.3g of polypropylene carbonate, wherein the conversion rate of the propylene oxide is 62.4%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 92.2 percent, and the content of the byproduct propylene carbonate is 5.0 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1108kDa and the molecular weight distribution was 2.72 by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 7
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 4-dioxane (20mL), propylene oxide (20mL) and modified double metal cyanide (0.2g) were mixed at 1.5W/cm at 70 deg.C2Carrying out ultrasonic treatment for 1h at the power of (1), carrying out freeze drying for 1.5h at the temperature of 50 ℃, and then grinding for 1h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with 1, 4-dioxane (200mL) in a high-pressure reaction kettle, heating to 70 ℃, adding propylene oxide (180mL) into the mixture, introducing carbon dioxide into the mixture, carrying out polymerization reaction for 12h under the conditions of the rotation speed of 500rpm and the pressure of 12MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10h under the conditions of the temperature of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 152.3g of polypropylene carbonate, wherein the conversion rate of the propylene oxide is 75.8%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 90.5 percent, and the content of the byproduct propylene carbonate is 4.8 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1105kDa and the molecular weight distribution was 5.47 by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 8
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) 1, 3-dioxy pentacyclic (15mL), epoxypropane (10mL) and diethyl zinc-glycerin-trichloroacetic acid yttrium ternary rare earth catalyst are added at the temperature of 75 ℃ and the temperature is controlled at 20W/cm2Ultrasonic treatment is carried out for 0.5h under the power of (1), freeze drying is carried out for 1.5h at the temperature of 50 ℃, grinding is carried out for 0.5h in argon gas,obtaining an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with 1, 4-dioxane (190mL) in a high-pressure reaction kettle, heating to 100 ℃, adding propylene oxide (190mL) into the mixture, introducing carbon dioxide into the mixture, carrying out polymerization reaction for 30 hours under the conditions of the rotation speed of 500rpm and the pressure of 4MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10 hours under the conditions of the temperature of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 148.8g of polypropylene carbonate, wherein the conversion rate of the propylene oxide is 57.3%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 93.7 percent, and the content of the byproduct propylene carbonate is 5.5 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1320kDa and the molecular weight distribution was 3.21 by GPC using narrow distribution polystyrene as the standard and dichloromethane as the mobile phase.
Example 9
This example provides a polypropylene carbonate and a method for preparing the same, the method comprising:
(1) at 65 ℃, dichloromethane (20mL), propylene oxide (40mL) and diethyl zinc-glycerol-yttrium trichloroacetate ternary rare earth catalyst are added at 10W/cm2Carrying out ultrasonic treatment for 1h at the power of (1), carrying out freeze drying for 0.8h at the temperature of 20 ℃, and then grinding for 1.5h in argon gas to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with 1, 3-dioxolane (320mL) in a high-pressure reaction kettle, heating to 70 ℃, adding epoxypropane (160mL) into the mixture, carrying out polymerization reaction for 10 hours under the conditions of the rotation speed of 500rpm and the pressure of 15MPa, cooling to below 40 ℃, slowly releasing the pressure to normal pressure, opening the high-pressure reaction kettle to obtain a mixed product, washing the mixed product for 3 times by using absolute ethyl alcohol, and drying for 10 hours under the conditions of the temperature of 40 ℃ and the vacuum degree of-0.1 MPa to obtain 148.8g of polypropylene carbonate, wherein the conversion rate of the epoxypropane is 58.7%.
1H-NMR shows that the content of ester in the polypropylene carbonate chain segment is 98.2 percent, and the content of the byproduct propylene carbonate is 4.1 percent; the weight average molecular weight of the polypropylene carbonate prepared in this example was 1210kDa and the molecular weight distribution was 3.55 by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Example 10
This example provides a polypropylene carbonate and a method for preparing the same, which are different from example 3 in that in step (1), 1, 4-dioxane (20mL), propylene oxide (20mL) and a zinc glutarate catalyst (4g) are stirred and activated at 70 ℃, the stirring speed is 200rpm, after 1 hour, freeze-drying is performed at 55 ℃ for 2 hours, and then grinding is performed in argon for 1 hour to obtain an activated catalyst; other conditions were the same as in example 3.
In the example, the conversion rate of propylene oxide was 34.1%, the ester content in the polypropylene carbonate segment was 92.0% as measured by 1H-NMR, and the byproduct propylene carbonate was 7.8%; the weight average molecular weight of the polypropylene carbonate prepared in this example was 348kDa and the molecular weight distribution was 3.63 by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
Comparative example 1
This comparative example provides polypropylene carbonate and a method for preparing the same, differing from example 1 only in that 1, 4-dioxane (200mL) is not added in step (2), and the other conditions are the same as example 1.
In the comparative example, the conversion of propylene oxide was 37.8%, the ester content in the polypropylene carbonate segment was 92.5% as measured by 1H-NMR, and the by-product propylene carbonate was 7.7%; the weight average molecular weight of the polypropylene carbonate prepared by the comparative example was 411kDa and the molecular weight distribution was 3.25, as measured by GPC using narrow distribution polystyrene as a standard and dichloromethane as a mobile phase.
The polypropylene carbonate provided in the above examples and comparative examples was tested for its properties according to the following test criteria:
tensile strength, elongation at break and elastic modulus: testing according to GB/1040.2-2006, wherein the stretching speed is 50 mm/min;
melt viscosity: the test was carried out using a TA Instruments conversion HR-1 rotary rheometer, with a test temperature of 160 ℃ and an angular frequency of 10 rad/s.
The test results of the properties of the polypropylene carbonate provided in the above examples and comparative examples are shown in the following table 1:
TABLE 1
As shown in Table 1, the catalyst is activated, and then the activated catalyst catalyzes the polymerization reaction of the propylene oxide and carbon dioxide in the presence of an organic solvent, so that the propylene oxide has a good conversion rate which is up to 96.7%, and the prepared polycarbonate has an ultrahigh molecular weight and good mechanical properties, the weight-average molecular weight is 1005-1807 kDa, the tensile strength is 19.8-38.4 MPa, the elongation at break is 388-488%, and the melt viscosity is 51300-97500 Pa & s.
When the catalyst was activated by stirring (example 10), the conversion of propylene oxide was low, only 34.1%, as compared to example 3, and thus the polypropylene carbonate prepared had a low weight average molecular weight, poor tensile strength, elongation at break and elastic modulus, and a low melt viscosity. Therefore, the method has the advantages that the conversion rate of the propylene oxide is high through a specific activation method, the weight average molecular weight of the prepared polypropylene carbonate is high, and the mechanical property is good.
In comparison with example 1, if an organic solvent is not added in step (2) (comparative example 1), the conversion of propylene oxide is low, only 37.8%, and thus the prepared polypropylene carbonate has a low weight average molecular weight, poor tensile strength, elongation at break and elastic modulus, and a low melt viscosity. Therefore, the method has the advantages that the conversion rate of the propylene oxide is high by a solution polymerization method, the weight average molecular weight of the prepared polypropylene carbonate is high, and the mechanical property is good.
In conclusion, the catalyst is activated, and then the activated catalyst catalyzes the polymerization reaction of the propylene oxide and the carbon dioxide in the presence of the organic solvent, so that the propylene oxide has higher conversion rate, and the prepared polycarbonate has ultrahigh molecular weight and better mechanical property.
The applicant states that the present invention is illustrated by the detailed process flow of the present invention through the above examples, but the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. It will be apparent to those skilled in the art that any modifications to the invention, equivalent substitutions of selected materials and additions of adjunct ingredients, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. A preparation method of polypropylene carbonate is characterized by comprising the following steps:
(1) activating an organic solvent, propylene oxide and a catalyst to obtain an activated catalyst;
(2) and (2) polymerizing carbon dioxide and propylene oxide in the presence of the activated catalyst obtained in the step (1) and an organic solvent to obtain the polypropylene carbonate.
2. The preparation method according to claim 1, wherein the organic solvent in step (1) is selected from any one or a combination of at least two of 1, 4-dioxane, 1, 3-dioxolane or dichloromethane;
preferably, the volume ratio of the organic solvent in the step (1) to the propylene oxide in the step (1) is (0.5-1.5): 1;
preferably, the content of the propylene oxide in the step (1) is 5-20% by mass based on 100% by mass of the total amount of the propylene oxide in the step (1) and the propylene oxide in the step (2).
3. The production method according to claim 1 or 2, characterized in that the catalyst is a heterogeneous catalyst;
preferably, the catalyst is selected from any one of a ternary rare earth catalyst, a zinc organic carboxylate catalyst, a double metal cyanide catalyst or a modified double metal cyanide catalyst or a combination of at least two of the same;
preferably, the organic solvent in step (2) is selected from any one or a combination of at least two of 1, 4-dioxane, 1, 3-dioxolane or dichloromethane;
preferably, the mass ratio of the propylene oxide in the step (2) to the catalyst in the step (1) is (7-15): 1;
preferably, the volume ratio of the propylene oxide in the step (2) to the organic solvent in the step (2) is 1 (1-1.5);
preferably, the water content of the organic solvent and the propylene oxide in the steps (1) and (2) are less than 50 ppm.
4. The production method according to any one of claims 1 to 3, wherein the method of activation is sonication;
preferably, the power of the ultrasound is 1.5-20W/cm2；
Preferably, the activation temperature is 65-75 ℃;
preferably, the activation time is 0.5-2 h.
5. The method according to any one of claims 1 to 4, further comprising a step of post-treatment after the activation;
preferably, the method of the post-treatment is to dry the activated catalyst and then grind;
preferably, the method of drying is freeze drying;
preferably, the temperature of the freeze drying is 20-55 ℃;
preferably, the freeze drying time is 0.5-2 h;
preferably, the milling is carried out in the presence of an inert gas;
preferably, the grinding method is grinding by a ball mill;
preferably, the grinding time is 0.5-2 h.
6. The production method according to any one of claims 1 to 5, wherein the polymerization in the step (2) is carried out in an autoclave;
preferably, the temperature of the polymerization in the step (2) is 70-100 ℃;
preferably, the polymerization time in the step (2) is 10-30 h;
preferably, the pressure of the polymerization in the step (2) is 4-15 MPa.
7. The production method according to any one of claims 1 to 6, wherein the polymerization of step (2) is completed and then a post-treatment step is further included;
preferably, the method of post-processing comprises: cooling, releasing pressure, washing and drying.
8. The method according to any one of claims 1 to 7, comprising in particular the steps of:
(1) at 65-75 ℃, the organic solvent, the propylene oxide and the catalyst are added at 1.5-20W/cm2Carrying out ultrasonic treatment for 0.5-2 h at the power of (1), carrying out freeze drying for 0.5-2 h at the temperature of 20-55 ℃, and then grinding for 0.5-2 h in an inert gas atmosphere to obtain an activated catalyst;
(2) mixing the activated catalyst obtained in the step (1) with an organic solvent in a high-pressure reaction kettle, heating to 70-100 ℃, adding propylene oxide into the mixture, filling carbon dioxide into the mixture, polymerizing for 10-30 hours under the condition that the pressure is 4-15 MPa, cooling, releasing the pressure, washing and drying to obtain the polypropylene carbonate.
9. A polypropylene carbonate produced by the production method as claimed in any one of claims 1 to 8.
10. The polypropylene carbonate according to claim 9, wherein the weight average molecular weight of the polypropylene carbonate is 1000 to 2000 kDa.
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| CN114479043A (en) * | 2022-01-18 | 2022-05-13 | 上海华峰新材料研发科技有限公司 | High-impact carbon dioxide random copolymer and preparation method and application thereof |
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