Preparation method of water-soluble aliphatic polycarbonate diol

Abstract

The invention discloses a preparation method of aliphatic polycarbonate diol with water solubility. The preparation method comprises the following steps: adding ethylene oxide, a non-metal catalyst and a chain transfer agent into a high-pressure reaction kettle, introducing carbon dioxide, and carrying out ring-opening polymerization reaction to obtain the water-soluble aliphatic polycarbonate diol. The innovation of the invention lies in that ethylene oxide is used as a reaction monomer for the first time, a commercialized non-metal catalyst is continuously used, and the aliphatic polycarbonate diol with water solubility is synthesized by a one-step method. The raw materials used for preparation are low in price, no metal catalyst is left in the synthesis process, the reaction condition is mild, the polymerization temperature is low, and the requirement for industrial production equipment is not high. The polycarbonate content and the polyether content are controllable in a large range, the molecular weight distribution is narrow, and the molecular weight is controllable. The aliphatic polycarbonate diol provided by the invention can be used for producing polyurethane foam materials, elastomers, water-based coatings, sealants, adhesives and the like with more special properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material synthesis, and specifically to a preparation method of an aliphatic polycarbonate diol with water solubility. Background Art

[0002] In the traditional synthesis methods of low-molecular-weight aliphatic polycarbonate diols, the phosgene method for synthesizing aliphatic polycarbonate diols is the most commonly used method. This method is costly and the synthesis raw materials and process are highly dangerous, not meeting the production requirements of green chemistry. The transesterification method of carbonate and diol is also a relatively commonly used method, but it has high energy consumption and the by-products need to be removed during the preparation process, which requires high equipment requirements, so the production cost is also relatively high. In the ring-opening polymerization method of cyclic carbonate, the cyclic carbonates with five or more rings are expensive, few in variety, high in cost, and difficult to open the ring due to their low activity, so they are also less used. Currently, the ring-opening polymerization of propylene oxide to synthesize aliphatic polycarbonate diols is used more often, but the diols synthesized by this method have poor fluidity, the content of polyether and polycarbonate cannot be regulated at all, do not have water solubility, and have relatively high costs, so their applications are relatively limited.

[0003] Ethylene oxide is the cheapest epoxy monomer, but due to its simplest chemical structure and highest chemical activity, it is extremely difficult to control the reaction conditions to obtain the ideal target product. Therefore, no one has explored its use in the synthesis of diols at present. In view of the fact that the existing polymer PEO (polyethylene oxide) on the market has high water solubility and excellent chain flexibility, the present invention for the first time explores the ring-opening copolymerization reaction of ethylene oxide and carbon dioxide. Under the action of a chain transfer agent, the synthesis of low-molecular-weight poly(ethylene carbonate) diols can be achieved, and the diols have certain water solubility, good chain flexibility, and controllable molecular structure. Therefore, compared with the diols obtained by the ring-opening copolymerization of other types of epoxy monomers in the traditional method, the performance is greatly improved and the application prospect is wider. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a preparation method of an aliphatic polycarbonate diol with solubility and low cost. The present invention uses "organic boron / organic amine" as a non-metallic catalyst, and under the condition of a chain transfer agent, synthesizes an aliphatic polycarbonate diol with water solubility, controllable molecular weight, and controllable content of polyether and polycarbonate through the copolymerization of ethylene oxide and CO2.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A preparation method of a water-soluble aliphatic polycarbonate diol, comprising the following steps: adding ethylene oxide, a non-metallic catalyst and a chain transfer agent into a high-pressure reaction kettle, introducing carbon dioxide, and carrying out ring-opening polymerization reaction to obtain a water-soluble aliphatic polycarbonate diol; the structural formula of the water-soluble aliphatic polycarbonate diol is shown in the following formula 1: a = 1 - 60, b = 1 - 20, c = 1 - 70, a, b, and c are all integers, and with the change of reaction conditions, their relative contents change significantly, and the three do not correspond to each other from small to large or simply change in a complementary manner;

[0007]

[0008] The preparation process is as follows:

[0009]

[0010] Preferably, the chain transfer agent is ethylene glycol, propylene glycol, tripropylene glycol, neopentyl glycol, 1,3 - propanediol, 1,4 - butanediol, 1,2 - butanediol, 1,3 - butanediol, 2,3 - butanediol, 1,6 - hexanediol, 1,4 - cyclohexanediol, cyclohexanedimethanol, hydroquinone or resorcinol.

[0011] Preferably, the molar ratio of ethylene oxide to the chain transfer agent is 100 - 200:1. Preferably, the pressure of carbon dioxide is 0.1 - 3 Mpa.

[0012] Preferably, the reaction temperature is 40 - 55 °C, and the reaction time is 12 - 36 h.

[0013] Preferably, the non-metallic catalyst is a Lewis acid-base pair composite catalyst; the Lewis acid is an organoboron compound; the Lewis base is an organic amine or an organic amine salt, and the molar ratio of the Lewis acid to the Lewis base is 3 - 8:0.8; the molar ratio of ethylene oxide to the Lewis base is 1500 - 3000:0.8.

[0014] Preferably, the organoboron compound is triethylboron; the organic amine or the organic amine salt is tetra-n-butylammonium chloride or tetra-n-butylammonium bromide.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1. In view of the problem that the prior art uses propylene oxide for ring-opening polymerization to synthesize aliphatic polycarbonate diol, and the obtained diol does not have water solubility and the molecular structure is completely uncontrollable, the innovation of the present invention is to first use ethylene oxide as a reaction monomer, adopt a commercial non-metallic catalyst, and synthesize a water-soluble aliphatic polycarbonate diol by a one-step method.

[0017] 2. The raw materials used in the preparation of the present invention are inexpensive, there is no residue of metal catalyst in the synthesis process, the reaction conditions are mild, the polymerization temperature is low, and the requirements for industrial production equipment are not high, which is conducive to the expansion of industrial production.

[0018] 3. The content of polycarbonate and polyether in the present invention can be controlled within a wide range (taking the content of polycarbonate as an example: 3-95%), with a narrow molecular weight distribution and a controllable molecular weight (300-6000 g / mol), which cannot be achieved in systems using other epoxy monomers. In such systems, only aliphatic polycarbonate diols with a fixed composition (the content of polycarbonate is above 90% and cannot be regulated) can be obtained. The aliphatic polycarbonate diol of the present invention can replace the currently widely used poly(propylene carbonate) diol and be used to produce polyurethane foam materials, elastomers, waterborne coatings, sealants, adhesives, etc. with more special properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings are used to further clearly illustrate and explain the technical solutions and embodiments of the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0020] Figure 1 1H NMR spectrum of the polymer (Sample 1) prepared in Example 1 of the present invention 1 1H NMR diagram;

[0021] Figure 2 13C NMR spectrum of the polymer (Sample 1) prepared in Example 1 13 13C NMR diagram. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Example 1:

[0023] In an anhydrous and oxygen-free environment, in a 50 mL high-pressure reactor, 13.2 g (0.3 mol) of ethylene oxide, 0.0523 g (0.00016 mol) of tetrabutylammonium bromide, 300 μL (1 mol / L, 0.0003 mol) of triethylborane solution, and 178 μL (0.002 mol) of 1,4-butanediol were added successively. Then, 2.5 MPa of carbon dioxide was charged, and the reaction was carried out at 40 °C for 36 h. After the reaction, the unreacted monomers and catalysts were washed away with deionized water, and this sample was named Sample 1. The amount of 1,4-butanediol was changed, and its dosage gradients were set as 267 μL (0.003 mol), 356 μL (0.004 mol), 445 μL (0.005 mol), 534 μL (0.006 mol), 623 μL (0.007 mol), and 712 μL (0.008 mol) respectively, with the other reaction conditions remaining unchanged. The resulting polymers were named Sample 2, Sample 3, Sample 4, Sample 5, Sample 6, and Sample 7 in sequence. Finally, all the polymers in this group were vacuum-dried and then subjected to molecular weight testing, nuclear magnetic resonance analysis, hydroxyl value measurement, and thermal performance analysis. The specific data are listed in Table 1.

[0024] Table 1. Composition, glass transition temperature, and thermal decomposition temperature of aliphatic polycarbonate diols with different molecular weights

[0025]

[0026]

[0027] Example 2:

[0028] In an anhydrous and oxygen-free environment, in a 50 mL high-pressure reactor, 26.4 g (0.6 mol) of ethylene oxide, 0.0451 g (0.00016 mol) of tetrabutylammonium chloride, 300 μL (0.0003 mol) of triethylborane solution, and 356 μL (0.004 mol) of 1,4-butanediol were added successively. Then, 3.0 MPa of carbon dioxide was charged, and the reaction was carried out at 50 °C for 12 h. After the reaction, the unreacted monomers and catalysts were removed by washing with deionized water, and this polymer was named Sample I. The reaction pressure was changed, and the pressure gradients were set as 0.1 MPa, 0.4 MPa, 0.7 MPa, 1.0 MPa, 1.4 MPa, 1.8 MPa, 2.2 MPa, and 2.6 MPa respectively, with the other reaction conditions remaining unchanged. The resulting polymer samples were named Sample A, Sample B, Sample C, Sample D, Sample E, Sample F, Sample G, and Sample H in sequence. Finally, all the polymers in this group were vacuum-dried and then subjected to molecular weight testing, nuclear magnetic resonance analysis, room-temperature water solubility analysis, and thermal performance analysis. The specific data are listed in Table 2. Table 2. Water solubility, composition, glass transition temperature, and thermal decomposition temperature of aliphatic polycarbonate diols at room temperature and atmospheric pressure

[0029]

[0030]

[0031] Example 3:

[0032] In an anhydrous and anaerobic environment, in a 50 mL high-pressure reactor, 13.2 g (0.3 mol) of ethylene oxide, 0.0523 g (0.00016 mol) of tetrabutylammonium bromide, 300 μL (1 mol / L, 0.0003 mol) of triethylboron solution, and 110 μL (0.0015 mol) of propylene glycol were added in sequence. 2.3 MPa of carbon dioxide was charged, and the reaction was carried out at 40 °C for 24 h. After the reaction, the unreacted monomers and catalysts were washed off with deionized water, and this sample was named Sample 8. The amount of propylene glycol was changed, and its dosage gradient was set to 220 μL (0.003 mol), 330 μL (0.0045 mol), 440 μL (0.006 mol), and 550 μL (0.0075 mol) respectively, and the other reaction conditions remained unchanged. The resulting polymers were named Sample 9, Sample 10, Sample 11, and Sample 12 in sequence. Finally, all the polymers in this group were vacuum dried and then subjected to molecular weight testing, nuclear magnetic resonance analysis, hydroxyl value, and thermal performance analysis. The specific data are listed in Table 3.

[0033] Table 3. Composition, glass transition temperature, and thermal decomposition temperature of aliphatic polycarbonate diols obtained using propylene glycol as the raw material

[0034]

[0035]

[0036] Example 4:

[0037] In an anhydrous and anaerobic environment, in a 50 mL high-pressure reactor, 26.4 g (0.6 mol) of ethylene oxide, 0.0677 g (0.00024 mol) of tetrabutylammonium chloride, 300 μL (0.0003 mol) of triethylboron solution, and 330 μL (0.0045 mol) of propylene glycol were added in sequence. 3.0 MPa of carbon dioxide was charged, and the reaction was carried out at 43 °C for 12 h. After the reaction, the unreacted monomers and catalysts were removed by washing with deionized water, and this polymer was named Sample R. The reaction pressure was changed, and the pressure gradients were set to 0.1 MPa, 0.4 MPa, 0.7 MPa, 1.0 MPa, 1.4 MPa, 1.8 MPa, 2.2 MPa, and 2.6 MPa respectively, and the other reaction conditions remained unchanged. The resulting polymer samples were named Sample J, Sample K, Sample L, Sample M, Sample N, Sample O, Sample P, and Sample Q in sequence. Finally, all the polymers in this group were vacuum dried and then subjected to molecular weight testing, nuclear magnetic resonance analysis, room temperature water solubility analysis, and thermal performance analysis. The specific data are listed in Table 4.

[0038] Table 4. Water solubility, composition, glass transition temperature and thermal decomposition temperature of aliphatic polycarbonate diols obtained using propylene glycol as raw material under room temperature and atmospheric pressure

[0039]

[0040]

[0041] Example 5:

[0042] In an anhydrous and anaerobic environment, 26.4 g (0.6 mol) of ethylene oxide, 0.0451 g (0.00016 mol) of tetrabutylammonium chloride, 500 μL (0.0005 mol) of triethylboron solution, and 434 μL (0.005 mol) of resorcinol were successively added to a 50 mL high-pressure reactor. 3.0 MPa of carbon dioxide was charged, and the reaction was carried out at 55 °C for 36 h. After the reaction, unreacted monomers and catalysts were removed by washing with deionized water. This polymer was named sample X. By changing the reaction pressure, pressure gradients of 0.1 MPa, 0.7 MPa, 1.5 MPa, 2.0 MPa, and 2.5 MPa were set respectively, and the other reaction conditions remained unchanged. The obtained polymer samples were successively named sample S, sample T, sample U, sample V, and sample W. Finally, all the polymers in this group were vacuum dried and then subjected to molecular weight testing, NMR analysis, room temperature water solubility analysis, and thermal property analysis. The specific data are listed in Table 5. Table 5. Water solubility, composition, glass transition temperature and thermal decomposition temperature of aliphatic polycarbonate diols obtained using resorcinol as raw material under room temperature and atmospheric pressure

[0043]

[0044]

[0045] In all tables, PEC% is the molar percentage of aliphatic polycarbonate units obtained by copolymerization of ethylene oxide and carbon dioxide; PEO% is the molar percentage of polyether units obtained by homopolymerization of epoxy monomers.

[0046] Explanation of the water solubility of aliphatic polycarbonate diols: In the present invention, ethylene oxide is used as the monomer. Compared with the system using propylene oxide as the monomer, ethylene oxide is the simplest epoxy monomer without any extra methyl or methylene groups, and its reaction activity is very high. Therefore, it is difficult to control the reaction conditions. The present invention has first and independently explored the reaction conditions and obtained this aliphatic polycarbonate diol with a polycarbonate content of 3% - 95%. Since this diol has the least number of methylene groups in the polymer chain compared with other aliphatic polycarbonate diols, does not contain any hydrophobic methyl groups, and has a relatively high oxygen atom content, it is easy to form hydrogen bonds with water molecules, thus possessing water solubility, and the level of water solubility is controlled by its polycarbonate and polyether contents.

[0047] The molecular weight of the water-soluble aliphatic polycarbonate diol and the main influencing factors of the polycarbonate content are respectively the amount of chain transfer agent and the carbon dioxide pressure of the reaction, and the two factors do not affect each other.

Claims

1. A preparation method of a water-soluble aliphatic polycarbonate diol, characterized in that It includes the following steps: Add ethylene oxide, a non-metallic catalyst and a chain transfer agent into a high-pressure reactor, introduce carbon dioxide, and carry out a ring-opening polymerization reaction to obtain a water-soluble aliphatic polycarbonate diol; the structural formula of the water-soluble aliphatic polycarbonate diol is shown as the following formula 1: a = 1 - 60, b = 1 - 20, c = 1 - 70, and a, b, and c are all integers; 2. The preparation method of the water-soluble aliphatic polycarbonate diol according to claim 1, characterized in that The chain transfer agent is ethylene glycol, propylene glycol, tripropylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, cyclohexanedimethanol, hydroquinone or resorcinol.

3. The preparation method of the water-soluble aliphatic polycarbonate diol according to claim 1, characterized in that The molar ratio of the ethylene oxide to the chain transfer agent is 100 - 200:

1.

4. The preparation method of the water-soluble aliphatic polycarbonate diol according to claim 1, characterized in that The pressure of the carbon dioxide is 0.1 - 3 Mpa.

5. The preparation method of the water-soluble aliphatic polycarbonate diol according to claim 1, characterized in that The reaction temperature is 40 - 55 °C, and the reaction time is 12 - 36 h.

6. The preparation method of the water-soluble aliphatic polycarbonate diol according to claim 1, characterized in that The non-metallic catalyst is a Lewis acid-base pair composite catalyst; the Lewis acid is an organoboron compound; the Lewis base is an organic amine salt, and the molar ratio of the Lewis acid to the Lewis base is 3 - 8:0.8; the molar ratio of the ethylene oxide to the Lewis base is 1500 - 3000:0.

8.

7. The preparation method of the water-soluble aliphatic polycarbonate diol according to claim 6, characterized in that The organoboron compound is triethylboron; the organic amine salts are tetra-n-butylammonium chloride and tetra-n-butylammonium bromide.

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