A continuous ring-opening polymerization process based on a mixture of cyclic and linear species and applications thereof

Abstract

The application discloses a continuous ring-opening polymerization method based on a mixture of a ring body and a linear body and application, wherein the steps of the continuous ring-opening polymerization method comprise the following steps: S1, dissolving the mixture of the ring body and the linear body in a solvent, heating to 90-110 DEG C to form a homogeneous solution; S2, adding an organic base catalyst and a single-end capped molecular weight regulator to the homogeneous solution and stirring uniformly, and then reacting under a negative pressure condition for 2-5 h to obtain polysiloxane; wherein the organic base catalyst is a supported phosphazene base; the amount of the organic base catalyst is 0.0014-0.025% of the total mass of the mixture of the linear body and the ring body; and the amount of the single-end capped molecular weight regulator is 0.2-5% of the total mass of the mixture of the linear body and the ring body. The method synchronously catalyzes ring-opening of the ring body and polycondensation of the linear body through the supported phosphazene base, realizes efficient preparation of high-molecular-weight polysiloxane (ring body residue is less than or equal to 0.01%), and significantly reduces energy consumption, raw material cost and waste emission; the obtained product has controllable molecular weight and excellent performance, and is suitable for application fields such as silicone rubber.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon material synthesis, and particularly relates to a continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers and its application. Background Technology

[0002] Organosilicon compounds are widely used in many industrial fields due to their excellent temperature resistance, insulation, and chemical stability, especially in the electronics, automotive, and construction industries, where the demand for organosilicon materials is increasing. Dimethylchlorosilane is one of the important raw materials for organosilicon materials. Its hydrolysis products are usually a mixture of cyclic (such as D4, D5, etc.) and linear products. However, the cyclic products can pose potential hazards to the environment and human health, so effective treatment methods are needed to reduce their adverse effects.

[0003] Currently, the main industrial method for separating cyclic and linear products is high-temperature heating (180~240℃) combined with negative pressure conditions. In this process, the cyclic product is vaporized and condensed for recovery, while the linear product remains in the liquid phase. This method can achieve a certain degree of separation, but it also has significant drawbacks: First, high-temperature operation leads to high energy consumption and increased production costs; second, high temperature control precision is required, and fluctuations can easily affect separation efficiency and product purity; in addition, the separated cyclic product still needs to undergo a complex ring-opening reaction before it can be used, and the whole process is time-consuming and inefficient.

[0004] Therefore, there is an urgent need for a continuous ring-opening polymerization method and its application based on a mixture of cyclic and linear polymers to address the shortcomings of existing technologies. Summary of the Invention

[0005] In view of the above problems, the purpose of this invention is to provide a continuous ring-opening polymerization method and its application based on a mixture of cyclic and linear polymers. This method simultaneously catalyzes the ring-opening of the cyclic polymer and the polycondensation of the linear polymer using a supported phosphazene base. While achieving efficient preparation of high molecular weight polysiloxanes (cyclic residue ≤0.01%), it eliminates the traditional separation and neutralization steps, significantly reducing energy consumption, raw material costs and waste emissions. The resulting product has a controllable molecular weight and excellent performance, and is suitable for applications such as silicone rubber.

[0006] To achieve the above objectives, the first aspect of the present invention provides a continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers, comprising the following steps: S1. Dissolve the mixture of cyclic and linear forms in a solvent and heat to 90~110℃ to form a homogeneous solution; S2. Add an organic base catalyst and a single-terminated molecular weight regulator to the homogeneous solution and stir until homogeneous. Then react under negative pressure for 2-5 hours. After the reaction is complete, remove the solvent to obtain polysiloxane. The organic base catalyst is a supported phosphazene base, and the amount of organic base catalyst is 0.0014-0.025% of the total mass of the linear and cyclic mixture. The amount of single-terminated molecular weight regulator is 0.2-5% of the total mass of the linear and cyclic mixture.

[0007] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses a mixture of cyclic and linear forms of dimethylchlorosilane after hydrolysis as raw material. A supported phosphazene base is used to simultaneously achieve ring-opening of the cyclic form and dehydration polymerization of the linear form, converting the raw material into a high molecular weight polysiloxane. This process not only improves raw material utilization but also significantly reduces cyclic residue (residual amount ≤0.01%), thereby reducing energy consumption and improving the environmental friendliness and safety of the product. Simultaneously, the added molecular weight regulator ensures controllable polymer molecular weight, resulting in a polysiloxane with excellent overall performance, suitable for applications in fields such as silicone rubber.

[0008] 2. This invention uses a mixture of cyclic and linear forms of dimethylchlorosilane after hydrolysis as raw material and directly catalytically catalyzes ring-opening to prepare polysiloxane, eliminating the energy-intensive separation step and significantly reducing raw material costs.

[0009] 3. This invention uses supported phosphazene base, which realizes dynamic release-absorption of catalyst, avoiding the neutralization and filtration steps of the traditional KOH method and the heating and catalyst destruction steps of tetramethylammonium hydroxide. The catalyst can be reused, further reducing production costs and waste emissions.

[0010] Furthermore, the mass ratio of the cyclic body to the mixture of the cyclic body and the linear body in the present invention is 5-95%. For example, the mass ratio of the cyclic body to the mixture of the cyclic body and the linear body can be, but is not limited to, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 95%.

[0011] Furthermore, the solvent in step S1 of this invention is n-octane, which has good solubility and can effectively dissolve cyclic compounds (such as D4, D5, etc.) and linear compounds (such as α,ω-dihydroxypolydimethylsiloxane). It also has a boiling point of 125.6~126.0°C, which is suitable for a reaction temperature range of 90~110°C and facilitates subsequent vacuum distillation for removal. Of course, the type of solvent is not limited to n-octane; other organic solvents capable of dissolving mixtures of cyclic and linear compounds can also be used in this invention, such as: alkanes (e.g., n-hexane, n-heptane, cyclohexane, etc.); aromatics (e.g., toluene, xylene, ethylbenzene, etc.); and ethers (e.g., tetrahydrofuran (THF), etc.). The selection of these solvents requires comprehensive consideration of solubility, boiling point, reaction stability, and ease of subsequent removal.

[0012] Furthermore, the heating temperature in step S1 of the present invention may be, but is not limited to, 90°C, 95°C, 98°C, 102°C, 107°C, or 110°C.

[0013] Furthermore, the cyclic body of the present invention is mainly composed of octamethylcyclotetrasiloxane (D4), the content of which is not less than 50% of the total mass of the cyclic body; the remaining components are selected from at least one of hexamethylcyclotrisiloxane (D3), decamethylcyclopentasiloxane (D5), dodecylcyclohexasiloxane (D6), tetradecylcycloheptasiloxane (D7), hexadecylcyclooctasiloxane (D8), octadecylcyclononasiloxane (D9) and icosylcyclodecasiloxane (D10).

[0014] Furthermore, the linear viscosity of the present invention is 65~150 cs. For example, the linear viscosity may be, but is not limited to, 65 cs, 75 cs, 95 cs, 105 cs, 125 cs, 135 cs, 145 cs, or 150 cs.

[0015] Furthermore, the preparation of the supported phosphazene base of the present invention includes: loading the phosphazene base onto a porous adsorbent and coating it with a coating agent. The organic base catalyst is formed by loading the phosphazene base onto a porous adsorbent and then coating it with a coating agent to form stable supported phosphazene base particles. During the reaction in step S2, the high temperature of 90-110°C increases the solubility of the phosphazene base in the reaction system, resulting in a certain degree of desorption. Therefore, the adsorbed base and the desorbed base catalyze the reaction simultaneously, improving catalytic efficiency, reducing side reactions, and ensuring that the final polysiloxane product contains no rings or has a very low ring content (≤0.01%). After the reaction is complete and the temperature decreases, due to the polar adsorption effect, the supported phosphazene base particles can re-adsorb the free phosphazene base, allowing the catalyst to be reused. Therefore, by using a supported phosphazene base, the simultaneous ring-opening polymerization and linear polycondensation can be effectively promoted, which is beneficial for maintaining the stability of the overall system during ring-opening and polymerization.

[0016] Furthermore, the supported phosphazene base of the present invention comprises, by mass, 20-30 parts of porous adsorbent, 1-8 parts of coating agent, and 40-55 parts of phosphazene base. Therefore, the highest concentration of phosphazene base is 55 / (55+20+1)×100%=72.4%; the lowest concentration is 40 / (40+8+30)×100%=51.3%, meaning that a mass concentration range of 51.3-72.4% for the phosphazene base ensures that it exhibits excellent catalytic activity.

[0017] Further, the mass fraction of the porous adsorbent of the present invention can be, but is not limited to, 20 parts, 22 parts, 25 parts, 28 parts, or 30 parts. Specifically, the porous adsorbent of the present invention is selected from at least one of hollow silica, expanded graphite, and diatomaceous earth. Hollow silica, expanded graphite, and diatomaceous earth all have porous structures, which facilitate the adsorption of diluted phosphazene alkali. Preferably, the porous adsorbent is a mixture of hollow silica, expanded graphite, and diatomaceous earth; more specifically, the mass ratio of hollow silica, expanded graphite, and diatomaceous earth is 1:0.3:0.1.

[0018] Furthermore, the mass fraction of the coating agent of the present invention may be, but is not limited to, 1 part, 2 parts, 5 parts, 6 parts, or 8 parts. Specifically, the coating agent is prepared by uniformly mixing polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone. More specifically, the mass ratio of polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone is 1:0~1:0.5~1.5; for example, the mass ratio of the three can be, but is not limited to, 1:0.5:1, 1:0.7:1.2, or 1:0.8:1.5. This coating agent has good adhesion and can easily form a coating film on the surface of a porous adsorbent that adsorbs phosphazene base. This allows the organic base catalyst to release phosphazene base when heated and maintain stable continuous polymerization in the overall system, so that the cyclic (D4~D10) content in the final polysiloxane product is less than 0.01%.

[0019] Further, the mass fraction of the phosphazene base of the present invention may be, but is not limited to, 40 parts, 42 parts, 44 parts, 47 parts, 49 parts, 52 parts, or 55 parts. Specifically, the phosphazene base is selected from at least one of the following: phosphazene ligand P4-tert-butyl (P4-T-BU), cyclotriphosphazene base (CTPB), 2,4,6-tris[tris(dimethylamino)phosphoniumimide]-1,3,5-triazine (C3N3-Me-P3), and 2,4,6-tris[tris(1-pyrrolidinyl)phosphoniumimide]-1,3,5-triazine (C3N3-Py-P3). It should be noted that the scope of phosphazene bases involved in the present invention is not limited to these few, but also includes other derivatives or similar structures not explicitly listed. More specifically, P4-T-BU (CAS: 111324-04-0), CTPB, C3N3-Me-P 3、 The structural formula of C3N3-Py-P3 is shown below:

[0020] Furthermore, the negative pressure in step S2 of the present invention is 70~75 mmHg. Specifically, maintaining the negative pressure can remove the water produced in the reaction process.

[0021] Furthermore, the preparation of the organic base catalyst of the present invention includes: (1) Diluent is divided into a first diluent and a second diluent, and the coating agent is added to the first diluent to obtain diluent A; and phosphazene base is diluted in the second diluent to obtain diluent B; (2) Mix diluent B with porous adsorbent to obtain adsorbent C; (3) After mixing the diluted solution A and the adsorbent C evenly, heat and reflux, and then successively perform vacuum distillation, drying and pulverization to obtain the organic base catalyst.

[0022] The organic base catalyst (supported phosphazene base) of this invention maintains long-term stability in cyclic systems of different concentrations, thereby achieving continuous and controllable release of phosphazene base, ensuring the stability of the ring-opening polymerization process, and ensuring that the residual amount of cyclic compounds in the final product is ≤0.01% and that the obtained silicone rubber has excellent physical properties. Specifically, by dissolving the coating agent in a first diluent to form diluent A, and dissolving the phosphazene base in a second diluent to obtain diluent B, uniform dispersion of the coating agent and phosphazene base can be ensured, allowing the adsorbent to effectively load the phosphazene base. Then, a stable coating film structure is formed by the coating agent, realizing the slow-release effect of the catalyst. This not only avoids the residue of unopened ring compounds in the product, but also promotes further reaction between the cyclic compounds and linear compounds to generate low molecular weight polysiloxanes, thereby significantly improving the overall performance of the material.

[0023] Further, step (1) of the present invention includes dividing the diluent into equal amounts of a first diluent and a second diluent.

[0024] Furthermore, the drying conditions in step (3) of the present invention are: drying at 45~55°C for 1.5~2.5h.

[0025] Furthermore, in step (3) of the present invention, the heating and reflux time is 5-7 hours.

[0026] Further, the mass fraction of the diluent of the present invention is 7 to 39 parts; for example, the mass fraction of the diluent may be, but is not limited to, 7 parts, 10 parts, 15 parts, 20 parts, 28 parts, 33 parts, or 39 parts. Specifically, the diluent may be, but is not limited to, ethyl acetate.

[0027] Furthermore, the single-terminated molecular weight regulator of the present invention is at least one selected from trimethylsiloxy-terminated polydimethylsiloxane hydride, trimethylsiloxy-terminated polydimethylsiloxane alkane, vinyldimethylsiloxy-terminated polydimethylsiloxane hydride, and vinyldimethylsiloxy-terminated polydimethylsiloxane alkane. The structural formula of trimethylsiloxy-terminated polydimethylsiloxane hydride is (CH3)3SiO((CH3)2SiO). n H, n is 0~20; the structural formula of trimethylsiloxy-terminated polydimethylsiloxane alkane is (CH3)3SiO((CH3)2SiO). n (CH2) m CH3, n is 0~20, m is 0~3; the structural formula of vinyl dimethylsiloxy-terminated polydimethylsiloxane hydride is CH2=CH(CH3)2SiO((CH3)2SiO) n H, n is 0~20; the structural formula of vinyl dimethylsiloxy-terminated polydimethylsiloxane alkane is CH2=CH(CH3)2SiO((CH3)2SiO). n (CH2) m CH3, n is 0~20, m is 0~3.

[0028] Accordingly, a second aspect of the present invention also provides the application of the polysiloxane prepared by the aforementioned continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers in silicone rubber materials. Detailed Implementation

[0029] To better illustrate the purpose, technical solution, and beneficial effects of this invention, the invention will be further described below with reference to specific embodiments. It should be noted that the methods described below are further explanations of this invention and should not be construed as limiting it.

[0030] Details of the main raw materials used in the following embodiments and comparative examples are shown below: The ring is a mixture of D4 (60%), D5 (35%), and D6 (5%). The linear form is α,ω-dihydroxypolydimethylsiloxane with a viscosity of 100 cs; Hollow silica was purchased from Beijing Zhongke Keyou Nanotechnology Co., Ltd., which has a pore size of 3nm and a particle size of 100nm. The expanded graphite is 200-300 mesh and was purchased from Qingdao Mingrun Chenyue Graphite Co., Ltd. The diatomaceous earth is 325-600 mesh and was purchased from Shijiazhuang Huabang Mineral Products Co., Ltd. The average molecular weight of polyethylene glycol is 1000; The triblock copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide has CAS number 9003-11-6, average molecular weight of 4400, 30% polyethylene oxide content, and was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The average molecular weight of liquid carboxyl-terminated polycaprolactone is 1000. The phosphazene base is P4-T-BU, and its CAS number is 111324-04-0.

[0031] Example 1-1 This embodiment provides an organic base catalyst, which is a supported phosphazene base, and its preparation includes: (1) Divide 24 parts by mass of diluent into 12 parts by mass of first diluent and 12 parts by mass of second diluent, and add 1 part by mass of coating agent diluent to the first diluent to obtain diluent A; and dilute 55 parts by mass of phosphazene base to the second diluent to obtain diluent B; (2) Mix diluent B with 20 parts by mass of porous adsorbent to obtain adsorbent C; (3) After mixing the diluent A with the adsorbent C evenly, heat under reflux for 6 hours, then remove the diluent by vacuum distillation, and then dry in an oven at 50°C for 2 hours. After pulverizing, the organic base catalyst is obtained. The diluent is ethyl acetate; the porous adsorbent is hollow silica; and the coating agent is obtained by uniformly mixing polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone in a weight ratio of 1:0.5:1.125.

[0032] Examples 1-2 This embodiment provides an organic base catalyst, which is a supported phosphazene base, and its preparation includes: (1) Divide 21.7 parts by mass of diluent into 10.85 parts by mass of first diluent and 10.85 parts by mass of second diluent, and add 5.3 parts by mass of coating agent diluent to the first diluent to obtain diluent A; and dilute 43 parts by mass of phosphazene base to the second diluent to obtain diluent B; (2) Mix diluent B with 25 parts by mass of porous adsorbent to obtain adsorbent C; (3) After mixing the diluent A with the adsorbent C evenly, heat under reflux for 6 hours, then remove the diluent by vacuum distillation, and then dry in an oven at 50°C for 2 hours. After pulverizing, the organic base catalyst is obtained. The diluent is ethyl acetate; the porous adsorbent is hollow silica; and the coating agent is obtained by uniformly mixing polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone in a weight ratio of 1:0.5:1.125.

[0033] Examples 1-3 This embodiment provides an organic base catalyst, which is a supported phosphazene base, and its preparation includes: (1) Divide 22 parts by mass of diluent into 11 parts by mass of first diluent and 11 parts by mass of second diluent, and add 8 parts by mass of coating agent diluent to the first diluent to obtain diluent A; and dilute 40 parts by mass of phosphazene base to the second diluent to obtain diluent B; (2) Mix diluent B with 30 parts by mass of porous adsorbent to obtain adsorbent C; (3) After mixing the diluent A with the adsorbent C evenly, heat under reflux for 6 hours, then remove the diluent by vacuum distillation, and then dry in an oven at 50°C for 2 hours. After pulverizing, the organic base catalyst is obtained. The diluent is ethyl acetate; the porous adsorbent is hollow silica; and the coating agent is obtained by uniformly mixing polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone in a weight ratio of 1:0.5:1.125.

[0034] Examples 1-4 Examples 1-4 are basically the same as Examples 1-2, the only difference being that the porous adsorbent in Examples 1-4 is expanded graphite.

[0035] Examples 1-5 Examples 1-5 are basically the same as Examples 1-2, the only difference being that the porous adsorbent in Examples 1-5 is diatomaceous earth.

[0036] Examples 1-6 Examples 1-6 are basically the same as Examples 1-2, except that the porous adsorbent in Examples 1-6 is composed of hollow silica, expanded graphite and diatomaceous earth in a weight ratio of 1:0.3:0.1.

[0037] Comparative Example 1-1 Comparative Example 1-1 and Example 1-2 are basically the same, except that the coating agent in Example 1-2 is replaced with an equal amount of porous adsorbent.

[0038] Comparative Examples 1-2 Comparative Examples 1-2 and Examples 1-2 are basically the same, except that the liquid carboxyl-terminated polycaprolactone in Examples 1-2 is replaced with polyethylene glycol in equal amounts.

[0039] Example 1 This embodiment provides a continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers, the steps of which include: S1. Dissolve the mixture of cyclic and linear molecules in a solvent and heat to 100°C to form a homogeneous solution; S2. Add the organic base catalyst and single-end molecular weight regulator prepared in Example 1-1 to the homogeneous solution and stir until uniform. Then react for 3.5 h under a negative pressure of 75 mmHg. After the reaction is completed, remove the solvent to obtain polysiloxane. The amount of organic base catalyst used is 0.02% of the total mass of the linear and cyclic mixture, and the amount of single-terminated molecular weight regulator used is 1% of the total mass of the linear and cyclic mixture; the single-terminated molecular weight regulator is CH2=CH(CH3)2SiO((CH3)2SiO). 10 H; the solvent is n-octane.

[0040] Example 2 Example 2 is basically the same as Example 1, except that the organic base catalyst in Example 2 is the same as the organic base catalyst prepared in Example 1-2.

[0041] Example 3 Example 3 is basically the same as Example 1, except that the organic base catalyst in Example 3 is the same as the organic base catalyst prepared in Examples 1-3.

[0042] Example 4 Example 4 is basically the same as Example 1, except that the organic base catalyst in Example 4 is the same as the organic base catalyst prepared in Examples 1-4.

[0043] Example 5 Example 5 is basically the same as Example 1, except that the organic base catalyst in Example 5 is the same as the organic base catalyst prepared in Examples 1-5.

[0044] Example 6 Example 6 is basically the same as Example 1, except that the organic base catalyst in Example 6 is the same as the organic base catalyst prepared in Examples 1-6.

[0045] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, except that the organic base catalyst in Comparative Example 1 is the organic base catalyst prepared in Comparative Example 1-1.

[0046] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that the organic base catalyst in Comparative Example 2 is the same as the organic base catalyst prepared in Comparative Examples 1-2.

[0047] Comparative Example 3 This comparative example provides a continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers, the steps of which include: S1. Dissolve the mixture of cyclic and linear molecules in a solvent and heat to 100°C to form a homogeneous solution; S2. Add phosphazene base and single-end molecular weight regulator to the homogeneous solution and stir until uniform. Then react under a negative pressure of 75 mmHg for 2 hours. After the reaction is completed, remove the solvent to obtain polysiloxane. The amount of phosphazene base used is 0.014% of the total mass of the linear and cyclic mixture, and the amount of the single-terminated molecular weight regulator used is 5% of the total mass of the linear and cyclic mixture; the single-terminated molecular weight regulator is (CH3)3SiO ((CH3)2SiO). 10 H; the solvent is n-octane.

[0048] Comparative Example 4 This comparative example provides a continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers, the steps of which include: S1. Dissolve the mixture of cyclic and linear molecules in a solvent and heat to 100°C to form a homogeneous solution; S2. Add phosphazene base and single-end molecular weight regulator to the homogeneous solution and stir until homogeneous. Then react under a negative pressure of 75 mmHg for 3.5 h. After the reaction is completed, remove the solvent to obtain polysiloxane. The amount of phosphazene base used is 0.014% of the total mass of the linear and cyclic mixture, and the amount of the single-terminated molecular weight regulator used is 1% of the total mass of the linear and cyclic mixture; the single-terminated molecular weight regulator is (CH3)3SiO ((CH3)2SiO). 10 H; the solvent is n-octane.

[0049] Comparative Example 5 This comparative example provides a continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers, the steps of which include: S1. Dissolve the mixture of cyclic and linear molecules in a solvent and heat to 110°C to form a homogeneous solution; S2. Add phosphazene base and single-end molecular weight regulator to the homogeneous solution and stir until uniform. Then react for 3 hours under a negative pressure of 75 mmHg. After the reaction is completed, remove the solvent to obtain polysiloxane. The amount of phosphazene base used was 0.00175% of the total mass of the linear and cyclic mixture, and the amount of the single-terminated molecular weight regulator was 0.2% of the total mass of the linear and cyclic mixture; the single-terminated molecular weight regulator was (CH3)3SiO ((CH3)2SiO). 10 H; the solvent is n-octane.

[0050] Comparative Example 6 Comparative Example 6 is basically the same as Comparative Example 4, except that the single-terminal molecular weight regulator in Comparative Example 6 is (CH3)3SiO ((CH3)2SiO). 10 (CH2)2CH3.

[0051] Comparative Example 7 Comparative Example 7 is basically the same as Comparative Example 4, except that the single-end molecular weight regulator in Comparative Example 7 is CH2=CH(CH3)2SiO((CH3)2SiO). 10 H.

[0052] Comparative Example 8 Comparative Example 8 is basically the same as Comparative Example 4, except that the single-end molecular weight regulator in Comparative Example 8 is CH2=CH(CH3)2SiO((CH3)2SiO). 10 (CH2)2CH3.

[0053] Comparative Example 9 Comparative Example 9 is basically the same as Comparative Example 4, except that: S1, the mixture of cyclic and linear isotopes is dissolved in a solvent and heated to 80°C to form a homogeneous solution.

[0054] Comparative Example 10 Comparative Example 10 is basically the same as Comparative Example 4, except that the phosphazene base in Comparative Example 4 is replaced with an equal amount of KOH catalyst.

[0055] By adjusting the feeding ratio of cyclic to linear polymers, three mixtures of cyclic and linear polymers with different ratios were prepared: Low cyclic content group: 30wt% cyclic compound + 70wt% linear compound (Experiment 1) Medium cyclic content group: 60wt% cyclic body + 40wt% linear body (Experiment 2) High cyclic content group: 80wt% cyclic compounds + 20wt% linear compounds (Experiment 3) Then, using the three sets of cyclic and linear mixtures with different ratios as raw materials, polysiloxanes were prepared by continuous ring-opening polymerization methods based on cyclic and linear mixtures as described in Examples 1-6 and Comparative Examples 1-10, respectively.

[0056] The residual amount of cyclic compounds in the prepared polysiloxane was determined by gas chromatography (GC); wherein, grade I: cyclic compound content less than 0.01%, grade II: cyclic compound content 0.01~0.50%, grade III: cyclic compound content 0.51~1.00%, grade IV: cyclic compound content 1.10~5%, and grade V: cyclic compound content greater than 5%.

[0057] Table 1 Cyclic Residue of Polysiloxane

[0058] As shown in Table 1, the cyclic content in Examples 1-6 is less than 0.01%, indicating that regardless of whether the raw material has a high or low cyclic content, the continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers of the present invention can significantly reduce the residual cyclic content in polysiloxanes (residual amount ≤0.01%). This is because the organic base catalyst (supported phosphazene base) of the present invention can remain stable for a long time in cyclic systems of different concentrations, thereby achieving continuous and controllable release of phosphazene base, ensuring the stability of the ring-opening polymerization process, and making the residual cyclic content in the final product ≤0.01% and the obtained silicone rubber has excellent physical properties.

[0059] As shown in Table 1, when the cyclic content in the raw material is high, the continuous ring-opening polymerization method of Comparative Example 1 cannot significantly reduce the residual cyclic content in polysiloxane. This indicates that removing the coating agent will affect the adsorption of phosphazene base on the surface of the porous adsorbent, thus affecting the stability of the ring-opening polymerization process.

[0060] As shown in Table 1, when the cyclic content in the raw materials is high, the continuous ring-opening polymerization method of Comparative Example 2 cannot significantly reduce the residual cyclic content in polysiloxanes. This is because the carboxyl-terminated polycaprolactone reacts with polyethylene glycol and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer to form a polymer on the catalyst surface, which plays a coating role. Therefore, if polyethylene glycol is removed, the chain will not extend, the polymer molecular weight will be relatively small, and it will be easy to dissolve into the system, resulting in an unsatisfactory coating effect.

[0061] As shown in Table 1, when the cyclic content in the raw materials is high or moderate, the continuous ring-opening polymerization method of Comparative Examples 3-8 cannot significantly reduce the residual cyclic content in polysiloxanes. This may be because, compared with phosphazene base, the present invention uses a porous adsorbent to load phosphazene base and then coats it with a coating agent to form stable supported phosphazene base particles. The supported phosphazene base has a better slow-release effect, thereby maintaining the stability of the entire ring-opening and polymerization process and reducing the cyclic content in the final product.

[0062] As shown in Table 1, even when the cyclic content in the raw materials is very low, the continuous ring-opening polymerization method of Comparative Example 9 cannot significantly reduce the residual cyclic content in polysiloxane at low temperatures. This indicates that dissolving the mixture of cyclic and linear molecules in a solvent and forming a homogeneous solution at 90-110°C is beneficial to maintaining the stability of the overall system during ring-opening and polymerization.

[0063] As shown in Table 1, even when the cyclic content in the raw materials is very low, the continuous ring-opening polymerization method of Comparative Example 10 cannot significantly reduce the residual cyclic content in polysiloxanes. This indicates that compared with the traditional KOH method, the use of supported phosphazene base can achieve a better slow-release effect, thereby maintaining the stability of the entire ring-opening and polymerization process and reducing the cyclic content in the final product.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers, characterized in that the steps include... include: S1. Dissolve the mixture of cyclic and linear molecules in a solvent and heat to 90~110℃ to form a homogeneous solution; S2. Add an organic base catalyst and a single-terminated molecular weight regulator to the homogeneous solution and stir until homogeneous. Then react under negative pressure for 2-5 hours. After the reaction is complete, remove the solvent to obtain polysiloxane. The organic base catalyst is a supported phosphazene base; the amount of the organic base catalyst is 0.0014~0.025% of the total mass of the cyclic and linear mixture, and the amount of the single-terminated molecular weight regulator is 0.2~5% of the total mass of the cyclic and linear mixture; the preparation of the supported phosphazene base includes: loading the phosphazene base onto a porous adsorbent and coating it with a coating agent; The supported phosphazene base comprises, by mass, 20-30 parts of the porous adsorbent, 1-8 parts of the coating agent, and 40-55 parts of the phosphazene base; the coating agent is prepared by uniformly mixing polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone; the mass ratio of polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and liquid carboxyl-terminated polycaprolactone is 1:0-1:0.5-1.5, and the mass of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is not 0.

2. The continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers as described in claim 1, characterized in that, The mass ratio of the cyclic body to the mixture of the cyclic body and the linear body is 5-95%.

3. The continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers as described in claim 1, characterized in that, The phosphazene base is selected from at least one of the following: phosphazene ligand P4-tert-butyl, cyclotriphosphazene base, 2,4,6-tris[tris(dimethylamino)phosphoniumimide]-1,3,5-triazine, and 2,4,6-tris[tris(1-pyrrolyl)phosphoniumimide]-1,3,5-triazine.

4. The continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers as described in claim 1, characterized in that, The porous adsorbent is selected from at least one of hollow silica, expanded graphite, and diatomaceous earth.

5. The continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers as described in claim 1, characterized in that, The preparation of the organic base catalyst includes: (1) Diluent is divided into a first diluent and a second diluent, and the coating agent is diluted in the first diluent to obtain diluent A; and the phosphazene base is diluted in the second diluent to obtain diluent B; (2) The diluted substance B is mixed evenly with the porous adsorbent to obtain adsorbent C; (3) After the diluted solution A and the adsorbent C are mixed evenly, the mixture is heated under reflux and then subjected to vacuum distillation, drying and pulverization to obtain the organic base catalyst.

6. The continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers as described in claim 1, characterized in that, The single-terminated molecular weight regulator is at least one of trimethylsiloxy-terminated polydimethylsiloxane hydride, trimethylsiloxy-terminated polydimethylsiloxane alkane, vinyldimethylsiloxy-terminated polydimethylsiloxane hydride, and vinyldimethylsiloxy-terminated polydimethylsiloxane alkane.

7. The application of the polysiloxane prepared by the continuous ring-opening polymerization method based on a mixture of cyclic and linear polymers as described in any one of claims 1 to 6 in silicone rubber materials.

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