A method for preparing phenyl silicone rubber raw rubber by one-pot process

Abstract

The application provides a method for preparing phenyl silicone rubber raw rubber by one-pot method, comprising the following steps: (1) adding a siloxane ring body and an end-capping agent to prepare a premix; (2) adding a catalyst to the premix obtained in step (1) to perform a first-stage ring-opening polymerization reaction, and continuously adding a cocatalyst to perform a second-stage ring-opening polymerization reaction; (3) adding a neutralizing agent to the ring-opening polymerization product of step (2) to continuously react to obtain phenyl silicone rubber raw rubber. The ring-opening polymerization reaction is completed in 3-6 hours, further, no gas is released at high temperature, and no adverse effect on the mechanical properties of the silicone rubber is caused. The ring-opening polymerization reaction is carried out by means of drum inert gas and short-range vacuum polymerization technology throughout the whole process, the content of hydroxyl groups can be effectively controlled, and the product distribution width is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of phenyl silicone rubber, and particularly relates to a method for preparing phenyl silicone rubber raw rubber by a one-pot process. Background Art

[0002] Methylvinylphenyl silicone rubber, also known as phenyl silicone rubber, is made by introducing diphenylsiloxane segments (or methylphenylsiloxane segments) into the molecular chain of vinyl silicone rubber. Phenyl silicone rubber exhibits superior resistance to heat, cold, weather, ozone, and radiation. It can be used as a potting and sealing material for space-grade electronic and electrical components, as well as an insulation, moisture-proof, shock-resistant, and high- and low-temperature-resistant potting and packaging material for instruments and meters. It is widely used in cutting-edge fields such as aerospace, nuclear power equipment, and national defense security.

[0003] The preparation methods of phenyl silicone rubber include polymerization and polycondensation. The most common polycondensation method is hydrolysis polycondensation. First, the main products are cyclic siloxane and linear polydimethylsiloxane prepared by hydrolysis of the same or different bifunctional chlorosilanes. Then they are condensed individually or with each other to form Si-O-Si bonds. For example, the copolymerized high-performance damping silicone rubber and its preparation method disclosed in patent CN102181056B are characterized by adding 100 molar parts of octamethylcyclotetrasiloxane, 0.001-1 molar parts of tetramethyltetravinylcyclotetrasiloxane, 1-50 molar parts of octaphenylcyclotetrasiloxane, and 1-500 molar parts of a mixed ring containing methylphenylsiloxane chain segments into a reactor, dehydrating at a temperature of 55-65°C for 1-3 hours under nitrogen protection, and then adding 0.01-100 molar parts of a catalyst. 5wt%, continue bubbling with dry nitrogen, and when the viscosity rises, add 0.00001-1 mmol of end-capping agent, and carry out equilibrium reaction at a temperature of 90-110°C for 7-8h. After the reaction is completed, raise the temperature to 145-165°C and maintain for 1-2h to decompose and destroy the catalyst. Finally, raise the temperature to 180-200°C and remove the low molecular weight products under vacuum at a vacuum degree of 6-12Mpa until there is no distillate. Then, reduce the temperature to room temperature and discharge the material. Stop decompression to obtain polymethylphenylvinylsiloxane.

[0004] The preparation of phenyl silicone rubber by ring-opening polymerization of cyclosiloxane is one of the most widely used polymerization methods in industry and laboratories. Compared with the hydrolysis and condensation method, it can better control the molecular weight by adjusting the stoichiometric ratio of cyclosiloxane and end-capping agent. For example, patent CN101851334B discloses dimethyl diphenyl room temperature vulcanized silicone rubber and its production process and uses. It is characterized by using the following four raw materials for synthesis, and the formula content ratio by weight is as follows: (1) liquid dimethyl diphenyl mixed cyclosiloxane 20.0-34.0%, (2) dimethyl cyclosiloxane 65.58-79.89%, (3) water 0.10-0.40%, and (4) tetramethyl ammonium hydroxide 0.008-0.015%. Phenyl silicone rubber prepared by this ring-opening polymerization method exhibits excellent comprehensive properties, including resistance to high and low temperatures. To shorten the reaction time, tetramethylammonium hydroxide (TMAH), a highly catalytically active agent, is used. However, when high temperatures destroy the catalyst, residual decomposition product trimethylamine is likely to remain in the product, resulting in a strong odor in the raw phenyl rubber. Furthermore, this catalyst has strict requirements for the moisture content of the raw materials. When the moisture exceeds 20 ppm, the catalyst deactivates, which can lead to unstable hydroxyl values ​​during the polymerization process, affecting the mechanical properties of the product. Substituting less active catalysts such as potassium hydroxide, sodium hydroxide, or potassium siloxane oxide generally requires 4-8 hours at higher temperatures to complete the equilibrium reaction, and post-reaction catalyst neutralization is also complex. Therefore, it is necessary to develop a method for preparing phenyl silicone rubber that is odorless, has a low hydroxyl content, and offers a short reaction time without compromising the mechanical properties of the rubber. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a method for preparing phenyl silicone rubber raw rubber by a one-pot process. First, the ring-opening polymerization reaction is divided into an alkali metal silicon alkoxide catalytic reaction stage and an alkali metal silicon alkoxide and a co-catalyst synergistic catalytic reaction stage. The catalyst is not easily deactivated when exposed to water, and the ring-opening polymerization reaction can be completed in 3-6 hours, which is equivalent to the reaction rate under the catalysis of tetramethylammonium hydroxide. Secondly, the co-catalyst does not need to be destroyed by adding additional additives. Once the alkali metal silicon alkoxide loses its activity, the co-catalyst will have no catalytic effect. Moreover, both catalysts do not release gas at high temperatures, and will not have an adverse effect on the mechanical properties of the silicone rubber. Preferably, the ring-opening polymerization reaction is carried out by blowing inert gas throughout the process in combination with short-range vacuum polymerization technology, which can effectively control the hydroxyl content and greatly improve the product distribution width.

[0006] In order to achieve the above objectives, the following technical solutions are adopted:

[0007] The method for preparing phenyl silicone rubber raw rubber by a one-pot process comprises the following steps:

[0008] (1) adding siloxane ring body and end-capping agent to prepare a premix;

[0009] (2) adding a catalyst to the premix obtained in step (1) to carry out a first-stage ring-opening polymerization reaction; and continuing to add a co-catalyst to carry out a second-stage ring-opening polymerization reaction;

[0010] (3) adding a neutralizing agent to the ring-opening polymerization product of step (2), and continuing the reaction to obtain a phenyl silicone rubber raw rubber.

[0011] Preferably, the method specifically includes the following steps:

[0012] (1) adding a siloxane ring body and a capping agent into a reaction kettle, stirring and mixing, heating, vacuum dehydration, and pressure relief to obtain a premix for use;

[0013] (2) introducing an inert gas into the premix of step (1), raising the temperature, adding a catalyst and mixing uniformly, and carrying out a first-stage ring-opening polymerization reaction; adjusting the inert gas flow rate, evacuating the mixture, adding a co-catalyst, and carrying out a second-stage ring-opening polymerization reaction; after the reaction is completed, releasing the pressure at a constant temperature and setting aside;

[0014] (3) adding a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mixing and reacting uniformly, heating and vacuuming after the reaction to obtain phenyl silicone rubber raw rubber.

[0015] The siloxane ring body of step (1) includes 2800 parts by mass of dimethylsiloxane ring body (Me2SiO) m , 0-500 parts by mass of methylphenylsiloxane ring (MePhSiO) n , 0-350 parts by mass of diphenylsiloxane ring (Ph2SiO) a 8-12 parts by mass of methyl vinyl ring (MeViSiO) b , wherein m is an integer of 3-7, n is an integer of 3-5, a is an integer of 3-4, and b is an integer of 3-6.

[0016] Furthermore, the siloxane ring body includes 2800 parts by mass of dimethylsiloxane ring body (Me2SiO) m 260-300 parts by mass of methylphenylsiloxane ring (MePhSiO) n 8-12 parts by mass of methyl vinyl ring (MeViSiO) b .

[0017] Furthermore, the siloxane ring body includes 2800 parts by mass of dimethylsiloxane ring body (Me2SiO) m 200-260 parts by mass of diphenylsiloxane ring (Ph2SiO) a 8-12 parts by mass of methyl vinyl ring (MeViSiO) b .

[0018] Furthermore, the dimethylsiloxane ring (Me2SiO) m One or a combination of two or more selected from hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and tetradecamethylcycloheptasiloxane.

[0019] Furthermore, the methylphenylsiloxane ring (MePhSiO) n One or a combination of two or more selected from trimethyl-1,3,5-triphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and pentamethylpentaphenylcyclopentasiloxane.

[0020] Furthermore, the diphenylsiloxane ring (Ph2SiO) a One or a combination of two or more selected from hexaphenylcyclotrisiloxane and octaphenylcyclotetrasiloxane.

[0021] Furthermore, the methyl vinyl ring (MeViSiO) b One or a combination of two or more selected from trimethyltrivinylcyclotrisiloxane, pentamethyltrivinylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, tetramethyltrivinylethylcyclotetrasiloxane, tetramethyldivinyldiethylcyclotetrasiloxane, tetramethylvinyltriethylcyclotetrasiloxane, pentamethylpentavinylcyclopentasiloxane and hexamethylhexavinylcyclohexasiloxane.

[0022] The end-capping agent in step (1) is an active end-capping agent, selected from one or a combination of two or more of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,5-divinylhexamethyltrisiloxane, and vinyl silicone oil.

[0023] Furthermore, the end-capping agent has a viscosity of 100-800 mm 2 / s vinyl silicone oil.

[0024] The amount of the end-capping agent in step (1) is 0.1-2.2 wt % of the siloxane ring, preferably 1.3-2.0 wt %. The temperature is raised to 60-65° C., the vacuum dehydration is carried out at -0.090 to -0.10 MPa for 0.5-2 h, and the pressure is released to normal pressure.

[0025] In step (2), the temperature is raised to 150-180° C., and the stirring is performed for 0.5-2 h.

[0026] The catalyst in step (2) is an alkali metal siliconate, selected from one or a combination of two or more of sodium hydroxide siliconate, potassium hydroxide siliconate, and lithium hydroxide siliconate, preferably potassium hydroxide siliconate.

[0027] Furthermore, the amount of the catalyst used is 0.01-0.20 wt %, preferably 0.03-0.06 wt % of the premix.

[0028] Step (2) the first stage ring-opening polymerization reaction time is 1.5-2h, the second stage ring-opening polymerization reaction time is 1.5-4h, and the sum of the first stage ring-opening polymerization reaction time and the second stage ring-opening polymerization reaction time is 3-6h. The first stage ring-opening polymerization inert gas flow rate is 1-10L / min, preferably 2-3L / min. The second stage ring-opening polymerization inert gas flow rate is 1-10L / min, preferably 3-5L / min. The vacuuming is to be vacuumed to -0.01 to -0.09MPa, preferably -0.05MPa to -0.07MPa within 10-20min.

[0029] The co-catalyst in step (2) is selected from one or a combination of two or more of phosphate complexing agents, alcoholamine complexing agents, crown ether complexing agents, and cryptand complexing agents.

[0030] Furthermore, the co-catalyst is selected from one or a combination of crown ether complexing agents and cryptand complexing agents.

[0031] Furthermore, the crown ether complexing agent is selected from one or a combination of two or more of dibenzo-18-crown-6, dibenzo-24-crown-8, benzo-12-crown-4, dibenzo-5-crown-5, 18-crown-6, and 14-crown-4; preferably dibenzo-24-crown-8.

[0032] Furthermore, the cryptand complexing agent is selected from one or a combination of two of 4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5]tricosane and 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane.

[0033] Furthermore, the amount of the co-catalyst is 1.6-3.2wt% of the catalyst. The ring-opening polymerization catalyst is divided into a first-stage ring-opening polymerization reaction catalyzed by an alkali metal silicon alkoxide and a second-stage ring-opening polymerization reaction catalyzed by the alkali metal silicon alkoxide and the co-catalyst. The first stage fully utilizes the alkali metal silicon alkoxide to catalyze the ring-opening polymerization of the siloxane ring body. As the molecular weight increases, the catalytic efficiency of the alkali metal silicon alkoxide decreases relative to the efficiency of the first-stage ring-opening polymerization reaction due to factors such as steric hindrance. Adding the co-catalyst can significantly improve the catalytic efficiency of the alkali metal silicon alkoxide, thereby reducing the overall amount of the alkali metal silicon alkoxide and shortening the ring-opening polymerization reaction time, which is equivalent to using the catalyst tetramethylammonium hydroxide alone.

[0034] The neutralizing agent in step (3) is a silicon-based phosphate, selected from one or a combination of tris(trimethylsilyl)phosphate and tris(triethylsilyl)phosphate. The amount of the neutralizing agent is 0.01-0.3wt% of the premix, preferably 0.03-0.09wt%. The reaction time is 1-3h, preferably 1.5-2h. The temperature is raised to 170-200°C, and the vacuum degassing is vacuumed to -0.090 to -0.10Mpa for 2-6h.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The ring-opening polymerization reaction of the present invention is divided into an alkali metal silicon alkoxide catalytic reaction stage and an alkali metal silicon alkoxide and a co-catalyst catalytic reaction stage. The catalyst is not easily deactivated when in contact with water, and the ring-opening polymerization reaction can be completed in 3-6 hours, which is equivalent to the reaction rate under the catalysis of tetramethylammonium hydroxide. The co-catalyst does not need to be destroyed by adding additional auxiliary agents. Once the alkali metal silicon alkoxide loses its activity, the co-catalyst has no catalytic effect. Moreover, both catalysts do not release gas at high temperatures, and will not have an adverse effect on the mechanical properties of the silicone rubber. Preferably, the ring-opening polymerization reaction is carried out in an inert gas-filled manner in combination with a short-range vacuum polymerization technology, which can effectively control the hydroxyl content and greatly improve the product distribution width.

[0037] The silicone rubber raw rubber prepared by the invention has a transparent appearance and less gel, thereby improving the defect of a conventional product prepared by catalysis with tetramethylammonium hydroxide having a strong odor. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The phenyl silicone rubber prepared in Example 1 1 H-NMR spectrum;

[0039] Figure 2 The phenyl silicone rubber prepared in Example 8 1 H-NMR spectrum. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiment, but is not limited to the content on the specification sheets. Unless otherwise specified, "parts" described in the embodiments of the present invention are all parts by weight. All reagents used are commercially available reagents in this area.

[0041] Example 1

[0042] (1) Add 2800g octamethylcyclotetrasiloxane, 300g tetramethyltetraphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s vinyl silicone oil end-capping agent, stir and mix, heat to 60 ° C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix, which is set aside;

[0043] (2) nitrogen was introduced into the bottom of the premix of step (1) at a flow rate of 2 L / min, the temperature was raised to 160°C, 1.002 g of potassium hydroxide silicon alkoxide catalyst was added and mixed evenly, and the first stage ring-opening polymerization reaction was carried out for 1.5 h; the nitrogen flow rate was adjusted to 3 L / min, the pressure was evacuated to -0.07 MPa within 15 min, 0.016 g of co-catalyst dibenzo-2,4-crown ether-8 was added, and the second stage ring-opening polymerization reaction was carried out for 1.5 h. After the reaction was completed, the pressure was released at a constant temperature and the reaction was set aside;

[0044] (3) Add 1.205 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0045] Example 2

[0046] The rest is the same as Example 1, except that dibenzo-18-crown-6 is used instead of dibenzo-24-crown-8 with the same mass.

[0047] Example 3

[0048] The rest is the same as Example 1, except that an equal mass of 4,7,13,16,21,24-hexaoxo-1,10-diazabicyclo[8.8.8]hexacosane is used instead of dibenzo-24-crown-8.

[0049] Example 4

[0050] The rest is the same as Example 1, except that the amount of dibenzo-24-crown-8 used is 0.010 g.

[0051] Example 5

[0052] The rest is the same as Example 1, except that the amount of dibenzo-24-crown-8 used is 0.035 g.

[0053] Example 6

[0054] (1) Add 2800g octamethylcyclotetrasiloxane, 300g tetramethyltetraphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s vinyl silicone oil end-capping agent, stir and mix, heat to 60 ° C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix, which is set aside;

[0055] (2) nitrogen was introduced into the bottom of the premix of step (1) at a flow rate of 2 L / min, the temperature was raised to 160°C, 1.002 g of potassium hydroxide silicon alkoxide catalyst was added and mixed evenly, and the first stage ring-opening polymerization reaction was carried out for 1.5 h; the nitrogen flow rate was adjusted to 3 L / min, the pressure was evacuated to -0.05 MPa within 15 min, 0.032 g of co-catalyst dibenzo-24-crown ether-8 was added, and the second stage ring-opening polymerization reaction was carried out for 1.5 h. After the reaction was completed, the pressure was released at a constant temperature and the reaction was set aside;

[0056] (3) Add 1.205 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0057] Example 7

[0058] (1) Add 2800g octamethylcyclotetrasiloxane, 300g tetramethyltetraphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s vinyl silicone oil end-capping agent, stir and mix, heat to 60 ° C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix, which is set aside;

[0059] (2) nitrogen was introduced into the bottom of the premix of step (1) at a flow rate of 2 L / min, the temperature was raised to 160°C, 1.002 g of potassium hydroxide silicon alkoxide catalyst was added and mixed evenly, and the first stage ring-opening polymerization reaction was carried out for 1.5 h; the nitrogen flow rate was adjusted to 3 L / min, the pressure was evacuated to -0.09 MPa within 15 min, 0.032 g of co-catalyst dibenzo-24-crown ether-8 was added, and the second stage ring-opening polymerization reaction was carried out for 1.5 h. After the reaction was completed, the pressure was released at a constant temperature and the reaction was set aside;

[0060] (3) Add 1.205 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0061] Example 8

[0062] The rest is the same as Example 1, except that step (1) is to add 2800g octamethylcyclotetrasiloxane, 200g octaphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s of vinyl silicone oil end-capping agent, stir and mix, heat to 60°C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix for standby use.

[0063] (2) nitrogen was introduced into the bottom of the premix of step (1) at a flow rate of 2 L / min, the temperature was raised to 180°C, 1.545 g of potassium hydroxide siliconate catalyst was added and mixed evenly, and the first stage ring-opening polymerization reaction was carried out for 2 h; the nitrogen flow rate was adjusted to 3 L / min, the pressure was evacuated to -0.06 MPa within 15 min, 0.032 g of co-catalyst dibenzo-24-crown ether-8 was added, and the second stage ring-opening polymerization reaction was carried out for 2 h. After the reaction was completed, the pressure was released at a constant temperature and the reaction was set aside;

[0064] (3) Add 1.856 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0065] Example 9

[0066] The rest is the same as Example 1, except that the amount of tetramethyltetraphenylcyclotetrasiloxane used in step (1) is 260 g.

[0067] Comparative Example 1

[0068] (1) Add 2800g octamethylcyclotetrasiloxane, 300g tetramethyltetraphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s vinyl silicone oil end-capping agent, stir and mix, heat to 60 ° C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix, which is set aside;

[0069] (2) nitrogen was introduced into the bottom of the premix of step (1) at a flow rate of 2 L / min, the temperature was raised to 160°C, 1.002 g of potassium hydroxide siliconate catalyst was added and mixed evenly, and the first stage ring-opening polymerization reaction was carried out for 1.5 h; the nitrogen flow rate was adjusted to 3 L / min, 0.032 g of co-catalyst dibenzo-2,4-crown-8 was added, and the second stage ring-opening polymerization reaction was carried out for 1.5 h. After the reaction was completed, the pressure was released at a constant temperature and the reaction was set aside;

[0070] (3) Add 1.205 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0071] Comparative Example 2

[0072] (1) Add 2800g octamethylcyclotetrasiloxane, 300g tetramethyltetraphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s vinyl silicone oil end-capping agent, stir and mix, heat to 60 ° C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix, which is set aside;

[0073] (2) Raise the temperature to 160° C., add 1.002 g of potassium hydroxide siliconate as a catalyst and mix well, and carry out the first stage ring-opening polymerization reaction for 1.5 h; evacuate to -0.06 MPa within 15 min, add 0.032 g of co-catalyst dibenzo-2,4-crown-8, and carry out the second stage ring-opening polymerization reaction for 1.5 h. After the reaction is completed, release the pressure at a constant temperature and set aside;

[0074] (3) Add 1.205 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0075] Comparative Example 3

[0076] The rest is the same as Example 1, except that the co-catalyst dibenzo-24-crown-8 is replaced by an equal mass of the catalyst potassium hydroxide siliconate.

[0077] Comparative Example 4

[0078] (1) Add 2800g octamethylcyclotetrasiloxane, 300g tetramethyltetraphenylcyclotetrasiloxane, 8g tetramethyltetravinylcyclotetrasiloxane, 60g viscosity 600mm into the reactor. 2 / s vinyl silicone oil end-capping agent, stir and mix, heat to 60 ° C, vacuum dehydrate at -0.09 MPa for 2 hours, and release the pressure to normal pressure to obtain a premix, which is set aside;

[0079] (2) nitrogen was introduced into the bottom of the premix of step (1) at a flow rate of 2 L / min, the temperature was raised to 160° C., 1.002 g of potassium hydroxide silicon alkoxide catalyst and 0.032 g of co-catalyst dibenzo-2,4-crown ether-8 were added and mixed evenly, and the mixture was evacuated to -0.06 MPa within 15 min, and a ring-opening polymerization reaction was carried out for 3 h. After the reaction was completed, the pressure was released at a constant temperature and the mixture was set aside;

[0080] (3) Add 1.205 g of tris(trimethylsilyl) phosphate as a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix well and react for 2 h. After the reaction is completed, heat to 180° C., evacuate to -0.09 MPa and remove the pressure for 3 h to obtain phenyl silicone rubber raw rubber.

[0081] Application Example 1

[0082] 1800 g of the phenyl silicone rubber obtained in Example 1 was taken, 750 g of white carbon black, 80 g of hydroxyl silicone oil JS-209 (hydroxyl mass fraction 6.0%) structure control agent, and 50 g of peroxide dipentadienyl vulcanizing agent were added, and vulcanization was carried out at 200° C. for 4 h to obtain vulcanized phenyl silicone rubber.

[0083] Application Example 2-9

[0084] The rest is the same as that of Application Example 1, except that the phenyl silicone rubber raw rubber is prepared according to Example 2-9.

[0085] Comparative Application Examples 1-4

[0086] The rest is the same as that of Application Example 1, except that the phenyl silicone rubber raw rubber is prepared according to Comparative Examples 1-4.

[0087] The silicone rubber prepared in the above examples and comparative examples was subjected to the following performance tests: The results are shown in Table 1

[0088] 1. The products of Example 1 and Example 7 were characterized using an AVANCE AV400MHZ nuclear magnetic resonance spectrometer from Bruker, Germany;

[0089] 2. Molecular weight and molecular weight distribution test: Waters 515-2410 gel permeation chromatograph was used, with polystyrene as the standard and tetrahydrofuran as the mobile phase at a flow rate of 1.0 mL / min.

[0090] 3. Hydroxyl content test: The hydroxyl content is calculated by measuring the intensity of the hydroxyl absorption peak in the infrared spectrum of the silicone rubber sample using the near-infrared method.

[0091] 4. Yield: Calculate according to the following formula:

[0092] Yield = actual output of raw rubber / (amount of siloxane ring body input + amount of end-capping agent input) * 100%, for calculation.

[0093] The following properties of the vulcanized phenyl silicone rubber prepared in the above application examples and comparative application examples were tested: The results are shown in Table 2

[0094] 1. Sticky roller level: The judgment criteria are as follows, divided into 5 levels, among which level -2 is the most sticky roller, level 2 is the driest and does not stick to the roller. Specifically:

[0095] 2. Without roller, it will automatically fall off after being put on the roller and fall onto the tray;

[0096] 1. The roller can be wrapped and will not fall off automatically, but the rubber material is not in close contact with the roller surface after wrapping, and no accumulated rubber can be formed;

[0097] 0. It can wrap the roller and form normal rubber accumulation, which can be separated from the roller surface normally after tapping;

[0098] -1 The rubber material sticks to the roller surface immediately after being put on the roller and is difficult to separate after tapping, but can be peeled off by pulling;

[0099] -2 After being rolled up, it becomes sticky and difficult to peel off. It must be peeled off with the help of tools such as scrapers.

[0100] 2. Shore hardness: Refer to standard GB / TGB / T528-2009. First, wipe the sample surface with absorbent cotton dipped in anhydrous ethanol. Then, press the hardness tester needle on the surface of the vulcanized rubber sample and record the reading shown by the pointer.

[0101] 3. Tensile strength: Dumbbell-shaped specimens, with dimensions conforming to GB / T528-2009 and a distance of 25 mm between two markings, were used for testing mechanical properties using an INSTRON-1185 universal testing machine at a tensile speed of 500 mm / min.

[0102] 4. Tear strength: The sample size complies with GB / T528-2009 and is cut using a cutting machine.

[0103] Table 1

[0104]

[0105] Table 2

[0106]

[0107]

[0108] Note: Example 5 was difficult to absorb powder, and Comparative Application Examples 2 and 3 were difficult to conduct subsequent application tests because the rubber materials were too sticky, so no data could be provided.

[0109] Depend on Figure 1 1 The results of the H-NMR spectrum show that the peaks with chemical shifts of 7.243ppm, 7.236ppm, and 7.496ppm are characteristic peaks of hydrogen atoms on the benzene ring; the peak at 0.200-0.300ppm is the characteristic peak of the hydrogen atoms of the methyl group on the methylphenyl chain segment. Since the molar proportion of vinyl in the raw rubber is very low, there is a less obvious characteristic peak of hydrogen atoms in the Si-CH=CH2 chain segment at 5.4-6.0ppm, indicating that phenyl silicone rubber was successfully synthesized in Example 1. Similarly, from Figure 2 1 The H-NMR spectrum results showed that the target product was also prepared in Example 8. Since Example 8 did not have a methylphenyl chain segment, the characteristic peak of the methyl hydrogen atom on the methylphenyl chain segment did not appear at 0.200-0.300 ppm.

[0110] It can be seen from Table 1 that dividing the ring-opening polymerization reaction into an alkali metal silicon alkoxide catalytic reaction stage and an alkali metal silicon alkoxide and a co-catalyst coordinated catalytic reaction stage can not only shorten the ring-opening polymerization reaction time, but also prepare phenyl silicone rubber with a large molecular weight and a relatively narrow molecular weight distribution.

[0111] From Tables 1 and 2, especially Examples 1, 2, 3, 8, and 9, it can be seen that the ring-opening polymerization reaction is carried out by blowing inert gas throughout the process in combination with short-range vacuum polymerization technology, which can effectively control the hydroxyl content and greatly improve the product distribution width. The obtained mono- and diphenyl rubber products have high yields, uniform distribution, and are colorless and transparent in appearance, do not stick to the roller, do not fall off the roller, and have excellent mechanical properties.

[0112] The silicone rubber raw rubber prepared by the invention has a transparent appearance and less gel, thereby improving the defect of a conventional product prepared by catalysis with tetramethylammonium hydroxide having a strong odor.

[0113] The above detailed description is a specific description of one feasible embodiment of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not depart from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for preparing phenyl silicone rubber raw rubber by a one-pot process, characterized in that: The steps include: (1) Adding siloxane ring body and end-capping agent to prepare premix; (2) adding a catalyst to the premix obtained in step (1) to carry out a first-stage ring-opening polymerization reaction; and continuing to add a co-catalyst to carry out a second-stage ring-opening polymerization reaction; (3) adding a neutralizing agent to the ring-opening polymerization product of step (2) and continuing the reaction to obtain a phenyl silicone rubber raw rubber; the catalyst in step (2) is an alkali metal silicon alkoxide; the co-catalyst is selected from a combination of one or more of a phosphate complexing agent, an alcohol amine complexing agent, a crown ether complexing agent, and a cryptand complexing agent.

2. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 1, characterized in that: The specific steps include: (1) Add siloxane ring body and end-capping agent into the reaction kettle, stir and mix, heat, vacuum dehydrate, and release the pressure to obtain a premix for use; (2) introducing an inert gas into the premix of step (1), raising the temperature, adding a catalyst and mixing uniformly, and carrying out a first-stage ring-opening polymerization reaction; adjusting the inert gas flow rate, evacuating the mixture, adding a co-catalyst, and carrying out a second-stage ring-opening polymerization reaction; after the reaction is completed, releasing the pressure at a constant temperature to obtain a ring-opening polymerization product, which is then set aside; (3) Add a neutralizing agent to the ring-opening polymerization product of step (2) under normal pressure, mix and react evenly, and after the reaction is completed, heat and vacuum to obtain phenyl silicone rubber raw rubber.

3. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 1 or 2, characterized in that: The siloxane ring body in step (1) includes 2800 parts by mass of dimethylsiloxane ring body (Me2SiO) m 260-300 parts by mass of methylphenylsiloxane ring (MePhSiO) n , 8-12 parts by mass of methyl vinyl ring; or, The siloxane ring body includes 2800 parts by mass of dimethylsiloxane ring body (Me2SiO) m 200-260 parts by mass of diphenylsiloxane ring (Ph2SiO) a , 8-12 parts by mass of methyl vinyl ring body, wherein m is an integer of 3-7, n is an integer of 3-5, and a is an integer of 3-4.

4. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 3, characterized in that: The dimethylsiloxane ring (Me2SiO) m A combination of one or more selected from hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, and tetradecamethylcycloheptasiloxane; the methylphenylsiloxane ring (MePhSiO) n A combination of one or more selected from trimethyl-1,3,5-triphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and pentamethylpentaphenylcyclopentasiloxane; the diphenylsiloxane ring (Ph2SiO) a The methyl vinyl ring body is selected from the group consisting of trimethyltrivinylcyclotrisiloxane, pentamethyltrivinylcyclotetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, tetramethyltrivinylethylcyclotetrasiloxane, tetramethyldivinyldiethylcyclotetrasiloxane, tetramethylvinyltriethylcyclotetrasiloxane, pentamethylpentavinylcyclopentasiloxane and hexamethylhexavinylcyclohexasiloxane.

5. The method for preparing phenyl silicone rubber raw rubber by one-pot process according to claim 1 or 2, characterized in that: The alkali metal siliconate in step (2) is selected from a combination of one or more of sodium hydroxide siliconate, potassium hydroxide siliconate, and lithium hydroxide siliconate.

6. The method for preparing phenyl silicone rubber raw rubber by one-pot process according to claim 5, characterized in that: The alkali metal siliconate in step (2) is potassium hydroxide siliconate.

7. The method for preparing phenyl silicone rubber raw rubber by one-pot process according to claim 1 or 2, characterized in that: The amount of the catalyst used is 0.01-0.20 wt % of the premix.

8. The method for preparing phenyl silicone rubber raw rubber by one-pot process according to claim 7, characterized in that: The amount of the catalyst used is 0.03-0.06 wt % of the premix.

9. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 2, characterized in that: In step (2), the first-stage ring-opening polymerization reaction time is 1.5-2 hours, the second-stage ring-opening polymerization reaction time is 1.5-4 hours, and the sum of the first-stage ring-opening polymerization reaction time and the second-stage ring-opening polymerization reaction time is 3-6 hours; the inert gas flow rate of the first-stage ring-opening polymerization is 1-10 L / min; the inert gas flow rate of the second-stage ring-opening polymerization is 1-10 L / min; and the vacuuming is to reduce the vacuum to -0.01 to -0.09 MPa within 10-20 minutes.

10. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 9, characterized in that: In step (2), the inert gas flow rate of the first stage ring-opening polymerization is 2-3 L / min; the inert gas flow rate of the second stage ring-opening polymerization is 3-5 L / min; and the vacuuming is to reduce the vacuum to -0.05 MPa to -0.07 MPa within 10-20 minutes.

11. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 1 or 2, characterized in that: The amount of the co-catalyst used in step (2) is 1.6-3.2 wt% of the catalyst; the co-catalyst is selected from one or a combination of crown ether complexing agents and cryptand complexing agents.

12. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 11, characterized in that: The crown ether complexing agent is selected from a combination of one or more of dibenzo-18-crown-6, dibenzo-24-crown-8, benzo-12-crown-4, dibenzo-5-crown-5, 18-crown-6, and 14-crown-4; the cryptand complexing agent is selected from a combination of one or two of 4,7,13,16,21-pentaoxa-1,10-diazabicyclo[8.8.5]tricosane and 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane.

13. The method for preparing phenyl silicone rubber raw rubber by a one-pot process according to claim 12, characterized in that: The crown ether complexing agent is dibenzo-24-crown-8.

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