WO2021179298A1

WO2021179298A1 - Method for preparing silicone rubber sponge thermal insulation material by adopting in-situ graft modified mesoporous silica vesicle continuous aggregate as functional filler

Info

Publication number: WO2021179298A1
Application number: PCT/CN2020/079262
Authority: WO
Inventors: 康旭
Original assignee: 新华盛节能科技股份有限公司
Priority date: 2020-03-12
Filing date: 2020-03-13
Publication date: 2021-09-16
Also published as: CN111303633B; CN111303633A

Abstract

Disclosed in the present invention are a method for preparing a premix by means of in-situ graft modification of a mesoporous silica vesicle continuous aggregate, and a method for preparing an addition-type silicone rubber sponge thermal insulation material by using the premix as a main raw material. (1) Under the action of an alkaline catalyst, a vinyl-terminated silicone oil, water and a vesicle are subjected to a chemical equilibrium reaction, and silicon hydroxyl generated in situ exists in three different forms: silicon hydroxyl grafted at the end of polysiloxane on the surface of the vesicle; silicon hydroxyl grafted at two ends of polysiloxane; and mixed terminated polysiloxane with one end of mixed terminated polysiloxane and one end of vinyl. The graft ratio of the vesicle surface, the content of silicon hydroxyl-terminated polysiloxane and the content of vinyl-terminated polysiloxane of the premix can be controlled by adjusting the proportion of the raw material and the like, achieving in-situ graft modification of the vesicle and synthesis of an active hydroxyl component. The process has few steps, no pollution, and low smell. (2) An addition-type silicone rubber sponge is prepared by using the premix as the main raw material. Liquid silicone rubber has a low viscosity and a high strength, and the thermal conductivity coefficient thereof decreases with the increase of the addition proportion of the vesicle.

Description

Method for preparing silicon rubber sponge heat insulation material by using continuous aggregates of mesoporous silica vesicles modified by in-situ grafting as functional fillers

Technical field

The present invention relates to an in-situ grafted modified mesoporous silica vesicle continuous aggregates (hereinafter referred to as vesicles) synergistic premix and a modification method. The present invention also relates to an in-situ grafting method containing the above-mentioned premix A silicone rubber sponge heat-insulating material capable of synergizing branch modified vesicles and a preparation method thereof.

Background technique

At present, flexible thermal insulation materials usually refer to traditional polyurethane sponges with a thermal conductivity as low as 0.02W/(m·K). The disadvantages are poor temperature resistance, high water absorption, easy degradation, and high combustion smoke toxicity. Silicone rubber sponge, also known as silicone rubber foam, is a porous sponge-like polymer elastomer made of silicone rubber through a foaming molding process. It has low density, heat resistance, flame retardancy, heat insulation, sound insulation, A series of advantages such as shock absorption, damping, water resistance, weather resistance, permanent low compression, and good air tightness. The silicone rubber sponge currently on the market can withstand long-term temperature -55℃～200℃, flame retardant FVO grade, drip resistance, good smoke suppression, non-toxic smoke, hydrophobic and moisture barrier, but its thermal conductivity is 0.05W /(m·K), the heat preservation effect is not ideal. With the decline in the cost of silicone rubber and the maturity of technology, silicone rubber sponge is expected to become a very promising flexible thermal insulation material.

The key to further reducing the thermal conductivity of silicone rubber sponge lies in reducing the apparent density and reducing the cell diameter. As we all know, the thermal conductivity of silica aerogel, glass beads, air and silicone rubber are around 0.018, 0.030, 0.026 and 0.20W/(m·K), respectively. Increasing the volume ratio of air and lightweight fillers is beneficial to Amplitude silicone rubber foam reduces thermal conductivity. In patent document CN103130454A, the thermal conductivity of the silicone rubber foam matrix with ultra-high proportion of hollow glass beads added to the condensed liquid silicone rubber is 0.048W/(m·K), and the thermal conductivity of the product further added with aerogel is reduced to 0.02W/(m·K), but the addition of a high proportion of non-reinforcing fillers will inevitably cause the foam to lose its resilience and toughness. Patent document WO2018148290A1 adds 9.09/% by mass of glass hollow microspheres to conventional addition-molding liquid silicone rubber without foaming, and its apparent density and thermal conductivity are only 0.87g/cm ³ and 0.17W/(m) ·K), the effect is not significant.

Patent document US9488311 uses a thermal decomposition foaming agent to increase the expansion ratio, the apparent density is less than 0.080g/cm ³ , and the thermal conductivity is less than 0.04W/(m·K), but the cell diameter produced by thermal decomposition is coarse and uneven , Air convection is not conducive to reducing thermal conductivity. Patent document US5010115 uses an addition-molding liquid silicone rubber system. Under the action of platinum catalyst, long-chain alkyl alcohol and hydrogen-containing siloxane are dehydrogenated and foamed, and the apparent density is as low as 0.050g/cm ³ , but this system has no reinforcing filler. , The strength is poor, the guidance is strong, and the practicability is poor. Generally, liquid silicone rubber has low surface tension, lipophilic and hydrophobic properties, and low mechanical strength. The surface-modified fumed silica with high specific surface area is an ideal reinforcing agent, and the enhancement effect is about 50 times. Therefore, a small amount of aerogel, diatomaceous earth, montmorillonite, vermiculite, etc. are usually added to the addition-formed foamed liquid silica gel reinforced by fumed silica as a thickening agent, together with surfactants, to refine The droplet diameter of the water-in-oil can increase the nucleation density, and has a significant impact on the cell pore type, cell density, pore size distribution and apparent density of the foam. It is described in US20180057652A1, JPWO2017110565A1, US20110021649A1, US4460713, WO2005085357A1 and other patents. The literature has mentioned it, but the amount of thickener added is too small, and the thickener itself has a very limited effect on the thermal conductivity. In addition, the thermal insulation performance of the aerogel decreases after water absorption, so patent documents KR20090061301A and US 6475561B1 deliberately perform hydrophobic treatment on the silanol groups present on the surface of the aerogel, which effectively reduces the water absorption of the aerogel and makes its thermal insulation performance. Significantly increased. Although hydrophobizing hydrophilic fillers such as aerogel, glass hollow microspheres, diatomaceous earth, montmorillonite, vermiculite, etc. can reduce the thickening of the filler, the deviation of the reinforcement of the high proportion of addition of rubber is Both flexibility and resilience have varying degrees of loss.

Studies have shown that when the diameter of the pores in the material is reduced to nanometers, it will produce nano-effects such as "zero convection", "infinitely many heat shields", and "infinitely long paths", which reduces the material's heat transfer ability to close to the limit. Preparation of super insulation materials. Vesicles can be understood as a three-dimensional cluster network composed of nano-scale hollow silica beads, while fumed silica is a three-dimensional dendritic network composed of nano-scale solid silica microspheres. There are nano-sized high pores inside and between the vesicles, the latter between solid particles = nano-sized high gaps, so the packing density of the two is low, and both are suitable for preparing super thermal insulation materials. For example, in the patent documents CN106478053A, CN106747261A, and CN106699106A, mesoporous silica vesicles were prepared by in-situ hydrolysis in the liquid phase with added fibers, and the thermal conductivity was as low as 0.02W/(m·K) or less. The product prepared by the patent document CN103922347B is a continuous vesicle with a size of 20-100nm, the pore wall thickness is 4-6nm, the pore size distribution is hierarchical pores, the gap between the walls is 2-4nm, the vesicle pore size is 20-40nm, and the specific surface area is 600～1100m ² /g; product uniformity is good, density is about 40kg/m ³ ; high temperature performance at 850℃ is stable, and the pore structure remains intact under 10MPa pressure. Therefore, it can be expected that the surface hydrophobically modified lightweight porous vesicles added to the silicone rubber with high foaming ratio will combine the micron-level void structure of the silicone rubber with the nano-level voids of the vesicles. The thermal conductivity of the silicone rubber, such as The proportion of bubbles increases and decreases drastically.

Summary of the invention

The technical problem to be solved by the present invention is to provide an in-situ grafted modified vesicles synergistic premix and at the same time provide a modification method of the premix. The invention also provides an in-situ grafted modified vesicle synergistic silicone rubber sponge heat insulation material with low thermal conductivity and a preparation method thereof.

In order to solve the above technical problems, the present invention uses vesicles with high porosity and low thermal conductivity as the main filler to prepare high foaming rate silicone rubber. The coefficient reaches 0.034W/(m·K).

First, the hydrophobic treatment of hydrophilic vesicles on the surface by in-situ surface chemical grafting was realized, and the compatibility and dispersibility of vesicles in liquid silicone rubber were improved. With low thickening vesicles The increase in the addition amount of silicone rubber significantly reduces the thermal conductivity of silicone rubber, especially when it is rented with high foaming ratio and molded silicone rubber, which has a significant synergistic effect on reducing the thermal conductivity; secondly, the hydrophilic inner cavity of the vesicles The active hydrogen-containing component of the molded foamed silicone rubber has a selective adsorption effect. It has a large adsorption capacity for water and alcohol with small molecular weight and high polarity, and the foaming ratio is unstable in batches, so it is not applicable. Using low-polarity and relatively large-molecular-weight hydroxyl-terminated polysiloxane as the active hydrogen-containing component, the vesicle has low adsorption to it, ensuring the foaming ratio of the foamed silicone rubber is stable, and the flexibility of the silicone rubber is The batch stability of the product with resilience and thermal conductivity is good.

An in-situ grafted modified vesicle synergistic premix, which includes the following components by mass:

(A) The vinyl-terminated silicone oil is a vinyl-terminated polysiloxane with a viscosity of 5000 to 200000 mPa.s, and its side chain is a methyl group or a combination of a methyl group and a phenyl group. The preferred mass parts of the (A) terminal vinyl silicone oil is 1800 to 2000.0 parts.

(B) Water, tap water, purified water, distilled water, deionized water can be used. The (B) water is preferably 20.0 to 30.0 parts.

(C) The basic catalyst is lithium hydroxide, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide or a balance of potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide and siloxane (the industry said Alkaline gum), preferably tetramethylammonium hydroxide. The methods of using different catalysts are well known in the industry and will not be repeated here. The (C) basic catalyst is preferably 3.0 to 4.0 parts.

(D) Vesicles are continuous aggregates of mesoporous silica vesicles. The size of the continuous vesicles is 20-100nm, the thickness of the pore wall is 4-6nm, the pore size distribution is hierarchical pores, and the gap between the walls is 2～4nm. The bubble diameter is 20-40nm, the specific surface area is 600-1100m ² /g; the density is about 40kg/m ³ ; the performance is stable at 850°C, and the pore structure remains intact under the pressure of 10MPa. The (D) vesicles are preferably 500.0 to 800 parts.

In-situ grafted modified vesicle synergistic silicone rubber sponge heat insulation material, which includes the following components by mass:

(E) The premix is the synergistic premix of the above-mentioned in-situ grafted modified vesicles, and its addition amount needs to be adjusted according to the formula to increase the proportion of vesicles as much as possible.

(F) The platinum catalyst is an alcohol or ether complex of chloroplatinic acid, triphenylphosphine platinum, chloroplatinic acid, and an alkenyl complex of platinum. Preference is given to platinum compounds soluble in polysiloxanes, such as alkenyl complexes of platinum. Alkenyl ligands in platinum alkenyl complexes are olefins, vinylsiloxanes or tetramethyldivinyldisiloxane compounds, and diethylenetetramethyldisiloxane platinum complexes and tetramethyldisiloxane are particularly preferred. Methyltetravinylcyclotetrasiloxane platinum complex. The platinum group metal catalyst can promote the hydrosilylation reaction of silicon hydrogen atoms and vinyl groups to form cross-linked silicone rubber elastomers, and can also promote the reaction of silicon hydrogen and the hydroxyl groups in the blowing agent to produce hydrogen foaming. The amount of platinum catalyst added is 10 to 200 ppm, preferably 30 to 50 ppm. From the viewpoint of cost performance and production efficiency, it is beneficial to increase the added amount.

(G) Inhibitors, hydrosilylation inhibitors retard the crosslinking rate and foaming rate during the mixing operation. Inhibitors can be selected from vinyl siloxane, acetylenic alcohol, phosphite, unsaturated amide or maleate, preferably vinyl siloxane or acetylenic alcohol, such as tetramethyl divinyl disiloxane, tetramethyl Tetravinylcyclotetrasiloxane, methylbutynol and ethynylcyclohexanol, etc.

(I) Hydrogen-containing siloxane, preferably hydrogen-containing siloxane is a cyclic, linear or branched hydrogen-containing siloxane. The hydrogen atom directly connected to the silicon atom in the hydrogen-containing silane undergoes an addition reaction with the vinyl group, cross-linking and curing to form an elastomer; the hydrogen atom and the active hydrogen-containing hydroxy silicone oil undergo a dehydrogenation condensation reaction, not only foaming, but also Cross-linking effect. The hydrosilyl group of the hydrogen-containing siloxane can be located at any position in the molecular chain, and the other groups connected to the silicon atom can be any alkane, alkene and aromatic hydrocarbon, and most preferably all are methyl groups.

The viscosity (25°C) of the hydrogen-containing siloxane in the present invention is 10.0 to 50.0 mPa·s, more preferably 20.0 to 30.0 mPa·s. The hydrogen content of the hydrogen-containing siloxane is 0.1 to 1.67%, more preferably 1.5% to 1.6%. Hydrogen-containing siloxanes of various structures can be selected from one or more optimized combinations.

The above-mentioned in-situ graft modification method of vesicles: use (A) terminal vinyl silicone oil, (B) water and (D) vesicles as raw materials, and form a premix under the action of (C) alkaline catalyst; In the mixture, the hydroxyl-terminated polysiloxane is produced in situ under the action of (C) alkaline catalyst, and a part of the reactive hydroxyl group of the hydroxyl-terminated polysiloxane is condensed with the silanol on the surface of the vesicle to form a graft modification. ; Another part of the hydroxy-terminated polysiloxane is dissolved in the premix; the premix contains the following components by mass:

The surface-modified fumed silica with high specific surface area is an ideal reinforcing agent, and the enhancement effect is about 50 times. Modification method commonly used in the industry: Add silazane, water, silicone oil, fumed silica and hydroxyl-terminated polysiloxane and other raw materials in the kneader. Under high shear, the silazane is hydrolyzed The silanol on the surface of the method silica reacts to change its surface from hydrophilic to hydrophobic. Experiments found that the internal cavity of the vesicle treated by this method adsorbed residual ammonia gas, and the actual effect of increasing the temperature, increasing the vacuum degree, and prolonging the depletion time was not good. The platinum catalyst of addition-molded liquid silicone rubber is easily poisoned and invalidated after coordination with ammonia gas. In addition, in the literature, the silane treatment agent is used to hydrolyze the ethanol, and the released ethanol is flammable and explosive, and there is a certain degree of danger. From the retrospective thinking of the matching between the vesicle characteristics and the active hydrogen-containing substances in the formula, this patent finds that hydroxyl-terminated polysiloxane is not only an active hydrogen substance that generates bubbles, but also a commonly used auxiliary agent for gas phase processing. It uses vinyl silicone oil. , Water, alkaline catalyst and vesicles as raw materials, in situ generated active hydroxyl groups condense with silanol on the surface of the vesicles, grafting silicone oil segments on the surface of the vesicles, the grafting amount can be controlled by adjusting the ratio of raw materials and process conditions. This mixture is collectively referred to as a premix.

Adjusting the raw material ratio and process parameters of the premix can optimize the vesicle grafting amount, active hydroxyl content and viscosity of the premix, and further verification and comparison of the formulation of the addition-molded liquid foamed silicone rubber will help. Understand the unique advantages of the reverse design of this patent.

The preparation method of in-situ grafted modified vesicle synergistic silicone rubber sponge heat insulation material includes the following steps:

(1) In-situ graft modification of the above-mentioned vesicles to obtain (E) premix. Using vinyl-terminated silicone oil, water and vesicles as raw materials, a hydroxyl-terminated polysiloxane is produced in situ under the action of an alkaline catalyst, and a part of the hydroxyl-terminated polysiloxane reacts with active hydroxyl groups on the surface of the vesicles. The hydroxyl group is condensed to form graft modification, and the grafting amount can be controlled by adjusting the ratio of raw materials and controlling the process parameters; another part of the hydroxyl-terminated polysiloxane is dissolved in the mixture. Both of these two active hydrogen-containing hydroxy-terminated polysiloxanes can react with hydrogen-containing siloxane to generate gas. The method has few process links, no pollution, and low odor. The mixture is collectively referred to as a premix.

(2) Add (E) premix, (F) platinum catalyst, (G) inhibitor, (H) terminal vinyl silicone oil and (I) hydrogen-containing siloxane in sequence, stir evenly and defoam quickly, and pour it into the mold Start to foam until the surface is not sticky and the sponge volume is stable, the (E) premix, (F) platinum catalyst, (G) inhibitor, (H) terminal vinyl silicone oil and (I) hydrogen-containing silicon The mass parts of oxane are:

The silanol group is generated in situ in the premix, and there is no need to add additional active hydroxyl-containing material components. The silanol group exists in three forms: the end of the polysiloxane grafted on the surface of the vesicle, and the two components of the polysiloxane. The specificity of the polymer structure determines the specificity of silicone rubber.

The addition type silicone rubber sponge is generally composed of vinyl-containing polysiloxane, hydrogen-containing polysiloxane, fillers, catalysts, inhibitors, foaming agents and various additives. Under the catalytic action of vinyl polysiloxane, hydrogen-containing polysiloxane and foaming agent, the hydrosilylation crosslinking reaction and the hydrosilylation dehydrogenation condensation reaction occur, that is, the crosslinking and foaming are carried out at the same time, and the control of the two The rate ratio can be used to prepare silicone rubber sponges with different cell pore types, cell density, pore size distribution and apparent density. The chemical foaming process includes three stages: cell nucleation-cell growth/merging-cell shaping. The degree of development of each stage is closely related to the degree of crosslinking and curing. The ideal state is that these two processes are separated as much as possible. However, the reality is that these two processes are inseparable, and both processes are extremely sensitive to temperature. How to control this equilibrium point is always a severe challenge.

The size of continuous vesicles is 20-100nm, the pore wall thickness is 4-6nm, the pore size distribution is hierarchical pores, the gap between the walls is 2-4nm, the vesicle pore size is 20-40nm, and the specific surface area is 600-1100m ² /g; The uniformity is good, the density is about 40kg/m ³ ; the high temperature performance is stable at 850℃, and the pore structure remains intact under the pressure of 10MPa. Vesicles can be understood as a three-dimensional cluster network formed by the combination of nano-scale hollow silica microspheres, while fumed silica is a three-dimensional dendritic network formed by the combination of nano-scale solid silica microspheres. High void ratio, high void ratio between the latter particles, the bulk density of both are low. Therefore, when the two are added with the same mass of liquid silicone rubber, due to the high porosity and low density of the vesicles, the volume ratio of the vesicles is significantly higher than that of the gas phase when converted to the volume ratio of the filler to the polysiloxane polymer. The viscosity of the composition of the method silica is also much higher than that of the liquid silicone rubber reinforced by gas silicon.

Hydrophilic vesicles have a large number of silanol groups on both the inner and outer surfaces, which can adsorb a large number of water molecules. The direct addition of unmodified hydrophilic vesicles in the addition-molded foamed liquid silicone rubber will cause serious problems: one is that the vesicles have high water absorption and their own thermal conductivity increases; the other is that the vesicles have high thickening properties and are difficult to Adding in a high proportion has little contribution to reducing the overall thermal conductivity; third, the silanol and adsorbed water on the outer surface of the vesicles are both active hydrogen-containing substances, and under the action of platinum catalysts, both can interact with hydrogen-containing siloxanes. The dehydrogenation condensation reaction affects the foaming rate and crosslinking rate of the system, the foaming ratio of silicone rubber is unstable, and the thermal conductivity of the product fluctuates. In addition, vesicles have an inner surface and an outer surface, which is different from fumed silica only with the outer surface. Although there are nano-scale pores on the surface, the inner surface of the vesicle still remains hydrophilic. Addition molding foamed silicone rubber must be added with active hydrogen-containing substances, common ones include water, alkyl alcohol and hydroxy silicone oil, some of which are absorbed into the inside of the vesicle and no longer participate in the reaction outside the vesicle, which limits the amount of active hydrogen-containing substances. Select the range. The hydrophilic inner cavity of the vesicle has strong adsorption of small molecular weight and high polarity water and alkyl alcohol, making the mass percentage of water and alkyl alcohol unstable, leading to batch fluctuations in foaming ratio and pore distribution The hydrophilic inner surface of the vesicle has a weak adsorption effect on the low-polarity hydroxy silicone oil with a relatively large molecular weight. The use of hydroxy silicone oil to provide active hydrogen is beneficial to improve the stability of the product batch and reduce the thermal conductivity.

The surface-modified premix of the vesicles of the present invention uses vinyl silicone oil, water and vesicles as raw materials. Under the action of an alkaline catalyst, hydroxyl-terminated polysiloxane is produced in situ, and a part of hydroxyl-terminated polysiloxane is produced in situ. The reactive hydroxyl of oxane reacts with the silanol on the surface of the vesicle to condense to form a graft modification; another part of the hydroxyl-terminated polysiloxane is dissolved in the mixture. Both of these two active hydrogen-containing hydroxy-terminated polysiloxanes can react with hydrogen-containing siloxane to generate gas. The modification method has few process links, no pollution, and low odor. The above-mentioned mixtures are collectively referred to as premixes. The silanol group is generated in situ in the premix, and there is no need to add additional active hydroxyl-containing material components. The silanol group exists in three forms: the end of the polysiloxane grafted on the surface of the vesicle, and the two components of the polysiloxane. The specificity of the polymer structure determines the specificity of silicone rubber. The addition molding silicone rubber with premix as the main raw material has a high foaming ratio, and the high proportion of vesicles has a significant contribution to reducing the thermal conductivity, and the thermal conductivity reaches 0.034W/(m·K).

Detailed ways

The first step: using surface chemical modification method to make the surface hydrophilic vesicles hydrophobic.

In the kneader, add vinyl-terminated silicone oil, water and alkaline catalyst in sequence, close the lid, turn on the kneading, and set a temperature of 90 degrees to react for 60 minutes to generate hydroxyl-terminated polysiloxane in situ. Open the lid, add the vesicles in batches, and knead for 5.0 hours. Set the temperature to 180 degrees, continue kneading for 2.0 hours, then turn on the vacuum pump and knead under negative pressure for 3 hours to remove volatiles. Stop heating, stop kneading, turn off the vacuum pump, release the vacuum, wait until the temperature of the material drops below 40 ℃ to discharge the material for later use.

According to the above method, the corresponding raw materials were added in each embodiment.

Table 1 The influence of terminal vinyl silicone oil viscosity in different embodiments

E in the table represents an embodiment, the same below.

Theoretically, one molecule of water produces two active silanol groups, and 10 g of water produces at least 1000 mmol silanol groups, which is much higher than the 120 mmol vinyl groups contained in 2000 g of 5000 mPa.s vinyl-terminated silicone oil. Under the action of alkaline catalyst, the vinyl-terminated silicone oil undergoes a series of hydrolysis, condensation, termination, cyclization, ring opening, etc. The actual silanol group may be far less than 1000 mmol. When the process is consistent, the viscosity of the premix increases as the silicone oil increases.

Table 2 The influence of water volume on the viscosity of premix

In Table 2, in different embodiments E-6, E-7, E-8, E-9, and E-10, the water is tap water, purified water, distilled water, and deionized water, respectively.

As the amount of water increases, the viscosity decreases, which conforms to the reaction principle. The vesicles are water-absorbent, and the viscosity of the 20g water premix is good in batch stability.

Table 3 The influence of the amount of silicone oil added on the viscosity of the premix

The more silicone oil is added, the lower the viscosity of the premix. The viscosity of E-1 and E-2 is too high, and E-3, E-4, and E-5 gradually decrease, preferably E-3, with a vesicle content of 20.0%.

Table 4 The effect of the amount of catalyst added on the viscosity of the premix

In Table 4, in different Examples E-16, E-17, E-18, E-19, E-20, the catalysts are tetramethylammonium hydroxide, lithium hydroxide, potassium hydroxide, and sodium hydroxide. , Tetramethylammonium hydroxide.

The catalyst dosage is large and the processing speed is fast, but the post-processing is time-consuming and energy-consuming. Considering the equipment efficiency, E-3 has a better effect.

In the above embodiment, the vesicle is a continuous aggregate of mesoporous silica vesicles, the size of the continuous vesicle is 20～100nm, the thickness of the pore wall is 4～6nm, the pore size distribution is hierarchical pores, and the gap between the walls is 2 ～4nm, vesicle pore size 20～40nm, specific surface area is 600～1100m2/g; density is about 40kg/m3; high temperature performance is stable at 850℃, pore structure remains intact under 10MPa pressure.

The second part: the formulation optimization design of the addition-molded liquid foamed silicone rubber.

In the second part of the embodiments, the embodiment E-18 is taken as a representative, and the other groups also have their own characteristics, which will not be repeated here.

Add the premix, platinum catalyst, inhibitor and hydrogen-containing silicone oil in sequence in the mixer, stir evenly and degas quickly, pour it into a mold, and let it stand for observation at room temperature. Start to foam until the surface is not sticky and the volume of the sponge is stable.

According to the above method, the corresponding components are respectively added in the following examples.

Table 5 The influence of premix and platinum addition on foaming ratio and thermal conductivity

Note: The concentration of platinum catalyst is 5000ppm; the inhibitor is 1.0% of methylbutynol.

In Table 5, in different Examples E-19, E-20, E-21, E-22, E-23, E-24, E-25, E-26, E-27, the platinum catalyst is: chlorine Platinum acid; inhibitors are: tetramethyldivinyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, methylbutynol, tetramethyldivinyldisiloxane, ethynyl Cyclohexanol, phosphite, unsaturated amide, maleate, methyl butynol.

Increasing the ratio of premix to platinum will increase the ratio of vesicles and increase the expansion ratio, which is beneficial to reduce the thermal conductivity.

Table 6 The influence of premix and hydrogen-containing siloxane addition on foaming ratio and thermal conductivity

Increasing the proportion of hydrogen-containing siloxane, the active hydroxyl groups of the premix will react fully, the amount of gas will be large, and the foaming ratio of the silicone rubber body will increase, which is beneficial to reduce the thermal conductivity to 0.34w/m.k.

In the foregoing embodiments, except for the viscosity unit, the component units are all parts by mass.

The foregoing embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

The synergistic premix for continuous aggregates of in-situ grafted modified mesoporous silica vesicles is characterized by comprising the following components by mass:
The in-situ graft-modified mesoporous silica vesicle continuous aggregate synergistic premix according to claim 1, characterized in that: the (A) terminal vinyl silicone oil is vinyl terminal silicone Alkane has a viscosity of 5000 to 200000 mPa.s, and its side chain is a methyl group or a combination of a methyl group and a phenyl group.
The in-situ graft-modified mesoporous silica vesicle continuous aggregate synergistic premix according to claim 1, characterized in that: the (A) terminal vinyl silicone oil has a mass part of 2000.0.
The in-situ graft-modified mesoporous silica vesicle continuous aggregate synergistic premix according to claim 1, characterized in that: the (C) basic catalyst is lithium hydroxide, potassium hydroxide , Sodium hydroxide, tetramethylammonium hydroxide or a balance of potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide and siloxane.
The in-situ graft-modified mesoporous silica vesicle continuous aggregate synergistic premix according to claim 4, characterized in that: the (C) basic catalyst is tetramethylammonium hydroxide.
The synergistic premix for continuous aggregates of in-situ grafted modified mesoporous silica vesicles according to claim 1, wherein the (D) vesicles are continuous mesoporous silica vesicles. Aggregates.
The in-situ grafted modified mesoporous silica vesicle continuous aggregate synergistic silicone rubber sponge thermal insulation material using the premix of any one of claims 1-6 is characterized in that it comprises the following components by mass :
The in-situ graft-modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge thermal insulation material according to claim 7, characterized in that: the (F) platinum catalyst is chloroplatinic acid, three Phenylphosphine platinum, alcohol or ether complexes of chloroplatinic acid, alkenyl complexes of platinum.
The in-situ graft-modified mesoporous silica vesicle continuous aggregate synergistic silicone rubber sponge heat insulation material according to claim 8, wherein the (F) platinum catalyst is an alkenyl complex of platinum Things.
The in-situ grafted modified mesoporous silica vesicle continuous aggregate synergistic silicone rubber sponge thermal insulation material according to claim 8 or 9, characterized in that the alkenyl complex in the platinum alkenyl complex The ligand is an olefin, vinyl siloxane or tetramethyldivinyl disiloxane.
The in-situ grafted modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge thermal insulation material according to claim 8 or 9, characterized in that: the platinum alkenyl complex is diethylene Tetramethyldisiloxane platinum complex and tetramethyltetravinylcyclotetrasiloxane platinum complex.
The in-situ graft-modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge heat insulation material according to claim 7, wherein the (G) inhibitor is vinyl siloxane , Acetylenic alcohol, phosphite, unsaturated amide or maleate.
The in-situ grafted modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge heat insulation material according to claim 12, characterized in that: the (G) inhibitor is vinyl siloxane Or acetylenic alcohol.
The in-situ grafted modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge heat insulation material according to claim 7, characterized in that: the (I) hydrogen-containing siloxane is cyclic , Linear or branched hydrogen-containing siloxane.
The in-situ graft-modified mesoporous silica vesicle continuous aggregate synergistic silicone rubber sponge thermal insulation material according to claim 7, characterized in that: (I) the viscosity of the hydrogen-containing siloxane ( 25°C) is 10.0～50.0mPa.s.
The in-situ graft-modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge heat insulation material according to claim 15, characterized in that: (I) the viscosity of the hydrogen-containing siloxane ( 25°C) is 20.0～30.0mPa.s.
The in-situ grafted modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge thermal insulation material according to claim 7, characterized in that: the hydrogen-containing hydrogen of the (I) hydrogen-containing siloxane The amount is 0.1 to 1.67%.
The in-situ grafted modified mesoporous silica vesicle continuous aggregates synergistic silicone rubber sponge thermal insulation material according to claim 17, characterized in that: the (I) hydrogen-containing hydrogen-containing siloxane The amount is 1.5% to 1.6%.
The in-situ graft modification method of continuous aggregates of mesoporous silica vesicles is characterized in that: (A) terminal vinyl silicone oil, (B) water and (D) vesicles are used as raw materials, and (C) alkaline A premix is formed under the action of a catalyst; in the premix, a hydroxyl-terminated polysiloxane is produced in situ under the action of (C) alkaline catalyst, and a part of the hydroxyl-terminated polysiloxane reacts with active hydroxyl groups and vesicles The silanol on the surface is condensed to form a graft modification; another part of the hydroxy-terminated polysiloxane is dissolved in the premix; the premix contains the following components by mass:
The preparation method of the in-situ grafted modified mesoporous silica vesicle continuous aggregate synergistic silicone rubber sponge heat insulation material is characterized in that it comprises the following steps:

(1) Using (A) terminal vinyl silicone oil, (B) water and (D) vesicles as raw materials, (E) premixed material is formed under the action of (C) alkaline catalyst; (E) premixed material , Under the action of (C) alkaline catalyst, hydroxyl-terminated polysiloxane is produced in situ, and part of the reactive hydroxyl group of hydroxyl-terminated polysiloxane condenses with the silanol on the surface of the vesicle to form graft modification; the other part Hydroxy-terminated polysiloxane is dissolved in (E) premix; said (E) premix contains the following components by mass:

(2) Add (E) premix, (F) platinum catalyst, (G) inhibitor, (H) terminal vinyl silicone oil and (I) hydrogen-containing siloxane in sequence, stir evenly and defoam quickly, and pour it into the mold Start to foam until the surface is not sticky and the sponge volume is stable, the (E) premix, (F) platinum catalyst, (G) inhibitor, (H) terminal vinyl silicone oil and (I) hydrogen-containing silicon The mass parts of oxane are: