1. A durable liquid silica gel is characterized by comprising the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 40-60 parts of vinyl silicone oil with vinyl-terminated side chain and 0.2-0.6 part of organic tin by mass; the component B is prepared by 40-60 parts of vinyl-terminated side chain vinyl silicone oil, 1-5 parts of ethyl orthosilicate, 1-4 parts of polyethylene glycol, 0.5-1.2 parts of gamma-aminopropyltriethoxysilane, 0.25-0.45 part of modified sodium bicarbonate and 15-20 parts of hydrogen-containing silicone oil;

the preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass portion, vacuumizing and drying at the temperature of 100-150 ℃ for 24-36 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and hermetically cooling to 25 ℃;

(2) putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst of organotin according to the mass part, stirring for 30-60min at the stirring frequency of 50Hz to obtain a component A product;

the preparation method of the component B comprises the following steps: carrying out vacuum drying on the vinyl-terminated side chain vinyl silicone oil at the temperature of 100-150 ℃ for 24-36h, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and carrying out closed cooling to 25 ℃; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 15-20 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

2. The durable liquid silicone gum according to claim 1, wherein the component A is formulated from 50 parts by mass of a vinyl-terminated side chain vinyl silicone oil and 0.4 parts by mass of an organotin; the component B is prepared from 50 parts of vinyl-terminated side chain vinyl silicone oil, 3 parts of ethyl orthosilicate, 3 parts of polyethylene glycol, 0.8 part of gamma-aminopropyltriethoxysilane, 0.35 part of modified sodium bicarbonate and 18 parts of hydrogen-containing silicone oil.

3. The durable liquid silicone gel of claim 1, wherein the modified sodium bicarbonate is prepared by: pouring sodium bicarbonate and zirconia ball milling beads into a ball milling tank to prepare sodium bicarbonate powder; pouring stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill with the rotation speed of 250-350r/min, and then placing the mixture in a forced air drying oven at 45 ℃ to evaporate the absolute ethyl alcohol to obtain the modified sodium bicarbonate.

4. The durable liquid silicone gel of claim 3, wherein the mass ratio of sodium bicarbonate to stearic acid is (8-12): (0.8-1.2), and the mass ratio of zirconia ball milling beads to sodium bicarbonate + stearic acid is (4-6): (0.7-1.5).

5. The durable liquid silicone gel of claim 4, wherein the mass ratio of sodium bicarbonate to stearic acid is 10:1, and the mass ratio of zirconia balls is 5: 1.

6. A method of preparing a long-lasting, durable liquid silica gel according to any one of claims 1 to 5, comprising the steps of: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

Background

The liquid rubber is a novel silica gel developed in the last 70 th century, and is a kind of silica gel with a higher middle grade. Compared with other types of silica gel, the liquid silica gel is convenient to use, generally does not need complex and large-scale processing equipment, can be processed by adopting the modes of coating, injection, extrusion and the like, and is vulcanized and molded at room temperature or under the heating condition. Compared with a thermally vulcanized silica gel material, the processing procedures of mixing, matching with a vulcanizing agent, tabletting, post-vulcanization and the like can be omitted, the energy is saved, the labor input is reduced, the production efficiency is high, the processing period is short, and the processing cost is low. At present, liquid silica gel is widely applied in the fields of biomedicine, aerospace, electronic components, automobile parts, sealing and filling materials, clothes and the like. Meanwhile, with the improvement of the performance requirements of the materials, the single liquid silica gel material is difficult to meet the requirements of production and application, so that a great deal of modification research is carried out on the liquid silica gel material in the past decades. Various functional liquid silica gels, such as heat-conducting liquid silica gels, conductive liquid silica gels, flame-retardant liquid silica gels, heat-resistant liquid silica gels, wave-absorbing silica gels and other special or functional silica gels, have the advantages of excellent performance, simple and convenient processing conditions and the like, are gradually developed, so that the liquid silica gels are paid more and more attention and are applied, the demand on the liquid silica gels is higher and higher, and the liquid silica gels are in a rapidly-developing era.

Liquid silicone rubber is widely used for potting and bonding electronic components due to excellent high and low temperature performance and electrical insulation performance. Especially, the addition type silica gel has the characteristics of no volatilization in reaction and low shrinkage in solidification, and is favored by the broad masses of users. However, the existing liquid silica gel has high viscosity and low activity, or has low viscosity and high activity; the liquid silica gel with high viscosity and low activity is not beneficial to the filling procedure because of larger intermolecular binding force, thereby causing the defect of low filling efficiency; and the liquid silica gel with low viscosity and high activity has the defects of low tensile strength and low stretch-break ratio after solidification due to the small intermolecular binding force.

Chinese patent document ZL201110445014.0 discloses a transparent liquid silica gel which uses hydroxyl-terminated polysiloxane and catalyst as component A, hydroxyl-terminated polysiloxane and cross-linking agent as component B, low molecular weight polyethylene glycol is added into component B as stabilizer to ensure the stability and transparency of the product, aminopropyltriethoxysilane and epoxypropyltrimethoxysilane are added as auxiliary curing agent to accelerate the deep curing of the silica gel, the component A is prepared from 90-120 parts of hydroxyl-terminated polysiloxane and 1-3 parts of organic tin by mass, the component B is prepared from 90-120 parts of hydroxyl-terminated polysiloxane, 5-12 parts of ethyl orthosilicate, 2-5 parts of polyethylene glycol, 2-5 parts of aminopropyltriethoxysilane and 2-5 parts of epoxypropyltrimethoxysilane, A. the component B is mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then is directly used, and the molecular weight of the polyethylene glycol is 200-600. The liquid silica gel disclosed by the invention has the characteristics of low viscosity, high transparency and high curing speed, but still has the problem of poor mechanical property.

Disclosure of Invention

The invention aims to provide a preparation method of durable liquid silica gel, which aims to solve the problem of how to optimize components, dosage, process and the like and improve the mechanical property of the liquid silica gel on the basis of the disclosure of Chinese patent document ZL 201110445014.0.

In order to solve the technical problems, the invention adopts the following technical scheme:

a durable liquid silica gel comprises the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 40-60 parts of vinyl silicone oil with vinyl-terminated side chain and 0.2-0.6 part of organic tin by mass; the component B is prepared from 40-60 parts of vinyl-terminated side chain vinyl silicone oil, 1-5 parts of ethyl orthosilicate, 1-4 parts of polyethylene glycol, 0.5-1.2 parts of gamma-aminopropyltriethoxysilane, 0.25-0.45 part of modified sodium bicarbonate and 15-20 parts of hydrogen-containing silicone oil.

Preferably, the component A is prepared from 50 parts of vinyl-terminated side chain vinyl silicone oil and 0.4 part of organic tin in parts by mass; the component B is prepared from 50 parts of vinyl-terminated side chain vinyl silicone oil, 3 parts of ethyl orthosilicate, 3 parts of polyethylene glycol, 0.8 part of gamma-aminopropyltriethoxysilane, 0.35 part of modified sodium bicarbonate and 18 parts of hydrogen-containing silicone oil.

Preferably, the preparation method of the modified sodium bicarbonate comprises the following steps: pouring sodium bicarbonate and zirconia ball milling beads into a ball milling tank to prepare sodium bicarbonate powder; pouring stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill with the rotation speed of 250-350r/min, and then placing the mixture in a forced air drying oven at 45 ℃ to evaporate the absolute ethyl alcohol to obtain the modified sodium bicarbonate.

Preferably, the mass ratio of the sodium bicarbonate to the stearic acid is (8-12): (0.8-1.2), and the mass ratio of the zirconia ball milling beads to the sodium bicarbonate + stearic acid is (4-6): (0.7-1.5).

Preferably, the mass ratio of the sodium bicarbonate to the stearic acid is 10:1, and the mass ratio of the zirconia ball milling beads to the sodium bicarbonate + the stearic acid is 5: 1.

Preferably, the preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass portion, vacuumizing and drying at the temperature of 100-150 ℃ for 24-36 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and hermetically cooling to 25 ℃;

(2) and putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst of organotin according to the mass part, stirring for 30-60min at the stirring frequency of 50Hz, and thus obtaining the component A.

Preferably, the preparation method of the component B comprises the following steps: carrying out vacuum drying on the vinyl-terminated side chain vinyl silicone oil at the temperature of 100-150 ℃ for 24-36h, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and carrying out closed cooling to 25 ℃; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 15-20 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

A method for preparing durable liquid silica gel, comprising the following steps: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

The invention has the following beneficial effects:

according to the invention, the hydrogen-containing silicone oil in the raw materials is used as a cross-linking agent, the addition of the hydrogen-containing silicone oil directly influences the cross-linking density of the colloid, the liquid silica gel matrix is obtained by cross-linking and vulcanizing the cross-linking agent hydrogen-containing silicone oil and the vinyl-terminated side chain vinyl silicone oil, and after the addition of the cross-linking agent, the polymer cross-linking network structure is enhanced, the vulcanization strength is improved, so that the final colloid physical properties are improved, namely the tensile strength, the tensile elongation at break and the hardness are improved and enhanced.

The surface of the liquid silica gel contains-OH groups which can be reacted with-OCH of gamma-aminopropyltriethoxysilane molecules₂CH₃The group is subjected to substitution reaction, so that gamma-aminopropyltriethoxysilane molecules are grafted on the surface of the liquid silica gel, the surface of the liquid silica gel is hydrophobic, the dispersibility of the liquid silica gel is improved, and the occurrence of agglomeration is reduced. Meanwhile, the gamma-aminopropyltriethoxysilane can enhance the interface bonding force of the liquid silica gel. The reason is that the surface of the liquid silica gel treated by the gamma-aminopropyltriethoxysilane coupling agent is successfully grafted with a molecular chain of the coupling agent, and the interface bonding property and the dispersion property of the liquid silica gel are enhanced through the connection effect of the coupling molecules, so that the vulcanization of the silica gel is facilitated, and the mechanical property is improved.

When the modified sodium bicarbonate is used as a foaming agent, the sodium bicarbonate is dispersed in the liquid silica gel in the form of small solid particles, so that the sodium bicarbonate particles themselves play the role of bubble nuclei in the decomposition process, and gas generated by the decomposition is gathered around the sodium bicarbonate particles. In the foaming process, when the foaming agent is continuously decomposed, gas dissolved in the colloid can gradually migrate into the air holes to reach a saturated state, the gas pressure is increased and the gas is expanded outwards, so that the hole walls are deformed to generate holes, then the viscosity and the surface tension of the colloid are gradually increased to play a stabilizing role in the foam holes, and the foam holes are generated. When stearic acid is used as a modifier to modify sodium bicarbonate, stearic acid and sodium bicarbonate are interacted, stearic acid has an activating effect on sodium bicarbonate, and when stearic acid and sodium bicarbonate coexist, sodium bicarbonate is a heat absorption type foaming agent and can absorb a large amount of heat, so that the melting decomposition temperature of stearic acid is increased. The stearic acid is added, so that the initial decomposition temperature of the sodium bicarbonate is increased, the decomposition temperature interval is shortened, the weight loss rate of the sodium bicarbonate is reduced, the foaming rate of the sodium bicarbonate is increased, the gas evolution rate of the sodium bicarbonate is increased, the viscosity of the sodium bicarbonate is matched with the viscosity of the liquid silica gel, and the pores are smoothly foamed in the liquid silica gel.

Detailed Description

For a better understanding of the present invention, the following examples are given to illustrate, but not to limit the scope of the present invention.

In the following examples, the durable liquid silicone gum comprises the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 40-60 parts of vinyl silicone oil with vinyl-terminated side chain and 0.2-0.6 part of organic tin by mass; the component B is prepared from 40-60 parts of vinyl-terminated side chain vinyl silicone oil, 1-5 parts of ethyl orthosilicate, 1-4 parts of polyethylene glycol, 0.5-1.2 parts of gamma-aminopropyltriethoxysilane, 0.25-0.45 part of modified sodium bicarbonate and 15-20 parts of hydrogen-containing silicone oil.

The preparation method of the modified sodium bicarbonate comprises the following steps: pouring 8-12 parts of sodium bicarbonate and 44-66 grinding beads of zirconia balls into a ball milling tank to prepare sodium bicarbonate powder; pouring 0.8-1.2 parts of stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill with the rotation speed of 250-350r/min, and then placing the mixture in a forced air drying oven at 45 ℃ to evaporate the absolute ethyl alcohol to obtain the modified sodium bicarbonate.

The preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass portion, vacuumizing and drying at the temperature of 100-150 ℃ for 24-36 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and hermetically cooling to 25 ℃;

(2) and putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst of organotin according to the mass part, stirring for 30-60min at the stirring frequency of 50Hz, and thus obtaining the component A.

The preparation method of the component B comprises the following steps: carrying out vacuum drying on the vinyl-terminated side chain vinyl silicone oil at the temperature of 100-150 ℃ for 24-36h, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and carrying out closed cooling to 25 ℃; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 15-20 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

A method for preparing durable liquid silica gel, comprising the following steps: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

Example 1

A durable liquid silica gel comprises the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 50 parts of terminal vinyl side chain vinyl silicone oil and 0.4 part of organic tin in parts by mass; the component B is prepared from 50 parts of vinyl-terminated side chain vinyl silicone oil, 3 parts of ethyl orthosilicate, 3 parts of polyethylene glycol, 0.8 part of gamma-aminopropyltriethoxysilane, 0.35 part of modified sodium bicarbonate and 18 parts of hydrogen-containing silicone oil.

The preparation method of the modified sodium bicarbonate comprises the following steps: pouring 10 parts of sodium bicarbonate and 55 grinding beads of zirconia balls into a ball milling tank to prepare sodium bicarbonate powder; pouring 1 part of stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill at the rotating speed of 300r/min, then placing the mixture in a forced air drying oven at 45 ℃ to evaporate the anhydrous ethanol, thus obtaining the modified sodium bicarbonate.

The preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass portion, vacuumizing and drying at 120 ℃ for 24-36 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and sealing and cooling to 25 ℃;

(2) and putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst of organotin according to the mass part, stirring for 40min, and stirring at the frequency of 50Hz to obtain the component A.

The preparation method of the component B comprises the following steps: vacuum-drying vinyl-terminated side chain vinyl silicone oil at 120 deg.C for 30h with relative vacuum degree of 0.1 Mpa or more, and sealing and cooling to 25 deg.C; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 18 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

A method for preparing durable liquid silica gel, comprising the following steps: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

Example 2

A durable liquid silica gel comprises the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 60 parts of vinyl-terminated side chain vinyl silicone oil and 0.2 part of organic tin in parts by mass; the component B is prepared from 60 parts of vinyl-terminated side chain vinyl silicone oil, 1 part of ethyl orthosilicate, 1-4 parts of polyethylene glycol, 1.0 part of gamma-aminopropyl triethoxysilane, 0.30 part of modified sodium bicarbonate and 17 parts of hydrogen-containing silicone oil.

The preparation method of the modified sodium bicarbonate comprises the following steps: pouring 11 parts of sodium bicarbonate and 60 grinding beads of zirconia balls into a ball milling tank to prepare sodium bicarbonate powder; pouring 1 part of stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill at the rotating speed of 350r/min, then placing the mixture in a forced air drying oven at 45 ℃ to evaporate the anhydrous ethanol, thus obtaining the modified sodium bicarbonate.

The preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass parts, vacuumizing and drying at 100 ℃ for 24 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and hermetically cooling to 25 ℃;

(2) and putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst of organotin according to the mass part, stirring for 30min, and stirring at the frequency of 50Hz to obtain the component A.

The preparation method of the component B comprises the following steps: vacuumizing and drying vinyl-terminated side chain vinyl silicone oil at 100 ℃ for 24 hours, keeping the relative vacuum degree to be more than or equal to 0.1 Mpa, and sealing and cooling to 25 ℃; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 20 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

A method for preparing durable liquid silica gel, comprising the following steps: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

Example 3

A durable liquid silica gel comprises the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 40 parts of terminal vinyl side chain vinyl silicone oil and 0.3 part of organic tin in parts by mass; the component B is prepared from 40 parts of vinyl-terminated side chain vinyl silicone oil, 3 parts of ethyl orthosilicate, 2 parts of polyethylene glycol, 1.2 parts of gamma-aminopropyl triethoxysilane, 0.45 part of modified sodium bicarbonate and 20 parts of hydrogen-containing silicone oil.

The preparation method of the modified sodium bicarbonate comprises the following steps: pouring 12 parts of sodium bicarbonate and 66 grinding beads of zirconia balls into a ball milling tank to prepare sodium bicarbonate powder; pouring 1.2 parts of stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill at the rotating speed of 250r/min, then placing the mixture in a forced air drying oven at 45 ℃ to evaporate anhydrous ethanol, thus obtaining the modified sodium bicarbonate.

The preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass parts, vacuumizing and drying at 130 ℃ for 28 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and hermetically cooling to 25 ℃;

(2) and putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst organotin according to the mass part, stirring for 50min, and stirring at the frequency of 50Hz to obtain the component A.

The preparation method of the component B comprises the following steps: vacuumizing and drying the vinyl-terminated side chain vinyl silicone oil at 130 ℃ for 28h, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and hermetically cooling to 25 ℃; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 15 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

A method for preparing durable liquid silica gel, comprising the following steps: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

Example 4

A durable liquid silica gel comprises the following raw materials: the preparation method comprises the following steps of taking vinyl-terminated side chain vinyl silicone oil and a catalyst as a component A, taking the vinyl-terminated side chain vinyl silicone oil and a cross-linking agent as a component B, adding low-molecular-weight polyethylene glycol as a stabilizing agent in the component B to ensure the stability and transparency of a product, and adding gamma-aminopropyltriethoxysilane, modified sodium bicarbonate and hydrogen-containing silicone oil;

the component A is prepared from 50 parts of terminal vinyl side chain vinyl silicone oil and 0.6 part of organic tin in parts by mass; the component B is prepared from 50 parts of vinyl-terminated side chain vinyl silicone oil, 5 parts of ethyl orthosilicate, 4 parts of polyethylene glycol, 0.5 part of gamma-aminopropyltriethoxysilane, 0.25 part of modified sodium bicarbonate and 15 parts of hydrogen-containing silicone oil.

The preparation method of the modified sodium bicarbonate comprises the following steps: pouring 8 parts of sodium bicarbonate and 44 grinding beads of zirconia balls into a ball milling tank to prepare sodium bicarbonate powder; pouring 0.8 part of stearic acid into a proper amount of absolute ethyl alcohol, stirring to fully dissolve the stearic acid in the absolute ethyl alcohol, and preparing a stearic acid solution; pouring the stearic acid solution into a ball milling tank, blending with sodium bicarbonate powder, ball milling for 2h in a ball mill with the rotating speed of 320r/min, then placing the mixture in a forced air drying oven at 45 ℃ to evaporate the absolute ethyl alcohol, thus obtaining the modified sodium bicarbonate.

The preparation method of the component A comprises the following steps:

(1) weighing vinyl-terminated side chain vinyl silicone oil according to the mass parts, vacuumizing and drying at 150 ℃ for 36 hours, wherein the relative vacuum degree is more than or equal to 0.1 Mpa, and sealing and cooling to 25 ℃;

(2) and putting the dried vinyl side chain-terminated vinyl silicone oil into a ball mill, adding a catalyst of organotin according to the mass part, stirring for 60min at the stirring frequency of 50Hz, and thus obtaining the component A.

The preparation method of the component B comprises the following steps: vacuum-drying vinyl-terminated side chain vinyl silicone oil at 150 deg.C for 36h with relative vacuum degree of 0.1 Mpa or more, and sealing and cooling to 25 deg.C; putting the dried vinyl-terminated side chain vinyl silicone oil, ethyl orthosilicate, polyethylene glycol, gamma-aminopropyl triethoxysilane and hydrogen-containing silicone oil into a container, fully stirring, adding modified sodium bicarbonate, and fully stirring again; and grinding the stirred mixture for 18 min by using a grinder at room temperature to uniformly disperse the modified sodium bicarbonate in the liquid silica gel to obtain a component B product.

A method for preparing durable liquid silica gel, comprising the following steps: the component A and the component B are mixed according to the proportion of 1:1, the volume ratio or the weight ratio and then are directly used.

Comparative example 1

The procedure was substantially the same as in example 1, except that gamma-aminopropyltriethoxysilane, modified sodium bicarbonate, hydrogen-containing silicone oil were absent from the starting material for preparing the durable liquid silica gel.

Comparative example 2

Essentially the same procedure as in example 1, except that gamma-aminopropyltriethoxysilane was absent from the starting material for the preparation of the durable liquid silica gel.

Comparative example 3

Essentially the same procedure as in example 1 was followed, except that the modified sodium bicarbonate was absent from the starting material used to prepare the durable liquid silica gel.

Comparative example 4

The procedure was substantially the same as in example 1 except that hydrogen-containing silicone oil was absent from the starting material for preparing the durable liquid silica gel.

Comparative example 5

The durable liquid silica gel was prepared by the method described in example 1 of the Chinese patent document "a transparent liquid silica gel and its preparation method (patent No. ZL 201110445014.0)".

The long-lasting, durable liquid silica gels of examples 1-4 and comparative examples 1-5 were subjected to relevant performance tests, the results of which are shown in the following table.

Item	Tensile Strength (MPa)	Elongation at Break (%)
			Example 1	24.8	680.1
Example 2	23.3	675.6
			Example 3	24.1	678.9
Example 4	22.8	677.2
			Comparative example 1	15.2	650.7
Comparative example 2	21.1	674.5
			Comparative example 3	22.3	673.6
Comparative example 4	21.8	672.1
			Comparative example 5	14.3	641.6

As can be seen from the data of examples 1-4 and comparative example 5 above, the tensile strength and elongation at break of the long-lasting, durable liquid silicone gum prepared in examples 1-4 is significantly greater than the tensile strength and elongation at break of the long-lasting, durable liquid silicone gum prepared in comparative example 5.

As can be seen from the data of example 1 and comparative examples 1-4 above, γ -aminopropyltriethoxysilane, modified sodium bicarbonate, and hydrogen-containing silicone oil act synergistically in preparing liquid silica gels to synergistically increase the tensile strength, tensile elongation at break, of the liquid silica gel because:

according to the invention, the hydrogen-containing silicone oil in the raw materials is used as a cross-linking agent, the addition of the hydrogen-containing silicone oil directly influences the cross-linking density of the colloid, the liquid silica gel matrix is obtained by cross-linking and vulcanizing the cross-linking agent hydrogen-containing silicone oil and the vinyl-terminated side chain vinyl silicone oil, and after the addition of the cross-linking agent, the polymer cross-linking network structure is enhanced, the vulcanization strength is improved, so that the final colloid physical properties are improved, namely the tensile strength, the tensile elongation at break and the hardness are improved and enhanced.

The surface of the liquid silica gel contains-OH groups which can be reacted with-OCH of gamma-aminopropyltriethoxysilane molecules₂CH₃The groups are subjected to substitution reactionThus, gamma-aminopropyltriethoxysilane molecules are grafted on the surface of the liquid silica gel, the surface of the liquid silica gel is hydrophobic, the dispersibility of the liquid silica gel is improved, and the occurrence of agglomeration is reduced. Meanwhile, the gamma-aminopropyltriethoxysilane can enhance the interface bonding force of the liquid silica gel. The reason is that the surface of the liquid silica gel treated by the gamma-aminopropyltriethoxysilane coupling agent is successfully grafted with a molecular chain of the coupling agent, and the interface bonding property and the dispersion property of the liquid silica gel are enhanced through the connection effect of the coupling molecules, so that the vulcanization of the silica gel is facilitated, and the mechanical property is improved.

When the modified sodium bicarbonate is used as a foaming agent, the sodium bicarbonate is dispersed in the liquid silica gel in the form of small solid particles, so that the sodium bicarbonate particles themselves play the role of bubble nuclei in the decomposition process, and gas generated by the decomposition is gathered around the sodium bicarbonate particles. In the foaming process, when the foaming agent is continuously decomposed, gas dissolved in the colloid can gradually migrate into the air holes to reach a saturated state, the gas pressure is increased and the gas is expanded outwards, so that the hole walls are deformed to generate holes, then the viscosity and the surface tension of the colloid are gradually increased to play a stabilizing role in the foam holes, and the foam holes are generated. When stearic acid is used as a modifier to modify sodium bicarbonate, stearic acid and sodium bicarbonate are interacted, stearic acid has an activating effect on sodium bicarbonate, and when stearic acid and sodium bicarbonate coexist, sodium bicarbonate is a heat absorption type foaming agent and can absorb a large amount of heat, so that the melting decomposition temperature of stearic acid is increased. The stearic acid is added, so that the initial decomposition temperature of the sodium bicarbonate is increased, the decomposition temperature interval is shortened, the weight loss rate of the sodium bicarbonate is reduced, the foaming rate of the sodium bicarbonate is increased, the gas evolution rate of the sodium bicarbonate is increased, the viscosity of the sodium bicarbonate is matched with the viscosity of the liquid silica gel, and the pores are smoothly foamed in the liquid silica gel.

The above description should not be taken as limiting the invention to the embodiments, but rather, as will be apparent to those skilled in the art to which the invention pertains, numerous simplifications or substitutions may be made without departing from the spirit of the invention, which shall be deemed to fall within the scope of the invention as defined by the claims appended hereto.