CN110903653A - Silicone rubber composition, silicone rubber and preparation method thereof - Google Patents
Silicone rubber composition, silicone rubber and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a silicon rubber composition, silicon rubber and a preparation method thereof. The silicone rubber composition comprises a base rubber and a microcapsule catalyst; wherein the microcapsule catalyst comprises a heated and melted organic silicon wax matrix and a hydrosilylation catalyst embedded in the organic silicon wax matrix. In the silicone rubber composition, the microcapsule catalyst can be uniformly dispersed. Moreover, the silicone rubber composition has long room temperature storage time, no solidification within 30 days, small viscosity change and prolonged operation time. And heating the silicon rubber composition to prepare the silicon rubber with the net structure. The hydrosilylation reaction is uniform in the preparation process, the curing time is short, and the utilization efficiency of the catalyst is high.
Description
Technical Field
The invention relates to the field of silicone rubber, in particular to a silicone rubber composition, silicone rubber and a preparation method thereof.
Background
At present, liquid silicone rubber is generally subjected to a hydrosilylation reaction under the action of a noble metal catalyst such as platinum, rhodium, palladium and the like to prepare silicone rubber. However, the noble metal catalyst used for the hydrosilylation reaction has very high catalytic activity and can catalyze the hydrosilylation reaction at room temperature. Therefore, a curing retarder is generally added during the reaction process, so that the curing retarder is stable at room temperature and can react after the temperature is increased. However, the commonly used curing retarders are electron-deficient olefins such as alkynols, dimethyl maleate, dimethyl fumarate, etc., which have a weak coordination ability with noble metal catalysts and thus can only retard the reaction rate, not prevent the hydrosilation reaction. When the temperature is higher than the boiling point of the curing retarder, the curing retarder volatilizes, the catalytic rate of the noble metal catalyst is rapidly accelerated, and the liquid silicone rubber is prepared into the silicone rubber through the hydrosilylation reaction. Therefore, the liquid silicone rubber needs to be added with a curing retarder in the reaction process, so that the reaction speed of the liquid silicone rubber at room temperature is slowed down, and the operation time of the liquid silicone rubber (up to 3 days at 20 ℃) is prolonged; on the other hand, the temperature is increased during the reaction process to enable the resin to be rapidly solidified (generally above 100 ℃).
To overcome this disadvantage, the catalyst may be microencapsulated to be stable at room temperature. Because the catalyst is isolated and cannot play a role in catalysis, the hydrosilylation reaction can be catalyzed to proceed only when the temperature rises and the catalyst is released, and the silicon rubber is obtained by crosslinking.
However, most of the current microcapsule catalysts use thermoplastic polymers as wall materials, and although the microcapsules soften and the catalyst can diffuse out when the temperature is raised to be higher than the glass transition temperature of the thermoplastic polymers, the diffusion speed of the catalyst in the organosilicon with high viscosity is slow, so that the curing speed is slow for systems requiring fast curing (such as injection molding of liquid silicone rubber). Secondly, the thermoplastic polymer and the organic silicon have poor compatibility, the catalyst can only be dispersed by the diffusion action, and the diffused catalyst can rapidly catalyze the hydrosilation reaction to obtain the silicon rubber, so that the periphery of the microcapsule is solidified, the catalyst can not be continuously diffused, and the utilization rate of the catalyst is low.
Disclosure of Invention
Therefore, it is necessary to provide a silicone rubber composition, a silicone rubber and a preparation method thereof aiming at the preparation problem of the silicone rubber, wherein the microcapsule catalyst in the silicone rubber composition is uniformly dispersed, and in the preparation process, the silicone rubber composition can be rapidly catalyzed to perform a hydrosilylation reaction to prepare the silicone rubber after the microcapsule catalyst is heated to release the catalyst, and the utilization rate of the catalyst is high.
A silicone rubber composition comprising a base rubber and a microencapsulated catalyst;
wherein the microcapsule catalyst comprises a heated and melted organic silicon wax matrix and a hydrosilylation catalyst embedded in the organic silicon wax matrix.
In one embodiment, the silicone wax matrix has a melting point of 50 ℃ to 80 ℃.
In one embodiment, the microencapsulated catalyst further comprises expanded microspheres embedded in the silicone wax matrix.
In one embodiment, the weight of the expanded microspheres is 0.1% to 3% of the weight of the silicone wax matrix.
In one embodiment, the expanded microspheres have an initial thermal expansion temperature of less than 100 ℃.
In one embodiment, the hydrosilylation catalyst contains a metal in an amount of 10ppm to 5000ppm in the microcapsule catalyst.
In one embodiment, the hydrosilylation catalyst includes at least one of a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, a zirconium-based catalyst, a cobalt-based catalyst, and a nickel-based catalyst.
In one embodiment, the base rubber comprises raw rubber and a cross-linking agent, wherein the cross-linking agent is used in an amount of 10 to 30 parts by weight based on 100 parts by weight of the raw rubber, the microcapsule catalyst is used in an amount of 10 parts by weight based on the metal, and the metal is used in an amount of 10 parts by weight based on the metal-4Parts by weight-5X 10-2And (4) parts by weight.
In one embodiment, the raw rubber comprises vinyl-containing polysiloxane, the cross-linking agent comprises organohydrogenpolysiloxane, and the molar ratio of silicon hydrogen bonds in the organohydrogenpolysiloxane to vinyl groups in the vinyl-containing polysiloxane is (1-2): 1.
In one embodiment, the vinyl-containing polysiloxane has a viscosity of 0.1 pas to 1000 pas at 25 ℃; and/or
The viscosity of the organohydrogenpolysiloxane at 25 ℃ is 0.5 mPas to 10000 mPas.
In the silicone rubber composition, the microcapsule catalyst can be uniformly dispersed. In addition, in the microcapsule catalyst, the organic silicon wax matrix isolates the catalyst from the base rubber, so that the catalyst cannot play a role of catalysis, therefore, no curing retarder is required to be added into the silicone rubber composition, the silicone rubber composition has long room-temperature storage time, is not cured within 30 days, has small viscosity change, and can prolong the operation time.
A preparation method of silicone rubber comprises the following steps:
providing the above silicone rubber composition;
and heating the silicon rubber composition to obtain the silicon rubber.
In one embodiment, the maximum temperature of the heating is 50 ℃ to 200 ℃ and is higher than the melting point of the silicone wax matrix.
In one embodiment, the maximum temperature of the heating is above the initial thermal expansion temperature of the expanded microspheres.
In the preparation method of the silicone rubber, the microcapsule catalyst can be uniformly dispersed in the silicone rubber composition, so that the released catalyst can be uniformly dispersed in the silicone rubber composition after heating, thereby ensuring uniform hydrosilylation reaction, shortening curing time and improving reaction effect. Meanwhile, the over-high concentration of the local catalyst can be avoided, the dosage of the catalyst is reduced, and the utilization efficiency of the catalyst is improved.
The silicone rubber is obtained by the preparation method, and has a net structure.
The silicon rubber has the performances of heat resistance, cold resistance, dielectricity, ozone resistance, atmospheric aging resistance and the like, can be used for a long time at the temperature of minus 60 ℃ to 250 ℃, and can be widely applied to the fields of electronic packaging, medical appliances, consumer goods and the like.
Drawings
FIG. 1 is an electron micrograph of a microcapsule catalyst of example 1 of the present invention.
Detailed Description
The silicone rubber composition, the silicone rubber and the preparation method thereof provided by the invention will be further explained below.
The silicone rubber composition provided by the invention comprises a base rubber and a microcapsule catalyst; wherein the microcapsule catalyst comprises a heated and melted organic silicon wax matrix and a hydrosilylation catalyst embedded in the organic silicon wax matrix.
The organic silicon wax matrix has good compatibility with the base rubber, so that the microcapsule catalyst can be uniformly dispersed in the base rubber to form the silicon rubber composition.
Specifically, the melting point of the organic silicon wax matrix is 50-80 ℃. So that the microcapsule catalyst can release the catalyst below 100 deg.c and the reaction can be performed at relatively low temperature.
Specifically, the silicone wax is a long-chain alkyl (C)8The organic silicon wax is prepared by performing hydrosilylation reaction on an organic substance with a double bond at the end group and hydrogen-containing silicone oil under the catalysis of a catalyst such as platinum, and the like, wherein the organic substance with the double bond at the end group comprises α -olefin with more than 16 carbon atoms, alkyl carboxylic acid with a double bond at the end group, alkyl carboxylic ester with a double bond at the end group and polyethylene glycol with a double bond at the end group.
Specifically, the microcapsule catalyst further comprises expanded microspheres, and the expanded microspheres are embedded in the organic silicon wax matrix. After the expanded microspheres are heated and expanded, the volume is increased, and the diffusion of the microcapsule catalyst in the silicone rubber composition can be accelerated, so that the effect of assisting the diffusion of the catalyst is achieved. Furthermore, the silicon hydrogenation reaction in the silicon rubber composition is more uniform, the curing of the reaction is shortened, and the reaction effect is improved. Meanwhile, the over-high concentration of the local catalyst can be avoided, the dosage of the catalyst is reduced, and the utilization efficiency of the catalyst is improved.
Considering that the amount of the expanded microspheres is too small, the volume is not increased much after expansion, the effect is not obvious, and when the amount of the expanded microspheres is too large, the volume of the product is expanded too much in the forming process, so that the forming and mechanical properties of the product are influenced. Therefore, the weight of the expanded microspheres in the microcapsule catalyst is 0.1-3% of the weight of the organic silicon wax matrix.
Specifically, the initial thermal expansion temperature of the expanded microspheres is less than 100 ℃. Therefore, the microcapsule catalyst can be assisted to catalyze the silicone rubber composition to carry out the hydrosilation reaction at a lower temperature.
The expanded microsphere is common expanded microsphere, such as F-20, F-30, F-36, MSL-3030, F-48, etc. of Japanese pine oil, Expancel of AcksonobelTMExpanded microspheres, and the like.
Specifically, the hydrosilylation catalyst contains a metal, and the content of the metal in the microcapsule catalyst is 10ppm to 5000 ppm.
Specifically, the hydrosilylation catalyst includes at least one of a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, a zirconium-based catalyst, a cobalt-based catalyst, and a nickel-based catalyst.
The hydrosilylation catalyst is preferably a platinum-based catalyst such as platinum black, platinum chloride, a reactant of chloroplatinic acid and a monohydric alcohol, a complex of olefins, platinum bisacetoacetate, or the like, in view of the catalytic efficiency of the catalyst. Further, the platinum group catalyst is preferably chloroplatinic acid or Karstedt's catalyst (kastedt catalyst). Wherein the Karstedt catalyst is a platinum (0) complex of divinyltetramethyldisiloxane.
Specifically, the preparation method of the microcapsule catalyst comprises the following steps:
mixing organic silicon wax with an organic solvent, heating to melt the organic silicon wax, and adding a hydrosilylation catalyst to obtain a mixed solution;
b, providing a dispersing solution, wherein the dispersing solution comprises a dispersing agent and water, adding the mixed solution into the dispersing solution to disperse the mixed solution into the dispersing solution, and cooling to obtain a microcapsule catalyst suspension;
and c, separating the microcapsule catalyst suspension to obtain the microcapsule catalyst.
In the step a, the melting point of the organic silicon wax is 50-80 ℃. The organic solvent comprises at least one of alkane, ketone, ether and ester. The mass ratio of the organic solvent to the organic matter is 1: 2-2: 1.
The hydrosilylation catalyst includes at least one of a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, a zirconium-based catalyst, a cobalt-based catalyst, and a nickel-based catalyst, and is preferably a platinum-based catalyst. Further, the platinum group catalyst is preferably chloroplatinic acid or Karstedt's catalyst.
The hydrosilylation catalyst contains metal, and the content of the metal is 10ppm to 5000ppm of the weight of the organic silicon wax.
In the step b, the temperature of the dispersion solution is close to that of the mixed solution, so that the silicone wax is prevented from being separated out and solidified after the mixed solution is added into the dispersion solution.
Wherein the mass ratio of the dispersing agent to the water in the dispersion solution is as follows: (0.01-5): 100. The mass ratio of the mixed solution to the water in the dispersion solution is 1 (1-5).
Specifically, the dispersant comprises at least one of an organic dispersant and an inorganic dispersant. The dispersant is a common dispersant used for suspension polymerization and comprises at least one of an organic dispersant and an inorganic dispersant. The organic dispersant comprises at least one of polyvinyl alcohol, cellulose, gelatin, polyvinylpyrrolidone, calcium hydroxy phosphate, maleic anhydride-styrene copolymer and salt thereof, maleic anhydride-vinyl acetate copolymer and salt thereof, itaconic acid-styrene copolymer and salt thereof, itaconic acid-vinyl acetate copolymer and salt thereof, acrylic acid (salt) copolymer and methacrylic acid (salt) copolymer. The inorganic dispersant comprises at least one of magnesium hydroxide, basic magnesium carbonate, nano-silica, silica sol, kaolin and calcium sulfate.
Specifically, the mixed solution is added into the dispersion liquid, after the mixed solution is dispersed and stirred for a period of time at a high speed, the mixed solution is dispersed in water in the form of micro droplets, after the temperature is reduced, the silicone wax is solidified, and after the temperature is reduced to the room temperature, a microcapsule catalyst suspension is formed.
Before the step b, adding the mixed solution into the dispersion solution, adding expanded microspheres into the mixed solution.
Specifically, the mass ratio of the expanded microspheres to the organic silicon wax is (0.1-3): 100. The expanded microspheres have an initial thermal expansion temperature of less than 100 ℃.
In step c, the step of separating the microcapsule catalyst from the microcapsule catalyst suspension comprises filtering, washing and drying, and the obtained microcapsule catalyst is spherical particles with the particle size of tens of microns.
Specifically, after filtration, the filtrate is washed with an alcohol solvent and a hydrocarbon solvent in sequence, the hydrosilylation catalyst, the expanded microspheres and the like on the surface are removed, and the microcapsule catalyst powder is obtained after drying at room temperature.
The microcapsule catalyst has simple preparation method, easy operation, no need of other special reaction conditions and raw materials, and easy industrialization.
Specifically, the base gum comprises raw gum and a cross-linking agent. Considering that the catalyst efficiency is too low and the reaction speed is slow when the microcapsule catalyst is used in too small amount, and the cost is high when the microcapsule catalyst is used in too large amount. Preferably, the crosslinking agent is used in an amount of 10 to 30 parts by weight based on 100 parts by weight of the raw rubber, and the microcapsule catalyst is used in an amount of 10 parts by weight based on the metal-4Parts by weight-5X 10-2And (4) parts by weight.
Wherein the crude rubber comprises vinyl-containing polysiloxane, the vinyl-containing polysiloxane is polydiorganosiloxane containing two or more vinyl groups, and the structural formula of the raw rubber is as follows:
Y3-a-xPhx(CH3)aSiO[(CH3)2SiO]n[(CH3)RSiO]mSi(CH3)aPhxY3-a-x；
wherein Y is CH3-、CH2One of CH-is selected; r is CH2CH-、Ph-、CF3CH2CH2One of (1)(ii) a A is more than or equal to 0 and less than or equal to 3; x is 0 or 1; n is more than 0; m is more than or equal to 0; and a, n and m are integers.
The molecular weight of the vinyl-containing polysiloxane is not particularly limited, and the vinyl-containing polysiloxane may be any viscous substance having a low viscosity or a high viscosity and not having self-fluidity at room temperature.
Considering that when the viscosity is too low, the obtained silicone rubber has poor performance, and when the viscosity is too high, the processing and forming of the silicone rubber are not facilitated. Therefore, for the vinyl-containing polysiloxane having self-fluidity at room temperature, it is preferable that the viscosity of the vinyl-containing polysiloxane at 25 ℃ is 0.1 pas to 1000 pas.
The cross-linking agent comprises organohydrogenpolysiloxane, the organohydrogenpolysiloxane is organohydrogenpolysiloxane containing three or more than three silicon-hydrogen bonds (Si-H), and the structure of the organohydrogenpolysiloxane is as follows:
Ht(CH3)3-tSiO[(CH3)2SiO]b[(CH3)HSiO]cSi(CH3)3-tHt；
wherein t is more than or equal to 0 and less than or equal to 3, b is more than or equal to 0, and c is more than or equal to 2; and t, b and c are integers.
Preferably, the organohydrogenpolysiloxane has a viscosity of 0.5 to 10000 mPas at 25 ℃.
Considering that if the crosslinking is insufficient, the elastic properties of the silicone rubber are reduced; on the other hand, if the crosslinking is excessive, the mechanical strength after curing is deteriorated and the heat resistance and compression set are deteriorated. Preferably, the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is (1-2): 1.
preferably, the silicone rubber composition further comprises a reinforcing agent, and the mechanical property of the silicone rubber can be improved through the reinforcing agent.
Furthermore, the reinforcing agent is used in an amount of 10 to 40 parts by weight based on the weight of the raw rubber.
Further, the reinforcing agent is silicon dioxide. The silica has a BET specific surface area of 50m or more2A/g, preferably of 100m2/g～400m2/g。The silica is fumed silica or precipitated silica.
Further, the silica is treated with a surface treatment agent. The surface treatment agent comprises at least one of organopolysiloxane, silazane, chlorosilane and alkoxysilane.
Preferably, the silicone rubber composition further comprises at least one of a filler and an additive.
Further, the filler comprises white carbon black.
Further, the additive comprises at least one of pigment, heat-resistant additive, adhesion promoter, release agent and conductive agent.
Further, the pigment comprises TiO2、Fe2O3And carbon black. The heat-resistant additive comprises at least one of metal oxide and hydroxide. The adhesion promoter comprises at least one of a carbon-functional silane and a siloxane.
In the silicone rubber composition of the present invention, the microcapsule catalyst can be uniformly dispersed. In addition, in the microcapsule catalyst, the organic silicon wax matrix isolates the catalyst from the base rubber, so that the catalyst cannot play a role of catalysis, therefore, no curing retarder is required to be added into the silicone rubber composition, the silicone rubber composition has long room-temperature storage time, is not cured within 30 days, has small viscosity change, and can prolong the operation time.
The invention also provides a preparation method of the silicone rubber, which comprises the following steps:
s1, providing the above silicone rubber composition;
and S2, heating the silicon rubber composition to obtain the silicon rubber.
Specifically, the silicone rubber composition is heated, so that the organic silicone wax matrix of the microcapsule catalyst is melted, the hydrosilylation catalyst is released, and the base rubber is catalyzed to perform a crosslinking reaction to obtain the silicone rubber.
Specifically, the highest temperature of heating is 50-200 ℃, and is higher than the melting point of the organic silicon wax matrix. Thus, the silicone wax matrix can be melted to release the hydrosilylation catalyst.
Specifically, the maximum temperature of the heating is higher than the initial thermal expansion temperature of the expanded microspheres. Therefore, the expanded microspheres can be expanded by heating, the volume is increased, and the diffusion of the microcapsule catalyst in the silicone rubber composition can be accelerated, so that the effect of assisting the diffusion of the catalyst is achieved, and the preparation method is particularly suitable for injection molding of the silicone rubber composition.
In the preparation method of the silicone rubber, the microcapsule catalyst can be uniformly dispersed in the silicone rubber composition, so that the released catalyst can be uniformly dispersed in the silicone rubber composition after heating, thereby ensuring uniform hydrosilylation, shortening the curing time and improving the reaction effect. Meanwhile, the over-high concentration of the local catalyst can be avoided, the dosage of the catalyst is reduced, and the utilization efficiency of the catalyst is improved.
Secondly, the microcapsule catalyst can release the catalyst below 100 ℃, so that the hydrosilylation reaction can be carried out at a lower temperature, and further the preparation of the silicone rubber can be realized at a lower temperature.
Moreover, the microcapsule catalyst can be rapidly expanded at the reaction temperature, so that the microcapsule catalyst is rapidly dispersed in the silicone rubber composition, the effect of assisting in dispersing the catalyst is achieved, and the distribution of the catalyst of the liquid silicone rubber is more uniform.
The invention also provides silicon rubber which is obtained by the preparation method and has a net-shaped structure.
The silicon rubber has the performances of heat resistance, cold resistance, dielectricity, ozone resistance, atmospheric aging resistance and the like, can be used for a long time at the temperature of minus 60 ℃ to 250 ℃, and can be widely applied to the fields of electronic packaging, medical appliances, consumer goods and the like.
Hereinafter, the silicone rubber composition, the silicone rubber, and the preparation method thereof will be further described by the following specific examples.
Example 1:
heating 10g of organic silicon wax with the melting point of 50-52 ℃ and 5g of petroleum ether with the boiling point of 60-90 ℃ to 55 ℃ to obtain transparent and clear liquid. Adding 1g of Kaster catalyst (platinum content is 5000ppm) and 0.01g of turpentine oil F-20 expanded microspheres, and mixing uniformly to obtain a mixed solution a, wherein the temperature is maintained at about 55 ℃ to prevent organic silicon wax from being separated out.
0.1g of polyvinyl alcohol was added to 20g of water, and the mixture was dissolved by heating and stirring to obtain a solution b. Controlling the water temperature to be about 55 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 55 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
The microcapsule catalyst suspension was filtered, and the microcapsule catalyst particles obtained by the filtration were washed with ethanol, then washed with petroleum ether, and vacuum-dried for 3 hours to obtain a microcapsule catalyst as shown in fig. 1, as can be seen from fig. 1, the microcapsule catalyst was in the form of powder.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 2:
heating 10g of silicone wax with the melting point of 55-60 ℃ and 10g of petroleum ether with the boiling point of 60-90 ℃ to 60 ℃ to obtain transparent and clear liquid. 0.15g of Kaster catalyst (platinum content is 1000ppm) and 0.05g of turpentine oil F-36 expanded microspheres are added and mixed uniformly to obtain a mixed solution a. The temperature is maintained at about 58 ℃ to prevent the silicone wax from separating out.
0.1g of polyvinyl alcohol was added to 40g of water, and the mixture was dissolved by heating with stirring to obtain a solution b. Controlling the water temperature to be about 58 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 58 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with petroleum ether, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 3:
heating 10g of silicone wax with the melting point of 65-68 ℃ and 20g of petroleum ether with the boiling point of 60-90 ℃ to 65 ℃ to obtain transparent and clear liquid. 2.5g of Kaster catalyst (platinum content is 20000ppm) and 0.1g of turpentine oil F-36 expanded microspheres are added and mixed uniformly to obtain a mixed solution a. The temperature is maintained at about 65 ℃ to prevent the silicone wax from separating out.
0.1g of polyvinyl alcohol was added to 40g of water, and the mixture was dissolved by heating with stirring to obtain a solution b. Controlling the water temperature to be about 65 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 65 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with petroleum ether, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 4:
heating 10g of silicone wax with the melting point of 77-80 ℃ and 10g of toluene to 77 ℃ to obtain transparent and clear liquid. 1g of Kaster catalyst (with platinum content of 5000ppm) and 0.3g of turpentine oil F-48 expanded microspheres are added and mixed uniformly to obtain a mixed solution a. The temperature is maintained at about 77 ℃ to prevent the silicone wax from separating out.
0.2g of polyvinylpyrrolidone was added to 100g of water, and the mixture was dissolved by heating and stirring to obtain a solution b. Controlling the water temperature at about 77 ℃, pouring the mixed solution a into the solution b, stirring quickly, and stirring for 30 minutes at 77 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with petroleum ether, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 5:
heating 10g of organic silicon wax with the melting point of 50-52 ℃ and 5g of ethyl acetate to 55 ℃ to obtain transparent and clear liquid. Adding 1g of Kaster catalyst (platinum content is 5000ppm) and 0.1g of turpentine oil F-48 expanded microspheres, and uniformly mixing to obtain a mixed solution a. The temperature is maintained at about 55 ℃ to prevent the silicone wax from separating out.
0.1g of an alkaline silica sol (30%) was added to 20g of water, and the mixture was dissolved by heating with stirring to obtain a solution b. Controlling the water temperature to be about 55 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 55 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with hexane, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 6:
heating 10g of organic silicon wax with the melting point of 50-52 ℃ and 5g of butanone to 55 ℃ to obtain transparent and clear liquid. 0.2g chloroplatinic acid hexahydrate, 0.1g Acksonobel expanded microsphere ExpancelTM031DU40, mixing well to obtain mixed solution a. The temperature is maintained at about 55 ℃ to prevent the silicone wax from separating out.
0.1g of polyvinyl alcohol and 0.1g of magnesium hydroxide were added to 20g of water, and dissolved by heating with stirring. Controlling the water temperature to be about 55 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 55 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with hexane, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 7:
heating 10g of organic silicon wax with the melting point of 50-52 ℃ and 5g of ethyl acetate to 55 ℃ to obtain transparent and clear liquid. 0.5g of Co was added2(CO)80.3g of loose oil F-48 expanded microspheres, and uniformly mixing to obtain a mixed solution a. The temperature is maintained at about 55 ℃ to prevent the silicone wax from separating out.
0.1g of polyvinyl alcohol and 0.1g of calcium carbonate were added to 20g of water, and the mixture was dissolved by heating and stirring to obtain solution b. Controlling the water temperature to be about 55 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 55 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with hexane, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
Example 8:
heating 10g of organic silicon wax with the melting point of 50-52 ℃ and 5g of petroleum ether with the boiling point of 60-90 ℃ to 55 ℃ to obtain transparent and clear liquid. 2g of a Kaster catalyst (platinum content: 5000ppm) was added thereto and mixed well to obtain a mixed solution a. The temperature is maintained at about 55 ℃ to prevent the silicone wax from separating out.
0.1g of polyvinyl alcohol was added to 20g of water, and the mixture was dissolved by heating and stirring to obtain a solution b. Controlling the water temperature to be about 55 ℃, pouring the mixed solution a into the solution b, quickly stirring, and stirring for 30 minutes at 55 ℃. The temperature was reduced to 25 ℃ to obtain a suspension of the microencapsulated catalyst.
And filtering the microcapsule catalyst suspension, washing the microcapsule catalyst particles obtained by filtering with ethanol, washing with petroleum ether, and drying in vacuum for 3 hours to obtain the powdery microcapsule catalyst.
The platinum metal content in the microencapsulated catalyst was measured by inductively coupled plasma spectrometer (ICP) and the results are given in table 1.
TABLE 1
Example 9:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 335 pas at 25 ℃, 10 parts by weight of an organohydrogenpolysiloxane having a viscosity of 50 mPas at 25 ℃, and 20 parts by weight of an organohydrogenpolysiloxane having a BET specific surface area of 200m2(g) fumed silica and 2 parts by weight of the microcapsule catalyst obtained in example 1 were mixed to obtain a silicone rubber composition. Wherein, the molar ratio of the silicon-hydrogen bond in the organic hydrogen polysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1:1, and the content of the metal platinum is 9.8ppm of the silicon rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 10:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 740 pas at 25 ℃, 20 parts by weight of an organohydrogenpolysiloxane having a viscosity of 0.5 mPas at 25 ℃, and 10 parts by weight of an organopolysiloxane having a BET specific surface area of 400m2(g) fumed silica and 10 parts by weight of the microcapsule catalyst obtained in example 2 were mixed to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.2:1, and the content of the metal platinum is 1ppm of the silicone rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 11:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 60 pas at 25 ℃, 12 parts by weight of an organohydrogenpolysiloxane having a viscosity of 50 mPas at 25 ℃, and 10 parts by weight of an organopolysiloxane having a BET specific surface area of 200m2(g) fumed silica and 10 parts by weight of the microcapsule catalyst obtained in example 3 were mixed to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.3:1, and the content of the metal platinum is 498ppm of the silicone rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 12:
100 parts by weight of vinyl-containing polysiloxane with the viscosity of 980 Pa.s at 25 ℃, 30 parts by weight of organohydrogenpolysiloxane with the viscosity of 10000 mPa.s at 25 ℃ and 40 parts by weight of BET specific surface areaIs 100m2(iv)/g fumed silica and 3 parts by weight of the microcapsule catalyst obtained in example 4 to obtain a silicone rubber composition. Wherein, the molar ratio of the silicon-hydrogen bond in the organic hydrogen polysiloxane to the vinyl group in the vinyl-containing polysiloxane is 2:1, and the content of the metal platinum is 14ppm of the silicon rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 13:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 1000 pas at 25 ℃, 10 parts by weight of an organohydrogenpolysiloxane having a viscosity of 480 mPas at 25 ℃, and 20 parts by weight of an organopolysiloxane having a BET specific surface area of 200m2(g) fumed silica and 3 parts by weight of the microcapsule catalyst obtained in example 5 to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.2:1, and the content of the metal platinum is 15ppm of the silicone rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 14:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 100 pas at 25 ℃, 10 parts by weight of an organohydrogenpolysiloxane having a viscosity of 600 mPas at 25 ℃, and 20 parts by weight of an organopolysiloxane having a BET specific surface area of 200m2(iv)/g fumed silica and 3 parts by weight of the microcapsule catalyst obtained in example 6 to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.3:1, and the content of the metal platinum is 21ppm of the silicone rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 15:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 320 Pa.s at 25 ℃, 10 parts by weight of an organohydrogenpolysiloxane having a viscosity of 480 mPas at 25 ℃ and 3 parts by weight of the microcapsule catalyst obtained in example 7 were mixed to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.3:1, and the content of the metal platinum is 48ppm of the silicone rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 16:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 0.1 pas at 25 ℃, 10 parts by weight of an organohydrogenpolysiloxane having a viscosity of 100 mPas at 25 ℃ and 3 parts by weight of the microcapsule catalyst obtained in example 7 were mixed to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.25:1, and the content of the metal platinum is 48ppm of the silicone rubber composition. The cured product was heated and tested for viscosity change, and the test results are shown in Table 2.
Example 17:
100 parts by weight of a vinyl-containing polysiloxane having a viscosity of 60 pas at 25 ℃, 10 parts by weight of an organohydrogenpolysiloxane having a viscosity of 50 mPas at 25 ℃, and 20 parts by weight of an organohydrogenpolysiloxane having a BET specific surface area of 200m2(g) fumed silica and 2 parts by weight of the microcapsule catalyst obtained in example 8 to obtain a silicone rubber composition. Wherein the molar ratio of the silicon-hydrogen bond in the organohydrogenpolysiloxane to the vinyl group in the vinyl-containing polysiloxane is 1.3:1, and the content of the metal platinum is 20ppm of the silicone rubber composition. The curing time was measured by heat curing, and the test results are shown in Table 2.
TABLE 2
As can be seen from Table 2, the liquid silicone rubber has a small change in viscosity at room temperature and a long shelf life, and can be stored for 30 days without curing. In addition, the curing speed in example 17 was slower than that in examples 9 to 16, which shows that the expanded beads can promote the diffusion of the catalyst and increase the curing speed.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (14)
1. A silicone rubber composition comprising a base rubber and a microencapsulated catalyst;
wherein the microcapsule catalyst comprises a heated and melted organic silicon wax matrix and a hydrosilylation catalyst embedded in the organic silicon wax matrix.
2. The silicone rubber composition of claim 1, wherein the silicone wax matrix has a melting point of 50 ℃ to 80 ℃.
3. The silicone rubber composition of claim 1, wherein the microencapsulated catalyst further comprises expanded microspheres embedded in the silicone wax matrix.
4. The silicone rubber composition of claim 3, wherein the weight of the expanded microspheres is 0.1% to 3% of the weight of the silicone wax matrix.
5. The silicone rubber composition of claim 3, wherein the expanded microspheres have an initial thermal expansion temperature of less than 100 ℃.
6. The silicone rubber composition according to claim 1, wherein the hydrosilylation catalyst contains a metal, and the content of the metal in the microcapsule catalyst is 10ppm to 5000 ppm.
7. The silicone rubber composition according to claim 1, wherein the hydrosilylation catalyst comprises at least one of a platinum-based catalyst, a palladium-based catalyst, a rhodium-based catalyst, a ruthenium-based catalyst, a zirconium-based catalyst, a cobalt-based catalyst, and a nickel-based catalyst.
8. The silicone rubber composition according to claim 1, wherein the base rubber comprises a raw rubber and a crosslinking agent, the crosslinking agent is used in an amount of 10 to 30 parts by weight based on 100 parts by weight of the raw rubber, the microcapsule catalyst is used in an amount of 10 parts by weight based on the metal, and the metal is used in an amount of 10 parts by weight based on the metal-4Parts by weight-5X 10-2And (4) parts by weight.
9. The silicone rubber composition according to claim 8, wherein the raw rubber comprises a vinyl-containing polysiloxane, the crosslinking agent comprises an organohydrogenpolysiloxane, and the molar ratio of silicon-hydrogen bonds in the organohydrogenpolysiloxane to vinyl groups in the vinyl-containing polysiloxane is (1-2): 1.
10. The silicone rubber composition according to claim 9, wherein the vinyl-containing polysiloxane has a viscosity of 0.1 Pa-s to 1000 Pa-s at 25 ℃; and/or
The viscosity of the organohydrogenpolysiloxane at 25 ℃ is 0.5 mPas to 10000 mPas.
11. The preparation method of the silicone rubber is characterized by comprising the following steps:
providing a silicone rubber composition according to any one of claims 1 to 10;
and heating the silicon rubber composition to obtain the silicon rubber.
12. The method of preparing silicone rubber according to claim 11, wherein the maximum temperature of the heating is 50 ℃ to 200 ℃ and is higher than the melting point of the silicone wax matrix.
13. The method of producing silicone rubber according to claim 12, wherein the maximum temperature of the heating is higher than the initial thermal expansion temperature of the expanded microspheres.
14. A silicone rubber obtained by the production method according to any one of claims 11 to 13, wherein the silicone rubber has a network structure.
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| CN113736260A (en) * | 2021-08-16 | 2021-12-03 | 歌尔股份有限公司 | Vibrating diaphragm for sound production device and sound production device |
| CN114931944A (en) * | 2022-04-08 | 2022-08-23 | 广东天跃新材料股份有限公司 | Single-component platinum catalyst and application thereof in preparation of silicone rubber synthetic leather |
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