CN112724921A - Low-viscosity heat-conducting flame-retardant silicone rubber sealant and preparation method thereof - Google Patents
Low-viscosity heat-conducting flame-retardant silicone rubber sealant and preparation method thereof Download PDFInfo
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Abstract
The invention provides a low-viscosity heat-conducting flame-retardant silicone rubber sealant which is prepared from the following raw materials: 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane; 0.1-30 parts by weight of simethicone; 30-100 parts by weight of aluminum hydroxide; 0-50 parts by weight of heavy calcium carbonate; 0-50 parts by weight of alumina; 0-10 parts of color paste; 5-12 parts by weight of an organosilicon crosslinking agent; 0.01-5 parts by weight of a silane coupling agent; 0.05-8 parts by weight of a titanium-containing catalyst; 0-1 part by weight of platinum catalyst. Compared with the prior art, the low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention adopts specific content components, realizes better overall interaction, and has the advantages of environmental protection, low viscosity, good flame retardance, good heat-conducting capability and good adhesion. Experimental results show that the low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention has the surface drying time of 13-15 min, the viscosity of 18790-25360 mPa.s, the tensile strength of 1.82-2.23 MPa, the elongation at break of 105-158%, the heat conductivity coefficient of 0.50W/(m.K) -0.65W/(m.K), the flame-retardant grade of V-0UL94 and the PC shear strength of 1.23-1.35 MPa.
Description
Technical Field
The invention relates to the technical field of sealing, in particular to a low-viscosity heat-conducting flame-retardant silicone rubber sealant and a preparation method thereof.
Background
The silicone rubber sealant is a liquid vulcanized sealing material which takes silicone rubber as a main material and is matched with compounding agents such as a vulcanizing agent, a reinforcing agent and the like; the main structure of the composite material is mainly composed of silicon and oxygen atoms which are arranged alternately, two organic groups are usually connected to the silicon atoms, and the characteristics of the main chain determine that the composite material has excellent performances, such as excellent thermal stability, weather resistance, corrosion resistance, electrical insulation performance, air permeability and the like; therefore, silicone rubber products have been widely used in various fields such as buildings, industry, automobiles, new energy, electronic and electric appliances, and the like.
The single-component sealant in the prior art generally takes a calcium carbonate system as a main component and mainly serves for bonding and sealing, and the heat-conducting flame-retardant organic silicon pouring sealant used as the pouring sealant is a double-component product and generally has poor bonding property. At present, the heat conductivity and the flame retardance of organic silica gel in the electronic field have certain requirements, a product is required to have certain heat conductivity, good flame retardance and certain fluidity and adhesiveness, and the silica gel can be filled into gaps. The heat conductivity coefficient of the organic silica gel of the common calcium carbonate system is only 0.3W/(m.K), the heat dissipation requirement of components cannot be met, and the flame retardant grade is lower and only HB grade exists.
Disclosure of Invention
In view of the above, the invention aims to provide a low-viscosity heat-conducting flame-retardant silicone rubber sealant and a preparation method thereof.
The invention provides a low-viscosity heat-conducting flame-retardant silicone rubber sealant which is prepared from the following raw materials:
100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane;
0.1-30 parts by weight of simethicone;
30-100 parts by weight of aluminum hydroxide;
0-50 parts by weight of heavy calcium carbonate;
0-50 parts by weight of alumina;
0-10 parts of color paste;
5-12 parts by weight of an organosilicon crosslinking agent;
0.01-5 parts by weight of a silane coupling agent;
0.05-8 parts by weight of a titanium-containing catalyst;
0-1 part by weight of platinum catalyst.
Preferably, the kinematic viscosity of the alpha, omega-dihydroxy polydimethylsiloxane is 1000-50000 mm2/s。
Preferably, the kinematic viscosity of the dimethyl silicone oil is 50-5000 mm2/s。
Preferably, the organosilicon crosslinking agent is selected from one or more of methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, methyl orthosilicate and ethyl orthosilicate.
Preferably, the silane coupling agent is selected from one or more of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, gamma-aminoethylaminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane and epoxy oligomeric silane.
Preferably, the titanium-containing catalyst is selected from one or more of n-butyl titanate, isopropyl titanate, tert-butyl titanate and titanium ethyl acetoacetate complex.
The invention also provides a preparation method of the low-viscosity heat-conducting flame-retardant silicone rubber sealant, which comprises the following steps:
a) mixing and dehydrating alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, aluminum oxide and color paste, and cooling to obtain a base material;
b) adding an organic silicon cross-linking agent and a titanium-containing catalyst into the base material obtained in the step a) for primary vacuum stirring, and adding a silane coupling agent and a platinum catalyst for secondary vacuum stirring to obtain the low-viscosity heat-conducting flame-retardant silicone rubber sealant.
Preferably, the mixing and dewatering process in step a) specifically comprises:
alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, alumina and color paste are stirred at the rotating speed of 200r/min to 500r/min, and are simultaneously heated to 100 ℃ to 150 ℃ and dehydrated for 2h to 4h under the vacuum pressure of-0.09 MPa to-0.1 MPa.
Preferably, the temperature of said cooling in step a) is ≦ 50 ℃.
Preferably, the rotating speed of the first vacuum stirring in the step b) is 200 r/min-500 r/min, the pressure is-0.09 MPa-0.1 MPa, and the time is 10 min-60 min;
the rotation speed of the second vacuum stirring is 200 r/min-500 r/min, the pressure is-0.09 MPa-0.1 MPa, and the time is 10 min-60 min.
The invention provides a low-viscosity heat-conducting flame-retardant silicone rubber sealant which is prepared from the following raw materials: 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane; 0.1-30 parts by weight of simethicone; 30-100 parts by weight of aluminum hydroxide; 0-50 parts by weight of heavy calcium carbonate; 0-50 parts by weight of alumina; 0-10 parts of color paste; 5-12 parts by weight of an organosilicon crosslinking agent; 0.01-5 parts by weight of a silane coupling agent; 0.05-8 parts by weight of a titanium-containing catalyst; 0-1 part by weight of platinum catalyst. Compared with the prior art, the low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention adopts specific content components, realizes better overall interaction, and has the advantages of environmental protection, low viscosity, good flame retardance, good heat-conducting capability and good adhesion. Experimental results show that the low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention has the surface drying time of 13-15 min, the viscosity of 18790-25360 mPa.s, the tensile strength of 1.82-2.23 MPa, the elongation at break of 105-158%, the heat conductivity coefficient of 0.50W/(m.K) -0.65W/(m.K), the flame-retardant grade of V-0UL94 and the PC shear strength of 1.23-1.35 MPa.
In addition, the preparation method provided by the invention has the advantages of simple process, easily-controlled conditions and wide application prospect.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a low-viscosity heat-conducting flame-retardant silicone rubber sealant which is prepared from the following raw materials:
100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane;
0.1-30 parts by weight of simethicone;
30-100 parts by weight of aluminum hydroxide;
0-50 parts by weight of heavy calcium carbonate;
0-50 parts by weight of alumina;
0-10 parts of color paste;
5-12 parts by weight of an organosilicon crosslinking agent;
0.01-5 parts by weight of a silane coupling agent;
0.05-8 parts by weight of a titanium-containing catalyst;
0-1 part by weight of platinum catalyst.
In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, ground calcium carbonate, alumina, color paste, an organosilicon crosslinking agent, a silane coupling agent, a titanium-containing catalyst and a platinum catalyst, and preferably consists of alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, ground calcium carbonate, alumina, color paste, an organosilicon crosslinking agent, a silane coupling agent, a titanium-containing catalyst and a platinum catalyst.
In the present invention, the α, ω -dihydroxy polydimethylsiloxane is a base gum; the preferable kinematic viscosity of the alpha, omega-dihydroxy polydimethylsiloxane is 1000-50000 mm2More preferably 5000 to 20000 mm/s2And s. In a preferred embodiment of the invention, the alpha, omega-dihydroxy polydimethylsiloxane is 5000mm in kinematic viscosity2α, ω -dihydroxypolydimethylsiloxane,/s; in another preferred embodiment of the present invention, the α, ω -dihydroxypolydimethylsiloxane is a kinematic viscosity of 20000mm2S and 5000mm2Alpha, omega-dihydroxy polydimethylsiloxane/s, wherein the mass ratio of the two is 20000mm2α, ω -dihydroxypolydimethylsiloxane,/s: 5000mm2α, ω -dihydroxy polydimethylsiloxane,/s 20: 80. the source of the α, ω -dihydroxypolydimethylsiloxane is not particularly limited in the present invention, and commercially available products well known to those skilled in the art may be used. In the present invention, the low-viscosity thermally conductive flame retardant silicone rubber sealant includes 100 parts by weight of α, ω -dihydroxy polydimethylsiloxane.
In the present invention, the dimethylsilicone oil mainly functions as a plasticizer; the kinematic viscosity of the dimethyl silicone oil is preferably 50-5000 mm2S, more preferably 350mm2And s. The source of the dimethylsilicone fluid is not particularly limited in the present invention, and commercially available products known to those skilled in the art may be used. In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0.1-30 parts by weight of dimethyl silicone oil, and preferably 1-20 parts by weight.
The sources of the aluminum hydroxide, the ground calcium carbonate, the alumina and the color paste are not particularly limited in the present invention, and commercially available products well known to those skilled in the art can be used. In the present invention, the aluminum hydroxide, the ground calcium carbonate and the aluminum oxide are all aluminum hydroxide, ground calcium carbonate and aluminum oxide which are well known to those skilled in the art and are surface-treated by fatty acid, or aluminum hydroxide, ground calcium carbonate and aluminum oxide which are not surface-treated by fatty acid, and preferably the aluminum hydroxide, the ground calcium carbonate and the aluminum oxide which are surface-treated by fatty acid are easily dispersed into the rubber of the sealant to provide flame retardant and heat conducting capabilities. In the present invention, the particle size of the aluminum hydroxide, the ground calcium carbonate and the alumina is preferably 1 to 50 μm. In the invention, the color paste mainly plays a role of color mixing, and can be black color paste, white color paste or silver color paste which are well known by the technical personnel in the field; the color of the color paste can be selected by the person skilled in the art according to the actual use requirement.
In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 30-100 parts by weight of aluminum hydroxide, preferably 60-80 parts by weight; the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0-50 parts by weight of heavy calcium carbonate, preferably 50 parts by weight; the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0-50 parts by weight of alumina, preferably 20 parts by weight; the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0-10 parts by weight of color paste, preferably 6 parts by weight.
In the present invention, the organosilicon cross-linking agent mainly plays a role in cross-linking and curing, and reacts with alpha, omega-dihydroxy polydimethylsiloxane to make the sealant become an elastomer. In the present invention, the organosilicon crosslinking agent is preferably selected from one or more of methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, methyl orthosilicate, and ethyl orthosilicate, and more preferably methyltrimethoxysilane and/or vinyltrimethoxysilane. The source of the organosilicon crosslinking agent is not particularly limited in the present invention, and commercially available products of the above-mentioned methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, methyl orthosilicate, and ethyl orthosilicate, which are well known to those skilled in the art, may be used. In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 5-12 parts by weight of an organosilicon crosslinking agent, and preferably 8 parts by weight.
In the present invention, the silane coupling agent mainly plays a role of adhesion promotion. In the present invention, the silane coupling agent is preferably selected from one or more of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, gamma-aminoethylaminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane and epoxy-oligomeric silane, and more preferably gamma-aminoethylaminopropyltrimethoxysilane and/or epoxy-oligomeric silane. The source of the silane coupling agent is not particularly limited in the present invention, and commercially available products of the above aminopropyltrimethoxysilane, aminopropyltriethoxysilane, gamma-aminoethylaminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-glycidyloxypropyltrimethoxysilane and epoxy-oligomeric silane known to those skilled in the art can be used. In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0.01-5 parts by weight of silane coupling agent, preferably 1-2 parts by weight.
In the present invention, the titanium-containing catalyst mainly plays a role of accelerating the solidification. In the present invention, the titanium-containing catalyst is preferably selected from one or more of n-butyl titanate, isopropyl titanate, t-butyl titanate and titanium ethyl acetoacetate complex, more preferably titanium ethyl acetoacetate complex. The source of the titanium-containing catalyst in the present invention is not particularly limited, and commercially available products of the above-mentioned n-butyl titanate, isopropyl titanate, t-butyl titanate and titanium ethyl acetoacetate complex known to those skilled in the art may be used. In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0.05-8 parts by weight of titanium-containing catalyst, and preferably 4 parts by weight.
In the present invention, the platinum catalyst mainly plays a role in improving flame retardancy; preferably a commercially available platinum complex of diethylenetetramethyldisiloxane well known to those skilled in the art; the present invention is not particularly limited in this regard. In the invention, the low-viscosity heat-conducting flame-retardant silicone rubber sealant comprises 0-1 part by weight of platinum catalyst, preferably 0.2 part by weight.
The low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention adopts aluminum hydroxide, ground limestone and aluminum oxide as fillers, so that the flame-retardant capability and the heat-conducting capability of the sealant are provided; the titanium complex is used as a catalyst, so that the environmental protection performance of the sealant is provided (the organic silicon cross-linking agent and the titanium catalyst are environment-friendly due to alcohol substances generated in the curing process); and by reasonably controlling the components in the sealant and adjusting the content of each component, under the comprehensive action of each component, the sealant has the advantages of environmental protection, low viscosity, good flame retardance, good heat conductivity and good adhesiveness (the adhesive base material is aluminum, PC and the like).
The invention also provides a preparation method of the low-viscosity heat-conducting flame-retardant silicone rubber sealant, which comprises the following steps:
a) mixing and dehydrating alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, aluminum oxide and color paste, and cooling to obtain a base material;
b) adding an organic silicon cross-linking agent and a titanium-containing catalyst into the base material obtained in the step a) for primary vacuum stirring, and adding a silane coupling agent and a platinum catalyst for secondary vacuum stirring to obtain the low-viscosity heat-conducting flame-retardant silicone rubber sealant.
The invention firstly mixes and dehydrates alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, alumina and color paste, and cools to obtain the base material. In the invention, the alpha, omega-dihydroxy polydimethylsiloxane, the dimethyl silicone oil, the aluminum hydroxide, the heavy calcium carbonate, the alumina and the color paste are the same as those in the technical scheme, and are not described again.
The apparatus for mixing and dewatering is not particularly limited in the present invention, and a high-speed dispersion planetary machine well known to those skilled in the art is used.
In the present invention, the mixing and dewatering process is preferably specifically:
stirring alpha, omega-dihydroxy polydimethylsiloxane, simethicone, aluminum hydroxide, heavy calcium carbonate, alumina and color paste at the rotating speed of 200 r/min-500 r/min, simultaneously heating to 100-150 ℃, and dehydrating in vacuum for 2-4 h under-0.09-0.1 MPa;
more preferably:
alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, alumina and color paste are stirred at the rotating speed of 300r/min, and are heated to 110-130 ℃ simultaneously, and are dehydrated for 3 hours in vacuum under the pressure of-0.09 to-0.1 MPa.
In the present invention, the temperature of the cooling is preferably 50 ℃ or less.
After the base material is obtained, the organosilicon crosslinking agent and the titanium-containing catalyst are added into the obtained base material for primary vacuum stirring, and then the silane coupling agent and the platinum catalyst are added for secondary vacuum stirring, so that the low-viscosity heat-conducting flame-retardant silicone rubber sealant is obtained. In the present invention, the organosilicon crosslinking agent, the titanium-containing catalyst, the silane coupling agent and the platinum catalyst are the same as those in the above technical solution, and are not described herein again. The device for the first vacuum stirring and the second vacuum stirring is not particularly limited, and a planetary stirrer well known to those skilled in the art can be used.
In the invention, the rotation speed of the first vacuum stirring is preferably 200 r/min-500 r/min, and more preferably 300 r/min; the pressure of the first vacuum stirring is preferably-0.09 MPa to-0.1 MPa; the time of the first vacuum stirring is preferably 10min to 60min, and more preferably 40 min; on the basis, the materials are uniformly mixed.
In the invention, the rotation speed of the second vacuum stirring is preferably 200 r/min-500 r/min, and more preferably 300 r/min; the pressure of the second vacuum stirring is preferably-0.09 MPa to-0.1 MPa; the time of the second vacuum stirring is preferably 10min to 60min, and more preferably 40 min; on the basis, the materials are uniformly mixed.
The preparation method provided by the invention has the advantages of simple process, easily-controlled conditions and wide application prospect.
The invention provides a low-viscosity heat-conducting flame-retardant silicone rubber sealant which is prepared from the following raw materials: 100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane; 0.1-30 parts by weight of simethicone; 30-100 parts by weight of aluminum hydroxide; 0-50 parts by weight of heavy calcium carbonate; 0-50 parts by weight of alumina; 0-10 parts of color paste; 5-12 parts by weight of an organosilicon crosslinking agent; 0.01-5 parts by weight of a silane coupling agent; 0.05-8 parts by weight of a titanium-containing catalyst; 0-1 part by weight of platinum catalyst. Compared with the prior art, the low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention adopts specific content components, realizes better overall interaction, and has the advantages of environmental protection, low viscosity, good flame retardance, good heat-conducting capability and good adhesion. Experimental results show that the low-viscosity heat-conducting flame-retardant silicone rubber sealant provided by the invention has the surface drying time of 13-15 min, the viscosity of 18790-25360 mPa.s, the tensile strength of 1.82-2.23 MPa, the elongation at break of 105-158%, the heat conductivity coefficient of 0.50W/(m.K) -0.65W/(m.K), the flame-retardant grade of V-0UL94 and the PC shear strength of 1.23-1.35 MPa.
In addition, the preparation method provided by the invention has the advantages of simple process, easily-controlled conditions and wide application prospect.
To further illustrate the present invention, the following examples are provided for illustration. The aluminum hydroxide, heavy calcium carbonate and aluminum oxide used in the following examples of the present invention are aluminum hydroxide, heavy calcium carbonate and aluminum oxide surface-treated with fatty acid, and have a particle size of 1 to 50 μm.
Example 1
(1) The kinematic viscosity is 5000mm2Alpha, omega-dihydroxypolydimethylsiloxane,/s, 350mm2Putting dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, aluminum oxide and white slurry into a high-speed dispersion planetary machine for stirring (300r/min), simultaneously heating to 120 ℃, carrying out vacuum dehydration for 3h under-0.09 to-0.1 MPa, and cooling to below 50 ℃ after moisture removal to obtain a base material;
(2) adding methyltrimethoxysilane and the titanium ethyl acetoacetate compound into the base material obtained in the step (1), stirring (300r/min) uniformly (40min) under the vacuum (-0.09MPa to-0.1 MPa), adding gamma-aminoethyl aminopropyltrimethoxysilane, stirring (300r/min) uniformly (40min) under the vacuum (-0.09MPa to-0.1 MPa), and discharging to obtain the silicone rubber sealant.
The amounts and sources of the above raw materials are shown in table 1.
Table 1 amount and source of raw materials used in example 1 of the present invention
Example 2
(1) The kinematic viscosity is 20000mm2Alpha, omega-dihydroxypolydimethylsiloxane,/s, 5000mm2Alpha, omega-dihydroxypolydimethylsiloxane,/s, 350mm2Putting dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, aluminum oxide and white slurry into a high-speed dispersion planetary machine for stirring (300r/min), simultaneously heating to 120 ℃, carrying out vacuum dehydration for 3h under-0.09 to-0.1 MPa, and cooling to below 50 ℃ after moisture removal to obtain a base material;
(2) adding methyltrimethoxysilane, vinyl trimethoxysilane and an ethyl acetoacetate titanium compound into the base material obtained in the step (1), stirring (300r/min) uniformly (40min) under the vacuum (-0.09MPa to-0.1 MPa), adding epoxy oligomeric silane and a platinum catalyst, stirring (300r/min) uniformly (40min) under the vacuum (-0.09MPa to-0.1 MPa), and discharging to obtain the silicone rubber sealant.
The amounts and sources of the above raw materials are shown in table 2.
Table 2 amount and source of raw materials used in example 2 of the present invention
Comparative example 1
(1) The kinematic viscosity is 5000mm2Alpha, omega-dihydroxypolydimethylsiloxane,/s, 350mm2Putting the dimethyl silicone oil, the nano calcium carbonate and the white slurry into a high-speed dispersion planetary machine, stirring (300r/min), simultaneously heating to 120 ℃, carrying out vacuum dehydration for 3h under-0.09 to-0.1 MPa, and cooling to below 50 ℃ after moisture removal to obtain a base material;
(2) adding methyltrimethoxysilane and the titanium ethyl acetoacetate compound into the base material obtained in the step (1), stirring (300r/min) uniformly (40min) under the vacuum (-0.09MPa to-0.1 MPa), adding gamma-aminoethyl aminopropyltrimethoxysilane, stirring (300r/min) uniformly (40min) under the vacuum (-0.09MPa to-0.1 MPa), and discharging to obtain the silicone rubber sealant.
The amounts and sources of the above raw materials are shown in table 3.
Table 3 amounts and sources of raw materials used in comparative example 1
Examples of the experiments
According to the standard of HGT 5379-.
TABLE 4 test results of the properties of sealants prepared in examples of the present invention and comparative examples
| Item | Example 1 | Example 2 | Comparative example 1 |
| Surface drying time/min | 13 | 15 | 13 |
| viscosity/mPa.s | 25360 | 18790 | 67847 |
| Tensile strength/MPa | 2.23 | 1.82 | 2.31 |
| Elongation at break/% | 105 | 158 | 253 |
| Thermal conductivity/W/(m.K) | 0.65 | 0.50 | 0.36 |
| Flame retardant rating/UL 94 | V-0 | V-0 | HB |
| PC shear strength/MPa | 1.35 | 1.23 | 1.53 |
According to the embodiment, the aluminum hydroxide, the heavy calcium carbonate and the aluminum oxide are used as the filler, so that the flame retardant capability and the heat conduction capability of the sealant are improved; a titanium catalyst and silane coupling agent compound system is adopted, so that good adhesion can be ensured; the product is mainly used in the electronic industry, so that PC is used as a bonding material to test the shear strength, and the shear strength data obtained by testing in experimental examples can show that the sealant obtained by the invention has better bonding property to the PC material.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A low-viscosity heat-conducting flame-retardant silicone rubber sealant is prepared from the following raw materials:
100 parts by weight of alpha, omega-dihydroxy polydimethylsiloxane;
0.1-30 parts by weight of simethicone;
30-100 parts by weight of aluminum hydroxide;
0-50 parts by weight of heavy calcium carbonate;
0-50 parts by weight of alumina;
0-10 parts of color paste;
5-12 parts by weight of an organosilicon crosslinking agent;
0.01-5 parts by weight of a silane coupling agent;
0.05-8 parts by weight of a titanium-containing catalyst;
0-1 part by weight of platinum catalyst.
2. The low-viscosity heat-conducting flame-retardant silicone rubber sealant as claimed in claim 1, wherein the kinematic viscosity of the α, ω -dihydroxy polydimethylsiloxane is 1000 to 50000mm2/s。
3. The low-viscosity heat-conducting flame-retardant silicone rubber sealant as claimed in claim 1, wherein the kinematic viscosity of the dimethicone is 50-5000 mm2/s。
4. The low viscosity thermally conductive flame retardant silicone rubber sealant according to claim 1, wherein the silicone cross-linking agent is selected from one or more of methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, methyl orthosilicate, and ethyl orthosilicate.
5. The low viscosity thermally conductive flame retardant silicone rubber sealant according to claim 1, wherein the silane coupling agent is selected from one or more of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, gamma-aminoethylaminopropyltrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, and epoxy-oligomeric silane.
6. The low viscosity thermally conductive flame retardant silicone rubber sealant according to claim 1, wherein the titanium-containing catalyst is selected from one or more of n-butyl titanate, isopropyl titanate, t-butyl titanate, and titanium ethyl acetoacetate complex.
7. A method for preparing the low-viscosity heat-conducting flame-retardant silicone rubber sealant as claimed in any one of claims 1 to 6, comprising the following steps:
a) mixing and dehydrating alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, aluminum oxide and color paste, and cooling to obtain a base material;
b) adding an organic silicon cross-linking agent and a titanium-containing catalyst into the base material obtained in the step a) for primary vacuum stirring, and adding a silane coupling agent and a platinum catalyst for secondary vacuum stirring to obtain the low-viscosity heat-conducting flame-retardant silicone rubber sealant.
8. The preparation method according to claim 7, wherein the mixing and dewatering process in step a) is specifically as follows:
alpha, omega-dihydroxy polydimethylsiloxane, dimethyl silicone oil, aluminum hydroxide, heavy calcium carbonate, alumina and color paste are stirred at the rotating speed of 200r/min to 500r/min, and are simultaneously heated to 100 ℃ to 150 ℃ and dehydrated for 2h to 4h under the vacuum pressure of-0.09 MPa to-0.1 MPa.
9. The method of claim 7, wherein the temperature of the cooling in step a) is less than or equal to 50 ℃.
10. The preparation method according to claim 7, wherein the rotation speed of the first vacuum stirring in the step b) is 200r/min to 500r/min, the pressure is-0.09 MPa to-0.1 MPa, and the time is 10min to 60 min;
the rotation speed of the second vacuum stirring is 200 r/min-500 r/min, the pressure is-0.09 MPa-0.1 MPa, and the time is 10 min-60 min.
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