High-temperature-resistant silicone sealant and preparation method thereof

Abstract

The application discloses a high-temperature-resistant silicone sealant and a preparation method thereof. The sealant comprises A component and B component. The A component is prepared from 100 parts of alpha, omega-dihydroxypolydimethylsiloxane, 5-40 parts of a filler, 5-10 parts of a hydrogen adsorbent, 1-3 parts of carbon fiber, 5-10 parts of vinyl fluorosilicone oil and 0.5-1 part of a catalyst. The B component is prepared from 100 parts of hydrogen-containing polysilazane resin, 100-500 parts of a diluent, 10-50 parts of a water-removing agent and 20-100 parts of a filler. The sealant contains SiH-NH-SiH structure, can react with alpha, omega-dihydroxypolydimethylsiloxane to generate elastomers, can eliminate excessive water and catalyst in the system through hydrolysis, and can make the generated elastomers have excellent high-temperature resistance and humidity resistance. Meanwhile, the structure can react with hydroxyl groups on the surface of materials, so that the sealant has excellent bonding properties on glass, ceramic and metal materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sealing materials, and particularly relates to a high-temperature-resistant organic silicon sealant and a preparation method thereof. BACKGROUND

[0002] The organic silicon polymer is a molecule main chain of siloxysilicon, and the structure endows the material with excellent high and low temperature performance, and is widely applied in electronic, electrical, automobile, lighting and other industries, and is one of the sealants with the largest amount at present. The organic silicon polymer can be cured at room temperature, and the curing forms mainly include acid removal type, alcohol removal type, ketoxime removal type, acetone removal type, amine removal type and dehydrogenation type, and the condensation products mainly include small molecules of acid, alcohol, ketoxime and the like. The existence of residual condensation products, organotin catalyst and water makes the sealant prone to depolymerization reaction in a high-temperature environment, especially in a humid heat environment, thereby limiting the application of the sealant in the high-temperature and humid heat environment. Although the dehydrogenation type sealant has relatively good high-temperature resistance in the humid heat environment, the platinum catalyst is high in cost and easy to be poisoned and inactivated to cause the sealant not to be cured, and the organotin catalyst is low in high-temperature resistance. At the same time, the hydrogen generated in the curing process of the dehydrogenation type sealant is easy to form bubbles, thereby obviously reducing the mechanical properties of the sealant. In addition, it is difficult to additionally add a silane coupling agent in the two-component dehydrogenation type organic silicon sealant system, and the adhesion performance is relatively poor, and a matching adhesion treatment agent is required in use, thereby making the construction more complex. In the above system, since the main chain structure is siloxysilicon, the non-polar medium resistance is also relatively poor, and the system is difficult to be applied in the environment of contacting oil and the like non-polar medium.

[0003] Therefore, it is extremely necessary to develop an organic silicon sealant with high-temperature resistance, humid heat resistance and non-polar medium resistance. SUMMARY

[0004] The application aims to provide a high-temperature-resistant organic silicon sealant and a preparation method thereof.

[0005] The application provides a high-temperature-resistant organic silicon sealant, which comprises components A and B, and the mass ratio of the two components A and B is 100:(1-3); the weight parts of each component in the component A are as follows: alpha, omega-dihydroxy polydimethylsiloxane 100 parts, filler 5-40 parts, hydrogen adsorbent 5-10 parts, carbon fiber 1-3 parts, vinyl fluorosilicone oil 5-10 parts and catalyst 0.5-1 part.

[0006] The weight parts of each component in the component B are as follows: hydrogen-containing polysilazane resin 100 parts, diluent 100-500 parts, water removal agent 10-50 parts and filler 20-100 parts.

[0007] The viscosity of the α, ω-dihydroxyl polydimethylsiloxane is 40-120 Pa·s at 25℃. The higher the viscosity of the liquid silicone rubber, the higher the relative molecular mass, the relatively less amount of dehydrogenation crosslinking agent required, the lower the amount of hydrogen produced, the less foaming of the prepared sealant, and the relatively better mechanical properties of the prepared sealant.

[0008] The filler is one of fumed silica treated with D3F siloxane or precipitated silica or a mixture thereof. The preparation method of the fumed silica treated with D3F siloxane is as follows: the silica is placed in a stirred tank, 10% D3F siloxane liquid of the mass of the silica is sprayed into the tank by a watering can, and stirring treatment is carried out at a temperature of 100-120℃ for 4-5h. The fumed silica treated with D3F siloxane not only has good compatibility with the silicone rubber, but also has relatively better mechanical properties of the prepared sealant, and the introduction of fluorine atoms increases the polarity of the sealant and improves the non-polar medium resistance of the sealant.

[0009] The hydrogen adsorbent is platinum-loaded 5A molecular sieve.

[0010] The carbon fiber is a short carbon fiber, the aspect ratio of which is 15:1, and the diameter of which is 7-10μm.

[0011] The viscosity of the vinyl fluorosilicone oil is 0.05-0.5 Pa·s. The vinyl fluorosilicone oil has good compatibility with the silicone rubber, can effectively improve the viscosity of the sealant, and is convenient for construction. In addition, the vinyl fluorosilicone oil can react with the hydrogen-containing polysilazane resin, is a potential active diluent of the silicone sealant, and further improves the non-polar medium resistance of the sealant.

[0012] The catalyst is dibutyl tin diacetate.

[0013] The hydrogen-containing polysilazane resin is a mixture of the compounds of formula I and formula II according to a mass ratio of 1:1; the molecular weight of the compounds of formula I and formula II is 800-900; x in formula II is 8-12, and y is 2-6;

[0014]

[0015] The diluent is toluene; and the water removing agent is CH-6 environmentally friendly water removing agent.

[0016] The preparation method of the high-temperature-resistant silicone sealant is carried out according to the following steps:

[0017] Preparation of A component: the α, ω-dihydroxy polydimethylsiloxane, filler, carbon fiber are weighed according to the mass fraction ratio, put into a blender, stirred and vacuum mixed at 100℃, stirred at 300-800rpm for 60-90min, then when the temperature drops to below 60℃, vinyl fluorosilicone oil, catalyst and hydrogen adsorbent are added according to the mass fraction, vacuumed to a vacuum degree of not more than-0.08MPa for 5-10min, then start stirring, continue stirring at 300-800rpm for 60-90min to obtain A component;

[0018] Preparation of B component: the diluent, filler and water removal agent are weighed according to the mass fraction ratio, put into a blender, stirred and vacuum mixed, stirred at 300-800rpm for 30-60min, then the hydrogen-containing polysilazane resin is added according to the mass fraction ratio, then vacuum stirred at 300-800rpm for 30-60min to obtain B component.

[0019] The beneficial effects of the present application: the present application uses hydrogen-containing polysilazane resin to react with α, ω-dihydroxy polydimethylsiloxane to form an elastomer, the hydrogen-containing polysilazane resin contains SiH-NH-SiH structure, which can react with α, ω-dihydroxy polydimethylsiloxane to form an elastomer on one hand, and can itself hydrolyze and eliminate excess water and catalyst in the system, so that the generated elastomer has excellent high temperature resistance and moisture resistance, and at the same time, the structure can react with the hydroxyl group on the surface of the material, thereby having excellent bonding properties to glass, ceramic, metal and other materials without using silane coupling agent and other adhesion promoters. The platinum-loaded 5A molecular sieve is used as a hydrogen adsorbent, which can effectively adsorb hydrogen in the system, thereby improving the mechanical properties and high temperature resistance of the sealant. Short carbon fibers are used to improve the hardness of the silicone sealant. In addition, since the short carbon fibers have poor compatibility with the silicone glue, the hydrogen generated by the reaction of the system can overflow along the surface of the short carbon fibers, thereby effectively reducing the foaming problem of the sealant. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present application, the present application will be described more fully below. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0021] In the following examples, the hydrogen adsorbent used is platinum-loaded 5A molecular sieve, which is prepared by blending 5A molecular sieve with an aqueous solution of chloroplatinic acid at a volume ratio of 1:1, wherein the platinum content is 1% relative to the mass of 5A molecular sieve, and then drying at 100°C after mixing for 8h, and vacuum treatment at 350°C for at least 4h before use. The water removal agent is an environmentally friendly water removal agent produced by Caihe Industry Co., Ltd., model Caihe CH-6. The molecular weight of the compound of formula I is about 850, and the molecular weight of the compound of formula II is about 880; x is 10 and y is 4 in formula II; the compound of formula I is purchased from Anhui Aiyouta Silicone Co., Ltd., item number IOTA-PHPS; and the compound of formula II is purchased from Anhui Aiyouta Silicone Co., Ltd., item number IOTA-9150.

[0022] Example 1

[0023] The high-temperature-resistant silicone seal in this example is prepared according to the following mass parts:

[0024] Component A: α, ω-dihydroxy polydimethylsiloxane (viscosity 40 Pa·s) 100 parts, D3F siloxane-treated fumed silica 40 parts, hydrogen adsorbent 10 parts, carbon fiber (aspect ratio 15:1, diameter 8 μm) 1 part, vinyl fluorosilicone oil (viscosity 0.05 Pa·s) 10 parts, dibutyltin dilaurate 0.5 parts;

[0025] Component B: hydrogen-containing polysilazane resin (a mixture of compounds of formula I and formula II at a mass ratio of 1:1) 100 parts, diluent (toluene) 500 parts, CH-6 environmentally friendly water removal agent 50 parts, D3F siloxane-treated fumed silica 100 parts.

[0026] Preparation method of component A:

[0027] α, ω-dihydroxy polydimethylsiloxane, D3F siloxane-treated fumed silica, and carbon fiber are weighed according to the mass parts, placed in a blender, and mixed under vacuum at 100°C, stirred at a speed of 300 revolutions / min for 90 min, then vinyl fluorosilicone oil, dibutyltin dilaurate, and hydrogen adsorbent are added according to the mass parts when the temperature drops below 60°C, vacuumed to a vacuum degree of not more than -0.08 MPa, stirred at a speed of 300 revolutions / min for 90 min after maintaining for 5 min, and then component A is obtained.

[0028] Preparation method of component B:

[0029] The toluene, D3F siloxane treated fumed silica and CH-6 environmentally friendly water scavenger were weighed according to the mass fraction ratio, stirred and mixed under vacuum in a blender, stirred for 30 min at a speed of 800 r / min, then the hydrogen-containing polysilazane resin was added according to the mass fraction, and then stirred for 60 min under vacuum at a speed of 300 r / min to obtain the B component.

[0030] In use, the A component and the B component are mixed according to a mass ratio of 100:2.

[0031] Example 2

[0032] The high-temperature-resistant silicone sealant in this example was prepared according to the following mass fraction:

[0033] The A component: α, ω-dihydroxy polydimethylsiloxane 100 parts (viscosity 120 Pa·s), D3F siloxane treated precipitated silica 5 parts, hydrogen adsorbent 5 parts, carbon fiber (length-diameter ratio 15:1, diameter 9 μm) 3 parts, vinyl fluorosilicone oil (viscosity 0.05 Pa·s) 5 parts, dibutyl tin diacetate 1 part.

[0034] The B component: hydrogen-containing polysilazane resin (a mixture of compounds described in formula I and formula II according to a mass ratio of 1:1) 100 parts, diluent (toluene) 500 parts, CH-6 environmentally friendly water scavenger 50 parts, D3F siloxane treated precipitated silica 80 parts.

[0035] Preparation method of the A component:

[0036] The α, ω-dihydroxy polydimethylsiloxane, D3F siloxane treated precipitated silica and carbon fiber were weighed according to the mass fraction ratio, stirred and mixed under vacuum in a blender at 100℃, stirred for 60 min at a speed of 800 r / min, then the vinyl fluorosilicone oil, dibutyl tin diacetate and hydrogen adsorbent were added according to the mass fraction when the temperature was reduced to below 60℃, the vacuum degree was not greater than -0.08 MPa, stirring was started after 5 min, and then the A component was obtained by continuing to stir for 60 min at a speed of 800 r / min.

[0037] Preparation method of the B component:

[0038] The toluene, D3F siloxane treated precipitated silica and CH-6 environmentally friendly water scavenger were weighed according to the mass fraction ratio, stirred and mixed under vacuum in a blender, stirred for 60 min at a speed of 300 r / min, then the hydrogen-containing polysilazane resin was added according to the mass fraction, and then stirred for 60 min under vacuum at a speed of 300 r / min to obtain the B component.

[0039] In use, the A component and the B component are mixed according to a mass ratio of 100:1.

[0040] Example 3

[0041] The high-temperature-resistant silicone sealant in this example is prepared according to the following mass proportions:

[0042] A component: α, ω-dihydroxy polydimethylsiloxane 100 parts (viscosity 50 Pa s), D3F siloxane-treated precipitated silica 20 parts, hydrogen adsorbent 5 parts, carbon fiber (aspect ratio 15:1, diameter 10 μm) 2 parts, vinyl fluorosilicone oil (viscosity 0.5 Pa s) 8 parts, dibutyltin dilaurate 0.5 part.

[0043] B component: hydrogen-containing polysilazane resin (mixture of compounds described in Formula I and Formula II according to a mass ratio of 1:1) 50 parts, diluent (toluene) 100 parts, CH-6 environmentally friendly water removal agent 10 parts, D3F siloxane-treated precipitated silica 20 parts.

[0044] Preparation method of A component:

[0045] α, ω-dihydroxy polydimethylsiloxane, D3F siloxane-treated precipitated silica, and carbon fiber are weighed according to the mass fraction ratio, put into a blender, stirred, and vacuum-mixed at 100°C, stirred at a speed of 500 revolutions / min for 60 min, then vinyl fluorosilicone oil, dibutyltin dilaurate, and hydrogen adsorbent are added according to the mass fraction when the temperature drops below 60°C, vacuumed to a vacuum degree of not more than -0.08 MPa, stirred again after 5 min, and stirred at a speed of 500 revolutions / min for 60 min to obtain A component.

[0046] Preparation method of B component:

[0047] Toluene, D3F siloxane-treated precipitated silica, and CH-6 environmentally friendly water removal agent are weighed according to the mass fraction ratio, put into a blender, stirred, and vacuum-mixed, stirred at a speed of 300 revolutions / min for 60 min, then all-hydrogen and partial hydrogen-containing polysilazane resin is added, then vacuum-stirred at a speed of 300 revolutions / min for 60 min to obtain B component.

[0048] Example 4

[0049] The high-temperature-resistant silicone sealant in this example is prepared according to the following mass proportions:

[0050] A component: α, ω-dihydroxy polydimethylsiloxane 100 parts (viscosity 80 Pa s), D3F siloxane-treated fumed silica 20 parts, hydrogen adsorbent 8 parts, carbon fiber (aspect ratio 15:1, diameter 10 μm) 1 part, vinyl fluorosilicone oil (viscosity 0.2 Pa s) 8 parts, dibutyltin dilaurate 0.6 part.

[0051] B component: hydrogen-containing polysilazane resin (a mixture of compounds described in Formula I and Formula II according to a mass ratio of 1:1) 100 parts, diluent (toluene) 400 parts, CH-6 environmentally friendly water removal agent 40 parts, D3F siloxane treated precipitated silica 40 parts.

[0052] Preparation method of A component:

[0053] According to the mass fraction, α, ω-dihydroxy polydimethylsiloxane, D3F siloxane treated fumed silica, carbon fiber were weighed and put into a blender to stir and vacuum mix at 100℃, stirred at a speed of 500 revolutions / min for 60 min, then when the temperature dropped below 60℃, vinyl fluorosilicone oil, dibutyltin diacetate and hydrogen adsorbent were added according to the mass fraction, vacuumed to a vacuum degree of not more than-0.08MPa, kept for 5 min, then started to stir again, continued to stir at a speed of 500 revolutions / min for 60 min to obtain A component.

[0054] Preparation method of B component:

[0055] According to the mass fraction, toluene, D3F siloxane treated precipitated silica and CH-6 environmentally friendly water removal agent were put into a blender to stir and vacuum mix, stirred at a speed of 500 revolutions / min for 60 min, then hydrogen-containing polysilazane resin was added according to the mass fraction, then vacuum stirred at a speed of 500 revolutions / min for 60 min to obtain B component.

[0056] Comparative Example 1

[0057] The high-temperature-resistant silicone seal in this example was prepared according to the following mass fraction:

[0058] A component: α, ω-dihydroxy polydimethylsiloxane (viscosity 40Pa·s) 100 parts, fumed silica 40 parts, silicone oil (viscosity 0.5Pa·s) 10 parts, catalyst 0.5 parts.

[0059] B component: tetraethyl orthosilicate 100 parts, fumed silica 5 parts.

[0060] Preparation method of A component:

[0061] According to the mass fraction, α, ω-dihydroxy polydimethylsiloxane, filler were weighed and put into a blender to stir and vacuum mix at 100℃, stirred at a speed of 300 revolutions / min for 90 min, then when the temperature dropped below 60℃, silicone oil and catalyst were added according to the mass fraction, continued to stir at a speed of 300 revolutions / min for 90 min to obtain A component.

[0062] Preparation method of B component:

[0063] The tetraethyl orthosilicate and the silicon dioxide are weighed according to the mass ratio, stirred in a blender, and mixed under vacuum, and stirred at a speed of 500 revolutions per minute for 60 minutes.

[0064] When used, the A component and the B component are mixed according to a mass ratio of 100:2.

[0065] Comparative Example 2

[0066] The high-temperature-resistant silicone sealant in the present embodiment is prepared according to the following mass ratio:

[0067] The A component: α, ω-dihydroxy polydimethylsiloxane (viscosity 40 Pa·s) 100 parts, fumed silica 40 parts, silicone oil (viscosity 0.5 Pa·s) 10 parts, catalyst 0.5 parts;

[0068] The B component: methyl hydrogen-containing silicone oil (hydrogen content 1.4 wt%) 100 parts, fumed silica 10 parts.

[0069] Preparation method of the A component:

[0070] The α, ω-dihydroxy polydimethylsiloxane and the filler are weighed according to the mass ratio, stirred in a blender, mixed under vacuum at 100°C, stirred at a speed of 300 revolutions per minute for 90 minutes, then the silicone oil and the catalyst are added when the temperature is below 60°C according to the mass ratio, and the stirring is continued at a speed of 300 revolutions per minute for 90 minutes to obtain the A component.

[0071] Preparation method of the B component:

[0072] The methyl hydrogen-containing silicone oil 100 parts and the fumed silica 5 parts are weighed according to the mass ratio, stirred in a blender, and mixed under vacuum, and stirred at a speed of 500 revolutions per minute for 30 minutes to obtain the B component.

[0073] When used, the A component and the B component are mixed according to a mass ratio of 100:2.

[0074] The performance comparison of the above examples and comparative examples is shown in Table 1. Among them, the setting time is tested according to GB / T513477.5-2003, the tensile property is determined according to GB / T 528-2009, the density is determined according to GB / T 533-2008, the shear strength is determined according to GB / T 7124-2008, and the hardness is determined according to GB / T531-1999.

[0075] Table 1: Key performance data table of each example and comparative example of sealant

[0076]

[0077] As shown in Table 1, the hardness of Examples 1-4 is comparable to that of Comparative Examples 1-2, and the sealant has good adhesion to aluminum alloy, stainless steel, glass and other materials, while the adhesion of Comparative Examples 1-2 to stainless steel, titanium alloy and quartz glass is interface failure, and the adhesion is poor. The density of Examples 1-4 is comparable to that of Comparative Examples 1-2. After heat aging at 200℃ for 8h, the hardness of the sealant of Examples 1-4 slightly increases, and no degradation reaction occurs. As shown in the above data table, the sealant of the present application has not only good high-temperature resistance, but also good adhesion to various materials without using silane coupling agent and other adhesion promoters.

[0078] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as limiting the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the present application patent should be subject to the appended claims.

Claims

1. A high temperature resistant silicone sealant, characterized by, It comprises A component and B component, the mass ratio of the two components is 100:(1-3); the weight fraction of each component in A component is: alpha, omega-dihydroxy polydimethylsiloxane 100 parts, filler 5-40 parts, hydrogen adsorbent 5-10 parts, carbon fiber 1-3 parts, vinyl fluorosilicone oil 5-10 parts, catalyst 0.5-1 part; The weight fraction of each component in B component is: hydrogen-containing polysilazane resin 100 parts, diluent 100-500 parts, water removal agent 10-50 parts, filler 20-100 parts; The hydrogen-containing polysilazane resin is a mixture of compounds of formula I and formula II in a mass ratio of 1:1; the molecular weight of the compounds of formula I and formula II is 800-900; x in formula II is 8-12, and y is 2-6; 2. The high temperature resistant silicone sealant according to claim 1, wherein, The viscosity of the alpha, omega-dihydroxy polydimethylsiloxane is 40-120 Pa·s at 25°C.

3. The high temperature resistant silicone sealant of claim 1, wherein, The filler is one or a mixture of fumed silica or precipitated silica treated with D3F siloxane.

4. The high temperature resistant silicone sealant of claim 1, wherein, The hydrogen adsorbent is platinum-loaded 5A molecular sieve.

5. The high temperature resistant silicone sealant according to claim 1, wherein The carbon fiber is short carbon fiber with an aspect ratio of 15:1 and a diameter of 7-10 μm.

6. The high temperature resistant silicone sealant according to claim 1, wherein The viscosity of the vinyl fluorosilicone oil is 0.05-0.5 Pa·s.

7. The high temperature resistant silicone sealant according to claim 1, wherein The catalyst is dibutyl tin diacetate.

8. The high temperature resistant silicone sealant according to claim 1, wherein, The diluent is toluene; the water removal agent is CH-6 environmentally friendly water removal agent.

9. The method of making the high temperature resistant silicone sealant of claim 1, characterized in that, The following steps are followed: Preparation of A component: weigh alpha, omega-dihydroxy polydimethylsiloxane, filler, and carbon fiber according to the mass fraction ratio, put them into a blender, stir and vacuum mix at 100°C, stir at a speed of 300-800 rpm for 60-90 min, then add vinyl fluorosilicone oil, catalyst, and hydrogen adsorbent when the temperature drops below 60°C, vacuumize to a vacuum degree of not more than -0.08 MPa for 5-10 min, then start stirring again, continue stirring at a speed of 300-800 rpm for 60-90 min to obtain A component; Preparation of B component: weigh diluent, filler, and water removal agent according to the mass fraction ratio, put them into a blender, stir and vacuum mix, stir at a speed of 300-800 rpm for 30-60 min, then add hydrogen-containing polysilazane resin according to the mass fraction ratio, then vacuumize and stir at a speed of 300-800 rpm for 30-60 min to obtain B component.

Images