A high foaming ratio liquid silicone rubber foam material and its preparation method and application

Abstract

The present invention relates to the field of organic silicon technology, and specifically to a high foaming ratio liquid silicone rubber foam material, a preparation method thereof and an application thereof. The high foaming ratio liquid silicone rubber foam material is mainly made of the following raw material components in parts by weight: 100 parts of base rubber, 20 to 50 parts of vinyl silicone oil, 1 to 20 parts of hydrogen-containing silicone oil, 5 to 20 parts of reinforcing fillers, 60 to 120 parts of flame retardant fillers, 1 to 6 parts of foaming agents, 1 to 5 parts of non-ionic organic silicon surfactants, 0.5 to 5 parts of auxiliary foaming agents, 0.02 to 0.1 parts of inhibitors, 0.1 to 1 parts of catalysts, and 0 to 20 parts of pigments. The high foaming ratio liquid silicone rubber foam material prepared by the present invention has a high foaming ratio, fine pores, and uniform size, while meeting environmental protection and high flame retardant characteristics.

Description

Technical Field

[0001] The invention relates to the technical field of organic silicon, and in particular to a high-foaming ratio liquid silicone rubber foam material and a preparation method and application thereof. Background Art

[0002] Silicone rubber foam combines the heat resistance, cold resistance, and electrical insulation of silicone rubber with the elasticity of sponge. Therefore, it is used in the fields of construction, automobiles, etc. to promote the low thermal conductivity, noise reduction, and lightweight of materials.

[0003] The foaming agents of silicone rubber mainly include chemical foaming agents, physical foaming agents and surfactant foaming agents. Since physical foaming agents and surfactant foaming agents avoid the toxicity and pungent odor of chemical foaming agents and have unlimited scope of use, most of them prefer safe and environmentally friendly non-chemical foaming agents. Among this type of foaming process, the most researched are water-based system foaming process, compressed gas foaming process and surfactant foaming agent system.

[0004] For example, CN 108129692 A discloses a foaming silicone rubber material and a preparation method thereof. In the system, air, nitrogen, carbon dioxide, helium and other gases are injected. The reactor is subjected to additional pressure, and homogenization is required to form fine high-pressure foaming. This increases the requirements for equipment and requires strict pressure control. The pressure difference between the discharge pressure and the atmospheric pressure is large. Before vulcanization, it is easy to collapse after foaming, which is particularly unfavorable for the calendering molding operation of the atmospheric pressure process. The process is difficult to control and the pores are prone to unevenness. For the aqueous foaming system, the key lies in the source and use of water: water can be directly used as a foaming agent to form pores by evaporation of water; other gases such as H2 produced by the reaction of water and other substances in the system can also form pores; it can also be the system substances themselves that react to produce water and then use it as a foaming agent. The presence of water generally requires high-temperature vulcanization reaction or secondary vulcanization. Then the problem that follows is whether the vulcanization rate matches the foaming rate during high-temperature vulcanization; whether the secondary vulcanization affects the formed pores and causes the pores to collapse; whether the secondary vulcanization will decompose some substances in the foaming material and produce adverse substances. CN105602258 B discloses a low-density foamed silicone rubber composition and a silicone rubber sponge. A certain amount of low-melting-point solid non-ionic surfactant is added to the existing disclosed formula of a silicon-hydrogen foamed silicone rubber composition. The disclosed formula does not utilize foam materials of a specific shape and requires additional addition of a release agent, such as zinc stearate, which increases costs and the risk of producing harmful substances during secondary vulcanization.

[0005] Whether using non-ionic surfactants or biological surfactants for foaming, there is a problem of unstable storage of foamed materials after vulcanization below 120°C. When there is no release paper or film covering the surface of the material, especially when the materials are stacked or curled together, the materials will stick together after a long time and it is difficult to separate them. Secondary vulcanization at 180-200°C is required to stabilize them. On the one hand, it may be because most systems use acetylene alcohol inhibitors. Due to the coverage of the release film, this type of volatile inhibitor is easy to exert on the surface of the foam material during the primary vulcanization process, which is easy to cause incomplete surface reaction during the short process drying process. After leaving the covering film, the surfaces of the materials are easy to react again after contact, which makes them unstable and difficult to separate. On the other hand, the presence of water requires secondary vulcanization at a high temperature of 180-200°C to remove excess water vapor from the silicone rubber material to ensure dryness and the stability of the pores. Summary of the invention

[0006] In view of the problems and shortcomings in the prior art, the purpose of the present invention is to provide a liquid silicone rubber foam material with a high foaming ratio and a preparation method and application thereof.

[0007] To achieve the purpose of the invention, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides a high foaming ratio liquid silicone rubber foam material, which is mainly made of the following raw material components in parts by weight: 100 parts of base rubber, 20-50 parts of vinyl silicone oil, 1-20 parts of hydrogen-containing silicone oil, 5-20 parts of reinforcing filler, 60-120 parts of flame retardant filler, 1-6 parts of foaming agent, 1-5 parts of non-ionic silicone surfactant, 0.5-5 parts of auxiliary foaming agent, 0.02-0.1 parts of inhibitor, 0.1-1 parts of catalyst, and 0-20 parts of pigment; the HLB value of the non-ionic silicone surfactant is 1-10, and its structure is:

[0009]

[0010] Wherein R1 is a C6-18 alkane, a is an integer of 10-100, b is an integer of 1-8, c is an integer of 2-20; x is an integer of 2-20, y is an integer of 0-20; R2 is hydrogen, methyl or butyl.

[0011] The preparation steps of the nonionic silicone surfactant are:

[0012] (1) Add hydrogenated silicone oil and isopropanol solvent into the reactor, introduce cooling water, N2 protection, stir and heat to 80-110°C, add 2-10 ppm of chloroplatinic acid catalyst diluted with isopropanol, mix for 2-5 minutes, and maintain the temperature at 80-110°C;

[0013] (2) Add the mixture of C6-C18 olefin and allyl polyoxyethylene polyoxypropylene ether dropwise into the reactor, control the addition to be completed over 30-60 minutes, maintain reflux reaction at 90-110°C for several hours, until the system becomes translucent to transparent, and stop the reaction;

[0014] (3) Under a temperature condition of 90 to 110° C., isopropyl alcohol is distilled off under reduced pressure, and the remaining substance in the reaction container is collected to obtain a translucent to transparent liquid nonionic silicone surfactant.

[0015] Preferably, the HLB value of the nonionic silicone surfactant when added to the formula is preferably 3-6; when used, two or more types can be compounded and used, and the HLB value of the mixed nonionic silicone surfactant after compounding two or more types is preferably 3-6.

[0016] Preferably, the foaming agent is a non-ionic polymer compound powder with a water content of 80% to 99%.

[0017] More preferably, the non-ionic polymer compound is a polyvinyl pyrrolidone polymer compound with a molecular weight of 30,000 to 80,000.

[0018] Preferably, the base rubber is mainly kneaded from vinyl silicone oil, white carbon black and a structuring control agent.

[0019] More preferably, the base rubber is prepared by the following method: vinyl silicone oil, white carbon black, and a structuring control agent are weighed by weight, mixed in a kneader, heated and kneaded, then added into water for neutralization, and then small molecules in the base rubber are removed under vacuum conditions, cooled, sealed and stored for later use. Through the kneading process, a higher content of white carbon black can be evenly dispersed in the vinyl silicone oil to enhance the reinforcement effect, thereby making the liquid material more viscous.

[0020] More preferably, the kneading time is 2 to 4 hours; under vacuum conditions, the pressure is -0.09 to -0.1 MPa, the temperature is 130 to 150°C; and the cooling temperature is 20 to 40°C.

[0021] Preferably, the vinyl silicone oil structure is:

[0022] ,

[0023] or

[0024]

[0025] Wherein R1, R2, R3 are independently methyl, ethyl, and phenyl respectively; m is an integer from 10 to 10,000, x is an integer from 2 to 100, y is an integer from 10 to 10,000, and n is an integer from 2 to 100.

[0026] Preferably, the structure of the hydrogen-containing silicone oil is:

[0027] ,

[0028] or

[0029]

[0030] Wherein R4, R5, R6 are independently methyl, ethyl, phenyl; R4', R5' are independently C1-C18 straight chain or branched alkyl, C3-C20 cycloalkyl, C6-C20 aryl; a is an integer of 3-50, b is an integer of 0-1000, c is an integer of 1-50, d is an integer of 0-1000, and p is an integer of 2-100.

[0031] Preferably, the reinforcing filler is at least one of methyl MQ resin, vinyl MQ resin and methyl phenyl MQ resin.

[0032] Preferably, the flame retardant filler is halogen-free flame retardant powder.

[0033] More preferably, the halogen-free flame retardant powder is at least one of aluminum hydroxide, surface-modified aluminum hydroxide, and melamine cyanurate MCA.

[0034] Preferably, the auxiliary foaming agent is organic silanol.

[0035] More preferably, the organosilanol is at least one of trimethylsilanol, triethylsilanol, diethyldisilanol, dimethylphenylsilanol and triphenylsilanol.

[0036] Preferably, the inhibitor is at least one of acetylenic alcohol compounds, polyvinyl compounds, maleate compounds, and triphenylphosphine oxide.

[0037] More preferably, the inhibitor is at least one of 3-methyl-1-butyn-3-ol, trimethyl-1-pentyn-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynyl-1-cyclohexanol, 3-phenyl-1-butyn-3-ol, tetravinylcyclotetrasiloxane, octavinylcyclotetrasiloxane, maleate and triphenylphosphine oxide.

[0038] Preferably, the catalyst is 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex diluted with isopropanol, methyl silicone oil, vinyl silicone oil, or chloroplatinic acid diluted with isopropanol. The structural formula of the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex is as follows:

[0039] .

[0040] Preferably, the pigment can be an oily color paste containing pigment, a natural pigment or a synthetic pigment, such as cinnabar, red clay, realgar, malachite green, or a synthetic pigment such as red iron oxide, titanium white, iron blue, etc., which does not affect the performance of the catalyst.

[0041] A second aspect of the present invention provides a method for preparing a high foaming ratio liquid silicone rubber foam material, comprising the following steps:

[0042] Step 1: Weigh the base rubber, vinyl silicone oil, hydrogen silicone oil, flame retardant filler, and reinforcing filler in order by weight, stir and mix them for the first time, then add non-ionic silicone surfactant, foaming agent, auxiliary foaming agent, and inhibitor in order, stir at room temperature, stir and mix for the second time, then add the catalyst, and then stir and mix them for the third time to make them evenly mixed;

[0043] Step 2: Calendering the material in step 2, performing primary curing and secondary vulcanization to obtain a liquid silicone rubber foam material with a high foaming ratio.

[0044] Preferably, in step 1, the first stirring temperature is 20-40° C., and the time is 20-40 minutes; the second stirring temperature is 20-35° C., and the time is 10-15 minutes; and the third stirring time is 5 minutes.

[0045] Preferably, the curing temperature of the primary curing in step 2 is 100-120° C., and the curing time is 5-15 min; the curing temperature of the secondary curing is 190° C., and the curing time is 5-15 min.

[0046] The third aspect of the present invention provides an application of the high foaming ratio liquid silicone rubber foam material described in the first aspect. The high foaming ratio liquid silicone rubber foam material is used as a wrapping and sealing material in the field of power batteries, transportation tracks and / or electronic devices to play the role of sealing, waterproofing, heat insulation, fire prevention and buffering and shock absorption.

[0047] Compared with the prior art, the present invention has the following positive and beneficial effects:

[0048] (1) In this application, a water-based foaming system is selected, and a liquid base rubber is used as the raw material. Vinyl silicone oil and hydrogen-containing silicone oil are also liquids. The foaming process is carried out in a liquid environment. During the foaming process, part of the water is brought in by non-ionic polymer compounds, and part of the water is released by the condensation reaction of silanol in the foaming aid. The two work together to adjust the foaming ratio, making up for the unevenness of direct water-based foaming and the low foaming ratio of condensed water. At the same time, it also avoids the toxicity of chemical foaming agents, which is safe and environmentally friendly.

[0049] (2) The use of polyvinyl pyrrolidone non-ionic polymer compounds has a certain inhibitory effect on platinum catalysts, but does not affect high-temperature vulcanization. It is combined with acetylene alcohols, maleates or triphenylphosphine oxide compounds to synergistically inhibit the vulcanization rate and foaming rate, increase the operation time, avoid the vulcanization rate being too fast, resulting in the inability of bubbles to overflow, or mechanical stirring to damage the initiated bubbles before vulcanization, promote the uniformity of the bubbles, and increase the foaming ratio.

[0050] (3) This application uses a long-chain alkane-modified nonionic silicone surfactant, which enhances the compatibility between the foaming agent and the silicone oil, plays the role of emulsification, dispersion, and uniform foaming, avoids the collapse of the pores and continuous bubbles during the foaming process, and avoids the problem of uneven shrinkage and pore deformation of the material after secondary vulcanization and dehydration. At the same time, the long-chain alkane-modified nonionic silicone surfactant reduces the surface tension and enhances the demolding ability between the foaming silicone material and the release paper, does not stick to the film, and the surface of the foamed material after demolding is smooth.

[0051] (4) The foaming process of the present application is closed-cell foaming, the cells are uniform and not connected, and it has more excellent sealing, waterproof and heat insulation properties.

[0052] (5) During the secondary vulcanization process at 180-200°C of the foam material provided by the present application, the formed bubbles are not damaged, the process is smokeless and odorless, and the use of polyvinyl pyrrolidone avoids the adverse effects of material decomposition under high temperature conditions. At the same time, the foam material prepared by the present application has a low hardness, and the hardness Shore C is basically below 25, and some products can even reach below 10. DETAILED DESCRIPTION

[0053] The numbers and specifications of the reagents in the examples are shown in Table 1.

[0054] Table 1 Reagents

[0055]

[0056] Preparation:

[0057] (1) Preparation of base rubber:

[0058] Select the vinyl silicone oil with the structural formula (I) , vinyl content 0.38%, viscosity 10000cp 70 parts, specific surface area 200m 2 / g of fumed silica 30 parts and 1.5 parts of silazane, a structural control agent, are kneaded and mixed in a kneader. The mixture is heated to 150°C and kneaded for 2 hours. Then, 2 parts of water are added and neutralized for 1 hour. Subsequently, the small molecules in the base rubber are removed under vacuum conditions of -0.1MPa and 150°C. The mixture is cooled to below 40°C and sealed for storage.

[0059] (2) Preparation of nonionic silicone surfactant (Surf1):

[0060]

[0061] R1 is C12 alkyl, a=80, b=2, c=8, x=12, y=0

[0062] The preparation method is as follows:

[0063] The selected side hydrogen silicone oil structure is as follows:

[0064] The hydrogen content is 0.16%

[0065] Weigh 100g of hydrogenated silicone oil and 150g of isopropanol into a 500ml four-necked flask, pass cooling water, N2 protection, heat to 90°C, add 5ppm of Custer catalyst, mix for 2min, then drop 5.65g of 1-dodecene and allyl polyoxyethylene ether (structural formula: CH2=CHCH2O(C2H4O) 12 -H) 75g mixture was added dropwise, and the mixture was refluxed at 90℃ for 10h until a transparent system was formed, and the reaction was stopped. Isopropanol was distilled out under reduced pressure at 110℃ and vacuum degree of -0.1MPa, and the remaining substances in the reaction container were collected to obtain a transparent liquid non-ionic silicone surfactant Surf1 with an HLB value of 9.7.

[0066] (3) Preparation of nonionic silicone surfactant (Surf2):

[0067]

[0068] R1 is C8 alkyl, a=51, b=2, c=4, x=8, y=18

[0069] The preparation method is as follows:

[0070] The selected side hydrogen silicone oil structure is as follows:

[0071] The hydrogen content is 0.14%

[0072] Weigh 100g of hydrogenated silicone oil and 200g of isopropanol in a 500ml four-necked flask, pass cooling water, N2 protection, heat to 90°C, add 8ppm of Custer catalyst, mix for 2min, then drop 5.35g of 1-octene and allyl polyoxyethylene polyoxypropylene ether (structural formula: CH2=CHCH2O(C2H4O)8-(C3H6O) 18-CH3) 135.6g mixture was added dropwise, and the mixture was refluxed at 90℃ for 10h until a translucent system was formed, and the reaction was stopped. Isopropanol was distilled out under reduced pressure at 110℃ and vacuum degree -0.1MPa, and the remaining substances in the reaction container were collected to obtain a transparent liquid nonionic silicone surfactant Surf2. The HLB value was 3.75.

[0073] Example 1

[0074] The present embodiment provides a high foaming ratio liquid silicone rubber foam material, which is made of the following raw material components in parts by weight: 100 parts of base rubber, 22 parts of vinyl silicone oil 1#, 2.4 parts of hydrogen-containing silicone oil 1#, 60 parts of flame retardant filler 1#, 5.5 parts of reinforcing filler 2#, 3 parts of foaming agent 1#, 0.5 parts of auxiliary foaming agent 1#, 0.5 parts of non-ionic silicone surfactant 1#, 3 parts of non-ionic silicone surfactant 2#, 0.02 parts of inhibitor 1#, and 0.1 parts of catalyst 1#.

[0075] (1) Weigh the base rubber, vinyl silicone oil 1#, and hydrogen silicone oil 1# in parts by weight, add them to a planetary mixer, add flame retardant filler 1# and reinforcing filler 2# in turn, control the temperature below 40°C and start stirring. After mixing for 30 minutes, add non-ionic silicone surfactant 1#, non-ionic silicone surfactant 2#, foaming agent 1#, auxiliary foaming agent 1#, and inhibitor 1# in turn, stir at room temperature below 35°C for 10 minutes, stir evenly, add catalyst 1#, stir and mix for 5 minutes, then stop stirring and transfer the materials to the press.

[0076] (2) The material in the above (1) is calendered into a calender covered with release paper, calendered into shape, and then placed into a drying oven at 110° C. for curing for 10 minutes, and then the release papers on the upper and lower surfaces are peeled off to obtain a preliminarily vulcanized silicone foam material.

[0077] (3) The foamed silicone rubber in step (2) is placed in a drying oven at 190° C. for secondary vulcanization for 5 minutes, and then rolled up to obtain a high-stability, high-foaming-ratio liquid silicone rubber foam material.

[0078] Example 2

[0079] The content of a high foaming ratio liquid silicone rubber foam material is basically the same as that of Example 1, except that the amount of the foaming agent is increased, the amount of the foaming agent 1# is 6 parts, and the amount of the catalyst 2# is selected, and the amount is 0.3 parts.

[0080] Example 3

[0081] A high foaming ratio liquid silicone rubber foam material has basically the same content as that of Example 1, except that it is made of the following raw material components in parts by weight: 100 parts of base rubber, 10 parts of vinyl silicone oil 2#, 20 parts of vinyl silicone oil 3#, 8 parts of hydrogen-containing silicone oil 2#, 5 parts of hydrogen-containing silicone oil 3#, 90 parts of flame retardant filler 2#, 30 parts of flame retardant filler 3#, 10 parts of reinforcing filler 1#, 8 parts of reinforcing filler 2#, 2 parts of foaming agent 1#, 2.5 parts of auxiliary foaming agent 1#, 1 part of non-ionic silicone surfactant 1#, 2 parts of non-ionic silicone surfactant 2#, 0.05 parts of inhibitor 1#, and 0.5 parts of catalyst 1#.

[0082] Example 4

[0083] A high foaming ratio liquid silicone rubber foam material has basically the same content as that of Example 2, except that it is made of the following raw material components in parts by weight: 100 parts of base rubber, 25 parts of vinyl silicone oil 1#, 10 parts of vinyl silicone oil 3#, 18 parts of hydrogenated silicone oil 2#, 100 parts of flame retardant filler 2#, 7.5 parts of reinforcing filler 1#, 5 parts of foaming agent 2#, 2 parts of auxiliary foaming agent 2#, 3.5 parts of non-ionic silicone surfactant 2#, 0.08 parts of inhibitor 1#, and 1 part of catalyst 1#.

[0084] Example 5

[0085] The content of a high foaming ratio liquid silicone rubber foam material is basically the same as that of Example 4, except that the amount of reinforcing filler is increased, the amount of reinforcing filler 1# is 15 parts, and the amount of auxiliary foaming agent 2# is 4 parts.

[0086] Example 6

[0087] A high foaming ratio liquid silicone rubber foam material has basically the same content as that of Example 1, except that it is made of the following raw material components in parts by weight: 100 parts of base rubber, 20 parts of vinyl silicone oil 1#, 10 parts of vinyl silicone oil 2#, 1.5 parts of hydrogen-containing silicone oil 1#, 8 parts of hydrogen-containing silicone oil 2#, 55 parts of flame retardant filler 1#, 30 parts of flame retardant filler 3#, 8 parts of reinforcing filler 1#, 10 parts of reinforcing filler 2#, 6 parts of foaming agent 1#, 2 parts of auxiliary foaming agent 1#, 3 parts of auxiliary foaming agent 2#, 1.5 parts of non-ionic silicone surfactant 1#, 3.5 parts of non-ionic silicone surfactant 2#, 0.1 parts of inhibitor 2#, and 0.55 parts of catalyst 2#.

[0088] Example 7

[0089] A high foaming ratio liquid silicone rubber foam material has basically the same content as that of Example 2, except that it is made of the following raw material components in parts by weight: 100 parts of base rubber, 50 parts of vinyl silicone oil 1#, 6.5 parts of hydrogen-containing silicone oil 3#, 50 parts of flame retardant filler 1#, 65 parts of flame retardant filler 2#, 15 parts of reinforcing filler 2#, 6 parts of foaming agent 2#, 1 part of auxiliary foaming agent 1#, 1.5 parts of non-ionic silicone surfactant 2#, 0.06 parts of inhibitor 1#, and 0.8 parts of catalyst 1#.

[0090] Performance Test:

[0091] Hardness: GBT27570-2011 "Room Temperature Vulcanized Methyl Silicone Rubber" test standard, GB / T 531.1 "Vulcanized Rubber or Thermoplastic Rubber" indentation hardness test method, test the hardness of foam materials. The foam is calendered and vulcanized, and a 6mm thick sample is selected, cut into a 6×6cm sample with a length and width, and the Shore C hardness is tested using a Shore durometer; if it is less than 6mm, fold it into a 6mm thick sample to test the Shore C hardness.

[0092] Tensile strength, elongation: GB / T1701-2001 "Determination of tensile strength and elongation at break of hard rubber" standard tests the tensile strength and elongation at break of foam materials.

[0093] Apparent density: GB / T 533-2008 "Test density of vulcanized rubber or thermoplastic rubber" standard tests the density of foam materials.

[0094] Foaming ratio: Pour the silicone rubber foaming composition material stirred after adding the catalyst component into a graduated measuring cup quickly, record the material height L0, and record the material height L1 after foaming is complete. Calculate L1 / L0 to be the foaming ratio of the silicone foam material.

[0095] Flame retardant test: UL94-2009 "Flammability Test for Plastic Materials for Equipment and Appliance Components" standard tests flame retardant properties.

[0096] The performance test data of Examples 1 to 7 are shown in Table 2.

[0097] Table 2 Performance of foaming materials in Examples 1 to 7

[0098]

[0099] As can be seen from Table 2, the high foaming ratio liquid silicone rubber foam material prepared by the present invention has a high foaming ratio, fine pores, uniform size, a foaming ratio of up to 7.97 times, and a reduced hardness, especially the hardness of Examples 2 and 6 can be as low as 8, and the density of Example 5 can be reduced to 0.187 g / cm 3, which can achieve the lightweight requirements of foam materials.

[0100] In Examples 1 and 2, increasing the amount of foaming agent can increase the foaming ratio and obtain a lower density and softer foam material, but after the hardness is reduced, the tensile strength of the material is reduced. In Examples 4 and 5, increasing the amount of reinforcing filler can improve the tensile strength of the foam material to a certain extent. When the addition amounts of all other components are the same, adding reinforcing filler reduces the viscosity of the composition, improves the operability of the rubber composition, is beneficial to the uniformity of the foam cells, and can increase the foaming ratio. It can be seen from Examples 1 to 7 that increasing the amount of flame retardant filler can improve flame retardancy and reduce combustion extinguishing time. In Example 3, the relative percentage of flame retardant filler is the highest, and its flame retardant effect is the best.

[0101] Comparative Example 1

[0102] The content of a liquid silicone rubber foam material is substantially the same as that of Example 1, except that no foaming agent and auxiliary foaming agent are added.

[0103] Comparative Example 2

[0104] The content of a liquid silicone rubber foam material is substantially the same as that of Example 1, except that no foaming aid is added.

[0105] Comparative Example 3

[0106] The content of a liquid silicone rubber foam material is substantially the same as that of Example 1, except that no foaming agent is added.

[0107] The performance of the samples prepared in Comparative Examples 1 to 3 was tested, and the test results are shown in Table 3.

[0108] Table 3 Performance of foaming materials of Comparative Examples 1 to 3 and Example 1

[0109]

[0110] The difference between comparative examples 1 to 3 and embodiment 1 is that comparative example 1 does not add a foaming agent and an auxiliary foaming agent; comparative example 2 only adds a foaming agent and 0 component auxiliary foaming agent; comparative example 3 adds an auxiliary foaming agent and 0 component foaming agent. Through the test results in Table 3, we found that: without adding any foaming agent, only adding a foaming agent or only adding an auxiliary foaming agent, a foam material with a high foaming ratio cannot be obtained, and the obtained material has a high hardness and density, which is not conducive to the application of lightweight.

[0111] Comparative Example 4

[0112] The content of a liquid silicone rubber foam material is substantially the same as that of Example 3, except that the amount of the foaming agent is reduced to 0.2 parts. The test results are shown in Table 4.

[0113] Table 4 Performance of foamed materials of Comparative Example 4 and Example 3

[0114]

[0115] Comparative Example 4 is based on Example 3, and the amount of the foaming agent is reduced to 0.2 parts, which is lower than the weight parts specified in the present invention. Through the test results in Table 4, we found that: reducing the amount of the foaming agent, the foaming ratio is reduced, the material density is increased, and the application degree is limited.

[0116] Comparative Example 5

[0117] The content of a liquid silicone rubber foam material is substantially the same as that of Example 5, except that no nonionic silicone surfactant is added.

[0118] Comparative Example 6

[0119] The content of a liquid silicone rubber foam material is substantially the same as that of Example 6, except that no reinforcing filler is added.

[0120] Comparative Example 7

[0121] The content of a liquid silicone rubber foam material is substantially the same as that of Example 5, except that a conventional nonionic surfactant Span 80 is added in an amount of 3.5 parts. The test results are shown in Table 5.

[0122] Table 5 Performance of foamed materials of Comparative Examples 5 to 7 and Example 5

[0123]

[0124] Comparative Example 5 is based on Example 5, but no nonionic silicone surfactant is added. Through the test results in Table 5, we found that without the effect of nonionic silicone surfactant, the compatibility of the water system with silicone oil deteriorates, and the foaming is uneven; without the uniform foaming effect of nonionic silicone surfactant, the cell collapses seriously, and the demoulding difficulty is increased, and the release force increases, which is not conducive to production.

[0125] Compared with Example 6, Comparative Example 6 does not add reinforcing filler. From solid silica gel to foamed material, it can be known through experiments that the smaller the density, the smaller the tensile strength of the foamed material, which is not conducive to the application of the foamed material. Comparative Example 6 does not add reinforcing filler. Although the foaming ratio is high and the density is low, the tensile strength is reduced, which is not conducive to practical application.

[0126] Comparative Example 7 uses conventional surfactant Span80 to replace the nonionic surfactant specified in the patent, which reduces the compatibility of the aqueous foaming agent with the silicone material, resulting in uneven pores, which is not conducive to foaming. At the same time, it increases the release force between the foaming material and the release paper, making it difficult to demold, which is not conducive to production.

[0127] Comparative Example 8

[0128] The content of a liquid silicone rubber foam material is substantially the same as that of Example 6, except that the amount of the flame retardant filler is reduced to 20 parts.

[0129] Comparative Example 9

[0130] The content of a liquid silicone rubber foam material is substantially the same as that of Example 6, except that the amount of the flame retardant filler is increased to 155 parts. The test results are shown in Table 6.

[0131] Table 6 Performance of foamed materials of Comparative Examples 8 to 9 and Example 6

[0132]

[0133] Comparative Example 8, on the basis of Example 6, reduces the amount of flame retardant filler to 20 parts, which is lower than the weight parts specified in the present invention. Through the test results of Table 6, we found that after reducing the amount of flame retardant filler, the pore situation is not affected, the foaming is still uniform, and the pores are fine, but the flame retardant performance and hardness are reduced, and the V~0 level cannot be reached. Comparative Example 9, on the basis of Example 6, increases the amount of flame retardant filler to 155 parts, and the flame retardant effect is significantly improved. However, due to the large amount of powder, the viscosity of the silicone rubber composition increases, the operability is reduced, which is not conducive to the uniformity of the pores, thereby reducing the tensile strength of the material. At the same time, the foaming ratio of the material is also reduced.

[0134] Comparative Example 10

[0135] A liquid silicone rubber foam material has substantially the same content as that of Example 7, except that no inhibitor is added.

[0136] Table 7 Performance of foamed materials of Comparative Example 10 and Example 7

[0137]

[0138] Comparative Example 10 is based on Example 7, but no inhibitor is added. Through the test results in Table 7, we found that without the effect of the inhibitor, when the catalyst is added to the system, the foaming rate and the vulcanization speed are carried out simultaneously. During the stirring process, the vulcanization is too fast, which is not conducive to the formation of fine pores; at the same time, without the inhibitor, the pores initiated during the foaming process are destroyed by mechanical stirring when there is no vulcanization to form a stable structure, and secondary foaming cannot be carried out, which is not conducive to the formation of uniform pores and cannot obtain high foaming ratio materials. Finally, without the presence of the inhibitor, curing before calendering or during stirring will damage the equipment and be unfavorable for production.

[0139] This low-density silicone foam material can be used in new energy vehicle power batteries, transportation tracks and other fields due to its lightweight, high temperature resistance, sound insulation, heat insulation, sealing and waterproofing. Specifically, it can be used for thermal insulation foam pipes for automobile air conditioners, automobile shock absorption, and sealing and buffering protection of new energy vehicle batteries. It can also be used to fill light leakage, prevent pollution, absorb impact and improve sealing around LEDs.

Claims

1. A high foaming ratio liquid silicone rubber foam material, characterized in that: The invention is mainly made of the following raw material components in parts by weight: 100 parts of base rubber, 20-50 parts of vinyl silicone oil, 1-20 parts of hydrogenated silicone oil, 5-20 parts of reinforcing filler, 60-120 parts of flame retardant filler, 1-6 parts of foaming agent, 1-5 parts of non-ionic silicone surfactant, 0.5-5 parts of auxiliary foaming agent, 0.02-0.1 parts of inhibitor, 0.1-1 parts of catalyst, and 0-20 parts of pigment; the HLB value of the non-ionic silicone surfactant is 1-10, and its structure is: Wherein R1 is a C6-18 alkane, a is an integer of 10-100, b is an integer of 1-8, and c is an integer of 2-20; x is an integer of 2-20, and y is an integer of 0-20; R2 is hydrogen, methyl or butyl; the foaming agent is a non-ionic polymer powder with a water content of 80%-99%, and the non-ionic polymer is a polyvinyl pyrrolidone polymer with a molecular weight of 30,000-80,000; the base rubber is mainly kneaded by vinyl silicone oil, white carbon black and a structuring control agent; the auxiliary foaming agent is an organic silanol; the inhibitor is at least one of an acetylenic alcohol compound, a polyvinyl compound, a maleate compound, and triphenylphosphine oxide; the catalyst is isopropyl alcohol, methyl silicone oil, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex diluted with vinyl silicone oil, or chloroplatinic acid diluted with isopropyl alcohol.

2. The high foaming ratio liquid silicone rubber foam material according to claim 1, characterized in that: The structure of the vinyl silicone oil is: 、 or Wherein R1, R2, R3 are independently methyl, ethyl, and phenyl respectively; m is an integer from 10 to 10,000, x is an integer from 2 to 100, y is an integer from 10 to 10,000, and n is an integer from 2 to 100.

3. The high foaming ratio liquid silicone rubber foam material according to claim 2, characterized in that: The reinforcing filler is at least one of methyl MQ resin, vinyl MQ resin and methyl phenyl MQ resin; and the flame retardant filler is halogen-free flame retardant powder.

4. The high foaming ratio liquid silicone rubber foam material according to claim 3, characterized in that: The halogen-free flame retardant powder is at least one of aluminum hydroxide, surface-modified aluminum hydroxide, and melamine cyanurate MCA; the organic silanol is at least one of trimethyl silanol, triethyl silanol, diethyl disilanol, dimethyl phenyl silanol, and triphenyl silanol.

5. The method for preparing a high foaming ratio liquid silicone rubber foam material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Weigh the base rubber, vinyl silicone oil, hydrogen silicone oil, flame retardant filler, and reinforcing filler in order by weight, stir and mix them for the first time, then add non-ionic silicone surfactant, foaming agent, auxiliary foaming agent, and inhibitor in order, stir at room temperature, stir and mix for the second time, then add the catalyst, and then stir and mix them for the third time to make them evenly mixed; Step 2: Calendering the material in step 1, performing primary curing and secondary vulcanization to obtain a liquid silicone rubber foam material with a high foaming ratio.

6. The method for preparing a high foaming ratio liquid silicone rubber foam material according to claim 5, characterized in that: The curing temperature of the primary curing is 100-120°C, and the curing time is 5-15 minutes; the curing temperature of the secondary curing is 190°C, and the curing time is 5-15 minutes.

7. Use of the high foaming ratio liquid silicone rubber foam material according to any one of claims 1 to 4 in the fields of power batteries, transportation tracks and / or electronic devices.

Images