A low-smoke, non-flammable perfluororubber foam composition, foam and preparation method thereof

Abstract

The present invention relates to the technical field of foaming products, and in particular to a low-smoke, non-flammable perfluororubber foam composition, a foam and a preparation method thereof. The raw materials of the low-smoke, non-flammable perfluororubber foam composition include: 100 parts of perfluororubber; 8 to 40 parts of nano-β-silicon nitride; 5 to 30 parts of fumed silica; and 0 to 2 parts of a foaming promoter. The total amount of added nano-β-silicon nitride and fumed silica is not higher than 50 parts; the foam formed by the perfluororubber foam composition has a foaming ratio higher than 50%, and the perfluororubber foam has a foaming ratio of 50KW / m 2 It is non-flammable under the irradiation of radiant heat sources, TTI is greater than 300 seconds, and the total smoke release is less than 100m 2 / m 2 .

Description

Technical Field

[0001] The invention relates to the technical field of foam products, and in particular to a low-smoke-releasing, non-flammable perfluororubber foam composition, a foam and a preparation method thereof. Background Art

[0002] There are relatively few reports on fluororubber foaming in the prior art. So far, the reported processes for rubber foaming mainly include: supercritical physical foaming method, conventional inorganic or organic compound chemical foaming agents, etc. The former requires specific supercritical equipment and high-pressure injection of physical foaming gas. The pressure during the foaming process reaches 5-6MPa, and the equipment investment cost and operating cost are relatively high. In the case of using chemical foaming agents for foaming, most of the gases produced by inorganic foaming agents contain carbon dioxide, water vapor, ammonia, etc., instead of nitrogen, so they will produce pungent odors or environmentally unfriendly gases. At present, this type of foaming agent is mainly used for foaming products with open-cell structures, and the gas generation of inorganic foaming agents is unstable, making it difficult to obtain products with high foaming ratios. The use of organic compounds for foaming is now a commonly used method. It is easy to use and it is easy to obtain high-quality sponges. Organic foaming agents have a large amount of gas release, and the released gas is mainly nitrogen. However, most products are flammable, and the remaining part after the gas is released will have residual odor, toxicity and environmental pollution problems. Some organic foaming agents even require the addition of various types of foaming aids such as metal salts and metal oxides.

[0003] In the previous application CN2023117421755, a foamable perfluororubber formula composition and its products were announced. The inventor applied for a composition of cyanide-containing perfluororubber and nano-β-silicon nitride to form a perfluororubber foam. In this composition, in order to adjust the foaming rate of the composition, different types of foaming promoters can be added. According to the difference in the promotion effect of the foaming promoter, the amount of promoter added is also different. Among them, when inorganic ammonium salts and organic ammonium salts are used as foaming promoters, there are problems such as unstable decomposition temperature of ammonium salts and unstable amount of effective gas produced during decomposition. The foaming quality is difficult to control, and it is also difficult to obtain foaming products with high foaming rates. When amine compounds are selected as foaming promoters, the foaming ratio is easier to achieve by selecting the type of amine compounds and regulating the corresponding appropriate dosage.

[0004] Perfluororubber foams with a relatively low foaming ratio (<50%) have a relatively high relative specific gravity. After the combustion performance test using a cone calorimeter, it was found that their total smoke release was relatively large. The foam formed by the perfluororubber composition using amine compounds as the foaming promoter also shows an upward trend in total smoke release as the amount of amine compounds added increases. This is because most amine compounds contain structures such as aliphatic hydrocarbon groups or aromatic ring hydrocarbon groups. Due to their high carbon content, these structures are prone to form carbon particles after dehydration and deamination due to reactions such as cyclization and polycondensation during combustion, causing the problem of increased smoke release. Therefore, in order to reduce the smoke production during the combustion of perfluoro foams, it is necessary to increase the foaming ratio of perfluororubber foams and also reduce the amount of foaming promoters as much as possible. Foaming materials are usually used in the fields of heat insulation, sound insulation, insulation, lightweighting, etc. Their foaming ratio and combustion performance, including ignition time TTI, total smoke release, etc., are important indicators that affect their usability and safety.

[0005] When selecting an amine compound foaming promoter with a slower ammonia generation rate, a relatively high addition amount is often required to achieve a higher foaming ratio. For example, for a benzyl carbamate foaming promoter, at least 5 parts of addition amount is generally required to obtain a foaming ratio higher than 50%. At the same time, in order to reduce the amount of smoke generated during combustion of the foam, the addition amount is required to be as small as possible. How to effectively balance the contradiction between the amount of foaming promoter used and the total smoke production during combustion is an urgent problem to be solved.

[0006] Moreover, in subsequent experimental studies, it was found that due to the stability of the mixing and molding process, differences in mold processing methods and other reasons, the same foaming formula combination may result in significantly different final foaming rates. In severe cases, it may even lead to serious poor foaming, with the foaming rate approaching 0. How to reduce the sensitivity of the perfluororubber foaming combination formula to influencing factors such as process parameters, improve operability and stability during production, and reduce the performance differences between foams with the same formula are issues that need to be further addressed. Summary of the invention

[0007] In view of the shortcomings of the prior art, the object of the present invention is to provide a low-smoke, non-flammable perfluororubber foam composition, a foam and a preparation method thereof, so as to solve the problems of low foaming ratio or high smoke release during combustion in some existing formula combinations.

[0008] The present invention provides a low-smoke-releasing, non-flammable perfluororubber foam composition, wherein the raw materials of the low-smoke-releasing, non-flammable perfluororubber foam composition include:

[0009] 100 parts of perfluoro rubber;

[0010] 8-40 parts of nano-β-silicon nitride;

[0011] 5-30 parts of fumed silica;

[0012] Foaming promoter 0-2 parts.

[0013] The total amount of nano-β-silicon nitride and fumed silica added is not more than 50 parts, more preferably not more than 45 parts;

[0014] The foamed body formed by the perfluororubber foamed body composition has a foaming ratio higher than 50%.

[0015] Among them, the perfluoro rubber is a perfluoro rubber containing cyano groups, the cyano groups can be located at the side chain or the end of the macromolecular chain, and the Mooney viscosity ML (1+10) @ 121°C of the perfluoro rubber is 20 to 95, preferably 30 to 80. Too large or too small Mooney viscosity is not conducive to the formation of a good foaming structure of the foam.

[0016] The size of the nano-β-silicon nitride is 500 nm or less, preferably 20 nm to 500 nm, and more preferably 20 to 100 nm.

[0017] The BET surface area of ​​fumed silica is ≥50m 2 / g, more preferably ≥80m 2 / g.

[0018] The present invention also provides a method for preparing the low-smoke, non-flammable perfluororubber foam composition described in the first aspect of the present invention, the preparation method comprising: evenly mixing perfluororubber, nano-β-silicon nitride and fumed silica under heating conditions, and then gradually adding a foaming promoter multiple times in an open mill to obtain a low-smoke, non-flammable perfluororubber foam composition.

[0019] The present invention also provides a foam, which is prepared by a one-step foaming or multi-step foaming method using the aforementioned low-smoke, non-flammable perfluororubber foam composition, wherein the foaming process of the low-smoke, non-flammable perfluororubber foam includes a primary vulcanization molding under heating and pressure, and then a secondary vulcanization, wherein the secondary vulcanization process makes the foaming more complete and obtains a perfluororubber foam with a final fixed shape.

[0020] The present invention also provides the use of the low-smoke, non-flammable perfluororubber foam composition and / or the foam in the fields of electronics, electrical engineering, aerospace, semiconductors, machinery, and packaging.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention provides a low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam. In the formulation of the present invention, on the basis of adding no or little foaming accelerator, by adding fumed silica, the foaming rate of the perfluororubber foam reaches more than 50%, and the perfluororubber foam has a thermal conductivity of 50KW / m 2 It is non-flammable under the irradiation of radiant heat sources, TTI is greater than 300 seconds, and the total smoke release is less than 100m 2 / m 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Shown are the thermal gravimetric analysis and corresponding c-DTA analysis graphs of perfluororubber foaming compositions (both components contain cyanide-containing FFKM and a certain proportion of nano-β-silicon nitride) without the addition of fumed silica (green) and with the addition of fumed silica (red) in air atmosphere.

[0024] Figure 2 Shown is a cross-sectional view of the foam of the perfluororubber foam composition of the present invention, wherein the upper figure is Comparative Example 3 and the lower figure is Example 2.

[0025] Figure 3 Shown is a cross-sectional view of the foam of the perfluororubber foam composition of the present invention, wherein the upper figure is comparative example 4 and the lower figure is example 3.

[0026] Figure 4 Shown is a cross-sectional view of the foam of the perfluororubber foam composition of the present invention, wherein the upper figure is comparative example 5 and the lower figure is example 7. DETAILED DESCRIPTION

[0027] The following describes in detail embodiments of a low-smoke, non-flammable perfluororubber foam composition, a foam, and a method for preparing the same.

[0028] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0029] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0030] After a lot of experimental research, the inventors found that when a certain amount of inorganic nano-β-silicon nitride is added to the cyanide-containing perfluororubber, certain chemical reactions will occur during the processing and vulcanization of the perfluororubber to produce gas. The main component of this gas has been proven to be nitrogen through testing and analysis, thereby forming a foamed product of perfluororubber. The specific content has been described in detail in CN2023117421755.

[0031] The main feature of the present invention is that when a foam is prepared from a mixture of cyano perfluoro rubber and β-silicon nitride, the amount of foaming promoter added is limited due to the amount of smoke generated during combustion, requiring less or no addition, or the total foaming rate of the perfluoro rubber foam is less than 50% due to the process stability and viscosity differences caused by the fluctuation of the molecular weight of the raw rubber due to the stability of the batch of raw materials during the production process, which will also lead to the problem of high smoke generation during combustion, and cannot meet the requirements of heat insulation, buffering, etc. The applicant found in the experiment that by adding fumed silica to the composition, the foaming behavior of the perfluoro rubber foam composition can be greatly improved, and the foaming rate can reach more than 50%. At the same time, the addition of fumed silica can also reduce the total smoke release of the perfluoro rubber foam during combustion, greatly improving the safety of use.

[0032] The applicant tried to explain the reason why fumed silica promotes the foaming of perfluororubber compositions by thermogravimetric analysis combined with its c-DTA analysis function. The thermogravimetric analysis of perfluororubber foaming compositions without and with silica (the components all contain cyanide-containing FFKM and a certain proportion of nano-β-silicon nitride) was performed in air. Figure 1 It can be seen that during the heating process, before 420°C on the thermal weight loss curve, both components have two obvious weight loss areas, corresponding to two obvious exothermic peaks, indicating that the formula combination undergoes a certain reaction to generate gas and foaming. The peak area and peak height of the two exothermic peaks of the formula combination with white carbon black are significantly greater than those of the formula combination without white carbon black. Accordingly, the final foaming rate of the formula combination containing white carbon black is about 51.4%, while the final foaming rate of the formula combination without white carbon black is about 6.1%. In this component, gas phase white carbon black can be understood as promoting the heat release of the foaming reaction to make the gas expand more quickly and fully, and ultimately increase the foaming rate. At this time, the number of cells in the foam body remains almost unchanged, and the volume of the cells increases. Figure 2 Cross-sectional view of the foam.

[0033] When the content of nano-β-silicon nitride is low, or the amount of foaming promoter added is small, or the type and characteristics of the foaming promoter are selected so that its foaming efficiency for the foaming composition of nano-β-silicon nitride and cyanide-containing perfluororubber is not high, and when the foaming is poor and the foaming rate is low due to factors such as fluctuations in raw rubber, differences in mixing process or molding process, etc., adding a certain amount of fumed silica can eliminate the influence of the above factors and obtain a perfluororubber foam with a foaming rate of more than 50%, and this perfluororubber foam has non-flammability and low smoke release.

[0034] For a perfluororubber composition containing a foaming accelerator and having a high foaming ratio, the addition of white carbon black has little effect on improving the foaming ratio, but can reduce the total smoke release of the foam.

[0035] In summary, the purpose of the present invention is to provide a low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam. To achieve this purpose and its associated target performance, one aspect of the present invention provides a low-smoke, non-flammable perfluororubber foam composition, the raw materials of which include perfluororubber raw rubber, nano-β-silicon nitride and fumed silica, and optionally, a foaming accelerator, other reinforcing fillers or high-temperature resistant pigments.

[0036] In the perfluoro rubber foam composition provided by the present invention, the weight portion of the perfluoroether rubber is 100 parts. The perfluoro rubber contains a cyano group, which can be located at the end of the main chain or at the side chain. Optionally, the cyano group is introduced by polymerizing a cross-linking point monomer containing a cyano group with tetrafluoroethylene, perfluoroalkyl vinyl ether (PMVE) or perfluoroalkoxy vinyl ether (PAAVE for short) to form a copolymer.

[0037] Further, the Mooney viscosity ML (1+10) @ 121°C of the cyanide-containing perfluororubber is 20 to 95. Optionally, the Mooney viscosity ML (1+10) @ 121°C of the cyanide-containing perfluororubber can be, for example, 20 to 30, 30 to 80, 30 to 50, 50 to 80 or 80 to 95, etc. Preferably, it is 30 to 80.

[0038] In the low-smoke, non-flammable perfluororubber foam composition provided by the present invention, nano β-silicon nitride is both a vulcanizing agent for perfluororubber and a component of a foaming agent. The specific foaming process and the type of gas generated during the foaming process have been analyzed in CN2023117421755. Based on 100 parts by weight of perfluororubber raw rubber, the weight of the nano β-silicon nitride is 8 to 40 parts. Optionally, the weight of the β-silicon nitride can be, for example, 8 to 10 parts, 10 to 30 parts, 30 to 40 parts, 10 to 25 parts, 8 to 15 parts, 15 to 30 parts, 30 to 40 parts, 8 to 12 parts, 12 to 15 parts, 15 to 20 parts, 20 to 25 parts, 25 to 30 parts, 30 to 35 parts, 35 to 40 parts or 15 to 25 parts, etc. Preferably, the weight proportion of the nano-β-silicon nitride can be, for example, 10 to 30 parts. More preferably, the weight proportion of the nano-β-silicon nitride can be, for example, 10 to 25 parts. Within the above weight proportions, the advantage is that it is relatively easy to form a foamed perfluororubber product. The disadvantage of too many weight proportions is that the fluidity of the rubber material is poor when the total proportion of fillers is high, and it is easy to cause appearance defects such as unevenness, pits and other poor appearance phenomena during compression molding. The generated gas is easy to escape through the pits, affecting the film to form a good wrapping of the gas, and ultimately affecting the foaming effect; the disadvantage of too small weight proportions is that the amount of effective gas that really acts on the foaming process generated by the entire rubber material during the vulcanization process is too small, and it is difficult to produce a foamed product. The effective gas here mainly refers to the foaming gas generated in the process-nitrogen.

[0039] In the low-smoke, non-flammable perfluororubber foam composition provided by the present invention, the particle size of the nano β-silicon nitride can be 500nm or less, and the lower limit is not particularly limited. Optionally, the particle size of the β-silicon nitride can be 400nm or less, 300nm or less, 200nm or less, 100nm or less, 0-1nm, 1nm to 500nm, 1nm to 20nm, 20nm to 500nm, 1nm to 5nm, 5nm to 20nm, 20nm to 100nm, 100nm to 200nm, 200nm to 300nm, 300nm to 400nm, 400nm to 500nm. Preferably, the particle size of the nano β-silicon nitride is 20nm to 500nm. Further preferably, the particle size of the nano β-silicon nitride can be 100nm or less, for example, 20nm to 100nm. The above-mentioned nano-scale β-silicon nitride can only generate a large amount of gas when mixed with nitrile-containing perfluororubber under processing and molding conditions, while micron-scale β-silicon nitride will form a relatively stable rubber product.

[0040] In the low-smoke, non-flammable perfluororubber foam composition provided by the present invention, the weight portion of fumed silica is 5 to 30 parts. Optionally, the weight portion of fumed silica can be, for example, 5 to 8 parts, 8 to 15 parts, or 15 to 30 parts, etc. Preferably, it is 8 to 15 parts.

[0041] Furthermore, the BET surface area of ​​fumed silica is ≥50 m 2 / g. Preferably, the BET surface area of ​​fumed silica is ≥80m 2 / g.

[0042] In the low-smoke, non-flammable perfluororubber foam composition provided by the present invention, the total weight of nano-β-silicon nitride and fumed silica is not more than 50 parts. Preferably, the total weight of the nano-β-silicon nitride and fumed silica is not more than 45 parts.

[0043] In the low-smoke, non-flammable perfluororubber foam composition provided by the present invention, the weight of the foaming promoter can be, for example, 0 to 2 parts, based on 100 parts by weight of the perfluororubber raw rubber. Alternatively, the weight of the foaming promoter can be, for example, 0.2 to 1.8 parts, 0.5 to 1.8 parts, 0 to 0.5 parts, 0.5 to 1 parts, or 1 to 2 parts. Optionally, based on 100 parts by weight of the perfluororubber raw rubber, the weight of the compound that generates ammonia by thermal decomposition at a temperature of 150 to 300° C. is 0 to 2 parts, preferably 0.2 to 1.8 parts, and more preferably 0.5 to 1.8 parts. Further optionally, the weight proportion of the amine compound can be, for example, 0.2-1.8 parts, 0.5-1.8 parts, 0-1 parts, 0-0.5 parts, 0.5-1 parts, 1-2 parts, etc. Depending on the type of the foaming promoter, the preferred addition proportion will also be different.

[0044] On the basis of using fumed silica to increase the foaming rate of perfluororubber foam, the amount of smoke generated by perfluororubber foam during combustion is also reduced. Moreover, the use of fumed silica can also help optimize the screening process of foaming promoters. Ammonia-producing compounds can be added to perfluororubber foam compositions as foaming promoters, but the differences in the types, structures and properties of foaming promoters result in great differences in their foaming effects and optimal dosages, which poses great difficulties for the continuous optimization of the stability and performance of foamed products. For example, when adding foaming promoters such as benzyl carbamate or phthalamide without adding silica, the foaming rate of the composition is low, and the morphology and size of the bubbles are uneven. After adding silica, the foaming rate increases, and the differences in the shape and size characteristics of the bubbles are more obvious. The foaming states of the two are quite different, such as Figure 3 (Top: Comparative Example 3 / Bottom: Example 2) and Figure 4 (Top: Comparative Example 4 / Bottom: Example 3), Figure 3 After adding fumed silica, the foamed body mainly showed an increase in the size of the pores, but no significant increase in the number of pores. Figure 4 After adding fumed silica, the foamed body showed an increase in the number of cells and the size of the cells. Therefore, the combination of fumed silica and different accelerators has different promoting effects on the foaming process of perfluororubber foam.

[0045] Optionally, the promoter may be a compound that can produce ammonia by thermal decomposition at a temperature of 150 to 300°C. Optionally, the foaming promoter is an amine compound. Further optionally, the compound that produces ammonia by thermal decomposition at a temperature of 150 to 300°C may be selected from urea and urea derivatives and amine compounds that are usually used as crosslinking agents or promoters for cyano-containing perfluoro rubber. Urea and urea derivatives and the above-mentioned amine compounds have obvious effects on adjusting the foaming ratio, the size, number and shape of the foam cells, and affecting the foaming speed. Different compounds have great differences in affecting the foaming effect.

[0046] Further, the amine compound can be selected from one or more of urea and urea derivatives, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (BOAP), acetaldehyde amine, hexamethylenediamine, formamidine, 1,8-diazabicycloundec-7-ene (DBU), carbamate compounds and phthalamide. The carbamate compound is selected from one or more of benzyl carbamate, butyl carbamate, tert-butyl carbamate, N-(benzyloxy)amino tert-butyl ester, methyl-tert-butyl carbamate, benzyl carbamate, etc. Urea and urea derivatives are selected from one or more of biuret, thiourea, alkyl urea, ureide, etc. Further preferably, the foaming promoter is alkyl urea.

[0047] Furthermore, according to the specific foaming rate, requirements of the foaming structure, and requirements of the combustion performance of the perfluororubber foam, etc., the appropriate type of foaming promoter and the appropriate amount of addition are selected. Based on 100 parts by weight of the perfluororubber raw rubber, the weight of the amine compound can be, for example, 0 to 2 parts, and optionally, the weight of the amine compound or urea and urea derivatives can be, for example, 0 to 0.2 parts, 0.2 to 0.5 parts, or 0.5 to 2 parts. Preferably, the weight of the amine compound or urea / urea derivatives can be, for example, 0.5 to 1.8 parts.

[0048] The low-smoke, non-flammable perfluororubber foam composition provided by the present invention also includes other reinforcing fillers or contains high temperature resistant pigments. Wherein, the other reinforcing fillers include inorganic fillers and / or organic fillers. Preferably, the inorganic filler is selected from one or more of fillers such as carbon black, carbon fiber, carbon nanotubes, alumina, nitride, carbide, silicate, barium sulfate, etc.; the organic reinforcing material is selected from one or more of polyamide, polyimide, polyphenylene sulfide, polyether sulfone, polyetherimide, polyether ether ketone, polytetrafluoroethylene powder, etc. Optionally, other reinforcing fillers can be, for example, PTFE powder and / or carbon nanotubes.

[0049] Based on 100 parts by weight of the raw perfluororubber, the weight of the other reinforcing fillers is 0 to 30 parts. Optionally, the weight of the other reinforcing fillers can be, for example, 0 to 5, 5 to 10, 10 to 15, 15 to 20, 20 to 25, 0 to 20, 0 to 15, 0 to 10 or 0 to 5 parts.

[0050] In the perfluororubber-based foamable composition provided by the present invention, the foamable composition further comprises a high temperature resistant pigment. Preferably, the high temperature resistant pigment is selected from one or more of amine pigments, oxide pigments, metal pigments and carbon black pigments.

[0051] Based on 100 parts by weight of the raw perfluororubber, the weight of the high temperature resistant pigment is 0 to 10 parts. Optionally, the weight of the high temperature resistant pigment is 0 to 1 part, 1 to 3 parts, 3 to 5 parts, 5 to 8 parts, 8 to 10 parts, 1 to 5 parts, 5 to 10 parts, 0 to 8 parts, 0 to 6 parts, 0 to 4 parts, 0 to 2 parts, etc.

[0052] After adding other reinforcing fillers or various high temperature resistant pigments, the strength and color of the foamed structure can be properly adjusted without affecting the original foaming rate.

[0053] In one specific embodiment of the present invention, the raw materials of the foamable composition include:

[0054] 100 parts of perfluoro rubber;

[0055] 8-40 parts of nano-β-silicon nitride;

[0056] 5-30 parts of fumed silica;

[0057] Foaming promoter 0-2 parts.

[0058] The total amount of nano-β-silicon nitride and fumed silica added is not more than 50 parts, more preferably not more than 45 parts;

[0059] In the low-smoke-releasing, non-flammable perfluororubber foam composition provided by the present invention:

[0060] The perfluororubber foam formed by the foamable composition has excellent chemical resistance and solvent resistance, and its foaming rate is greater than 50%. Optionally, its foaming rate is greater than 50% and less than 98%. Optionally, its foaming rate is greater than 60%, its foaming rate is greater than 70%, its foaming rate is greater than 80%, and its foaming rate is greater than 90%. Further optionally, the foaming rate of the foamable composition is greater than 50% and less than 98%; greater than 60% and less than 98%; greater than 70% and less than 98%; greater than 80% and less than 98%; or greater than 90% and less than 98%, etc.

[0061] The foamable composition has non-flammability and low smoke release, and its combustion performance is that it cannot be ignited, and the total smoke release is less than 100m 2 / m 2 , here can not be ignited specifically refers to exposure to 50kW / m 2 The TTI (ignition time) under the radiant heat source is greater than 300 seconds.

[0062] The perfluororubber foam formed by the foamable composition has high temperature resistance and can be used at 300°C or even 320°C.

[0063] The foamed structure formed by the foamable composition is mainly a closed-cell structure, and the possibility of a mixed-cell structure containing a small amount of open cells is not excluded. The cells of the closed-cell foamed rubber are independent and not interconnected, so it has excellent impact resistance, rebound, softness, waterproofness, gas resistance, sound insulation and heat insulation performance, and can be used in liquid floating products, buffer materials, thermal insulation materials, sports equipment, aerospace insulation, thermal insulation materials and other products and fields.

[0064] The pore size can be nanometer or micrometer. According to the specific application requirements and application occasions, different formula combinations are formed mainly by adjusting the type and amount of foaming promoter, as well as the amount of fumed silica, to prepare low-smoke, non-flammable perfluororubber foams with different pore structures and contents.

[0065] The second aspect of the present invention provides a method for preparing the low-smoke, non-flammable perfluororubber foam composition described in the first aspect of the present invention. The method for preparing the perfluororubber foam composition comprises: uniformly mixing perfluororubber, nano-β-silicon nitride and fumed silica under heating conditions, and then gradually adding a foaming promoter multiple times in an open mill to obtain a low-smoke, non-flammable perfluororubber foam composition. The multiple additions are multiple slow additions.

[0066] In some specific embodiments, the components such as perfluororubber, nano-β-silicon nitride, fumed silica or other reinforcing materials are fully mixed and stirred under heating conditions using a torque rheometer, and then a predetermined number of foaming promoters are added in small amounts multiple times on a two-roll mill to obtain a sheet of perfluororubber foam composition.

[0067] The third aspect of the present invention provides a foam, the preparation method of which comprises subjecting the low-smoke, non-flammable perfluororubber foam composition of the first aspect of the present invention to a primary vulcanization molding using a flat vulcanizing agent, followed by a secondary vulcanization molding under heating conditions, to finally obtain a perfluororubber foam with a certain foaming rate.

[0068] In the present invention, the foaming process is preferably completed during the primary vulcanization and / or secondary vulcanization process, and a foamed body of a certain shape can be obtained at the end of the secondary vulcanization. The perfluororubber foamed body with a preliminary shape (e.g., sheet or block) after foaming and cross-linking can also be further cut to obtain a foamed body of a specific size and size, and used as the final product.

[0069] There is no particular limitation on the molding method of the foamed body made from the perfluororubber foam formulation, and various molding methods can be cited, such as press molding (compression molding), extrusion molding, injection molding, etc. Preferably, the molding is performed by sulfur molding under the condition of simultaneous heating and pressurization.

[0070] Specifically, the preparation method includes: preparing a foamed body by one-step or multi-step foaming of the aforementioned low-smoke, non-flammable perfluororubber foam composition, wherein the foaming process includes a primary vulcanization and shaping under heating and pressurization conditions, and then a secondary vulcanization process is used to make the foaming more complete and the shape more stable, thereby finally forming a foamed body of a specific shape.

[0071] The one-step foaming or multi-step foaming molding method specifically refers to a foaming process in which the total foaming rate can be concentrated in one step or completed in multiple foaming steps.

[0072] The foaming process includes the first vulcanization by compression molding or extrusion molding under heating and pressure. The temperature of the first vulcanization can be 150℃~190℃, and can be 150℃~160℃, 160℃~190℃, 150℃~170℃, 170℃~185℃, 185℃~190℃, 160℃~170℃, 170℃~180℃ or 180℃~190℃, etc. The time can be 1min~30min, and can be 1min~5min, 5min~10min, 10min~15min, 15min~20min or 20min~30min, etc. The pressure is 3~10Mpa, and can be 3~10Mpa, 3~5Mpa, 5~8Mpa or 8~10Mpa, etc. During the first vulcanization molding, the mold can be used to make sheets, strips, tubes and other shapes.

[0073] The secondary vulcanization process makes the foaming more complete and finally forms a foamed product of a fixed shape. The temperature of the second vulcanization process can be in the range of 220℃~300℃, and can be selected as 220℃~240℃, 240℃~260℃, 260℃~280℃ or 280℃~300℃, etc. The time is 1hr~48hr, and can be selected as 1hr~48hr, 1hr~8hr, 8hr~16hr, 16hr~24hr, 24hr~36hr or 36hr~48hr, etc.

[0074] The fourth aspect of the present invention provides the use of the perfluororubber foam composition as described in the first aspect of the present invention and / or the foam prepared as described in the third aspect of the present invention in the fields of electronics, electrical, aerospace, semiconductors, machinery, and packaging.

[0075] Specifically, the high temperature resistant perfluororubber foamed products can be used in the fields of high temperature resistance, electrical insulation, heat insulation, cushioning, sound insulation, etc. in electronics, electrical, aerospace, semiconductors, machinery, packaging, etc.

[0076] The beneficial effects of the present invention are further illustrated below in conjunction with embodiments.

[0077] In order to make the invention purpose, technical scheme and beneficial technical effect of the present invention clearer, the present invention is further described in detail below in conjunction with examples. However, it should be understood that the examples of the present invention are only for explaining the present invention, not for limiting the present invention, and the examples of the present invention are not limited to the examples given in the specification. The specific experimental conditions or operating conditions not specified in the examples are made under conventional conditions, or are made under the conditions recommended by the material supplier.

[0078] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0079] In the following examples, the reagents, materials and instruments used are all commercially available unless otherwise specified.

[0080] Perfluoro rubber raw rubber: FFKM1 containing cyanide is model G806HT produced by Zhonghao Chenguang, and its Mooney viscosity ML1+10@121℃ is about 40; FFKM2 containing cyanide is PFE131T produced by 3M, and its Mooney viscosity ML1+10@121℃ is 80;

[0081] β-Silicon nitride (particle size 20-100 nm), manufacturer: Adamas;

[0082] Aerosil R972, fumed silica, BET surface area 110 ± 20 m2 / g, manufacturer is Evonik;

[0083] Aerosil R805, fumed silica, BET surface area 150 ± 25 m 2 / g, manufacturer is Evonik;

[0084] Aerosil RY50, a fumed silica, has a BET surface area of ​​30 ± 15 m 2 / g, manufacturer is Evonik;

[0085] Chemicals such as benzyl carbamate, phthalamide, DBU, 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (BOAP), butyl carbamate, urea and urea derivatives, the manufacturer is Aladdin.

[0086] Other reinforcing fillers: PTFE micropowder, manufactured by Solvay, with an average particle size of 1 to 5 μm; carbon nanotubes, manufactured by Ocsial, etc.

[0087] The test methods or standards involved are as follows

[0088] 1. Specific gravity of the sample after disulfide ρ1: According to ASTM D 1622-08 "Standard Test Method for Density and Specific Gravity (Density)", the test is carried out using a foam density tester. The tester can measure the mass of the sample in the air and the volume of water displaced when the sample is completely immersed in water according to the built-in program, and calculate the ratio of the two to obtain the specific gravity of the foam rubber sample.

[0089] 2. Calculation of foaming rate: (2.1-ρ1)*100% / 2.1, where ρ1 is the specific gravity of perfluororubber foam relative to water, and 2.1 is the commonly used specific gravity of unfoamed perfluororubber vulcanized products. The actual value may deviate slightly, and this difference is ignored here.

[0090] 3. Combustion test: According to GB / T 16172-2016, the test equipment is FTT0007 cone calorimeter of FTT company, and the energy density of thermal radiation source is 50kW / m 2 , sample thickness 5mm, sample area 60cm 2 , the smoke release is the total area of ​​smoke released per unit area, in mm 2 / mm 2 , TTI is the ignition time, in seconds (s).

[0091] Example 1

[0092] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0093] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 8 parts of nano-β-silicon nitride (particle size is 20-100nm), and 20 parts of fumed silica R972 are first added into a mixer, mixed at 80-120°C for 10-20 minutes, and then discharged on an open mill for standby use.

[0094] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, and the foaming is completed in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide is foamed simultaneously, and finally a square or annular foam can be obtained. Finally, the specific gravity, foaming rate, and combustion performance of the ignition time and smoke volume are tested.

[0095] Example 2

[0096] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0097] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 30 parts of nano-β-silicon nitride (particle size is 20-100nm), and 20 parts of fumed silica R972 are first added into a mixer, and mixed at a temperature of 80-120°C for 10-20 minutes, and then 1 part of benzyl carbamate is gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0098] Preparation method of perfluororubber foam: This example adopts a two-step foaming method, and there is a certain degree of foaming in the first sulfur and second sulfur processes. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a first vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first sulfur molding time is about 20 minutes, and the second sulfur is heated at a temperature of 250-300°C for 30 hours. Under this condition, the second sulfur is foamed simultaneously, and finally a square or annular foamed product can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0099] Example 3

[0100] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0101] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 15 parts of nano-β-silicon nitride (particle size is 20-100nm), and 30 parts of fumed silica R972 are first added into a mixing machine, mixed at a temperature of 80-120°C for 10-20 minutes, and then 0.2 parts of phthalamide are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0102] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, and the foaming is mainly completed in the disulfide process. Specific steps: After weighing the sheet composition, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0103] Example 4

[0104] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0105] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 40 parts of nano-β-silicon nitride (particle size is 20-100nm), and 5 parts of fumed silica R972 are first added into a mixing machine, mixed at a temperature of 80-120°C for 10-20 minutes, and then 0.5 parts of phenylaminourea are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0106] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, and the foaming is mainly completed in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foamed product can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0107] Example 5

[0108] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0109] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 15 parts of nano-β-silicon nitride (particle size is 20-100nm), and 15 parts of fumed silica R972 are first added into an internal mixer, and the internal mixing is carried out at a temperature of 80-120°C for 10-20 minutes, and then 0.2 parts of carbon nanotubes and 0.2 parts of DUB are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0110] Preparation method of perfluororubber foam: This example adopts a two-step foaming method, and there is a certain degree of foaming in the first sulfur and second sulfur processes. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a first vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first sulfur molding time is about 20 minutes, and the second vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, the two sulfurs are foamed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0111] Example 6

[0112] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0113] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM2 raw rubber, 30 parts of nano-β-silicon nitride (particle size is 20-100nm), and 10 parts of fumed silica R972 are first added into a mixing machine, and mixed at a temperature of 80-120°C for 10-20 minutes, and then 3 parts of PTFE micropowder are gradually and slowly added on an open mixing mill, and then 0.5 parts of BOAP are slowly added and the mixture is discharged for standby use.

[0114] Preparation method of perfluororubber foam: This example adopts a two-step foaming method, and there is a certain degree of foaming in the first sulfur and second sulfur processes. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a first vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first sulfur molding time is about 20 minutes, and the second vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, the two sulfurs are foamed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0115] Example 7

[0116] A low-smoke, non-flammable perfluororubber foam composition and a method for preparing the foam, comprising the following steps:

[0117] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 20 parts of nano-β-silicon nitride (particle size is 20-100nm), and 10 parts of fumed silica R805 are first added into a mixing machine, mixed at a temperature of 80-120°C for 10-20 minutes, and then 0.5 parts of butyl carbamate are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0118] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, and the foaming is mainly completed in the disulfide process. Specific steps: After weighing the sheet composition, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0119] Comparative Example 1

[0120] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0121] Preparation method of perfluororubber foam composition: 100 parts of FFKM1 raw rubber and 8 parts of nano-β-silicon nitride (particle size of 20-100nm) are first added into a mixer, mixed at 80-120°C for 10-20 minutes, and then discharged on an open mill for standby use.

[0122] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, and the foaming is mainly completed in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0123] Comparative Example 2

[0124] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0125] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber and 30 parts of nano-β-silicon nitride (particle size of 20-100 nm) are first added into a mixer, and mixed at 80-120° C. for 10-20 minutes, and then 5 parts of benzyl carbamate are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0126] Preparation method of perfluororubber foam: This example adopts a two-step foaming method, and there is a certain degree of foaming in the first sulfur and second sulfur processes. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a first vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first sulfur molding time is about 20 minutes, and the second sulfur is heated at a temperature of 250-300°C for 30 hours. Under this condition, the second sulfur is foamed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0127] Comparative Example 3

[0128] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0129] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber and 30 parts of nano-β-silicon nitride (particle size of 20-100nm) are first added into a mixer, and mixed at 80-120°C for 10-20 minutes, and then 1 part of benzyl carbamate is gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0130] Preparation method of perfluororubber foam: This example adopts a two-step foaming method, and there is a certain degree of foaming in the first sulfur and second sulfur processes. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a first vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first sulfur molding time is about 20 minutes, and the second sulfur is heated at a temperature of 250-300°C for 30 hours. Under this condition, the second sulfur is foamed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0131] Comparative Example 4

[0132] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0133] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber and 15 parts of nano-β-silicon nitride (particle size is 20-100nm) are first added into a mixing machine, mixed at 80-120°C for 10-20 minutes, and then 0.2 parts of phthalamide are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0134] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, mainly forming a certain degree of foaming in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0135] Comparative Example 5

[0136] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0137] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 20 parts of nano-β-silicon nitride (particle size is 20-100nm) and 15 parts of fumed silica Aerosil RY 50 are first added into a mixer, mixed at 80-120°C for 10-20 minutes, and then discharged on an open mill for standby use.

[0138] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, mainly forming a certain degree of foaming in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0139] Comparative Example 6

[0140] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0141] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM2 raw rubber and 40 parts of nano-β-silicon nitride (particle size is 20-100nm) are first added into an internal mixer, and the internal mixing is carried out at a temperature of 80-120°C for 10-20 minutes, and then 0.5 parts of phenylaminourea are gradually and slowly added on an open mill, and then sheets are produced for standby use.

[0142] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, mainly forming a certain degree of foaming in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0143] Comparative Example 7

[0144] The preparation method of the perfluororubber composition and the foamed body thereof comprises the following steps:

[0145] The preparation method of the perfluororubber foam composition is as follows: 100 parts of FFKM1 raw rubber, 30 parts of nano-β-silicon nitride (particle size is 20-100nm) and 21 parts of fumed silica Aerosil R972 are first added into a mixer, mixed at 80-120°C for 10-20 minutes, and then discharged on an open mill for standby use.

[0146] Preparation method of perfluororubber foam: This example adopts a one-step foaming method, mainly forming a certain degree of foaming in the disulfide process. Specific steps: After weighing the composition of the sheet, place it in a square or annular mold cavity, and then perform a vulcanization molding under heating and pressurization conditions, wherein the heating temperature is set to 150-190°C, the pressure is 3-10MPa, the first vulcanization molding time is about 20 minutes, and the secondary vulcanization is heated at a temperature of 250-300°C for 30 hours. Under this condition, disulfide foaming is performed simultaneously, and finally a square or annular foam can be obtained, and finally the specific gravity, foaming rate and combustion performance are tested.

[0147] The test results of each embodiment and comparative example are shown in Table 1.

[0148] Table 1

[0149]

[0150] Combined with Table 1, it can be seen from Example 1 and Comparative Example 1, Example 2 and Comparative Example 3, Example 3 and Comparative Example 4, Examples 4 to 7, and Comparative Example 6 that the addition of fumed silica is beneficial to increasing the foaming rate of the perfluororubber foam and at the same time can reduce the total smoke release of the foam.

[0151] From Comparative Example 2, it can be seen that although the composition with more foaming promoter added can obtain a foam with a higher foaming rate, the total smoke release of the foam is higher, greater than 100m 2 / m 2 .

[0152] From Comparative Example 5, it can be seen that the addition of fumed silica with a smaller BET surface area does not contribute significantly to improving the foaming rate of the perfluororubber foam, but has a beneficial effect on reducing the smoke release.

[0153] It can be seen from Comparative Example 7 that when the addition amount of nano-β-silicon nitride and fumed silica is too large, greater than 50 parts, the composition has a problem of yield rate during molding and other processing, and the defects on the surface of the product will affect the foaming rate, so it is not conducive to obtaining a foam with a high foaming rate.

[0154] In summary, the present invention effectively overcomes the shortcomings of some formula combinations in the prior art, such as low foaming ratio or large smoke release during combustion, and has high industrial utilization value.

[0155] The above is only a preferred embodiment of the present invention, and is not any formal or substantial limitation of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and supplements without departing from the method of the present invention, and these improvements and supplements should also be regarded as the protection scope of the present invention. Any technician familiar with this profession, without departing from the spirit and scope of the present invention, can make some changes, modifications and evolutions of the technical content disclosed above, which are equivalent embodiments of the present invention; at the same time, any changes, modifications and evolutions of any equivalent changes made to the above embodiments based on the essential technology of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A low-smoke, non-flammable perfluororubber foam composition, characterized in that: The low-smoke, non-flammable perfluororubber foam composition is composed of the following raw materials in parts by weight: 100 parts of perfluoro rubber; 8-40 parts of nano-β-silicon nitride; 5-30 parts of fumed silica; 0.2 to 1.8 parts of foaming accelerator; The total weight of nano-β-silicon nitride and fumed silica is not more than 50 parts; The perfluororubber contains cyano groups, which are located at the end of the main chain or at the side chain; the cyano groups are introduced by copolymerizing a crosslinking point monomer containing cyano groups with tetrafluoroethylene, perfluoroalkyl vinyl ether or perfluoroalkoxy vinyl ether to form a copolymer; The foaming promoter is an amine compound; the amine compound is selected from one or more of phenyl semicarbazide, 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (BOAP), 1,8-diazabicycloundec-7-ene (DBU), carbamate compounds and phthalamide; The foamed body formed by the perfluororubber foamed body composition has a foaming ratio higher than 50%.

2. The low-smoke, non-flammable perfluororubber foam composition according to claim 1, characterized in that: The Mooney viscosity ML (1+10) @ 121°C of the cyano group-containing perfluoro rubber is 20-95.

3. The low-smoke, non-flammable perfluororubber foam composition according to claim 2, characterized in that: The Mooney viscosity ML (1+10) @ 121°C of the cyano group-containing perfluoro rubber is 30-80.

4. The low-smoke, non-flammable perfluororubber foam composition according to claim 1, characterized in that: Also includes any one or more of the following features: B1) the particle size of the nano-β-silicon nitride is less than 500 nm; B2) the weight proportion of the nano-β-silicon nitride is 10 to 30 parts; B3) the weight proportion of the fumed silica is 8 to 15 parts; B4) The BET surface area of ​​the fumed silica is ≥50 m 2 / g; B5) the total amount of the nano-β-silicon nitride and fumed silica added is not more than 45 parts; B7) the foamable composition further comprises other reinforcing fillers or high temperature resistant pigments; B8) the cell structure of the foamable composition is mainly a closed cell structure; B9) the foaming rate of the foamable composition is greater than 50% and less than 98%; B10) The foamable composition has non-flammability and low smoke release, and the non-flammability is 50kW / m 2 TTI under radiant heat source>300 seconds, total smoke release <100m 2 / m 2 .

5. The low-smoke, non-flammable perfluororubber foam composition according to claim 4, characterized in that: Also includes any one or more of the following features: B11) In feature B1), the particle size of the nano-β-silicon nitride is 20nm to 500nm; B21) In feature B2), the weight proportion of the nano-β-silicon nitride is 10 to 25 parts; B41) In feature B4), the BET surface area of ​​the fumed silica is ≥ 80 m 2 / g; B71) In feature B7), the other reinforcing fillers include inorganic fillers and / or organic reinforcing fillers; B72) In feature B7), the weight proportion of the other reinforcing fillers is 0 to 30 parts.

6. The low-smoke, non-flammable perfluororubber foam composition according to claim 5, characterized in that: Also includes any one or more of the following features: B111) In feature B1), the particle size of the nano-β-silicon nitride is 20 to 100 nm; B711) In feature B71), the other reinforcing fillers are selected from PTFE micropowder and / or carbon nanotubes; B712) In feature B71), the inorganic filler is selected from one or more of carbon black, carbon fiber, carbon nanotube, alumina, nitride, carbide, silicate, and barium sulfate; the organic reinforcing material is selected from one or more of polyamide, polyimide, polyphenylene sulfide, polyether sulfone, polyetherimide, polyether ether ketone, and polytetrafluoroethylene powder; B721) In feature B72), the weight proportion of other reinforcing fillers is 0 to 5 parts.

7. The low-smoke, non-flammable perfluororubber foam composition according to claim 1, characterized in that: The carbamate compound is selected from one or more of benzyl carbamate, butyl carbamate, tert-butyl carbamate, N-(benzyloxy)amino tert-butyl ester, methyl-tert-butyl carbamate, and benzyl tert-butyl carbamate.

8. The method for preparing the low-smoke, non-flammable perfluororubber foam composition according to any one of claims 1 to 7, characterized in that: The preparation method comprises: uniformly mixing perfluororubber, nano-β-silicon nitride and fumed silica under heating conditions, and then gradually adding a foaming promoter multiple times in an open mill to obtain a low-smoke-releasing, non-flammable perfluororubber foam composition.

9. A foam, characterized in that: The low-smoke, non-flammable perfluororubber foam composition as described in claim 8 is prepared into a foam by one-step foaming or multiple-step foaming, wherein the foaming process of the low-smoke, non-flammable perfluororubber foam composition includes a primary vulcanization and shaping process and a secondary vulcanization process under heating and pressure to finally form a foam of a fixed shape.

10. Use of the low-smoke, non-flammable perfluororubber foam composition according to any one of claims 1 to 7 and / or the foam according to claim 9 in the fields of electronics, electrical engineering, aerospace, semiconductors, machinery, and packaging.

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