阅读说明：本技术 一种电子产品用有机硅发泡片材及其制备方法 (Organic silicon foamed sheet for electronic products and preparation method thereof ) 是由 方凯 魏琼 于 2021-07-08 设计创作，主要内容包括：本发明属于防水减震密封材料领域,更具体地,涉及一种电子产品用有机硅发泡片材及其制备方法。该有机硅发泡片材厚度为50um～2000um,其具有闭孔结构,闭孔率为92％以上；所述有机硅发泡片材的平均泡孔直径为16～40um,所述有机硅发泡片材中的全部泡孔的90％以上的泡孔直径在70um以下。本发明提供的有机硅发泡片材,其可表现出优异的减震性能,可在-40℃～180℃的宽广温度区域中表现出稳定的损耗因子tanδ,且在该温域中均具有较低的压缩永久变形；同时,本发明提供的有机硅发泡片材,具有优异的防水密封性能和阻燃性能,非常适用于电子产品的防水减震密封。(The invention belongs to the field of waterproof and damping sealing materials, and particularly relates to an organic silicon foamed sheet for electronic products and a preparation method thereof. The thickness of the organic silicon foaming sheet is 50-2000 um, the organic silicon foaming sheet has a closed cell structure, and the closed cell rate is more than 92%; the average diameter of the foam holes of the organic silicon foamed sheet is 16-40 um, and more than 90% of the diameter of the foam holes of all the foam holes in the organic silicon foamed sheet is below 70 um. The organosilicon foaming sheet provided by the invention can show excellent shock absorption performance, can show a stable loss factor tan delta in a wide temperature range of-40-180 ℃, and has lower compression permanent deformation in the temperature range; meanwhile, the organic silicon foamed sheet provided by the invention has excellent waterproof sealing performance and flame retardant property, and is very suitable for waterproof damping sealing of electronic products.)

1. An organic silicon foaming sheet is characterized in that the thickness of the organic silicon foaming sheet is 50-2000 um; the organosilicon foaming sheet has a closed cell structure, and the closed cell rate of the organosilicon foaming sheet is more than 92%; the average cell diameter of the organic silicon foamed sheet is 16-40 um; more than 90% of all cells in the silicone foamed sheet have a cell diameter of 70um or less.

2. The silicone foamed sheet according to claim 1, wherein the silicone foamed sheet has a tan δ value in the range of-40 ℃ to 180 ℃ at 30HZ that is 90% to 150% of the tan δ value of the silicone foamed sheet at 30HZ and 25 ℃.

3. The silicone foamed sheet of claim 1, wherein the silicone foamed sheet has a compression set of less than 10% at-40 ℃/50% compression/22 h and at 180 ℃/50% compression/22 h.

4. The silicone foamed sheet according to claim 1, wherein the silicone foamed sheet has a flame retardant property of up to UL94V 1.

5. The silicone foamed sheet according to claim 1, wherein the silicone foamed sheet is formed by heat curing of a silicone resin composition.

6. The silicone foamed sheet according to claim 5, wherein the silicone resin composition comprises at least:

(A)100 parts by mass of a terminal vinyl polysiloxane having a functionality of 2;

(B) the mass ratio of the polyvinyl polysiloxane with the functionality degree of more than or equal to 2 to the component (A) is 0.02-0.15: 1;

(C) polysiloxane with functionality more than or equal to 2 and containing hydrosil on side chain, wherein the ratio of the mole number of the hydrogen atoms combined with silicon atoms in the component (C) to the total mole number of vinyl in the components (A) and (B) is 1.2-10: 1;

(D) 3-7 parts by mass of fumed silica;

(E) 0.5-2 parts by mass of deionized water;

(F) 1-4 parts by mass of expanded microspheres, wherein the particle size of the expanded microspheres is 8-12 um;

(G) 2-5 parts by mass of an inorganic flame retardant with a particle size of 5-10 um;

(H)0.5 to 1 part by mass of a hydrosilylation addition reaction catalyst;

(I)0.01 to 0.1 part by mass of an inhibitor for delaying hydrosilylation.

7. The silicone foamed sheet according to claim 6, wherein the ratio of the amount of the substance of vinyl groups to the amount of the substance of silicone segments in component (A) is 0.15% to 0.35%; the ratio of the amount of vinyl substances to the amount of silicone chain substances in the component (B) is 1-22%; the content of hydrosilation in the component (C) is 0.18-1.6%.

8. The method for producing the silicone foamed sheet according to any one of claims 1 to 7, comprising the steps of: coating the organic silicon resin composition on the lower film A, and covering the upper surface of the organic silicon resin composition with the upper film B; then, the silicone resin composition covered with the upper and lower films is subjected to heat curing; and removing the upper and lower films, and then performing post-curing to obtain the organic silicon foamed sheet.

9. The production method according to claim 8, wherein the silicone resin composition is obtained by the steps of:

(1) mixing the total amount of the component (B), the component (D) and the component (H) with half of the amount of the component (A) to obtain a first composition A;

(2) mixing the total amount of the component (C), the component (E), the component (F), the component (G) and the component (I) with the other half of the amount of the component (A) to obtain a second composition B;

(3) and (2) carrying out reduced pressure stirring on the first composition A and the second composition B at the temperature of 30-40 ℃ to obtain the organic silicon resin composition.

10. A waterproof shock-absorbing sealing material for electronic products, comprising the silicone foamed sheet according to any one of claims 1 to 7.

Technical Field

The invention belongs to the field of waterproof and damping sealing materials, and particularly relates to an organic silicon foamed sheet for electronic products and a preparation method thereof.

Background

The existing waterproof shock-absorbing sealing material for consumer electronics is mainly ultrathin IXPE foam, has excellent sealing and waterproof performance and good shock-absorbing performance, but has extremely poor flame retardant property and poor high and low temperature resistance. Along with the requirements on the thickness of equipment, the requirements on the data processing capacity of the equipment are higher and lower, the power of the equipment is higher and higher, the heat generation is higher and higher, and further the requirements on the flame retardant property and the high temperature resistance of the waterproof shock-absorbing sealing material for the interior of the equipment are higher and higher.

Compared with the C-C molecular chain structure of IXPE foam, the Si-O-Si molecular chain structure of the organic silicon foam enables the organic silicon foam to have natural excellent high and low temperature resistance and flexibility (the Si-O bond energy is 452KJ/mol, the C-C bond energy is 346KJ/mol, the organic silicon has high temperature resistance and ultraviolet aging resistance, the Si-O rotational energy is 0.837KJ/mol, the C-C rotational energy is 13.811KJ/mol, the organic silicon has low temperature resistance, compared with the bond length of 154pm C-C bond and the bond angle of 112 DEG, the bond length of 163pm Si-O bond and the bond angle of 130 DEG, the organic silicon has better flexibility), and can be used for a long time under the extreme high and low temperature conditions of 200 ℃ and-55 ℃, meanwhile, the excellent shock resistance is kept in a wide temperature range of-40 ℃ to 180 ℃; compared with an organic structure of IXPE foam, the semi-organic-semi-inorganic structure of the organic silicon foam enables the organic silicon foam to have excellent flame retardant property. Therefore, in the field of waterproof and damping sealing materials for electronic products, the organic silicon foam has the great performance advantage of replacing IXPE foam.

At present, the organic silicon foam is mainly applied to the rail transit and new energy battery industries, the thickness is basically 2mm or more, and the ultrathin foaming sheet suitable for electronic products cannot be prepared by the formula, matched equipment and a preparation process. How to design the formula of organosilicon foaming sheet, select suitable manufacture equipment and the preparation technology of matching for the organosilicon foaming sheet that prepares has excellent waterproof shock attenuation sealing performance when having ultra-thin thickness, can also compromise excellent fire-retardant and high temperature resistance to satisfy the application demand of electronic product, is the technical problem that awaits solution at present.

Disclosure of Invention

Aiming at the performance defects of the existing ultrathin IXPE foam used as a waterproof shock-absorbing sealing material for consumer electronics and the urgent requirements on high temperature resistance, flame retardance and shock absorption of the waterproof shock-absorbing sealing material brought by the development trend of electronic products, the invention aims to provide the organic silicon foamed sheet for the electronic products, which can show excellent high temperature resistance, can be normally used for a long time even when the environmental temperature reaches 180 ℃, shows stable loss factor tan delta and excellent flame retardance, and is very suitable for waterproof shock-absorbing sealing of the electronic products. Another object of the present invention is to provide a method for preparing such a silicone foamed sheet.

According to one embodiment of the invention, the thickness of the silicone foamed sheet is 50-2000 um, wherein the silicone foam sheet has a closed-cell structure, the closed-cell rate is more than 92%, the average cell diameter of the silicone foam sheet is 16-40 um, and the cell diameter of more than 90% of all cells in the silicone foam sheet is less than 70 um.

In one embodiment, the silicone foamed sheet has a tan delta value in the range of-40 ℃ to 180 ℃ at 30HZ that falls between 90% and 150% relative to the tan delta value at 25 ℃/30HZ of the silicone foamed sheet.

In one embodiment, the silicone foamed sheet has a compression set of less than 10% at-40 ℃/50% compression/22 h and 180 ℃/50% compression/22 h.

In one embodiment, the flame retardant performance of the silicone foamed sheet can reach UL94V 1.

In one embodiment, the silicone foamed sheet is formed by thermal curing of a silicone resin composition.

In one embodiment, the silicone resin composition comprises at least: (A)100 parts by mass of a vinyl-terminated polysiloxane having a functionality (functional group vinyl bonded to Si atom) of 2; (B) the mass ratio of the polyvinyl polysiloxane with the functionality (the functional group vinyl is bonded on the Si atom) being more than or equal to 2 to the component (A) is 0.02-0.15: 1; (C) polysiloxane with functionality (the functional group is a hydrogen atom bonded on a Si atom) of more than or equal to 2 and containing hydrosil on a side chain, wherein the ratio of the mole number of the hydrogen atom bonded with the silicon atom in the component (C) to the total mole number of vinyl in the components (A) and (B) is 1.2-10: 1; (D) 3-7 parts by mass of fumed silica; (E) 0.5-2 parts by mass of deionized water; (F) 1-4 parts by mass of expanded microspheres, wherein the particle size of the expanded microspheres is 8-12 um; (G) 2-5 parts by mass of an inorganic flame retardant with a particle size of 5-10 um; (H)0.5 to 1 part by mass of a hydrosilylation addition reaction catalyst; (I)0.01 to 0.1 part by mass of an inhibitor for delaying hydrosilylation.

According to another aspect of the present invention, there is provided a method of preparing a silicone foamed sheet, the method comprising: coating the organic silicon resin composition on an automatic coating machine; the organic silicon resin composition is coated on the lower film A, and the upper surface of the organic silicon resin composition is covered by the upper film B; then, the silicone resin composition covered with the upper and lower films is subjected to heat curing; and removing the upper and lower films, and then performing post-curing to obtain the organic silicon foamed sheet.

In a preferred embodiment, the obtaining of the silicone resin composition comprises the steps of:

(1) mixing the total amount of the component (B), the component (D) and the component (H) with half of the amount of the component (A) to obtain a first composition A;

(2) mixing the total amount of the component (C), the component (E), the component (F), the component (G) and the component (I) with the other half of the amount of the component (A) to obtain a second composition B;

(3) and (2) carrying out reduced pressure stirring on the first composition A and the second composition B at the temperature of 30-40 ℃ to obtain the organic silicon resin composition.

According to the present invention, there is provided a silicone foamed sheet which can exhibit excellent vibration-damping properties, can exhibit a stable loss factor tan δ in a wide temperature region of-40 ℃ to 180 ℃, and has a low compression set in the temperature region; meanwhile, the organic silicon foamed sheet provided by the invention has excellent waterproof sealing performance and flame retardant property, and is very suitable for waterproof damping sealing of electronic products.

Compared with the existing ultrathin IXPE foam of the waterproof and damping sealing material for consumer electronics products, the organic silicon foamed sheet has excellent flame retardant property and high temperature resistance; compared with the existing organic silicon foamed sheet, the organic silicon foamed sheet is thicker and can only be applied to the rail transit and new energy battery industries, the organic silicon foamed sheet is thinner, has excellent waterproof, damping and sealing performances, also has excellent flame retardance and high temperature resistance, and can meet the application requirements of consumer electronics products.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The thickness of the organic silicon foaming sheet is 50-2000 um. Considering the fact that the thickness of the organosilicon foaming sheet prepared based on the prior art (the existing mainstream formula system, manufacturing equipment and corresponding matched preparation process in the organosilicon foaming material industry) is basically 2mm or more, the organosilicon foaming sheet is mainly applied to rail transit and new energy industries and is not suitable for the consumer electronics industry; the value of the silicone foamed sheet of the invention is: the sheet can be used for the purpose that the organosilicon foaming material prepared based on the prior art cannot be suitable. In particular, the silicone foamed sheet of the present invention can meet the following application needs: the thickness of consumer electronics products is thinner and thinner, the requirement on the data processing capacity of equipment is higher and higher, the power of the equipment is higher and higher, the heat generation is higher and higher, and the requirements on the flame retardant property and the high temperature resistance of the waterproof shock-absorbing sealing material for the interior of the equipment are higher and higher. Based on this, the thickness of the silicone foamed sheet of the present invention is preferably 100-. The silicone foamed sheet of the present invention can maintain the expression of the other effects of the present invention even when the thickness is increased as described above.

The silicone foamed sheet of the present invention has cells (spherical bubbles). The cells (spherical bubbles) may not be spherical bubbles in a strict sense, and may be, for example, approximately spherical bubbles having deformation locally or bubbles formed of a space having large deformation. The silicone foamed sheet of the present invention has a closed cell structure. Namely, the silicone foamed sheet of the present invention has a closed cell structure having no through-holes between adjacent cells. When the silicone foamed sheet of the present invention has a closed cell structure, by combining this feature with any other feature of the silicone foamed sheet of the present invention, the sheet can exhibit excellent waterproof, shock-absorbing, sealing, and high-temperature resistance properties, and the performance of these effects can be maintained even when the thickness is reduced.

The closed cell ratio of the silicone foamed sheet of the present invention is 92% or more, preferably 93%, more preferably 95%, still more preferably 97%, even more preferably 99%, and most preferably substantially 100%. When the closed cell ratio of the silicone foamed sheet of the invention falls within the above range, by combining this feature with any other feature of the silicone foamed sheet of the invention, the sheet can exhibit excellent waterproof cushioning as well as high temperature resistance, and the expression of these effects can be maintained even when the thickness is reduced.

The average cell diameter of the organic silicon foamed sheet is 16-40 um. When the average cell diameter of the silicone foamed sheet of the present invention falls within the above range, by combining this feature with any other feature of the silicone foamed sheet of the present invention, the sheet can exhibit excellent waterproof cushioning as well as high temperature resistance, and the expression of these effects can be maintained even when the thickness is reduced.

The silicone foamed sheet of the present invention has 90% or more of all cells having a cell diameter of 70um or less. In the silicone foamed sheet of the present invention, it is preferable that 92% or more of all the cells have a cell diameter of 70um or less, more preferably 95% or more of all the cells have a cell diameter of 70um or less, still more preferably 97% or more of all the cells have a cell diameter of 70um or less, even more preferably 99% or more of all the cells have a cell diameter of 70um or less, and most preferably substantially 100% of all the cells have a cell diameter of 70um or less. In addition, in the silicone foamed sheet of the present invention, it is preferable that 90% or more of all the cells have a cell diameter of 65um or less, more preferably 90% or more of all the cells have a cell diameter of 60um or less, still more preferably 90% or more of all the cells have a cell diameter of 55um or less, even more preferably 90% or more of all the cells have a cell diameter of 50um or less, and most preferably 90% or more of all the cells have a cell diameter of 45um or less. When the ratio of cells each having a cell diameter of 70um or less and the cell diameter each of 90% or more of all the cells therein fall within the above range, the silicone foamed sheet of the present invention can exhibit excellent waterproof cushioning and high-temperature resistance by combining this feature with any other feature of the silicone foamed sheet of the present invention, and the expression of these effects can be maintained even when the thickness is reduced.

The organosilicon foaming sheet has a closed cell structure and fine cell diameters, so that the organosilicon foaming sheet has good damping performance, can show a stable loss factor tan delta in a wide temperature area of-40-180 ℃, and has lower compression permanent deformation in the temperature area; meanwhile, the organic silicon foamed sheet provided by the invention has excellent waterproof sealing performance and flame retardant property, and is very suitable for waterproof damping sealing of electronic products.

The foamed sheet of the present invention can achieve these excellent properties, basically because the formulation of the silicone resin composition used therein determines the pore structure of the resulting silicone foamed sheet, and ultimately determines the properties of the resulting silicone foamed sheet. The closed pore structure and the closed pore rate of the organic foaming sheet determine the waterproof sealing performance of the organic silicon foaming sheet; the size and uniformity of the foam holes, the number of the foam holes and the main molecular structure of the foam sheet (which is embodied on the organosilicon foam sheet and is the toughness, resilience and other properties of the foam hole wall) determine the damping performance, the compression permanent deformation performance and the loss factor tan delta of the organosilicon foam sheet.

The tan delta value of the silicone foamed sheet of the present invention at 30HZ in the range of-40 ℃ to 180 ℃ falls between 90% and 150% of the tan delta value at 25 ℃/30HZ with respect to the silicone foamed sheet, preferably between 100% and 150% of the tan delta value at 25 ℃/30HZ with respect to the silicone foamed sheet, more preferably between 120% and 150% of the tan delta value at 25 ℃/30HZ with respect to the silicone foamed sheet.

The compression set of the silicone foamed sheet of the present invention at-40 ℃/50% compression/22 h and 180 ℃/50% compression/22 h is less than 10%, preferably less than 7%, more preferably less than 4%, and most preferably less than 1%. The physical meaning and the test method of compression set at 40 ℃/50% compression/22 h and 180 ℃/50% compression/22 h are described in the section "compression set test" of the description.

The flame retardant property of the organic silicon foaming sheet can reach UL94V1 (the thickness is more than or equal to 150 um).

The silicone foamed sheet of the present invention is preferably formed by heat curing of the silicone resin composition.

The silicone resin composition is preferably such as described below.

The silicone resin composition comprises at least: (A)100 parts by mass of a vinyl-terminated polysiloxane having a functionality (functional group vinyl bonded to Si atom) of 2; (B) the mass ratio of the polyvinyl polysiloxane with the functionality (the functional group vinyl is bonded on the Si atom) being more than or equal to 2 to the component (A) is 0.02-0.15: 1; (C) a polysiloxane with functionality (the functional group is a hydrogen atom bonded on a Si atom) of more than or equal to 2 and containing hydrosil on a side chain, wherein the ratio of the mole number of the hydrogen atom bonded with the silicon atom in the component (C) to the total mole number of vinyl in the components (A) and (B) is 1.2-10: 1; (D) 3-7 parts by mass of fumed silica; (E) 0.5-2 parts by mass of deionized water; (F) 1-4 parts by mass of expanded microspheres, wherein the particle size of the expanded microspheres is 8-12 um; (G) 2-5 parts by mass of an inorganic flame retardant with a particle size of 5-10 um; (H)0.5 to 1 part by mass of a hydrosilylation addition reaction catalyst; (I)0.01 to 0.1 part by mass of an inhibitor for delaying hydrosilylation.

Component (a) is a vinyl-terminated polysiloxane having a functionality (functional group vinyl bonded to Si atom) of 2, and is a commercially available product. The molar ratio of vinyl groups (the ratio of the amount of vinyl groups to the amount of siloxane units) in component (A) according to the present invention is 0.15% to 0.35%, preferably 0.16% to 0.32%.

Component (B) is a polyvinyl polysiloxane having a functionality (functional group vinyl bonded to Si atom) of 2 or more, and is a commercially available product. The component (B) of the invention has a vinyl group molar ratio of 1-22%, preferably 1-10%, and most preferably 1-5%. The mass ratio of the component (B) to the component (A) is 2 to 15 percent, preferably 11 to 15 percent.

The component (C) is a polysiloxane containing hydrosil on the side chain, the functionality (the functional group is a hydrogen atom bonded on the Si atom) of which is more than or equal to 2, and is a commercial product. The content of hydrosilyl in the component (C) is 0.18-1.6%, and more preferably 1.0-1.6%. The ratio of the number of moles of hydrogen atoms bonded to silicon atoms in component (C) to the total number of moles of vinyl groups in components (A) and (B) is 1.2 to 10:1, preferably 1.2 to 2: 1.

The component (D) fumed silica is a commercial product, is used for reinforcing liquid organic silicon rubber, and is selected from fumed silica subjected to surface treatment such as hexamethyldisilazane, octamethylcyclotetrasiloxane, dimethyldichlorosilane, polydimethylsiloxane and the like. Among them, the effect is better is the gas phase method white carbon black of hexamethyldisilazane surface treatment. Preferably HDK H2000 (manufactured by Wacker Chemical co., ltd.), more preferably R8200 (manufactured by Evonik Degussa co., ltd.).

The expanded microspheres of component (E) are commercially available products selected from domestic products and imported products, preferably Expancel 461DU40(Akzo Nobel Co., Ltd.), more preferably F-48(Japan Matsumoto Oil & Fat Pharmaceutical Co., Ltd.) for foaming of silicone sheets.

The inorganic flame retardant of the component (F) can be one or more of aluminum hydroxide, magnesium hydroxide, low-melting-point glass powder, silicon micropowder, zinc oxide and mica powder.

The catalyst of component (G) is a hydrosilylation reaction catalyst for promoting the hydrosilylation reaction curing of the silicone resin composition, and is selected from a platinum-based catalyst, a palladium-based catalyst, and a rhodium-based catalyst. Among them, the platinum catalyst with better effect comprises: chloroplatinic acid; a complex compound of chloroplatinic acid with an olefin, vinylsiloxane or acetylene compound; alcohol-modified chloroplatinic acid; complexes of platinum with olefins, vinylsiloxanes or acetylene compounds.

The component (H) inhibitor is used for delaying the hydrosilylation reaction speed, improving the processing operation time elasticity during material mixing and proportioning, inhibiting the activity of the catalyst at room temperature, and restoring the catalytic activity of the catalyst when the inhibitor loses effectiveness at high temperature. Selected from alkynol compounds, polyvinyl compounds, N, P, S-containing compounds. Among them, the more effective are alkynyl alcohol compounds, including: 1-ethynyl-1-cyclohexanol, 3, 5-dimethyl-1-hexyn-3-ol, and 3-methyl-1-butyn-3-ol, and the like.

In some embodiments of the present invention, there is also provided a method for preparing the silicone foamed sheet, including the steps of:

(1) mixing the total dosage of the component (B), the component (D) and the component (H) with half of the dosage of the component (A) by using a non-intrusive homogenizer to obtain a first composition A;

(2) mixing the total amount of the component (C), the component (E), the component (F), the component (G) and the component (I) with the other half of the amount of the component (A) by using a non-intrusive homogenizer to obtain a second composition B;

(3) keeping the first composition A and the second composition B in a planetary stirrer at constant temperature (generating heat during stirring, cooling by a mold temperature machine, and keeping the temperature at 30-40 ℃), and stirring under reduced pressure for 5min to obtain the organic silicon resin composition.

The process of the present invention for preparing the mixed component a and the mixed component B separately and then mixing them to obtain the silicone resin composition of the present invention is necessary because: the fumed silica of component (D) has a very small (nanoscale) particle size and is difficult to mix homogeneously into the silicone resin. Through the process of preparing the components A and B respectively and then mixing the components to obtain the organic silicon resin composition, the dispersion of the fumed silica in the organic silicon resin composition is more uniform, and the surface appearance abnormality and the physical property abnormality such as bubble combination, hole breaking, surface protrusion and the like caused by nonuniform distribution can be avoided. Similarly, in the process of preparing the components A and B respectively and then mixing the components to obtain the organic silicon resin composition, a relatively small amount of components such as deionized water, expanded microspheres, inorganic flame retardant, catalyst inhibitor and the like are dispersed in the organic silicon resin composition more uniformly, so that surface appearance abnormity and performance abnormity caused by nonuniform distribution can be avoided.

Coating the obtained organic silicon resin composition on the surface of a lower film A, then covering an upper film B on the upper surface of the resin composition, and then thermally curing the organic silicon resin composition coated with the upper and lower films; and removing the upper and lower films, and then performing post-curing to obtain the organic silicon foamed sheet.

In some embodiments, the resin composition is coated on an automatic coater.

In some embodiments, the upper film B and the lower film a may be a PE film, a PET film, a BOPP film, a composite paper, or the like, and the release agent on the upper film B and the lower film a is a compound that does not react with the silicone resin composition, and may be a fluorine-containing release agent and a non-silicon release agent. The fluorine-containing release agent can be a fluorine-silicon release agent and a fluorine-containing release agent, and the fluorine-silicon release agent can be a fluorine-silicon ring compound; the fluorine-containing release agent may be a homopolymer or copolymer of perfluoroalkyl methacrylate, polyvinyl alcohol perfluorinated urethane, or a fluorine-containing polymer such as a perfluoroalkyl group-containing amino resin. The non-silicon release agent may be a copolymer containing a long-chain alkyl group, a product of mutual reaction of a polar substance and a compound containing a long-chain alkyl group, a complex of a long-chain alkyl carboxylic acid and a chromium salt, a compound having a long-chain alkyl group, and a mixture of various polymers. Preferably, a PET release film or a BOPP film treated by a fluorine-containing release agent is adopted; the heat curing temperature is 80-130 ℃. The primary curing time is 10min to 20min, and the secondary curing, i.e. post-curing time is 5min to 30 min. The lower film B and the upper film A which are made of the materials can be easily peeled off after being heated and cured, and the film material has good heat resistance and is not easy to wrinkle in the heating process.

The following are specific examples:

the vinyl-terminated polysiloxane, polyvinyl polysiloxane, polysiloxane containing hydrosil on side chain, deionized water, inorganic flame retardant, expanded microsphere, catalyst and inhibitor used in the following examples are all commercially available products.

Example 1

50 parts by mass of a terminal vinylpolysiloxane having a vinyl group molar ratio (the ratio of the amount of the substance having a vinyl group to the amount of the substance having a siloxane bond) of 0.16%, 10 parts by mass of a polyvinyl polysiloxane having a vinyl group molar ratio of 5%, and 5 parts by mass of a specific surface area of 160m surface-treated with hexamethyldisilazane²(ii) fumed silica (R8200, a commercially available product) in an amount of 1 part by mass and a Kansted catalyst (platinum metal content: about 5000ppm) in an amount of 1 part by mass were mixed in a non-intrusive homogenizer for 8 minutes to obtain component A;

50 parts by mass of a terminal vinyl polysiloxane having a vinyl group molar ratio (ratio of the amount of a vinyl group-containing substance to the amount of a silicone-linked substance) of 0.16%, 3.30 parts by mass of a side-chain silylhydride-containing polysiloxane having a silylhydride content of 1.6% by weight (the molar number of hydrogen atoms bonded to silicon atoms in the side-chain silylhydride-containing polysiloxane is 6 relative to the molar ratio of vinyl groups in the terminal vinyl polysiloxane and polyvinyl polysiloxane), 1 part by mass of deionized water, 3 parts by mass of expanded microspheres having a particle diameter of 8 μm, and 5 parts by mass of expanded microspheres having a specific surface area of 200 to 450m²Mixing 0.05 part by mass of an inorganic flame retardant (prepared by compounding aluminum hydroxide, magnesium hydroxide, zinc oxide, mica powder and glass powder in a ratio of 7: 20: 4: 30: 10) and 0.05 part by mass of 1-ethynyl cyclohexanol for 8min by using a non-intrusive homogenizer to obtain a component B;

the A, B two-component material is put into a planetary stirrer to be kept at a constant temperature (the stirring process generates heat, the temperature is cooled by a mold temperature machine, the temperature is maintained at 30-40 ℃), and the pressure is reducedStirring for 5min to obtain the silicone resin composition. And coating the organic silicon resin composition on a PET release film treated by the fluorinated organic silicon by using an automatic coating machine, and simultaneously covering the upper surface of the coated organic silicon resin composition by using the PET release film treated by the fluorinated organic silicon. Then heating the silicone resin composition in a forced air drying oven at 90 ℃ for 15min to cure the silicone resin composition; after curing, peeling the upper and lower release films, and continuously heating for 20min in a forced air drying oven at 130 ℃; thereby obtaining a film with a thickness of 150um and a density of 390kg/m³The silicone foamed sheet of (1). The results of various performance tests of the obtained silicone foamed sheet (1) are shown in table 1.

Example 2

50 parts by mass of a terminal vinylpolysiloxane having a vinyl group molar ratio (the ratio of the amount of the substance having a vinyl group to the amount of the substance having a siloxane bond) of 0.32%, 3 parts by mass of a polyvinyl polysiloxane having a vinyl group molar ratio of 22%, and 5 parts by mass of a specific surface area of 300m which had been surface-treated with hexamethylenedisilazane²Mixing fumed silica and 1 part by mass of Kaster catalyst (platinum metal content: about 5000ppm) with a non-intrusive homogenizer for 8min to obtain component A;

50 parts by mass of a terminal vinyl polysiloxane having a vinyl group molar ratio (ratio of the amount of a vinyl group-containing substance to the amount of a silicone-linked substance) of 0.32%, 4.72 parts by mass of a side-chain silylhydride-containing polysiloxane having a silylhydride content of 1.6% by weight (the molar number of hydrogen atoms bonded to silicon atoms in the side-chain silylhydride-containing polysiloxane is 6 relative to the molar ratio of vinyl groups in the terminal vinyl polysiloxane and polyvinyl polysiloxane), 1 part by mass of deionized water, 3 parts by mass of expanded microspheres having a particle diameter of 8 μm, and 5 parts by mass of an expanded microsphere surface-treated with hexamethylenedisilazane and having a specific surface area of 200 to 450m²Mixing 0.05 part by mass of an inorganic flame retardant (prepared by compounding aluminum hydroxide, magnesium hydroxide, zinc oxide, mica powder and glass powder in a ratio of 7: 20: 4: 30: 10) and 0.05 part by mass of 1-ethynyl cyclohexanol for 8min by using a non-intrusive homogenizer to obtain a component B;

stirring A, B two-component materials in a planetStirring in a stirrer at constant temperature (mold temperature machine is used for cooling and stirring to generate heat, and the mold temperature machine is used for cooling, and the temperature is maintained at 30-40 ℃), and stirring under reduced pressure for 5min to obtain the organic silicon resin composition. And coating the organic silicon resin composition on a PET release film treated by the fluorinated organic silicon by using an automatic coating machine, and simultaneously covering the upper surface of the coated organic silicon resin composition by using the PET release film treated by the fluorinated organic silicon. Then heating the silicone resin composition in a forced air drying oven at 90 ℃ for 15min to cure the silicone resin composition; after curing, peeling the upper and lower release films, and continuously heating for 20min in a forced air drying oven at 130 ℃; thereby obtaining a film with a thickness of 150um and a density of 460kg/m³The silicone foamed sheet of (1). The results of various performance tests of the obtained silicone foamed sheet (1) are shown in table 1.

Example 3

50 parts by mass of a terminal vinylpolysiloxane having a vinyl group molar ratio (the ratio of the amount of the substance having a vinyl group to the amount of the substance having a siloxane bond) of 0.16%, 10 parts by mass of a polyvinyl polysiloxane having a vinyl group molar ratio of 5%, and 5 parts by mass of a specific surface area of 300m which had been surface-treated with hexamethylenedisilazane²Mixing fumed silica and 1 part by mass of Kaster catalyst (platinum metal content: about 5000ppm) with a non-intrusive homogenizer for 8min to obtain component A;

50 parts by mass of a terminal vinyl polysiloxane having a vinyl group molar ratio (ratio of the amount of a vinyl group-containing substance to the amount of a siloxane-linked substance) of 0.16%, 5.28 parts by mass of a side-chain silylhydride-containing polysiloxane having a silylhydride content of 1 wt% (the molar number of hydrogen atoms bonded to silicon atoms in the side-chain silylhydride-containing polysiloxane is 6 relative to the molar ratio of vinyl groups in the terminal vinyl polysiloxane and polyvinyl polysiloxane), 1 part by mass of deionized water, 3 parts by mass of expanded microspheres having a particle diameter of 8 μm, and 5 parts by mass of an expanded microsphere surface-treated with hexamethylenedisilazane and having a specific surface area of 200 to 450m²The flame retardant is prepared by compounding inorganic flame retardant (aluminum hydroxide, magnesium hydroxide, zinc oxide, mica powder and glass powder according to the compounding ratio of 7: 20: 4: 30: 10) and 0.05 part by mass of non-intrusive type uniform mixing agent for 1-ethynyl cyclohexanolMixing for 8min to obtain component B;

keeping the A, B two-component material in a planetary stirrer at constant temperature (the mold temperature machine generates heat during cooling and stirring, and the mold temperature machine is used for cooling, and the temperature is maintained at 30-40 ℃), and stirring under reduced pressure for 5min to obtain the organic silicon resin composition. And coating the organic silicon resin composition on a PET release film treated by the fluorinated organic silicon by using an automatic coating machine, and simultaneously covering the upper surface of the coated organic silicon resin composition by using the PET release film treated by the fluorinated organic silicon. Then heating the silicone resin composition in a forced air drying oven at 90 ℃ for 15min to cure the silicone resin composition; after curing, peeling the upper and lower release films, and continuously heating for 20min in a forced air drying oven at 130 ℃; thereby obtaining a film with a thickness of 150um and a density of 365kg/m³The silicone foamed sheet of (1). The results of various performance tests of the obtained silicone foamed sheet (1) are shown in table 1.

Example 4

Example 4 is different from example 1 in that the vinyl group-terminated polysiloxane was used in a vinyl group molar ratio of 0.32%, the polyvinyl polysiloxane was used in a vinyl group molar ratio of 22%, the added part of the polyvinyl polysiloxane was 3 parts by mass, and the pendant silylhydride-containing polysiloxane having a silylhydride content of 1% by weight was added in an amount of 7.55 parts by mass (the molar number of hydrogen atoms bonded to silicon atoms in the pendant silylhydride-containing polysiloxane with respect to the molar ratio of vinyl groups in the terminal vinyl polysiloxane and polyvinyl polysiloxane was 6).

50 parts by mass of a terminal vinylpolysiloxane having a vinyl group molar ratio (the ratio of the amount of the substance having a vinyl group to the amount of the substance having a siloxane bond) of 0.32%, 3 parts by mass of a polyvinyl polysiloxane having a vinyl group molar ratio of 22%, and 5 parts by mass of a specific surface area of 300m which had been surface-treated with hexamethylenedisilazane²Mixing fumed silica and 1 part by mass of Kaster catalyst (platinum metal content: about 5000ppm) with a non-intrusive homogenizer for 8min to obtain component A;

50 parts by mass of a terminal vinyl polysiloxane having a vinyl group molar ratio (the ratio of the amount of a vinyl group-containing substance to the amount of a siloxane-linked substance) of 0.32%, 7.55 parts by mass of a hydrosilyl content of 1wt% of polysiloxane containing silicon and hydrogen in side chain (the molar number of hydrogen atoms bonded with silicon atoms in the polysiloxane containing silicon and hydrogen in side chain is 6 relative to the molar ratio of vinyl in terminal vinyl polysiloxane and polyvinyl polysiloxane), 1 part by mass of deionized water, 3 parts by mass of expanded microspheres with the particle diameter of 8um, and 5 parts by mass of expanded microspheres with the surface treated by hexamethylene disilazane and the specific surface area of 200-450 m²Mixing 0.05 part by mass of an inorganic flame retardant (prepared by compounding aluminum hydroxide, magnesium hydroxide, zinc oxide, mica powder and glass powder in a ratio of 7: 20: 4: 30: 10) and 0.05 part by mass of 1-ethynyl cyclohexanol for 8min by using a non-intrusive homogenizer to obtain a component B;

keeping the A, B two-component material in a planetary stirrer at constant temperature (the mold temperature machine generates heat during cooling and stirring, and the mold temperature machine is used for cooling, and the temperature is maintained at 30-40 ℃), and stirring under reduced pressure for 5min to obtain the organic silicon resin composition. And coating the organic silicon resin composition on a PET release film treated by the fluorinated organic silicon by using an automatic coating machine, and simultaneously covering the upper surface of the coated organic silicon resin composition by using the PET release film treated by the fluorinated organic silicon. Then heating the silicone resin composition in a forced air drying oven at 90 ℃ for 15min to cure the silicone resin composition; after curing, peeling the upper and lower release films, and continuously heating for 20min in a forced air drying oven at 130 ℃; thus, a silicone foamed sheet having a thickness of 150um and a density of 420kg/m3 was obtained. The results of various performance tests of the obtained silicone foamed sheet (1) are shown in table 1.

Comparative example 1

IXPE foam (PO-030015K, manufactured by Hubei Xiangyuan New materials science and technology Co., Ltd.) was sold on the market, had a thickness of 150um and a density of 350kg/m3, and the results of various performance tests are shown in Table 2.

Comparative example 2

A commercially available acrylic foam (ISR ACF-TH, Iwatani co., ltd. manufacture) having a thickness of 150um and a density of 400kg/m3, the results of various performance tests are shown in Table 2.

Comparative example 3

A commercially available polyurethane foam (UFT-20, manufactured by Shanghai high-tech materials, Inc.) having a thickness of 150um and a density of 450kg/m3 was obtained, and the results of various performance tests are shown in Table 2.

Comparative example 4

Commercially available silicone foam (NanNex HT-800, manufactured by Rogers Inoac Corporation) having a thickness of 800um and a density of 320kg/m3, the results of various performance tests are shown in Table 2.

Comparative example 5

The self-made organic silicon foam has the thickness of 600um and the density of 380kg/m 3.

Comparative example 6

The self-made organic silicon foam has the thickness of 400um and the density of 410kg/m 3.

The method of evaluating the properties of the foamed sheets obtained in examples and comparative examples is as follows.

And (3) thickness measurement:

the measurement is carried out by a micrometer, and the test standard is GB/T6342.

Density measurement:

the measurement is carried out by a density balance with the precision of 1mg, and the test standard is GB/T6343-2009.

Observation of cell structure:

the cells in the cross section of the foamed sheet were observed with a scanning electron microscope (S-3400 type scanning electron microscope, magnification 1000 times) to determine whether the cell walls were through.

And (3) measuring the opening rate:

the open cell content of the foamed sheet was measured with an open cell content measuring instrument (HX-TP type) according to GB/T10799-2008. The closed cell fraction was 1-open cell fraction.

Cell diameter measurement:

the cross-sectional cell image of the foamed sheet was observed with a scanning electron microscope (S-3400 type scanning electron microscope, magnification 1000 times), the average diameter of the cells was calculated, and the number of cells was analyzed to be 50.

Loss factor tan δ and its rate of change measurements:

the loss factor tan. delta. at-40 ℃, 25 ℃ and 180 ℃ was measured at a frequency of 30Hz in a tensile measurement mode using a dynamic mechanical analysis tester (Q-800, manufactured by TA Instruments Japan Inc.), and the rate of change was calculated based on the loss factor tan. delta. at 25 ℃.

The rate of change { (loss factor tan. delta. at 180 ℃ C. -loss factor tan. delta. at 25 ℃ C.) + (-loss factor tan. delta. at 40 ℃ C. -loss factor tan. delta. at 25 ℃ C.) }/(loss factor tan. delta. at 25 ℃ C.). times.100%

Impact absorption rate measurement:

the impact absorption rate of the foamed sheet was measured with a home-made impact absorption rate tester. The principle is as follows: and respectively measuring a force value a acquired when 14g of steel ball falls down at a height of 20cm and is hammered onto the force sensor and a force value b acquired when a foamed sheet padded on the force sensor is hammered onto the force sensor, and then calculating the impact absorption rate. Impact absorption rate {1- (b/a) } × 100%.

And (3) testing the flame retardance:

and (3) carrying out flame retardant property test on the foamed sheet by using a vertical combustion box, wherein the test standard is UL 94.

Compression set test:

a sample of 50mm X thickness was laminated to a thickness d0, sandwiched between 2 SUS 304 steel plates, and then the thickness was compressed to the thickness of the spacer and fixed to achieve a 50% compression, followed by leaving the test body to stand in an environment of-40 deg.C, 25 deg.C and 180 deg.C for 22h, respectively. The test body was then released from compression at room temperature and left to stand at room temperature for 24h, the thickness d1 was measured, and the compression set was calculated. The calculation formula is as follows:

compression set { (d 0-d 1)/d0} × 100%

And (3) testing the waterproof performance:

the foamed sheet was subjected to double-sided back-adhesive treatment, and then a window frame-like specimen having a width of 1mm was punched out with a cutter die having an inner frame of 43mm × 33.5mm and an outer frame of 45mm × 35.5 mm. The sample was placed on a polycarbonate plate and spacers were placed on the outside of the sample to achieve 25% compression. The piece which changed color when absorbing water was placed in the middle of the sample, and the polycarbonate plate was covered above the sample. Namely: the sample was clamped between 2 polycarbonate plates and bolted so as to achieve a compression of 25% and a water-absorbing discoloring sheet was placed in the middle of the sample. The resultant was immersed in a water bath at a water depth of 1m for 30 minutes, and the state of immersion inside the sample was evaluated based on the color change of the water-absorbent discoloration sheet.

O: no water immersion

X: immersion occurs

And (3) performance test results:

the foamed sheets obtained in examples and comparative examples were subjected to the above performance tests, and the results are shown in tables 1 and 2, respectively:

table 1 results of performance test of foamed sheets obtained in examples

Table 2 results of property test of foamed sheet obtained in comparative example

As can be seen from comparative example 1 and examples 1 to 4, compared with IXPE foam, the organosilicon foam obtained by the invention has excellent shock absorption and buffering performance, the impact absorption rate (14g steel ball/20 cm height) reaches about 28% (under the same condition, the impact absorption rate of the IXPE foam is 8.5%), the loss factor tan delta (30HZ) reaches more than 0.6 at normal temperature (25 ℃) (the loss factor tan delta of the IXPE foam is 0.21), and the organosilicon foam has very stable loss factor tan delta in a wide temperature range of-40 ℃ to 180 ℃. Compared with IXPE foam, the obtained organic silicon foam has low compression set performance and excellent high temperature resistance, the compression set (50% compression/22 h) at-40 ℃ and 25 ℃ is 0% (the compression set (6.7% and 0.7% respectively) at-40 ℃ and 25 ℃ of the IXPE foam, and the compression set (50% compression/22 h) at 180 ℃ is less than 8% (the compression set (75.3%) at 180 ℃ of the IXPE foam). Meanwhile, the organic silicon foam obtained by the invention has excellent waterproof performance and flame retardant property, and the flame retardant property reaches UL94V1 grade (the flame retardant property of IXPE foam is HB grade).

As can be seen from comparative examples 2 and 3 and examples 1 to 4, compared with the organic silicon foam obtained by the invention, the acrylic foam and the PU foam have relatively low closed-cell rate and relatively large cell diameter, so that the acrylic foam and the PU foam have poor waterproof performance. Compared with the obtained organic silicon foam, the IXPE foam, the acrylic foam and the PU foam have relatively small loss factors tan delta at the temperature of between 40 ℃ below zero and 180 ℃, relatively low impact absorption rate and relatively poor compression set performance and flame retardant performance at the temperature of between 40 ℃ below zero and 180 ℃, and the loss factors tan delta are possibly determined by the molecular structure of the foam sheet main body. Compared with a C-C molecular chain structure, the Si-O-Si molecular chain structure of the organic silicon foam enables the organic silicon foam to have natural excellent high and low temperature resistance and flexibility (the Si-O bond energy is 452KJ/mol, the C-C bond energy is 346KJ/mol, so that the organic silicon has high temperature resistance and ultraviolet aging resistance, the Si-O rotational energy is 0.837KJ/mol, the C-C rotational energy is 13.811KJ/mol, so that the organic silicon has low temperature resistance, and compared with the C-C bond 154pm bond length and 112 degrees bond angle, the Si-O bond 163pm bond length and 130 degrees bond angle, the organic silicon has better flexibility); compared with the organic structures of IXPE foam, acrylic foam and PU foam, the semi-organic-semi-inorganic structure of the organic silicon foam enables the organic silicon foam to have excellent flame retardant property.

It can be seen from comparative examples 1, 2, and 3 that the acrylic foam has superior impact absorption performance compared to IXPE foam and PU foam, the impact absorption rate is 20.2%, which is much higher than 8.5% of IXPE foam and 12.4% of PU foam, which is determined by the main molecular structure of acrylic foam, and the acrylic molecular structure has stronger viscosity. Since the acrylic foam has good impact absorption performance but poor waterproof performance, it cannot be applied to parts requiring both shock absorption and waterproof functions.

It can be known from comparative examples 4 and 6 and examples 1 to 4 that the increase of the diameter of the cells and the decrease of the closed cell rate have negative effects on the loss factor tan δ of the obtained silicone foam and the compression permanent deformation performance at 180 ℃, which is probably because the loss factor tan δ is decreased because the consumption of external stress caused by the compression of the cells is small and the loss factor tan δ is decreased when the foam sheet is deformed by external force after the closed cell rate is decreased (the toughness and strength of the cell wall of the silicone foam prepared by the corresponding formula should also be poor); and after long-time compression at high temperature, the resilience of the foam pores becomes poor and the compression set property becomes poor. Compared with examples 1-4, the waterproof performance of the silicone foam sheet obtained in comparative example 6 is poor, which is probably mainly caused by the increase of the aperture ratio. The increased impact absorption of the silicone foam sheets of comparative examples 4, 5, and 6 compared to examples 1-4 is primarily due to the increased thickness.

As can be seen from comparative example 5 and examples 1 to 4, the average diameter of the cells of the silicone foam obtained in comparative example 5 is relatively large, and the loss factor tan delta is reduced to a certain extent, which is probably because the cell diameter is increased, the cell wall is thickened, and the number of cells in unit volume is reduced, so that when the foam sheet is deformed by external force, the consumption of external stress caused by cell compression is small, and the loss factor tan delta is reduced.

In conclusion, through the technical scheme of the invention, the prepared organic silicon foam sheet has the same thickness and waterproof performance as the ultrathin IXPE foam, has excellent flame retardant performance and high temperature resistance, good damping and buffering performance and lower loss factor compared with the ultrathin IXPE foam, and has stable loss factor tan delta in a wide temperature range of-40-180 ℃. Compared with the common organic silicon foam sheet applied to the rail transit and new energy battery industries in the market at present, the organic silicon foam sheet prepared by the invention has thinner thickness. Therefore, the organic silicon foam sheet prepared by the invention can meet the requirements of electronic products on higher and higher heat resistance and flame retardant property of the waterproof damping sealing material caused by higher and higher power and higher heat generation amount, and is very suitable for the waterproof damping sealing material of consumer electronic products.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.