Low-density flame-retardant organic silicon foam composition, silicon rubber foam material and preparation method of low-density flame-retardant organic silicon foam composition and silicon rubber foam material

Abstract

The invention discloses a low-density flame-retardant organic silicon foam composition, a silicon rubber foam material and a preparation method of the low-density flame-retardant organic silicon foam composition and the silicon rubber foam material, and the foam composition comprises the following components in parts by weight: (A) 100 parts of organopolysiloxane; (B) 5-100 parts of a reinforcing filler; (C) 20-100 parts of a composite flame-retardant filler; (D) 1-10 parts of a structuring control agent; (E) 1-10 parts of a foaming agent; (F) 1-10 parts of an auxiliary foaming agent; (G) 1-10 parts of hydrogen-containing siloxane; (H) 0.01-3 parts of a platinum group metal compound catalyst; (I) 0.01-1 part of an inhibitor; according to the organic silicon foam composition, the component (F) and the component (E) are introduced, so that the foaming speed and the curing speed can be better matched, the organic silicon foam composition has a relatively high foaming ratio after being cured, the density of a material can be remarkably reduced, and meanwhile, foam pores of foam are uniform and fine in size.

Description

Technical Field

[0001] The invention relates to the field of organosilicon polymer materials, and in particular to a low-density flame-retardant organosilicon foam composition, a silicone rubber foam material and a preparation method thereof. Background Art

[0002] In the past, rail transit seat backs, car interiors, etc. generally use high polymer materials such as polystyrene and polyurethane to achieve the purpose of weight reduction and noise reduction. Although this type of foam material has the advantages of simple manufacturing process, highly controllable density, and wide application range, its molecular structure determines that this type of foam material is highly toxic, especially during the combustion process, it will produce a large amount of toxic gases, which will pose a serious threat to human life safety. In particular, some foreign countries have banned the use of polyurethane foam materials in rail transit.

[0003] Low-density flame-retardant silicone foam material has the advantages of both silicone rubber material and foam material. It is a new type of high-value-added composite material with low density and controllable hardness. It has the characteristics of silicone rubber material such as high and low temperature resistance, weather resistance, corrosion resistance, and flame retardancy, and at the same time has the properties of foam material such as low specific gravity, heat insulation, and sound insulation. At present, the market share of silicone foam materials in the market is basically occupied by American companies such as Rogers, Dow Corning, and Wacker.

[0004] Under the premise of controlling the viscosity of the system and the later foaming temperature, it is impossible to make the foamed board have the characteristics of low specific gravity and meet the UL94-V0. The density of the foamed board is determined by two aspects, one is the density of the rubber body, and the other is the foaming ratio of the rubber. The existing foaming agent has an upper limit, that is, after adding a certain amount, the foaming ratio of the board does not increase but decreases. Secondly, a simple flame retardant filler needs to be added in a sufficient amount to ensure the flame retardant performance of the material UL94-V0. Therefore, the superposition of these two reasons directly limits the foamed board from meeting the low density and having the flame retardant performance of UL94-V0.

[0005] Chinese invention patent CN105602258 B discloses a low-density foamed silicone rubber composition and a silicone rubber sponge. On the basis of the existing disclosed formula of silicon-hydrogen foamed silicone rubber composition, a certain amount of non-ionic surfactant is added, especially additional water-containing powder and non-ionic surfactant are added in combination, which can greatly improve the foaming performance of the composition, and obtain a higher foaming rate than the conventional composition formula, a lower product density, and better cell uniformity.

[0006] However, the foaming silicone rubber composition does not solve the flame retardancy problem, and the simple use of non-ionic surfactants cannot make the foaming aids exist stably in the system, and it is easy to lose its original function after being stored in the rubber material for a period of time.

[0007] Chinese patent invention CN109456600A provides a method for preparing foamed silicone rubber with excellent flame retardant properties, but this method is only applicable to the preparation of medium and high density foamed silicone rubber and cannot be used to prepare low density foamed silicone rubber materials.

[0008] Chinese invention patent application CN106589956 A provides a low-density flame-retardant silicone rubber foam material and a preparation method thereof, which is prepared from the following raw materials by mass: 100 parts of silicone rubber raw rubber, 10-40 parts of reinforcing agent, 3-9 parts of anti-structuring agent, 3-10 parts of foaming agent, 2-8 parts of foaming agent, 2-5 parts of vulcanizing agent, 10-50 parts of inorganic flame retardant, 10-50 parts of organic flame retardant, and through a certain processing technology, a silicone rubber foam material with low density, uniform pore structure and excellent flame retardant performance is prepared. A physical foaming method is adopted to prepare a foamed board with lower density and good flame retardancy by adding nitroso compounds, azo compounds or carbonate compounds and modified urea.

[0009] However, this method has strict control over the molecular weight of methyl vinyl silica gel, which is between 400,000 and 700,000. At the same time, a higher temperature is required in the later foaming process. The molecular weight and high temperature will greatly limit its use in the actual production process because of the high requirements for equipment and operation. This patent is mainly used in the production of high-temperature solid foam glue, which is physical foaming. The purpose of foaming is achieved by combining nitroso compounds, azo compounds or carbonate compounds with modified urea to decompose and produce gas at high temperature.

[0010] Therefore, there is an urgent need to provide a low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof that can obtain a silicone foam material by heating and foaming and curing at medium temperature to solve the above-mentioned problems. Summary of the invention

[0011] In order to overcome the problems existing in the prior art, the present invention aims to provide a silicone rubber foam material formed by curing a low-density flame-retardant silicone foam composition, wherein the density of the produced silicone foam material is ≤210kg / m 3 The foam cells are uniform and fine, the mechanical properties are excellent, the compression deformation performance is good, and it meets UL94V-0. It can be widely used in new energy vehicles, urban rail transit, weight reduction, noise reduction, shock absorption, flame retardancy, battery heat insulation protection and other aspects.

[0012] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows: A low-density flame-retardant silicone foam composition comprises the following components in parts by weight: (A) 100 parts of organopolysiloxane; (B) 5 to 100 parts of reinforcing filler; (C) 20 to 100 parts of composite flame retardant filler; (D) 1 to 10 parts of a structuring control agent; (E) 1 to 10 parts of a foaming agent; (F) 1 to 10 parts of a foaming agent; (G) 1 to 10 parts of hydrogen-containing siloxane; (H) 0.01 to 3 parts of a platinum group metal compound catalyst; (I) 0.01 to 1 part of inhibitor. The component (A) organopolysiloxane contains at least two alkenyl groups in each molecule, and its terminal alkenyl group can be one or more of vinyl, allyl, pentenyl or hexenyl. In order to better realize the present invention, vinyl is particularly preferred. In addition to the terminal alkenyl group in component (A), the organic group of the siloxane side chain can also include alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, etc.; aryl groups, such as phenyl, tolyl, etc.; alkenyl groups, such as vinyl, allyl, pentenyl, hexenyl, etc. In order to better realize the present invention, methyl is particularly preferred. The organopolysiloxane with a molecular weight of 10,000 to 100,000 and a vinyl content of 0.05 to 0.20% is preferred.

[0013] The component (B) is a reinforcing filler capable of enhancing the mechanical properties of the organic silicon foam material. The reinforcing filler of the component (B) is one or more of fumed silica, precipitated silica, methyl MQ silicone resin and vinyl MQ silicone resin.

[0014] The component (C) composite flame retardant filler is a compound of two or more materials selected from aluminum hydroxide, magnesium hydroxide, zinc borate, zinc oxide, mica powder, carbon black, graphite powder, montmorillonite, glass powder, antimony trioxide and iron oxide. The flame retardant compounded in a certain proportion is added to the rubber compound, and the main chain of silicone rubber -Si-O-Si will be transformed into a continuous, insulating network-like SiO2 at high temperature. The flux melts to form a flowing liquid that fills between the flame retardant filler and SiO2, playing the role of a connecting "bridge". After cooling, a dense ceramic layer is formed to prevent further combustion of the foam material, achieving a V0 flame retardant effect.

[0015] The component (D) structure control agent is a small molecular polysiloxane compound containing hydroxyl groups, which can control the viscosity growth of the rubber to a certain extent as a structure control agent, and prolong the use time of the rubber. The component (D) structure control agent is trimethylsilanol, dimethylsilanediol, diphenyldisilanol or hydroxy silicone oil, and the hydroxy silicone oil has a hydroxyl content of 3% to 10% and a viscosity of 10 to 100 cs.

[0016] The foaming agent as component (E) mainly reacts with the hydrogen-containing siloxane as component (G) to generate gas to form foam. The foaming agent of component (E) is a monohydric alcohol having 1 to 12 carbon atoms, a polyhydric alcohol having 1 to 12 carbon atoms or a hydroxy silicone oil. When it is a monohydric alcohol, an aliphatic alcohol or an aromatic alcohol having 1 to 12 carbon atoms is selected, such as methanol, ethanol, isopropanol, butanol, isobutanol, benzyl alcohol, phenylethyl alcohol, etc., preferably benzyl alcohol. When component (E) is a polyhydric alcohol, a dihydric aliphatic alcohol or an aromatic alcohol having 1 to 12 carbon atoms is selected, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, glycerol, pentaerythritol, etc., preferably ethylene glycol, 1,3-propylene glycol, 1,4-butylene glycol. When component (E) is a hydroxy silicone oil, trimethylsilanol, dimethylsilanediol or a small molecule hydroxy silicone oil can be selected, preferably a hydroxy silicone oil having a hydroxyl content of 5% to 10%.

[0017] The component (F) is an organosilicon-modified polymer, and the general structural formula is shown in Formula 1: Wherein, R1 represents vinyl, allyl, butene, pentene or ethynyl, R2 is methyl, ethyl, propyl, epoxy, cyclopentyl, phenyl, benzyl or phenethyl, and groups of these groups substituted by halogen atoms or cyano groups, R3 represents a group that is the same as or different from R2, and is methyl, phenyl or amino; m and n represent the number of chain segments of different groups in the organosilicon-modified polymer, wherein m and n are 1 to 10; The modified polysiloxane with octyl as the side chain of the organosilicon-modified polymer of component (F) can make it more stable in the organosilicon system, and will not affect its good foaming synergy with the foaming agent in the system over time. At the same time, the unsaturated groups on the main chain can participate in the curing reaction, further balancing the speed of addition and dehydrogenation reactions during the foaming process. And if the side chain group of the organosilicon-modified polymer of component (F) is a short-chain alkane with less than 8 carbon atoms such as methyl, propyl, and pentyl, it cannot effectively carry out a synergistic foaming reaction with the foaming agent in the system; if the side chain group has more than 8 carbon atoms, its long chain is easy to reduce the activity and cannot better match the foaming and curing speeds during the reaction, thereby affecting the foaming ratio and cell fineness of the board.

[0018] The general structural formula of the hydrogen-containing siloxane of the component (G) is one or more structures in Formula 2: Wherein, R1 and R2 are methyl, ethyl, propyl, epoxy, cyclopentyl, phenyl, benzyl, phenethyl or hydrogen; Methyl and hydrogen groups are particularly preferred; m and n represent the number of chain segments of different groups in the organosilicon-modified polymer, wherein m and n are 1 to 10; On average, each molecule contains at least two or more hydrogen atoms connected to silicon atoms.

[0019] The branched structure as described in Formula 2 in the hydrogen-containing siloxane of the component (G) can react with the hydroxyl group in the component (E) to generate gas on the one hand, and can react with the vinyl group in the system to solidify the silicone foam material on the other hand. Therefore, the branched structure can give the hydrogen-containing polysiloxane better foaming and cross-linking activity, and promote the relative matching of the foaming speed and the curing speed during the reaction process.

[0020] The viscosity (25°C) of the hydrogen-containing siloxane of the component (G) is 1 to 100 cs, and the hydrogen-containing siloxane has a hydrogen content of 1% to 1.67%. The types of hydrogen-containing siloxane can be selected and used alone or in combination.

[0021] The platinum group metal catalyst of component (H) is chloroplatinic acid, triphenylphosphine platinum, olefinic complexes of platinum, carbonyl platinum chelates or alkynyl siloxane platinum chelates, and platinum compounds soluble in polysiloxane, such as olefinic complexes of platinum, are particularly preferred.

[0022] The platinum olefin complex catalyst is shown in the general structural formula 3: The structural form of the platinum olefin complex as shown in Formula 3 can more effectively ensure the catalytic activity of the core platinum and prevent it from being oxidized.

[0023] Platinum group metal catalysts can not only promote the silylation reaction between hydrogen atoms and vinyl groups, but also promote the dehydrogenation reaction between silylation and cross-linking agents, foaming agents, and auxiliary foaming agents to produce hydrogen foaming.

[0024] The amount of platinum group metal catalyst added is 0.01 to 3 parts, preferably 1 part. When the amount added is too little, the reaction is too slow and difficult to solidify, and the dehydrogenation to produce hydrogen foaming effect is not ideal; when the amount added is too much, it is easy to cause the operation time to be too short and the cost to increase. When the platinum olefin complex is used as a catalyst, it can not only promote the silane addition reaction between hydrogen atoms and vinyl groups, but also promote the dehydrogenation reaction between silane and crosslinking agents, foaming agents, and auxiliary foaming agents to produce hydrogen foaming.

[0025] The inhibitor of component I is polyvinyl polysiloxane with a vinyl content of 10% to 20%, tetramethyl divinyl siloxane, methyl butynol, cyclohexynol, maleic acid ester, etc. Polyvinyl siloxane, methyl butynol, and cyclohexynol are preferred.

[0026] Another object of the present invention is to provide a silicone rubber foam material formed by curing a low-density flame-retardant organic silicone foam composition under the premise of low density.

[0027] A method for preparing a silicone rubber foam material formed by curing a low-density flame-retardant silicone foam composition, wherein the specific curing method is: 1) Component (A), component (B), component (C) and component (D) are heated and kneaded in a kneader with a vacuum degree of 0.1 MPa for 6 hours, and then cooled to room temperature; 2) grinding and dispersing the kneaded material in step 1) by a three-roll mill and a stirrer, and then adding component (E), component (G), component (F) and component (I) to mix evenly; 3) When curing is required, add component (H) to the material mixed evenly in step 2) and mix evenly, and cure in an oven at 50-90°C for 15-25 minutes to form; 4) The material obtained by curing in step 3) is placed in an oven at 90-110° C. for 10-20 minutes for second-stage curing to obtain a low-density flame-retardant silicone foam material.

[0028] Beneficial effects of the present invention: 1. The silicone foam composition of the present invention introduces component (F) and component (E) to better match the foaming speed and the curing speed, so that it has a higher foaming ratio after curing, can significantly reduce the density of the material, and at the same time make the pore size of the foam uniform and fine.

[0029] 2. After the organic silicone foam composition of the present invention is cured, the main chain -Si-O-Si- structure of the composite flame retardant filler will gradually transform into a continuous, insulating network-like SiO2 during the combustion process. The added flux forms a flowing liquid after melting, which fills the flame retardant filler and the network-like SiO2 and acts as a connecting "bridge". After cooling, a dense ceramic layer is formed to prevent further combustion of the foam material, so that the material has a flame retardant grade of UL94 V0.

[0030] 3. In the present invention, by adding component (F) silicone modified polymer material, the introduction of side chain octyl group can make it better mixed with the silicone component in the system, so that the dispersion uniformity and stability of the foaming agent in the component can be significantly improved, and by controlling the ratio of the side chain octyl group to the foaming agent, the synergistic effect of the two can be better exerted to significantly improve the foaming ratio; at the same time, the unsaturated groups on the main chain can also participate in the reaction to match the foaming speed and the curing speed, so that a higher foaming rate, a lower product specific gravity and a finer pore size are obtained than conventional foaming materials; and if the side chain group of the silicone modified polymer of component (F) is a short-chain alkane with less than 8 carbon atoms such as methyl, propyl, and pentyl, it cannot effectively carry out a synergistic foaming reaction with the foaming agent in the system; if the side chain group has more than 8 carbon atoms, its long chain is easy to reduce the activity and cannot better match the foaming and curing speeds during the reaction, thereby affecting the foaming ratio and pore fineness of the board.

[0031] 4. In the present invention, by adding the component (G) hydrogen-containing siloxane as shown in Formula 2, the branched structure can give the hydrogen-containing polysiloxane better foaming and cross-linking activity, and promote the foaming speed and curing speed to be relatively matched during the reaction process.

[0032] 5. In the present invention, a platinum group metal catalyst of component (H) as shown in Formula 3 is used. The structural form of this complex can more effectively ensure the catalytic activity of the core platinum and prevent it from being oxidized. When the olefinic complex of platinum is used as a catalyst, it can not only promote the silylation reaction between hydrogen atoms and vinyl groups, but also promote the dehydrogenation reaction between silylation and cross-linking agents, foaming agents, and auxiliary foaming agents to produce hydrogen foaming. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a picture of the cell morphology test of the silicone rubber foam material in Example 1 of the present invention; Figure 2 This is a picture of the cell morphology test of the silicone rubber foam material in Example 2 of the present invention; Figure 3 This is a picture of the cell morphology test of the silicone rubber foam material in Example 3 of the present invention; Figure 4 This is a picture of the cell morphology test of the silicone rubber foam material in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] The present disclosure, including the relevant parameters or data in the embodiments, was obtained by the following test methods: 1. Density test method of silicone rubber foam material formed after curing of silicone foam composition: Based on GB / T533-2008 Method for Determining Density of Vulcanized Rubber or Thermoplastic Rubber, the sample is a cylinder with a diameter of 30 mm and a height of 2 mm.

[0036] 2. Test method for flame retardant properties of silicone rubber foam material formed after curing of silicone foam composition: Based on GB / T2408-2008 test method for flame retardant of vulcanized rubber, the sample is a rectangular parallelepiped with a length of 125mm, a width of 13mm and a thickness not exceeding 13mm.

[0037] 3. Testing method for the cell morphology of silicone foam: Cut the sample into thin slices, observe and take pictures under a 50x digital microscope.

[0038] Example 1 A low-density flame-retardant silicone foam composition, which comprises, by mass, 100 parts of organopolysiloxane (A), 20 parts of reinforcing filler (B), 50 parts of composite flame-retardant filler (C), 5 parts of structuring control agent (D), 5 parts of foaming agent (E), 5 parts of auxiliary foaming agent (F), 4 parts of hydrogen-containing siloxane (G), 1 part of catalyst (H), and 0.03 parts of inhibitor (I).

[0039] The component (A) is an organopolysiloxane having a terminal olefin group of vinyl, a side chain group of methyl, a molecular weight of 60,000, and a vinyl content of 0.1%; The component (B) is fumed silica; The component (C) is a compound having a mass ratio of aluminum hydroxide:magnesium hydroxide:zinc borate:glass powder=2:1:1:1; The component (D) is a hydroxy silicone oil having a hydroxy content of 5% and a viscosity of 15 cs; The component (E) is benzyl alcohol; The component (F) is an organosilicon-modified polysiloxane, and the general structural formula is shown in Formula 1: Wherein, R1 is vinyl, R2 is methyl, R3 is vinyl, m = 5, n = 5; The component (G) is hydrogen-containing siloxane, the general structural formula of which is shown in Formula 2, and the hydrogen-containing silicone oil has a hydrogen content of 1.5% and a viscosity (25°C) of 15 cs; Wherein R1 is a methyl group, R2 is a hydrogen group, wherein m=7, n=10; The component (H) is a vinyl silicone oil solution of tetramethyldivinyldisiloxane platinum complex having a platinum content of 5000 ppm as shown in the general structural formula 3; Formula 3 The component (I) is a polyvinylsiloxane with a vinyl content of 20%; The method for curing the low-density flame-retardant silicone foam composition to form a silicone rubber foam material is as follows: 1) Component (A), component (B), component (C) and component (D) are heated and kneaded in a kneader with a vacuum degree of 0.1 MPa for 6 hours, and then cooled to room temperature; 2) grinding and dispersing the kneaded material in step 1) by a three-roll mill and a stirrer, and then adding component (E), component (G), component (F) and component (I) to mix evenly; 3) When curing is required, add component (H) to the material mixed evenly in step 2) and mix evenly, and cure in an oven at 70°C for 20 minutes; 4) The material obtained by curing in step 3) is placed in an oven at 100° C. for 15 minutes for second-stage curing to obtain a low-density flame-retardant silicone foam material.

[0040] The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 158 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=2s; like Figure 1 Shown is a picture of the cell morphology test of the silicone rubber foam material in Example 1.

[0041] Example 2 A low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof, compared with Example 1, the difference is: The foam composition, in parts by mass, comprises 100 parts of (A), 100 parts of reinforcing filler (B), 100 parts of composite flame retardant filler (C), 10 parts of structural control agent (D), 10 parts of foaming agent (E), 10 parts of auxiliary foaming agent (F), 10 parts of hydrogen-containing siloxane (G), 3 parts of catalyst (H), and 1 part of inhibitor (I); wherein the component (A) is an organic polysiloxane having a terminal olefin group of pentenyl, a side chain group of vinyl, a molecular weight of 10,000, and a vinyl content of 0.05%; The component (B) is precipitated silica; The component (C) is a composite material with a mass ratio of graphite powder to montmorillonite of 2:1; The component (D) is a hydroxy silicone oil having a hydroxy content of 3% and a viscosity of 10 cs; The component (E) is ethylene glycol; The component (F) is an organosilicon-modified polysiloxane, and the general structural formula is shown in Formula 1: Wherein, R1 is pentenyl, R2 and R3 are phenyl, m=1, n=3; The component (G) is hydrogen-containing siloxane, the general structural formula of which is shown in Formula 2, and the hydrogen-containing silicone oil has a hydrogen content of 1% and a viscosity (25°C) of 1 cs; Wherein R1 and R2 are methyl groups, wherein m=10, n=1; The component (H): chloroplatinic acid; The component (I) is a polyvinylsiloxane with a vinyl content of 10%; The method for curing the low-density flame-retardant silicone foam composition to form a silicone rubber foam material is as follows: 1) Component (A), component (B), component (C) and component (D) are heated and kneaded in a kneader with a vacuum degree of 0.1 MPa for 6 hours, and then cooled to room temperature; 2) grinding and dispersing the kneaded material in step 1) by a three-roll mill and a stirrer, and then adding component (E), component (G), component (F) and component (I) to mix evenly; 3) When curing is required, add component (H) to the material mixed evenly in step 2) and mix evenly, and cure in an oven at 50°C for 25 minutes; 4) The material obtained by curing in step 3) is placed in an oven at 110° C. for 10 minutes for second-stage curing to obtain a low-density flame-retardant silicone foam material.

[0042] like Figure 2 Shown is a picture of the cell morphology test of the silicone rubber foam material of Example 2; The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 183 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=3s.

[0043] Example 3 A low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof, compared with Example 1, the difference is: The foam composition, in parts by mass, comprises 100 parts of (A), 5 parts of reinforcing filler (B), 20 parts of composite flame retardant filler (C), 1 part of structural control agent (D), 1 part of foaming agent (E), 1 part of auxiliary foaming agent (F), 1 part of hydrogen-containing siloxane (G), 0.01 part of catalyst (H), and 0.01 part of inhibitor (I); The component (A) is an organopolysiloxane having a hexenyl terminal group, a phenyl side chain group, a molecular weight of 100,000, and a vinyl content of 0.2%; The component (B) is methyl MQ silicone resin; The component (C) is a compound with a mass ratio of zinc oxide: mica powder: carbon black: antimony trioxide: iron oxide = 1:1:2:1:1; The component (D) is a hydroxy silicone oil having a hydroxy content of 10% and a viscosity of 100 cs; The component (E) is hydroxy silicone oil with a hydroxyl content of 8%; The component (F) is an organosilicon-modified polysiloxane, and the general structural formula is shown in Formula 1: Wherein, R1 is ethynyl, R2 is monochloromethyl, R3 is amino, m=4, n=10; The component (G) is hydrogen-containing siloxane, the general structural formula of which is shown in Formula 2, and the hydrogen-containing silicone oil has a hydrogen content of 1.67% and a viscosity (25°C) of 100 cs; Wherein R1 is a hydrogen group, R2 is a phenyl group, wherein m=1, n=6; The component (H) is a platinum chelate of carbonyl; The component (I) is methylbutynol; The method for curing the low-density flame-retardant silicone foam composition to form a silicone rubber foam material is as follows: 1) Component (A), component (B), component (C) and component (D) are heated and kneaded in a kneader with a vacuum degree of 0.1 MPa for 6 hours, and then cooled to room temperature; 2) grinding and dispersing the kneaded material in step 1) by a three-roll mill and a stirrer, and then adding component (E), component (G), component (F) and component (I) to mix evenly; 3) When curing is required, add component (H) to the material mixed evenly in step 2) and mix evenly, and cure in an oven at 90°C for 15 minutes; 4) The material obtained by curing in step 3) is placed in an oven at 90° C. for 20 minutes for second-stage curing to obtain a low-density flame-retardant silicone foam material.

[0044] like Figure 3 Shown is a picture of the cell morphology test of the silicone rubber foam material in Example 3; The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 178 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=5s.

[0045] Example 4 Compared with Example 1, this embodiment is different in that: The auxiliary foaming agent of component (F) is organosilicon-modified polysiloxane, and the general structural formula is shown in Formula 1: Wherein, R1 is ethynyl, R2 is methyl, R3 is amino, m=10, n=7; The remaining components are the same as those in Example 1. In this example, a silicone rubber foam material is prepared in the same manner as in Example 1.

[0046] The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 196 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=4s.

[0047] Example 5 Compared with Example 1, this embodiment is different in that: The auxiliary foaming agent of component (F) is organosilicon-modified polysiloxane, and the general structural formula is shown in Formula 1: Wherein, R1 is butenyl, R2 is chlorophenethyl, R3 is amino, m=8, n=4; The remaining components are the same as those in Example 1.

[0048] In this example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0049] The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 188 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=2s.

[0050] Example 6 Compared with Example 1, this embodiment is different in that: The terminal alkenyl groups of the organopolysiloxane of component (A) include vinyl and acrylic groups, and the side chain groups include methyl and vinyl groups.

[0051] The reinforcing filler of component (B) is fumed silica:precipitated white carbon black=1:1, and the other components are the same as those in Example 1.

[0052] In this example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0053] The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 205 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=3s.

[0054] Example 7 Compared with Example 1, this embodiment is different in that: The component (D) structuring control agent is diphenyl disilanol, and the other components are the same as those in Example 1.

[0055] In this example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0056] The density of the low-density flame-retardant silicone foam material obtained in this embodiment is 185 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=2s.

[0057] Comparative Example 1 A low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof. Compared with Example 1, the difference lies in that component (F) in the silicone foam composition is deleted, and the remaining components are the same as those in Example 1.

[0058] In this comparative example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0059] like Figure 4 Shown is a picture of the cell morphology test of the silicone rubber foam material of Comparative Example 1; The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 355 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=4s.

[0060] Comparative Example 2 A low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof. Compared with Example 1, the difference is that the component (G) hydrogen-containing siloxane is a hydrogen-containing siloxane with a hydrogen content of 0.05% and a viscosity of 5 cs, and the other components are the same as those in Example 1.

[0061] In this comparative example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0062] The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 278 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=6s.

[0063] Comparative Example 3 A low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof, compared with Example 1, the difference is that: the component (E) foaming agent is water, and the other components are the same as those in Example 1.

[0064] The other components of the foam composition in this comparative example are the same as those in Example 1; In this comparative example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0065] The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 323 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=3s.

[0066] Comparative Example 4 A low-density flame-retardant organic silicone foam composition, a silicone rubber foam material and a preparation method thereof, compared with Example 1, the difference is that: the flame-retardant filler of component (C) is magnesium hydroxide, and the other components are the same as those in Example 1.

[0067] In this comparative example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0068] The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 198 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=15s.

[0069] Comparative Example 5 A low-density flame-retardant silicone foam composition, a silicone rubber foam material and a preparation method thereof, compared with Example 1, the difference is: In this comparative example, the method for curing the low-density flame-retardant organic silicone foam composition to form a silicone rubber foam material is as follows: 1) Component (A), component (B), component (C) and component (D) are heated and kneaded in a kneader with a vacuum degree of 0.1 MPa for 1 hour, and then cooled to room temperature; 2) grinding and dispersing the kneaded material in step 1) by a three-roll mill and a stirrer, and then adding component (E), component (G), component (F) and component (I) to mix evenly; 3) When curing is required, the material mixed evenly in step 2) is added with component (H) and mixed evenly, and cured in an oven at 50° C. for 25 minutes to obtain a low-density flame-retardant silicone foam composition.

[0070] The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 286 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=3s.

[0071] Comparative Example 6 A low-density flame-retardant organic silicon foam composition and a silicone rubber foam material formed by curing thereof, compared with Example 1, the difference is: The octyl group in the side chain of the foaming aid organosilicon-modified polysiloxane component (F) as described in Example 1 was replaced with a butyl group, and the remaining components were the same as those in Example 1.

[0072] In this comparative example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0073] The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 335 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=2s.

[0074] Comparative Example 7 A low-density flame-retardant silicone foam composition and a silicone rubber foam material formed by curing thereof. Compared with Example 1, the difference lies in that the octyl group of the side chain of the foaming aid silicone-modified polysiloxane component (F) as described in Example 1 is replaced by a dodecyl group, and the remaining components are the same as those in Example 1.

[0075] In this comparative example, a silicone rubber foam material was prepared in the same manner as in Example 1.

[0076] The density of the low-density flame-retardant silicone foam material obtained in this comparative example is 305 kg / m 3 , UL94V-0 fire self-extinguishing time t1+t2=3s.

[0077] The test results of density, flame retardancy and cell morphology of Examples 1-7 are shown in Table 1; the test results of density, flame retardancy and cell morphology of Comparative Examples 1-7 are shown in Table 2.

[0078] Table 1 Density, flame retardancy and cell morphology test results of Examples 1-7 Table 2 Density, flame retardancy and cell morphology test results of Comparative Examples 1-7 From Table 1, Table 2 and Figure 1-4 It can be seen that: In Comparative Example 1, after deleting the component (F) silicone-modified polymer, the density of the silicone rubber foam material increased significantly, and the cell morphology changed significantly, the cells became significantly coarser, and the size was uneven; In Comparative Examples 6 and 7, when the side chain group of the organosilicon-modified polymer of component (F) is a butyl group with less than 8 carbon atoms, it cannot effectively carry out a synergistic foaming reaction with the foaming agent in the system, and the density of the organosilicon foam material is relatively large, and the pores are relatively large and uneven in size; when the side chain group is a dodecyl group with more than 8 carbon atoms, its long chain easily reduces the activity and cannot better match the foaming and curing speeds during the reaction, thereby affecting the foaming ratio and pore fineness of the organosilicon foam material. The density of the organosilicon foam material is relatively large, and the pores are relatively coarse and uneven in size; when the group on the side chain of component F is an octyl group, the pore structure of the foam material is more delicate and uniform.

[0079] In Comparative Example 2, the hydrogen atoms on the side chain or end chain of component (G) can react with the hydroxyl group in component G to produce gas, and can also react with the vinyl group in the system to solidify the silicone foam material. Therefore, when the hydrogen content in component (G) decreases, the density of the silicone rubber foam material increases significantly, and the pores are coarse and uneven in size.

[0080] In Comparative Example 3, the foaming agent of component (E) can match the foaming speed and curing speed with component (F), so that it has a higher foaming ratio after curing, which can significantly reduce the density of the material and make the pore size of the foam uniform and fine. Therefore, when component (E) is replaced with water, it cannot cooperate with component (F), resulting in poor foaming effect of the silicone rubber foam material, high density, coarse pores and uneven size.

[0081] In Comparative Example 4, a flame retardant compounded in a certain proportion is added to the rubber material. At high temperature, the main chain of silicone rubber -Si-O-Si will be transformed into a continuous, insulating network-like SiO2, and the flux melts to form a flowing liquid that fills between the flame retardant filler and SiO2, playing the role of a connecting "bridge". After cooling, a dense ceramic layer is formed to prevent further combustion of the foam material, achieving a V0 flame retardant effect. The flame retardant effect of Comparative Example 4 with the addition of a non-compounded flame retardant is significantly lower than that of the embodiment with the addition of a compounded flame retardant.

[0082] The embodiments described above are only for better illustrating the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made based on the above contents of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-density flame-retardant silicone foam composition, characterized in that: The following components are included by weight: (A) 100 parts of organopolysiloxane; (B) 5 to 100 parts of reinforcing filler; (C) 20 to 100 parts of composite flame retardant filler; (D) 1 to 10 parts of a structuring control agent; (E) 1 to 10 parts of a foaming agent; (F) 1 to 10 parts of a foaming agent; (G) 1 to 10 parts of hydrogen-containing siloxane; (H) 0.01 to 3 parts of a platinum group metal compound catalyst; (I) 0.01 to 1 part of inhibitor; The organopolysiloxane of component (A) contains at least two alkenyl groups in each molecule, wherein the terminal alkenyl groups are one or more of vinyl, allyl, pentenyl and hexenyl, and the side chain organic groups are one or more of alkyl, alkenyl and aryl; The component (D) structuring control agent is a hydroxyl-containing small molecule polysiloxane compound; The foaming agent of component (E) is a monohydric alcohol having 1 to 12 carbon atoms, a polyhydric alcohol having 1 to 12 carbon atoms or a hydroxy silicone oil, and the hydroxy content of the hydroxy silicone oil is 5% to 10%; The auxiliary foaming agent of component (F) is an organosilicon modified polymer, and its general structural formula is shown in Formula 1: Wherein, R1 represents vinyl, allyl, butene, pentene or ethynyl, R2 is methyl, ethyl, propyl, epoxy, cyclopentyl, phenyl, benzyl or phenethyl, and groups of these groups substituted by halogen atoms or cyano groups, R3 represents a group that is the same as or different from R2, and is methyl, phenyl or amino; Wherein, m and n are 1 to 10; The component (G) hydrogen-containing siloxane has a viscosity of 1 to 100 cs at 25°C and a hydrogen content of 1% to 1.67%; The platinum group metal catalyst of component (H) is chloroplatinic acid, triphenylphosphine platinum, an olefin complex of platinum, a carbonyl platinum chelate or an alkynyl siloxane platinum chelate.

2. The organosilicon foam composition according to claim 1, characterized in that: The general structural formula of the component (G) containing hydrogen siloxane is shown in Formula 2: Wherein, R1 and R2 are methyl, ethyl, propyl, epoxy, cyclopentyl, phenyl, benzyl, phenethyl or hydrogen; m and n are 1 to 10.

3. The organosilicon foam composition according to claim 1, characterized in that: The platinum group metal catalyst of component (H) is an olefinic complex of platinum, and its general structural formula is shown in Formula 3: 。 4. The organosilicon foam composition according to claim 1, characterized in that: The molecular weight of the organopolysiloxane of component (A) is 10,000 to 100,000, and the vinyl content of the organopolysiloxane of component (A) is 0.05 to 0.20%.

5. The organosilicon foam composition according to claim 1, characterized in that: The reinforcing filler of component (B) is one or more of fumed silica, precipitated silica, methyl MQ silicone resin and vinyl MQ silicone resin.

6. The organosilicon foam composition according to claim 1, characterized in that: The component (C) composite flame retardant filler is a compound of two or more of aluminum hydroxide, magnesium hydroxide, zinc borate, zinc oxide, mica powder, carbon black, graphite powder, montmorillonite, glass powder, antimony trioxide and iron oxide.

7. The organosilicon foam composition according to claim 1, characterized in that: The component (D) structure control agent hydroxyl-containing small molecule polysiloxane compound is trimethylsilanol, dimethylsilanediol, diphenyldisilanol or hydroxy silicone oil. The hydroxyl content of the hydroxy silicone oil is 3% to 10% and the viscosity is 10 to 100 cs.

8. The organosilicon foam composition according to claim 1, characterized in that: The inhibitor of component (I) is one or more of polyvinyl polysiloxane with a vinyl content of 10% to 20%, methyl butynol and cyclohexynol.

9. A silicone rubber foam material, characterized in that: The silicone rubber foam material is obtained by curing the organic silicone foam composition according to any one of claims 1 to 8.

10. A method for preparing a silicone rubber foam material from the silicone foam composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: 1) Component (A), component (B), component (C) and component (D) are heated and kneaded in a kneader with a vacuum degree of 0.1 MPa for 6 hours, and then cooled to room temperature; 2) grinding and dispersing the kneaded material in step 1) by a three-roll mill and a stirrer, and then adding component (E), component (G), component (F) and component (I) to mix evenly; 3) When curing is required, add component (H) to the material mixed evenly in step 2) and mix evenly, and cure in an oven at 50-90°C for 15-25 minutes to form; 4) The material obtained by curing in step 3) is placed in an oven at 90-110° C. for 10-20 minutes for second-stage curing to obtain a low-density flame-retardant silicone foam material.

Images