A silicone rubber and a method for producing the same

Abstract

This invention belongs to the field of silicone rubber technology, specifically relating to a silicone rubber and its preparation method. The silicone rubber is composed of the following components in parts by weight: 90-100 parts methyl vinyl silicone rubber, 1-3 parts sulfur, 1-5 parts nano zinc oxide, 1-3 parts stearic acid, 2-5 parts antioxidant, 45-70 parts carbon black, 1-4 parts vulcanization accelerator, 2-5 parts plasticizer, and 4-7 parts organic-inorganic hybrid agent. By introducing organic-inorganic hybrid agents and using a reasonable and scientific formulation, this invention enables the silicone rubber to possess not only good flame retardant properties but also excellent mechanical properties, thereby improving its service life.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of silicone rubber, and particularly relates to a silicone rubber and a preparation method thereof. BACKGROUND

[0002] Silicone rubber is a kind of semi-organic and semi-inorganic high molecular material, the main chain of the molecular chain is alternately composed of silicon atoms and oxygen atoms, and the silicon atoms are connected with two organic side groups, so the silicone rubber has the characteristics of organic and inorganic polymers and is one of the most important products of polysiloxane. The silicone rubber has excellent insulation, shock resistance, pressure resistance, wear resistance and good biological properties, and is applied to the fields of building, machinery, electronics, chemical industry and aerospace.

[0003] The silicone rubber has poor high-temperature resistance and is easy to burn when encountering fire. At present, magnesium oxide, titanium oxide, cerium oxide and other metal compounds can be added as heat resistance improvers to improve the heat resistance of the silicone rubber composition, so that the silicone rubber has small physical property change under high temperature conditions. However, most of the metals are expensive and have large fluctuations, which easily leads to high production cost of the silicone rubber and limits the application of the silicone rubber.

[0004] A patent application file with the publication number CN102585515A discloses a fire-resistant silicone rubber, which comprises methyl vinyl raw rubber 100±2.55 parts by weight, hydroxyl silicone oil 2.9±0.1 parts, hydrogen-containing silicone oil 0.36±0.02 parts, a fire-resistant component, the fire-resistant component comprising: magnesium hydroxide 120-140 parts, mica powder 15-20 parts, silicon carbide 6-10 parts, platinum compound 0.6-0.9 parts, potassium nitrate 1-1.5 parts; white carbon black 50±2 parts, internal release agent 0.8±0.05 parts, silane coupling agent 0.5-1 part; the silicone rubber has good flame retardance. However, the fire-resistant component such as mica powder and magnesium hydroxide has a high amount in the technical solution, and there is a risk of agglomeration due to strong inter-particle force, which affects the uniform dispersion of the component in the matrix. If the dispersion is not uniform under high filling amount, the local fire-resistant component may be enriched, which affects the physical properties and fire-resistant stability of the material. SUMMARY

[0005] The existing silicone rubber has the problem of easy agglomeration of the flame-retardant component. In order to solve the problem, the application provides a silicone rubber and a preparation method thereof.

[0006] In order to achieve the purpose of the application, the following technical solutions are adopted in the application:

[0007] In a first aspect, the application provides a silicone rubber, which is composed of the following components in mass parts:

[0008] Methyl vinyl silicone rubber 90-100 parts, sulfur 1-3 parts, nano zinc oxide 1-5 parts, stearic acid 1-3 parts, antioxidant 2-5 parts, carbon black 35-50 parts, vulcanization accelerator 1-4 parts, plasticizer 2-5 parts, organic-inorganic hybrid agent 4-7 parts;

[0009] The organic-inorganic hybrid agent is prepared by uniformly mixing modified polyether polyol, 4,4'-diphenyl methane diisocyanate, porous nanocomposite and anhydrous tetrahydrofuran, warming and reacting, and vacuum solidification.

[0010] By adopting the above technical scheme, methyl vinyl silicone rubber is used as a basic base material, and is matched with carbon black, so that the tensile strength of the material can be effectively improved, and the silicone rubber is not easy to be damaged when bearing external force; sulfur and vulcanization accelerator can make the rubber molecules form a stable cross-linked structure, further enhance the stability of the mechanical properties, and stearic acid can improve the dispersibility of each component, indirectly improve the mechanical properties; the antioxidant can effectively inhibit or delay the aging phenomenon of the silicone rubber caused by light, oxygen and other factors during use; the plasticizer can increase the plasticity and flowability of the silicone rubber; the added organic-inorganic hybrid agent can play a flame-retardant role during combustion, and delay the combustion speed of the material.

[0011] Preferably, the mass ratio of the modified polyether polyol to 4,4'-diphenyl methane diisocyanate is 50:(4-4.8); and the amount of the porous nanocomposite is 10%-15% of the mass of the modified polyether polyol.

[0012] By adopting the above technical scheme, the hydroxyl groups in the modified polyether polyol can be completely reacted under the above ratio of the modified polyether polyol to 4,4'-diphenyl methane diisocyanate, and the slightly excessive 4,4'-diphenyl methane diisocyanate can be further cross-linked to form a more compact three-dimensional network structure, thereby enhancing the chemical stability of the hybrid agent; if the amount of the porous nanocomposite is too low, the mechanical properties are not obviously improved; and if the amount of the porous nanocomposite is too high, the compatibility is easily affected.

[0013] Preferably, the reaction time is 7-8h.

[0014] By adopting the above technical scheme, the three-dimensional network structure generated in the reaction time is more complete, and the chemical stability and mechanical properties of the hybrid agent are optimal.

[0015] Preferably, the preparation method of the porous nanocomposite comprises the following steps:

[0016] The porous nanocomposite is obtained by uniformly mixing alpha-Al2O3, nano-SiO2, Y2O3, PMMA microspheres, ammonium citrate and anhydrous ethanol, freeze-drying, tabletting, and sintering.

[0017] Preferably, the mass ratio of the alpha-Al2O3 to nano-SiO2 is (2-5) : 1, the amount of Y2O3 is 2%-4% of the total mass of the alpha-Al2O3 and nano-SiO2, and the PMMA microspheres are 10%-12% of the total mass of the alpha-Al2O3, nano-SiO2 and Y2O3.

[0018] By adopting the technical scheme, the mechanical properties of the composite material are excellent when the mass ratio of the alpha-Al2O3 to nano-SiO2 is (2-5) : 1, and the grain size is refined and the mechanical properties of the material are improved by adding Y2O3.

[0019] Preferably, the modified polyether polyol is obtained by heating reaction of melamine-formaldehyde condensate and polyether polyol.

[0020] By adopting the technical scheme, the melamine-formaldehyde condensate contains nitrogen elements and a cyclic structure, and the modified polyether polyol obtained after reaction with the polyether polyol has flexibility and flame retardance of the organic chain segment.

[0021] Preferably, the temperature of the reaction is 80-85℃, and the time of the reaction is 9-10h.

[0022] The polyether polyol is polyether polyol 330N, the functionality is 3, and the molecular weight is 3000.

[0023] By adopting the technical scheme, the reaction can be orderly carried out and the modified polyether polyol is formed in the temperature and time range.

[0024] Preferably, the melamine-formaldehyde condensate is obtained by reacting formaldehyde and melamine at a pH value of 8-9 and a temperature of 70-75℃ for 20-30min, and the molar ratio of formaldehyde to melamine is 1 : (1-1.3).

[0025] By adopting the technical scheme, the aldehyde group of formaldehyde and the amino group of melamine can generate an oligomeric condensate with a regular structure under the reaction condition, and the nitrogen element content in the product is sufficient to give the subsequent modified polyether polyol excellent flame retardance.

[0026] Preferably, the antioxidant is obtained by mixing antioxidant 4010NA and antioxidant RD at a mass ratio of (1-2) : 1.

[0027] By adopting the technical scheme, when the amount of the antioxidant 4010NA and the antioxidant RD is 1:1, the synergistic effect of the two is optimal, and the two are easy to disperse and have good compatibility in the rubber compound.

[0028] In the second aspect, the application provides a preparation method of the silicone rubber, comprising the following steps:

[0029] The methyl vinyl silicone rubber is added into an open mill, then nano zinc oxide, stearic acid, antioxidant, plasticizer are added, followed by carbon black, organic-inorganic hybrid agent, and finally sulfur and vulcanization accelerator are added, and after uniform mixing, the product is pressed into a sheet, vulcanized, discharged, and the silicone rubber is obtained.

[0030] By adopting the technical scheme, the feeding sequence of the silicone rubber is optimized, the adverse interaction between components is reduced, the safety and processing stability of the mixing process are ensured, the preparation method is simple and efficient, and the product quality is controllable.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] (1) In the synthesis of polyurethane, the porous nano composite material is directly added, and the polymer chain segment will be wound in the surface channel of the porous nano composite material, increasing the interfacial bonding force between them, so that the porous nano composite material is not easy to slip in the polyurethane;

[0033] (2) The nitrogen atom is further introduced into the polyether polyol, increasing the molecular chain rigidity; melamine will decompose and release non-combustible gases such as nitrogen when heated, and the non-combustible gases can dilute the oxygen concentration and hinder the continuous combustion; at the same time, melamine will absorb heat during decomposition, reducing the temperature of the material and making it difficult to reach the combustion condition; in addition, the nitrogen-containing residue formed after the decomposition of melamine remains on the surface of the silicone rubber, which can play a role in heat insulation and oxygen insulation, further preventing the spread of combustion;

[0034] (3) The organic-inorganic hybrid agent prepared by the present application has the following advantages: the nitrogen atom in the organic phase modified polyether polyol has flame retardancy; the inorganic phase porous nano composite material has high melting point, high hardness and excellent wear resistance, and also has good compatibility, avoiding the problems of easy agglomeration and difficult dispersion of single inorganic material in the rubber system;

[0035] (4) The silicone rubber provided by the present application has excellent mechanical properties in addition to good flame retardant properties by introducing the organic-inorganic hybrid agent and reasonable and scientific proportioning, which improves the service life of the silicone rubber; and the silicone rubber obtained by the present application is environmentally friendly and does not cause environmental pollution. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The SEM image of the porous nano composite material of the present application;

[0037] Figure 2 The infrared spectrum of the organic-inorganic hybrid agent of the present application. DETAILED DESCRIPTION

[0038] The technical solutions of the present application will be explained in detail below with reference to several representative embodiments of the present application.

[0039] The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0040] Example 1

[0041] The silicone rubber of this example is composed of the following components by mass:

[0042] Methyl vinyl silicone rubber 10 kg, sulfur 0.1 kg, nano zinc oxide 0.3 kg, stearic acid 0.3 kg, antioxidant 4010NA 0.2 kg, antioxidant RD 0.2 kg, carbon black N234 5 kg, vulcanization accelerator NS 0.2 kg, plasticizer DOP 0.4 kg, organic-inorganic hybrid agent 0.7 kg;

[0043] The preparation method of the organic-inorganic hybrid agent of this example is as follows:

[0044] (1) Preparation of modified polyether polyol

[0045] Add 7.5 mL of 37% mass fraction formaldehyde aqueous solution to a three-necked flask, slowly add sodium hydroxide aqueous solution to the formaldehyde aqueous solution, adjust the pH value to 8, add 12.62 g of melamine to the formaldehyde aqueous solution, heat and stir to warm up to 70℃ for 20 min; after the reaction is completed, directly add 300 g of polyether polyol 330N, warm up to 85℃, and react for 9 h, then adjust the pH value to 9 with sodium hydroxide aqueous solution; after the reaction is completed, dry to obtain the modified polyether polyol;

[0046] (2) Preparation of porous nanocomposite

[0047] Add 4 g of α-A12O3, 2 g of nano-SiO2, 0.18 g of Y2O3, 0.62 g of PMMA microspheres, 0.1 g of ammonium citrate, and 50 mL of anhydrous ethanol to a ball mill in sequence, ball mill at a speed of 300 r / min for 12 h, pause every 2 h, and ultrasonically disperse for 30 min with an ultrasonic instrument; after ball milling, freeze-dry, pass through a 100-mesh sieve, press into a tablet, transfer to a muffle furnace, warm up to 300℃ at a rate of 5℃ / min, keep warm for 30 min; warm up to 600℃ at a rate of 2℃ / min, keep warm for 1 h; warm up to 1300℃ at a rate of 5℃ / min, keep warm for 1 h, and naturally cool to room temperature to obtain the porous nanocomposite.

[0048] The SEM image of the porous nanocomposite is shown in Figure 1 , Figure 1The middle particles are accumulated to form irregular pores, and present a porous structure.

[0049] (3) Preparation of the organic-inorganic hybrid agent

[0050] 50 g of modified polyether polyol, 4.7 g of 4,4'-diphenyl methane diisocyanate, 5 g of porous nanocomposite, and 65 mL of anhydrous tetrahydrofuran were sequentially added into a three-necked flask, and reacted for 7 h under heating. After the reaction, the tetrahydrofuran was removed, and the organic-inorganic hybrid agent was obtained by curing at 160 °C under vacuum for 24 h.

[0051] The infrared spectrum of the organic-inorganic hybrid agent is shown in Figure 2 , Figure 2 The characteristic vibration peak of -N-H is at 3347 cm -1 , the characteristic vibration peak of -C-H is at 2953 cm -1 , the characteristic vibration peak of residual -NCO is at 2282 cm -1 , the characteristic vibration peak of C=O is at 1721 cm -1 , the characteristic vibration peak of C-N is at 1526 cm -1 , and the vibration absorption peaks of -C-O-C- are at 1221 cm -1 and 1151 cm -1 .

[0052] The preparation method of the silicone rubber of the present embodiment is as follows:

[0053] The methyl vinyl silicone rubber was added into an open mill, followed by the addition of nano zinc oxide, stearic acid, antioxidant 4010NA, antioxidant RD, plasticizer DOP, then carbon black N234 and the organic-inorganic hybrid agent, and finally sulfur and vulcanization accelerator NS. After mixing at 60 °C for 4 h, the mixture was sheeted, and placed at room temperature for 24 h. The flat plate vulcanizer was heated to 180 °C for 10 min, and then transferred to an oven, and heated to 200 °C for secondary vulcanization for 4 h, to obtain the silicone rubber.

[0054] Example 2

[0055] The silicone rubber of the present embodiment is composed of the following components by mass:

[0056] Methyl vinyl silicone rubber 9 kg, sulfur 0.2 kg, nano zinc oxide 0.1 kg, stearic acid 0.2 kg, antioxidant 4010NA 0.2 kg, antioxidant RD 0.15 kg, carbon black N234 3.5 kg, vulcanization accelerator NS 0.4 kg, plasticizer DOP 0.2 kg, and organic-inorganic hybrid agent 0.6 kg.

[0057] The preparation method of the organic-inorganic hybrid agent of the present embodiment is as follows:

[0058] (1) Preparation of modified polyether polyol

[0059] 7.5 mL of 37% mass fraction formaldehyde aqueous solution was added into a three-necked flask, sodium hydroxide aqueous solution was slowly added into the formaldehyde aqueous solution, the pH value was adjusted to 8, 16.36 g of melamine was added into the formaldehyde aqueous solution, heating and stirring was performed to elevate the temperature to 75℃, and reaction was performed for 25 min; after the reaction was completed, 300 g of polyether polyol 330N was directly added, the temperature was elevated to 82℃, and reaction was performed for 10 h, then sodium hydroxide aqueous solution was used to adjust the pH value to 9; after the reaction was completed, drying was performed to obtain the modified polyether polyol;

[0060] (2) Preparation of porous nanocomposite

[0061] 6 g of α-A12O3, 2 g of nano-SiO2, 0.28 g of Y2O3, 0.91 g of PMMA microspheres, 0.1 g of ammonium citrate and 50 mL of anhydrous ethanol were sequentially added into a ball mill, ball milling was performed at a rotating speed of 300 r / min for 12 h, the ball milling was paused every 2 h, and ultrasonic dispersion was performed for 30 min by using an ultrasonic instrument; after the ball milling was completed, freeze-drying was performed, 100-mesh sieving was performed, tabletting was performed, and the tablet was transferred into a muffle furnace, the temperature was elevated to 300℃ at a temperature elevation rate of 5℃ / min, and the temperature was maintained for 30 min; the temperature was elevated to 600℃ at a temperature elevation rate of 2℃ / min, and the temperature was maintained for 1 h; the temperature was elevated to 1300℃ at a temperature elevation rate of 5℃ / min, and the temperature was maintained for 1 h, and natural cooling was performed to room temperature, and the porous nanocomposite was obtained.

[0062] (3) Preparation of organic-inorganic hybrid agent

[0063] 50 g of modified polyether polyol, 4.4 g of 4,4'-diphenyl methane diisocyanate, 6 g of porous nanocomposite and 65 mL of anhydrous tetrahydrofuran were sequentially added into a three-necked flask, and reaction was performed for 7 h, after the reaction was completed, the tetrahydrofuran was removed, and solidification was performed under vacuum at 160℃ for 24 h to obtain the organic-inorganic hybrid agent.

[0064] The preparation method of the silicone rubber of the embodiment is specifically as follows:

[0065] The methyl vinyl silicone rubber was added into an open mill, and then nano-zinc oxide, stearic acid, antioxidant 4010NA, antioxidant RD, plasticizer DOP, carbon black N234, organic-inorganic hybrid agent, sulfur and vulcanization accelerator NS were sequentially added, tabletting was performed after 4 h of mixing at 60℃, and the tablet was placed at room temperature for 24 h, the flat plate vulcanizer was elevated to 180℃ for vulcanization for 10 min, the tablet was transferred into an oven, the temperature was elevated to 200℃, and secondary vulcanization was performed for 4 h, and the silicone rubber was obtained.

[0066] Example 3

[0067] A silicone rubber of this embodiment is composed of the following components by mass:

[0068] methyl vinyl silicone rubber 9.6 kg, sulfur 0.2 kg, nano zinc oxide 0.2 kg, stearic acid 0.2 kg, antioxidant 4010NA 0.1 kg, antioxidant RD 0.1 kg, carbon black N234 4.5 kg, vulcanization accelerator NS 0.1 kg, plasticizer DOP 0.3 kg, organic-inorganic hybrid agent 0.5 kg;

[0069] A preparation method of an organic-inorganic hybrid agent of this embodiment, the specific steps are as follows:

[0070] (1) Preparation of modified polyether polyol

[0071] 7.5 mL of 37% mass fraction formaldehyde aqueous solution was added to a three-necked flask, and sodium hydroxide aqueous solution was slowly added to the formaldehyde aqueous solution to adjust the pH value to 9. 15.14 g of melamine was added to the formaldehyde aqueous solution, heated and stirred to 73℃, and reacted for 30 min. After the reaction was completed, 300 g of polyether polyol 330N was directly added, the temperature was raised to 85℃, and the reaction was carried out for 9 h, and then the pH value was adjusted to 9 with sodium hydroxide aqueous solution. After the reaction was completed, it was dried to obtain a modified polyether polyol.

[0072] (2) Preparation of porous nano-composite material

[0073] 5 g of α-A12O3, 2 g of nano-SiO2, 0.21 g of Y2O3, 0.76 g of PMMA microspheres, 0.1 g of ammonium citrate and 50 mL of anhydrous ethanol were sequentially added to a ball mill, and ball milled at a speed of 300 r / min for 12 h, with a pause every 2 h. Ultrasonic dispersion was carried out for 30 min with an ultrasonic instrument. After ball milling, freeze-drying was carried out, sieving was carried out through a 100 mesh sieve, tabletting was carried out, and then transferred to a muffle furnace, heated to 300℃ at a heating rate of 5℃ / min, and kept for 30 min. The temperature was raised to 600℃ at a heating rate of 2℃ / min, and kept for 1 h. The temperature was raised to 1300℃ at a heating rate of 5℃ / min, and kept for 1 h. The temperature was naturally cooled to room temperature, and a porous nano-composite material was obtained.

[0074] (3) Preparation of organic-inorganic hybrid agent

[0075] 50 g of modified polyether polyol, 4 g of 4,4'-diphenyl methane diisocyanate, 7.5 g of porous nano-composite material, and 65 mL of anhydrous tetrahydrofuran were sequentially added to a three-necked flask, and reacted at an elevated temperature for 8 h. After the reaction was completed, the tetrahydrofuran was removed, and the organic-inorganic hybrid agent was obtained by curing at 160℃ under vacuum for 24 h.

[0076] A preparation method of a silicone rubber of this embodiment, the specific steps are as follows:

[0077] Into an open mill, methyl vinyl silicone rubber was added, followed by nano zinc oxide, stearic acid, antioxidant 4010NA, antioxidant RD, plasticizer DOP, then carbon black N234, organic-inorganic hybrid agent, and finally sulfur and vulcanization accelerator NS. After mixing at 60°C for 4 h, the mixture was sheeted, and the sheet was allowed to stand at room temperature for 24 h. The sheet was then transferred to a flat plate vulcanizer, which was heated to 180°C for 10 min, and then to an oven, which was heated to 200°C for 4 h for secondary vulcanization, to obtain the silicone rubber.

[0078] Example 4

[0079] The silicone rubber of this example was prepared from the following components:

[0080] methyl vinyl silicone rubber 9.5 kg, sulfur 0.3 kg, nano zinc oxide 0.4 kg, stearic acid 0.1 kg, antioxidant 4010NA 0.1 kg, antioxidant RD 0.1 kg, carbon black N234 4 kg, vulcanization accelerator NS 0.3 kg, plasticizer DOP 0.05 kg, and organic-inorganic hybrid agent 0.6 kg;

[0081] The method for preparing the organic-inorganic hybrid agent of this example included the following steps:

[0082] (1) Preparation of modified polyether polyol

[0083] Into a three-necked flask, 7.5 mL of 37% formaldehyde aqueous solution was added, and then sodium hydroxide aqueous solution was slowly added to the formaldehyde aqueous solution to adjust the pH value to 9. Then, 12.62 g of melamine was added to the formaldehyde aqueous solution, and the mixture was heated and stirred to 75°C for 20 min. After the reaction was completed, 300 g of polyether polyol 330N was added, and the mixture was heated to 85°C for 9 h. Then, the pH value was adjusted to 9 using sodium hydroxide aqueous solution. After the reaction was completed, the modified polyether polyol was obtained by drying.

[0084] (2) Preparation of porous nano composite material

[0085] Into a ball mill, 10 g of α-A12O3, 2 g of nano SiO2, 0.24 g of Y2O3, 1.45 g of PMMA microspheres, 0.1 g of ammonium citrate, and 50 mL of anhydrous ethanol were sequentially added, and the mixture was ball milled at a rotation speed of 300 r / min for 12 h, with a pause every 2 h. The mixture was ultrasonically dispersed for 30 min using an ultrasonic instrument. After the ball milling was completed, the mixture was freeze-dried, sieved through a 100-mesh sieve, sheeted, and transferred to a muffle furnace. The temperature was increased to 300°C at a rate of 5°C / min, and the mixture was kept at this temperature for 30 min. The temperature was increased to 600°C at a rate of 2°C / min, and the mixture was kept at this temperature for 1 h. The temperature was increased to 1300°C at a rate of 5°C / min, and the mixture was kept at this temperature for 1 h. The mixture was naturally cooled to room temperature to obtain the porous nano composite material.

[0086] (3) Preparation of organic-inorganic hybrid agent

[0087] 50 g of modified polyether polyol, 4.6 g of 4,4'-diphenyl methane diisocyanate, 5 g of porous nanocomposite, and 65 mL of anhydrous tetrahydrofuran were sequentially added to a three-necked flask, and the reaction was carried out at an elevated temperature for 7 h. After the reaction was completed, the tetrahydrofuran was removed, and the organic-inorganic hybrid agent was obtained by curing at 160°C under vacuum for 24 h.

[0088] The preparation method of the silicone rubber of the present embodiment is as follows:

[0089] The methyl vinyl silicone rubber, nano zinc oxide, stearic acid, antioxidant 4010NA, antioxidant RD, plasticizer DOP, carbon black N234, and organic-inorganic hybrid agent were sequentially added to the open mill, and then sulfur and vulcanization accelerator NS were added. After mixing at 60°C for 4 h, the mixture was sheeted, and the sheet was placed at room temperature for 24 h. The sheet was then vulcanized in a flat plate vulcanizer at 180°C for 10 min, and then transferred to an oven, and the temperature was raised to 200°C for secondary vulcanization for 4 h, thereby obtaining the silicone rubber.

[0090] Example 5

[0091] The silicone rubber of the present embodiment is composed of the following components by mass:

[0092] methyl vinyl silicone rubber 10 kg, sulfur 0.2 kg, nano zinc oxide 0.5 kg, stearic acid 0.3 kg, antioxidant 4010NA 0.25 kg, antioxidant RD 0.25 kg, carbon black N234 4.5 kg, vulcanization accelerator NS 0.2 kg, plasticizer DOP 0.3 kg, and organic-inorganic hybrid agent 0.4 kg;

[0093] The preparation method of the organic-inorganic hybrid agent of the present embodiment is as follows:

[0094] (1) Preparation of modified polyether polyol

[0095] 7.5 mL of a 37% mass fraction formaldehyde aqueous solution was added to a three-necked flask, and a sodium hydroxide aqueous solution was slowly added to the formaldehyde aqueous solution to adjust the pH value to 8. Then, 12.62 g of melamine was added to the formaldehyde aqueous solution, and the mixture was heated and stirred to raise the temperature to 70°C for reaction for 30 min. After the reaction was completed, 300 g of polyether polyol 330N was directly added, and the temperature was raised to 80°C for reaction for 10 h. Then, the pH value was adjusted to 9 using a sodium hydroxide aqueous solution. After the reaction was completed, the modified polyether polyol was obtained by drying.

[0096] (2) Preparation of porous nanocomposite

[0097] Into a ball mill, 8 g of α-A12O3, 2 g of nano-SiO2, 0.4 g of Y2O3, 1.2 g of PMMA microspheres, 0.1 g of ammonium citrate and 50 mL of anhydrous ethanol were sequentially added, and ball milling was performed at a rotation speed of 300 r / min for 12 h, with a pause every 2 h, and ultrasonic dispersion was performed for 30 min by using an ultrasonic instrument; after the ball milling was completed, freeze-drying was performed, sieving was performed through a 100-mesh sieve, tabletting was performed, and the tablet was transferred into a muffle furnace, and heated to 300 ℃ at a heating rate of 5 ℃ / min, and kept for 30 min; heated to 600 ℃ at a heating rate of 2 ℃ / min, and kept for 1 h; heated to 1300 ℃ at a heating rate of 5 ℃ / min, and kept for 1 h, and naturally cooled to room temperature, to obtain a porous nano-composite material.

[0098] (3) Preparation of the organic-inorganic hybrid agent

[0099] Into a three-necked flask, 50 g of the modified polyether polyol, 4.2 g of 4,4'-diphenyl methane diisocyanate, 7 g of the porous nano-composite material and 65 mL of anhydrous tetrahydrofuran were sequentially added, and heating reaction was performed for 8 h, and after the reaction was completed, the tetrahydrofuran was removed, and solidification was performed under vacuum at 160 ℃ for 24 h to obtain the organic-inorganic hybrid agent.

[0100] The preparation method of the silicone rubber of the present embodiment is as follows:

[0101] Into an open mill, methyl vinyl silicone rubber was added, and then nano-zinc oxide, stearic acid, antioxidant 4010NA, antioxidant RD and plasticizer DOP were added, followed by the addition of carbon black N234 and the organic-inorganic hybrid agent, and finally sulfur and vulcanization accelerator NS were added, and after mixing at 60 ℃ for 4 h, tabletting was performed, and the tablet was placed at room temperature for 24 h, the flat plate vulcanizer was heated to 180 ℃ for vulcanization for 10 min, and then the tablet was transferred into an oven, and heating was performed to 200 ℃ for secondary vulcanization for 4 h, to obtain the silicone rubber.

[0102] Comparative Example 1

[0103] The silicone rubber of the present comparative example is different from that of Example 1 in that the organic-inorganic hybrid agent is replaced by an equal amount of modified polyether polyol, and the rest is the same as in Example 1.

[0104] Comparative Example 2

[0105] The silicone rubber of the present comparative example is different from that of Example 1 in that the organic-inorganic hybrid agent is replaced by an equal amount of porous nano-composite material, and the rest is the same as in Example 1.

[0106] Comparative Example 3

[0107] The silicone rubber of the present comparative example is different from that of Example 1 in that the organic-inorganic hybrid agent is not added to the silicone rubber, and the rest is the same as in Example 1.

[0108] The silicone rubbers prepared in the above Examples 1-5 and Comparative Examples 1-3 were tested according to relevant standards, and the silicone rubber performance test results are shown in Table 1.

[0109] Table 1 Test results

[0110]

[0111] As can be seen from Table 1, the silicone rubber provided by the present application can further improve the flame retardant performance of the silicone rubber while improving the mechanical strength of the silicone rubber.

[0112] The above has made an exemplary description of the present application, it should be explained that, without departing from the core of the present application, any simple transformation, modification or other equivalent replacement which can not cost the creative labor of the person skilled in the art, falls into the protection scope of the present application.

Claims

1. A silicone rubber, characterized by, The silicone rubber is composed of the following components by mass fraction: Methyl vinyl silicone rubber 90-100 parts, sulfur 1-3 parts, nano zinc oxide 1-5 parts, stearic acid 1-3 parts, antioxidant 2-5 parts, carbon black 35-50 parts, vulcanization accelerator 1-4 parts, plasticizer 2-5 parts, organic-inorganic hybrid agent 4-7 parts; The organic-inorganic hybrid agent is prepared by uniformly mixing modified polyether polyol, 4,4'-diphenyl methane diisocyanate, porous nanocomposite and anhydrous tetrahydrofuran, heating and reacting, and vacuum solidification. The preparation method of the porous nanocomposite comprises the following steps: Mixing α-Al2O3, nano SiO2, Y2O3, PMMA microspheres, ammonium citrate and anhydrous ethanol uniformly, freeze-drying, tabletting, sintering, and obtaining the porous nanocomposite. The modified polyether polyol is prepared by heating reaction of melamine-formaldehyde condensate and polyether polyol. The mass ratio of the modified polyether polyol to 4,4'-diphenyl methane diisocyanate is 50:(4-4.8), and the amount of the porous nanocomposite is 10%-15% of the mass of the modified polyether polyol.

2. A silicone rubber according to claim 1 characterised in that, In the preparation of the organic-inorganic hybrid agent, the reaction time is 7-8h.

3. A silicone rubber according to claim 1, characterised in that The mass ratio of the α-Al2O3 to nano SiO2 is (2-5):1, the amount of Y2O3 is 2%-4% of the total mass of α-Al2O3 and nano SiO2, and the amount of PMMA microspheres is 10%-12% of the total mass of α-Al2O3, nano SiO2 and Y2O3.

4. A silicone rubber according to claim 1, characterised in that In the preparation of the modified polyether polyol, the reaction temperature is 80-85℃, and the reaction time is 9-10h.

5. A silicone rubber according to claim 1, characterised in that The melamine-formaldehyde condensate is prepared by reacting formaldehyde and melamine at a pH value of 8-9 and a temperature of 70-75℃ for 20-30min, wherein the molar ratio of formaldehyde to melamine is 1:(1-1.3).

6. A silicone rubber according to claim 1, characterised in that The antioxidant is prepared by mixing antioxidant 4010NA and antioxidant RD according to a mass ratio of (1-2):

1.

7. A process for the preparation of a silicone rubber according to any one of claims 1 to 6, characterised in that, The method comprises the following steps: Add methyl vinyl silicone rubber to the open mill, then add nano zinc oxide, stearic acid, antioxidant and plasticizer, followed by adding carbon black and organic-inorganic hybrid agent, and finally adding sulfur and vulcanization accelerator, mix uniformly, tablet, vulcanize, discharge, and obtain the silicone rubber.

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