High-hardness silica gel strip and preparation method thereof

Abstract

The invention relates to the technical field of rubber, in particular to a high-hardness silica gel strip and a preparation method thereof. The silica gel strip comprises a silica gel main body, a sulfurizing modified stainless steel wire and a winding fiber layer. The silica gel main body is prepared from raw materials such as methyl vinyl silicone rubber and fumed silica, stainless steel wires modified by sulfurizing are embedded in the silica gel main body, and the winding fiber layer is formed by spirally coating the surface of the silica gel main body with aramid fibers. Through the enhanced synergistic effect of the sulfurizing modified stainless steel wires and the winding fiber layer, the silica gel strip shows excellent tensile strength, bending strength and fatigue life, can be widely applied to the fields of photovoltaic modules, aerospace, automobile manufacturing and the like, remarkably prolongs the service life and reduces the maintenance cost.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber, and particularly relates to a high-hardness silicone strip and a preparation method thereof. Background Art

[0002] As an important elastomer material, the silicone strip is widely used in the fields of photovoltaic module manufacturing, aerospace, automotive manufacturing, electronic equipment protection, etc. due to its excellent high and low temperature resistance, chemical stability and good elasticity. However, with the complication of application scenarios, some problems have emerged in the actual use of traditional silicone strips. Especially under high-intensity stretching, bending or complex stress environments, phenomena such as deformation, fracture or delamination are likely to occur, seriously affecting its service life and reliability.

[0003] Currently, the research on improving the performance of silicone strips mainly focuses on the following aspects: one is to improve its mechanical properties by modifying the silicone rubber matrix, such as improving the strength and toughness of silicone rubber by introducing nano-fillers, reinforcing fibers or chemical cross-linking agents; the other is to enhance its structural stability by embedding metal wires or fiber layers in the silicone strip. However, these methods still have certain limitations in actual applications. For example, although embedding metal wires can significantly improve the tensile strength of the silicone strip, due to the weak interfacial bonding force between the metal wires and the silicone rubber matrix, interfacial delamination or stress concentration is likely to occur, thus reducing the overall performance of the composite material. In addition, although traditional metal wire surface treatment methods (such as pickling, phosphating, etc.) can improve the interfacial bonding force to a certain extent, their effects are limited and it is difficult to meet the high-performance requirements under complex stress environments. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a high-hardness silicone strip and a preparation method thereof to improve the mechanical properties and structural stability of the silicone strip and meet the requirements of complex stress environments.

[0005] Based on the above purpose, the present invention provides a high-hardness silicone strip, which includes a silicone main body, sulfurized modified stainless steel wires and a winding fiber layer.

[0006] Preferably, the silicone main body is prepared from the following raw materials: 80-120 parts of methyl vinyl silicone rubber, 6-10 parts of hexamethyldisilazane, 30-40 parts of fumed silica, 0.3-1 part of hydrogen-containing silicone oil and 0.1-0.3 part of platinum catalyst.

[0007] Preferably, the model of the methyl vinyl silicone rubber is 110-2.

[0008] Preferably, the specific surface area of the fumed silica is 300-400m 2 / g.

[0009] Preferably, the hydrogen-containing silicone oil has a viscosity of 80-90 at 25°C and a hydrogen content of 0.3%-0.8%.

[0010] Furthermore, sulfurized modified stainless steel wires are evenly distributed axially inside the silicone rubber main body at a density of 3-5 wires per square centimeter.

[0011] Furthermore, the winding fiber layer is formed by aramid fibers spirally wrapping around the outer surface of the silicone rubber main body.

[0012] Preferably, the thickness of the winding fiber layer is 0.2-0.3 mm.

[0013] Furthermore, the preparation steps of the sulfurized modified stainless steel wires are as follows:

[0014] (1) Immerse the stainless steel wires into a sulfuric acid solution, perform impregnation treatment, wash with water, and dry to obtain pretreated stainless steel wires;

[0015] (2) Add thiourea and dimethyldiallylammonium chloride into isopropanol to obtain an adsorption solution, immerse the pretreated stainless steel wires into the adsorption solution, perform impregnation treatment, and dry under vacuum to obtain surface-treated stainless steel wires;

[0016] (3) Place the surface-treated stainless steel wires in a tubular furnace for sulfurization treatment to obtain sulfurized modified stainless steel wires.

[0017] Preferably, the concentration of the sulfuric acid solution in step (1) is 8wt%-12wt%.

[0018] Preferably, the liquid-solid ratio of the impregnation treatment in step (1) is 15-25:1, and the time is 8-12 min.

[0019] Preferably, the diameter of the stainless steel wires in step (1) is 0.2-0.5 mm.

[0020] Preferably, the weight ratio of thiourea, dimethyldiallylammonium chloride and isopropanol in step (2) is 10-15:5-10:300-500.

[0021] Preferably, the liquid-solid ratio of the impregnation treatment in step (2) is 15-25:1, and the time is 3-5 h.

[0022] Preferably, the atmosphere for the sulfurization treatment in step (3) is a H2S / N2 mixed gas with a volume ratio of 1:8-10, a flow rate of 180-220 mL / min, a pressure inside the tube of 0.09-0.11 MPa, heating from room temperature to 195-205°C at a rate of 3-10°C / min, and holding for 20-40 min.

[0023] Furthermore, the present invention also provides a method for preparing a high-hardness silicone strip, which is characterized by comprising the following steps:

[0024] S1: Mix methyl vinyl silicone rubber, hexamethyldisilazane, fumed silica and hydrogen-containing silicone oil, stir at a speed of 150 - 250 rpm for 20 - 30 min, then add a platinum catalyst and continue stirring for 10 - 20 min to obtain a rubber compound;

[0025] S2: Load the rubber compound into a twin-screw extruder with a barrel temperature of 155 - 165 °C. During the continuous extrusion through a die head with a diameter of 8 - 12 mm, synchronously use a wire feeding device controlled by a servo to embed sulfurized modified stainless steel wires into the interior of the colloid at equal intervals along the extrusion direction to obtain a silicone main body;

[0026] S3: Use a winding machine to helically wrap aramid fibers on the outer surface of the silicone main body at a winding angle of 50 - 60°, with a winding tension of 4 - 5 N and a wire guiding nozzle moving speed of 110 - 130 mm / s to form a wound fiber layer;

[0027] S4: Subject the silicone main body with the wound fiber layer to segmented vulcanization. In the first stage, the temperature is 165 - 175 °C and the time is 4 - 6 min. In the second stage, the temperature is 180 - 190 °C and the time is 10 - 14 min. In the third stage, treat it at 195 - 205 °C for 15 - 25 min to obtain a high-hardness silicone strip.

[0028] Advantages of the present invention:

[0029] Through the internal embedding reinforcement of sulfurized stainless steel wires, the silicone strip of the present invention can be bent to a certain extent without breaking while having high hardness, and can meet the requirements of different installation environments. For example, when pressure is applied in a narrow space, it can still maintain good performance and will not be crushed.

[0030] Through the combined action of sulfurized stainless steel wires and the wound fiber layer, the present invention significantly improves the structural stability of the silicone strip. When subjected to large external pressure, tension or impact force, it can effectively disperse stress, prevent the silicone strip from deforming, breaking or delaminating, extend the service life of the silicone strip, and reduce the maintenance cost.

[0031] Through sulfurizing modification, a dense and uniform sulfide layer is formed on the surface of the stainless steel wire. This sulfide layer has high chemical stability and mechanical strength, and can effectively enhance the interfacial bonding force between the stainless steel wire and the silicone rubber matrix. The improvement of this interfacial bonding force not only optimizes the transfer of mechanical properties, but also significantly improves the reliability of the composite material in complex stress environments. In addition, the sulfide layer formed during the sulfurizing modification process can react with the active groups in the silicone rubber matrix through chemical bonding, further enhancing the chemical bonding strength of the interface. At the same time, the nano-scale rough structure of the sulfide layer can also enhance the mechanical anchoring effect of the interface, so that the composite material shows higher strength and durability in mechanical property tests such as tension, bending and fatigue.

[0032] The present invention also further optimizes the chemical properties of the stainless steel wire surface by adding thiourea and dimethyldiallylammonium chloride to the adsorption liquid. The introduction of thiourea promotes the uniform formation of the sulfide layer, while dimethyldiallylammonium chloride forms a stable adsorption layer on the surface of the stainless steel wire through its cationic groups, providing a more uniform reaction interface for the subsequent sulfidation reaction. This synergistic effect significantly improves the interfacial activity of the stainless steel wire surface, thereby further enhancing the bonding force between it and the silicone rubber matrix.

[0033] Through the above modification method, the high-hardness silicone rubber strip prepared by the present invention shows excellent performance in terms of tensile strength, bending strength and fatigue life, and can be widely used in fields with high requirements for protection performance such as photovoltaic module manufacturing, aerospace, automobile manufacturing, and electronic equipment protection. Detailed implementation mode

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments.

[0035] Example 1:

[0036] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 8 wt%, with a liquid-solid ratio of 15:1, immerse for 12 min, then wash with deionized water and dry in vacuum to obtain a pretreated stainless steel wire;

[0037] (2) Add 10 g of thiourea and 5 g of dimethyldiallylammonium chloride to 300 g of isopropanol to obtain an adsorption liquid. Immerse the pretreated stainless steel wire into the adsorption liquid, with a liquid-solid ratio of 15:1, immerse for 3 h, and dry in vacuum to obtain a surface-treated stainless steel wire;

[0038] (3) Place the surface-treated stainless steel wire in a tubular furnace, introduce a mixed gas of H2S / N2 (volume ratio 1:8, total flow rate 180 mL / min), control the pressure inside the tube to be 0.09 MPa, heat from room temperature to 195 °C at a rate of 3 °C / min, and hold for 20 min to obtain sulfurized modified stainless steel wire;

[0039] (4) Mix 80 g of methyl vinyl silicone rubber (type 110-2), 6 g of hexamethyldisilazane, 30 g of fumed silica (specific surface area 380 m 2 / g) and 0.3 g of hydrogen-containing silicone oil (viscosity 85 at 25 °C, hydrogen content 0.5%) and stir at a speed of 150 rpm for 20 min. Then add 0.1 g of platinum catalyst and continue stirring for 10 min to obtain a rubber compound;

[0040] (5) Load the rubber compound into a twin-screw extruder (barrel temperature 155 °C). During the continuous extrusion through a die head with a diameter of 10 mm, simultaneously use a wire feeding device controlled by servo, and embed the sulfurized modified stainless steel wire equidistantly along the extrusion direction into the colloid at an arrangement density of 3 wires / cm 2 to obtain a silicone rubber main body;

[0041] (6) Use a winding machine to helically wrap aramid fiber (model K49, linear density 1680 dtex) on the outer surface of the silicone rubber main body at a winding angle of 55°, with a winding tension of 4 N and a wire guiding nozzle moving speed of 110 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0042] (7) Then perform segmented vulcanization on the silicone rubber main body with the winding fiber layer. In the first stage, the temperature is 165 °C and the time is 6 min. In the second stage, the temperature is 180 °C and the time is 14 min. In the third stage, treat at 195 °C for 25 min to obtain a high-hardness silicone rubber strip.

[0043] Example 2:

[0044] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 10 wt%, with a liquid-solid ratio of 20:1. Immerse for 10 min, then wash with deionized water and dry in vacuum to obtain a pretreated stainless steel wire;

[0045] (2) Add 12 g of thiourea and 8 g of dimethyldiallylammonium chloride to 400 g of isopropanol to obtain an adsorption solution. Immerse the pretreated stainless steel wire into the adsorption solution, with a liquid-solid ratio of 20:1. Immerse for 4 h and dry in vacuum to obtain a surface-treated stainless steel wire;

[0046] (3) Place the surface-treated stainless steel wire in a tubular furnace, introduce a mixed gas of H2S / N2 (volume ratio 1:9, total flow rate 200 mL / min), control the pressure inside the tube to be 0.1 MPa, heat from room temperature to 200 °C at a rate of 5 °C / min, and hold for 30 min to obtain sulfurized modified stainless steel wire;

[0047] (4) Mix 100 g of methyl vinyl silicone rubber (type 110-2), 8 g of hexamethyldisilazane, 35 g of fumed silica (specific surface area 380 m 2 / g), and 0.5 g of hydrogen-containing silicone oil (viscosity 85 at 25 °C, hydrogen content 0.5%) and stir at a speed of 200 rpm for 25 min. Then add 0.2 g of platinum catalyst and continue stirring for 15 min to obtain the rubber compound;

[0048] (5) Load the rubber compound into a twin-screw extruder (barrel temperature 160 °C). During the continuous extrusion through a die head with a diameter of 10 mm, synchronously use a wire feeding device controlled by servo, and embed the sulfurized modified stainless steel wire equidistantly along the extrusion direction into the colloid interior at an arrangement density of 3 pieces / cm 2 to obtain the silicone rubber body;

[0049] (6) Use a winding machine to helically wrap aramid fiber (model K49, linear density 1680 dtex) on the outer surface of the silicone rubber body at a winding angle of 55°, with a winding tension of 4.5 N and a wire guiding nozzle moving speed of 120 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0050] (7) Then perform segmented vulcanization on the silicone rubber body with the winding fiber layer. In the first stage, the temperature is 170 °C and the time is 5 min. In the second stage, the temperature is 185 °C and the time is 12 min. In the third stage, treat at 200 °C for 20 min to obtain a high-hardness silicone rubber strip.

[0051] Example 3:

[0052] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 12 wt%, with a liquid-solid ratio of 25:1, perform immersion treatment for 8 min, then wash with deionized water and dry in vacuum to obtain the pretreated stainless steel wire;

[0053] (2) Add 15 g of thiourea and 10 g of dimethyldiallylammonium chloride to 500 g of isopropanol to obtain the adsorption liquid. Immerse the pretreated stainless steel wire into the adsorption liquid, with a liquid-solid ratio of 25:1, perform immersion treatment for 5 h, and dry in vacuum to obtain the surface-treated stainless steel wire;

[0054] (3) Place the surface-treated stainless steel wire in a tube furnace, introduce a H2S / N2 mixed gas (volume ratio of 1:10, total flow rate of 220 mL / min), control the pressure inside the tube to be 0.11 MPa, heat from room temperature to 205 °C at a rate of 10 °C / min, and hold for 40 min to obtain a sulfurized modified stainless steel wire;

[0055] (4) Mix 120 g of methyl vinyl silicone rubber (type 110-2), 10 g of hexamethyldisilazane, 40 g of fumed silica (specific surface area of 380 m 2 / g) and 1 g of hydrogen-containing silicone oil (viscosity of 85 at 25 °C, hydrogen content of 0.5%) and stir at a speed of 250 rpm for 30 min. Then add 0.3 g of platinum catalyst and continue stirring for 20 min to obtain a rubber compound;

[0056] (5) Load the rubber compound into a twin-screw extruder (barrel temperature of 165 °C). During the continuous extrusion through a die head with a diameter of 10 mm, simultaneously use a wire feeding device controlled by servo to evenly embed the sulfurized modified stainless steel wire into the colloid along the extrusion direction at an arrangement density of 3 pieces / cm 2 to obtain a silicone rubber body;

[0057] (6) Use a winding machine to helically wrap aramid fiber (model K49, linear density of 1680 dtex) on the outer surface of the silicone rubber body at a winding angle of 55°, with a winding tension of 5 N and a wire guiding nozzle moving speed of 130 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0058] (7) Then perform segmented vulcanization on the silicone rubber body with the winding fiber layer. In the first stage, the temperature is 175 °C and the time is 4 min. In the second stage, the temperature is 190 °C and the time is 10 min. In the third stage, treat at 205 °C for 15 min to obtain a high-hardness silicone rubber strip.

[0059] Comparative Example 1:

[0060] The difference between Comparative Example 1 and Example 2 is that the surface-treated stainless steel wire in step (3) is replaced with a pretreated stainless steel wire;

[0061] The specific steps are as follows:

[0062] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 10 wt%, with a liquid-solid ratio of 20:1. After impregnation treatment for 10 min, wash with deionized water and dry in vacuum to obtain a pretreated stainless steel wire;

[0063] (2) Place the pretreated stainless steel wire in a tubular furnace, introduce a mixed gas of H2S / N2 (volume ratio 1:9, total flow rate 200 mL / min), control the pressure inside the tube to be 0.1 MPa, heat from room temperature to 200 °C at a rate of 5 °C / min, and hold for 30 min to obtain a sulfurized modified stainless steel wire;

[0064] (3) Mix 100 g of methyl vinyl silicone rubber (type 110-2), 8 g of hexamethyldisilazane, 35 g of fumed silica (specific surface area 380 m 2 / g) and 0.5 g of hydrogen-containing silicone oil (viscosity 85 at 25 °C, hydrogen content 0.5%) and stir at a speed of 200 rpm for 25 min. Then add 0.2 g of platinum catalyst and continue stirring for 15 min to obtain a rubber compound;

[0065] (4) Load the rubber compound into a twin-screw extruder (barrel temperature 160 °C). During the continuous extrusion through a die head with a diameter of 10 mm, synchronously use a wire feeding device controlled by servo to embed the sulfurized modified stainless steel wire into the colloid interior at an equal distance along the extrusion direction with an arrangement density of 3 pieces / cm 2 to obtain a silicone rubber main body;

[0066] (5) Use a winding machine to helically wrap aramid fiber (model K49, linear density 1680 dtex) on the outer surface of the silicone rubber main body at a winding angle of 55°, with a winding tension of 4.5 N and a wire guiding nozzle moving speed of 120 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0067] (6) Then perform segmented vulcanization on the silicone rubber main body with the winding fiber layer. In the first stage, the temperature is 170 °C and the time is 5 min. In the second stage, the temperature is 185 °C and the time is 12 min. In the third stage, treat at 200 °C for 20 min to obtain a silicone rubber strip.

[0068] Comparative Example 2:

[0069] The difference between Comparative Example 2 and Example 2 is that: thiourea was not added in step (2);

[0070] The specific steps are as follows:

[0071] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 10 wt%, with a liquid-solid ratio of 20:1, perform impregnation treatment for 10 min, then wash with deionized water and dry in vacuum to obtain a pretreated stainless steel wire;

[0072] (2) Add 20 g of dimethyldiallylammonium chloride to 400 g of isopropanol to obtain an adsorption solution. Immerse the pretreated stainless steel wire into the adsorption solution, with a liquid-solid ratio of 20:1, perform impregnation treatment for 4 h, and dry in vacuum to obtain a surface-treated stainless steel wire;

[0073] (3) Place the surface-treated stainless steel wire in a tubular furnace, introduce a mixed gas of H2S / N2 (volume ratio 1:9, total flow rate 200 mL / min), control the pressure inside the tube to be 0.1 MPa, heat from room temperature to 200 °C at a rate of 5 °C / min, and hold for 30 min to obtain sulfurized modified stainless steel wire;

[0074] (4) Mix 100 g of methyl vinyl silicone rubber (type 110-2), 8 g of hexamethyldisilazane, 35 g of fumed silica (specific surface area 380 m 2 / g) and 0.5 g of hydrogen-containing silicone oil (viscosity 85 at 25 °C, hydrogen content 0.5%) and stir at a speed of 200 rpm for 25 min. Then add 0.2 g of platinum catalyst and continue stirring for 15 min to obtain a rubber compound;

[0075] (5) Load the rubber compound into a twin-screw extruder (barrel temperature 160 °C). During the continuous extrusion through a die head with a diameter of 10 mm, simultaneously use a wire feeding device controlled by servo to equally embed the sulfurized modified stainless steel wire into the colloid interior at an arrangement density of 3 pieces / cm 2 along the extrusion direction to obtain a silicone rubber main body;

[0076] (6) Use a winding machine to helically wrap aramid fiber (model K49, linear density 1680 dtex) on the outer surface of the silicone rubber main body at a winding angle of 55°, with a winding tension of 4.5 N and a wire guiding nozzle moving speed of 120 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0077] (7) Then subject the silicone rubber main body with the winding fiber layer to segmented vulcanization. In the first stage, the temperature is 170 °C and the time is 5 min. In the second stage, the temperature is 185 °C and the time is 12 min. In the third stage, treat at 200 °C for 20 min to obtain a silicone rubber strip.

[0078] Comparative Example 3:

[0079] The difference between Comparative Example 3 and Example 2 is that: in step (2), dimethyldiallylammonium chloride is not added;

[0080] The specific steps are as follows:

[0081] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 10 wt%, with a liquid-solid ratio of 20:1, immerse for 10 min, then wash with deionized water and vacuum dry to obtain a pretreated stainless steel wire;

[0082] (2) Add 20 g of thiourea to 400 g of isopropanol to obtain an adsorption solution, immerse the pretreated stainless steel wire into the adsorption solution, with a liquid-solid ratio of 20:1, immerse for 4 h, and vacuum dry to obtain a surface-treated stainless steel wire;

[0083] (3) Place the surface-treated stainless steel wire in a tubular furnace, introduce a mixed gas of H2S / N2 (volume ratio 1:9, total flow rate 200 mL / min), control the pressure inside the tube to be 0.1 MPa, heat from room temperature to 200 °C at a rate of 5 °C / min, and hold for 30 min to obtain sulfurized modified stainless steel wire;

[0084] (4) Mix 100 g of methyl vinyl silicone rubber (type 110-2), 8 g of hexamethyldisilazane, 35 g of fumed silica (specific surface area 380 m 2 / g) and 0.5 g of hydrogen-containing silicone oil (viscosity 85 at 25 °C, hydrogen content 0.5%), stir at a speed of 200 rpm for 25 min, then add 0.2 g of platinum catalyst and continue stirring for 15 min to obtain a rubber compound;

[0085] (5) Load the rubber compound into a twin-screw extruder (barrel temperature 160 °C). During the continuous extrusion through a die head with a diameter of 10 mm, simultaneously use a wire feeding device controlled by servo to evenly embed the sulfurized modified stainless steel wire into the colloid along the extrusion direction at an arrangement density of 3 pieces / cm 2 to obtain a silicone rubber main body;

[0086] (6) Use a winding machine to helically wrap aramid fiber (model K49, linear density 1680 dtex) on the outer surface of the silicone rubber main body at a winding angle of 55°, with a winding tension of 4.5 N and a wire guiding nozzle moving speed of 120 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0087] (7) Then perform segmented vulcanization on the silicone rubber main body with the winding fiber layer. In the first stage, the temperature is 170 °C and the time is 5 min. In the second stage, the temperature is 185 °C and the time is 12 min. In the third stage, treat at 200 °C for 20 min to obtain a silicone rubber strip.

[0088] Comparative Example 4:

[0089] The difference between Comparative Example 4 and Example 2 is that the sulfurized modified stainless steel wire in step (5) is replaced with surface-treated stainless steel wire;

[0090] The specific steps are as follows:

[0091] (1) Immerse a stainless steel wire (type 304) with a diameter of 0.3 mm into a sulfuric acid solution with a concentration of 10 wt%, with a liquid-solid ratio of 20:1, perform impregnation treatment for 10 min, then wash with deionized water and vacuum dry to obtain a pretreated stainless steel wire;

[0092] (2) Add 12 g of thiourea and 8 g of dimethyldiallylammonium chloride to 400 g of isopropanol to obtain an adsorption solution. Immerse the pretreated stainless steel wire into the adsorption solution with a liquid-to-solid ratio of 20:1, conduct the immersion treatment for 4 h, and then conduct vacuum drying to obtain the surface-treated stainless steel wire;

[0093] (3) Mix 100 g of methyl vinyl silicone rubber (type 110-2), 8 g of hexamethyldisilazane, 35 g of fumed silica (specific surface area is 380 m 2 / g), and 0.5 g of hydrogen-containing silicone oil (viscosity at 25 °C is 85, hydrogen content is 0.5%) and stir at a speed of 200 rpm for 25 min. Then add 0.2 g of platinum catalyst and continue stirring for 15 min to obtain a rubber compound;

[0094] (4) Load the rubber compound into a twin-screw extruder (barrel temperature 160 °C). During the continuous extrusion process through a die head with a diameter of 10 mm, synchronously use a wire feeding device controlled by servo to evenly embed the surface-treated stainless steel wire into the colloid along the extrusion direction at an arrangement density of 3 pieces / cm 2 to obtain a silicone rubber main body;

[0095] (5) Use a winding machine to helically wrap aramid fiber (model K49, linear density 1680 dtex) on the outer surface of the silicone rubber main body at a winding angle of 55°, with a winding tension of 4.5 N and a wire guiding nozzle moving speed of 120 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0096] (6) Then conduct segmented vulcanization on the silicone rubber main body with the winding fiber layer. In the first stage, the temperature is 170 °C and the time is 5 min. In the second stage, the temperature is 185 °C and the time is 12 min. In the third stage, conduct treatment at 200 °C for 20 min to obtain a silicone rubber strip.

[0097] Performance test:

[0098] Tensile strength test: According to the standard of GB / T 528-2009, use a universal material testing machine, set the tensile speed to 500 mm / min, record the maximum load value when the specimen breaks, and calculate the tensile strength. The results are shown in Table 1.

[0099] Flexural strength test: According to the standard of GB / T 6035-2006, use a three-point bending test device, set the span to (60 ± 0.5) mm, the radius of the loading indenter is 5 mm, apply a bending force at a loading speed of 50 mm / min, record the maximum load when the specimen breaks, and calculate the flexural strength. The results are shown in Table 1.

[0100] Hardness test: According to the standard of GB / T 531.1-2008, use a Shore A durometer (measurement range 0-100 HA) to test. Take 5 different measurement points, with an interval of ≥6 mm between each point. Press the durometer vertically into the surface of the specimen, and read the stable value within 1 second. Take the arithmetic mean. The results are shown in Table 1.

[0101] High-temperature aging test: According to the standard of GB / T 3512-2014, place the specimen in a forced-air drying oven at 200 °C for 240 h. After taking it out, cool it to room temperature in a desiccator, and test the tensile strength retention rate and flexural strength retention rate before and after aging. The results are shown in Table 1.

[0102] Flexural fatigue test: According to the standard of GB / T 13934-2006, use an electric reciprocating bending testing machine, with a bending angle of ±45°, a frequency of 5.0 Hz, a pre-tension of 10 N, and an ambient temperature of 85 °C. After the specimen is installed, perform 500 pre-cycles first, and then conduct the formal test. Record the number of cycles at fracture. The results are shown in Table 1.

[0103] Table 1 Performance test results

[0104]

[0105]

[0106] Data analysis:

[0107] From the data of Examples 1-3 in Table 1, it can be seen that the materials prepared by the present invention show significant advantages in mechanical properties and durability. Through the introduction of sulfurized modified stainless steel wires, the materials have reached a relatively high level in terms of tensile strength, flexural strength, and fatigue performance. This may be due to the formation of a sulfide layer and active alkenyl sites during the sulfurization modification process, which improve the surface activity and interfacial bonding force of the stainless steel wires, thereby optimizing the mechanical property transfer between the stainless steel wires and the silica gel matrix. In addition, this sulfide layer may have relatively high chemical stability and resistance

[0108] From the data of Example 2 and Comparative Example 1 in Table 1, it can be seen that the application of sulfurized modified stainless steel wire in Example 2 significantly improved the comprehensive performance of the material, and its tensile strength, bending strength and the number of cycles at fracture were all better than those of Comparative Example 1. This indicates that through sulfurization modification treatment, a sulfide layer with high chemical stability and mechanical strength may be formed on the surface of the stainless steel wire, thereby enhancing the interfacial bonding force between it and the silica gel matrix. The improvement of this interfacial bonding force may effectively disperse the external stress, making the material show higher strength during the tensile and bending processes. At the same time, sulfurization modification may improve the fatigue resistance of the stainless steel wire, making it show a longer service life in the high-frequency bending fatigue test. It is thus speculated that sulfurization modification not only changes the surface chemical properties of the stainless steel wire, but may also improve the reliability of the material in a complex stress environment by optimizing the interfacial microstructure.

[0109] From the data of Example 2 and Comparative Example 2 in Table 1, it can be seen that the introduction of thiourea in Example 2 played a significant role in improving the material properties. Its tensile strength, bending strength and fatigue life were all better than those of Comparative Example 2. This may be attributed to the fact that the presence of thiourea promoted the uniform formation of the sulfide layer on the surface of the stainless steel wire, and, possibly through a restricting effect, further riveted dimethyldiallylammonium chloride on the wire surface, improving the interfacial bonding strength between the wire surface and the matrix resin.

[0110] From the data of Example 2 and Comparative Example 3 in Table 1, it can be seen that the introduction of dimethyldiallylammonium chloride in Example 2 played an important role in improving the comprehensive performance of the material. Its tensile strength, bending strength and fatigue life were all better than those of Comparative Example 3. This may be because dimethyldiallylammonium chloride has good surface activity in the adsorption solution, and the cationic group in its molecular structure can form a stable adsorption layer with the surface of the stainless steel wire, thus providing a more uniform reaction interface for the subsequent sulfidation reaction.

[0111] From the data of Example 2 and Comparative Example 4 in Table 1, it can be seen that the application of sulfurized modified stainless steel wire in Example 2 had a significant effect on improving the material properties. Its tensile strength, bending strength and fatigue life were all better than those of Comparative Example 4. This may be because the sulfur element in the sulfide layer may form a chemical bridge with the active groups in the silicone rubber through diffusion. This chemical bonding may be more resistant to fatigue stress than simple physical bonding. At the same time, the sulfidation treatment may eliminate the microscopic defects on the wire surface, form a nanoscale rough structure, and enhance the mechanical anchoring effect.

[0112] Those of ordinary skill in the art should understand that any discussion of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A high hardness silicone strip, characterized in that: It comprises a silica gel body, sulfur-impregnated stainless steel wires and a winding fiber layer; the inside of the silica gel body is equidistantly distributed with sulfur-impregnated stainless steel wires at a density of 3-5 per square centimeter along the axial direction; the winding fiber layer is a spirally wrapped aramid fiber on the outer surface of the silica gel body; The preparation steps of the sulfurized modified stainless steel wire are as follows: (1) immersing the stainless steel wire in a sulfuric acid solution, immersing the wire, washing the wire with water, and drying the wire to obtain a pretreated stainless steel wire; (2) adding thiourea and dimethyldiallyl ammonium chloride to isopropanol to obtain an adsorption solution, immersing the pretreated stainless steel wire into the adsorption solution, performing immersion treatment, and vacuum drying to obtain a surface-treated stainless steel wire; (3) placing the surface treated stainless steel wire in a tubular furnace for sulfurizing treatment to obtain sulfurized modified stainless steel wire; In the step (2), the weight ratio of thiourea, dimethyldiallylammonium chloride and isopropanol is 10-15:5-10:300-500; The liquid-to-solid ratio of the immersion treatment in step (2) is 15-25:1, and the time is 3-5 hours; The atmosphere for the sulfurization treatment in step (3) is a H2S / N2 mixed gas with a volume ratio of 1:8-10, a flow rate of 180-220 mL / min, an inner tube pressure of 0.09-0.11 MPa, and the temperature is raised from room temperature to 195-205°C at a rate of 3-10°C / min and kept warm for 20-40 min.

2. The high hardness silicone strip according to claim 1, characterized in that: The silica gel body is prepared from the following raw materials by weight: 80-120 parts of methyl vinyl silicone rubber, 6-10 parts of hexamethyldisilazane, 30-40 parts of fumed silica, 0.3-1 parts of hydrogen-containing silicone oil and 0.1-0.3 parts of platinum catalyst.

3. The high hardness silicone strip according to claim 2, characterized in that: The model of the methyl vinyl silicone rubber is 110-2, and the specific surface area of ​​the fumed silica is 300-400m 2 / g, the viscosity of hydrogen-containing silicone oil is 80-90 at 25°C, and the hydrogen content is 0.3%-0.8%.

4. The high hardness silicone strip according to claim 1, characterized in that: The thickness of the winding fiber layer is 0.2-0.3 mm.

5. The high hardness silicone strip according to claim 1, characterized in that: The concentration of the sulfuric acid solution in step (1) is 8wt%-12wt%.

6. The high-hardness silicone strip according to claim 1, characterized in that: The liquid-to-solid ratio of the immersion treatment in step (1) is 15-25:1, and the time is 8-12 minutes.

7. The high-hardness silicone strip according to claim 1, characterized in that: The diameter of the stainless steel wire in step (1) is 0.2-0.5 mm.

8. A method for preparing a high-hardness silicone strip according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Mix methyl vinyl silicone rubber, hexamethyldisilazane, fumed silica and hydrogenated silicone oil, stir at a speed of 150-250 rpm for 20-30 min, add platinum catalyst, and continue stirring for 10-20 min to obtain a rubber compound; S2: The rubber material is loaded into a twin-screw extruder with a barrel temperature of 155-165°C. During continuous extrusion through a die head with a diameter of 8-12 mm, a servo-controlled wire feeding device is simultaneously used to embed the sulfur-modified stainless steel wire into the colloid at equal distances along the extrusion direction to obtain a silicone body; S3: A winding machine is used to spirally wrap aramid fibers on the outer surface of the silicone body at a winding angle of 50-60°, the winding tension is 4-5N, and the wire guide nozzle moving speed is 110-130mm / s to form a winding fiber layer; S4: The silicone body containing the winding fiber layer is vulcanized in stages. In the first stage, the temperature is 165-175°C for 4-6 minutes. In the second stage, the temperature is 180-190°C for 10-14 minutes. In the third stage, the temperature is 195-205°C for 15-25 minutes to obtain a high-hardness silicone strip.

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