A high-hardness silica gel strip and a preparation method thereof

Abstract

The present application 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 body, sulfurized modified stainless steel wires and a winding fiber layer. The silica gel body is prepared from raw materials such as methyl vinyl silicone rubber and fumed white carbon black, and the stainless steel wires are embedded in the silica gel body. The winding fiber layer is formed by spirally wrapping aramid fibers on the surface of the silica gel body. Through the synergistic effect of the sulfurized modified stainless steel wires and the winding fiber layer, the silica gel strip exhibits excellent tensile strength, bending strength and fatigue life, and can be widely applied in the fields of photovoltaic modules, aerospace, automobile manufacturing and the like, thereby significantly prolonging the service life and reducing the maintenance cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber, in particular to a high-hardness silica gel strip and a preparation method thereof. BACKGROUND

[0002] As an important elastomer material, silica gel strips are widely used in photovoltaic module manufacturing, aerospace, automobile manufacturing, electronic device protection and other fields due to their excellent high and low temperature resistance, chemical stability and good elasticity. However, with the complication of application scenarios, traditional silica gel strips have exposed some problems in actual use, especially in high-strength stretching, bending or complex stress environment, which are prone to deformation, fracture or delamination, seriously affecting their service life and reliability.

[0003] At present, the research on improving the performance of silica gel strips mainly focuses on the following aspects: one is to improve the mechanical properties of the silica rubber matrix, such as introducing nano fillers, reinforcing fibers or chemical crosslinking agents to improve the strength and toughness of the silica rubber; the other is to embed metal wires or fiber layers in the silica gel strip to enhance its structural stability. However, these methods still have certain limitations in actual application. For example, although embedding metal wires can significantly improve the tensile strength of the silica gel strip, due to the weak interfacial bonding force between the metal wires and the silica rubber matrix, it is easy to cause interfacial delamination or stress concentration, thereby reducing the overall performance of the composite material. In addition, although the traditional metal wire surface treatment methods (such as pickling, phosphating, etc.) can improve the interfacial bonding force to a certain extent, their effect is limited and difficult to meet the high performance requirements in complex stress environment. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a high-hardness silica gel strip and a preparation method thereof to improve the mechanical properties and structural stability of the silica gel strip and meet the needs of complex stress environment.

[0005] In order to achieve the above purpose, the present application provides a high-hardness silica gel strip, which comprises a silica gel body, a sulfur-modified stainless steel wire and a winding fiber layer.

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

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

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

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

[0010] Further, the inside of the silica gel body is equidistantly distributed with 3-5 sulfur-modified stainless steel wires per square centimeter.

[0011] Further, the winding fiber layer is spirally wrapped by aramid fibers on the outer surface of the silica gel body.

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

[0013] Further, the preparation steps of the sulfur-modified stainless steel wire are as follows:

[0014] (1) immerse the stainless steel wire into a sulfuric acid solution, perform immersion treatment, wash with water, dry, and obtain a pretreated stainless steel wire;

[0015] (2) add thiourea and dimethyldiallylammonium chloride into isopropyl alcohol to obtain an adsorption solution, immerse the pretreated stainless steel wire into the adsorption solution, perform immersion treatment, and vacuum dry to obtain a surface-treated stainless steel wire;

[0016] (3) place the surface-treated stainless steel wire into a tube furnace, perform sulfurization treatment, and obtain a sulfur-modified stainless steel wire.

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

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

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

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

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

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

[0023] Further, the application also provides a preparation method of the high-hardness silica gel strip.

[0024] S1: mixing methyl vinyl silicone rubber, hexamethyl disilazane, fumed white carbon black and hydrogen-containing silicone oil, stirring at a speed of 150-250 rpm for 20-30 min, then adding platinum catalyst and continuing to stir for 10-20 min to obtain a rubber compound;

[0025] S2: loading the rubber compound into a double screw extruder, setting the barrel temperature at 155-165 DEG C, and continuously extruding through a die with a diameter of 8-12 mm, simultaneously using a servo-controlled wire feeding device to embed sulfur-modified stainless steel wires into the rubber compound at equal intervals along the extrusion direction to obtain a silica gel body;

[0026] S3: using a winding machine to spiral wrap aramid fibers on the outer surface of the silica gel body at a winding angle of 50-60 DEG, the winding tension is 4-5 N, and the moving speed of the wire guide is 110-130 mm / s to form a wrapped fiber layer;

[0027] S4: segmenting the silica gel body with the wrapped fiber layer for vulcanization, in the first stage, the temperature is 165-175 DEG C and the time is 4-6 min, in the second stage, the temperature is 180-190 DEG C and the time is 10-14 min, and in the third stage, the temperature is 195-205 DEG C and the time is 15-25 min to obtain a high-hardness silica gel strip.

[0028] The application has the following advantages:

[0029] The application embeds the stainless steel wire by sulfur infiltration treatment, which enhances the silica gel strip in high hardness, and enables the silica gel strip to bend without breaking to a certain extent, so as to meet the requirements of different installation environments, such as maintaining good performance when applying pressure in a narrow space without being crushed.

[0030] The application improves the structural stability of the silica gel strip by the combined action of the sulfur-treated stainless steel wire and the wrapped fiber layer, which can effectively disperse stress and prevent the silica gel strip from deforming, breaking or delaminating when subjected to external large pressure, tension or impact force, thereby prolonging the service life of the silica gel strip and reducing the maintenance cost.

[0031] The present application forms a dense and uniform sulfide layer on the surface of the stainless steel wire through sulfur modification, which 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 transmission of mechanical properties, but also significantly improves the reliability of the composite material in complex stress environment. In addition, the sulfide layer formed during the sulfur modification process can react with the active groups in the silicone rubber matrix through chemical bonding, further improving the chemical bonding strength of the interface. At the same time, the nanoscale 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 tensile, bending and fatigue.

[0032] The present application also further optimizes the chemical properties of the surface of the stainless steel wire by adding thiourea and dimethyldiallylammonium chloride in the adsorption solution. 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 group, providing a more uniform reaction interface for the subsequent sulfuration reaction. This synergistic effect significantly improves the interfacial activity of the surface of the stainless steel wire, 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 application shows excellent performance in terms of tensile strength, bending strength and fatigue life, and can be widely used in fields with high protection performance requirements such as photovoltaic module manufacturing, aerospace, automobile manufacturing, electronic equipment protection, etc. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below with specific examples.

[0035] Example 1:

[0036] (1) The stainless steel wire (type 304) with a diameter of 0.3 mm was immersed in a sulfuric acid solution with a concentration of 8wt%, the liquid-solid ratio was 15:1, and the immersion treatment time was 12 min. Then it was washed with deionized water and vacuum dried to obtain the pretreated stainless steel wire;

[0037] (2) 10g of thiourea and 5g of dimethyldiallylammonium chloride were added to 300g of isopropyl alcohol to obtain an adsorption solution. The pretreated stainless steel wire was immersed in the adsorption solution, the liquid-solid ratio was 15:1, and the immersion treatment time was 3h. Then it was vacuum dried to obtain the surface-treated stainless steel wire;

[0038] (3) The surface-treated stainless steel wire was placed in a tube furnace, and H2S / N2 mixed gas (volume ratio of 1:8, total flow rate of 180 mL / min) was introduced, the pressure in the tube was controlled at 0.09 MPa, and the temperature was increased from room temperature to 195°C at a rate of 3°C / min, and then kept for 20 min to obtain sulfurized modified stainless steel wire;

[0039] (4) 80 g of methylvinyl silicone rubber (type 110-2), 6 g of hexamethyldisilazane, 30 g of fumed white carbon black (specific surface area of 380 m 2 / g) and 0.3 g of hydrogen-containing silicone oil (viscosity of 85 at 25°C, hydrogen content of 0.5%) were mixed, stirred at a speed of 150 rpm for 20 min, then 0.1 g of platinum catalyst was added, and the stirring was continued for 10 min to obtain a rubber compound;

[0040] (5) The rubber compound was loaded into a twin-screw extruder (barrel temperature of 155°C), and during the continuous extrusion process through a 10 mm diameter die, a servo-controlled wire feeding device was used to embed sulfurized modified stainless steel wire into the rubber compound at a spacing density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0041] (6) Using a winding machine, aramid fiber (type K49, linear density of 1680 dtex) was spirally wrapped around the outer surface of the silicone rubber body at a wrapping angle of 55°, the wrapping tension was 4 N, and the wire guide moving speed was 110 mm / s to form a wrapped fiber layer with a thickness of 0.25 mm;

[0042] (7) The silicone rubber body with the wrapped fiber layer was then subjected to segmented vulcanization, the first stage was at a temperature of 165°C for 6 min, the second stage was at a temperature of 180°C for 14 min, and the third stage was at a temperature of 195°C for 25 min to obtain a high-hardness silicone rubber strip.

[0043] Example 2:

[0044] (1) The stainless steel wire (type 304) with a diameter of 0.3 mm was immersed in a 10 wt% sulfuric acid solution, the liquid-solid ratio was 20:1, and the immersion treatment time was 10 min, then it was washed with deionized water and vacuum dried to obtain a pretreated stainless steel wire;

[0045] (2) 12 g of thiourea and 8 g of dimethyldiallylammonium chloride were added to 400 g of isopropyl alcohol to obtain an adsorption solution, the pretreated stainless steel wire was immersed in the adsorption solution, the liquid-solid ratio was 20:1, and the immersion treatment time was 4 h, then it was vacuum dried to obtain a surface-treated stainless steel wire;

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

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

[0048] (5) Put the rubber compound into a twin-screw extruder (barrel temperature of 160°C), and during the continuous extrusion process through a die with a diameter of 10 mm, use a servo-controlled wire feeding device to embed sulfurized modified stainless steel wire into the rubber compound at a spacing density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0049] (6) Use a winding machine to spiral wrap aramid fiber (type 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 4.5 N and a godet moving speed of 120 mm / s to form a wound fiber layer with a thickness of 0.25 mm;

[0050] (7) Further segmentally vulcanize the silicone rubber body containing the wound fiber layer, with the first stage at a temperature of 170°C for 5 min, the second stage at a temperature of 185°C for 12 min, and the third stage at a temperature of 200°C for 20 min to obtain a high-hardness silicone rubber strip.

[0051] Example 3:

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

[0053] (2) Add 15 g of thiourea and 10 g of dimethyldiallylammonium chloride to 500 g of isopropyl alcohol to obtain an adsorption solution, and immerse the pretreated stainless steel wire in the adsorption solution with a liquid-solid ratio of 25:1 for 5 h, and vacuum dry to obtain surface-treated stainless steel wire;

[0054] (3) The surface-treated stainless steel wire was placed in a tube furnace, and H2S / N2 mixed gas (volume ratio of 1:10, total flow rate of 220 mL / min) was introduced, the pressure in the tube was controlled at 0.11 MPa, and the temperature was increased from room temperature to 205°C at a rate of 10°C / min, and kept for 40 min to obtain sulfurized modified stainless steel wire;

[0055] (4) 120 g of methylvinyl silicone rubber (type 110-2), 10 g of hexamethyldisilazane, 40 g of fumed white carbon black (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%) were mixed, stirred at a speed of 250 rpm for 30 min, then 0.3 g of platinum catalyst was added, and the stirring was continued for 20 min to obtain a rubber compound;

[0056] (5) The rubber compound was loaded into a twin-screw extruder (barrel temperature of 165°C), and during the continuous extrusion process through a 10 mm diameter die, a servo-controlled wire feeding device was used to embed sulfurized modified stainless steel wire into the rubber compound at a spacing density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0057] (6) Aramid fiber (type K49, linear density of 1680 dtex) was spirally wrapped around the outer surface of the silicone rubber body at a wrapping angle of 55° using a winding machine, the wrapping tension was 5 N, and the godet moving speed was 130 mm / s to form a wrapped fiber layer with a thickness of 0.25 mm;

[0058] (7) The silicone rubber body with the wrapped fiber layer was then subjected to segmented vulcanization, the first stage was at a temperature of 175°C for 4 min, the second stage was at a temperature of 190°C for 10 min, and the third stage was at a temperature of 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 by pretreated stainless steel wire;

[0061] The specific steps are as follows:

[0062] (1) The stainless steel wire (type 304) with a diameter of 0.3 mm was immersed in a sulfuric acid solution with a concentration of 10 wt%, the liquid-solid ratio was 20:1, and the immersion treatment time was 10 min, then it was washed with deionized water and vacuum dried to obtain pretreated stainless steel wire;

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

[0064] (3) Mix 100 g of methylvinyl silicone rubber (type 110-2), 8 g of hexamethyldisilazane, 35 g of fumed white carbon black (specific surface area of 380 m 2 / g) and 0.5 g of hydrogen-containing silicone oil (viscosity of 85 at 25 ℃, hydrogen content of 0.5%) to obtain a rubber compound, and stir at a speed of 200 rpm for 25 min, then add 0.2 g of platinum catalyst and continue to stir for 15 min to obtain a rubber compound;

[0065] (4) Put the rubber compound into a twin-screw extruder (barrel temperature of 160 ℃), and continuously extrude through a 10 mm diameter die, and simultaneously use a servo-controlled wire feeding device to embed sulfurized modified stainless steel wire into the rubber compound at a spacing density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0066] (5) Use a winding machine to spiral wrap aramid fiber (type 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 4.5 N and a godet moving speed of 120 mm / s to form a winding fiber layer with a thickness of 0.25 mm;

[0067] (6) Segmentally vulcanize the silicone rubber body with the winding fiber layer, the first stage is at a temperature of 170 ℃ for 5 min, the second stage is at a temperature of 185 ℃ for 12 min, and the third stage is at a temperature of 200 ℃ 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 no thiourea is added in step (2);

[0070] The specific steps are as follows:

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

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

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

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

[0075] (5) Put the rubber compound into a twin-screw extruder (barrel temperature of 160°C), and continuously extrude through a 10 mm diameter die, while synchronously using a servo-controlled wire feeding device to embed sulfurized modified stainless steel wire into the rubber compound at a spacing density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0076] (6) Use a winding machine to spiral wrap aramid fiber (type 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 4.5 N and a godet moving speed of 120 mm / s to form a wound fiber layer with a thickness of 0.25 mm;

[0077] (7) Segmentally vulcanize the silicone rubber body with the wound fiber layer, with the first stage at a temperature of 170°C for 5 min, the second stage at a temperature of 185°C for 12 min, and the third stage at a temperature of 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 no dimethyl diallyl ammonium chloride is added in step (2);

[0080] The specific steps are as follows:

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

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

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

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

[0085] (5) Put the rubber compound into a twin-screw extruder (barrel temperature of 160°C), and during the continuous extrusion process through a die with a diameter of 10 mm, use a servo-controlled wire feeding device to embed sulfur-modified stainless steel wire into the rubber compound at a spacing density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0086] (6) Use a winding machine to spiral wrap aramid fiber (type 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 4.5 N and a godet moving speed of 120 mm / s to form a wrapped fiber layer with a thickness of 0.25 mm;

[0087] (7) Segmentally vulcanize the silicone rubber body containing the wrapped fiber layer, with the first stage at a temperature of 170°C for 5 min, the second stage at a temperature of 185°C for 12 min, and the third stage at a temperature of 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 sulfur-modified stainless steel wire in step (5) is replaced by surface-treated stainless steel wire;

[0090] The specific steps are as follows:

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

[0092] (2) 12 g thiourea and 8 g dimethyldiallyl ammonium chloride were added into 400 g isopropyl alcohol to obtain an adsorption solution, and the pretreated stainless steel wire was immersed in the adsorption solution with a liquid-to-solid ratio of 20:1 for 4 h, and then vacuum dried to obtain the surface-treated stainless steel wire;

[0093] (3) 100 g methyl vinyl silicone rubber (type 110-2), 8 g hexamethyldisilazane, 35 g fumed white carbon black (specific surface area of 380 m 2 / g), and 0.5 g hydrogen-containing silicone oil (viscosity of 85 at 25 °C and hydrogen content of 0.5%) were mixed, stirred at a speed of 200 rpm for 25 min, and then 0.2 g of platinum catalyst was added and stirred for another 15 min to obtain a rubber compound;

[0094] (4) The rubber compound was loaded into a twin-screw extruder (barrel temperature of 160 °C), and during the continuous extrusion process through a 10 mm diameter die, a servo-controlled wire feeding device was used to embed the surface-treated stainless steel wire into the rubber compound at an arrangement density of 3 roots / cm 2 in the extrusion direction to obtain a silicone rubber body;

[0095] (5) An aramid fiber (type K49, linear density of 1680 dtex) was spirally wrapped around the outer surface of the silicone rubber body at a wrapping angle of 55° using a winding machine, with a winding tension of 4.5 N and a godet moving speed of 120 mm / s to form a wrapped fiber layer with a thickness of 0.25 mm;

[0096] (6) The silicone rubber body with the wrapped fiber layer was then subjected to segmented vulcanization, with the first stage at a temperature of 170 °C for 5 min, the second stage at a temperature of 185 °C for 12 min, and the third stage at a temperature of 200 °C for 20 min to obtain a silicone rubber strip.

[0097] Performance test:

[0098] Tensile strength test: According to GB / T 528-2009 standard, a universal material testing machine was used with a tensile speed of 500 mm / min, and the maximum load value at the breaking of the sample was recorded to calculate the tensile strength, and the results are shown in Table 1.

[0099] Bending strength test: According to GB / T 6035-2006 standard, a three-point bending test device was used with a span setting of (60 ± 0.5) mm, a loading pressure head radius of 5 mm, and a loading speed of 50 mm / min to apply bending force, and the maximum load at the breaking of the sample was recorded to calculate the bending strength, and the results are shown in Table 1.

[0100] Hardness test: According to GB / T 531.1-2008 standard, using Shore A hardness tester (measurement range 0-100 HA) to test, taking 5 different measuring points, each point interval ≥ 6 mm, the hardness tester is vertically pressed into the sample surface, the stable value is read within 1 second, the arithmetic mean value is taken, and the results are shown in Table 1.

[0101] High temperature aging test: According to GB / T 3512-2014 standard, the sample is placed in a 200℃ air drying oven for 240h, and then cooled to room temperature in a desiccator. The tensile strength retention rate and bending strength retention rate before and after aging are tested, and the results are shown in Table 1.

[0102] Bending fatigue test: According to GB / T 13934-2006 standard, using an electric reciprocating bending tester, the bending angle is ±45°, the frequency is 5.0Hz, the pre-tension is 10N, the environmental temperature is 85℃, the sample is installed and then pre-circulated for 500 times, and then formally tested. The cycle number at the time of fracture is recorded, and 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 material prepared by the application has shown significant advantages in mechanical properties and durability. Through the introduction of sulfur-modified stainless steel wire, the material has reached a high level in tensile strength, bending strength and fatigue performance, etc. This may be due to the sulfide layer and active alkenyl sites formed during the sulfur modification process, which improves the surface activity and interfacial bonding force of the stainless steel wire, thereby optimizing the mechanical property transmission between the stainless steel wire and the silica gel matrix. In addition, the sulfide layer may have high chemical stability and anti

[0108] As can be seen from the data of Example 2 and Comparative Example 1 in Table 1, the application of sulfurized modified stainless steel wire in Example 2 significantly improves the overall performance of the material, with higher tensile strength, bending strength, and cycle number at break than Comparative Example 1. This indicates that through sulfurization modification treatment, a sulfide layer with high chemical stability and mechanical strength may be generated on the surface of the stainless steel wire, thereby enhancing the interfacial bonding force with the silica gel matrix. This improvement in interfacial bonding force can effectively disperse external stress, making the material exhibit higher strength during tensile and bending processes. At the same time, sulfurization modification can improve the fatigue resistance of the stainless steel wire, making it exhibit longer service life in high-frequency bending fatigue tests. It is inferred that sulfurization modification not only changes the surface chemical properties of the stainless steel wire, but also may improve the reliability of the material under complex stress environment by optimizing the interfacial microstructure.

[0109] As can be seen from the data of Example 2 and Comparative Example 2 in Table 1, the introduction of thiourea in Example 2 has a significant effect on the improvement of material performance, with higher tensile strength, bending strength, and fatigue life than Comparative Example 2. This may be due to the presence of thiourea promoting the uniform formation of the sulfide layer on the surface of the stainless steel wire, and possibly further limiting the dimethyldiallylammonium chloride rivets on the surface of the steel wire, improving the interfacial bonding strength between the steel wire surface and the matrix resin.

[0110] As can be seen from the data of Example 2 and Comparative Example 3 in Table 1, the introduction of dimethyldiallylammonium chloride in Example 2 plays an important role in improving the overall performance of the material, with higher tensile strength, bending strength, and fatigue life than Comparative Example 3. This may be because dimethyldiallylammonium chloride has good surface activity in the adsorption liquid, and the cationic group in its molecular structure can form a stable adsorption layer on the surface of the stainless steel wire, thereby providing a more uniform reaction interface for subsequent sulfidation reactions.

[0111] As can be seen from the data of Example 2 and Comparative Example 4 in Table 1, the application of sulfurized modified stainless steel wire in Example 2 has a significant effect on the improvement of material performance, with higher tensile strength, bending strength, and fatigue life than Comparative Example 4. This may be due to the fact that the sulfur element in the sulfide layer may form a chemical bridge with the active groups in the silicone rubber through diffusion, and this chemical bonding may be more resistant to fatigue stress than simple physical bonding. At the same time, sulfurization treatment can eliminate micro defects on the surface of the steel wire and form a nanoscale rough structure, enhancing the mechanical anchoring effect.

[0112] Those skilled in the art should understand that the above discussion of any embodiment is only intended to be exemplary in nature and is not intended to suggest that the present application is limited to these examples; under the concept of the present application, the above embodiments or technical features among different embodiments can be combined, steps can be implemented in any order, and there are many other variations of different aspects of the present application as described above, which are not provided in details for the sake of brevity.

Claims

1. A high-hardness silicone strip, characterized in that, It includes a silicone body, sulfur-modified stainless steel wires, and a wound fiber layer; the sulfur-modified stainless steel wires are evenly distributed along the axial direction inside the silicone body at a density of 3-5 wires per square centimeter; the wound fiber layer is made of aramid fibers spirally wrapped around the outer surface of the silicone body. The preparation steps of the sulfur-modified stainless steel wire are as follows: (1) Immerse the stainless steel wire in sulfuric acid solution, perform immersion treatment, wash with water, and dry to obtain pretreated stainless steel wire; (2) Thiourea and dimethyl diallyl ammonium chloride are added to isopropanol to obtain an adsorption solution. The pretreated stainless steel wire is immersed in the adsorption solution for immersion treatment and vacuum drying to obtain a surface-treated stainless steel wire. (3) Place the surface-treated stainless steel wire in a tube furnace and perform sulfur diffusion treatment to obtain sulfur-modified stainless steel wire. In step (2), the weight ratio of thiourea, dimethyl diallyl ammonium 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. In step (3), the atmosphere for sulfur diffusion treatment is a mixture of H2S / N2 gas with a volume ratio of 1:8-10, a flow rate of 180-220 mL / min, and a pipe pressure of 0.09-0.11 MPa. The temperature is increased from room temperature to 195-205℃ at a rate of 3-10℃ / min and held for 20-40 min.

2. The high-hardness silicone strip according to claim 1, characterized in that, The silicone matrix is ​​prepared from the following raw materials in parts 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 methyl vinyl silicone rubber is of type 110-2, and the fumed silica has a specific surface area of ​​300-400 m². 2 / g, the viscosity of the hydrogen-containing silicone oil at 25℃ is 80-90, 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 wound 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 1-7, characterized in that, Includes the following steps: S1: Mix methyl vinyl silicone rubber, hexamethyldisilazane, fumed silica and hydrogen-containing silicone oil, stir at 150-250 rpm for 20-30 min, then add platinum catalyst and continue stirring for 10-20 min to obtain the rubber compound; S2: The rubber compound is loaded into a twin-screw extruder with a barrel temperature of 155-165℃. During the continuous extrusion process through a die with a diameter of 8-12mm, a servo-controlled wire feeding device is used to embed sulfur-modified stainless steel wires into the compound at equal intervals along the extrusion direction to obtain the silicone body. S3: A aramid fiber is spirally wrapped on the outer surface of the silicone body with a 50-60° winding angle using a winding machine. The winding tension is 4-5N, and the guide nozzle moves at a speed of 110-130mm / s to form a wound fiber layer. S4: The silicone body containing the wound fiber layer is vulcanized in stages. The first stage is at a temperature of 165-175℃ for 4-6 minutes. The second stage is at a temperature of 180-190℃ for 10-14 minutes. The third stage is at a temperature of 195-205℃ for 15-25 minutes to obtain a high-hardness silicone strip.

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