Insulating material for isolating and protecting circuit and preparation method thereof

Abstract

The invention relates to the field of circuit element protection materials, in particular to an insulating material for isolating and protecting a circuit and a preparation method thereof.According to the insulating material, natural rubber and butadiene styrene rubber serve as main bodies, a certain amount of oil-extended butadiene styrene rubber is added, cellulose acetate fiber serves as a reinforcing material, good mechanical performance is provided, and meanwhile, the insulating material can be used for isolating and protecting the circuit; and the safety performance of the circuit equipment can be improved due to the good heat dissipation performance.

Description

Technical Field

[0001] The present application relates to the field of circuit element protection materials, and in particular to an insulating material for isolating and protecting circuits and a preparation method thereof. Background Art

[0002] Among circuit protection materials, polymer system is an important material, which is often used in the physical protection of circuit materials. Among them, the internal mixing rubber system with natural rubber / styrene butadiene rubber as the main body has good softness and strength, and low cost, and is widely used in optical cable protection, elastic support and other aspects.

[0003] Since a lot of heat is generated in the circuit system, the natural rubber / styrene-butadiene rubber system has high requirements for heat dissipation and flame retardancy. At the same time, in order to ensure insulation, materials with good thermal conductivity such as metal and graphite cannot be added to the system. At present, there are some components with aluminum oxide or aluminum hydroxide as fillers. Although they can achieve good flame retardancy, their thermal conductivity is relatively general, and their strength is poor. Their folding resistance and flexibility are insufficient. Summary of the invention

[0004] In order to achieve good flame retardancy and thermal conductivity while providing good flexibility and folding resistance, the present application provides an insulating material for isolating and protecting circuits and a preparation method thereof.

[0005] First, the present application provides an insulating material for isolating and protecting a circuit, which comprises the following components in parts by mass:

[0006]

[0007]

[0008] Wherein, the total mass parts of the aluminum hydroxide powder filler and the silicon nitride powder filler is not higher than 30 parts.

[0009] In the above technical scheme, silicon nitride ceramic powder is used as part of the filler, and alumina ceramic powder is used as the other part. Both have good insulation properties, so that the overall material will not conduct electricity. In addition, the silicon nitride ceramic powder greatly improves the thermal conductivity of the system after addition, and can make the material have good thermal conductivity when combined with silicone rubber. In addition, since silicon nitride ceramic powder introduces additional rigidity into the system, in this scheme, SBR-1500 series styrene butadiene rubber and SBR-1700 series styrene butadiene rubber are mixed to obtain an overall vulcanized rubber system. In this system, SBR-1700 series styrene butadiene rubber is an oil-filled rubber system, so its plasticity is better, and its wrapping performance for silicon nitride ceramics is better during processing, and the overall system formed is softer.

[0010] In a further preferred embodiment, the mass ratio of the alumina ceramic powder filler to the silicon nitride powder filler is 1:0.8-2. In the above embodiment, the thermal conductivity and strength can be better balanced, and the addition of a small amount of alumina ceramic powder can significantly reduce the cost without significantly reducing the thermal conductivity. At the same time, a certain amount of cellulose acetate is added to the above system as a reinforcing material. The cellulose acetate weakens the reaction performance of cellulose by modifying the cellulose fiber with acetic acid, and at the same time improves the softness of the cellulose itself. The softness of cellulose acetate can be improved.

[0011] Preferably, the acetate fibers include acetate filaments and acetate staple fibers, the aspect ratio of the acetate filaments is 500-1000, the aspect ratio of the acetate staple fibers is 50-100, and the mass ratio of the acetate filaments to the acetate staple fibers is 1.5-5:1.

[0012] Acetate fiber under the above conditions has better supporting performance. The long fiber and short fiber mixture are selected. The long fiber can improve the overall toughness, while the short fiber can form a better local strength system in the system and improve the softness, so that the material has better folding and rubbing resistance.

[0013] Preferably, it further comprises silicone rubber or fluorosilicone rubber, wherein the mass proportion of the silicone rubber or fluorosilicone rubber is 15 to 25 parts.

[0014] On the basis of the above, silicone rubber and fluorosilicone rubber have good thermal conductivity and heat resistance, and have better coating properties for silicon nitride ceramics and alumina, and have good mechanical properties, and can be well compatible in the organic system in the above system. Among them, considering the factors of price and performance itself, methylphenyl silicone rubber is preferred. The use of simple fatty alkane silicone rubber will cause the system to be too dense on the one hand, affecting its flexibility, and on the other hand, the strength is also low. Methylphenyl silicone rubber has similar performance to fluorosilane, does not contain fluorine, has a lower price and better safety. Further preferably, the methylphenyl silicone rubber uses terminal hydroxyl methylphenyl silicone rubber, which can participate in the reaction during the vulcanization process by utilizing the terminal hydroxyl group to form a better cohesive force system, which can better improve the strength of the system without increasing the hardness.

[0015] Further preferably, the molar content of phenyl in the methylphenyl silicone rubber is 30-40%. The methylphenyl silicone rubber with a higher phenyl content is not easy to crystallize, has better amorphous properties, and is easy to form an amorphous phase in the system, making the system more flexible. It should be noted that the molar content of phenyl here refers to the molar content of phenyl relative to silicon atoms.

[0016] Preferably, it also includes 2 to 4 parts by weight of ethylene-acrylate polymers. Acrylate polymers specifically refer to aliphatic substituted or unsubstituted acrylic acid ester compounds, which can be polymethyl acrylate, polymethyl methacrylate, polyethyl acrylate, polyethyl methacrylate, polybutyl acrylate, polybutyl methacrylate or other similar structural materials. Using a small amount of acrylic acid ester compounds can improve the flexibility of the system, and at the same time, the heat resistance is also good, and the overall toughness is also improved. Preferably, after experiments, the density range of the ethylene-acrylate is 1.16 to 1.21 g / cm 3 , its overall tensile strength and resilience are better.

[0017] In addition, the present application also relates to a method for preparing an insulating material for isolating and protecting a circuit, comprising the following steps:

[0018] S1. Mix the other components except sulfur and accelerator for 1 to 2 minutes at a temperature of 100 to 120°C.

[0019] S2. Add sulfur and accelerator, raise the temperature to 130-140°C, mix for 60-90s, and discharge the material. The discharge temperature is 130-150°C.

[0020] In summary, the present application provides an insulating material for isolating and protecting circuits with good heat dissipation performance and good mechanical properties. It is based on natural rubber and styrene-butadiene rubber, adds a certain amount of oil-filled styrene-butadiene rubber, and uses acetate fiber as a reinforcing material. While providing good mechanical properties, it also obtains good thermal conductivity. Its good heat dissipation can improve the safety performance of circuit equipment.

[0021] In addition, in the present application, silicone rubber, preferably terminal hydroxymethylphenyl silicone rubber, is added to significantly improve the mechanical properties of the system on the basis of the above, providing good tensile strength and elongation at break. DETAILED DESCRIPTION

[0022] The scheme in this application is further explained through the following specific implementation methods.

[0023] In the following specific implementation, the performance of the product is further tested by the following scheme:

[0024] 1. Strength test: Refer to GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber to determine the tensile strength and elongation at break of the system.

[0025] 2. Thermal conductivity: measured by thermal conductivity meter.

[0026] 3. Rebound resilience test: refer to "ASTM-F36" for measurement.

[0027] For the following examples, the preparation method is as follows:

[0028] S1. Mix the components except sulfur and accelerator for 100 seconds at a temperature of 100-120°C.

[0029] S2. Add sulfur and accelerator, raise the temperature to 130-140°C, mix for 60-90s, and discharge the material. The discharge temperature is 130-150°C.

[0030] Embodiment 1, in this embodiment, the influence of the ratio of SBR-1500 series styrene butadiene rubber and SBR-1700 series styrene butadiene rubber in the system on the performance is mainly studied, and the ratio of the mass parts of silicon nitride ceramic powder filler and alumina ceramic powder filler under different ratios of SBR-1500 series styrene butadiene rubber and SBR-1700 series styrene butadiene rubber is studied. In this embodiment, the mass parts of other components are as follows:

[0031] Natural rubber 100 parts

[0032] Acetate fiber, specifically comprising acetate filaments and acetate staple fibers, wherein the average diameters of the acetate filaments and the acetate staple fibers are both about 12 μm, the average length of the acetate filaments is 8.3±1 mm, the average length of the acetate staple fibers is 770±100 μm, the weight of the acetate filaments is 5 parts, and the weight of the acetate staple fibers is 2.5 parts;

[0033]

[0034]

[0035] The silicone rubber is a hydroxy-terminated methylphenyl silicone rubber, with a viscosity of 10000±1000 mPa·s at 25°C, a phenyl molar content of 31%, a vulcanization accelerator CZ, and an organic phosphorus flame retardant of tri-o-cresyl phosphate. The polyacrylate polymer is specifically selected from polymethyl methacrylate polymer 1.184 g / cm 3 In addition, in the above scheme, a small amount of antioxidants, anti-ultraviolet agents and other additives can also be added.

[0036] Among them, SBR-1500 series styrene butadiene rubber is SBR1500, and SBR-1700 series styrene butadiene rubber is SBR1712.

[0037] In addition, in the following embodiments, unless otherwise specified, each embodiment has passed the insulation performance test.

[0038] The experimental groups and experimental results selected in Example 1 are shown in Table 1.

[0039] Table 1

[0040]

[0041]

[0042] It can be seen from the above experiments that, overall, the increase of silicon nitride powder filler will increase the thermal conductivity of the system. However, with the increase of silicon nitride powder filler, the change of tensile strength is small, but the elongation at break will be significantly reduced, and the resilience will decrease to a certain extent. The reason may be that silicon nitride has a greater impact on the rigidity of the system. After increasing the hardness, it will cause the cohesion of the system to decrease and the resilience to decrease. In addition, the total mass of the filler should not exceed 30 parts by mass. Although the increase of filler will enhance the thermal conductivity, it will also reduce the resilience and elongation at break, which will have an adverse effect on the mechanical properties of the system.

[0043] In addition, on the above basis, when the mass parts of SBR-1500 series styrene butadiene rubber are 20-25, and the mass parts of SBR-1700 series styrene butadiene rubber are 35-40 parts, the mechanical properties of the system as a whole are better, and SBR-1700 series styrene butadiene rubber (i.e., SBR1712 used in the present embodiment) has good softness, and the oil agent therein can improve the overall resilience of the system as a whole, and make up for the poor bonding ability of silicon nitride in the system, causing the loss of hardening of the system, but too much addition of SBR-1700 will also affect the overall tensile strength. When the amount of addition of SBR-1500 series styrene butadiene rubber is too much, it will not only cause the overall resilience to decrease, but also reduce the elongation at break, and at the same time, it may also cause the system thermal conductivity to have a certain loss due to the insufficient dispersibility of the filler.

[0044] Example 2: This example is based on Examples 1-12, and different mass ratios of acetate filaments and acetate staple fibers are set. The results are shown in Table 2.

[0045] Table 2

[0046]

[0047] Acetate long fibers and acetate staple fibers have different roles in the system. When the total content of acetate fibers remains unchanged, the increase of acetate long fibers can make the tensile strength stronger, but the rebound performance will deteriorate, while the increase of acetate staple fibers can enhance the rebound performance and deteriorate the tensile strength. The mass ratio of the above two fibers needs to be controlled within the range of 1.5 to 5:1.

[0048] Embodiment 3, based on Embodiments 1-12, this embodiment uses the following different silicone rubbers or fluorosilicone rubbers, and the specific types selected are as follows:

[0049] A1, same as Example 1

[0050] A2, hydroxy-terminated methylphenyl silicone rubber, phenyl molar content is 40%;

[0051] A3, hydroxy-terminated methylphenyl silicone rubber, phenyl molar content is 25%;

[0052] B1, hydroxyl-terminated silicone oil;

[0053] C1, methyl silicone rubber;

[0054] D1, methylphenyl silicone rubber, phenyl molar content is 30%;

[0055] D2, methylphenyl silicone rubber, phenyl molar content is 38%;

[0056] D3, methylphenyl silicone rubber, phenyl molar content is 44%;

[0057] E1, commercially available fluorosilicone rubber SE3180;

[0058] Note that in order to keep the experiment controllable, the viscosity of the selected rubber is in the range of 6000-15000mPa·s. In general, the viscosity has little effect on the performance of the material, but it has a certain effect on the fluidity during processing. It can be added according to the actual product situation. If the above materials are liquid, they can be added directly. If they are solid, they can be added in the form of rubber powder.

[0059] The experimental results in Example 3 are shown in Table 3.

[0060] Table 3

[0061] serial number Silicone rubber selection Tensile strength(mPa) Elongation at break (%) Resilience(%) Thermal conductivity (W / (m℃)) 3-1 A2 13.2 570 58.1 2.15 3-2 A3 13.1 541 54.2 2.18 3-3 B1 12.5 530 52.0 2.16 3-4 C1 11.0 514 50.9 2.17 3-5 D1 11.4 525 55.3 2.16 3-6 D2 11.7 518 54.8 2.18 3-7 D3 11.7 477 52.0 2.17 3-8 E1 13.0 552 60.0 2.26 3-9 No added silicone rubber 9.6 545 42.0 1.73

[0062] From the above experimental results, it can be seen that the components added with silicone rubber have better thermal conductivity, and the resilience, tensile strength and elongation at break are significantly improved, proving that silicone rubber not only improves its own mechanical properties but also provides good thermal conductivity, and also helps to further evenly distribute silicon nitride fillers. On the basis of the above, the mechanical properties obtained by using terminal hydroxymethylphenyl silicone rubber are stronger, which is generally close to fluorosilicone rubber, and the price is lower than fluorosilicone rubber.

[0063] In addition, in Example 3-2, it can be seen that when the phenyl content is too low, the overall rebound performance will decrease to a certain extent, and its morphology is similar to that of the non-substituted hydroxyl-terminated silicone rubber 3-3.

[0064] Example 4. Based on Examples 1-12, this example selects different ethylene-acrylate polymers to study their effects on the system. Specifically, the experimental results corresponding to the selected ethylene-acrylate polymers and the corresponding densities are shown in Table 4.

[0065] Table 4

[0066]

[0067] By comparison, we can see that the samples with ethylene-acrylate copolymer added have better tensile strength and resilience than the non-added experimental group. This may be because the ethylene-acrylate polymer uses its softness to improve the resilience of the system. At the same time, it also has a higher degree of interweaving, which improves the elongation at break and tensile strength of the system. Overall, through experimental determination, when the density of ethylene-acrylate polymer is 1.16-1.21 g / cm 3 The overall performance is better.

[0068] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An insulating material for isolating and protecting a circuit, characterized in that: The components are as follows according to mass parts: Natural rubber 100 parts SBR-1500 series styrene-butadiene rubber 20-25 parts SBR-1700 series styrene-butadiene rubber 35-40 parts Silicon nitride ceramic powder filler not more than 20 parts Alumina ceramic powder filler not more than 20 parts 5-10 parts of acetate fiber 3-5 parts of organic phosphorus flame retardant 2-4 parts sulfur 1-2 parts of accelerator Wherein, the total mass parts of the alumina ceramic powder filler and the silicon nitride powder filler are not higher than 30 parts.

2. The insulating material for isolating and protecting circuits according to claim 1, characterized in that: The acetate fibers include acetate filaments and acetate staple fibers. The aspect ratio of the acetate filaments is 500-1000, the aspect ratio of the acetate staple fibers is 50-100, and the mass ratio of the acetate filaments to the acetate staple fibers is 1.5-5:

1.

3. The insulating material for isolating and protecting circuits according to claim 1, characterized in that: The mass ratio of the alumina ceramic powder filler to the silicon nitride powder filler is 1:0.8-2.

4. The insulating material for isolating and protecting circuits according to claim 1, characterized in that: It also includes silicone rubber or fluorosilicone rubber, wherein the mass proportion of the silicone rubber or fluorosilicone rubber is 15 to 25 parts.

5. The insulating material for isolating and protecting a circuit according to claim 4, characterized in that: The silicone rubber or fluorosilicone rubber is selected from methylphenyl silicone rubber.

6. The insulating material for isolating and protecting a circuit according to claim 5, characterized in that: The methyl phenyl silicone rubber is selected from terminal hydroxyl methyl phenyl silicone rubber.

7. The insulating material for isolating and protecting a circuit according to claim 5, characterized in that: The molar content of phenyl in the methylphenyl silicone rubber is 30-40%.

8. The insulating material for isolating and protecting circuits according to claim 1, characterized in that: It also includes 2 to 4 parts by weight of an acrylic acid ester polymer.

9. The insulating material for isolating and protecting a circuit according to claim 8, characterized in that: The density of the acrylic esters ranges from 1.16 to 1.21 g / cm 3 .

10. The method for preparing an insulating material for isolating and protecting a circuit according to any one of claims 1 to 9, characterized in that: The steps include: S1. Mix the other components except sulfur and accelerator for 1 to 2 minutes at a temperature of 100 to 120°C. S2. Add sulfur and accelerator, raise the temperature to 130-140°C, mix for 60-90s, and discharge the material. The discharge temperature is 130-150°C.

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