Ultrathin-wall silicone tube for transformer as well as preparation method and application of ultrathin-wall silicone tube

Abstract

The invention relates to the technical field of pipes, and provides an ultrathin-wall silicone tube for a transformer and a preparation method and application of the ultrathin-wall silicone tube. The ultrathin-wall silicone tube is prepared from the following components in parts by weight: 100 parts of a silicone rubber composition, 0.8 to 1.2 parts of a vulcanizing agent, 0.3 to 1.0 part of a lubricating agent, 5 to 10 parts of a halogen-free flame retardant, 20 to 30 parts of a structure regulator, 0.4 to 0.6 part of an interfacial agent and 0.2 to 0.5 part of carbon black, wherein the silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, and the structure regulator is a poly (etherimide-siloxane) copolymer; the Shore A hardness of the silicone rubber composition is 70 to 80 degrees. The ultrathin-wall silicone tube provided by the invention does not use fluorine-containing materials, and can meet the characteristic requirements of instant high-temperature thermal shock resistance, long-term aging, high flexibility, high hardness and flame retardance.

Description

Technical Field

[0001] The invention belongs to the technical field of tubes and relates to an ultra-thin-wall silicone tube for a transformer and a preparation method and application thereof. Background Art

[0002] Per- and polyfluoroalkyl substances (PFAS) are a new type of pollutant that is extremely persistent, mobile, and potentially toxic, and may pose a series of risks to human health. Restricting the use of PFAS in commodities can protect the environment and human health and reduce the impact of PFAS on the environment. However, restricting the use of PFAS in commodities, especially those containing long-chain perfluoroalkyl substances, will affect the application of many products in the electronics field, including polytetrafluoroethylene (PTFE). This forces the industry to look for PFAS-free alternatives to meet new environmental standards.

[0003] At present, chargers for electronic products such as mobile phones and computers are all equipped with small transformers, and some high-end products require small transformers to meet the operating temperature level of 150°C. The small transformer wiring harness is insulated by covering it with PTFE insulating sleeve. The wiring harness needs to be wrapped around the core frame to form a coil, which requires the sleeve to have good flexibility and no cracks. During the manufacturing process, one end of the wiring harness needs to undergo a tinning process (430°C×0.5s), which requires the sleeve to withstand instantaneous high-temperature impact and must not deform, melt or crack. In addition, when the equipment clamps the tube for transportation for assembly, a too soft sleeve is prone to stacking or curling, so the hardness is required to be above 40D to avoid affecting the process. Considering the requirements for ultra-thin walls, halogen-free flame retardancy and other factors, many materials are not suitable for replacement.

[0004] In the prior art, various engineering materials are generally used to replace PTFE, including polyimide (PI), polyetheretherketone (PEEK), etc. However, engineering plastics have poor flexibility in application and there is a risk of cracking during winding, which affects the insulation performance of the bushing. If cross-linked polyolefin materials are used, the long-term high-temperature aging performance is poor, and the flame retardant reliability of ultra-thin walls is also low. Therefore, there is still no completely suitable solution in the prior art to achieve the replacement of PTFE tubes in small transformers. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide an ultra-thin-wall silicone tube, aiming to provide a PTFE insulating sleeve alternative for application in small transformers, meeting the requirements of instantaneous high-temperature thermal shock, long-term aging, high flexibility, high hardness and flame retardancy, and solving the drawbacks of the existing alternative technology for fluorine-containing pipes in the field of small transformers.

[0006] In order to achieve the above-mentioned object of the invention, on the one hand, the present invention provides an ultra-thin wall silicone tube for a transformer, which comprises the following components by weight:

[0007] 100 parts of silicone rubber composition, 0.8-1.2 parts of vulcanizing agent, 0.3-1.0 parts of lubricant, 5-10 parts of halogen-free flame retardant, 20-30 parts of structural regulator, 0.4-0.6 parts of surfactant and 0.2-0.5 parts of carbon black;

[0008] The silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, the structural regulator is a poly(etherimide-siloxane) copolymer; and the Shore A hardness of the silicone rubber composition is 70-80 degrees.

[0009] Preferably, the vinyl content of the methyl vinyl silicone rubber is 0.4 mol%-1 mol%; the vinyl content of the methyl phenyl vinyl silicone rubber is 0.4 mol%-1 mol% and the phenyl content is 20 mol%-34 mol%.

[0010] More preferably, and as an example of the present invention, the carbon black is carbon black N990.

[0011] Preferably, the Shore A hardness of the methyl vinyl silicone rubber is 70-80 degrees, and the Shore A hardness of the methyl phenyl vinyl silicone rubber is 70-80 degrees.

[0012] Preferably, the weight percentage of the methyl vinyl silicone rubber in the silicone rubber composition is 60%-75%.

[0013] Preferably, the vulcanizing agent is a two-component platinum vulcanizing agent; the lubricant is selected from at least one of hydroxy silicone oil, diphenylsilanediol, and methylphenyldiethoxysilane; the halogen-free flame retardant is selected from at least one of melamine cyanurate, melamine pyrophosphate, and diethylaluminum phosphinate; and the surfactant is a silane coupling agent.

[0014] More preferably, the silane coupling agent is at least one of γ-glycidylpropyltrimethoxysilane and hexamethyldisilazane.

[0015] More preferably, and as an example of the present invention, the silane coupling agent is silane coupling agent Z-6040.

[0016] Preferably, the poly(etherimide-siloxane) copolymer consists of polyetherimide block units and polysiloxane block units, and the weight percentage of the polysiloxane block units in the poly(etherimide-siloxane) copolymer is 10%-34%.

[0017] Preferably, the poly(etherimide-siloxane) copolymer is a poly(etherimide-siloxane) copolymer powder, and the particle size D90 of the poly(etherimide-siloxane) copolymer powder is less than or equal to 10 μm; the halogen-free flame retardant is a halogen-free flame retardant powder, and the D90 of the halogen-free flame retardant powder is 30-100 nm.

[0018] Preferably, the carbon black is N series carbon black; the wall thickness of the ultra-thin wall silicone tube is 0.1-0.15 mm, and the inner diameter of the ultra-thin wall silicone tube is 1.0-2.0 mm.

[0019] As a preferred embodiment of the present invention, the ultra-thin wall silicone tube comprises the following components by weight:

[0020] 100 parts of silicone rubber composition, 1 part of vulcanizing agent, 0.7 parts of lubricant, 5-10 parts of flame retardant, 20-30 parts of structural regulator, 0.4-0.6 parts of surfactant and 0.3 parts of carbon black;

[0021] The silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, the mass percentage of the methyl vinyl silicone rubber in the silicone rubber composition is 60%-75%, the Shore A hardness of the methyl vinyl silicone rubber is 75 degrees, the vinyl content is 0.7 mol%, and the Shore A hardness of the methyl phenyl vinyl silicone rubber is 75 degrees, the vinyl content is 0.7 mol%, and the phenyl content is 20 mol%-34 mol%; the vulcanizer is a two-component platinum vulcanizer, the two-component platinum vulcanizer is composed of equal parts of XH-PTC-09A and XH-PTC-09B, and the lubricant is a low molecular weight hydroxy silicone oil S H-238Y, the flame retardant is selected from melamine cyanurate MCA-1, melamine pyrophosphate MPP-M or diethyl aluminum phosphinate AT-100, the D90 of the flame retardant is ≤10μm, the structure regulator is poly(etherimide-siloxane) copolymer powder, the poly(etherimide-siloxane) copolymer is composed of polyetherimide block units and polysiloxane block units, the weight percentage of the polysiloxane block units in the poly(etherimide-siloxane) copolymer is 10%-34%; the particle size D90 is 30-100nm; the surfactant is silane coupling agent Z-6040, and the carbon black is thermal cracking carbon black N990.

[0022] As some preferred examples of the present invention, the ultra-thin wall silicone tube comprises the following components by weight:

[0023] 100 parts of silicone rubber composition, 1 part of vulcanizing agent, 0.3 parts of lubricant, 7 parts of flame retardant, 20-30 parts of structural regulator, 0.4-0.6 parts of surfactant and 0.2 parts of carbon black;

[0024] The silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, the mass percentage of the methyl vinyl silicone rubber in the silicone rubber composition is 68%, the Shore A hardness of the methyl vinyl silicone rubber is 70 degrees, the vinyl content is 0.7 mol%, and the Shore A hardness of the methyl phenyl vinyl silicone rubber is 70 degrees, the vinyl content is 0.7 mol%, and the phenyl content is 28 mol%; the vulcanizing agent is a two-component platinum vulcanizing agent, and the two-component platinum vulcanizing machine is composed of equal parts of XH-PTC-09A and XH-PTC-09B. The agent is diphenylsilane diol MY-R05, the flame retardant is melamine pyrophosphate MPP-M, the D90 of the flame retardant is ≤10μm, the structure regulator is poly(etherimide-siloxane) copolymer powder, the poly(etherimide-siloxane) copolymer is composed of polyetherimide block units and polysiloxane block units, the weight percentage of the polysiloxane block units in the poly(etherimide-siloxane) copolymer is 10%-34%, and the particle size D90 is 30-100nm; the surfactant is silane coupling agent Z-6040, and the carbon black is thermal cracking carbon black N990.

[0025] As some preferred examples of the present invention, the ultra-thin wall silicone tube comprises the following components by weight:

[0026] 100 parts of silicone rubber composition, 1.2 parts of vulcanizing agent, 1 part of lubricant, 7 parts of flame retardant, 20 parts of structural regulator, 0.4 parts of surfactant and 0.5 parts of carbon black;

[0027] The silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, the mass percentage of the methyl vinyl silicone rubber is 68%, the Shore A hardness of the methyl vinyl silicone rubber is 70-80 degrees, the vinyl content is 0.7 mol%, and the Shore A hardness of the methyl phenyl vinyl silicone rubber is 70-80 degrees, the vinyl content is 0.7 mol%, and the phenyl content is 20 mol%-34 mol%; the vulcanizing agent is a two-component platinum vulcanizing agent, and the two-component platinum vulcanizing machine is composed of equal parts of XH-PTC-09A and XH-PTC-09B The lubricant is methylphenyldiethoxysilane GX-826, the flame retardant is diethylaluminum phosphinate AT-100, the D90 of the flame retardant is ≤10μm, the structure regulator is poly(etherimide-siloxane) copolymer powder, the poly(etherimide-siloxane) copolymer consists of polyetherimide block units and polysiloxane block units, the weight percentage of the polysiloxane block units in the poly(etherimide-siloxane) copolymer is 20%, and the particle size D90 is 30-100nm; the surfactant is silane coupling agent Z-6040, and the carbon black is thermal cracked carbon black N990.

[0028] As some preferred examples of the present invention, the ultra-thin wall silicone tube comprises the following components by weight:

[0029] 100 parts of silicone rubber composition, 0.8-1.2 parts of vulcanizing agent, 0.5 parts of lubricant, 10 parts of flame retardant, 30 parts of structural regulator, 0.6 parts of surfactant and 0.4 parts of carbon black;

[0030] The silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, the mass percentage of the methyl vinyl silicone rubber in the silicone rubber composition is 60%-75%, the Shore A hardness of the methyl vinyl silicone rubber is 75 degrees, the vinyl content is 0.4mol%-1mol%, and the Shore A hardness of the methyl phenyl vinyl silicone rubber is 75 degrees, the vinyl content is 0.4mol%-1mol%, and the phenyl content is 34mol%; the vulcanizer is a two-component platinum vulcanizer, the two-component platinum vulcanizer is composed of equal parts of XH-PTC-09A and XH-PTC-09B, and the lubricant is a low molecular weight hydroxyl silicone The invention discloses a novel novel nanostructured carbon nanotube coating system, wherein the nanostructured carbon nanotube coating system comprises a nanostructured carbon nanotube coating system, and the nanostructured carbon nanotube coating system comprises a ...

[0031] On the other hand, the present invention provides a method for preparing the above-mentioned ultra-thin-wall silicone tube, comprising the following steps:

[0032] S1, mixing the structure regulator and the surfactant in the formula amount, and letting it stand to obtain a modified structure agent;

[0033] S2, mixing the silicone rubber composition, lubricant, halogen-free flame retardant, carbon black and the modified structural agent obtained in step S1, and letting it stand at room temperature to obtain a silicone rubber mixture;

[0034] S3, mixing the silicone rubber mixture obtained in step S2 with a vulcanizer of a formula amount, refining and thinning to obtain a silicone rubber mixture;

[0035] S4, cold-extrude and bake the silicone rubber mixture obtained in step S3 to obtain an ultra-thin-wall silicone tube.

[0036] Preferably, in step S1, the mixing is performed in a high-speed mixer.

[0037] Preferably, in step S1, the mixing temperature is 50-60°C, the stirring speed is 500-800 r / min, and the stirring time is 10-20 min.

[0038] Preferably, in step S1, the letting stand comprises opening the mixer cover and letting stand for 30-60 minutes.

[0039] Preferably, in step S2, the mixing is performed by adding the mixture into a kneader for mixing.

[0040] Preferably, in step S2, the mixing time is 20-30 minutes, and the standing time at room temperature is 8-10 hours.

[0041] Preferably, in step S3, the time for the open refining is 10-20 minutes, and the number of thin passes is 13-17 times, more preferably 15 times.

[0042] Preferably, in step S4, the cold extrusion is specifically to place the silicone rubber compound in an extruder for cold extrusion.

[0043] Preferably, in step S4, the baking is specifically a first stage of baking at 350°C for 1.5 min and a second stage of baking at 200°C for 30 min. The purpose of the baking is to perform external shaping by a short-term high-temperature baking and to melt and overlap the internal poly(etherimide-siloxane) powder to form a skeleton, and the second stage of long-term low-temperature baking is conducive to stable and orderly vulcanization and cross-linking.

[0044] On the other hand, the present invention provides the above-mentioned ultra-thin-wall silicone tube and the use of the ultra-thin-wall silicone tube prepared by the above-mentioned preparation method in a transformer.

[0045] Preferably, the transformer is a small transformer.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] (1) An ultra-thin-wall silicone tube provided in an embodiment of the present invention uses a silicone rubber composition, a halogen-free flame retardant, and a structural regulator as main raw materials, and compounded with a vulcanizer, a lubricant, a surfactant, and carbon black to optimize the performance of the silicone tube as a whole; the silicone material has good flexibility and high bending and breakage resistance reliability, wherein the poly(etherimide-siloxane) copolymer powder is used as a skeleton support after high-temperature melting to enhance the hardness of the silicone tube, and cooperates with methylphenyl vinyl silicone rubber and a halogen-free flame retardant to make the silicone tube meet the flame retardant grade of UL94 V2. In addition, the silicone tube after high-temperature vulcanization and cross-linking has excellent performance in both instantaneous high-temperature thermal shock and long-term high-temperature aging, which meets the replacement demand for PTFE insulating sleeves in small transformers and solves the drawbacks of PFAS FREE replacement technology in this field.

[0048] (2) According to the GB / T 531.1 test standard, the Shore D hardness of the ultra-thin wall silicone tube provided by the present invention is greater than or equal to 40 degrees; according to the ASTM D638 test standard, the elongation at break of the ultra-thin wall silicone tube provided by the present invention is greater than or equal to 200%, which meets the performance requirements of ultra-thin wall pipes under small transformer wrapping, winding process technology and working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a line graph showing the effect of different siloxane contents on hardness and toughness in the poly(etherimide-siloxane) copolymers of the embodiments of the present invention.

[0050] Figure 2 This is a SEM image of the ultra-thin-wall silicone tube provided in Comparative Example 4 of the present invention.

[0051] Figure 3 This is a SEM image of the ultra-thin-wall silicone tube provided in Example 6 of the present invention.

[0052] Figure 4 It is a line graph showing the effect of different weight portions of poly(etherimide-siloxane) copolymers on hardness and toughness in the embodiments of the present invention.

[0053] Figure 5 The figure is a diagram of the internal wiring harness structure of a small transformer in an application example. The reference numerals are: 1-1 is a core frame, 1-2 is an insulating sleeve, 1-3 is a wiring harness, and 1-3-1 is an outlet of the wiring harness extension line.

[0054] Figure 6 The following are photos and corresponding schematic diagrams of the 75A vulcanized rubber tube in the application example, which is piled up and rolled up when the insulating sleeve is assembled. The figure numerals: 2-1 is the wiring harness to be assembled, and 2-2 is the sleeve that is piled up and rolled up. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "an" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0057] In an embodiment of the present invention, the silicone rubber composition is formed by mixing methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber; wherein the vinyl content of the methyl vinyl silicone rubber and the methyl phenyl vinyl silicone rubber is 0.4 mol%-1 mol%, and the vinyl content directly affects the degree of vulcanization crosslinking of the rubber, and the vulcanization crosslinking mechanics and thermal stability are significantly increased, and the silicone rubber has excellent high and low temperature resistance, electrical insulation performance, deformation resistance and other characteristics; in addition, the methyl phenyl vinyl silicone rubber is a medium phenyl silicone rubber with a phenyl content of 20 mol%-34 mol%, which is prepared by introducing diphenyl siloxane chain segments (or methyl phenyl siloxane chain segments) into the molecular chain of the vinyl silicone rubber, and has ablation resistance and radiation resistance; the mixing ratio of the methyl vinyl silicone rubber and the methyl phenyl vinyl silicone rubber is 60:40 to 75:25. Considering that the medium phenyl silicone rubber has poor processability and high price, it is compounded with the methyl phenyl vinyl silicone rubber in a certain proportion, and the poly (etherimide-siloxane) copolymer powder with a large benzene ring and the halogen-free flame retardant are combined to make the silicone tube meet the flame retardant level of UL94 V2.

[0058] In an embodiment of the present invention, the vulcanizer is a two-component platinum vulcanizer, including a component A Pt catalyst and a component B hydrogenated silicone oil plus an inhibitor. Under the action of the Pt catalyst, the hydrogenated silicone oil undergoes a silylation crosslinking reaction with the vinyl double bonds of the silicone rubber, thereby significantly improving the heat resistance of the silicone rubber; further, the lubricant is one or more of low molecular weight hydroxy silicone oil, diphenylsilanediol, and methylphenyldiethoxysilane in any proportion. The rubber will harden during storage, and the plasticity value will decrease, resulting in a gradual loss of processing performance. This phenomenon is called the "structuring" effect, and the addition of the lubricant is beneficial to preventing and weakening this "structuring" tendency.

[0059] In an embodiment of the present invention, the halogen-free flame retardant is one or more of melamine cyanurate (MCA), melamine pyrophosphate (MPP), and diethyl aluminum phosphinate (ADP) flame retardants in any proportion. There is a halogen-free requirement in the electronics industry (i.e., Cl≤900ppm, Br≤900ppm, Cl+Br≤1500ppm requirements), so the flame retardant cannot use a halogen-containing system, and metal hydroxides such as magnesium hydroxide have a relatively low decomposition temperature and are not resistant to high temperatures, so they are not adopted. Moreover, since the casing is required to meet the UL94 V2 requirements, the flame retardant requirements are not high, and a small amount of halogen-free flame retardant can act as a flame retardant synergist to prevent the spread of flame; wherein the particle size D90 of the halogen-free flame retardant is less than or equal to 10μm, and the particle size D90 of the poly(etherimide-siloxane) copolymer powder is 30-100nm, and limiting the particle size can also improve the compatibility of the filler in the rubber, avoiding affecting the appearance and performance stability of the extruded casing.

[0060] In an embodiment of the present invention, the surfactant is a silane coupling agent; the surface tension of the poly(etherimide-siloxane) copolymer powder can be further adjusted to improve the wettability and dispersibility of the powder in silicone rubber, and the silane coupling agent is r-glycidylpropyltrimethoxysilane and hexamethyldisilazane; considering that the product of the embodiment of the present invention is applied to a small transformer, the specifications of the ultra-thin-wall silicone tube are further limited, the wall thickness is limited to 0.1-0.15 mm, and the inner diameter is limited to 1.0-2.0 mm.

[0061] In the embodiment of the present invention, silicone rubber is used as the main substrate, and the material has good flexibility and high bending and breakage resistance reliability. The compounded poly(etherimide-siloxane) copolymer powder is used as a skeleton support after high-temperature melting to enhance the hardness of the silicone tube, and cooperates with methylphenyl vinyl silicone rubber and halogen-free flame retardant to make the silicone tube meet the flame retardant level of UL94 V2. In addition, the silicone tube after high-temperature vulcanization and cross-linking has excellent performance in both instantaneous high-temperature thermal shock and long-term high-temperature aging, which meets the replacement demand for PTFE insulating sleeves in small transformers and also solves the drawbacks of PFAS FREE (PFAS-free) replacement technology in this field.

[0062] The following examples of some embodiments of the present invention are provided, and the purpose is not to limit the scope of the present invention. It should be noted that the numerical values ​​given in the following examples are as accurate as possible, but those skilled in the art understand that due to the measurement errors and experimental operation problems that cannot be avoided, each numeral should be understood as an approximate number, rather than an absolutely accurate numerical value. For example, due to the error of the weighing apparatus, the weight value of each raw material in each example material should be understood to have an error of ± 2% or ± 1%.

[0063] The materials shown in Table 1 are used in the examples of the present invention:

[0064] Table 1

[0065]

[0066]

[0067]

[0068] The poly(etherimide-siloxane) copolymer is composed of polyetherimide block units and polysiloxane block units, and the siloxane content of the poly(etherimide-siloxane) copolymer refers to the weight percentage of the polysiloxane block units in the poly(etherimide-siloxane) copolymer.

[0069] The ultra-thin wall silicone tube produced in the embodiment of the present invention is tested by the standards summarized in Table 2 to measure the performance of the tube.

[0070] Table 2

[0071]

[0072]

[0073] The Shore D hardness is tested after the material is pressed and vulcanized, and the value is read after 15 seconds using a Shore D hardness tester; Flame retardant UL94 V2 is vulcanized into a 3mm thick sample by pressing the material into sheets. After being ignited vertically, the sample stops burning within 30 seconds. The V2 standard allows for dripping of burning materials. In this case, it is possible to consider using materials that have a flame retardant effect but cannot form a hard carbon shell after burning. There is a risk of dripping causing the bottom cotton to burn, such as the lower-cost MCA. Phosphorus-containing MPP and ADP are solid phase flame retardants, and the carbon layer formed can prevent dripping. Silicone can meet the 200℃ service temperature level, which is much higher than the 150℃ service temperature required for high-end transformers. According to the UL224 standard, the aging test conditions for 200℃ temperature grade silicone are 232℃×168h. Tin immersion is tested at the process site. The ultra-thin wall silicone tube is sleeved on the wiring harness. The equipment clamp is used to immerse the wiring harness end in 430℃ tin liquid and detach it after 0.5s. The end face of the sleeve is just in contact with the tin liquid to observe whether the sleeve is melted and deformed.

[0074] Example 1

[0075] Ultra-thin wall silicone tube, the raw materials by weight are as follows:

[0076] 100 parts of a silicone rubber composition (composed of 75 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%) and 25 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%, phenyl content 20 mol%));

[0077] 1.0 part of vulcanizing agent (composed of 0.5 part of component A XH-PTC-09A and 0.5 part of component B XH-PTC-09B of two-component platinum vulcanizing agent);

[0078] 0.7 parts of lubricant (low molecular weight hydroxy silicone oil, SH-238Y);

[0079] 5 parts of halogen-free flame retardant (melamine cyanurate MCA-1, particle size D90≤10μm);

[0080] 20 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-5, siloxane content 34 wt%, particle size D90 30-100 nm);

[0081] 0.4 parts of surfactant (silane coupling agent Z-6040);

[0082] 0.3 parts of carbon black (thermal black N990).

[0083] Example 2

[0084] Ultra-thin wall silicone tube. The difference from Example 1 is:

[0085] 100 parts of a silicone rubber composition (composed of 68 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%) and 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%, phenyl content 28 mol%));

[0086] 7 parts of halogen-free flame retardant (melamine cyanurate MCA-1, particle size D90≤10μm);

[0087] 25 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-3, siloxane content 20 wt%, particle size D90 30-100 nm);

[0088] 0.5 parts of surfactant (silane coupling agent Z-6040).

[0089] The specific types and weight proportions of the remaining ingredients are the same as those in Example 1.

[0090] Example 3

[0091] Ultra-thin wall silicone tube. The difference from Example 1 is:

[0092] 100 parts of a silicone rubber composition (composed of 60 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%) and 40 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%, phenyl content 34 mol%));

[0093] 10 parts of halogen-free flame retardant (melamine cyanurate MCA-1, particle size D90≤10μm);

[0094] 30 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-1, siloxane content 10 wt%, particle size D90 30-100 nm);

[0095] 0.6 parts of surfactant (silane coupling agent Z-6040).

[0096] The specific types and weight proportions of the remaining ingredients are the same as those in Example 1.

[0097] Example 4

[0098] Ultra-thin wall silicone tube. The difference from Example 1 is:

[0099] 5 parts of halogen-free flame retardant (melamine pyrophosphate MPP-M, particle size D90≤10μm).

[0100] The specific types and weight proportions of the remaining ingredients are the same as those in Example 1.

[0101] Example 5

[0102] Ultra-thin wall silicone tube. The difference from Example 1 is:

[0103] 5 parts of halogen-free flame retardant (diethylaluminum phosphinate AT-100, particle size D90≤10 μm).

[0104] The specific types and weight proportions of the remaining ingredients are the same as those in Example 1.

[0105] Example 1-Example 5 was prepared according to the following ultra-thin-wall silicone tube production process: weigh each raw material according to the raw material formula of the example; put the poly(etherimide-siloxane) copolymer powder into a high-speed mixer, spray the silane coupling agent into the high-speed mixer, stir at 50°C and 500r / min for 10 minutes, open the mixer cover and let it stand for 30 minutes to obtain a modified structural agent; add methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, lubricant, halogen-free flame retardant, modified structural agent, and carbon black into a kneader for mixing for 20 minutes, and then let it stand at room temperature for 8 hours. A silicone rubber mixture is obtained; platinum vulcanizer B component is added to the silicone rubber mixture and the mixture is kneaded for 5 minutes, and then platinum vulcanizer A component is added and the mixture is kneaded for 5 minutes, and then the mixture is thin-rolled 15 times at a roller spacing of 1 mm to obtain a silicone rubber mixture; the silicone rubber mixture is placed in an extruder for cold extrusion according to the specifications of an inner diameter of 1.05±0.05 mm and a wall thickness of 0.125±0.025 mm to obtain a silicone tube semi-finished product; the silicone tube semi-finished product is placed in a tunnel furnace for vulcanization, baked at 350°C for 1.5 minutes in the first stage and at 200°C for 30 minutes in the second stage, internally melt-jointed and vulcanized and cross-linked to obtain an ultra-thin-wall silicone tube.

[0106] Example 6

[0107] Ultra-thin wall silicone tube, the raw materials by weight are as follows:

[0108] 100 parts of a silicone rubber composition (composed of 68 parts of methyl vinyl silicone rubber (Shore A hardness 70, vinyl content 0.7 mol%) and 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 70, vinyl content 0.7 mol%, phenyl content 28 mol%));

[0109] 1.0 part of vulcanizing agent (composed of 0.5 part of component A XH-PTC-09A and 0.5 part of component B XH-PTC-09B of two-component platinum vulcanizing agent);

[0110] 0.3 parts of lubricant (diphenylsilanediol, MY-R05);

[0111] 7 parts of halogen-free flame retardant (melamine pyrophosphate MPP-M, particle size D90≤10μm);

[0112] 25 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-1, siloxane content 10 wt%, particle size D90 30-100 nm);

[0113] 0.5 parts of surfactant (silane coupling agent Z-6040);

[0114] 0.2 parts of carbon black (thermal black N990).

[0115] Example 7

[0116] Ultra-thin wall silicone tube. The difference from Example 6 is:

[0117] 25 parts of a structural regulator (specifically, poly(etherimide-siloxane) copolymer powder-2, with a siloxane content of 15 wt % and a particle size D90 of 30-100 nm).

[0118] The specific types and weight proportions of the remaining ingredients are the same as those in Example 6.

[0119] Example 8

[0120] Ultra-thin wall silicone tube. The difference from Example 6 is:

[0121] 25 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-3, siloxane content 20 wt %, particle size D90 30-100 nm).

[0122] The specific types and weight proportions of the remaining ingredients are the same as those in Example 6.

[0123] Example 9

[0124] Ultra-thin wall silicone tube. The difference from Example 6 is:

[0125] 25 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-4, siloxane content 28 wt %, particle size D90 30-100 nm).

[0126] The specific types and weight proportions of the remaining ingredients are the same as those in Example 6.

[0127] Example 10

[0128] Ultra-thin wall silicone tube. The difference from Example 6 is:

[0129] 25 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-5, siloxane content 34 wt %, particle size D90 30-100 nm).

[0130] The specific types and weight proportions of the remaining ingredients are the same as those in Example 6.

[0131] Embodiment 11

[0132] Ultra-thin wall silicone tube. The difference from Example 6 is:

[0133] 20 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-3, siloxane content 20 wt%, particle size D90 30-100 nm);

[0134] 0.4 parts of surfactant (specifically silane coupling agent Z-6040).

[0135] The specific types and weight proportions of the remaining ingredients are the same as those in Example 6.

[0136] Example 12

[0137] Ultra-thin wall silicone tube. The difference from Example 6 is:

[0138] 30 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-3, siloxane content 20 wt%, particle size D90 30-100 nm);

[0139] 0.6 parts of surfactant (specifically silane coupling agent Z-6040).

[0140] The specific types and weight proportions of the remaining ingredients are the same as those in Example 6.

[0141] Example 6-Example 12 was prepared according to the following ultra-thin-wall silicone tube production process: weigh each raw material according to the raw material formula of the example; put the poly(etherimide-siloxane) copolymer powder into a high-speed mixer, spray the silane coupling agent into the high-speed mixer, stir at 55°C and 600r / min for 13 minutes, open the mixer cover and let it stand for 40 minutes to obtain a modified structural agent; add methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, lubricant, halogen-free flame retardant, modified structural agent, and carbon black into a kneader for mixing for 25 minutes, and then let it stand at room temperature for 9 hours. A silicone rubber mixture is obtained; platinum vulcanizer B component is added to the silicone rubber mixture and the mixture is kneaded for 7 minutes, and then platinum vulcanizer A component is added and the mixture is kneaded for 8 minutes, and then the mixture is thin-rolled 15 times at a roller spacing of 0.7 mm to obtain a silicone rubber mixture; the silicone rubber mixture is placed in an extruder for cold extrusion according to the specifications of an inner diameter of 1.35±0.05 mm and a wall thickness of 0.125±0.025 mm to obtain a silicone tube semi-finished product; the silicone tube semi-finished product is placed in a tunnel furnace for vulcanization, baked at 350°C for 1.5 minutes in the first stage and at 200°C for 30 minutes in the second stage, internally melt-jointed and vulcanized and cross-linked to obtain an ultra-thin-wall silicone tube.

[0142] Embodiment 13

[0143] Ultra-thin wall silicone tube, the raw materials by weight are as follows:

[0144] 100 parts of a silicone rubber composition (composed of 68 parts of methyl vinyl silicone rubber (Shore A hardness 70, vinyl content 0.7 mol%) and 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 70, vinyl content 0.7 mol%, phenyl content 28 mol%));

[0145] 1.2 parts of vulcanizing agent (composed of 0.6 parts of component A XH-PTC-09A and 0.6 parts of component B XH-PTC-09B of two-component platinum vulcanizing agent);

[0146] Lubricant 1.0 part (methylphenyldiethoxysilane, GX-826);

[0147] 7 parts of halogen-free flame retardant (diethylaluminum phosphinate AT-100, particle size D90≤10μm);

[0148] 20 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-3, siloxane content 20 wt%, particle size D90 30-100 nm);

[0149] 0.4 parts of surfactant (silane coupling agent Z-6040);

[0150] 0.5 parts of carbon black (thermal black N990).

[0151] Embodiment 14

[0152] Ultra-thin wall silicone tube. Differences from Example 13 are:

[0153] 100 parts of a silicone rubber composition (consisting of 68 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%), and 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%, phenyl content 28 mol%)).

[0154] The specific types and mass parts of the remaining ingredients are the same as those in Example 13.

[0155] Embodiment 15

[0156] Ultra-thin wall silicone tube. Differences from Example 13 are:

[0157] 100 parts of a silicone rubber composition (composed of 68 parts of methyl vinyl silicone rubber (Shore A hardness 80 degrees, vinyl content 0.7 mol%) and 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 80 degrees, vinyl content 0.7 mol%, phenyl content 28 mol%));

[0158] The specific types and mass parts of the remaining ingredients are the same as those in Example 13.

[0159] Example 13-Example 15 were prepared according to the following ultra-thin-wall silicone tube production process: weigh the raw materials according to the raw material formula of the example; put the poly(etherimide-siloxane) copolymer powder into a high-speed mixer, spray the silane coupling agent into the high-speed mixer, stir at 55°C and 700r / min for 17 minutes, open the mixer cover and let it stand for 50 minutes to obtain a modified structural agent; add methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, lubricant, halogen-free flame retardant, modified structural agent, and carbon black into a kneader and mix for 25 minutes, then let it stand at room temperature for 9 hours, A silicone rubber mixture is obtained; platinum vulcanizer B component is added to the silicone rubber mixture and the mixture is kneaded for 8 minutes, and then platinum vulcanizer A component is added to the silicone rubber mixture and the mixture is kneaded for 7 minutes, and then the mixture is thin-rolled 15 times at a roller spacing of 0.8 mm to obtain a silicone rubber mixture; the silicone rubber mixture is placed in an extruder for cold extrusion according to the specifications of an inner diameter of 1.65±0.05 mm and a wall thickness of 0.125±0.025 mm to obtain a silicone tube semi-finished product; the silicone tube semi-finished product is placed in a tunnel furnace for vulcanization, baked at 350°C for 1.5 minutes in the first stage and at 200°C for 30 minutes in the second stage, internally melt-jointed and vulcanized and cross-linked to obtain an ultra-thin-wall silicone tube.

[0160] Example 16

[0161] Ultra-thin wall silicone tube, the raw materials by weight are as follows:

[0162] 100 parts of a silicone rubber composition (composed of 60 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.4 mol%) and 40 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.4 mol%, phenyl content 34 mol%));

[0163] 0.8 parts of vulcanizing agent (composed of 0.4 parts of component A XH-PTC-09A and 0.4 parts of component B XH-PTC-09B of two-component platinum vulcanizing agent);

[0164] 0.5 parts of lubricant (low molecular weight hydroxy silicone oil, SH-238Y);

[0165] 10 parts of halogen-free flame retardant (diethylaluminum phosphinate AT-100, particle size D90≤10μm);

[0166] 30 parts of a structure regulator (poly(etherimide-siloxane) copolymer powder-1, siloxane content 10 wt%, particle size D90 30-100 nm);

[0167] 0.6 parts of surfactant (silane coupling agent Z-6040);

[0168] 0.4 parts of carbon black (thermal black N990).

[0169] Embodiment 17

[0170] Ultra-thin wall silicone tube. The difference from Example 16 is:

[0171] 100 parts of a silicone rubber composition (composed of 60 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%) and 40 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 0.7 mol%, phenyl content 34 mol%));

[0172] 1.0 part of vulcanizing agent (consisting of 0.5 part of component A XH-PTC-09A and 0.5 part of component B XH-PTC-09B of two-component platinum vulcanizing agent).

[0173] The specific types and mass parts of the remaining ingredients are the same as those in Example 16.

[0174] Embodiment 18

[0175] Ultra-thin wall silicone tube. The difference from Example 16 is:

[0176] 100 parts of a silicone rubber composition (consisting of 60 parts of methyl vinyl silicone rubber (Shore A hardness 75, vinyl content 1.0 mol%) and 40 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75, vinyl content 1.0 mol%, phenyl content 34 mol%)).

[0177] 1.2 parts of vulcanizing agent (consisting of 0.6 parts of component A XH-PTC-09A and 0.6 parts of component B XH-PTC-09B of a two-component platinum vulcanizing agent).

[0178] The specific types and mass parts of the remaining ingredients are the same as those in Example 16.

[0179] Examples 16-18 were prepared according to the following ultra-thin-wall silicone tube production process: weigh the raw materials according to the raw material formula of the example; put the poly(etherimide-siloxane) copolymer powder into a high-speed mixer, spray the silane coupling agent into the high-speed mixer, stir at 60°C and 800r / min for 20 minutes, open the mixer cover and let it stand for 60 minutes to obtain a modified structural agent; add methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, lubricant, halogen-free flame retardant, modified structural agent, and carbon black into a kneader and mix for 30 minutes, then let it stand at room temperature for 10 hours to obtain Silicone rubber mixture; add platinum vulcanizer B component to the silicone rubber mixture and knead for 10 minutes, then add platinum vulcanizer A component and knead for 10 minutes, and then thin pass 15 times at a roller distance of 0.5 mm to obtain a silicone rubber mixture; place the silicone rubber mixture in an extruder and perform cold extrusion according to the specifications of an inner diameter of 1.95±0.05 mm and a wall thickness of 0.125±0.025 mm to obtain a silicone tube semi-finished product; place the silicone tube semi-finished product in a tunnel furnace for vulcanization, bake at 350°C for 1.5 minutes in the first stage, and bake at 200°C for 30 minutes in the second stage, melt-joint the inside and perform vulcanization cross-linking to obtain an ultra-thin wall silicone tube.

[0180] Comparative Example 1

[0181] On the basis of Example 1, melamine cyanurate MCA-1 (particle size D90≤10 μm) was replaced with magnesium hydroxide H5 (particle size D90≤10 μm), and the other components, proportions and production process parameters were consistent with those in Example 1.

[0182] Comparative Example 2

[0183] On the basis of Example 3, melamine cyanurate MCA-1 (particle size D90≤10μm) was replaced with melamine cyanurate MCA-1 (particle size D90≤100μm), and the other components, proportions and production process parameters were consistent with those in Example 1.

[0184] Comparative Example 3

[0185] On the basis of Example 6, the poly(etherimide-siloxane) copolymer powder-1 (siloxane content 10wt%, particle size D90 30-100nm) is replaced with poly(etherimide-siloxane) copolymer powder-6 (siloxane content 45wt%, particle size D90 30-100nm), and the other components, proportions and production process parameters are consistent with Example 6.

[0186] Comparative Example 4

[0187] On the basis of Example 6, the poly(etherimide-siloxane) copolymer powder-1 (siloxane content 10wt%, particle size D90 30-100nm) is replaced with polyetherimide powder (siloxane content 0wt%, particle size D90 30-100nm), and the other components, proportions and production process parameters are consistent with Example 6.

[0188] Comparative Example 5

[0189] On the basis of Example 6, the poly(etherimide-siloxane) copolymer powder-1 (siloxane content 10wt%, particle size D90 30-100nm) is replaced with silicone resin (methyl MQ silicone resin powder DY-MQ803), and the other components, proportions and production process parameters are consistent with Example 6.

[0190] Comparative Example 6

[0191] On the basis of Example 6, the poly(etherimide-siloxane) copolymer powder-1 (siloxane content 10wt%, particle size D90 30-100nm) is replaced with poly(etherimide-siloxane) copolymer powder-7 (siloxane content 10wt%, particle size D90≤1μm), and the other components, proportions and production process parameters are consistent with Example 6.

[0192] Comparative Example 7

[0193] On the basis of Example 11, the mass proportion of the structure regulator was adjusted from 20 parts to 10 parts, and the mass proportion of the surfactant was adjusted from 0.4 parts to 0.2 parts. The other components, proportions and production process parameters remained consistent with Example 11.

[0194] Comparative Example 8

[0195] On the basis of Example 11, the mass proportion of the structure regulator is adjusted from 20 parts to 40 parts, and the mass proportion of the surfactant is adjusted from 0.4 parts to 0.8 parts. The other components, proportions and production process parameters remain consistent with Example 11.

[0196] Comparative Example 9

[0197] On the basis of Example 13, the silicone rubber composition is replaced with: 68 parts of methyl vinyl silicone rubber (Shore A hardness of 60 degrees, vinyl content of 0.7 mol%), 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness of 60 degrees, vinyl content of 0.7 mol%, phenyl content of 28 mol%), and the remaining components, proportions and production process parameters are consistent with Example 13.

[0198] Comparative Example 10

[0199] On the basis of Example 13, the silicone rubber composition is replaced with: 68 parts of methyl vinyl silicone rubber (Shore A hardness of 85 degrees, vinyl content of 0.7 mol%), 32 parts of methyl phenyl vinyl silicone rubber (Shore A hardness of 85 degrees, vinyl content of 0.7 mol%, phenyl content of 28 mol%), and the remaining components, proportions and production process parameters are consistent with Example 13.

[0200] Comparative Example 11

[0201] On the basis of Example 16, the silicone rubber composition is replaced by:

[0202] 60 parts of methyl vinyl silicone rubber (hardness 75A, vinyl content 0.1 mol%), 40 parts of methyl phenyl vinyl silicone rubber (hardness 75A, vinyl content 0.1 mol%, phenyl content 34 mol%)}.

[0203] At the same time, the vulcanizing agent is replaced with 0.4 parts (specifically, it includes 0.2 parts of component A XH-PTC-09A of the two-component platinum vulcanizing agent and 0.2 parts of component B XH-PTC-09B), and the other components, proportions and production process parameters are consistent with Example 16.

[0204] Comparative Example 12

[0205] On the basis of Example 16, the silicone rubber composition is replaced by:

[0206] 60 parts of methyl vinyl silicone rubber (Shore A hardness 75 degrees, vinyl content 1.5 mol%), 40 parts of methyl phenyl vinyl silicone rubber (Shore A hardness 75 degrees, vinyl content 1.5 mol%, phenyl content 34 mol%).

[0207] At the same time, the vulcanizing agent is replaced with: 2.0 parts of vulcanizing agent (specifically including 1.0 parts of component A XH-PTC-09A of a two-component platinum vulcanizing agent and 1.0 parts of component B XH-PTC-09B), and the remaining components, proportions and production process parameters are consistent with those in Example 16.

[0208] Effect evaluation

[0209] The casing prepared in the embodiment of the present invention was tested, and the test results are shown in Table 3 to Table 7:

[0210] Table 3

[0211]

[0212]

[0213] The embodiment of the present invention adopts a silicone rubber composition, a halogen-free flame retardant, and a structure regulator as the main raw materials, and compounding a vulcanizer, a lubricant, a surfactant, and carbon black to achieve various performance indicators of the silicone tube, wherein the methylphenyl vinyl silicone rubber and the poly(etherimide-siloxane) copolymer chain segments contain a benzene ring structure, which is relatively high in carbon content. The oxidation reaction during combustion requires more sufficient oxygen to assist combustion. The carbon dioxide produced after combustion will also dilute the surrounding oxygen concentration, and a carbon layer will be formed to isolate the gas. In addition, the high-temperature decomposition of the ether bond will also absorb some heat, and the halogen-free flame retardant will also serve as a flame retardant synergist to achieve the UL94 V2 flame retardant performance of the material. In summary, the higher the methylphenyl vinyl silicone rubber and phenyl content, the higher the poly(etherimide-siloxane) copolymer and benzene ring content (that is, the lower the siloxane content), and the higher the proportion of halogen-free flame retardant, the better the flame retardant effect, but on the other hand, the methylphenyl vinyl silicone rubber has a processability deviation, and the more fillers it has, the more it affects its processability, and the toughness of the prepared casing will also decrease.

[0214] It can be seen from Examples 1 to 3 and the test results in Table 3 that by adjusting the proportion of the methylphenyl vinyl silicone rubber component and the phenyl content, the proportion of the poly(etherimide-siloxane) copolymer powder component and the siloxane content, and the proportion of the halogen-free flame retardant component, it is shown that the flame retardancy and processability are within the scope defined by the present invention. When the benzene content and the flame retardant are at the lowest proportion in Example 1, the UL94 V2 flame retardancy can be met, and when the methylphenyl vinyl silicone rubber and filler in Example 3 are at the highest, processability is also achieved, and the prepared silicone tube meets the toughness requirement of ≥200%.

[0215] It can be seen from Example 1, Example 4, Example 5, Comparative Example 1 and test result Table 3 that by adjusting the types of MCA, MPP, and ADP flame retardants as flame retardant synergists, UL94 V2 flame retardancy and other requirements can also be met; however, if the flame retardant is adjusted to Mg(OH)2, the decomposition temperature is low, and it is easy to decompose and cause the sleeve to fail during long-term high-temperature aging tests.

[0216] It can be seen from Example 3, Comparative Example 2 and test result Table 3 that a halogen-free flame retardant with too large a particle size will affect its dispersion in silicone rubber and have poor compatibility, thereby affecting the mechanical and insulating properties of the silicone tube.

[0217] Table 4

[0218]

[0219] The siloxane structure in the poly(etherimide-siloxane) copolymer in the embodiment of the present invention has the same siloxane bond (-Si-O-Si-) unit as silicone rubber. When mixed at high temperature, the molecular chains will be entangled with each other to a certain extent. As the proportion of siloxane increases, the compatibility of the two is better, and the impact on the toughness of the prepared silicone tube is smaller. However, the poly(etherimide-siloxane) copolymer with a higher siloxane content increases in softness and decreases in hardness, and the effect of improving the hardness of the prepared silicone material is also reduced.

[0220] Examples 6 to 10 and Comparative Examples 3 and 4 adopt the control variable method, keep other components, proportions and production processes unchanged, adjust the siloxane content in the poly(etherimide-siloxane) copolymer to observe the effect on mechanics and hardness. From the test results in Table 4 and Figure 1 It can be seen that within the limited range of the present invention, the requirements of mechanics and hardness are met. As the siloxane content in the poly(etherimide-siloxane) copolymer increases, the mechanical strength and elongation of the silicone tube gradually increase, while the hardness gradually decreases; Comparative Example 3 shows that when the siloxane content in the poly(etherimide-siloxane) copolymer is greater than a certain range, the mechanical strength of the prepared sleeve tends to be flat or decrease, the toughness increases slowly, and the hardness is lower than the lower limit; Comparative Example 4 shows that the siloxane content in the poly(etherimide-siloxane) copolymer tends to 0, and the compatibility with the silicone rubber composition deteriorates, Figure 2 It can be seen that there is a relatively obvious interface between the two, the mechanical properties are significantly reduced, the hardness will be improved, and the insulation performance is mainly related to the material and density. If the compatibility is poor, it is easy to form defects such as gaps, voids, and microcracks, and the electrical properties will also decrease accordingly; Figure 3 As shown, in Example 6, the silicone rubber is used as the main substrate, and there is no particularly obvious boundary between the silicone rubber and the filled poly(etherimide-siloxane) copolymer. The silicone structure can enhance the compatibility of the two.

[0221] It can be seen from Example 6, Comparative Examples 5-Comparative Examples 6 and test result Table 4 that the silicone resin in Comparative Example 5 is a highly branched organic silicone polymer, which has a certain reinforcing effect on the strength and hardness of silicone rubber, but the effect is limited, and it is easy to cause rubber structuring and affect its electrical properties, and the flame retardant performance does not meet the UL94 V2 standard; the poly(etherimide-siloxane) copolymer powder in Comparative Example 6 has a large particle size, which will affect the dispersion in silicone rubber, the compatibility becomes poor, the strength enhancement effect on silicone rubber is general, the elongation is lower than the minimum limit, and the electrical properties are also significantly weakened.

[0222] Table 5

[0223]

[0224] The poly(etherimide-siloxane) copolymer powder in the embodiment of the present invention has a reinforcing effect on the silicone rubber. The molecular chain itself carries a large benzene ring structure, the molecular rotation is restricted, and it exhibits a relatively high hardness. During a high-temperature vulcanization, the poly(etherimide-siloxane) copolymer powder melts, and some of them overlap each other to form a rigid skeleton. As the proportion of the components increases, the rigidity of the silicone rubber can be significantly improved, and the toughness will also decrease relatively. Example 8, Example 11, Example 12, Comparative Example 7, and Comparative Example 8 adopt the control variable method, keep other components, proportions and production processes unchanged, adjust the amount of poly(etherimide-siloxane) copolymer powder to observe the effect on mechanics and hardness. From the test results in Table 5 and Figure 4 It can be seen that with the increase in the proportion of the poly(etherimide-siloxane) copolymer powder, the toughness is gradually weakened, but the hardness of the material is gradually increased, and the mechanical strength shows a trend of first increasing and then tending to be flat or weakened. Within the scope defined by the present invention, the mechanical, hardness and other indicators are met, but in Example 7, the poly(etherimide-siloxane) copolymer is equal to 10 parts, and the small proportion leads to the inability to overlap each other during high-temperature vulcanization to form a rigid skeleton, and the hardness reinforcement effect on the silicone material is not good. In Example 8, when the poly(etherimide-siloxane) copolymer is equal to 40 parts, the excessive proportion affects the slippage of the silicone material molecular chain, the toughness is poor, and the overall mechanical properties and electrical insulation properties are low.

[0225] Table 6

[0226]

[0227]

[0228] The hardness of the silicone rubber composition in the embodiment of the present invention will affect the hardness of the final product and the ease with which the rubber eats the material; Example 13-Example 15, Comparative Example 9-Comparative Example 10 keep other components, proportions and production processes unchanged, and adjust the hardness of the methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber in the raw materials to observe the effect on the hardness and processability of the product; It can be seen from the test result Table 6 that with the increase of the hardness of the methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber in the raw materials, the hardness of the prepared silicone material will also increase, the mechanical strength will gradually increase, the toughness will deteriorate, and the production processability will also deteriorate; When the silicone material hardness prepared in Comparative Example 9 using a silicone rubber composition with a Shore A hardness of 60 degrees cannot meet the minimum limit, Comparative Example 10 uses a silicone rubber composition with a Shore A hardness of 85 degrees. The rubber is easily structured during storage and preparation, the overall hardness becomes hard, it is difficult to cover the filler, and the processability is poor.

[0229] Table 7

[0230]

[0231] The vinyl content and the number of vulcanizing agents in the rubber in the embodiment of the present invention determine the degree of vulcanization of the silicone tube, and the degree of vulcanization of the silicone tube will affect its long-term aging and instantaneous thermal shock performance. The molecular chain is vulcanized and cross-linked into a three-dimensional network structure. The vulcanized product is no longer plastic, and its shape remains fixed at high temperature. It will not decompose and lose its performance until it reaches the decomposition temperature; Example 16, Example 17, Example 18, Comparative Example 11, Comparative Example 12 observe the influence on the heat resistance of the silicone tube by adjusting the vinyl content and the number of vulcanizing agents of methyl vinyl silicone rubber and methylphenyl vinyl silicone rubber; It can be seen from the test results in Table 7 that with the increase of vinyl content and the number of vulcanizing agents, the crosslinking degree of the silicone tube is increasing, and the mechanical strength and hardness are gradually increasing. On the contrary, the toughness has dropped, and it can meet 232°C within the limited range. ×168h long-term aging elongation at break ≥100% requirement, meet the 430℃×0.5s tin immersion instantaneous thermal shock requirements of no melting, no deformation; wherein the comparative example 11 methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber vinyl content is adjusted to 0.1mol%, the vulcanizer is adjusted to 0.4 parts, the degree of crosslinking after vulcanization is insufficient, the silicone tube has poor temperature resistance, flow elongation deformation occurs during 232℃×168h aging test, and melting deformation occurs during 430℃×0.5s tin immersion process; and the comparative example 12 methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber vinyl content is adjusted to 1.5mol%, the vulcanizer is adjusted to 2 parts, due to the high vinyl content and excessive number of vulcanizers, the rubber is scorched during the preparation process, that is, premature vulcanization and deformation, and normal tube extrusion is impossible.

[0232] Application Examples

[0233] Application of ultra-thin wall silicone tube in small transformers.

[0234] The internal wiring harness structure of a small transformer is as follows Figure 5 In the small transformer structure, the wire harness 1-3 needs to be wound around the core frame 1-1 to form a coil (OD = 1.8mm-2.5mm), and the wire harness extension wire outlet 1-3-1 needs to be bent during the manufacturing process, and the wire harness is covered with an insulating sleeve 1-2.

[0235] The ultra-thin wall silicone tubes of Examples 1 to 18 are applied to Figure 5The small transformer structure shown. The ultra-thin wall silicone tube of Example 1-Example 18 has good flame retardant and temperature resistance, and can meet the temperature resistance, thin wall (0.15mm) and flame retardant requirements of small structures. However, conventional PE / EVA pipes are difficult to meet the requirements of use temperature, flame retardant performance, etc. The ultra-thin wall silicone tube of Example 1-Example 18 has a higher elongation at break (≥200%), and no cracking is observed during the process. However, the elongation at break of ultra-thin wall tubes made of existing PEEK, PI, and PPS materials often does not reach 150%, and cracks often appear during the winding process. In addition, after the winding is completed in the process, the wire harness extension wire outlet 1-3-1 needs to undergo a tin immersion process step. At this time, one end of the catheter needs to be in contact with the tin liquid at a temperature of up to 430°C for a short time (0.5s). The ultra-thin wall silicone tubes of Examples 1 to 18 can meet the requirements of the tinning process steps, and the tubes have the performance of resisting instantaneous high temperature impact, no deformation, no melting, and no cracking. However, the existing pipes made of PEI and PPSU materials will melt and deform when in contact.

[0236] In addition, the ultra-thin-wall silicone tubes provided in Examples 1 to 18 have a suitable hardness, and during the assembly of the casing and the wiring harness, there will be no rebound or winding caused by the pipeline being too soft. However, when a vulcanized silicone tube with a Shore A hardness of 75 degrees is used for assembly, Figure 6 The phenomenon of coiled pipes shown in the figure causes the equipment to get stuck and needs to be disassembled or cleaned, affecting production efficiency.

[0237] In summary, the present invention illustrates through preferred embodiments that the mechanical, hardness, temperature resistance, flame retardancy and other properties of the silicone rubber composition are optimized by means of poly(etherimide-siloxane) copolymer, halogen-free flame retardant, vulcanizing agent, etc., so as to meet the replacement requirements of PTFE insulating sleeves in the field of small transformers and solve the drawbacks of PFAS FREE replacement technology in this field.

[0238] Although the present invention has been described with reference to the embodiments, it will be appreciated by those skilled in the art that various changes may be made and elements thereof may be replaced with equivalents without departing from the scope of the invention. In addition, various changes may be made to adapt specific circumstances or materials to the teachings of the present invention without departing from the essential scope of the present invention. Therefore, it is desirable that the present invention is not limited to the specific embodiments disclosed as the best mode considered for completing the present invention, but the present invention will include all embodiments falling within the scope of the appended claims.

Claims

1. An ultra-thin wall silicone tube for a transformer, characterized in that: The components include the following by weight: 100 parts of silicone rubber composition, 0.8-1.2 parts of vulcanizing agent, 0.3-1.0 parts of lubricant, 5-10 parts of halogen-free flame retardant, 20-30 parts of structural regulator, 0.4-0.6 parts of surfactant and 0.2-0.5 parts of carbon black; The silicone rubber composition is composed of methyl vinyl silicone rubber and methyl phenyl vinyl silicone rubber, the structural regulator is a poly(etherimide-siloxane) copolymer; and the Shore A hardness of the silicone rubber composition is 70-80 degrees.

2. The ultra-thin wall silicone tube according to claim 1, characterized in that: The vinyl content of the methyl vinyl silicone rubber is 0.4 mol%-1 mol%; the vinyl content of the methyl phenyl vinyl silicone rubber is 0.4 mol%-1 mol% and the phenyl content is 20 mol%-34 mol%.

3. The ultra-thin wall silicone tube according to claim 1, characterized in that: The Shore A hardness of the methyl vinyl silicone rubber is 70-80 degrees, and the Shore A hardness of the methyl phenyl vinyl silicone rubber is 70-80 degrees; the weight percentage of the methyl vinyl silicone rubber in the silicone rubber composition is 60%-75%.

4. The ultra-thin wall silicone tube according to claim 1, characterized in that: The vulcanizing agent is a two-component platinum vulcanizing agent; the lubricant is selected from at least one of hydroxy silicone oil, diphenylsilanediol, and methylphenyldiethoxysilane; the halogen-free flame retardant is selected from at least one of melamine cyanurate, melamine pyrophosphate, and diethylaluminum phosphinate; and the surfactant is a silane coupling agent.

5. The ultra-thin wall silicone tube according to claim 4, characterized in that: The silane coupling agent is at least one of γ-glycidylpropyltrimethoxysilane and hexamethyldisilazane.

6. The ultra-thin wall silicone tube according to claim 1, characterized in that: The poly(etherimide-siloxane) copolymer consists of polyetherimide block units and polysiloxane block units, and the weight percentage of the polysiloxane block units in the poly(etherimide-siloxane) copolymer is 10%-34%.

7. The ultra-thin wall silicone tube according to claim 1, characterized in that: The poly(etherimide-siloxane) copolymer is a poly(etherimide-siloxane) copolymer powder, and the particle size D90 of the poly(etherimide-siloxane) copolymer powder is less than or equal to 10 μm; the halogen-free flame retardant is a halogen-free flame retardant powder, and the D90 of the halogen-free flame retardant powder is 30-100 nm.

8. The ultra-thin wall silicone tube according to claim 1, characterized in that: The carbon black is N series carbon black; the wall thickness of the ultra-thin wall silicone tube is 0.1-0.15 mm, and the inner diameter of the ultra-thin wall silicone tube is 1.0-2.0 mm.

9. The method for preparing the ultra-thin-wall silicone tube according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing the structure regulator and the surfactant in the formula amount, and letting it stand to obtain a modified structure agent; S2, mixing the silicone rubber composition, lubricant, halogen-free flame retardant, carbon black and the modified structural agent obtained in step S1, and letting it stand at room temperature to obtain a silicone rubber mixture; S3, mixing the silicone rubber mixture obtained in step S2 with a vulcanizer of a formula amount, refining and thinning to obtain a silicone rubber mixture; S4, cold-extrude and bake the silicone rubber mixture obtained in step S3 to obtain an ultra-thin-wall silicone tube.

10. Use of the ultra-thin-wall silicone tube according to any one of claims 1 to 8 or the ultra-thin-wall silicone tube prepared by the preparation method according to claim 9 in a transformer.

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