Double-layer cold shrink tubing and preparation method and use thereof

Abstract

The present invention provides a double-layer cold shrink sleeve and a preparation method and use thereof. An EPDM cold shrink tube is used to make the double-layer cold shrink sleeve have excellent wear resistance and scratch resistance. In addition, the inner diameter matching design between the EPDM cold shrink tube and the silicone cold shrink tube solves the problem of gaps caused by the difference in shrinkage between the EPDM cold shrink tube and the silicone cold shrink tube. When in use, the double-layer cold shrink sleeve can be directly installed on a cable connector, a power cable connector or other types of cable connectors, and the installation can be completed by pulling out a supporting tube. The double-layer cold shrink sleeve can provide a durable and reliable waterproof seal for connectors or connectors that need to be protected in extremely cold, extremely hot, extremely humid, plateau and salt spray environments.

Description

Technical Field

[0001] The invention belongs to the technical field of waterproof sealing, and in particular relates to a double-layer cold shrink sleeve and a preparation method and application thereof. Background Art

[0002] At present, the waterproof sealing of communication connectors, power cables and various cable joints in the fields of communication, power, rail transportation and petrochemical industry mostly adopts cold shrink tubing solutions. The main materials of cold shrink tubing on the market are silicone rubber materials and EPDM rubber materials. The structures of cold shrink tubing prepared from these two materials mainly include single-layer silicone cold shrink tubing, built-in silicone cement cold shrink tubing, single-layer EPDM cold shrink tubing and a double-layer EPDM cold shrink tubing with built-in silicone tube as mentioned in Chinese patent documents CN205791324U and CN104610664A.

[0003] However, the above cold shrink sleeves with different structures still have the following defects:

[0004] 1. Single-layer silicone cold shrink tubing has obvious advantages in retraction, but due to its poor physical and mechanical properties, its tear resistance, wear resistance and puncture resistance are very poor. It will break when it is bumped during the installation process or hit in hail weather, which will eventually make the product invalid and fail to meet the waterproof sealing requirements;

[0005] 2. The built-in silicone cement cold shrink sleeve is a single-layer silicone cold shrink sleeve with a layer of uncured silicone rubber cement built in. It is better than the single-layer silicone cold shrink sleeve in terms of waterproof sealing performance, but it also has the defects mentioned in the above point 1. In addition, the built-in silicone cement is in a non-cured state, and aging phenomena such as cracking will occur over time, affecting the waterproof sealing performance of the product;

[0006] 3. The single-layer EPDM cold shrink tubing has obvious advantages over silicone rubber in terms of wear resistance and puncture resistance, but its shrinkage performance is worse than that of silicone cold shrink tubing in high and low temperature environments, and its storage stability is also poor. As time goes by, the shrinkage of the EPDM cold shrink tubing will be lost in the expanded state, which will eventually affect the waterproof sealing performance of the product;

[0007] 4. A double-layer cold shrink tubing mentioned in Chinese patent documents CN205791324U and CN104610664A is obtained by expanding a section of silicone tube and then expanding a layer of EPDM rubber tube, and there is a certain reserved distance between the silicone tube and the EPDM rubber tube. The double-layer cold shrink tubing using this method will have obvious gaps between the silicone layer and the EPDM rubber layer after installation due to the great difference in the shrinkage of the EPDM rubber tube and the silicone tube. Water is easily accumulated in the gap, which ultimately affects the waterproof sealing performance of the product. Summary of the invention

[0008] In order to improve the deficiencies of the prior art, the present invention provides a double-layer cold shrink sleeve, which includes a support tube, a silicone cold shrink tube and an ethylene propylene rubber cold shrink tube; the silicone cold shrink tube is sleeved on the outer surface of the support tube, and the ethylene propylene rubber cold shrink tube is sleeved on the outer surface of the silicone cold shrink tube; and an adhesive is filled between the outer surface of the silicone cold shrink tube and the inner surface of the ethylene propylene rubber cold shrink tube to form an adhesive interface layer;

[0009] The ratio k of the inner diameter of the EPDM cold shrink tube to the inner diameter of the silicone cold shrink tube satisfies 1≤k≤1.5; the silicone cold shrink tube and the EPDM rubber tube have the same length. In other words, the inner diameter of the EPDM cold shrink tube is greater than the inner diameter of the silicone cold shrink tube, and the gap between the two is filled by the wall of the silicone cold shrink tube with a certain thickness.

[0010] According to the present invention, the ratio k of the inner diameter of the EPDM cold shrink tube to the inner diameter of the silicone cold shrink tube satisfies 1≤k≤1.5, for example, k is 1.1, 1.2, 1.3, or 1.4.

[0011] According to the present invention, the EPDM cold shrink tube and the silicone cold shrink tube themselves have a tube wall with a thickness, and the inner diameter refers to the diameter between the inner walls of the tube wall.

[0012] According to the present invention, when the silicone cold shrink tube and the EPDM rubber tube have the same length and the inner diameter ratio meets the above coefficient K value requirement, the double-layer tube prepared in this way can achieve the technical effect of simultaneous shrinkage without generating any gaps.

[0013] According to the present invention, the support tube is formed by surrounding a support wire (for example, a support wire), and the support tube is a cylindrical tube body; a draw rope connected to the support wire is left inside the support tube, or the support wire is directly used as the draw rope.

[0014] According to the present invention, the outer surface of the silicone cold shrink tube is modified by a surface modifier and then filled with an adhesive. The reason for selecting the surface treatment is to activate the outer surface of the silicone cold shrink tube and improve the bonding strength of the adhesive.

[0015] According to the present invention, the surface modification is selected from vinyl silane, amino silane, methacryloxy silane and the like.

[0016] According to the present invention, the silicone cold shrink tube is made of silicone.

[0017] According to the present invention, the thickness of the silicone cold shrink tube itself can be 1-10 mm, for example, 2-9 mm, 3-8 mm, 4-7 mm, 5-6 mm. The thickness here refers to the unexpanded silicone cold shrink tube, that is, the thickness of the silicone cold shrink tube itself.

[0018] According to the present invention, the thickness of the adhesive interface layer is 0.05-2 mm.

[0019] According to the present invention, the adhesive is selected from at least one of styrene-butadiene rubber adhesive, chloroprene rubber adhesive, isocyanate adhesive and epoxy adhesive.

[0020] According to the present invention, the thickness of the EPDM cold shrink tube itself can be 1-10 mm, for example, 2-9 mm, 3-8 mm, 4-7 mm, 5-6 mm. The thickness here refers to the unexpanded EPDM cold shrink tube, that is, the thickness of the tube itself.

[0021] According to the present invention, the expansion ratio of the silicone cold shrink tube can be 1 to 5 times, for example, 1.5 to 4.5 times, 2 to 4 times, 2.5 to 3.5 times. The silicone cold shrink tube is preferably a silicone cold shrink tube of model KC92 produced by Shenzhen Kexinyuan New Materials Co., Ltd. The expansion ratio here refers to the ratio of the outer diameter of the support tube to the inner diameter of the unexpanded silicone cold shrink tube.

[0022] According to the present invention, the expansion ratio of the EPDM cold shrink tube can be 1 to 4.5 times, for example, 1.5 to 4 times, 2 to 3.5 times, or 2.5 to 3 times. The EPDM cold shrink tube is preferably an EPDM cold shrink tube of model KC96 produced by Shenzhen Kexinyuan New Materials Co., Ltd. The ratio of the outer diameter of the support tube to the inner diameter of the unexpanded EPDM cold shrink tube is referred to herein.

[0023] The present invention also provides a method for preparing the double-layer cold shrink sleeve, comprising the following steps:

[0024] A: Evenly apply the surface treatment agent on the outer surface of the silicone cold shrink tube to perform surface treatment on the outer surface of the silicone cold shrink tube;

[0025] B: Apply the adhesive evenly on the outer surface of the silicone cold shrink tube;

[0026] C: expanding the EPDM cold shrink tube onto the silicone cold shrink tube prepared in step B above through an expander to prepare a double-layer tube with an adhesive interface layer;

[0027] D: Cut the double-layer tube prepared in step C above to the required length, and ensure that the silicone cold shrink tube and the EPDM cold shrink tube have the same length;

[0028] E: The double-layer tube prepared in the above step D is expanded onto the support tube through an expander to obtain the double-layer cold shrink sleeve.

[0029] The present invention also provides the use of the double-layer cold shrink sleeve, which is used as a waterproof auxiliary material in the communication, electric power, rail transportation, petrochemical and other industries. For example, it is used for waterproof sealing protection of communication radio frequency cable connectors, power cable connectors, and various cable connectors.

[0030] Beneficial effects of the present invention:

[0031] The present invention provides a double-layer cold shrink sleeve and a preparation method and use thereof. An EPDM cold shrink tube is used to make the double-layer cold shrink sleeve have excellent wear resistance and scratch resistance. In addition, the inner diameter matching design between the EPDM cold shrink tube and the silicone cold shrink tube solves the problem of gaps caused by the difference in shrinkage between the EPDM cold shrink tube and the silicone cold shrink tube. When in use, the double-layer cold shrink sleeve can be directly installed on a cable connector, a power cable connector or other types of cable connectors, and the installation can be completed by pulling out a supporting tube. The double-layer cold shrink sleeve can provide a durable and reliable waterproof seal for connectors or connectors that need to be protected in extremely cold, extremely hot, extremely humid, plateau and salt spray environments.

[0032] The double-layer cold shrink sleeve of the present invention has good low temperature resistance, resilience and physical and mechanical properties. The double-layer cold shrink sleeve has the functions of wear resistance and waterproof sealing; the ratio k of the inner diameter of the silicone cold shrink tube to the inner diameter of the EPDM cold shrink tube should satisfy 1≤k≤1.5. The double-layer cold shrink sleeve that satisfies this ratio can solve the problem of inconsistent retraction of the EPDM cold shrink tube and the silicone cold shrink tube. The EPDM cold shrink tube retracts more slowly, and at the same time, the EPDM cold shrink tube can provide a continuous clamping force to the silicone cold shrink tube, synergistically enhancing the waterproof sealing effect and life of the silicone cold shrink tube; the silicone cold shrink tube and the EPDM cold shrink tube have the same length, and such a setting can well avoid the influence of waterproof problems and wear problems on product performance (when the length of the EPDM cold shrink tube is longer than that of the silicone cold shrink tube, gaps will be generated at both ends, resulting in water accumulation, thereby affecting the waterproof performance of the product; at the same time, it can well avoid that when the length of the EPDM cold shrink tube is shorter than that of the silicone cold shrink tube, the wear resistance and puncture resistance of the part not covered by the EPDM cold shrink tube after the product is installed will decrease). The waterproof grade of the double-layer cold shrink tubing can reach the highest IPX8 waterproof grade. Moreover, the tubing can still maintain the consistency of the inner and outer layer shrinkage performance at a low temperature below -20°C, and can still provide effective waterproof sealing protection function at low temperatures. Moreover, the introduction of the adhesive interface agent further improves the physical and mechanical properties of the double-layer cold shrink tubing.

[0033] In summary, the double-layer cold shrink sleeve provided by the present invention can widely provide waterproof sealing protection and physical protection for communication RF cable connectors, power cable joints, and various cable joints. The double-layer cold shrink sleeve utilizes the good resilience of the inner layer silicone cold shrink tube and the wear resistance and puncture resistance of the outer layer EPDM rubber cold shrink tube to provide long-lasting and reliable waterproof sealing and physical protection for connectors or joints that need protection in extremely cold, extremely hot, extremely humid, plateau and salt spray environments, thereby ensuring stable signal transmission and power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of a double-layer cold shrink sleeve according to a preferred embodiment of the present invention.

[0035] The accompanying drawings are marked as follows: 1-ethylene propylene rubber cold shrink tube, 2-silicone cold shrink tube, 3-support tube, 4-adhesive interface layer. DETAILED DESCRIPTION

[0036] The preparation method of the present invention will be described in further detail below in conjunction with specific examples. It should be understood that the following examples are only exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

[0037] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0038] The test methods or standards used in the following embodiments are: the test standard for tensile strength is ASTM D412-15a Method A; the test standard for elongation at break is ASTM D412-15a Method A; the test standard for tear strength is ASTM D624-00 (2012); the test standard for 300% tensile stress is ASTM D412-15a Method A; the test standard for waterproof grade is the IPX8 (1m, 4h) grade requirement of IEC60529.

[0039] Example 1

[0040] A: Select a silicone cold shrink tube with an inner diameter of 7mm and a thickness of 2.5mm (expansion ratio 4.5 times), and evenly apply the vinyl silane surface treatment agent on the outer surface of the silicone cold shrink tube to perform surface treatment on the outer surface of the silicone cold shrink tube;

[0041] B: Apply the styrene-butadiene rubber adhesive evenly on the outer surface of the silicone cold shrink tube;

[0042] C: Select an EPDM rubber cold shrink tube with an inner diameter of 8 mm and a thickness of 2.5 mm (expansion ratio of 4.5 times), and expand the EPDM rubber cold shrink tube onto the silicone cold shrink tube prepared in step B above through an expander to prepare a double-layer tube with an adhesive interface layer;

[0043] D: Cut the double-layer tube prepared in step C above to the required length, and ensure that the silicone cold shrink tube and the EPDM cold shrink tube have the same length;

[0044] E: The double-layer tube prepared in the above step D is expanded onto the support tube through an expander, and finally a double-layer cold shrink sleeve is prepared.

[0045] The ratio k of the inner diameter of the silicone cold shrink tube to the inner diameter of the EPDM rubber cold shrink tube in the double-layer cold shrink tube prepared in Example 1 is 1.14, satisfying 1≤k≤1.5; at the same time, the silicone cold shrink tube and the EPDM rubber tube have the same length.

[0046] The double-layer cold shrink tubing prepared in Example 1 was tested, and the results were as follows:

[0047] The tensile strength is 10.14MPa; the elongation at break is 936%; the tear strength is 41N / mm; the 300% elongation stress is 1.85; and the waterproof grade is IPX8.

[0048] The double-layer cold shrink tubing prepared in the above Example 1 was placed at a low temperature of -20°C to test its shrinkage performance.

[0049] The evaluation of shrinkage performance is through visual observation. After the product shrinks, there is no obvious gap or separation between the two layers or at the end of the silicone cold shrink tube. The specific steps are to pretreat the finished product in an environment of -20℃±2℃ for 4 hours, and perform installation operations in this temperature environment. It is required to be able to be installed normally, and there is no obvious gap or separation at the two ends of the double-layer cold shrink tube. The shrinkage is basically completed within 5 minutes, and there is no obvious gap at the end of the silicone cold shrink tube (this test result is judged as passed).

[0050] The test results are: there is no obvious gap or separation at the two ends of the double-layer cold shrink tubing, the shrinkage is basically completed within 5 minutes, and there is no obvious gap between the silicone cold shrink tubing port and the cable.

[0051] Low-temperature waterproof sealing test: The specific test method is to install the double-layer cold shrink tubing to the feeder joint and other locations that require waterproofing, store the sample in a low-temperature test box for 168 hours, take it out and leave it for 4 hours, and then test it according to the IPX8 waterproof standard, immerse it in 1-meter water for 4 hours, and use a waterproof test paper built into the joint. If the test paper does not change color, it proves that the joint is not water-proof, and it is judged to have passed.

[0052] The test results show that it can still provide effective waterproof sealing protection at low temperatures.

[0053] Example 2

[0054] A: Select a silicone cold shrink tube with an inner diameter of 9 mm and a thickness of 3.0 mm (expansion ratio 4.5 times), and evenly apply the vinyl silane surface treatment agent on the outer surface of the silicone cold shrink tube to perform surface treatment on the outer surface of the silicone cold shrink tube;

[0055] B: Apply the styrene-butadiene rubber adhesive evenly on the outer surface of the silicone cold shrink tube;

[0056] C: Select an EPDM cold shrink tube with an inner diameter of 10 mm and a thickness of 3.0 mm (expansion ratio 4.5 times), and expand the EPDM cold shrink tube onto the silicone cold shrink tube prepared in step B above through an expander to prepare a double-layer tube with an adhesive interface layer;

[0057] D: Cut the double-layer tube prepared in step C above to the required length, and ensure that the silicone cold shrink tube and the EPDM cold shrink tube have the same length;

[0058] E: The double-layer tube prepared in step D is expanded onto the support tube through an expander, and finally a double-layer cold shrink sleeve is prepared.

[0059] The ratio k of the inner diameter of the silicone cold shrink tube to the inner diameter of the EPDM rubber cold shrink tube in the double-layer cold shrink tube prepared in Example 2 is 1.11, satisfying 1≤k≤1.5; at the same time, the silicone cold shrink tube and the EPDM rubber tube have the same length.

[0060] The double-layer cold shrink sleeve prepared in Example 2 was tested, and the results were as follows:

[0061] The tensile strength is 10.22MPa; the elongation at break is 913%; the tear strength is 40N / mm; the 300% elongation stress is 1.88; and the waterproof grade is IPX8.

[0062] The double-layer cold shrink tubing prepared in the above Example 2 was placed at a low temperature of -20°C to test its shrinkage performance.

[0063] The evaluation of shrinkage performance is through visual observation. After the product shrinks, there is no obvious gap or separation between the two layers or at the end of the silicone cold shrink tube. The specific steps are to pretreat the finished product in an environment of -20℃±2℃ for 4 hours, and perform installation operations in this temperature environment. It is required to be able to be installed normally, and there is no obvious gap or separation at the two ends of the double-layer cold shrink tube. The shrinkage is basically completed within 5 minutes, and there is no obvious gap at the end of the silicone cold shrink tube (this test result is judged as passed).

[0064] The test results are: there is no obvious gap or separation at the two ends of the double-layer cold shrink tubing, the shrinkage is basically completed within 5 minutes, and there is no obvious gap between the silicone cold shrink tubing port and the cable.

[0065] Low-temperature waterproof sealing test: The specific test method is to install the double-layer cold shrink tubing to the feeder joint and other locations that require waterproofing, store the sample in a low-temperature test box for 168 hours, take it out and leave it for 4 hours, and then test it according to the IPX8 waterproof standard, immerse it in 1-meter water for 4 hours, and use a waterproof test paper built into the joint. If the test paper does not change color, it proves that the joint is not water-proof, and it is judged to have passed.

[0066] The test results show that it can still provide effective waterproof sealing protection at low temperatures.

[0067] Comparative Example 1

[0068] A: Select a silicone cold shrink tube with an inner diameter of 7mm and a thickness of 2.5mm (expansion ratio 4.5 times);

[0069] B: Select an EPDM rubber cold shrink tube with an inner diameter of 8 mm and a thickness of 2.5 mm (expansion ratio 4.5 times), and expand the EPDM rubber cold shrink tube onto the silicone cold shrink tube in step A above through an expander to prepare a double-layer tube;

[0070] C: Cut the double-layer tube prepared in step B above to the required length, and ensure that the silicone cold shrink tube and the EPDM cold shrink tube have the same length;

[0071] D: The double-layer tube prepared in step C is expanded onto the support tube through an expander, and finally a double-layer cold shrink sleeve is prepared.

[0072] The tensile strength of the double-layer cold shrink tubing prepared in Comparative Example 1 is 9.1 MPa; the elongation at break is 850%; the tear strength is 35 N / mm; the 300% elongation stress is 1.67; and the waterproof grade is IPX7.

[0073] From the performance data of the double-layer cold shrinkable sleeve prepared in Example 1 and Comparative Example 1, it can be seen that the introduction of the adhesive improves the physical and mechanical properties of the double-layer cold shrinkable sleeve.

[0074] Comparative Example 2

[0075] A: Select a silicone cold shrink tube with an inner diameter of 9mm and a thickness of 3mm (expansion ratio 4.5 times);

[0076] B: Select an EPDM rubber shrink tube with an inner diameter of 10 mm and a thickness of 3 mm (expansion ratio 4.5 times), expand the EPDM rubber shrink tube onto the silicone shrink tube in step A above through an expander, and prepare a double-layer tube;

[0077] C: Cut the double-layer tube prepared in step B above to the required length, and ensure that the silicone cold shrink tube and the EPDM cold shrink tube have the same length;

[0078] D: The double-layer tube prepared in step C is expanded onto the support tube through an expander, and finally a double-layer cold shrink sleeve is prepared.

[0079] The tensile strength of the double-layer cold shrinkable sleeve prepared in Comparative Example 2 is 9.2MPa; the elongation at break is 860%; the tear strength is 35N / mm; the 300% elongation stress is 1.58; and the waterproof grade is IPX7. From the performance data of the double-layer cold shrinkable sleeve prepared in Example 2 and Comparative Example 2, the introduction of the adhesive improves the physical and mechanical properties of the double-layer cold shrinkable sleeve.

[0080] Comparative Example 3

[0081] The difference compared with Example 1 is:

[0082] The ratio of the inner diameter of the EPDM rubber tube to the inner diameter of the silicone rubber tube is k=0.86.

[0083] After the expansion of the expansion agent, the outer EPDM rubber tube cannot be sleeved on the outer surface of the silicone rubber tube. The double-layer cold shrink sleeve cannot be realized in the current production process technology.

[0084] Comparative Example 4

[0085] The difference compared with Example 1 is:

[0086] The ratio of the inner diameter of the EPDM rubber tube to the inner diameter of the silicone rubber tube is k=1.71.

[0087] The waterproof grade of this double-layer cold shrink tubing is only IPX7.

[0088] It can be seen from the above embodiments and comparative examples that the double-layer cold shrink sleeve of the present invention has good low temperature resistance, resilience and physical and mechanical properties. The double-layer cold shrink sleeve has the functions of wear resistance and waterproof sealing; the ratio k of the inner diameter of the silicone cold shrink tube to the inner diameter of the EPDM cold shrink tube should satisfy 1≤k≤1.5. The double-layer cold shrink sleeve that satisfies this ratio can solve the problem of slow shrinkage of the EPDM cold shrink tube, and at the same time enable the EPDM cold shrink tube to provide continuous clamping force to the silicone cold shrink tube, synergistically enhancing the waterproof sealing effect and life of the silicone cold shrink tube; when K>1.5, the waterproof grade of the product cannot meet IPX8, and when K<1, the product cannot be produced with the current production process technology.

[0089] The lengths of the silicone cold shrink tube and the EPDM cold shrink tube are the same. This arrangement can effectively avoid the situation where the EPDM cold shrink tube does not cover the silicone cold shrink tube due to the short length of the silicone cold shrink tube and the long length of the EPDM cold shrink tube. This will cause water to accumulate in this area, thus affecting the waterproof performance of the product. The waterproof rating of the double-layer cold shrink tube can reach the highest IPX8 waterproof rating. Moreover, the sleeve can still maintain the consistency of the retraction performance of the inner and outer layers at temperatures below -20°C, and can still provide effective waterproof sealing protection at low temperatures.

[0090] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A double-layer cold shrink tube, comprising a support tube, a silicone cold shrink tube and an EPDM cold shrink tube; the silicone cold shrink tube is sleeved on the outer surface of the support tube, and the EPDM cold shrink tube is sleeved on the outer surface of the silicone cold shrink tube; wherein, The outer surface of the silicone cold shrink tube is coated with a vinyl silane surface treatment agent, and the outer surface of the silicone cold shrink tube is surface treated, and then the styrene-butadiene rubber adhesive is coated on the outer surface of the silicone cold shrink tube, and then the ethylene-propylene rubber cold shrink tube is expanded onto the silicone cold shrink tube through an expander to prepare a double-layer cold shrink tube with an adhesive interface layer; The ratio k of the inner diameter of the EPDM rubber cold shrink tube to the inner diameter of the silicone cold shrink tube satisfies 1≤k≤1.5; the silicone cold shrink tube and the EPDM rubber tube have the same length; The expansion ratios of the silicone cold shrink tube and the EPDM cold shrink tube are the same, both of which are 4.5 times; The inner diameters of the silicone cold shrink tube and the EPDM cold shrink tube are 7mm and 8mm respectively, and the thickness of both is 2.5mm; or the inner diameters of the silicone cold shrink tube and the EPDM cold shrink tube are 9mm and 10mm respectively, and the thickness of both is 3mm.

2. The double-layer cold shrink sleeve according to claim 1, wherein: The support tube is formed by surrounding the support wire, and the support tube is a cylindrical tube body; a draw rope connected to the support wire is left inside the support tube, or the support wire is directly used as the draw rope.

3. The double-layer cold shrink sleeve according to any one of claims 1 to 2, wherein: The thickness of the adhesive interface layer is 0.05-2 mm.

4. The method for preparing the double-layer cold shrinkable sleeve according to any one of claims 1 to 3, comprising the following steps: A: Evenly apply the vinyl silane surface treatment agent on the outer surface of the silicone cold shrink tube to perform surface treatment on the outer surface of the silicone cold shrink tube; B: Apply the styrene-butadiene rubber adhesive evenly on the outer surface of the silicone cold shrink tube; C: expanding the EPDM cold shrink tube onto the silicone cold shrink tube prepared in step B above through an expander to prepare a double-layer tube with an adhesive interface layer; D: Cut the double-layer tube prepared in step C above to the required length, and ensure that the silicone cold shrink tube and the EPDM cold shrink tube have the same length; E: The double-layer tube prepared in the above step D is expanded onto the support tube through an expander to obtain the double-layer cold shrink sleeve.

5. Use of the double-layer cold shrink tubing according to any one of claims 1 to 3, which is used as a waterproof auxiliary material in the communication, electric power, rail transportation, and petrochemical industries.

6. The use according to claim 5 is used for waterproof sealing protection of communication radio frequency cable connectors and power cable joints.

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