Ethylene-propylene-diene monomer insulating glue for wires and cables and preparation method thereof
By using a liquid mixing system and a segmented curing process, the problems of long production processes and low efficiency in traditional wire and cable insulation adhesive production have been solved. This has enabled one-time molding of complex-shaped products and improved product performance, reduced production costs, and met the application needs of wires and cables.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HUBEI DELE ELECTRIC POWER TECH CO LTD
- Filing Date
- 2026-02-12
- Publication Date
- 2026-04-24
AI Technical Summary
Traditional wire and cable insulation adhesive production processes are lengthy, inefficient, and require large equipment investments. It is difficult to achieve one-time molding of complex-shaped products, and product quality fluctuates greatly. It is also difficult to accurately control the distribution of molecular structure and functional fillers, resulting in high costs and limiting its widespread application.
Using a liquid mixing system, liquid EPDM raw rubber is used as the main raw material, combined with mullite powder and other components. Through a segmented curing process, complex-shaped products can be formed in one step. Functional fillers are precisely and uniformly incorporated during the liquid mixing process to eliminate air bubbles and delamination defects, forming a dense and gapless insulating layer.
It reduces production costs, improves product performance and production efficiency, enables flexible design of complex-shaped products, and meets the application needs of wires and cables.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrical wire and cable insulation adhesive technology, and more specifically, relates to an EPDM insulating adhesive for electrical wires and cables and its preparation method. Background Technology
[0002] Ethylene propylene diene monomer (EPDM) insulating rubber is a rubber material synthesized by adding certain chemical reagents to EPDM raw rubber. It has excellent heat resistance, aging resistance, and corrosion resistance, and also has a high volume resistivity. Therefore, it is widely used in the field of wire and cable for the manufacture of insulation layers for special cables.
[0003] Traditional wire and cable insulation adhesive manufacturing processes require multiple steps, including internal mixing and open milling, resulting in a long production flow, low efficiency, and difficulty in precisely controlling process parameters at each stage, leading to significant fluctuations in product quality. Furthermore, traditional processes necessitate the use of large equipment such as heavy-duty internal mixers and open mills, resulting in high investment costs, high energy consumption, and difficulty in achieving one-step molding of complex shapes. On the other hand, traditional solid-state mixing processes struggle to achieve complete and uniform dispersion of fillers and are prone to introducing defects such as air bubbles and delamination, affecting insulation performance and electrical reliability. Under solid-state processing conditions, it is difficult to precisely control the distribution of molecular structure and functional fillers, limiting further improvements in material performance and the customization of complex-shaped products.
[0004] The long production process, high energy consumption, and large equipment investment result in high production costs for wire and cable insulation adhesives, limiting their widespread application in some fields. Furthermore, traditional wire and cable insulation adhesives generally use solid EPDM rubber as a raw material, and the addition of solid EPDM rubber and expensive silica is relatively high, leading to a high overall production cost and hindering companies' cost-reduction and efficiency-enhancing production strategies. Summary of the Invention
[0005] The purpose of this invention is to provide an EPDM insulating adhesive for wires and cables and a preparation method thereof. This method has a short production process and high efficiency; the preparation process does not require heavy equipment, and the use of a liquid mixing system can be used to pour complex molds, allowing for flexible product design; the liquid mixing system can accurately and uniformly incorporate various functional fillers, resulting in high structural uniformity, effectively eliminating defects such as bubbles and delamination, forming a dense and gapless insulating layer, improving the performance of the prepared product and reducing production costs.
[0006] To achieve the above objectives, a first aspect of the present invention provides an EPDM insulating adhesive for wires and cables, which is composed of the following raw materials in parts by weight: Liquid EPDM raw rubber, 37.0-39.0 parts; Mullite powder 38.0-39.0 parts; 5.0-6.0 parts of silica; Paraffin oil 7.0-8.0 parts; Zinc oxide 1.0-2.0 parts; Stearic acid 1.0-2.0 parts; Carbon black 1.0-2.0 parts; 1.0-2.0 parts of titanium dioxide; 0.1-0.3 parts of coupling agent; Anti-aging agent 0.3-0.7 parts; 1.0-2.0 parts of vulcanizing agent; 1.0-2.0 parts of crosslinking agent or 2.0-4.0 parts of vulcanization accelerator.
[0007] Furthermore, it contains the crosslinking agent, wherein the crosslinking agent is triallyl isocyanurate (TAIC), and the vulcanizing agent is dicumyl peroxide (DCP).
[0008] Further, it contains the vulcanization accelerator, which is composed of 1.0-2.0 parts of 2-mercaptobenzothiazole and 1.0-2.0 parts of tetrabenzylthiuram disulfide, and the vulcanizing agent is sulfur.
[0009] Furthermore, the coupling agent is 2-mercaptoethyltriethoxysilane.
[0010] Furthermore, the anti-aging agent is composed of 0.2-0.4 parts of N-isopropyl-N-phenyl-p-phenylenediamine and 0.1-0.3 parts of dibenzylhydroxylamine.
[0011] Furthermore, the molecular weight of the liquid EPDM raw rubber is 50,000 to 100,000.
[0012] A second aspect of the present invention provides a method for preparing EPDM insulating adhesive for wires and cables as described in any of the preceding claims, comprising the following steps: Stearic acid, zinc oxide, silica, and coupling agent are mixed evenly to obtain a mixture; Liquid EPDM raw rubber was added to a planetary mixer and heated to 40-60°C. During the mixing process, the mixture, N-isopropyl-N-phenyl-p-phenylenediamine, and dibenzylhydroxylamine were added and stirred until homogeneous to obtain the first liquid mixture system. Carbon black, mullite powder, titanium dioxide, and paraffin oil are added to the first liquid mixture system, and the air bubbles are removed by vacuuming to obtain the second liquid mixture system. Cool the temperature to 30~40℃, add vulcanizing agent and crosslinking agent or vulcanization accelerator to the second liquid mixture, stir evenly, remove bubbles by vacuuming, and obtain the third liquid mixture. The third liquid mixture is poured into a mold and cured in stages in three heating phases within the range of 80-160°C.
[0013] Furthermore, during the preparation of the first liquid mixture system and the third liquid mixture system, the stirring speed is 300~500 r / min; during the preparation of the second liquid mixture system, the stirring speed is 800~1200 r / min.
[0014] Further, the crosslinking agent is triallyl isocyanurate, the vulcanizing agent is dicumyl peroxide, and the segmented curing includes the following steps: First, heat to 80-120℃ for pre-curing for 1 hour; then heat to 120-140℃ for primary curing for 1-2 hours; finally, heat to 150-160℃ for post-curing for 1 hour.
[0015] Further, the vulcanization accelerator is composed of 2-mercaptobenzothiazole and tetrabenzylthiuram disulfide, the vulcanizing agent is sulfur, and the segmented curing includes the following steps: First, heat to 80-120℃ for pre-curing for 1 hour; then heat to 120-140℃ for primary curing for 1-2 hours; finally, heat to 150-160℃ for post-curing for 1 hour.
[0016] Compared with the prior art, the present invention has the following technical effects: The present invention discloses a raw material formulation for EPDM insulating adhesive for wires and cables, using liquid EPDM raw rubber as the main raw material. On the one hand, compared with traditional solid EPDM rubber as raw material, liquid EPDM raw rubber has a lower raw material cost, which is conducive to reducing production costs. On the other hand, it allows the raw material mixing system to be a flowing liquid mixing system before curing, which is conducive to the one-time molding of complex-shaped products and flexible product shape design. Furthermore, the liquid mixing system can accurately and uniformly incorporate various functional fillers, resulting in products with high structural uniformity and effectively eliminating defects such as bubbles and delamination, forming a dense and gapless insulating layer and improving the performance of the prepared products. Furthermore, the proportion of liquid EPDM raw rubber in the raw material formula of this invention is relatively low, accounting for only about 37-39% of the total formula mass, and the proportion of silica is also low, at about 5-6%, which can reduce the raw material production cost. The raw material formula of this invention uses a large amount of inexpensive mullite powder. Since mullite powder has strong fire resistance, it can improve the fire resistance of the prepared EPDM insulating adhesive while reducing the raw material production cost, which is beneficial to its application performance in wires and cables.
[0017] The present invention discloses a method for preparing EPDM insulating adhesive for wires and cables. By using liquid EPDM raw rubber as the main raw material, the raw material mixture remains in a flowing liquid state before curing, facilitating the one-time molding of complex-shaped products and allowing for flexible product design. Furthermore, the liquid mixture system allows for the precise and uniform incorporation of various functional fillers, resulting in highly uniform product structure. It also effectively eliminates defects such as bubbles and delamination through vacuum degassing, forming a dense, gapless insulating layer and improving product performance. In addition, the preparation method of the present invention employs segmented curing in three heating stages, which improves degassing efficiency, reduces delamination defects, and forms an even denser, gapless insulating layer, further enhancing the performance of the prepared product.
[0018] The present invention provides a method for preparing EPDM insulating adhesive for wires and cables. The production process requires no heavy equipment, is simple and efficient, and features easily controllable, staged curing temperature control, significantly improving production efficiency and reducing production costs. Furthermore, the EPDM insulating adhesive prepared by this invention meets national standards for hardness, elongation at break, and tensile strength, fulfilling the application requirements for EPDM insulating adhesives for wires and cables. Detailed Implementation
[0019] To make the technical problems, solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0020] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.
[0021] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. For example, without departing from the scope of embodiments of the invention, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.
[0022] This invention provides an EPDM insulating adhesive for wires and cables, which is composed of the following raw materials in parts by weight: Liquid EPDM raw rubber, 37.0-39.0 parts; Mullite powder 38.0-39.0 parts; 5.0-6.0 parts of silica; Paraffin oil 7.0-8.0 parts; Zinc oxide 1.0-2.0 parts; Stearic acid 1.0-2.0 parts; Carbon black 1.0-2.0 parts; 1.0-2.0 parts of titanium dioxide; 0.1-0.3 parts of coupling agent; Anti-aging agent 0.3-0.7 parts; 1.0-2.0 parts of vulcanizing agent; 1.0-2.0 parts of crosslinking agent or 2.0-4.0 parts of vulcanization accelerator.
[0023] The liquid EPDM raw rubber used in this embodiment of the invention has a molecular weight of 50,000-100,000. This allows the liquid mixture to maintain good fluidity and enables it to cure well in a short time during the subsequent curing stage. Specifically, the coupling agent is 2-mercaptoethyltriethoxysilane, and the anti-aging agent consists of 0.2-0.4 parts of N-isopropyl-N-phenyl-p-phenylenediamine and 0.1-0.3 parts of dibenzylhydroxylamine.
[0024] The EPDM insulating adhesive of this invention can be formulated using a peroxide system. In this case, the formulation contains 1.0-2.0 parts of a crosslinking agent, specifically triallyl isocyanurate (TAIC), and a vulcanizing agent, dicumyl peroxide (DCP). The peroxide system generates free radicals through the decomposition of peroxides, initiating a C / C bond crosslinking reaction between rubber molecules. The EPDM insulating adhesive prepared using the peroxide system formulation exhibits excellent temperature resistance (150-170℃), good aging resistance, low compression set, slightly lower mechanical strength, and excellent elasticity.
[0025] Furthermore, the EPDM insulating adhesive of this invention can also be formulated using a sulfide system. In this case, the formulation contains a vulcanization accelerator, which consists of 1.0-2.0 parts of 2-mercaptobenzothiazole and 1.0-2.0 parts of tetrabenzylthiuram disulfide. The vulcanizing agent is sulfur. The sulfide system undergoes a cross-linking reaction between sulfur and the double bonds in the rubber molecules. The EPDM insulating adhesive prepared using the sulfide system formulation can achieve a temperature resistance of 120-130℃, exhibits good aging resistance, large compression set, high mechanical strength, and good elasticity.
[0026] This invention also provides a method for preparing the above-mentioned EPDM insulating adhesive for wires and cables, comprising the following steps: Stearic acid, zinc oxide, silica, and coupling agent are mixed evenly to obtain a mixture; Liquid EPDM raw rubber was added to a planetary mixer and heated to 40-60°C. During the mixing process, a mixing agent, N-isopropyl-N-phenyl-p-phenylenediamine, and dibenzylhydroxylamine were added and stirred until homogeneous to obtain the first liquid mixture system. Carbon black, mullite powder, titanium dioxide, and paraffin oil are added to the first liquid mixture system, and the air bubbles are removed by vacuuming to obtain the second liquid mixture system. Cool the temperature to 30~40℃, add vulcanizing agent and crosslinking agent or vulcanization accelerator to the second liquid mixture, stir evenly, remove bubbles by vacuuming, and obtain the third liquid mixture. The third liquid mixture is poured into a mold and cured in stages in three heating phases within the range of 80-160°C.
[0027] In this embodiment of the invention, during the preparation of the first liquid mixture system and the third liquid mixture system, the stirring speed is 300~500 r / min; during the preparation of the second liquid mixture system, the stirring speed is 800~1200 r / min.
[0028] The segmented curing process in this embodiment of the invention includes the following steps: First, heat to 80-120℃ for pre-curing for 1 hour; then heat to 120-140℃ for primary curing for 1-2 hours; finally, heat to 150-160℃ for post-curing for 1 hour.
[0029] In this embodiment of the invention, pre-curing enables the mixed system to undergo an initial cross-linking reaction and further removes air bubbles from the liquid mixed system, thus avoiding the formation of pores during subsequent high-temperature curing; the main curing achieves the main cross-linking reaction of the mixed system, enabling the insulating adhesive to reach the required mechanical properties; and post-curing further improves the heat resistance, strength, and morphological stability of the insulating adhesive.
[0030] The following detailed description of an EPDM insulating adhesive for wires and cables and its preparation method, through several specific embodiments, illustrates an embodiment of the present invention.
[0031] Example 1 (Peroxide System) Weigh the raw materials of each component. First, thoroughly mix 1g of stearic acid, 2g of zinc oxide, 5g of silica, and 0.1g of coupling agent to obtain a mixture. Add 37g of liquid EPDM raw rubber to a planetary mixer, heat to 40~60℃, and stir at low speed (300~500r / min). Add the above mixture, 0.2g of N-isopropyl-N-phenyl-p-phenylenediamine, and 0.2g of dibenzylhydroxylamine in three batches, and stir for 10~15min until uniform. Add 1g of carbon black, 38g of mullite powder, 1g of titanium dioxide, and 7g of paraffin oil in batches. Increase the stirring speed to 800~1200 rpm and stir for 20~30 minutes, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Cool down to 30~40℃ to prevent scorching due to excessive temperature, then add 1g of TAIC and mix thoroughly, stirring at low speed (300~500 rpm) for 5~10 minutes until uniform. Finally, add 1g of DCP and mix thoroughly, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Then heat the mixture: first, heat to 120℃ for pre-curing for 1 hour; then heat to 140℃ for primary curing for 2 hours; finally, heat to 160℃ for post-curing for 1 hour. The heating rate is 2℃ / min.
[0032] Example 2 (Peroxide System) Weigh the raw materials of each component. First, thoroughly mix 1g of stearic acid, 2g of zinc oxide, 5g of silica, and 0.1g of coupling agent to obtain a mixture. Add 37g of liquid EPDM raw rubber to a planetary mixer, heat to 40~60℃, and stir at low speed (300~500r / min). Add the above mixture, 0.2g of N-isopropyl-N-phenyl-p-phenylenediamine, and 0.2g of dibenzylhydroxylamine in three batches, and stir for 10~15min until uniform. Add 1g of carbon black, 38g of mullite powder, 1g of titanium dioxide, and 7g of paraffin oil in batches. Increase the stirring speed to 800~1200 rpm and stir for 20~30 minutes, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Cool down to 30~40℃ to prevent scorching due to excessive temperature, then add 1g of TAIC and mix thoroughly, stirring at low speed (300~500 rpm) for 5~10 minutes until uniform. Finally, add 1g of DCP and mix thoroughly, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Then heat the mixture: first, heat to 80℃ for pre-curing for 1 hour; then heat to 120℃ for primary curing for 1 hour; finally, heat to 150℃ for post-curing for 1 hour. The heating rate is 2℃ / min.
[0033] Example 3 (Sulfide System) Weigh the raw materials of each component. First, thoroughly mix 1g of stearic acid, 2g of zinc oxide, 5g of silica, and 0.1g of coupling agent to obtain a mixture. Add 37g of liquid EPDM raw rubber to a planetary mixer, heat to 40~60℃, and stir at low speed (300~500r / min). Add the above mixture, 0.2g of N-isopropyl-N-phenyl-p-phenylenediamine, and 0.2g of dibenzylhydroxylamine in three batches, and stir for 10~15min until uniform. Add 1g of carbon black, 38g of mullite powder, 1g of titanium dioxide, and 7g of paraffin oil in batches. Increase the stirring speed to 800~1200 rpm and stir for 20~30 minutes, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Cool down to 30~40℃ to prevent scorching due to excessive temperature. Then add 1g of 2-mercaptobenzothiazole, 1g of tetrabenzylthiuram disulfide, and 2g of sulfur and mix thoroughly. Stir at low speed (300~500 rpm) for 5~10 minutes until uniform, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Then heat the mixture. First, heat to 120℃ for pre-curing for 1 hour; then heat to 140℃ for primary curing for 2 hours; finally, heat to 160℃ for post-curing for 1 hour. The heating rate is 2℃ / min.
[0034] Example 4 (Sulfide System) Weigh the raw materials of each component. First, thoroughly mix 1g of stearic acid, 2g of zinc oxide, 5g of silica, and 0.1g of coupling agent to obtain a mixture. Add 37g of liquid EPDM raw rubber to a planetary mixer, heat to 40~60℃, and stir at low speed (300~500r / min). Add the above mixture, 0.2g of N-isopropyl-N-phenyl-p-phenylenediamine, and 0.2g of dibenzylhydroxylamine in three batches, and stir for 10~15min until uniform. Add 1g of carbon black, 38g of mullite powder, 1g of titanium dioxide, and 7g of paraffin oil in batches. Increase the stirring speed to 800~1200 rpm and stir for 20~30 minutes, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Cool down to 30~40℃ to prevent scorching due to excessive temperature. Then add 1g of 2-mercaptobenzothiazole, 1g of tetrabenzylthiuram disulfide, and 2g of sulfur and mix thoroughly. Stir at low speed (300~500 rpm) for 5~10 minutes until uniform, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Then heat the mixture. First, heat to 80℃ for pre-curing for 1 hour; then heat to 120℃ for primary curing for 1 hour; finally, heat to 150℃ for post-curing for 1 hour. The heating rate is 2℃ / min.
[0035] Comparative Example 1 (Sulfide System) Weigh the raw materials of each component. First, thoroughly mix 1g of stearic acid, 2g of zinc oxide, 5g of silica, and 0.1g of coupling agent to obtain a mixture. Add 37g of liquid EPDM raw rubber to a planetary mixer, heat to 40~60℃, and stir at low speed (300~500r / min). Add the above mixture, 0.2g of N-isopropyl-N-phenyl-p-phenylenediamine, and 0.2g of dibenzylhydroxylamine in three batches, and stir for 10~15min until uniform. Add 1g of carbon black, 38g of mullite powder, 1g of titanium dioxide, and 7g of paraffin oil in batches. Increase the stirring speed to 800-1200 rpm and stir for 20-30 minutes, during which vacuum (-0.08--0.1 MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Cool down to 30-40℃ to prevent scorching due to excessive temperature. Then add 1g of 2-mercaptobenzothiazole, 1g of tetrabenzylthiuram disulfide, and 2g of sulfur and mix thoroughly. Stir at low speed (300-500 rpm) for 5-10 minutes until homogeneous, during which vacuum (-0.08--0.1 MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Then heat directly to 150℃ for 1 hour. The heating rate is 2℃ / min.
[0036] After curing, it can be seen that the prepared insulating adhesive has poor performance. During the intermediate reaction, air bubbles cannot be expelled, and it breaks easily when pulled by hand.
[0037] Comparative Example 2 (Sulfide System) Weigh the raw materials of each component. First, thoroughly mix 1g of stearic acid, 2g of zinc oxide, 5g of silica, and 0.1g of coupling agent to obtain a mixture. Add 37g of liquid EPDM raw rubber to a planetary mixer, heat to 40~60℃, and stir at low speed (300~500r / min). Add the above mixture, 0.2g of N-isopropyl-N-phenyl-p-phenylenediamine, and 0.2g of dibenzylhydroxylamine in three batches, and stir for 10~15min until uniform. Add 1g of carbon black, 38g of mullite powder, 1g of titanium dioxide, and 7g of paraffin oil in batches. Increase the stirring speed to 800~1200 rpm and stir for 20~30 minutes, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Cool down to 30~40℃ to prevent scorching due to excessive temperature. Then add 1g of 2-mercaptobenzothiazole, 1g of tetrabenzylthiuram disulfide, and 2g of sulfur and mix thoroughly. Stir at low speed (300~500 rpm) for 5~10 minutes until homogeneous, during which vacuum (-0.08~-0.1MPa) is applied to remove air bubbles and prevent air gaps in the insulation layer. Then heat to 80℃ for pre-curing for 1 hour, followed by 150℃ for post-curing for 1 hour. The heating rate is 2℃ / min.
[0038] After curing, it was found that the curing effect was much improved compared to the curing effect of Comparative Example 1, but the performance was still not up to standard. After being pulled hard by hand, cracks appeared. With continued pulling, the cracks became more and more obvious, indicating poor performance.
[0039] The hardness (HA) of the EPDM insulating adhesives prepared in Examples 1-4 of this invention was tested according to test standard VDA675202, and the elongation at break (%) and tensile strength (MPa) of the EPDM insulating adhesives prepared in Examples 1-4 of this invention were tested according to test standard DIN 53504. The test results are shown in Table 1 below.
[0040]
[0041] The EPDM insulating adhesive prepared according to the embodiments of the present invention meets the national standard requirements for hardness, elongation at break, and tensile strength, thus fulfilling the application requirements for EPDM insulating adhesives for wires and cables. Furthermore, the preparation method eliminates the need for heavy equipment, resulting in a simple and efficient production process. The staged curing temperature control is easily adjustable, significantly improving production efficiency and reducing production costs.
[0042] The preparation method of this invention uses liquid EPDM raw rubber as the main raw material. On the one hand, compared with traditional solid EPDM rubber as raw material, liquid EPDM raw rubber has a lower raw material cost, which is beneficial to reducing production costs. On the other hand, it allows the raw material mixing system to be a flowing liquid mixture before curing, which is conducive to the one-time molding of complex-shaped products and flexible product design. Furthermore, the liquid mixing system can accurately and uniformly incorporate various functional fillers, resulting in high product structural uniformity and effectively eliminating defects such as bubbles and delamination, forming a dense and gapless insulating layer, thus improving the performance of the prepared product. In addition, the weight percentage of liquid EPDM raw rubber in the raw material formula of this invention is relatively low, accounting for only about 37-39% of the total formula mass, and the weight percentage of silica is also low, at about 5-6%, which can reduce raw material production costs. The raw material formula of this invention uses a large amount of inexpensive mullite powder. Since mullite powder has strong fire resistance, it can improve the fire resistance of the prepared EPDM insulating adhesive while reducing raw material production costs, which is beneficial to its application performance in wires and cables.
[0043] Furthermore, the preparation method of this invention adopts a three-stage heating process for segmented curing, which helps to improve degassing efficiency, reduce delamination defects, form a denser and gapless insulating layer, and further improve the performance of the prepared EPDM insulating adhesive.
[0044] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.
Claims
1. A type of EPDM insulating adhesive for wires and cables, characterized in that, It consists of the following raw materials in parts by weight: Liquid EPDM raw rubber, 37.0-39.0 parts; Mullite powder 38.0-39.0 parts; 5.0-6.0 parts of silica; Paraffin oil 7.0-8.0 parts; Zinc oxide 1.0-2.0 parts; Stearic acid 1.0-2.0 parts; Carbon black 1.0-2.0 parts; 1.0-2.0 parts of titanium dioxide; 0.1-0.3 parts of coupling agent; Anti-aging agent 0.3-0.7 parts; 1.0-2.0 parts of vulcanizing agent; 1.0-2.0 parts of crosslinking agent or 2.0-4.0 parts of vulcanization accelerator.
2. The EPDM insulating adhesive for wires and cables as described in claim 1, characterized in that, It contains the crosslinking agent, wherein the crosslinking agent is triallyl isocyanurate and the vulcanizing agent is dicumyl peroxide.
3. The EPDM insulating adhesive for wires and cables as described in claim 1, characterized in that, The product contains the vulcanization accelerator, which is composed of 1.0-2.0 parts of 2-mercaptobenzothiazole and 1.0-2.0 parts of tetrabenzylthiuram disulfide, and the vulcanizing agent is sulfur.
4. The EPDM insulating adhesive for wires and cables as described in claim 1, characterized in that, The coupling agent is 2-mercaptoethyltriethoxysilane.
5. The EPDM insulating adhesive for wires and cables as described in claim 1, characterized in that, The anti-aging agent is composed of 0.2-0.4 parts of N-isopropyl-N-phenyl-p-phenylenediamine and 0.1-0.3 parts of dibenzylhydroxylamine.
6. The EPDM insulating adhesive for wires and cables as described in claim 1, characterized in that, The molecular weight of the liquid EPDM raw rubber is 50,000 to 100,000.
7. A method for preparing EPDM insulating adhesive for wires and cables as described in any one of claims 1-6, characterized in that, Includes the following steps: Stearic acid, zinc oxide, silica, and coupling agent are mixed evenly to obtain a mixture; Liquid EPDM raw rubber was added to a planetary mixer and heated to 40-60°C. During the mixing process, the mixture, N-isopropyl-N-phenyl-p-phenylenediamine, and dibenzylhydroxylamine were added and stirred until homogeneous to obtain the first liquid mixture system. Carbon black, mullite powder, titanium dioxide, and paraffin oil are added to the first liquid mixture system, and the air bubbles are removed by vacuuming to obtain the second liquid mixture system. Cool the temperature to 30~40℃, add vulcanizing agent and crosslinking agent or vulcanization accelerator to the second liquid mixture, stir evenly, remove bubbles by vacuuming, and obtain the third liquid mixture. The third liquid mixture is poured into a mold and cured in stages in three heating phases within the range of 80-160°C.
8. The method for preparing EPDM insulating adhesive for wires and cables as described in claim 7, characterized in that, During the preparation of the first liquid mixture system and the third liquid mixture system, the stirring speed is 300~500 r / min; during the preparation of the second liquid mixture system, the stirring speed is 800~1200 r / min.
9. The method for preparing EPDM insulating adhesive for wires and cables as described in claim 7, characterized in that, The crosslinking agent is triallyl isocyanurate, the vulcanizing agent is dicumyl peroxide, and the segmented curing includes the following steps: First, heat to 80-120℃ for pre-curing for 1 hour; then heat to 120-140℃ for primary curing for 1-2 hours; finally, heat to 150-160℃ for post-curing for 1 hour.
10. The method for preparing EPDM insulating adhesive for wires and cables as described in claim 7, characterized in that, The vulcanization accelerator is composed of 2-mercaptobenzothiazole and tetrabenzylthiuram disulfide, and the vulcanizing agent is sulfur. The segmented curing includes the following steps: First, heat to 80-120℃ for pre-curing for 1 hour; then heat to 120-140℃ for primary curing for 1-2 hours; finally, heat to 150-160℃ for post-curing for 1 hour.