Lightweight and flame-retardant braided hose for liquid cooling system and preparation method

Abstract

The invention discloses a light-weight and flame-retardant braided hose for a liquid cooling system and a preparation method of the light-weight and flame-retardant braided hose. The invention discloses a sizing material for preparing a braided hose for a liquid cooling system. The sizing material is prepared from the following raw materials in parts by weight: 100 parts of ethylene propylene diene monomer, 5 parts of zinc oxide, 1 part of stearic acid, 30-60 parts of carbon black, 30-50 parts of nano calcium carbonate, 15-25 parts of a plasticizer, 2-4 parts of a cross-linking agent and 1-3 parts of an assistant cross-linking agent. The invention discloses a light-weight and flame-retardant braided hose for a liquid cooling system. The braided hose sequentially comprises an inner rubber layer and a reinforcing layer from inside to outside, the rubber material of the inner rubber layer is used for preparing the braided hose for the liquid cooling system; and the reinforcing layer is formed by weaving flame-retardant polyester fibers. The braided hose disclosed by the invention has the advantages of excellent flame retardance and medium compatibility resistance, flexibility, easiness in bending, light weight and the like, has good compatibility with an ethylene glycol aqueous solution, is suitable for a liquid cooling system, and can ensure long-term, safe and reliable operation of the liquid cooling system.

Description

Technical Field

[0001] This invention belongs to the field of rubber composite material processing, and relates to a rubber compound for preparing braided hoses for liquid cooling systems, a lightweight and flame-retardant braided hose for liquid cooling systems, and a method for preparing the same. Background Technology

[0002] With the booming development of mobile internet, cloud computing, and big data, the amount of data generated by economic and social operations will expand rapidly. To cope with this surge in data value, data centers are developing rapidly. The massive data throughput and computation present unprecedented energy consumption and heat dissipation challenges for data centers, which serve as the "brains" of emerging technologies such as artificial intelligence and big data. Against this backdrop, liquid-cooled data centers, utilizing liquid cooling technology and liquid-cooled servers, have emerged, providing a new solution for data center cooling.

[0003] Liquid cooling technology, a type of liquid cooling system, is a relatively mature cooling technology that has been widely applied in aerospace, automotive, and other fields. Common media types used in liquid cooling systems include deionized water, alcohol-based solutions, fluorocarbon working fluids, mineral oil, or silicone oil. Among these, ethylene glycol aqueous solutions are the "economic first choice" for cold plate liquid cooling systems, especially suitable for medium-temperature, medium-power-density applications where environmental sensitivity is not a primary concern. Its core advantage lies in the balance between cost, thermal conductivity, and antifreeze properties, making it one of the mainstream heat transfer media due to its comprehensive performance.

[0004] In existing technologies, metal cooling pipes made of materials such as copper and aluminum, while exhibiting excellent thermal conductivity, suffer from inherent defects such as poor toughness and large bending radii. These limitations restrict the flexibility of cooling pipe layout and, due to significant thermal expansion and contraction, easily lead to stress concentration, deformation, and even leakage, thus shortening the service life of the cooling pipes and affecting the overall system performance. While PTFE (polytetrafluoroethylene) pipes possess advantages such as high temperature resistance, corrosion resistance, and good insulation, they also have some significant drawbacks. For example, under continuous load or high temperature, PTFE undergoes slow deformation (creep), which may lead to pipe loosening, seal failure, or even coolant leakage. Furthermore, its high rigidity and large bending radius make it difficult to adapt to complex piping layouts. Therefore, developing a braided flexible hose for liquid cooling systems has become an urgent technical challenge. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing cooling pipes in liquid cooling systems. Taking into account factors such as lightweighting, flexibility, and flame retardancy, this invention innovates the rubber materials and structure for hoses, providing a rubber compound for preparing cooling pipes and a braided hose for liquid cooling systems made from this rubber compound. This hose not only has excellent flame retardancy and flexibility with a small bending radius, but also exhibits good resistance to extraction from ethylene glycol aqueous solutions, resulting in a long service life and ensuring the long-term, safe, and reliable operation of the liquid cooling system.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A rubber compound for preparing braided hoses for liquid cooling systems is made from the following raw materials in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide, 1 part stearic acid, 30-60 parts carbon black, 30-50 parts nano calcium carbonate, 15-25 parts plasticizer, 2-4 parts crosslinking agent, and 1-3 parts co-crosslinking agent.

[0008] Preferably, the rubber compound used to prepare the braided hose for the liquid cooling system is made from the following raw materials in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide, 1 part stearic acid, 40 parts carbon black, 40 parts nano calcium carbonate, 20 parts plasticizer, 3 parts crosslinking agent, and 1.5 parts co-crosslinking agent.

[0009] The EPDM rubber has a Mooney viscosity ML(1+4) of 50-80 at 125°C, an ethylene content of 45-68%, and a third monomer ENB content of 3-6%.

[0010] Specifically, the EPDM rubber can be selected from EPDM rubber Keltan 5470C.

[0011] The carbon black is one or more of N234 carbon black, N330 carbon black and N660 carbon black, preferably a combination of at least one of N234 carbon black and N330 carbon black and N660 carbon black in a weight ratio of 1:3.

[0012] The plasticizer is liquid ethylene propylene rubber, which has a Mooney viscosity (ML(1+4)) of 5 to 15 at 100°C and an ethylene content of 45 to 55%.

[0013] Specifically, the liquid ethylene propylene rubber can be selected from J-0010 binary ethylene propylene rubber.

[0014] The crosslinking agent is 4,4-di(tert-butylperoxy)valerate n-butyl ester; the co-crosslinking agent is TAIC co-crosslinking agent.

[0015] A method for preparing the adhesive compound for making braided hoses for liquid cooling systems includes the following steps:

[0016] Step (1): Cool the internal mixer with water and control the temperature of the internal mixer chamber to not exceed 60°C. Add plasticizer, EPDM rubber, zinc oxide, stearic acid and nano calcium carbonate, and mix for 120±5 seconds.

[0017] Step (2): Add carbon black and mix for 6 ± 0.5 minutes;

[0018] Step (3): Add crosslinking agent and co-crosslinking agent, mix, and discharge the rubber compound after the temperature reaches 120℃;

[0019] Step (4): Transfer the rubber compound to a two-roll mill, sheet it out, and cool it to room temperature to obtain the rubber compound used to prepare braided hoses for liquid cooling systems.

[0020] A lightweight, flame-retardant braided hose for a liquid cooling system, wherein the braided hose comprises, from the inside out, an inner rubber layer and a reinforcing layer; the rubber material of the inner rubber layer is the same as that used to manufacture the braided hose for the liquid cooling system; and the reinforcing layer is woven from flame-retardant polyester fibers.

[0021] The thickness of the inner adhesive layer is 2.0 ± 0.5 mm.

[0022] The reinforcing layer is woven using flame-retardant polyester fiber in a 24-spindle 3-strand weaving method or a 36-spindle 2-strand weaving method, with a lead of 20.0–25.0 mm.

[0023] The flame-retardant polyester fiber is 1000D flame-retardant polyester fiber.

[0024] A method for preparing a lightweight, flame-retardant braided hose for a liquid cooling system includes the following steps:

[0025] Step a: Insert the soft mandrel into the rubber extruder and extrude the rubber compound used to prepare the braided hose for the liquid cooling system under vacuum conditions to obtain the inner rubber layer tube blank.

[0026] Step b: Insert the inner rubber layer tube blank into the braiding machine and braid flame-retardant polyester fibers on the outer surface of the inner rubber layer to form a reinforcing layer, thus obtaining the braided tube blank;

[0027] Step c: The braided tube blank is subjected to high-temperature steam vulcanization; the vulcanization temperature is 150℃±3℃, the vulcanization time is 60min±5min, and the vulcanization pressure is 0.50mpa±0.02MPa.

[0028] Step d: The vulcanized product is decored to obtain a braided hose.

[0029] The beneficial effects of this invention are:

[0030] The inventor innovated the rubber material and braided hose structure of the present invention. The braided hose of this invention has advantages such as flame retardancy, excellent media compatibility, flexibility, and lightweight. It also exhibits good compatibility with ethylene glycol aqueous solutions, making it suitable for liquid cooling systems. It has a long service life, ensuring the long-term, safe, and reliable operation of the liquid cooling system. Specifically:

[0031] Traditional liquid cooling rubber hoses typically have a three-layer structure, consisting of an inner rubber layer, a reinforcing layer, and an outer rubber layer from the inside out. The braided hose of this invention adopts a two-layer structure, eliminating the outer rubber layer, thereby reducing the overall wall thickness of the hose and achieving a lightweight design.

[0032] The N234 carbon black used in this invention is a high-structure, ultra-abrasion-resistant furnace black. It provides high tensile stress and abrasion resistance in EPDM rubber, exhibits good processability, and bonds tightly to the rubber. It can be used to manufacture EPDM rubber products requiring high resistance to media erosion and extraction. N660 carbon black, as a highly efficient reinforcing agent, can significantly improve the tensile strength, tear strength, and abrasion resistance of rubber products. Adding an appropriate amount of N660 carbon black can improve the internal structure of the rubber, increase intermolecular forces, and thus improve the overall strength of the rubber. This allows rubber products to better resist deformation and breakage under external forces, extending their service life. In addition, N660 carbon black also has good dispersibility and processability, enabling uniform dispersion in the rubber matrix, reducing the viscosity of the rubber, and improving its flowability. This makes the rubber easier to handle during processing, reducing energy consumption and improving production efficiency. Simultaneously, the addition of N660 carbon black can also improve the surface smoothness of the rubber, enhancing the appearance quality of the rubber products. This invention achieves both performance and processing requirements by controlling the ratio of at least one of N234 carbon black and N330 carbon black to N660 carbon black. Similarly, replacing N234 carbon black with N330 carbon black also achieves the same technical effect.

[0033] The liquid ethylene propylene rubber used in this invention has low molecular weight segments that act as "molecular chain lubricants," reducing friction between the macromolecular chains of EPDM rubber. This makes the hose less prone to stress concentration during bending, thereby improving its flexibility and fatigue resistance. Ethylene glycol aqueous solutions typically possess polarity and permeability. By introducing polar groups through the liquid ethylene propylene rubber, the compatibility between the EPDM rubber molecular chains and the ethylene glycol aqueous solution is reduced, inhibiting solvent molecules from penetrating the rubber compound and thus lowering the swelling rate. Simultaneously, the liquid ethylene propylene rubber can be uniformly distributed between the EPDM rubber macromolecular chains, forming a "micro-crosslinking network" that hinders the diffusion of ethylene glycol aqueous solution molecules, prolonging the corrosion failure cycle, improving the hose's resistance to media corrosion, and ensuring its long-term stability in an ethylene glycol aqueous solution environment.

[0034] The commonly used peroxide DCP (dicumyl peroxide) produces acetophenone upon thermal decomposition of its peroxide bonds. Acetophenone is a substance with an unpleasant odor and is harmful to human health. While BIPB (bis(tert-butylperoxyisopropylbenzene)) peroxide produces vulcanized rubber products with a milder odor, its low solubility in ethylene propylene rubber (EPR) can easily cause crystallization problems, contaminating the liquid cooling system and reducing cooling efficiency and service life. This invention uses 4,4-di(tert-butylperoxy)valerate as a crosslinking agent, thus avoiding the shortcomings of the commonly used peroxides.

[0035] The reinforcing layer of this invention is made of flame-retardant polyester fiber, which has strong chemical inertness and is not easily corroded by oils, acids, alkalis, and other media. It indirectly protects the inner rubber layer from the penetration and erosion of external chemicals, while overcoming many limitations such as the reliance on imports and high costs associated with aramid and vinylon fibers. By using polyester fibers and a braided structure, the hose's resistance to collapse and its flexibility are ensured, making it suitable for applications with small bending radii, while significantly improving the overall performance and physical and mechanical properties of the hose. Furthermore, the use of flame-retardant polyester fiber effectively blocks external high temperatures from corroding the inner rubber layer of the hose. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the lightweight, flame-retardant braided hose used in the liquid cooling system of this invention.

[0037] Figure 1 In the middle, 1-inner adhesive layer, 2-reinforcing layer. Detailed Implementation

[0038] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Take, for example, the production of a braided hose for a liquid cooling system with an inner diameter × outer diameter of 6.0±0.4mm × 11.0±0.5mm.

[0040] Example 1

[0041] like Figure 1 As shown, a lightweight, flame-retardant braided hose for a liquid cooling system includes, from the inside out, an inner rubber layer 1 and a reinforcing layer 2.

[0042] The inner rubber layer is made from the following raw materials in parts by weight: 100 parts EPDM rubber Keltan 5470C, 5 parts zinc oxide, 1 part stearic acid, 10 parts N234 carbon black, 30 parts N660 carbon black, 40 parts nano calcium carbonate, 20 parts J-0010 EPDM rubber, 3 parts 4,4-di(tert-butylperoxy)valerate n-butyl ester (crosslinking agent), and 1.5 parts co-crosslinking agent TAIC. The preparation method of the inner rubber layer material is as follows:

[0043] Step (1): Cool the internal mixer with water and control the temperature of the internal mixer chamber to not exceed 60℃. Add J-0010 ethylene propylene diene monomer (EPDM) rubber, Keltan 5470C EPDM rubber (base material), zinc oxide, stearic acid and nano calcium carbonate, and mix for 120 seconds.

[0044] Step (2): Add N234 carbon black and N660 carbon black, and mix for 6 minutes;

[0045] Step (3): Add 4,4-di(tert-butyl peroxy)valerate and crosslinking agent TAIC, mix, and discharge the rubber compound after the temperature reaches 120℃;

[0046] Step (4): Transfer the rubber compound to the open mill, sheet it out in thin sheets, and cool it to room temperature to obtain EPDM rubber material, which is the inner rubber layer.

[0047] The preparation method of the braided hose in this embodiment is as follows:

[0048] Step a: Feed the inner rubber layer material into the feed port of the rubber extruder, insert the soft mandrel into the rubber extruder, and extrude the inner rubber layer material under a pressure of less than -0.06MPa (gauge pressure) to obtain an inner rubber layer tube blank with an inner rubber layer thickness of 2.0mm.

[0049] Step b: Insert the inner rubber layer tube blank into the braiding machine and braid flame-retardant polyester fiber (SFR1108 flame-retardant polyester industrial fiber, Zhejiang Youfu High-tech Fiber Co., Ltd.) on the outer surface of the inner rubber layer to form a reinforcing layer. The braiding method is to use 24 spindles of 3 strands of flame-retardant polyester yarn to braid the tube blank with a lead of 20.0 mm.

[0050] Step c: Set the vulcanization temperature to 150℃±3℃, the vulcanization time to 60min±5min, and the vulcanization pressure to 0.50mpa±0.02MPa. Perform high-temperature steam vulcanization on the braided tube blank.

[0051] Step d: The vulcanized product is decored to obtain a braided hose.

[0052] Example 2

[0053] The structure and preparation method of the braided hose for the liquid cooling system in this embodiment are the same as those in Embodiment 1, except that the lead of the reinforcing layer braid is adjusted to 25.0 mm.

[0054] Example 3

[0055] The structure and preparation method of the braided hose for the liquid cooling system in this embodiment are the same as those in Embodiment 1, except that the braiding method of the reinforcing layer is adjusted to 36 spindles and 2 strands.

[0056] Comparative Example 1

[0057] Compared with Example 1, the reinforcing layer of Comparative Example 1 uses 1000D polyester fiber, and the rest is the same as that of Example 1.

[0058] Comparative Example 2

[0059] Compared with Example 1, the reinforcing layer of Comparative Example 2 uses 1000D glass fiber, and the rest is the same as that of Example 1.

[0060] Comparative Example 3

[0061] Compared with Example 1, the J-0010 ethylene propylene diene monomer (EPDM) rubber used to prepare the inner rubber layer was replaced with an equal amount of paraffin oil 2280, and the rest was the same as in Example 1.

[0062] The performance of the braided hoses of Examples 1-3 and Comparative Examples 1-3 is shown in Table 1.

[0063] Table 1. Performance of Braided Hose

[0064]

[0065]

[0066] Note: The absence of a year after the standard number indicates the latest version is being used; compatibility testing uses an ethylene glycol aqueous solution (ethylene glycol:water volume ratio = 1:1).

[0067] Compared to the braided hose of Example 1, the reinforcing layer of the braided hose in Comparative Example 1 was replaced with non-flame-retardant polyester fiber. Although its bending resistance and bending resistance tests met the requirements, the braided hose lacked sufficient flame retardancy and could be rapidly ignited due to its inability to withstand initial high temperatures, potentially triggering a chain reaction from localized fires to large-scale safety accidents. Compared to the braided hose of Example 1, the reinforcing layer of the braided hose in Comparative Example 2 was replaced with glass fiber. Glass fiber has higher rigidity than polyester fiber and is less adaptable to bending deformation, resulting in higher internal bending stress. This high stress accumulates continuously, making the hose more prone to premature failure due to "stress accumulation + brittle fracture". The inner layer rubber of the braided hose in Comparative Example 3 was made of EPDM rubber with a sulfur vulcanization system. After a compatibility test with ethylene glycol aqueous solution, the rubber compound became turbid, which would contaminate the cold plate liquid cooling system. At the same time, cracks appeared on the inner surface of the hose after an electrochemical corrosion test, reducing its service life.

[0068] In summary, the lightweight, flame-retardant braided hose for the liquid cooling system of this invention has the characteristics of excellent media compatibility, flexibility and bendability, and long service life, which solves the problem of inconvenient installation caused by the limited space around the liquid cooling system.

[0069] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the scope of protection of the present invention in any way, and any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rubber compound for preparing braided hoses for liquid cooling systems, characterized in that: It is made from the following raw materials in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide, 1 part stearic acid, 30-60 parts carbon black, 30-50 parts nano calcium carbonate, 15-25 parts plasticizer, 2-4 parts crosslinking agent, and 1-3 parts co-crosslinking agent.

2. The adhesive compound for preparing braided hoses for liquid cooling systems according to claim 1, characterized in that: It is made from the following raw materials in parts by weight: 100 parts EPDM rubber, 5 parts zinc oxide, 1 part stearic acid, 40 parts carbon black, 40 parts nano calcium carbonate, 20 parts plasticizer, 3 parts crosslinking agent, and 1.5 parts co-crosslinking agent.

3. The adhesive compound for preparing braided hoses for liquid cooling systems according to claim 1 or 2, characterized in that: The EPDM rubber has a Mooney viscosity ML(1+4) of 50-80 at 125°C, an ethylene content of 45-68%, and a third monomer ENB content of 3-6%.

4. The adhesive compound for preparing braided hoses for liquid cooling systems according to claim 1 or 2, characterized in that: The carbon black is one or more of N234 carbon black, N330 carbon black and N660 carbon black, preferably a combination of N234 carbon black and N660 carbon black in a weight ratio of 1:

3.

5. The adhesive compound for preparing braided hoses for liquid cooling systems according to claim 1 or 2, characterized in that: The plasticizer is liquid ethylene propylene rubber, which has a Mooney viscosity (ML(1+4)) of 5 to 15 at 100°C and an ethylene content of 45 to 55%.

6. The adhesive compound for preparing braided hoses for liquid cooling systems according to claim 1 or 2, characterized in that: The crosslinking agent is 4,4-di(tert-butylperoxy)valerate n-butyl ester; the co-crosslinking agent is TAIC co-crosslinking agent.

7. A lightweight, flame-retardant braided hose for a liquid cooling system, characterized in that: The braided hose comprises, from the inside out, an inner rubber layer and a reinforcing layer; the rubber material of the inner rubber layer is the rubber material for preparing braided hoses for liquid cooling systems as described in claim 1; the reinforcing layer is woven from flame-retardant polyester fibers.

8. The lightweight, flame-retardant braided hose for a liquid cooling system according to claim 7, characterized in that: The thickness of the inner adhesive layer is 2.0 ± 0.5 mm.

9. The lightweight, flame-retardant braided hose for a liquid cooling system according to claim 7, characterized in that: The reinforcing layer is woven using flame-retardant polyester fiber in a 24-spindle 3-strand weaving method or a 36-spindle 2-strand weaving method, with a lead of 20.0–25.0 mm.

10. A method for preparing a lightweight, flame-retardant braided hose for a liquid cooling system as described in claim 7, characterized in that: Includes the following steps: Step a: Insert the soft mandrel into the rubber extruder and extrude the rubber compound used to prepare the braided hose for the liquid cooling system under vacuum conditions to obtain the inner rubber layer tube blank. Step b: Insert the inner rubber layer tube blank into the braiding machine and braid flame-retardant polyester fibers on the outer surface of the inner rubber layer to form a reinforcing layer, thus obtaining the braided tube blank; Step c: The braided tube blank is subjected to high-temperature steam vulcanization; the vulcanization temperature is 150℃±3℃, the vulcanization time is 60min±5min, and the vulcanization pressure is 0.50mpa±0.02MPa. Step d: The vulcanized product is decored to obtain a braided hose.

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