A self-repairing halogen-free flame-retardant polyurethane material for robot cables and a preparation method thereof

Abstract

The application relates to the technical field of materials, and discloses a self-repairing halogen-free flame-retardant polyurethane material for robot cables and a preparation method thereof. The polyurethane material is prepared by mixing and extruding a polyurethane matrix, carbon black, a filler and the like, wherein the polyurethane matrix is prepared by polymerizing a polycarbonate dihydric alcohol as a soft segment, a diisocyanate as a hard segment, a chain extender and a crosslinking agent under the action of a catalyst, wherein the crosslinking agent is a macromolecular substance containing a disulfide bond-cyclophosphamide block alternating structure, which can improve the crosslinking density of the polyurethane molecular chain, make the polyurethane material structure have better compactness, and further improve the mechanical strength of the polyurethane material. The existence of the disulfide bond can endow the polyurethane material with good intrinsic self-repairing performance. The cyclophosphamide structure contains a gas source and an acid source, which can greatly improve the flame-retardant performance of the polyurethane material.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of materials, in particular to a self-repairing halogen-free flame-retardant polyurethane material for robot cables and a preparation method thereof. BACKGROUND

[0002] As the core equipment of intelligent manufacturing, robots have strict requirements on cable motion systems. For example, the end effector of an industrial robot moves at a high speed, and the drag chain system needs to withstand millions of reciprocating bends, and at the same time needs to maintain stable performance in a wide temperature range of-40 DEG C to 85 DEG C. The traditional polyvinyl chloride or crosslinked polyethylene cable sheath will produce a large number of microcracks during the movement of the drag chain, and as the movement intensifies, the cracks will gradually expand, thereby causing failure rate, so in recent years, it has been gradually eliminated.

[0003] Polyurethane (PU) has become an ideal substrate for robot cable sheaths due to its unique micro-phase separation structure. The polyether polyol soft segment can provide flexibility from-50 DEG C to 60 DEG C, and the isocyanate hard segment can form physical crosslinking points through hydrogen bonding, so that the material can still maintain good mechanical strength under high temperature conditions. Therefore, in recent years, polyurethane materials have been increasingly widely used in the field of robot cables. However, there are currently two major technical bottlenecks in the use of polyurethane materials for manufacturing robot cables, one is the lack of self-repairing mechanism, which needs to be replaced manually after mechanical damage, and the other is the low flame retardance, pure polyurethane is a flammable material, which has a great safety hazard.

[0004] Based on this, the application provides a polyurethane material with good comprehensive performance, which can be directly used for manufacturing robot cables. SUMMARY

[0005] (I) Technical problems solved

[0006] In view of the deficiencies of the prior art, the application provides a self-repairing halogen-free flame-retardant polyurethane material for robot cables and a preparation method thereof.

[0007] (II) Technical solutions

[0008] A self-repairing halogen-free flame-retardant polyurethane material for robot cables is prepared by using the following raw materials in the amount of parts by weight:

[0009] 75-95 parts of polyurethane base material, 5-10 parts of carbon black, 4-8 parts of filler, 1-2 parts of lubricant, and 0.5-1.5 parts of coupling agent;

[0010] The preparation method of the polyurethane base material comprises the following steps:

[0011] Step one, the polycarbonate diol is treated with dehydration at a temperature of 100-110℃ for 10-20min, then the temperature is adjusted to 40-50℃, the diisocyanate and tin catalyst are added and stirred, then the temperature is adjusted to 70-80℃, and the pre-polymer is formed by polymerization for 2-4h;

[0012] Step two, the chain extender and crosslinking agent are added to the pre-polymer, after the addition, continue to stir for 1-2h, stop heating, cool down and discharge, and the polyurethane base material is obtained;

[0013] The preparation method of the crosslinking agent comprises the following steps:

[0014] Step S1, add ring phosphorus amide, catalyst and 1,4-dioxane to the reaction kettle filled with nitrogen, after the addition, mechanically stir to form a uniform mixture, then add epoxy propanol to the reaction kettle, after the addition, start heating, increase the temperature to 60-70℃, continue to heat and stir for 2-4h, then evaporate the solvent, collect the product, and purify to obtain the intermediate product;

[0015] Step S2, add the intermediate product, dithio glycolic acid and toluene to the polymerization kettle, stir and mix uniformly, then introduce nitrogen and discharge air, then continue to add the phase transfer catalyst to the polymerization kettle, after the addition, start heating, increase the temperature to 70-80℃ at a heating rate of 2-3℃ / min, continue to heat for 3-6h, then evaporate the solvent, and purify the product to obtain the crosslinking agent;

[0016] The catalyst is sodium hydride; the molar ratio of the catalyst to the ring phosphorus amide is 1.05-1.1:1.

[0017] As a further scheme of the application, the filler is any one of talc, calcium carbonate or titanium white; the lubricant is polyethylene wax; and the coupling agent is 3-aminopropyl trimethoxysilane or 3-aminopropyl triethoxysilane.

[0018] As a further scheme of the application, the mass ratio of the polycarbonate diol, diisocyanate, tin catalyst, chain extender and crosslinking agent is 35-45:15-30:0.3-0.5:1-2:1-3.

[0019] As a further scheme of the application, the diisocyanate is any one of diphenyl methane diisocyanate, toluene diisocyanate or isophorone diisocyanate; the tin catalyst is any one of dibutyl tin dilaurate, stannous octoate, methyl mercaptan tin or octyl mercaptan tin; and the chain extender is ethylene glycol or ethylenediamine.

[0020] As a further scheme of the application, the molar ratio of the ring phosphorus amide to epoxy propanol is 1:2.

[0021] As a further scheme of the present application, the molar ratio of the intermediate product and dithioglycolic acid is 1:1-1.2.

[0022] As a further scheme of the present application, the phase transfer catalyst is any one of tetrabutylammonium hydrogen sulfate, tetramethylammonium chloride, tetramethylammonium bromide, tetrabutylammonium bromide or triethylamine.

[0023] Specifically, first, the halogen substituent in the structure of the cyclophosphamide can be substituted with the active hydroxyl substituent in the structure of the epoxypropanol under the action of the catalyst, and by controlling the dosage ratio of the two, a cyclophosphamide derivative containing two equivalents of epoxy substituents, i.e. the intermediate product, can be prepared. Then, under the action of the phase transfer catalyst, the two equivalents of epoxy substituents in its structure can undergo successive ring-opening esterification with the carboxyl substituent in the structure of dithioglycolic acid to prepare a disulfide-cyclophosphamide block alternating macromolecular substance. Since an additional active hydroxyl functional group is generated during the ring-opening esterification reaction, it can function as a crosslinking agent in the chain extension process of polyurethane, i.e. a crosslinking agent.

[0024] A preparation method of a self-repairing halogen-free flame-retardant polyurethane material for robot cables, comprising the following steps:

[0025] First step, weigh the raw materials according to the weight fraction and prepare them;

[0026] Second step, add the raw materials to the open mill, control the temperature to be 70-80 DEG C, stir and mix for 20-30 min, then transfer the formed mixture to a twin-screw extruder for melt extrusion, and then perform traction, cooling and drying.

[0027] (Three) beneficial technical effects

[0028] The present application prepares a disulfide-cyclophosphamide block alternating macromolecular substance as a crosslinking agent to participate in the chain extension and crosslinking of polyurethane. First, the presence of the crosslinking agent can make the prepared polyurethane molecular chain have higher crosslinking density, and the formed polyurethane material has better structure density, which is beneficial to improving the mechanical strength of the polyurethane material. Second, the crosslinking agent structure contains a reversible dynamic disulfide bond with a fast reversible exchange rate, thereby endowing the polyurethane material with good intrinsic self-repairing performance. Finally, the crosslinking agent structure also contains a cyclophosphamide structure, which contains a gas source and an acid source, and can rapidly catalyze the formation of a dense carbon layer on the surface of the material when the material is on fire, while reducing the surrounding oxygen concentration, thereby preventing the combustion from continuing, and greatly improving the flame retardant performance of the polyurethane material. DETAILED DESCRIPTION

[0029] For the purpose of facilitating the understanding of the present application, a more comprehensive description will be given below. The following presents the preferred embodiments of the present application. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided so that the disclosure of the present application will be more thorough and complete.

[0030] Preparation Example

[0031] Preparation of polyurethane base material:

[0032] Step A, 38 g of polycarbonate diol with a number average molecular weight of 2000 is dehydrated at a temperature of 100℃ for 15 min, then the temperature is adjusted to 45℃, 16 g of diphenylmethane diisocyanate and 0.4 g of dibutyltin dilaurate are added and stirred, then the temperature is adjusted to 75℃, and the polymerization is carried out for 3 h to form a prepolymer;

[0033] Step B, 0.5 g of cyclophosphamide, 0.05 g of sodium hydride and 30 mL of 1,4-dioxane are added to a nitrogen-filled reaction kettle, and mechanical stirring is carried out until a uniform mixture is formed, then 0.28 g of epoxypropanol is added to the reaction kettle, after addition, heating is started, the temperature is raised to 65℃, and after stirring at this temperature for 3 h, the solvent is evaporated, the product is collected, and after purification treatment, an intermediate product is obtained;

[0034] Step C, 0.8 g of the intermediate product, 0.45 g of dithio glycolic acid and 50 mL of toluene are added to the polymerization kettle, and after stirring and mixing uniformly, nitrogen is introduced to remove air, then 0.01 g of tetrabutylammonium bromide is added to the polymerization kettle, after addition, heating is started, the temperature is raised to 80℃ at a rate of 2℃ / min, and after maintaining the temperature for 4 h, the solvent is evaporated, and after purification treatment, a crosslinking agent is obtained;

[0035] Step D, 1.5 g of ethylene glycol and 2.5 g of the crosslinking agent are added to the prepolymer, and after stirring for 2 h, the heating is stopped and the temperature is lowered to obtain the polyurethane base material.

[0036] Example 1

[0037] A self-repairing halogen-free flame-retardant polyurethane material for robot cables is prepared by using the following raw materials in the proportions by weight:

[0038] 75 parts of polyurethane base material, 5 parts of carbon black, 4 parts of filler talc, 1 part of lubricant polyethylene wax, 0.5 part of coupling agent 3-aminopropyltrimethoxysilane;

[0039] The preparation method of the polyurethane material comprises the following steps:

[0040] Step 1, weigh the raw materials according to the proportions by weight;

[0041] Second step, each raw material is added to the open mill, the temperature is controlled at 70℃, stirring and mixing for 30min, then the formed mixture is transferred to the twin-screw extruder for melt extrusion, after traction, cooling and drying, it is ready.

[0042] The preparation method of the polyurethane base material is shown in the preparation example, and the following are the same.

[0043] Example 2

[0044] A self-repairing halogen-free flame-retardant polyurethane material for robot cables is made from the following raw materials measured by weight fraction:

[0045] Polyurethane base material 90 parts, carbon black 6 parts, filler calcium carbonate 6 parts, lubricant polyethylene wax 1.5 parts, coupling agent 3-aminopropyl triethoxysilane 1 part;

[0046] The preparation method of the polyurethane material includes the following steps:

[0047] First step, each raw material is weighed according to the weight fraction and prepared;

[0048] Second step, each raw material is added to the open mill, the temperature is controlled at 72℃, stirring and mixing for 30min, then the formed mixture is transferred to the twin-screw extruder for melt extrusion, after traction, cooling and drying, it is ready.

[0049] Example 3

[0050] A self-repairing halogen-free flame-retardant polyurethane material for robot cables is made from the following raw materials measured by weight fraction:

[0051] Polyurethane base material 95 parts, carbon black 10 parts, filler calcium carbonate 8 parts, lubricant polyethylene wax 2 parts, coupling agent 3-aminopropyl triethoxysilane 1.5 parts;

[0052] The preparation method of the polyurethane material includes the following steps:

[0053] First step, each raw material is weighed according to the weight fraction and prepared;

[0054] Second step, each raw material is added to the open mill, the temperature is controlled at 80℃, stirring and mixing for 20min, then the formed mixture is transferred to the twin-screw extruder for melt extrusion, after traction, cooling and drying, it is ready.

[0055] Comparative Example 1

[0056] A self-repairing halogen-free flame-retardant polyurethane material for robot cables is made from the following raw materials measured by weight fraction:

[0057] Polyurethane base material 90 parts, carbon black 6 parts, filler calcium carbonate 6 parts, lubricant polyethylene wax 1.5 parts, coupling agent 3-aminopropyl triethoxysilane 1 part;

[0058] The preparation method of the polyurethane material comprises the following steps:

[0059] Firstly, each raw material is weighed and prepared;

[0060] Secondly, each raw material is added to an open mill, the temperature is controlled at 72°C, and stirring and mixing are performed for 30 min, then the formed mixture is transferred to a twin-screw extruder for melt extrusion, and after traction, cooling and drying, it is obtained.

[0061] The difference between the preparation method of the polyurethane base material and the preparation example is that no crosslinking agent is added, and the rest are the same.

[0062] Test Example

[0063] According to the standard GB / T 1040.2-2022, the tensile rate is controlled at 50 mm / min, and the mechanical property test is performed;

[0064] According to the standard GB / T 2406.2-2009, the flame retardant performance test is performed;

[0065] The polyurethane material in the examples and comparative examples is made into a sample to be tested with a specification of 10 cm x 10 cm x 5 mm, then a scratch with a depth of 1 mm is drawn on the surface, then it is placed in an oven at 60°C, the time consumed for the scratch to disappear is recorded, and the self-repairing performance of the polyurethane material is evaluated, and the test results are recorded in the following table:

[0066] Table 1-Test Results

[0067]

[0068] According to the analysis of the test results, the polyurethane material prepared by adding the crosslinking agent has excellent mechanical properties, flame retardant performance and self-repairing effect. After removing the crosslinking agent, the structure of the polyurethane material is compact, and the molecular chain does not contain cyclic phosphoramide and dynamic disulfide bond, which leads to a significant decline in the performance of the material.

[0069] The principles and implementations of the present application are described herein with specific examples, and the above description of the embodiments is only used to help understand the method of the present application and its core idea, including the best mode, and also enable any person skilled in the art to practice the present application, including manufacturing and using any device or system, and implementing any combined method. It should be noted that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application. The scope of patent protection of the present application is defined by the claims, and can include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements similar to the textual expression of the claims, or if they include equivalent structural elements that are not substantially different from the textual expression of the claims, then these other embodiments should also be included within the scope of the claims.

[0070] According to the ideal embodiments of the present application, based on the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A self-repairing halogen-free flame-retardant polyurethane material for robot cables, characterized by, The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps: The polyurethane base material is prepared by the following steps:

2. A self-repairing halogen-free flame-retardant polyurethane material for robot cables according to claim 1, characterized in that, The polyurethane base material is prepared by the following steps:

3. A self-repairing halogen-free flame-retardant polyurethane material for robot cables according to claim 1, characterized in that, The polyurethane base material is prepared by the following steps:

4. A self-repairing halogen-free flame-retardant polyurethane material for robot cables according to claim 1, characterized in that, The polyurethane base material is prepared by the following steps:

5. A self-repairing halogen-free flame retardant polyurethane material for robot cables according to claim 1, characterized in that, The polyurethane base material is prepared by the following steps:

6. 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