High flame retardant polyolefin sheath material for automobile electronic wire

Abstract

The present application relates to a high flame-retardant polyolefin sheath material for automobile electronic wire, and belongs to the technical field of sheath material preparation.The sheath material comprises the following raw materials by weight: polyolefin base 40-60 parts, crosslinking promoting resin 20-40 parts, organic flame retardant 18-30 parts, modified inorganic flame retardant 40-70 parts, and photosensitizer 0.1-1 part; the crosslinking promoting resin is made by terminal double bond reaction of terminal hydroxyl dendrimer and methyl acrylate; the terminal hydroxyl dendrimer is made by mixing functional diester monomer and glycerol in a first organic solvent according to a molar ratio of 3:3-4, and then performing thermal reaction under the catalysis of tetrabutyl titanate; the functional diester monomer is made by mixing 2,2,6,6-tetramethylpiperidine amine and methyl acrylate in a second organic solvent according to a molar ratio of 1:2-4, and then performing addition reaction.The present application introduces crosslinking promoting resin and modified inorganic flame retardant, which not only improves the heat resistance of the obtained sheath material, but also endows the obtained sheath material with high flame-retardant performance.

Description

Technical Field

[0001] This invention belongs to the field of sheath material preparation technology, specifically relating to high flame-retardant polyolefin sheath material for automotive electronic wires. Background Technology

[0002] The base resin of existing sheathing materials is generally polyolefin resin. Compared with traditional PVC sheathing materials, polyolefin sheathing materials are halogen-free and environmentally friendly during combustion, representing an important direction for the environmentally friendly development of sheathing materials. However, because polyolefin resins do not contain halogens, they cannot decompose to produce halogen atoms at high temperatures. Consequently, they cannot capture and combine with free radicals in the combustion reaction to halt the oxidation reaction. Therefore, the flame retardant properties of polyolefin resins are far lower than those of PVC. On the other hand, polyolefin resins have poor heat resistance and easily soften and tend to become amorphous at high temperatures, failing to provide the protective function of the sheathing material. This limits the application of polyolefin resin sheathing materials in high-temperature environments (such as electronic wires used in automotive engine management systems).

[0003] Therefore, in the field of polyolefin sheath material preparation technology, there is an urgent need to provide a heat-resistant and flame-retardant polyolefin sheath material for automotive electronic wires. Summary of the Invention

[0004] The purpose of this invention is to provide a high flame-retardant polyolefin sheath material for automotive electronic wires.

[0005] The technical problem this invention aims to solve is that polyolefin sheathing materials have poor heat resistance and cannot be used as sheathing materials in high-temperature environments.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] High flame-retardant polyolefin sheath material for automotive electronic wires comprises the following raw materials in parts by weight: 40-60 parts polyolefin base material, 20-40 parts cross-linking promoting resin, 18-30 parts organic flame retardant, 40-70 parts modified inorganic flame retardant, and 0.1-1 parts photosensitizer.

[0008] The cross-linking promoting resin is made from a hydroxyl-terminated dendritic polymer and methyl acrylate via a terminal double bond reaction.

[0009] The hydroxyl-terminated dendritic polymer is prepared by mixing a functional diester monomer and glycerol in a molar ratio of 3:3-4 in a first organic solvent and then reacting the mixture with tetrabutyl titanate as a catalyst.

[0010] The functional diester monomer is prepared by an addition reaction of 2,2,6,6-tetramethylpiperidineamine and methyl acrylate mixed in a second organic solvent at a molar ratio of 1:2-4.

[0011] In this invention, by introducing a crosslinking-promoting resin (i.e., a dendritic polymer with terminal double bonds formed by the reaction of a hydroxyl-terminated dendritic polymer), the following advantages are achieved: first, the terminal double bonds are utilized to act as a crosslinking agent in the subsequent radiation crosslinking process during molding; second, the branched structure of the dendritic polymer is used to promote the formation of an interpenetrating network in the resulting sheath material during molding; and third, the hindered ammonia structure in the crosslinking accelerator molecular structure (which has the ability to capture free radicals and decompose peroxides, effectively reducing or inhibiting the thermal oxidation and photo-oxidation reaction rate of the resulting sheath material) is utilized to improve the heat resistance of the resulting sheath material and overcome the disadvantage of poor heat resistance of polyolefin resin base materials. Simultaneously with the introduction of the crosslinking accelerator, organic flame retardants and modified inorganic flame retardants are also introduced. It has been found that the crosslinking-promoting resin, the organic flame retardant, and the modified inorganic flame retardant can exert a synergistic flame-retardant effect, endowing the resulting sheath material with high flame-retardant properties.

[0012] Furthermore, the polyolefin base material is selected from either polyethylene resin or polypropylene resin.

[0013] Furthermore, the conditions for the terminal double bond reaction are as follows: the terminal hydroxyl-terminated dendritic polymer and methyl acrylate are reacted in a first organic solvent with tetrabutyl titanate as a catalyst at 140-160°C for 3-12 hours with stirring.

[0014] In the terminal double bond reaction, transesterification occurs between the amino group in the terminal hydroxyl dendritic polymer and the ester group in methyl acrylate at a temperature of 140-160°C.

[0015] Further, the functional diester monomer and glycerol undergo a thermal reaction in a first organic solvent, comprising:

[0016] The functional diester monomer and glycerol are mixed with tetrabutyl titanate in a molar ratio of 3:3-4 in the first organic solvent, heated to the first reaction stage temperature, and stirred for a first predetermined time. Then, the mixture is heated to the second reaction stage temperature and stirred for a second predetermined time. After post-treatment, the hydroxyl-terminated dendritic polymer is obtained.

[0017] In the thermal reaction of functional diester monomer and glycerol in the first organic solvent, the transesterification hyperbranching reaction between the diester group in the functional diester monomer and the dihydroxyl group in the glycerol is utilized, and the molar ratio of functional diester monomer and glycerol is controlled (3:3-4) to form a hydroxyl-terminated dendritic polymer.

[0018] Furthermore, the temperature of the first reaction stage is 90-110℃, and the first predetermined time is 1.5-3h; the temperature of the second reaction stage is 120-150℃, and the second predetermined time is 1.5-3h.

[0019] In the thermal reaction of the functional diester monomer and glycerol in the first organic solvent, the present invention further controls the thermal reaction process by controlling the reaction temperature and reaction time in two stages, thereby improving the number-average molecular weight of the obtained hydroxyl-terminated dendritic polymer and reducing the dispersion of the number-average molecular weight of the obtained hydroxyl-terminated dendritic polymer.

[0020] Furthermore, under the thermal reaction process with the above two-stage reaction temperature and reaction time, the number-average molecular weight of the obtained hydroxyl-terminated dendritic polymer is 20,000-30,000.

[0021] Furthermore, the first organic solvent is one of benzene, toluene, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0022] Furthermore, the addition reaction temperature is 0-40℃, and the reaction time is 4-24h.

[0023] In the addition reaction, the addition reaction between 1 mol of the amino group in 1 mol of 2,2,6,6-tetramethylpiperidineamine and 2 mol of the double bond in 2 mol of methyl acrylate is utilized to form a functional diester monomer.

[0024] Furthermore, the molecular structure of the functional diester monomer is shown below.

[0025]

[0026] Furthermore, the second organic solvent is one of methanol, dichloromethane, benzene, toluene, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0027] Furthermore, the modified inorganic flame retardant is silane coupling agent modified silica.

[0028] Preferably, the silane coupling agent modified silica is a double-bonded silane coupling agent modified silica.

[0029] Furthermore, the organic flame retardant is melamine cyanurate.

[0030] Furthermore, the high flame-retardant polyolefin sheath material for automotive electronic wires also includes 1-5 parts by weight of processing aids, wherein the processing aids are selected from a type of lubricant.

[0031] The beneficial effects of this invention:

[0032] This invention improves the heat resistance of the resulting sheath material and endows it with high flame retardant properties by promoting the introduction of cross-linked resin and modified inorganic flame retardant. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] The silica modified with double-bonded silane coupling agents in the following examples are all KH570 modified silica. The modification method is surface grafting modification, which is well known in the art. The hydrolyzed highly active silanol bonds in the silane coupling agent are hydrolyzed with the hydroxyl bonds on the surface of silica to form grafts, thereby obtaining silica with surface-grafted silane coupling agents. The surface grafting modification process in this invention is a well known process in the art and will not be described in detail here.

[0035] Example 1

[0036] Promoting the preparation of cross-linking resins:

[0037] A1. In an ice-water bath, 0.25 mol of methyl acrylate was added dropwise to a mixture of 0.1 mol of 2,2,6,6-tetramethylpiperidinamine and 60 mL of methanol with stirring. After the addition was complete, the temperature was raised to 20 °C, and the reaction was stirred for 12 h. The solvent was then recovered by rotary evaporation at 60-70 °C, and the excess methyl acrylate was recovered by rotary evaporation at 75-85 °C to obtain a functional diester monomer.

[0038] A2. Mix 0.1 mol of functional diester monomer, 0.3 mol of glycerol, 0.5 g of tetrabutyl titanate and 150 mL of N,N-dimethylacetamide evenly, heat to 100 °C and stir for 1.5 h, then heat to 120 °C and stir continuously for 3 h. Methanol is continuously evaporated during the reaction. After the reaction is completed, evaporate to dryness under reduced pressure to obtain hydroxyl-terminated dendritic polymer.

[0039] A3. The hydroxyl-terminated dendritic polymer obtained in step A2 is mixed with 100 mL of N,N-dimethylacetamide and heated until the hydroxyl-terminated dendritic polymer dissolves. After stirring evenly, excess methyl acrylate (in this example, the amount of methyl acrylate added is equal to the amount of glycerol added) and 0.8 g of tetrabutyl titanate are added. The mixture is heated to 140 °C under reflux and condensation, and stirred for 12 h. Then, excess methyl acrylate is recovered by rotary evaporation at 75-85 °C, and methanol is removed by rotary evaporation at 60-70 °C. After rotary drying, the mixture is washed and dried to obtain the crosslinking-promoting resin.

[0040] Example 2

[0041] Promoting the preparation of cross-linking resins:

[0042] A1. In an ice-water bath, 0.4 mol of methyl acrylate was added dropwise to a mixture of 0.1 mol of 2,2,6,6-tetramethylpiperidinamine and 60 mL of methanol with stirring. After the addition was complete, the temperature was raised to 30 °C, and the reaction was stirred for 12 h. The solvent was then recovered by rotary evaporation at 60-70 °C, and the excess methyl acrylate was recovered by rotary evaporation at 75-85 °C to obtain a functional diester monomer.

[0043] A2. Mix 0.1 mol of functional diester monomer, 0.4 mol of glycerol, 0.6 g of tetrabutyl titanate and 150 mL of N,N-dimethylacetamide evenly, heat to 90 °C and stir for 3 h, then heat to 150 °C and stir continuously for 1.5 h. During the reaction, activated carbon is placed at the tail gas treatment position to absorb the distilled methanol. After the reaction is completed, evaporate to dryness under reduced pressure to obtain the hydroxyl-terminated dendritic polymer.

[0044] A3. The hydroxyl-terminated dendritic polymer obtained in step A2 is mixed with 100 mL of N,N-dimethylacetamide and heated until the hydroxyl-terminated dendritic polymer dissolves. After stirring evenly, excess methyl acrylate (in this example, the amount of methyl acrylate added is equal to the amount of glycerol added) and 1 g of tetrabutyl titanate are added. The mixture is heated to 160 °C under reflux and condensation, and stirred for 3 h. Then, excess methyl acrylate is recovered by rotary evaporation at 75-85 °C, and methanol is removed by rotary evaporation at 60-70 °C. After rotary drying, the mixture is washed and dried to obtain the crosslinking-promoting resin.

[0045] Example 3

[0046] Preparation of high flame-retardant polyolefin sheath material for automotive electronic wires:

[0047] I. Preparation of raw materials including the following parts by weight: 60 parts of low-density polyethylene, 20 parts of the cross-linking promoting resin prepared in Example 1, 18 parts of organic flame retardant (MCA), 70 parts of modified inorganic flame retardant (silica modified with double bond silane coupling agent, silica particle size of 400-500nm), 15 parts of photosensitizer (photoinitiator 819), and 1 part of lubricant (polyethylene wax);

[0048] 2. Add the above-mentioned raw materials by weight into a twin-screw extruder for extrusion and granulation to obtain the sheath material.

[0049] Example 4

[0050] Preparation of high flame-retardant polyolefin sheath material for automotive electronic wires:

[0051] I. Preparation of raw materials including the following parts by weight: 50 parts of low-density polyethylene, 30 parts of the cross-linking promoting resin prepared in Example 2, 24 parts of organic flame retardant (MCA), 60 parts of modified inorganic flame retardant (silica modified with double bond silane coupling agent, with a particle size of 400-500nm), 0.5 parts of photosensitizer (photoinitiator 819), and 2 parts of lubricant (polyethylene wax);

[0052] 2. Add the above-mentioned raw materials by weight into a twin-screw extruder for extrusion and granulation to obtain the sheath material.

[0053] Example 5

[0054] Preparation of high flame-retardant polyolefin sheath material for automotive electronic wires:

[0055] I. Preparation of raw materials including the following parts by weight: 40 parts of low-density polyethylene, 40 parts of the cross-linking promoting resin prepared in Example 1, 30 parts of organic flame retardant (MCA), 45 parts of modified inorganic flame retardant (silica modified with double bond silane coupling agent, with a particle size of 400-500nm), 1 part of photosensitizer (photoinitiator 819), and 5 parts of lubricant (polyethylene wax).

[0056] 2. Add the above-mentioned raw materials by weight into a twin-screw extruder for extrusion and granulation to obtain the sheath material.

[0057] Comparative Example 1

[0058] Preparation of sheath material:

[0059] Compared with Example 3, the cross-linking promoting resin in the raw materials was replaced with an equal amount of the hydroxyl-terminated dendritic polymer prepared in step A2 of Example 3, and the rest were the same.

[0060] Comparative Example 2

[0061] Preparation of sheath material:

[0062] Compared to Example 3, the cross-linking promoting resin in the raw materials was removed, while the rest remained the same.

[0063] Comparative Example 3

[0064] Preparation of sheath material:

[0065] Compared with Example 3, the modified inorganic flame retardant in the raw materials was removed, while the rest remained the same.

[0066] Comparative Example 4

[0067] Preparation of sheath material:

[0068] Compared to Example 3, the organic flame retardant in the raw materials was removed, but the rest were the same.

[0069] Comparative Example 5

[0070] Preparation of sheath material:

[0071] Compared with Example 3, the cross-linking promoting resin, organic flame retardant and modified inorganic flame retardant in the raw materials were removed, while the rest were the same.

[0072] After irradiation molding, the sheath materials obtained in Examples 3-5 and Comparative Examples 1-5 were subjected to physical property tests, and the results are shown in Table 1. UV aging resistance was tested according to GB / T 16422.3 for 168 hours, followed by tensile strength testing and calculation of the rate of decrease in tensile strength. Heat aging resistance was tested according to GB / T 7141; after the heat aging test, tensile strength was tested and the rate of decrease in tensile strength was calculated.

[0073] Table 1

[0074]

[0075] As can be seen from the data in Table 1, the sheathing materials obtained in Examples 3-5 have good heat resistance, heat aging resistance, UV aging resistance and flame retardancy.

[0076] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0077] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A high flame-retardant polyolefin sheath material for automotive electronic wires, characterized in that, The raw materials include the following parts by weight: 40-60 parts of polyolefin base material, 20-40 parts of cross-linking promoting resin, 18-30 parts of organic flame retardant, 40-70 parts of modified inorganic flame retardant, and 0.1-1 parts of photosensitizer; The cross-linking promoting resin is made from a hydroxyl-terminated dendritic polymer and methyl acrylate via a terminal double bond reaction. The hydroxyl-terminated dendritic polymer is prepared by mixing a functional diester monomer and glycerol in a molar ratio of 3:3-4 in a first organic solvent and then reacting the mixture with tetrabutyl titanate as a catalyst. The functional diester monomer is prepared by mixing 2,2,6,6-tetramethylpiperidineamine and methyl acrylate in a second organic solvent at a molar ratio of 1:2-4 and then reacting them by addition reaction. The modified inorganic flame retardant is silane coupling agent-modified silica, and the organic flame retardant is melamine cyanurate.

2. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, The polyolefin base material is selected from either polyethylene resin or polypropylene resin.

3. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, The conditions for the terminal double bond reaction are as follows: the terminal hydroxyl dendritic polymer and methyl acrylate are reacted in a first organic solvent with tetrabutyl titanate as a catalyst at 140-160°C for 3-12 hours.

4. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, The thermal reaction of the functional diester monomer and glycerol includes: The functional diester monomer and glycerol are mixed with tetrabutyl titanate in a molar ratio of 3:3-4 in the first organic solvent, heated to the first reaction stage temperature, and stirred for a first predetermined time. Then, the mixture is heated to the second reaction stage temperature and stirred for a second predetermined time. After post-treatment, the hydroxyl-terminated dendritic polymer is obtained.

5. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 4, characterized in that, The temperature of the first reaction stage is 90-110℃, and the first predetermined time is 1.5-3h. The temperature of the second reaction stage is 120-150℃, and the second predetermined time is 1.5-3h.

6. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, The first organic solvent is one of benzene, toluene, N,N-dimethylformamide, and N,N-dimethylacetamide.

7. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, The addition reaction temperature is 0-40℃, and the reaction time is 4-24h.

8. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, The second organic solvent is one of methanol, dichloromethane, benzene, toluene, N,N-dimethylformamide, and N,N-dimethylacetamide.

9. The high flame-retardant polyolefin sheath material for automotive electronic wires according to claim 1, characterized in that, It also includes 1-5 parts by weight of processing aids, which are selected from a type of lubricant.

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