A low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cable and a preparation method thereof

Abstract

The application discloses a low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cables and a preparation method thereof, and relates to the technical field of high polymer materials. The hydroxyl borate is directly grafted onto a resin matrix used in the sheath material in the form of a chemical reaction, and surface modification is performed on aluminum hydroxide powder and magnesium hydroxide powder, so that the compatibility with the resin matrix is improved, and the resin matrix can further react, the mechanical properties of the sheath material are prevented from being reduced, and a synergistic flame-retardant effect is produced with the hydroxyl borate, the flame-retardant efficiency, the service life and the flame-retardant stability of the prepared sheath material are significantly improved. Moreover, the prepared sheath material does not use halogen-containing materials, and is very environment-friendly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cable and a preparation method thereof. BACKGROUND

[0002] In today's era of information and energy integration development, photoelectric composite cables have been widely used in smart grids, 5G communications, industrial control, rail transportation and other fields due to their characteristics of simultaneously transmitting optical signals and electrical energy. With the increasing requirements of society for fire safety and environmental protection, more stringent standards are required for the performance of sheath materials for photoelectric composite cables. Especially in crowded and complex equipment scenarios, the sheath material not only needs to have excellent flame retardant properties to prevent the spread of fire, but also needs to meet the environmental requirements of low smoke and halogen-free to reduce the release of toxic smoke during combustion, and to gain more time for personnel evacuation and equipment protection.

[0003] At present, the low-smoke halogen-free flame-retardant sheath materials commonly seen in the market mostly use inorganic flame retardants. However, these traditional flame retardants have some defects that are difficult to overcome. On the one hand, in order to achieve a certain flame retardant level, a large amount of addition is often required, which is difficult to disperse and also leads to a decrease in the mechanical properties of the sheath material, such as a decrease in tensile strength, elongation at break and other indicators. Moreover, due to the poor dispersibility of these traditional flame retardants, they are prone to migration, which also affects the service life and reliability of the cable. On the other hand, the traditional flame-retardant system has deficiencies in flame-retardant efficiency and high smoke concentration during combustion, which does not meet the modern fire safety requirements for low smoke.

[0004] In view of the above problems, although there are some improvement schemes in the prior art, the effect is still not ideal. For example, the Chinese patent application with publication number CN112662042A discloses a B1-grade low-smoke halogen-free cable sheath material and a preparation method thereof, the raw materials of which include linear low-density polyethylene resin, ethylene-octene copolymer, compatibilizer, flame retardant, smoke suppression carbonization agent and processing aid. The content of the flame retardant is as high as 60-70%, which reduces the mechanical properties such as tensile strength of the prepared sheath material under the condition of poor dispersibility. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a B1-grade low-smoke halogen-free flame-retardant sheath material for photoelectric composite cable and a preparation method thereof. By grafting the hydroxyl borate directly onto the resin matrix used in the sheath material in the form of chemical reaction, and surface modifying the aluminum hydroxide powder and magnesium hydroxide powder, the compatibility with the resin matrix is improved, and further reaction with the resin matrix is also possible, avoiding the decrease in the mechanical properties of the sheath material, and producing a synergistic flame-retardant effect with the hydroxyl borate, significantly improving the flame-retardant efficiency, service life and flame-retardant stability of the prepared sheath material.

[0006] To achieve the above object, the application adopts the following technical scheme:

[0007] In a first aspect, the application provides a low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cable, which comprises a base resin, a flame-retardant component and a functional additive; the base resin comprises ethylene-vinyl acetate copolymer, polyethylene resin and maleic anhydride grafted ethylene-octene copolymer; the flame-retardant component comprises a hydroxyl-containing borate ester; the hydroxyl-containing borate ester comprises any one of diethanolamine borate monoester and 4-(hydroxyethyl)phenyl boronic acid pinacol ester.

[0008] In a second aspect, the application provides a preparation method of the low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cable, which comprises the following steps:

[0009] The weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, hydroxyl-containing borate ester and catalyst are put into a banbury mixer and mixed at 120-150℃ for 10-15min;

[0010] The weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder are added into the banbury mixer in 3-5 batches, with an interval of 2-3min between each batch;

[0011] The char-forming agent and antioxidant are added in sequence, and the mixing is continued for 5-10min, then the lubricant is added and mixed for 2-5min before discharging and cooling to obtain a mixture to be extruded;

[0012] The mixture to be extruded is put into a twin-screw extruder, and the temperature and screw speed of each section of the twin-screw extruder are controlled;

[0013] After the extruded material is cooled to room temperature, it is cut into particles, thereby obtaining the low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cable.

[0014] Beneficial technical effects:

[0015] In the low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cable prepared by the application, the hydroxyl-containing borate ester reacts with the anhydride groups in the maleic anhydride grafted ethylene-octene copolymer in the base resin through the hydroxyl groups in the molecular structure, producing ester bonds and thereby grafting to the resin molecular chain to form a crosslinked network structure, which enhances the mechanical properties and makes the hydroxyl-containing borate ester stably exist in the prepared sheath material and not easy to migrate, thereby more efficiently playing a flame-retardant role.

[0016] In addition, the amino groups on the surface of the modified aluminum hydroxide powder and the modified magnesium hydroxide powder react with the anhydride groups of the maleic anhydride grafted ethylene-octene copolymer in the high-temperature mixing process to form amide bonds, and also form hydrogen bonds with the ethylene-vinyl acetate copolymer, so that the modified aluminum hydroxide powder and the modified magnesium hydroxide powder form strong interfacial bonding with the matrix resin. This not only improves the dispersibility of the inorganic filler and reduces the agglomeration of the inorganic filler, but also avoids the mechanical property degradation caused by the dispersibility problem.

[0017] Moreover, when there is a fire, the modified aluminum hydroxide powder and the modified magnesium hydroxide powder release a large amount of crystal water during combustion, absorb the heat of combustion, and dilute the concentration of flammable gases. In addition, the hydroxyl borate decomposes to produce boron-containing oxides and water vapor during combustion; the boron-containing oxides cover the surface of the burning material, preventing the diffusion of oxygen to the material and also preventing the escape of flammable gases. In addition, the hydroxyl borate also produces boron-containing radicals during combustion, which capture high-energy radicals produced during the combustion process, thereby interrupting the chain reaction of combustion. The flame-retardant effect of the modified aluminum hydroxide powder, the modified magnesium hydroxide powder, and the hydroxyl borate is synergistic, which can significantly improve the flame-retardant performance of the sheath material prepared. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a physical diagram of the low-smoke halogen-free flame-retardant sheath material for B1-grade optical-electrical composite cables according to the present application;

[0019] Figure 2 is a flowchart schematic diagram of the preparation method of the low-smoke halogen-free flame-retardant sheath material for B1-grade optical-electrical composite cables according to the present application;

[0020] Figure 3 is a schematic diagram of the chemical reaction principle of the hydroxyl borate, the modified aluminum hydroxide, and the modified magnesium hydroxide with the anhydride groups. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below in conjunction with the embodiments. However, this should not be understood as limiting the scope of the present application to the following examples. Without departing from the method idea of the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present application.

[0022] In the present application, the terms used in the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application.

[0023] In the present application, the singular forms "is", "or", "a", "any", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise.

[0024] In addition, if the terms "first", "second" appear, they are only used for the purpose of description and cannot be understood as indicating or implying relative importance.

[0025] In a first aspect, the application provides a low-smoke halogen-free flame-retardant sheath material for B1-level optical fiber composite cable, which is shown in the figure. Figure 1 The low-smoke halogen-free flame-retardant sheath material for B1-level optical fiber composite cable comprises a base resin, a flame-retardant component, and a functional additive; the base resin comprises ethylene-vinyl acetate copolymer, polyethylene resin, and maleic anhydride grafted ethylene-octene copolymer; the flame-retardant component comprises a hydroxyl-containing borate; the hydroxyl-containing borate comprises any one of diethanolamine monoborate and 4-(hydroxyethyl)phenyl pinacol borate.

[0026] In a possible implementation, the flame-retardant component further comprises modified aluminum hydroxide powder and modified magnesium hydroxide powder; and the functional additive comprises a char-forming agent, an antioxidant, and a lubricant.

[0027] In a possible implementation, the mass ratio of the ethylene-vinyl acetate copolymer, the polyethylene resin, the maleic anhydride grafted ethylene-octene copolymer, the modified aluminum hydroxide powder, the modified magnesium hydroxide powder, the hydroxyl-containing borate, the catalyst, the char-forming agent, the antioxidant, and the lubricant is (20-30):(10-20):(3-10):(20-30):(20-30):(5-10):(1-3):(3-5):(0.5-1.5):(0.3-0.5).

[0028] In a possible implementation, the modifier used in the modified aluminum hydroxide powder and the modified magnesium hydroxide powder comprises an amino silane coupling agent; and the amino silane coupling agent comprises one or more of 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, and N-aminoethyl-γ-aminopropyl trimethoxysilane.

[0029] In a possible implementation, the catalyst comprises any one of triethylamine, sodium carbonate, and potassium carbonate.

[0030] In a possible implementation, the modification method of the modified aluminum hydroxide powder and the modified magnesium hydroxide powder comprises the following steps:

[0031] The aluminum hydroxide powder or the magnesium hydroxide powder is put into a high-speed mixer, and the amino silane coupling agent is added in the form of spraying to the dry aluminum hydroxide powder or the magnesium hydroxide powder while stirring;

[0032] After 5-10 min of continuous stirring, the material is discharged, and the obtained material is stored in a vacuum and sealed for 16-24 h to obtain the modified aluminum hydroxide powder or the modified magnesium hydroxide powder.

[0033] In a possible implementation, the particle size of the aluminum hydroxide powder or the magnesium hydroxide powder is 1-20 μm.

[0034] In a possible implementation, the addition amount of the amino silane coupling agent is 1-5% of the mass of the aluminum hydroxide powder or the magnesium hydroxide powder.

[0035] In a second aspect, the application provides a preparation method of a low-smoke halogen-free flame-retardant sheath material for B1-grade photoelectric composite cables, as shown in the following formula (I): Figure 2 The preparation method comprises the following steps:

[0036] The weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, hydroxyl borate and catalyst are put into a banbury mixer, and mixed at 120-150 ℃ for 10-15 min;

[0037] The weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder are added into the banbury mixer in 3-5 batches, and each batch is separated by 2-3 min;

[0038] The char-forming agent and antioxidant are sequentially added, and the mixing is continued for 5-10 min, then the lubricant is added and mixed for 2-5 min, and then the material is discharged and cooled to obtain a to-be-extruded mixture;

[0039] The to-be-extruded mixture is put into a twin-screw extruder, and the temperature and screw speed of each section of the twin-screw extruder are controlled;

[0040] After the extruded material is cooled to room temperature, it is cut into particles, and the B1-grade low-smoke halogen-free flame-retardant sheath material for photoelectric composite cables is prepared.

[0041] In the preparation process of the B1-grade low-smoke halogen-free flame-retardant sheath material for photoelectric composite cables, the principle of the chemical reaction between the hydroxyl borate, the modified aluminum hydroxide and the modified magnesium hydroxide and the anhydride group is as shown in the following formula (II): Figure 3

[0042] In a possible implementation, the temperature of each section of the twin-screw extruder comprises: 150-160 ℃ for the feeding section, 160-180 ℃ for the melting section, and 180-190 ℃ for the homogenizing section.

[0043] In a possible implementation, the screw speed of the twin-screw extruder is 200-300 r / min.

[0044] The following will specifically describe the preparation method of the B1-grade low-smoke halogen-free flame-retardant sheath material for photoelectric composite cables provided by the application in combination with different embodiments.

[0045] Example 1

[0046] As​Figure 2 As shown, a low-smoke, halogen-free flame-retardant sheath material for B1-grade optical-electric composite cables is prepared by the following steps:

[0047] 1. Weigh out the ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride-grafted ethylene-octene copolymer, diethanolamine borate monoester and catalyst and put them into a mixer and mix them at 120°C for 15 minutes.

[0048] 2. Add the weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder into the internal mixer in 5 batches, with an interval of 2 minutes between each batch;

[0049] 3. Add the charring agent and antioxidant in sequence, continue mixing for 5 minutes, then add the lubricant and mix for 5 minutes before discharging and cooling to obtain the mixture to be extruded;

[0050] In steps 1 to 3 above, the mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride-grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, diethanolamine borate monoester, catalyst, charring agent, antioxidant, and lubricant is 20:10:3:29:20:10:1:5:1.5:0.5;

[0051] 4. Feed the mixture to be extruded into the twin-screw extruder, and control the temperature of each section of the twin-screw extruder (feed section 150℃, melting section 160℃, homogenization section 180℃) and the screw speed 200r / min;

[0052] 5. After the extruded material is cooled to room temperature, it is pelletized to obtain the B1 grade low-smoke halogen-free flame-retardant sheath material for optoelectronic composite cables.

[0053] Example 2

[0054] like Figure 2 As shown, a low-smoke, halogen-free flame-retardant sheath material for B1-grade optical-electric composite cables is prepared by the following steps:

[0055] 1. Weigh out the ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride-grafted ethylene-octene copolymer, 4-(hydroxyethyl)phenylboronic acid pinacol ester and catalyst and put them into a mixer and mix them at 130°C for 12 min.

[0056] 2. Add the weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder into the internal mixer in 4 batches, with an interval of 2.5 minutes between each batch;

[0057] 3. Add the charring agent and antioxidant in sequence, continue mixing for 8 minutes, then add the lubricant and mix for 3 minutes before discharging and cooling to obtain the mixture to be extruded;

[0058] The mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, 4-(hydroxyethyl) phenyl boronic pinacol ester, catalyst, char forming agent, antioxidant and lubricant in steps 1-3 above is 25:15:6.6:20:20:6:2:4:1:0.4;

[0059] 4. The extrusion mixture is put into a double screw extruder, and the temperature of each section of the double screw extruder (feed section 155℃, melting section 170℃, homogenization section 185℃) and the screw rotation speed 250r / min are controlled;

[0060] 5. After the extruded material is cooled to room temperature, it is cut into particles, thereby obtaining the B1 grade low smoke halogen-free flame retardant sheath material for photoelectric composite cable.

[0061] Example 3

[0062] As shown in the Figure 2 , a B1 grade low smoke halogen-free flame retardant sheath material for photoelectric composite cable, the preparation method comprises the following steps:

[0063] 1. The weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, 4-(hydroxyethyl) phenyl boronic pinacol ester and catalyst are put into an internal mixer and mixed at 150℃ for 10 minutes;

[0064] 2. The weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder are added into the internal mixer in three batches, with an interval of 3 minutes between each batch;

[0065] 3. The char forming agent and antioxidant are added in turn, and the mixing is continued for 10 minutes, then the lubricant is added and mixed for 2 minutes, and then the material is discharged and cooled to obtain the extrusion mixture;

[0066] The mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, 4-(hydroxyethyl) phenyl boronic pinacol ester, catalyst, char forming agent, antioxidant and lubricant in steps 1-3 above is 20:15:10:20:22:5:3:3.5:1:0.5;

[0067] 4. The extrusion mixture is put into a double screw extruder, and the temperature of each section of the double screw extruder (feed section 160℃, melting section 180℃, homogenization section 190℃) and the screw rotation speed 300r / min are controlled;

[0068] 5. After the extruded material is cooled to room temperature, it is cut into particles, thereby obtaining the B1 grade low smoke halogen-free flame retardant sheath material for photoelectric composite cable.

[0069] Example 4

[0070] As Figure 2 shown in the figure, a B1 grade low smoke halogen-free flame retardant sheath material for photoelectric composite cable, the preparation method comprises the following steps:

[0071] 1, the weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, diethanolamine borate monoester and catalyst into the internal mixer, mixing at 140℃ for 13min;

[0072] 2, the weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder are added into the internal mixer in 5 batches, each batch interval 2min;

[0073] 3, successively add carbonization agent and antioxidant, continue to mix for 6min, then add lubricant and mix for 4min, then discharge and cool, get the extrusion mixture;

[0074] In the above steps 1-3, the mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, diethanolamine borate monoester, catalyst, carbonization agent, antioxidant and lubricant is 22:13:7:23:23:6:2:3:0.6:0.4;

[0075] 4, the extrusion mixture is put into the double screw extruder, the temperature of each section of the double screw extruder is controlled (the feeding section is 155℃, the melting section is 165℃, the homogenization section is 180℃) and the screw speed is 300r / min;

[0076] 5, the extruded material is cooled to room temperature and then granulated, thereby obtaining the B1 grade low smoke halogen-free flame retardant sheath material for photoelectric composite cable.

[0077] Example 5

[0078] As Figure 2 shown in the figure, a B1 grade low smoke halogen-free flame retardant sheath material for photoelectric composite cable, the preparation method comprises the following steps:

[0079] 1, the weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, 4-(hydroxyethyl) phenyl boronic acid pinacol ester and catalyst into the internal mixer, mixing at 125℃ for 14min;

[0080] 2, the weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder are added into the internal mixer in 4 batches, each batch interval 3min;

[0081] 3, successively add carbonization agent and antioxidant, continue to mix for 7min, then add lubricant and mix for 3min, then discharge and cool, get the extrusion mixture;

[0082] In the above steps 1-3, the mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, 4-(hydroxyethyl) phenyl boronic acid pinacol ester, catalyst, char-forming agent, antioxidant and lubricant is 23:14:8:20:24:5:1:4:0.5:0.5;

[0083] 4. The extrusion mixture was put into the twin-screw extruder, and the temperature of each section of the twin-screw extruder (feed section 160°C, melting section 175°C, homogenization section 190°C) and the screw speed 280 r / min were controlled;

[0084] 5. After the extrusion, the material was cooled to room temperature and then pelletized, thereby obtaining the low-smoke halogen-free flame-retardant sheath material for B1 grade photoelectric composite cable.

[0085] Example 6

[0086] As shown in the following, a low-smoke halogen-free flame-retardant sheath material for B1 grade photoelectric composite cable was prepared by the following steps: Figure 2

[0087] 1. The weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, diethanolamine borate monoester and catalyst were put into the internal mixer, and mixed at 135°C for 11 min;

[0088] 2. The weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder were added into the internal mixer in three batches, with an interval of 3 min between each batch;

[0089] 3. The char-forming agent and antioxidant were added in turn, and the mixing was continued for 9 min, then the lubricant was added and mixed for 5 min, and then the material was discharged and cooled, thereby obtaining the extrusion mixture;

[0090] In the above steps 1-3, the mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, diethanolamine borate monoester, catalyst, char-forming agent, antioxidant and lubricant is 22:15:9:22:20:5.5:2:3:1.1:0.4;

[0091] 4. The extrusion mixture was put into the twin-screw extruder, and the temperature of each section of the twin-screw extruder (feed section 155°C, melting section 170°C, homogenization section 185°C) and the screw speed 240 r / min were controlled;

[0092] 5. After the extrusion, the material was cooled to room temperature and then pelletized, thereby obtaining the low-smoke halogen-free flame-retardant sheath material for B1 grade photoelectric composite cable.

[0093] Comparative Example 1 ​

[0094] A low-smoke halogen-free flame-retardant sheath material for an optical-electric composite cable, and a preparation method thereof, the preparation method comprising the following steps:

[0095] 1. Put weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, and catalyst into a banbury mixer, and mix at 120℃ for 15 minutes;

[0096] 2. Add weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder into the banbury mixer in five batches, with an interval of 2 minutes between each batch;

[0097] 3. Add carbonization agent and antioxidant in sequence, continue to mix for 5 minutes, then add lubricant and mix for 5 minutes, and then discharge and cool to obtain a material to be extruded;

[0098] In the above steps 1-3, the mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, modified aluminum hydroxide powder, modified magnesium hydroxide powder, catalyst, carbonization agent, antioxidant, and lubricant is 30:10:3:29:20:1:5:1.5:0.5;

[0099] 4. Put the material to be extruded into a double-screw extruder, control the temperature of each section of the double-screw extruder (150℃ for the feeding section, 160℃ for the melting section, and 180℃ for the homogenization section), and control the screw rotation speed at 200r / min;

[0100] 5. After extrusion, cool the material to room temperature, and then perform granulation, thereby obtaining the B1-grade low-smoke halogen-free flame-retardant sheath material for an optical-electric composite cable.

[0101] Comparative Example 2

[0102] A low-smoke halogen-free flame-retardant sheath material for an optical-electric composite cable, and a preparation method thereof, the preparation method comprising the following steps:

[0103] 1. Put weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, 4-(hydroxyethyl)phenylboronic pinacol ester, and catalyst into a banbury mixer, and mix at 150℃ for 10 minutes;

[0104] 2. Add weighed aluminum hydroxide powder and magnesium hydroxide powder into the banbury mixer in three batches, with an interval of 3 minutes between each batch;

[0105] 3. Add carbonization agent and antioxidant in sequence, continue to mix for 10 minutes, then add lubricant and mix for 2 minutes, and then discharge and cool to obtain a material to be extruded;

[0106] The mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, aluminum hydroxide powder, magnesium hydroxide powder, 4-(hydroxyethyl)phenyl boronic pinacol ester, catalyst, char-forming agent, antioxidant and lubricant in the above steps 1-3 is 20:15:10:20:22:5:3:3.5:1:0.5;

[0107] 4. The extrusion mixture was put into the twin-screw extruder, and the temperature of each section of the twin-screw extruder (feed section 160℃, melting section 180℃, homogenization section 190℃) and the screw speed 300r / min were controlled;

[0108] 5. After the extrusion, the material was cooled to room temperature and then pelletized, thereby obtaining the B1 grade low-smoke halogen-free flame-retardant sheath material for photoelectric composite cable.

[0109] Comparative Example 3

[0110] A low-smoke halogen-free flame-retardant sheath material for photoelectric composite cable, the preparation method comprising the following steps:

[0111] 1. The weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer and catalyst were put into the internal mixer and mixed at 135℃ for 11min;

[0112] 2. The weighed aluminum hydroxide powder and magnesium hydroxide powder were added into the internal mixer in three batches, with an interval of 3min between each batch;

[0113] 3. The char-forming agent and antioxidant were added in turn, and the mixing was continued for 9min, then the lubricant was added and mixed for 5min before discharging and cooling to obtain the extrusion mixture;

[0114] The mass ratio of ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride grafted ethylene-octene copolymer, aluminum hydroxide powder, magnesium hydroxide powder, catalyst, char-forming agent, antioxidant and lubricant in the above steps 1-3 is 27.5:15:9:22:20:2:3:1.1:0.4;

[0115] 4. The extrusion mixture was put into the twin-screw extruder, and the temperature of each section of the twin-screw extruder (feed section 155℃, melting section 170℃, homogenization section 185℃) and the screw speed 240r / min were controlled;

[0116] 5. After the extrusion, the material was cooled to room temperature and then pelletized, thereby obtaining the B1 grade low-smoke halogen-free flame-retardant sheath material for photoelectric composite cable.

[0117] The photoelectric composite cables prepared using the B1 grade low-smoke halogen-free flame-retardant sheath materials prepared in Examples 1-6 and Comparative Examples 1-3 were tested for performance.

[0118] The tensile strength and elongation at break of the optical-electric composite cable were tested using a universal testing machine, and the results of the above tests embodied the mechanical properties of the low-smoke halogen-free flame-retardant sheath material for the prepared optical-electric composite cable.

[0119] The smoke density transmittance of the optical-electric composite cable during combustion was measured using a smoke density tester, and the limiting oxygen index of the optical-electric composite cable was measured using an oxygen index tester, and the results of the two tests embodied the flame-retardant properties and low-smoke effect of the optical-electric composite cable.

[0120] The results of the above tests are shown in Table 1.

[0121] Table 1 Test results of optical-electric composite cables prepared by sheath materials of each example and each comparative example

[0122]

[0123] The optical-electric composite cables prepared by the low-smoke halogen-free flame-retardant sheath materials for the optical-electric composite cables prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to combustion performance tests. The test results are shown in Table 2.

[0124] Table 2 Combustion performance test results of optical-electric composite cables prepared by sheath materials of each example and each comparative example

[0125]

[0126]

[0127] As can be seen from Tables 1 and 2, the performance of the optical-electric composite cables prepared by the low-smoke halogen-free flame-retardant sheath materials for the optical-electric composite cables prepared in Examples 1 to 6 is significantly better than that of the optical-electric composite cables prepared by the low-smoke halogen-free flame-retardant sheath materials for the optical-electric composite cables prepared in Comparative Examples 1 to 3; and the optical-electric composite cables prepared by the low-smoke halogen-free flame-retardant sheath materials for the optical-electric composite cables prepared in Examples 1 to 6 all meet the technical requirements of B1 grade cables after combustion performance tests; and the optical-electric composite cables prepared by the low-smoke halogen-free flame-retardant sheath materials for the optical-electric composite cables prepared in Comparative Examples 1 to 3 all do not meet the technical requirements of B1 grade cables.

[0128] This is because, in the B1 grade low-smoke halogen-free flame-retardant sheath material for the optical-electric composite cable prepared in Examples 1 to 6, the hydroxyl-containing borate reacts with the anhydride groups in the maleic anhydride grafted ethylene-octene copolymer structure in the matrix resin through the hydroxyl groups in the molecular structure to produce ester bonds and graft onto the resin molecular chain, forming a crosslinked network structure, enhancing the mechanical properties, and at the same time, the hydroxyl-containing borate is stably present in the prepared sheath material and is not easy to migrate, thereby more efficiently playing a flame-retardant role.

[0129] In addition, the amino groups on the surface of the modified aluminum hydroxide powder and the modified magnesium hydroxide powder react with the anhydride groups of the maleic anhydride grafted ethylene-octene copolymer in the high-temperature mixing process to form amide bonds, and also form hydrogen bonds with the ethylene-vinyl acetate copolymer, so that the modified aluminum hydroxide powder and the modified magnesium hydroxide powder form strong interfacial bonding with the matrix resin. This not only improves the dispersibility of the inorganic filler and reduces the agglomeration of the inorganic filler, but also avoids the mechanical property decline caused by the dispersibility problem.

[0130] Moreover, when there is a fire, the modified aluminum hydroxide powder and the modified magnesium hydroxide powder release a large amount of crystal water during combustion, absorb the heat of combustion, and dilute the concentration of flammable gas. The hydroxyl borate also decomposes to produce boron-containing oxides and water vapor during combustion; the boron-containing oxides cover the surface of the burning material, preventing the diffusion of oxygen to the material and also preventing the escape of flammable gas. In addition, the hydroxyl borate also produces boron-containing radicals during combustion, which capture high-energy radicals produced during the combustion process, thereby interrupting the chain reaction of combustion. The flame-retardant effect of the modified aluminum hydroxide powder, the modified magnesium hydroxide powder, and the hydroxyl borate is synergistic, which can significantly improve the flame-retardant performance of the prepared sheath material.

[0131] Comparative Example 1 does not use hydroxyl borate, so it cannot react with the anhydride groups in the structure of the maleic anhydride grafted ethylene-octene copolymer to form a crosslinked network structure, and it cannot decompose to produce boron-containing oxides and water vapor during combustion. Therefore, the optical fiber composite cable prepared using the B1-grade low-smoke halogen-free flame-retardant sheath material prepared in Comparative Example 1 has poor mechanical properties.

[0132] Comparative Example 2 uses aluminum hydroxide powder and magnesium hydroxide powder that have not been modified, so they cannot react with the anhydride groups of the maleic anhydride grafted ethylene-octene copolymer to form amide bonds, and they cannot form hydrogen bonds with the ethylene-vinyl acetate copolymer. Therefore, they cannot form strong interfacial bonding with the matrix resin, and it is difficult to avoid the mechanical property decline caused by the dispersibility problem.

[0133] Comparative Example 3 neither uses hydroxyl borate nor modifies the aluminum hydroxide powder and the magnesium hydroxide powder, so the final performance is the worst.

[0134] The above results show and describe the basic principles and main features of the present application, as well as the advantages of the present application.

[0135] Those skilled in the art should understand that the present application is not limited by the above-mentioned embodiments, the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application, and various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the equivalents of the appended claims.

Claims

1. A low-smoke, halogen-free, flame-retardant sheath material for B1-grade optical-electric composite cables, characterized in that, The sheath material comprises a base resin, flame retardant components, and functional additives; the base resin comprises ethylene-vinyl acetate copolymer, polyethylene resin, and maleic anhydride-grafted ethylene-octene copolymer; the flame retardant components comprise hydroxy borate esters, modified aluminum hydroxide powder, and modified magnesium hydroxide powder; the hydroxy borate ester comprises either diethanolamine borate monoester or 4-(hydroxyethyl)phenylboronic acid pinacol ester; the functional additives comprise catalysts, charring agents, antioxidants, and lubricants; the ethylene-vinyl acetate copolymer, polyethylene resin, and maleic anhydride-grafted ethylene-octene copolymer... The mass ratio of the following components is (20~30):(10~20):(3~10):(20~30):(20~30):(5~10):(1~3):(3~5):(0.5~1.5):(0.3~0.5); the catalyst is triethylamine; the modifiers used in the modified aluminum hydroxide powder and modified magnesium hydroxide powder both include aminosilane coupling agents.

2. The low-smoke halogen-free flame-retardant sheath material for B1-grade optical-electric composite cables according to claim 1, characterized in that, The aminosilane coupling agent includes one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and N-aminoethyl-γ-aminopropyltrimethoxysilane.

3. The low-smoke halogen-free flame-retardant sheath material for B1-grade optical-electric composite cables according to claim 1, characterized in that, The modification methods for the modified aluminum hydroxide powder and the modified magnesium hydroxide powder are both... Includes the following steps: Aluminum hydroxide powder or magnesium hydroxide powder is put into a high-speed mixer, and the aminosilane coupling agent is added to the dry aluminum hydroxide powder or magnesium hydroxide powder in the form of spray while stirring. After stirring for 5-10 minutes, discharge the material. The resulting material is then sealed and stored for 16-24 hours after air removal to obtain the modified aluminum hydroxide powder or modified magnesium hydroxide powder.

4. The low-smoke halogen-free flame-retardant sheath material for B1-grade optical-electric composite cables according to claim 3, characterized in that, The particle size of the aluminum hydroxide powder or magnesium hydroxide powder is 1~20μm.

5. The low-smoke halogen-free flame-retardant sheath material for B1-grade optical-electric composite cables according to claim 3, characterized in that, The amount of the aminosilane coupling agent added is 1 to 5% of the mass of the aluminum hydroxide powder or magnesium hydroxide powder.

6. A method for preparing a low-smoke, halogen-free flame-retardant sheath material for B1-grade optoelectronic composite cables according to any one of claims 1 to 5, characterized in that, Includes the following steps: The weighed ethylene-vinyl acetate copolymer, polyethylene resin, maleic anhydride-grafted ethylene-octene copolymer, hydroxy borate ester and catalyst are put into a mixer and mixed at 120~150℃ for 10~15min. The weighed modified aluminum hydroxide powder and modified magnesium hydroxide powder are added to the internal mixer in 3 to 5 batches, with an interval of 2 to 3 minutes between each batch; Add the charring agent and antioxidant in sequence, continue mixing for 5-10 minutes, then add the lubricant and mix for 2-5 minutes before discharging and cooling to obtain the mixture to be extruded; The mixture to be extruded is fed into a twin-screw extruder, and the temperature and screw speed of each section of the twin-screw extruder are controlled. After the extruded material is cooled to room temperature, it is pelletized to obtain the B1 grade low-smoke halogen-free flame-retardant sheath material for optoelectronic composite cables.

7. The method for preparing a low-smoke halogen-free flame-retardant sheath material for B1-grade optoelectronic composite cables according to claim 6, characterized in that, The temperatures of each section of the twin-screw extruder include: 150~160℃ in the feeding section, 160~180℃ in the melting section, and 180~190℃ in the homogenization section.

8. The method for preparing a low-smoke halogen-free flame-retardant sheath material for B1-grade optoelectronic composite cables according to claim 6, characterized in that, The screw speed of the twin-screw extruder is 200~300 r / min.

Images