Environment-friendly PP filling strip for submarine cable and preparation method of environment-friendly PP filling strip

Abstract

The invention discloses an environment-friendly PP filling strip for a submarine cable and a preparation method of the environment-friendly PP filling strip, belongs to the technical field of polypropylene resin processing, and aims to solve the technical problem that the chemical stability and the mechanical strength of a PP filling strip for a submarine cable in the prior art need to be further improved. The modified polypropylene resin comprises the following components in parts by weight: 100-120 parts of modified polypropylene resin, 1-5 parts of an antioxidant, 5-10 parts of a lubricant and 5-10 parts of a seawater protective agent, cross-linked polypropylene resin is obtained through polymerization, and a modified filler is prepared and is subjected to blending heat treatment with the cross-linked polypropylene resin to obtain the modified polypropylene resin. Melting and extruding with auxiliary materials to obtain a PP filling strip precursor, and foaming through carbon dioxide supercritical fluid to obtain the temperature-resistant, high-chemical-stability, high-whiteness, wear-resistant and high-toughness PP filling strip for the submarine cable.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene resin processing, and in particular to an environmentally friendly PP filling strip for submarine cables and a preparation method thereof. Background Art

[0002] Submarine cables usually contain sensitive components such as optical fibers, which require good protection to prevent mechanical damage and environmental erosion. PP filler strips, as a filling material, can effectively isolate the optical fibers and other components inside the cable, reduce the impact of external pressure and extrusion, and protect the structural integrity and performance stability. The filler strips can not only protect the internal components of the cable, but also provide certain mechanical support and compressive resistance when the cable is subjected to external pressure. The structure of the PP filler strip can also disperse the impact of external forces on the cable, reduce single-point pressure, and help extend the service life of the cable.

[0003] In the prior art, PP filling strips are used to replace metal wires and high-performance fibers as filling materials inside submarine cables to reduce costs to a certain extent. However, the polypropylene component structure inside traditional PP filling strips is simple, such as homopolymer polypropylene, which is polymerized from propylene monomers without the addition of other comonomers. Although it has a high degree of crystallinity, its simple molecular chain structure leads to weak mechanical strength and tensile strength, making it difficult to cope with the complex submarine environment. In addition, the chemical stability of the PP filling strips in the prior art is low. After the submarine cable is damaged, the filling strips will come into contact with the marine environment, which is easy to cause pollution to the marine environment. At the same time, the optical performance is also weak, and it cannot serve as a warning after the cable is damaged.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0005] The object of the present invention is to provide an environmentally friendly PP filling strip for submarine cables and a preparation method thereof, so as to solve the technical problem that the chemical stability and mechanical strength of the PP filling strip for submarine cables in the prior art need to be further improved.

[0006] The object of the present invention can be achieved by the following technical scheme: an environmentally friendly PP filling strip for submarine cables, comprising 100-120 parts by weight of a modified polypropylene resin, 1-5 parts by weight of an antioxidant, 5-10 parts by weight of a lubricant, and 5-10 parts by weight of a seawater protective agent;

[0007] The preparation method of the modified polypropylene resin is as follows: 80-100 parts of cross-linked polypropylene resin and 20-30 parts of modified filler are weighed by weight and mixed evenly to obtain a composite polypropylene resin, the composite polypropylene resin is placed in a tubular furnace, nitrogen is introduced for protection, the tubular heating furnace is heated to 300±5°C at a rate of 10°C / min, and after keeping warm for 2-3 hours, it is naturally cooled to room temperature to obtain the modified polypropylene resin.

[0008] Modified polypropylene resin synthesis reaction equation:

[0009]

[0010] The synthetic reaction principle of modified polypropylene resin is: under high temperature conditions, the secondary amine and hydroxyl in the foamed PP filling strip undergo thermal imidization reaction to form modified polypropylene resin.

[0011] Furthermore, the preparation method of the cross-linked polypropylene resin is as follows: 4-6 parts of modified monomer, 3-5 parts of styreneethyltrimethoxysilane, 4-6 parts of 4,4'-bis(2-sulfonylstyrene)-1,1'-biphenyl, 0.3-0.5 parts of azobisisobutyronitrile and 15-20 parts of dimethyl sulfoxide are weighed by weight and added into a reactor, the temperature of the reactor is increased to 50-70°C, the reaction is kept warm for 2-4 hours, and the cross-linked polypropylene resin is obtained by post-treatment.

[0012] The synthesis reaction equation of cross-linked polypropylene resin is:

[0013]

[0014] Where:

[0015] The synthesis reaction principle of cross-linked polypropylene resin is as follows: under the action of azobisisobutyronitrile as a free radical initiator, the modified monomer, styreneethyltrimethoxysilane and 4,4'-bis(2-sulfonylstyrene)-1,1'-biphenyl undergo free radical polymerization to ultimately generate cross-linked polypropylene resin.

[0016] Furthermore, the post-treatment operation is as follows: after the reactor is cooled to room temperature, the reaction liquid is added into a rotary evaporator with a water bath temperature of 80-100° C., and distilled under reduced pressure until no liquid is extracted to obtain a cross-linked polypropylene resin.

[0017] Furthermore, the preparation method of the modified monomer is as follows: 20-30 parts by weight of 4,4'-diaminostilbene-2,2'-disulfonic acid, 5-10 parts of phthalic anhydride, 75-100 parts of N,N-dimethylformamide and 1-3 parts of triethylamine are added to a reaction kettle, stirred at room temperature for 2-4 hours, and post-treated to obtain the modified monomer.

[0018] The synthetic reaction equation of the modified monomer is:

[0019]

[0020] The principle of the modified monomer synthesis reaction is: 4,4'-diaminostilbene-2,2'-disulfonic acid with an amino group undergoes a nucleophilic reaction to attack the carbonyl carbon atom in the phthalic anhydride molecule, wherein the nitrogen atom of the amino group carries a lone pair of electrons, and these electron pairs can form new covalent bonds with the carbonyl carbon atom to form a polyamic acid monomer connected by an aminoacyl group, and finally a modified monomer is prepared.

[0021] Furthermore, the post-treatment operation is as follows: after the reactor is cooled to room temperature, the reaction liquid is added into a rotary evaporator with a water bath temperature of 80-100° C., and distilled under reduced pressure until no liquid is extracted to obtain a modified monomer.

[0022] Furthermore, the preparation method of the modified filler comprises the following steps:

[0023] A1. Weigh 150-180 parts of 95wt% ethanol, 3-5 parts of silane coupling agent KH-560 and 10-20 parts of modified β-nucleating agent by weight, add them into an ultrasonic device, set the frequency to 20-40KHz, and ultrasonicate for 4-6h at room temperature to obtain a dispersion;

[0024] A2, placing the expandable graphite in a pulverizer and crushing it, passing it through a 60-mesh sieve to obtain expandable graphite powder, placing the expandable graphite powder in a tubular furnace, introducing nitrogen protection, raising the temperature of the tubular furnace to 800±5°C at a rate of 10°C / min, and keeping the temperature for 2-3h to obtain expandable graphite powder;

[0025] A3. Weigh 20-30 parts of dispersion and 1-2 parts of expanded graphite powder by weight, place the expanded graphite powder in a reactor and stir, set the stirring rate to 350-400 rpm, add the dispersion into an atomizer and spray it onto the expanded graphite powder at a rate of 1-3 parts / min. After spraying, continue stirring for 10-15 minutes, and post-treat to obtain a modified filler.

[0026] Reaction principle: The dispersion is sprayed onto the surface of expanded graphite powder through atomization, and then vacuum dried to make graphene evenly adsorbed or intercalated on the surface of expanded graphite powder.

[0027] Furthermore, the post-processing operation is: placing the material in the reactor in a drying oven at a temperature of 80° C. and a pressure of −0.06 MPa to dry to a constant weight, thereby obtaining a modified filler.

[0028] Furthermore, the preparation method of the modified β-nucleating agent is as follows: 10-15 parts of modified graphene, 5-8 parts of terephthaloyl chloride, 50-60 parts of N,N-dimethylformamide and 2-3 parts of triethylamine are weighed by weight, stirred at room temperature for 2-4 hours, and post-treated to obtain the modified β-nucleating agent.

[0029] The reaction equation of modified β nucleating agent is:

[0030]

[0031] The reaction equation of the modified β nucleating agent is: the nitrogen atom in the amino group on the surface of the modified graphene carries a lone pair of electrons and has a nucleophilic property. The carbonyl carbon atom in the acyl chloride group in terephthaloyl chloride carries a partial positive charge. Because the oxygen atom has a strong electron-withdrawing ability, the carbonyl carbon atom is partially positively charged. The lone pair of electrons in the amino group can attack this partial positive charge, resulting in a nucleophilic substitution reaction, and finally generating a modified β nucleating agent.

[0032] Furthermore, the post-treatment operation is: after the temperature of the reactor is lowered to room temperature, the filter cake is collected by suction filtration, and the filter cake is placed in a drying oven at a temperature of 80° C. and vacuum dried until the filter cake has a constant weight, thereby obtaining a modified β-nucleating agent.

[0033] Furthermore, the preparation method of modified graphene is as follows: 10-20 parts of activated graphene, 1-2 parts of 3-aminopropylethoxysilane, 40-50 parts of N,N-dimethylformamide and 0.5-0.8 parts of triethylamine are weighed and added into a reactor, the temperature of the reactor is increased to 40-60° C., the reaction is kept warm for 2-4 hours, and the modified graphene is obtained by post-treatment.

[0034] The reaction equation for the synthesis of modified graphene is:

[0035]

[0036] The principle of the modified graphene synthesis reaction is: under weakly alkaline conditions, the ethoxy group of 3-aminopropylethoxysilane will be hydrolyzed to generate silanol groups, which will combine with the hydroxyl groups on the surface of activated graphene to form silicon-oxygen bonds, thereby achieving cross-linking between particles and preparing modified graphene.

[0037] Furthermore, the post-treatment operation is: after the temperature of the reactor is lowered to room temperature, the filter cake is collected by suction filtration, and the filter cake is placed in a drying oven at a temperature of 80° C. and vacuum dried until the filter cake has a constant weight, thereby obtaining modified graphene.

[0038] Furthermore, the preparation method of activated graphene is as follows: a single-layer graphene is placed in a pulverizer and crushed, and passed through a 100-mesh sieve to obtain a single-layer graphene powder, and after the single-layer graphene powder is transferred to a reactor, nitrogen is introduced for protection, and after the temperature of the reactor is raised to 60-80°C, the reactor is heated at 50 cm 3Oxygen was introduced into the reactor at a flow rate of 25 cm / min, and the temperature was kept at 1-2 h. 3 Water vapor is introduced into the reactor at a flow rate of 100 Å / min, the temperature is kept for 1-2 h, and the reactor is naturally cooled to obtain activated graphene.

[0039] The reaction principle for preparing activated graphene: Under high temperature, oxygen oxidizes the graphene surface to form active sites, and water vapor is introduced under high temperature conditions to produce a hydration reaction to prepare activated graphene.

[0040] Furthermore, the antioxidant is one or more of tri-tert-butyl hydroxyphenyl acrylate, tetramethyl dihydroxyphenyl acrylate and tri-tert-butyl hydroxyphenyl acrylate; the seawater protective agent is one or more of polyurethane elastomer, polymer modified oil and silane cross-linked polyethylene ester; the lubricant is one or more of lead stearate, distearate glycerol and polyethylene wax.

[0041] The present invention also provides a method for preparing an environmentally friendly PP filling strip for a submarine cable, comprising the following steps:

[0042] S1. uniformly mixing the modified polypropylene resin, the antioxidant, the lubricant and the seawater protective agent to obtain a mixture;

[0043] S2. Add the mixed material into a twin-screw extruder, wherein the temperatures of the eight temperature sections of the twin-screw extruder from the feed port to the discharge port are 260° C., 265° C., 265° C., 270° C., 270° C., 280° C., and 280° C., respectively, and the main engine speed of the twin-screw extruder is 80-120 rpm, and the pressure is 100-150 bar, and the PP filling strip precursor is obtained by melt extrusion;

[0044] S3. Place the PP filling bar precursor in a high-pressure reactor, place the high-pressure reactor in a salt bath furnace, exhaust the air in the high-pressure reactor with carbon dioxide gas, and then use a booster to introduce 15-18MPa carbon dioxide gas into the high-pressure reactor. The temperature of the salt bath furnace rises to 100-140°C. During the heating process, observe the internal pressure of the high-pressure reactor, use valves on both sides to vent and release the pressure, control the pressure in the reactor to be less than 30MPa, keep the reaction warm for 1-2h, and obtain the PP filling bar after post-treatment.

[0045] The reaction principle for preparing foamed PP filling strips is: using carbon dioxide gas under high temperature conditions to reach a supercritical fluid state, using the supercritical fluid's strong solubility and dispersion capabilities to form a uniform PP / gas homogeneous system, and then quickly releasing the pressure to obtain the PP filling strips.

[0046] Furthermore, the post-processing operation is: after quickly releasing the pressure using a pneumatic valve, the material is quickly taken out and placed in an ice water bath for 15-20 minutes, and then the material is placed in a drying oven at a temperature of 80° C. and vacuum dried until the material has a constant weight, thereby obtaining a PP filling bar.

[0047] The present invention has the following beneficial effects:

[0048] 1. In the process of preparing an environmentally friendly PP filling strip for submarine cables, the present invention firstly obtains a high chemical stability and high temperature resistant monomer by modifying the anti-salt monomer, and then further polymerizes it with fluorescent and siloxane monomers to obtain a high chemical stability and high temperature resistant cross-linked polypropylene, and further prepares a modified filler with a β nucleating agent and strong thermal conductivity. After the modified filler is blended with the cross-linked polypropylene and heated, the internal heat is uniformly promoted to promote its thermal imidization reaction, and further produce a β crystal form, so that the mechanical properties of the prepared modified polypropylene are greatly improved. At the same time, its excellent thermal conductivity significantly improves the efficiency and effect of carbon dioxide supercritical fluid foaming, and its excellent internal void structure can be used as a core and foaming agent for gas release, so that the foaming effect is further improved, and finally a high chemical stability, high temperature resistance, high whiteness, wear resistance and high toughness environmentally friendly PP rope for submarine cable filling is prepared.

[0049] 2. In the process of preparing a modified acrylic resin, phthalic anhydride is first used to modify 4,4'-diaminostilbene-2,2'-disulfonic acid to replace the amino group to obtain a modified monomer having an amide group and a sulfonic acid group. The amide group has a stable structure in seawater relative to the amino group, which reduces the impact of hydrolysis or protonation in seawater on the environment and provides a basis for subsequent reactions. The modified monomer is further polymerized with styrene ethyl trimethoxy silane and a fluorescent brightener 4,4'-bis(2-sulfonic acid styrene)-1,1'-biphenyl to generate cross-linked polypropylene. The siloxane structure in the formed cross-linked polypropylene enhances the cross-linking performance of the remaining inorganic auxiliary materials and further improves its wear resistance. The siloxane structure cooperates with the ring structure inside the fluorescent brightener 4,4'-bis(2-sulfonic acid styrene)-1,1'-biphenyl to jointly enhance its Toughness; further, the fluorescent brightener 4,4'-bis(2-sulfonylphenylvinyl)-1,1'-biphenyl will increase the visual effect of the resin, provide a warning when the cable breaks, facilitate later repairs, and prevent the substances inside the cable from further diffusing into the marine environment and causing pollution to the marine environment. At the same time, the sulfonate group it possesses cooperates with the sulfonate group of the modified monomer to chelate with metal ions such as sodium ions and calcium ions in seawater to form a stable complex without reducing the whiteness of the polypropylene resin, thereby further enhancing the chemical stability of the final product and reducing pollution to the ocean; finally, by mixing it with the modified filler and heating it to produce a thermal amidation reaction, the temperature resistance of the PP rope is further improved, thereby obtaining an environmentally friendly modified polypropylene resin with high temperature resistance, high chemical stability, high whiteness, wear resistance and high toughness.

[0050] 3. In the process of preparing a modified filler, the present invention selects a single-layer graphene as a base material to prepare activated graphene. The single-layer graphene has a large number of edges and defect sites. These sites make it have rich chemical reaction activity. At the same time, the single-layer graphene has a very low light absorption rate of about 2.3%. It also has a high light transmittance, and will not reduce the optical properties of the polypropylene resin in subsequent operations. Further, the single-layer graphene is crushed, sieved, and oxidized by oxygen and hydrated with water vapor to obtain an activated graphene, so that the reaction activity and dispersion of the graphene are further improved; further, the silane coupling agent 3-aminopropylethoxysilane is used to modify the surface and introduce amino groups, which provides a basis for preparing a modified β nucleating agent, and the cross-linking effect of the silane coupling agent further improves its stability; further, terephthaloyl chloride is used to modify the modified graphene The amino groups on the surface react to generate an amide-modified β-nucleating agent, and by preparing a dispersion, atomizing adsorption or intercalating the expanded graphite obtained after crushing, sieving and high-temperature expansion, a composite modified filler with the properties of promoting polypropylene to form β-crystal, thermal conductivity and foaming agent is obtained, which is further mixed with cross-linked polypropylene resin and heated to promote its formation of β-crystal. The molecular chains of the β-crystal polypropylene resin are arranged more orderly and have higher crystallinity, which further improves its impact resistance. The cross-linked polypropylene resin undergoes a thermal nicotinamide reaction to improve its thermal performance and foaming effect by utilizing its excellent thermal conductivity and excellent porosity. Furthermore, after foaming, the density of the PP filling strip is reduced and the mechanical properties are significantly improved. The foamed PP filling strip marked with the filling position information can quickly locate the damaged position, thereby improving the maintenance construction efficiency. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] The single-layer graphene used in the present invention has a transparency greater than 97%, a thickness of 0.345-0.350nm, and a maximum particle size of 10μm; the expansion multiple of the expanded graphite used in the present invention is more than 350 times, and the particle size is greater than 300μm; the gel rate of the silane cross-linked polyethylene ester used in the present invention is 70-75%, the relative density is 0.923-0.929, and the elongation at break is 500-600%.

[0053] Example 1

[0054] This embodiment provides a method for preparing an environmentally friendly PP filling strip for a submarine cable, comprising the following steps:

[0055] S1. Preparation of modified β nucleating agent

[0056] Weigh 24.0 g of single-layer graphene, place the single-layer graphene in a grinder and grind it through a 100-mesh sieve to obtain single-layer graphene powder. After the single-layer graphene powder is transferred to a reactor, nitrogen is introduced for protection. After the temperature of the reactor is raised to 60°C, the reactor is heated at 50 cm 3 Oxygen was introduced into the reactor at a flow rate of 25 cm / min and kept warm for 1 h. 3 Water vapor was introduced into the reactor at a flow rate of / min, and the temperature was kept for 1h. After natural cooling, 23.2g of activated graphite was obtained;

[0057] 20.0 g of activated graphene, 4.0 g of 3-aminopropylethoxysilane, 84.0 g of N,N-dimethylformamide and 1.2 g of triethylamine were weighed and added to a reactor. The temperature of the reactor was raised to 40° C. and the reaction was kept warm for 2 h. After the temperature of the reactor was lowered to room temperature, the filter cake was collected by filtration and placed in a drying oven at 80° C. and vacuum dried until the filter cake had a constant weight, to obtain 21.5 g of modified graphene.

[0058] Weigh 19.5 g of modified graphene, 10.5 g of terephthaloyl chloride, 81.0 g of N,N-dimethylformamide and 3.2 g of triethylamine and stir at room temperature for 2 h. After the temperature of the reactor is lowered to room temperature, the filter cake is collected by filtration and placed in a drying oven at 80°C for vacuum drying until the filter cake has a constant weight to obtain 28.5 g of modified β nucleating agent.

[0059] S2. Preparation of modified filler

[0060] Weigh 264.5 g of 95 wt% ethanol, 6.9 g of silane coupling agent KH-560 and 26.4 g of modified β-nucleating agent, add them to an ultrasonic device, set the frequency to 40 KHz, and ultrasonicate at room temperature for 4 hours to obtain 250.3 g of dispersion;

[0061] Weigh 10.0 g of expandable graphite, place the expandable graphite in a grinder and grind it, pass it through a 60-mesh sieve to obtain expandable graphite powder, place the expandable graphite powder in a tubular furnace, introduce nitrogen protection, raise the temperature of the tubular furnace to 795° C. at a rate of 10° C. / min, and keep it warm for 2 h to obtain 9.8 g of expandable graphite powder;

[0062] Weigh 240.0g of the dispersion and 8.3g of expanded graphite powder, place the expanded graphite powder in a reactor and stir, set the stirring rate to 350rpm, add the dispersion into an atomizer and spray it onto the expanded graphite powder after atomization at a rate of 4.2g / min. After spraying, continue stirring for 10min, and post-process to obtain 32.3g of modified filler.

[0063] S3. Preparation of modified polypropylene resin

[0064] Weigh 40.0 g of 4,4'-diaminostilbene-2,2'-disulfonic acid, 10.0 g of phthalic anhydride, 140.0 g of N,N-dimethylformamide and 4.0 g of triethylamine into a reactor, stir at room temperature for 2 h, and after the reactor is cooled to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 80°C, and distill under reduced pressure until no liquid is produced, to obtain 45.6 g of modified monomer;

[0065] 41.1 g of modified monomer, 32.9 g of styreneethyltrimethoxysilane, 41.1 g of 4,4'-bis(2-sulfonylstyrene)-1,1'-biphenyl, 3.3 g of azobisisobutyronitrile and 147.9 g of dimethyl sulfoxide were weighed and added to a reactor. The temperature of the reactor was raised to 50° C. and the reaction was kept warm for 2 h. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a water bath temperature of 80° C. and distilled under reduced pressure until no liquid was produced to obtain 112.5 g of cross-linked polypropylene resin;

[0066] Weigh 90.0 g of cross-linked polypropylene resin and 24.0 g of modified filler and mix them evenly to obtain a composite polypropylene resin. Place the composite polypropylene resin in a tubular furnace and introduce nitrogen protection. After the tubular heating furnace is raised to 295°C at a rate of 10°C / min, it is kept warm for 2 hours and then naturally cooled to room temperature to obtain 113.5 g of modified polypropylene resin.

[0067] S4. Preparation of PP rope

[0068] Weigh 112.0 g of modified polypropylene resin, 3.6 g of tri-tert-butyl hydroxyphenyl acrylate, 5.4 g of polyethylene wax and 5.4 g of silane cross-linked polyethylene ester and mix them evenly to obtain 126.4 g of a mixture;

[0069] 125.0 g of the mixed material was weighed and added to a twin-screw extruder. The temperatures of the eight temperature sections of the twin-screw extruder from the feed port to the discharge port were 260° C., 265° C., 265° C., 270° C., 270° C., 280° C., and 280° C., respectively. The main engine speed of the twin-screw extruder was 80 rpm, and the pressure was 100 bar. 124.5 g of PP filling strip precursor was obtained by melt extrusion.

[0070] Weigh 120.0g of PP filling bar precursor and place it in a high-pressure reactor, place the high-pressure reactor in a salt bath furnace, use carbon dioxide gas to exhaust the air in the high-pressure reactor, use a booster to pass 15MPa carbon dioxide gas into the high-pressure reactor, and raise the temperature of the salt bath furnace to 100°C. Observe the internal pressure of the high-pressure reactor during heating, use valves on both sides to vent and release the pressure, control the pressure in the reactor to be less than 30MPa, keep the reaction warm for 1h, use a pneumatic valve to quickly release the pressure, quickly take out the material and put it in an ice water bath for 15, then place the material in a drying oven at 80°C and vacuum dry it until the material has a constant weight, to obtain 119.4g of PP filling bars.

[0071] Example 2

[0072] This embodiment provides a method for preparing an environmentally friendly PP filling strip for a submarine cable, comprising the following steps:

[0073] S1. Preparation of modified β nucleating agent

[0074] Weigh 25.0 g of single-layer graphene, place the single-layer graphene in a grinder, and grind it through a 100-mesh sieve to obtain single-layer graphene powder. After the single-layer graphene powder is transferred to a reactor, nitrogen is introduced for protection. After the temperature of the reactor is raised to 80°C, the reactor is heated at 50 cm 3 Oxygen was introduced into the reactor at a flow rate of 25 cm / min, and the temperature was kept at room temperature for 2 h. 3 Water vapor was introduced into the reactor at a flow rate of / min, and the temperature was kept for 2h, and then naturally cooled to obtain 25.8g of activated graphene;

[0075] 24.0 g of activated graphene, 4.0 g of 3-aminopropylethoxysilane, 85.0 g of N,N-dimethylformamide and 1.2 g of triethylamine were weighed and added to a reactor. The temperature of the reactor was raised to 60° C. and the reaction was kept warm for 4 hours. After the temperature of the reactor was lowered to room temperature, the filter cake was collected by filtration and placed in a drying oven at 80° C. and vacuum dried until the filter cake had a constant weight, to obtain 26.4 g of modified graphene.

[0076] Weigh 20.0 g of modified graphene, 12.0 g of terephthaloyl chloride, 110.0 g of N,N-dimethylformamide and 5.0 g of triethylamine and stir at room temperature for 4 hours. After the temperature of the reactor is lowered to room temperature, the filter cake is collected by filtration and placed in a drying oven at 80°C for vacuum drying until the filter cake has a constant weight, to obtain 30.2 g of modified β-nucleating agent.

[0077] S2. Preparation of modified filler

[0078] Weigh 210.0 g of 95 wt% ethanol, 5.6 g of silane coupling agent KH-560 and 28.0 g of modified β-nucleating agent, add them to an ultrasonic device, set the frequency to 40 KHz, and ultrasonicate for 6 hours at room temperature to obtain 212.3 g of dispersion;

[0079] Weigh 10.0 g of expanded graphite, place the expandable graphite in a pulverizer and crush it, pass it through a 60-mesh sieve to obtain expandable graphite powder, place the expandable graphite powder in a tubular furnace, introduce nitrogen protection, and heat the tubular furnace to 805° C. at a rate of 10° C. / min. After keeping the temperature for 3 h, 9.8 g of expanded graphite powder is obtained;

[0080] Weigh 200.0g of dispersion and 8.0g of expanded graphite powder, place the expanded graphite powder in a reactor and stir, set the stirring rate to 400rpm, add the dispersion into an atomizer and spray it onto the expanded graphite powder after atomization at a rate of 24.0g / min. After spraying, continue stirring for 15min, and post-process to obtain 34.8g of modified filler.

[0081] S3. Preparation of modified polypropylene resin

[0082] 30.8 g of 4,4'-diaminostilbene-2,2'-disulfonic acid, 7.7 g of phthalic anhydride, 107.6 g of N,N-dimethylformamide and 3.1 g of triethylamine were weighed and added to a reactor, and stirred at room temperature for 4 h. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a water bath temperature of 100° C., and distilled under reduced pressure until no liquid was produced, to obtain 35.6 g of modified monomer;

[0083] 33.2 g of modified monomer, 33.2 g of styreneethyltrimethoxysilane, 49.8 g of 4,4'-bis(2-sulfonylstyrene)-1,1'-biphenyl, 3.3 g of azobisisobutyronitrile and 149.1 g of dimethyl sulfoxide were weighed and added to a reactor, the reactor temperature was raised to 70° C., and the reaction was kept warm for 4 hours. After the reactor was cooled to room temperature, the reaction liquid was added to a rotary evaporator with a water bath temperature of 100° C., and the reaction liquid was distilled under reduced pressure until no liquid was produced, to obtain 114.3 g of cross-linked polypropylene resin;

[0084] Weigh 88.0 g of cross-linked polypropylene resin and 26.0 g of modified filler and mix them evenly to obtain a composite polypropylene resin. Place the composite polypropylene resin in a tubular furnace and introduce nitrogen protection. The tubular heating furnace is heated to 300° C. at a rate of 10° C. / min, kept warm for 3 hours, and then naturally cooled to room temperature to obtain 113.2 gg modified polypropylene resin.

[0085] S4. Preparation of PP rope

[0086] Weigh 108.0 g of modified polypropylene resin, 4.8 g of tri-tert-butyl hydroxyphenyl acrylate, 8.4 g of polyethylene wax and 8.4 g of silane cross-linked polyethylene ester and mix them evenly to obtain 129.6 g of a mixture;

[0087] 125.0 g of the mixed material was weighed and added to a twin-screw extruder. The temperatures of the eight temperature sections of the twin-screw extruder from the feed port to the discharge port were 260° C., 265° C., 265° C., 270° C., 270° C., 280° C., and 280° C., respectively. The main engine speed of the twin-screw extruder was 120 rpm, and the pressure was 150 bar. 124.2 g of PP filling strip precursor was obtained by melt extrusion.

[0088] Weigh 120.0g of PP filling bar precursor and place it in a high-pressure reactor, place the high-pressure reactor in a salt bath furnace, use carbon dioxide gas to exhaust the air in the high-pressure reactor, use a booster to pass 18MPa carbon dioxide gas into the high-pressure reactor, and raise the temperature of the salt bath furnace to 140°C. Observe the internal pressure of the high-pressure reactor during heating, use valves on both sides to vent and release the pressure, control the pressure in the reactor to be less than 30MPa, keep the reaction warm for 2h, use a pneumatic valve to quickly release the pressure, quickly take out the material and put it in an ice water bath for 20min, then place the material in a drying oven at 80°C and vacuum dry it until the material has a constant weight, to obtain 119.3g of PP filling bars.

[0089] Example 3

[0090] This embodiment provides a method for preparing an environmentally friendly PP filling strip for a submarine cable, comprising the following steps:

[0091] S1. Preparation of modified β nucleating agent

[0092] Weigh 24.0 g of single-layer graphene, place the single-layer graphene in a grinder and grind it through a 100-mesh sieve to obtain single-layer graphene powder. After the single-layer graphene powder is transferred to a reactor, nitrogen is introduced for protection. After the temperature of the reactor is raised to 70°C, the reactor is heated at 50 cm 3 Oxygen was introduced into the reactor at a flow rate of 25 cm / min, and the temperature was kept at room temperature for 2 h. 3 Water vapor was introduced into the reactor at a flow rate of / min, and the temperature was kept for 2h, and then naturally cooled to obtain 24.8g of activated graphene;

[0093] 22.1 g of activated graphene, 3.8 g of 3-aminopropylethoxysilane, 88.0 g of N,N-dimethylformamide and 1.4 g of triethylamine were weighed and added to a reactor. The temperature of the reactor was raised to 50° C. and the reaction was kept warm for 3 h. After the temperature of the reactor was lowered to room temperature, the filter cake was collected by filtration and placed in a drying oven at 80° C. and vacuum dried until the filter cake had a constant weight, to obtain 23.8 g of modified graphene.

[0094] Weigh 22.1 g of modified graphene, 10.2 g of terephthaloyl chloride, 112.0 g of N,N-dimethylformamide and 4.8 g of triethylamine and stir at room temperature for 3 h. After the temperature of the reactor is lowered to room temperature, the filter cake is collected by filtration and placed in a drying oven at 80°C for vacuum drying until the filter cake has a constant weight, to obtain 31.2 g of modified β-nucleating agent.

[0095] S2. Preparation of modified filler

[0096] Weigh 211.0 g of 95 wt% ethanol, 5.6 g of silane coupling agent KH-560 and 28.0 g of modified β-nucleating agent, add them to an ultrasonic device, set the frequency to 30 KHz, and ultrasonicate for 5 h at room temperature to obtain 210.2 g of dispersion;

[0097] Weigh 10.0 g of expandable graphite, place the expandable graphite in a grinder and grind it, pass it through a 60-mesh sieve to obtain expandable graphite powder, place the expandable graphite powder in a tubular furnace, introduce nitrogen protection, raise the temperature of the tubular furnace to 800° C. at a rate of 10° C. / min, and keep it warm for 2 h to obtain 9.8 g of expandable graphite powder;

[0098] Weigh 200.0g of the dispersion and 9.5g of expanded graphite powder, place the expanded graphite powder in a reactor and stir, set the stirring rate to 375rpm, add the dispersion into an atomizer and spray it onto the expanded graphite powder at a rate of 16.0g / min. After spraying, continue stirring for 15min, and post-treat to obtain 32.5g of modified filler.

[0099] S3. Preparation of modified polypropylene resin

[0100] Weigh 40.0 g of 4,4'-diaminostilbene-2,2'-disulfonic acid, 12.0 g of phthalic anhydride, 160.0 g of N,N-dimethylformamide and 3.6 g of triethylamine into a reactor, stir at room temperature for 4 h, and after the reactor is cooled to room temperature, add the reaction solution into a rotary evaporator with a water bath temperature of 90°C, and distill under reduced pressure until no liquid is produced, to obtain 50.3 g of modified monomer;

[0101] 40.0 g of modified monomer, 38.5 g of styreneethyltrimethoxysilane, 40.0 g of 4,4'-bis(2-sulfonylstyrene)-1,1'-biphenyl, 3.6 g of azobisisobutyronitrile and 180.0 g of dimethyl sulfoxide were weighed and added to a reactor, the reactor temperature was raised to 60° C., and the reaction was kept warm for 3 hours. After the reactor was cooled to room temperature, the reaction solution was added to a rotary evaporator with a water bath temperature of 90° C., and the reaction solution was distilled under reduced pressure until no liquid was produced, to obtain 115.5 g of cross-linked polypropylene resin;

[0102] Weigh 96.0 g of cross-linked polypropylene resin and 24.0 g of modified filler and mix them evenly to obtain a composite polypropylene resin. Place the composite polypropylene resin in a tubular furnace and introduce nitrogen protection. After the tubular heating furnace is increased to 305°C at a rate of 10°C / min, it is kept warm for 3 hours and then naturally cooled to room temperature to obtain 119.5 g of modified polypropylene resin.

[0103] S4. Preparation of PP rope

[0104] Weigh 115.0 g of modified polypropylene resin, 3.6 g of tri-tert-butyl hydroxyphenyl acrylate, 6.4 g of polyethylene wax and 6.4 g of silane cross-linked polyethylene ester and mix them uniformly to obtain 131.4 g of a mixture;

[0105] 125.0 g of the mixed material was weighed and added to a twin-screw extruder. The temperatures of the eight temperature sections of the twin-screw extruder from the feed port to the discharge port were 260° C., 265° C., 265° C., 270° C., 270° C., 280° C., and 280° C., respectively. The main engine speed of the twin-screw extruder was 100 rpm, and the pressure was 125 bar. 124.2 g of PP filling strip precursor was obtained by melt extrusion.

[0106] Weigh 120.0g of PP filling bar precursor and place it in a high-pressure reactor, place the high-pressure reactor in a salt bath furnace, use carbon dioxide gas to exhaust the air in the high-pressure reactor, use a booster to pass 16MPa carbon dioxide gas into the high-pressure reactor, and raise the temperature of the salt bath furnace to 120°C. Observe the internal pressure of the high-pressure reactor during heating, use valves on both sides to vent and release the pressure, control the pressure in the reactor to be less than 30MPa, keep the reaction warm for 2h, use a pneumatic valve to quickly release the pressure, quickly take out the material and put it in an ice water bath for 20min, then place the material in a drying oven at 80°C and vacuum dry it until the material has a constant weight, to obtain 119.2g of PP filling bars.

[0107] Comparative Example 1

[0108] The difference between this comparative example and Example 3 is that step S1 is eliminated, and in step S2, an equal amount of TMB-5 is used to replace the modified β-nucleating agent.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 3 is that step S1 and step S2 are eliminated, and in step S3, an equal amount of TMB-5 is used to replace the modified filler.

[0111] Comparative Example 3

[0112] The difference between this comparative example and Example 3 is that the step of preparing cross-linked polypropylene in step S3 is eliminated, and in step S3, an equal amount of homopolypropylene resin is used to replace the cross-linked polypropylene resin.

[0113] Comparative Example 4

[0114] The difference between this comparative example and Example 3 is that step S1, step S2 and step S3 are eliminated, and in step S4, an equal amount of homopolypropylene is used to replace the modified polypropylene resin.

[0115] Performance testing:

[0116] The chemical stability, high temperature resistance, whiteness, wear resistance and toughness of the PP filling strips for submarine cables prepared in Examples 1-3 and Comparative Examples 1-3 were tested. The chemical stability was tested in accordance with the corrosion resistance of the test specimens in accordance with the standard HG / T 3984-2007 "Chemically resistant modified polypropylene storage tanks".

[0117] The toughness is measured by referring to the standards GB / T 12670-2008 "Polypropylene (PP) resin" and FZ / T 52033-2014 "Polyethylene / polypropylene (PE / PP) whitening composite short fibers" to determine the bending modulus, tensile yield stress, simply supported beam notched impact strength and linear density deviation rate of the sample;

[0118] The whiteness value of the sample is measured according to the whiteness standard FZ / T 52033-2014 "Polyethylene / polypropylene (PE / PP) whitening composite short fiber"; the wear resistance of the cable material is tested according to the wear resistance standard GB / T 17737.324-2018 "Coaxial communication cable Part 1-324: Mechanical test method Cable wear resistance test";

[0119] The high temperature resistance performance refers to the standard GB / T 2951.42-2008 "General test methods for insulation and sheath materials of electric cables and optical cables Part 42: Special test methods for polyethylene and polypropylene mixtures, tensile strength and elongation at break test after high temperature treatment, winding test after high temperature treatment, winding test after air heat aging, determination of mass increase, long-term thermal stability test, copper catalytic oxidation degradation test method". After Example 3 and Comparative Examples 1-3 were treated at 100°C for 42 days, their chemical stability, high temperature resistance, whiteness, wear resistance and toughness were tested twice. The specific test data are shown in Table 1-2:

[0120] Table 1-Performance test data of the sample

[0121]

[0122] Table 2- Performance test data of samples after high temperature treatment

[0123]

[0124] Data Analysis:

[0125] Comparative analysis of the data in Table 1 above shows that the PP filling strip for submarine cable prepared by the present invention is resistant to corrosion by saturated calcium hydroxide and 10wt% nitric acid solution, with a bending modulus of 34.2MPa, a tensile yield stress of 843.2MPa, and a simply supported beam notched impact strength of 55.6kJ / m at 23°C. 2 , the notched impact strength of the simply supported beam at -20℃ is 7.5kJ / m 2 , the linear density deviation rate is 2.3%, the whiteness value is 118.83, and the number of blade scraping cycles is 156 times.

[0126] By comparing the data of Example 3, Comparative Example 1 and Comparative Example 2, it can be found that the mechanical properties of the PP filling strips prepared using the modified filler prepared by the present invention, such as bending modulus, tensile yield stress and linear density difference, are significantly improved compared with the PP filling strips prepared by Comparative Example 1 and Comparative Example 2, indicating that the modified filler prepared by the present invention, as a β-nucleating agent, heat conduction auxiliary material and foaming agent, significantly improves the mechanical properties of the PP filling strips.

[0127] By comparing the data of Example 3, Comparative Example 3 and Comparative Example 4, it can be found that the chemical stability and whiteness value of the PP filling strip prepared by using the modified polypropylene resin prepared by the present invention are significantly improved compared with the PP filling strips prepared by Comparative Examples 3 and 4, indicating that the modified polypropylene resin prepared by using the modified monomer, silane coupling agent and fluorescent monomer in the present invention has extremely strong chemical stability, and its performance is significantly improved after being mixed with the modified filler and auxiliary materials for foaming.

[0128] Comparing and analyzing the data in Table 2 above, the PP filling strip for submarine cable prepared by the present invention is resistant to corrosion by saturated calcium hydroxide and 10wt% nitric acid solution after heat treatment, and the bending modulus reaches 31.3MPa, the tensile yield stress is 821.5MPa, and the simply supported beam notched impact strength at 23°C is 53.1kJ / m 2 The notched impact strength of the simply supported beam at -20°C is 6.8 kJ / m 2 , the linear density deviation rate is 2.4%, the whiteness value is 109.35, and the number of blade scraping cycles is 143 times.

[0129] By comparing the data in Table 2, it can be found that the modified filler prepared by the present invention and the cross-linked polypropylene resin cooperate with each other, which promotes the polyimide reaction of the cross-linked polypropylene resin at high temperature, and at the same time, acts as a β nucleating agent to transform the polypropylene resin crystal form into the β type. Its efficient thermal conductivity makes the reaction proceed evenly and fully, and the generated imide group enhances the thermal stability of the modified polypropylene resin. The high porosity inside it also acts as a gas release center to promote bubbles, making the foaming more sufficient and uniform, and finally improving the high temperature resistance and mechanical properties of the PP filling strip.

[0130] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0131] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0132] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An environmentally friendly PP filling strip for submarine cables, characterized in that: The invention comprises 100-120 parts by weight of modified polypropylene resin, 1-5 parts by weight of antioxidant, 5-10 parts by weight of lubricant and 5-10 parts by weight of seawater protective agent; The preparation method of the modified polypropylene resin is as follows: 80-100 parts of cross-linked polypropylene resin and 20-30 parts of modified filler are weighed by weight and mixed evenly to obtain a composite polypropylene resin, the composite polypropylene resin is placed in a tubular furnace, nitrogen is introduced for protection, the tubular heating furnace is heated to 300±5°C at a rate of 10°C / min, and after keeping warm for 2-3 hours, it is naturally cooled to room temperature to obtain the modified polypropylene resin.

2. The environmentally friendly PP filling strip for submarine cables according to claim 1 is characterized in that: The preparation method of the cross-linked polypropylene resin is as follows: 4-6 parts of modified monomers, 3-5 parts of styrene ethyl trimethoxy silane, 4-6 parts of 4,4'-bis(2-sulfonyl styrene)-1,1'-biphenyl, 0.3-0.5 parts of azobisisobutyronitrile and 15-20 parts of dimethyl sulfoxide are weighed by weight and added into a reaction kettle, the temperature of the reaction kettle is increased to 50-70°C, the reaction is kept warm for 2-4 hours, and the cross-linked polypropylene resin is obtained by post-treatment.

3. The environmentally friendly PP filling strip for submarine cables according to claim 2 is characterized in that: The preparation method of the modified monomer is as follows: 20-30 parts by weight of 4,4'-diaminostilbene-2,2'-disulfonic acid, 5-10 parts of phthalic anhydride, 75-100 parts of N,N-dimethylformamide and 1-3 parts of triethylamine are added into a reaction kettle, stirred at room temperature for 2-4 hours, and post-treated to obtain the modified monomer.

4. The environmentally friendly PP filling strip for submarine cables according to claim 1, characterized in that: The preparation method of the modified filler comprises the following steps: A1. Weigh 150-180 parts of 95wt% ethanol, 3-5 parts of silane coupling agent KH-560 and 10-20 parts of modified β-nucleating agent by weight, add them into an ultrasonic device, set the frequency to 20-40KHz, and ultrasonicate for 4-6h at room temperature to obtain a dispersion; A2, placing the expandable graphite in a pulverizer and crushing it, passing it through a 60-mesh sieve to obtain expandable graphite powder, placing the expandable graphite powder in a tubular furnace, introducing nitrogen protection, raising the temperature of the tubular furnace to 800±5°C at a rate of 10°C / min, and keeping the temperature for 2-3h to obtain expandable graphite powder; A3. Weigh 20-30 parts of dispersion and 1-2 parts of expanded graphite powder by weight, place the expanded graphite powder in a reactor and stir, set the stirring rate to 350-400 rpm, add the dispersion into an atomizer and spray it onto the expanded graphite powder at a rate of 1-3 parts / min. After spraying, continue stirring for 10-15 minutes, and post-treat to obtain a modified filler.

5. The environmentally friendly PP filling strip for submarine cables according to claim 4, characterized in that: The preparation method of the modified β nucleating agent is as follows: 10-15 parts of modified graphene, 5-8 parts of terephthaloyl chloride, 50-60 parts of N,N-dimethylformamide and 2-3 parts of triethylamine are weighed by weight, stirred at room temperature for 2-4 hours, and post-treated to obtain the modified β nucleating agent.

6. The environmentally friendly PP filling strip for submarine cables according to claim 5, characterized in that: The preparation method of modified graphene is as follows: 10-20 parts of activated graphene, 1-2 parts of 3-aminopropylethoxysilane, 40-50 parts of N,N-dimethylformamide and 0.5-0.8 parts of triethylamine are weighed and added into a reaction kettle, the temperature of the reaction kettle is increased to 40-60° C., the reaction is kept warm for 2-4 hours, and the modified graphene is obtained by post-treatment.

7. The environmentally friendly PP filling strip for submarine cables according to claim 6, characterized in that: The preparation method of activated graphene is as follows: a single-layer graphene is placed in a pulverizer and crushed, and passed through a 100-mesh screen to obtain a single-layer graphene powder. After the single-layer graphene powder is transferred to a reactor, nitrogen is introduced for protection. After the temperature of the reactor is raised to 60-80°C, the reactor is heated at 50 cm 3 Oxygen was introduced into the reactor at a flow rate of 25 cm / min, and the temperature was kept at 1-2 h. 3 Water vapor is introduced into the reactor at a flow rate of 100 Å / min, the temperature is kept for 1-2 h, and the reactor is naturally cooled to obtain activated graphene.

8. The environmentally friendly PP filling strip for submarine cables according to claim 1, characterized in that: The antioxidant is one or more of tri-tert-butyl hydroxyphenyl acrylate, tetramethyl dihydroxyphenyl acrylate and tri-tert-butyl hydroxyphenyl acrylate; the seawater protective agent is one or more of polyurethane elastomer, polymer modified oil and silane cross-linked polyethylene ester; the lubricant is one or more of lead stearate, distearic acid glycerol and polyethylene wax.

9. A method for preparing an environmentally friendly PP filling strip for submarine cables according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. uniformly mixing the modified polypropylene resin, the antioxidant, the lubricant and the seawater protective agent to obtain a mixture; S2. Add the mixed material into a twin-screw extruder, wherein the temperatures of the eight temperature sections of the twin-screw extruder from the feed port to the discharge port are 260° C., 265° C., 265° C., 270° C., 270° C., 280° C., and 280° C., respectively, and the main engine speed of the twin-screw extruder is 80-120 rpm, and the pressure is 100-150 bar, and the PP filling strip precursor is obtained by melt extrusion; S3. Place the PP filling strip precursor in a high-pressure reactor, place the high-pressure reactor in a salt bath furnace, use carbon dioxide gas to exhaust the air in the high-pressure reactor, and use a booster device to introduce 15-18MPa carbon dioxide gas into the high-pressure reactor. The temperature of the salt bath furnace rises to 100-140°C. During the heating process, observe the internal pressure of the high-pressure reactor, use valves on both sides to vent and release the pressure, control the pressure in the reactor to be less than 30MPa, keep the reaction warm for 1-2h, and post-treat to obtain the foamed PP filling strip.

Images