CN107325411B

CN107325411B - Flame-retardant antistatic random copolymerization polypropylene composition and pipe

Info

Publication number: CN107325411B
Application number: CN201610283968.9A
Authority: CN
Inventors: 徐耀辉; 毕福勇; 吕明福; 郭鹏; 张师军; 邹浩; 解娜; 白弈青; 杨庆泉; 邵静波
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2016-04-29
Filing date: 2016-04-29
Publication date: 2020-09-15
Anticipated expiration: 2036-04-29
Also published as: CN107325411A

Abstract

The invention relates to a flame-retardant antistatic random copolymerization polypropylene composition, which comprises a base random copolymerization polypropylene resin, a flame retardant and a conductive filler, wherein the base random copolymerization polypropylene resin comprises a random copolymerization polypropylene continuous phase and a rubber dispersed phase of a propylene-ethylene copolymer, wherein the random copolymerization polypropylene continuous phase at least comprises a first random copolymerization polypropylene and a second random copolymerization polypropylene, and the first random copolymerization polypropylene and the second random copolymerization polypropylene are respectively and independently selected from a propylene/ethylene random copolymer, a propylene/butylene random copolymer and an ethylene/propylene/butylene ternary random copolymer; the content of xylene solubles at room temperature in the base random copolymer polypropylene resin is more than 10% by weight and less than 35% by weight; the ratio of the Mw of the room temperature trichlorobenzene soluble matter to the Mw of the room temperature trichlorobenzene insoluble matter is greater than 0.4 and less than 1. The invention also relates to a pipe prepared from the composition, a preparation method and the like.

Description

Flame-retardant antistatic random copolymerization polypropylene composition and pipe

Technical Field

The invention relates to the field of macromolecules, in particular to a flame-retardant antistatic high-melt-strength polypropylene composition, a flame-retardant antistatic high-low temperature impact PP-R pipe and a preparation method thereof.

Background

The polypropylene pipe materials are mainly divided into homo-polypropylene (PP-H), block copolymer polypropylene (PP-B) and random copolymer polypropylene (PP-R), and the structural difference of the three materials enables the three materials to have different application characteristics, so that the materials have different purposes. The PP-R has good impact resistance and high-temperature creep resistance, so that the PP-R can be suitable for underground pipes of coal mines and used for replacing the existing metal pipes. Thereby reducing material cost, reducing construction strength, increasing service life, and the like.

However, plastic pipes are insulating materials and are very prone to generate static electricity. When the suspended coal powder or other dust and the surface of the PP-R pipe are in mutual friction collision, positive and negative charges are redistributed between the suspended coal powder or other dust and respectively accumulated on the surface of the PP-R pipe and the dust. When the static charge is accumulated to a certain extent, a spark is discharged, and there is a possibility that a fire or a gas explosion is caused. PP-R pipes also have the disadvantage of being flammable, pressure-resistant and impact-resistant, compared with metal pipes. In order to safely and reliably apply the PP-R pipe to special fields such as coal mine underground, the flame retardant, antistatic and mechanical properties of the PP-R pipe must be improved. However, flame retardant and antistatic modification of PP-R requires the addition of large amounts of flame retardant and antistatic agent, respectively. The compatibility of the auxiliary agent with PP-R is not good, and stress concentration and crystallization defects are generated in matrix resin after molding. A large amount of additive particles can enter between polypropylene molecular chains to play a role in 'lubricating' winding and entanglement between the molecular chains, so that the melt strength of the polypropylene is reduced. The mechanical properties and processability of PP-R are greatly reduced by the factors. There is a need to find an antistatic agent that can act synergistically on flame retardancy, thereby reducing the amount of additives added, and to use a matrix resin with higher initial mechanical properties and melt strength, thereby ensuring that, after modification, the PP-R composition and PP-R pipe still have acceptable processability and mechanical properties.

In the prior art, the performance of the random copolymerization polypropylene is improved by post processing modification, such as the improvement of the impact strength of the PP-R pipe material by adding a beta crystal nucleating agent. Patent CN101168609A mentions that modifying random polypropylene pipe material with a beta-crystal nucleating agent simultaneously increases the stiffness and toughness of the random polypropylene pipe material. However, the beta nucleating agent has high cost, and beta crystals are unstable and are easy to be transformed into alpha crystals in a service cycle, so that the performance of the material is reduced. In the patent, CN201310319479 proposes a method for preparing a low-temperature impact resistant PP-R pipe material, but a method for preparing a high-performance pipe material by blending random copolymer polypropylene and block copolymer polypropylene undoubtedly also causes the increase of production cost and the instability of material performance caused by raw material quality, modification operation and the like.

In addition to impact properties, the melt strength of random copolymer polypropylene also has a large impact on pipe processing. The softening point of the general random copolymerization polypropylene is close to the melting point, and when the temperature is higher than the melting point, the melt strength and the viscosity of the melt are reduced sharply, so that the melt fracture is easy to occur, and the surface of a product is rough when an extruded pipe is molded. The wall thickness is not uniform, and problems such as edge curl and shrinkage occur. Meanwhile, under the condition of higher traction speed, the rotating speed and the torque of a screw of the extruder are greatly improved, and the energy consumption and the equipment load are increased. Therefore, it is a trend to develop new random copolymerized polypropylene pipe material with high melt strength and less sensitivity to temperature and Melt Flow Rate (MFR).

A common practice to increase the melt strength of polypropylene is to lower the melt index, i.e. increase the polypropylene molecular weight, but this can lead to difficulties in melting and extruding the material. Another method is to broaden the molecular weight distribution, for example, US7365136 and US6875826 report a method for preparing homo-and random-copolymerized polypropylene with wide molecular weight distribution and high melt strength, which selects alkoxysilane as an external electron donor (such as dicyclopentyldimethoxysilane), and regulates the molecular weight and distribution by adjusting the hydrogen concentration in a plurality of reactors connected in series, thereby achieving the effect of improving the melt strength of polypropylene. WO9426794 discloses a process for the production of high melt strength homo-and atactic polypropylene in multiple reactors in series by adjusting the hydrogen concentration in the different reactors to produce high melt strength polypropylene with a broad molecular weight distribution or bimodal distribution, the properties of the catalyst being not adjusted in the individual reactors, so that a large amount of hydrogen is required for the production process.

At present, there are some methods for preparing high melt strength polypropylene, such as CN102134290, CN102134291 and 201210422726.5, but the performance of the obtained polypropylene needs to be further improved.

Disclosure of Invention

The invention aims to overcome the defects that the existing PP-R pipe material has poor flame retardance and poor antistatic property when being used for preparing a PP-R pipe, and the mechanical property of a pipe product is greatly reduced after conventional flame-retardant antistatic modification, so that the pipe product is not suitable for meeting the requirements of special fields such as underground coal mines, and the like, and provides a novel random copolymerization polypropylene composition and a high-performance flame-retardant antistatic PP-R pipe prepared from the random copolymerization polypropylene composition.

According to the invention, the random copolymerization polypropylene which has excellent high melt strength, high and low temperature and high impact resistance is taken as the base resin, so that after a certain amount of flame-retardant and antistatic modification auxiliary agent is added, a flame-retardant antistatic PP-R composition still having high processability and mechanical properties can be obtained, and the high-performance flame-retardant antistatic PP-R pipe is prepared from the composition. Meanwhile, the PP-R pipe with excellent flame retardance, antistatic property, impact resistance and excellent pipe extrusion processing performance can be prepared by using a general pipe extrusion process. The manufacturing process is simple and convenient, saves energy and is environment-friendly.

One of the purposes of the invention is to provide a high-performance flame-retardant antistatic PP-R composition. The composition includes a base PP-R resin, a flame retardant, and a conductive filler. After intensive research, the inventor of the invention discovers that when the polypropylene composition obtained by matching the basic PP-R resin, the flame retardant and the conductive filler is used for manufacturing a pipe by adopting a general double-screw pipe extrusion process, the polypropylene composition has the advantages of high extrusion speed and low screw torque, meets the economic requirement of the existing modified PP-R pipe extrusion process, and the obtained modified PP-R pipe also has excellent flame retardant property, antistatic property and impact resistance, is suitable for the requirement of underground coal mine pipelines, and has great industrial application prospect. The basic PP-R resin is random copolymerization polypropylene which has high melt strength, high and low temperature and high impact resistance. The invention also provides a preparation method of the composition containing the PP-R resin.

As a base resin (i.e., a base PP-R resin) of the polypropylene composition, a random copolymerized polypropylene continuous phase and a rubber dispersed phase of a propylene-ethylene copolymer, wherein the random copolymerized polypropylene continuous phase includes at least a first random copolymerized polypropylene and a second random copolymerized polypropylene, each of which is independently selected from the group consisting of a propylene/ethylene random copolymer, a propylene/butene random copolymer and an ethylene/propylene/butene terpolymer; the content of xylene solubles at room temperature in the base random copolymer polypropylene resin is more than 10% by weight and less than 35% by weight; the ratio of the Mw of the room temperature trichlorobenzene soluble matter to the Mw of the room temperature trichlorobenzene insoluble matter is greater than 0.4 and less than 1.

The composition has good flame retardant property and antistatic property, high and low temperature impact resistance, higher solvent strength and optimized rigidity and toughness.

According to a preferred embodiment of the present invention, a base PP-R resin with better rigidity and toughness is obtained when the ethylene content in the room temperature xylene solubles is less than 50% by weight, and more than 28% by weight.

According to the composition provided by the invention, the molecular weight distribution M of the basic PP-R resin_w/M_nLess than or equal to 10 and greater than or equal to 4; m_z+1/M_wGreater than 10 and less than 20. The ethylene content in the base PP-R resin is 8-20 wt%. According to the invention, the basic PP-R resin has a molecular weight Polydispersity Index (PI) of between 4 and 10.

The melt index of the base PP-R resin of the present invention is preferably controlled in the range of 0.1 to 15g/10min, and more preferably 0.1 to 6.0g/10min, to achieve a higher melt strength. The melt index was measured at 230 ℃ under a load of 2.16 kg.

Through a large number of experiments, the inventor of the invention finds that in the basic PP-R resin, the weight ratio of the propylene-ethylene copolymer rubber dispersed phase to the random polypropylene continuous phase is 11-80:100, and the rigidity and toughness balance effect is better.

According to the invention, the ethylene content in the random copolymerized polypropylene continuous phase is 0 to 6% by weight, such as 0.1 to 6% by weight; and/or butene content is 0-10 wt%, such as 0.1-10 wt%.

In a preferred embodiment, the ratio of the melt index of the random copolymer polypropylene continuous phase to the base PP-R resin is controlled to be greater than or equal to 0.6 and less than 1.

According to a particular embodiment of the composition according to the invention, the random copolymer polypropylene continuous phase has the following characteristics: molecular weight distribution Mw/Mn is 6-20; mz +1/Mn is greater than or equal to 70 and less than 150. Wherein the fraction having a molecular weight of more than 500 ten thousand is contained in an amount of 1.5% by weight or more and 5% by weight or less; the content of the fraction having a molecular weight of less than 5 ten thousand is not less than 15.0% by weight and not more than 40% by weight.

According to another specific embodiment of the composition of the present invention, the weight ratio of the first random copolymer polypropylene and the second random copolymer polypropylene is 40:60 to 60: 40.

According to another specific embodiment of the composition of the present invention, the first random copolymer polypropylene has a melt index less than the melt index of the second random copolymer polypropylene. In a preferred embodiment, the first random copolymer polypropylene preferably has a melt index of 0.001 to 0.4g/10min as measured at 230 ℃ under a load of 2.16 kg. The random copolymerized polypropylene of the random copolymerized polypropylene continuous phase has a melt index of 0.1 to 15g/10min measured at 230 ℃ under a load of 2.16 kg; preferably 0.1-6g/10 min.

According to another particular embodiment of the composition according to the invention, the ethylene content in the random copolymerized polypropylene continuous phase is from 0 to 6% by weight, preferably from 0.1 to 6% by weight; and/or a butene content of 0 to 10% by weight, preferably 0.1 to 10% by weight.

According to the present invention, there is provided a base PP-R resin prepared by performing a random copolymerization of propylene groups in the presence of a first random copolymerized polypropylene to obtain a random copolymerized polypropylene continuous phase comprising the first random copolymerized polypropylene and a second random copolymerized polypropylene, and then performing a propylene-ethylene copolymerization in the presence of the random copolymerized polypropylene continuous phase to obtain a material comprising a propylene-ethylene copolymer. It can be seen that the base PP-R resin of the present invention is not simply a mixture of a continuous phase of random copolymerized polypropylene and a dispersed phase of propylene-ethylene copolymer rubber, but is a material having an integral structure obtained by further performing a propylene-ethylene copolymerization reaction on the basis of the continuous phase of random copolymerized polypropylene.

The basic PP-R resin also has good heat resistance and good heat sealing performance, and the melting peak temperature T of the final polypropylene resin is measured by DSC_m145 ℃ or higher and 158 ℃ or lower.

In the preparation method of the basic PP-R resin, the added second external electron donor can react with the catalytic activity center in the copolymerization product material of propylene and ethylene and/or 1-butene in the first stage to generate a new catalytic activity center, and the propylene and the ethylene and/or 1-butene are continuously initiated to polymerize into a copolymerization polymer with a molecular weight which is different from that of the product obtained in the first stage in the second stage. The second external electron donor has higher hydrogen response than the first external electron donor, and can prepare a high melt index polymer in the presence of a small amount of hydrogen. It is then important to control the molecular weight of the resulting polymer by controlling the reaction conditions of the second polymerization step. The second external electron donor with good hydrogen regulation sensitivity added in the second stage in the first step is utilized to obtain the rubber phase molecular weight matched with the continuous phase under the specific hydrogen concentration, so that the polypropylene material with good performance is obtained, which is one of the outstanding advantages of the invention. The composition and structure control of the rubber phase component ensures that the rubber phase component has high melt strength, the specific content of the rubber component ensures that the rubber phase component has higher impact resistance, and in addition, the proper molecular weight distribution also ensures that the polymer has good processability. That is, the present invention obtains a base resin (i.e., a base PP-R resin) having excellent properties on the basis of controlling the properties of the produced continuous phase and rubber dispersed phase and their combination by setting a plurality of propylene random copolymerization stages to prepare the continuous phase and selecting appropriate individual reaction parameters and reaction conditions for the continuous phase and rubber dispersed phase preparation steps.

According to a preferred embodiment of the polypropylene composition provided by the invention, in order to meet the requirements of the market on environmental protection and safety, the flame retardant is a halogen-free flame retardant. The halogen-free flame retardant may be a conventional choice in the art, and for example, may be a phosphorus-based flame retardant such as APP and the like; inorganic flame retardants such as magnesium hydroxide, aluminum hydroxide, silicates, zinc borate, and the like; the material is organic Intumescent Flame Retardant (IFR), such as physically intumescent graphite flame retardant or chemically intumescent composite flame retardant, wherein the acid source of the chemically intumescent composite flame retardant can be phosphate, sulfate, phosphate and the like, the carbon source can be pentaerythritol, glycol and the like, and the foaming source can be urea, dicyandiamide, polyamide, trichlorocyanamide and the like. In a specific embodiment, the weight of the flame retardant is 10-50 parts, for example, 10-50 parts, preferably 25-40 parts, based on 100 parts by weight of the base PP-R resin.

According to another preferred embodiment of the polypropylene composition provided by the present invention, the conductive filler is selected from carbon materials in view of the synergistic effect with the flame retardant, which contributes to the formation of a dense carbon layer that blocks flame and materials, and thus can reduce the amount of the flame retardant to be added. For example, the conductive material may be a kind commonly used in the field of carbon materials, and may be at least one of carbon black, graphite, carbon nanotube, and carbon fiber. Wherein the carbon black comprises at least one of acetylene black, superconducting carbon black, and specific conductive carbon black. The graphite includes at least one of natural graphite, expandable graphite, expanded graphite, graphene, and the like. The carbon nanotubes comprise single-walled carbon nanotubes and/or multi-walled carbon nanotubes that are not surface-modified or surface-modified. The method of surface modification is well known to those skilled in the art and will not be described herein. In a particular embodiment, the electrically conductive filler is present in an amount of 0.1 to 10 parts, preferably 0.75 to 3 parts, such as 2 to 3 parts, based on 100 parts by weight of the base PP-R resin.

According to some embodiments of the polypropylene composition provided herein, preferably, the polypropylene composition further comprises a lubricant, which improves the extrusion processability of the polypropylene composition. The type and amount of the lubricant may be conventionally selected in the art, and for example, the lubricant may be selected from at least one of polyethylene glycol (PEG) type lubricant, fluoropolymer type lubricant, silicone type lubricant, fatty alcohol type lubricant, fatty acid ester type lubricant, stearic acid amide type lubricant, fatty acid metal soap type lubricant, alkane and alkane oxide type lubricant, and micro-nano particle type lubricant. Specifically, the PEG-based lubricant may be, for example, PEG molecule with molecular weight of 500-50000, which may be subjected to capping, grafting, crosslinking treatment, or other chemical or physical modification. The fluoropolymer lubricant may be at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, and the like, or may be another unimodal or multimodal fluoropolymer or a crystalline or semicrystalline fluoropolymer. The organic silicon lubricant can be various compounds which take carbon and silicon atoms as molecular main chains and take oligomers or oligomers of organic groups such as methyl, phenyl, alkoxy, vinyl and the like as side chains. The fatty alcohol-based lubricant may be, for example, at least one of a soft fatty alcohol, a hard fatty alcohol, a tallow fatty alcohol, and the like. The fatty acid based lubricant may be, for example, stearic acid and/or 12-hydroxystearic acid. The fatty acid ester lubricant may be at least one of butyl stearate, monoglyceride stearate, cetyl palmitate, stearyl stearate, and the like. The stearamide-based lubricant may be, for example, at least one of stearamide, oleamide, erucamide, n-Ethylenebisstearamide (EBS), and the like. The fatty acid metal soap lubricant may be at least one of lead stearate, calcium stearate, magnesium stearate, synthetic calcium acetate, and the like. The alkane and the oxidized alkane lubricant may be at least one of liquid paraffin, solid paraffin, polyethylene wax, polypropylene wax, ethylene oxide wax, and the like. The micro-nano particle lubricant can be powder rubber and/or silica gel particles. Further, the lubricant may be present in an amount of 0.05 to 5 parts by weight, preferably 0.5 to 3 parts by weight, such as 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total base PP-R resin.

In addition, the polypropylene composition can also contain various other additives which are commonly used in polypropylene resin and polypropylene pipes and do not have adverse effects on the extrusion performance, the flame retardant performance, the antistatic performance and the mechanical performance of the polypropylene composition provided by the invention. Such other additives include, but are not limited to: at least one of antioxidant, slipping agent, and anti-sticking agent. In addition, the amount of the other additives can be selected conventionally in the art, and those skilled in the art can know the amount and will not be described herein.

In one embodiment of the present invention, the composition is a halogen-free flame retardant antistatic PP-R composition, and comprises the following components in percentage by weight: the above base PP-R resin: 100 portions of conductive filler, 0.1 to 10 portions, preferably 0.75 to 3 portions; halogen-free flame retardant: 10-50 parts, preferably 25-40 parts; lubricant: 0.05 to 5 parts by weight, preferably 0.1 to 0.5 part.

The high-performance flame-retardant antistatic PP-R composition (such as a halogen-free flame-retardant antistatic PP-R composition) provided by the invention has excellent mechanical strength and processability, qualified optical performance and excellent antistatic performance. The high-performance (halogen-free) flame-retardant antistatic PP-R composition has the following performances: the impact strength of the gap of the simply supported beam is more than or equal to 15MPa, preferably more than or equal to 25 MPa; the oxygen index is 25 or more, preferably 28 or more, e.g., 25 to 40. Further, the surface resistivity of the flame-retardant antistatic composition sample sheet was 10⁴-10⁹Omega, preferably 10⁴-10⁷Ω。

According to another object of the present invention, there is also provided a method for preparing the above composition, comprising the steps of:

the first step is as follows: the preparation of the random copolymerization polypropylene continuous phase,

the first stage is as follows: copolymerizing propylene with ethylene and/or butene in the presence or absence of hydrogen in the presence of a Ziegler-Natta catalyst comprising a first external electron donor to obtain a first random copolymer polypropylene containing stream;

and a second stage: adding a second external electron donor to react with the catalyst in the material flow in the first stage, and then copolymerizing propylene and ethylene and/or butylene in the presence of the first random copolymerization polypropylene and hydrogen to prepare second random copolymerization polypropylene so as to obtain a random copolymerization polypropylene continuous phase material flow containing the first random copolymerization polypropylene and the second random copolymerization polypropylene;

wherein the hydrogen response of the second external electron donor is higher than the hydrogen response of the first external electron donor;

the second step is that: performing a propylene-ethylene copolymerization reaction in the presence of the continuous phase stream of random copolymer polypropylene obtained in the first step and hydrogen to produce a propylene-ethylene copolymer rubber phase, resulting in a high melt strength impact polypropylene comprising the continuous phase and the rubber phase;

the third step: and blending the obtained basic random copolymerization polypropylene resin, a flame retardant and a conductive filler to obtain the composition.

According to the present invention, there is provided a base random copolymer polypropylene resin prepared by subjecting to random copolymerization in the presence of a first random copolymer polypropylene to obtain a random copolymer polypropylene continuous phase comprising a first random copolymer polypropylene and a second random copolymer polypropylene, then subjecting to propylene-ethylene copolymerization in the presence of the random copolymer polypropylene continuous phase and a catalyst for preparing the continuous phase to obtain a material comprising a propylene-ethylene copolymer rubber phase, and then subjecting to foaming. It can be seen that the base resin in the present invention is not simply mixed of the continuous phase of random copolymerized polypropylene and the dispersed phase of propylene-ethylene copolymer rubber, but is a unitary polypropylene material (base PP-R resin) comprising a continuous phase of propylene random copolymer and a dispersed phase of propylene-ethylene copolymer rubber obtained after further propylene-ethylene copolymerization is performed on the basis of the continuous phase of random copolymerized polypropylene.

In the preparation method of the composition, the external electron donor with good hydrogen-adjusting sensitivity added in the first step is utilized to obtain the rubber phase molecular weight matched with the continuous phase under the specific hydrogen concentration, so that the base resin with good performance is obtained, which is one of the outstanding advantages of the invention. The composition and structure control of the rubber phase component ensures that the rubber phase component has high melt strength, the specific content of the rubber component ensures that the rubber phase component has higher impact resistance, and in addition, the proper molecular weight distribution also ensures that the polymer has good processability. That is, the invention obtains the basic PP-R resin with excellent performance by setting the propylene random copolymerization stage to prepare the continuous phase and selecting the proper reaction parameters and reaction conditions of the preparation steps of the continuous phase and the rubber dispersed phase to regulate and control the performance of the generated continuous phase and the rubber dispersed phase and the combination relationship thereof.

According to a specific embodiment of the process of the invention, the copolymerization in the first stage is a binary random copolymerization of ethylene/propylene or propylene/butene or a ternary random copolymerization of ethylene/propylene/butene; the copolymerization in the second stage is the same as or different from the copolymerization in the first stage, and is also a binary random copolymerization of ethylene/propylene or propylene/butene or a ternary random copolymerization of ethylene/propylene/butene.

According to the invention, in the preparation of the composition, the added second external electron donor can act with (if can react with) the catalytic activity center in the copolymerization product material in the first stage to generate a new catalytic activity center, and the polymerization of propylene, ethylene and/or butylene to a copolymerization polymer with a molecular weight very different from that of the product obtained in the first stage is continuously initiated in the second stage. The second external electron donor has higher hydrogen response than the first external electron donor, and can prepare a high melt index polymer in the presence of a small amount of hydrogen. It is then important to control the molecular weight of the resulting polymer by controlling the reaction conditions of the second polymerization step. At this time, the preparation of the rubber phase utilizes the second external electron donor with good hydrogen-adjusting sensitivity added in the second stage of the first step, and then the rubber phase molecular weight matched with the continuous phase is obtained under the specific hydrogen concentration, so that the base resin with good performance is obtained, which is one of the outstanding advantages of the invention. The composition and structure control of the rubber phase component ensures that the rubber phase component has high melt strength, the specific content of the rubber component ensures that the rubber phase component has higher impact resistance, and in addition, the proper molecular weight distribution also ensures that the polymer has good processability. That is, by setting a plurality of propylene random copolymerization stages to prepare the continuous phase and selecting appropriate reaction parameters and reaction conditions for the continuous phase and rubber dispersed phase preparation steps, the properties of the produced continuous phase and rubber dispersed phase and their combination relationship are regulated, and on this basis, a base resin having excellent properties is obtained. The base resin is then blended with flame retardants and conductive fillers, etc. to give the compositions herein.

In the method provided by the invention, the random copolymerization polypropylene is prepared as a continuous phase to provide certain rigidity and better heat sealability for the basic PPR resin, and then the propylene-ethylene copolymer is prepared as a rubber phase, namely a dispersed phase, so that the toughness of the basic resin can be improved; and finally, carrying out a blending process to prepare the composition. In particular, in the present invention, a foamed material having excellent properties can be prepared by arranging a random polypropylene continuous phase to include at least a first random copolymer polypropylene and a second random copolymer polypropylene, each of which is independently selected from a propylene/ethylene random copolymer, a propylene/butene random copolymer or an ethylene/propylene/butene terpolymer, so that the continuous phase and the dispersed phase are better compounded with each other to produce a base PP-R resin having high melt strength and high toughness, and then blended with a conductive filler, a flame retardant, and the like.

The first two steps provided by the present invention are preferably carried out in two or more reactors operated in series.

The process for the preparation of the basic PP-R resin according to the invention (first and second step) is a direct polymerization process with a Ziegler-Natta catalyst. The method comprises the steps of respectively using two or more different types of external electron donors in a plurality of reactors connected in series, selecting proper dosage of the external electron donors, combining different dosage of chain transfer agent hydrogen, reaction monomer composition and the like in the reaction, and preparing a continuous phase of the random copolymer with specific melt index and wide molecular weight distribution containing a large amount of ultrahigh molecular weight components, wherein the molecular weight distribution M of the continuous phase component of the random copolymer is_w/M_n(weight average molecular weight/number average molecular weight) 6 to 20; m_z+1/M_n(Z +1 average molecular weight/number average molecular weight) is greater than or equal to 70 and less than 150. The content of the random copolymerization polypropylene continuous phase component with the molecular weight of more than 500 ten thousand fractions is more than or equal to 1.5 weight percent and less than or equal to 5 weight percent; the content of the fraction having a molecular weight of less than 5 ten thousand is not less than 15.0% by weight and not more than 40% by weight. And further carrying out copolymerization of propylene and ethylene on the basis to prepare a rubber phase dispersed in the continuous phase, and controlling the composition, structure, content and the like of the rubber phase by controlling the reaction conditions of copolymerization reaction to obtain the basic PP-R resin with high melt strength effect.

In the process provided by the present invention, the catalyst used is a Ziegler-Natta catalyst, preferably a catalyst with high stereoselectivity. The Ziegler-Natta catalyst having high stereoselectivity as used herein means a catalyst which can be used for the preparation of a propylene homopolymer having an isotactic index of more than 95%. Such catalysts generally comprise (1) a titanium-containing solid catalyst active component, the main components of which are magnesium, titanium, halogen and an internal electron donor; (2) an organoaluminum compound co-catalyst component; (3) an external electron donor component.

The solid catalyst active component (which may also be referred to as a procatalyst) of the Ziegler-Natta catalyst used in the process of the present invention may be well known in the art. Specific examples of such active solid catalyst component (1) containing that can be used are, for example, described in patent documents CN85100997, CN98126383.6, CN98111780.5, CN98126385.2, CN93102795.0, CN00109216.2, CN99125566.6, CN99125567.4 and CN 02100900.7. These patent documents are incorporated by reference herein in their entirety.

The organoaluminum compound in the Ziegler-Natta catalyst used in the process of the present invention is preferably an alkylaluminum compound, more preferably a trialkylaluminum, for example, at least one of triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, trihexylaluminum and the like.

The molar ratio of the titanium-containing active solid catalyst component and the organoaluminum compound in the Ziegler-Natta catalyst used in the process of the present invention is 10:1 to 500:1, preferably 25:1 to 100:1, in terms of aluminum/titanium.

According to a particular embodiment of the process according to the invention, the first external electron donor is selected from those of formula R¹R²Si(OR³)₂At least one of the compounds of (a); wherein R is²And R¹Each independently selected from C₁-C₆Straight or branched alkyl, C₃-C₈Cycloalkyl and C₅-C₁₂Heteroaryl of (A), R³Is C₁-C₃A straight chain aliphatic group. Specific examples include, but are not limited to, methyl-cyclopentyl-dimethoxysilane, ethyl-cyclopentyl-dimethoxysilane, n-propyl-cyclopentyl-dimethoxysilane, bis (2-methylbutyl) -dimethylOxysilane, bis (3-methylbutyl) -dimethoxysilane, 2-methylbutyl-3-methylbutyl-dimethoxysilane, bis (2, 2-dimethyl-propyl) -dimethoxysilane, 2-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane, 3-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane-dimethyldimethoxysilane, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, methyl-isopropyldimethoxysilane, isopropyl-cyclopentyldimethoxysilane, dicyclopentyldimethoxysilane, di-n-ethyldimethoxysilane, di, At least one of isopropyl-isobutyldimethoxysilane and diisopropyldimethoxysilane.

According to another embodiment of the present invention, the molar ratio of the organoaluminum compound to the first external electron donor is 1:1 to 100:1, preferably 10:1 to 60:1, in terms of aluminum/silicon.

In the process according to the invention, the catalyst comprising the first external electron donor may be fed directly to the first random copolymerization reactor or may be fed to the first random copolymerization reactor after pre-contacting and/or pre-polymerization as known in the art. The prepolymerization refers to that the catalyst is prepolymerized at a certain ratio at a lower temperature to obtain the ideal particle shape and dynamic behavior control. The prepolymerization can be liquid phase bulk continuous prepolymerization, and can also be batch prepolymerization in the presence of an inert solvent. The temperature of the prepolymerization is usually-10 to 50 ℃ and preferably 5 to 30 ℃. A precontacting step may optionally be provided before the prepolymerization process. The pre-contact step refers to the complex reaction of a cocatalyst, an external electron donor and a main catalyst (solid active center component) in the catalyst system to obtain the catalyst system with polymerization activity. The temperature of the precontacting step is usually controlled to be-10 to 50 ℃, preferably 5 to 30 ℃.

In a particular embodiment according to the invention, the amount of hydrogen used in the first stage may be, for example, 0-200 ppm. The obtained first random copolymerized polypropylene has a melt index of 0.001-0.4g/10min as measured at 230 ℃ under a load of 2.16 kg. Wherein, in a specific example, the Ziegler-Natta catalyst comprising the first external electron donor is added continuously.

According to another embodiment of the present invention, the second external electron donor is at least one selected from the group consisting of compounds represented by the general chemical formulas (I), (II), and (III);

wherein R is₁And R₂Each independently selected from C₁-C₂₀One of linear, branched or cyclic aliphatic radicals, R₃、R₄、R₅、R₆、R₇And R₈Each independently selected from a hydrogen atom, a halogen atom, C₁-C₂₀Straight or branched alkyl of (2), C₃-C₂₀Cycloalkyl radical, C₆-C₂₀Aryl radical, C₇-C₂₀Alkylaryl and C₇-C₂₀One of aralkyl groups; r₉、R₁₀And R₁₁Each independently is C₁-C₃Straight-chain aliphatic radical, R₁₂Is C₁-C₆Straight or branched alkyl or C₃-C₈A cycloalkyl group. The second external electron donor includes, but is not limited to, 2-diisobutyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2-benzyl-1, 3-dimethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 2-bis (cyclohexylmethyl) -1, 3-dimethoxypropane, 2-isopropyl-2-3, 7-dimethyloctyl-dimethoxypropane, 2-isopropyl-1, 3-dimethoxypropane, 2-isopropyl-2-cyclohexylmethyl-1, 3-dimethoxypropane, 2-diisobutyl-1, 3-diethoxypropane, 2-diisobutyl-1, 3-dipropoxypropane, 2-isopropyl-2-isoamyl-1, 3-diethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dipropoxypropane, 2-bis (cyclohexylmethyl) -1, 3-diethoxypropane, n-propyltriethoxysilane, i-butyltriethoxysilane, i-butyltrimethoxysilane, i-butyltripropoxysilane, i-butyltributoxysilane, t-butyltriethoxysilaneAt least one of silane, t-butyl tripropoxysilane, t-butyl tributoxysilane, cyclohexyl triethoxysilane, cyclohexyl tripropoxysilane, tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

According to another embodiment of the present invention, the molar ratio of the organoaluminum compound to the second external electron donor is 1:1 to 60:1, preferably 5:1 to 30:1, calculated as aluminum/silicon or aluminum/oxygen.

According to some embodiments of the present invention, the molar ratio of the second external electron donor to the first external electron donor is between 1 and 30, preferably between 5 and 30, which is advantageous for obtaining a material with better properties

According to an embodiment of the present invention, the amount of hydrogen used in the second stage may be 2000-20000 ppm. The second random copolymer polypropylene has a higher melt index than the first random copolymer polypropylene. The second random copolymer polypropylene has a melt index of 0.1 to 15g/10min as measured at 230 ℃ under a load of 2.16 kg.

In both stages of the first step, the ethylene is added in an amount of from 0 to 100000ppm, preferably 100 and 50000 ppm; and/or the butene is added in an amount of 0 to 20 mol%, preferably 1 to 15 mol%.

In the process of the present invention, it is preferred that the second external electron donor is brought into sufficient contact with the catalyst component in the first-stage reaction product before the second-stage random copolymerization reaction. In some preferred embodiments, the second external electron donor may be added in the feed line after the first stage reactor and before the second stage reactor, or at the front end of the feed line of the second stage reactor, in order to first perform a precontacting reaction with the catalyst in the reaction product of the first stage before the second stage reaction.

According to the invention, the ethylene content in the random polypropylene continuous phase is from 0 to 6% by weight, such as from 0.1 to 6% by weight. The butene content of the random polypropylene continuous phase is 0 to 10 wt%, such as 0.1 to 10 wt%.

Through the reaction of the first stage and the second stage, the random copolymerization polypropylene continuous phase is obtained, and has one or more of the following characteristics: molecular weight distribution Mw/Mn is 6-20; mz +1/Mn is greater than or equal to 70 and less than 150; the fraction having a molecular weight of more than 500 ten thousand is present in an amount of more than or equal to 1.5% by weight and less than or equal to 5% by weight; the content of the fraction having a molecular weight of less than 5 ten thousand is not less than 15.0% by weight and not more than 40% by weight. Wherein, the molecular weight of more than 500 ten thousand and less than 5 ten thousand refer to the part with molecular weight more than 500 ten thousand and the part with molecular weight less than 5 ten thousand in the molecular weight distribution curve, and this has been disclosed in the prior art, and will not be described again here.

According to the invention, the polymerization reaction of the first stage can be carried out in liquid-liquid phase, or in gas-gas phase, or using a combined liquid-gas technique. When liquid phase polymerization is carried out, the polymerization temperature is 0-150 ℃, preferably 60-100 ℃; the polymerization pressure should be higher than the saturation vapor pressure of propylene at the corresponding polymerization temperature. The polymerization temperature in the gas phase polymerization is 0 to 150 ℃, preferably 60 to 100 ℃; the polymerization pressure may be normal pressure or higher, and preferably 1.0 to 3.0MPa (gauge pressure, the same applies hereinafter). According to a preferred embodiment of the invention, the reaction temperature in the first stage is between 50 and 100 ℃, preferably between 60 and 85 ℃; the reaction temperature in the second stage is 55-100 deg.C, preferably 60-85 deg.C. The yields of the first random copolymer polypropylene and the second random copolymer polypropylene are 40:60 to 60: 40.

In the second stage, it is understood that the random copolymer polypropylene continuous phase stream contains unreacted catalyst from the first stage, which continues to catalyze the polymerization in the second stage. According to the present invention, it is preferred that the ratio of the melt index of the random copolymerized polypropylene continuous phase obtained through the first step to the melt index of the base PP-R resin comprising the random copolymerized polypropylene continuous phase and the propylene-ethylene copolymer rubber dispersed phase obtained through the second step is 0.6 or more and less than 1. It is also preferred that the weight ratio of the dispersed phase of propylene-ethylene copolymer rubber to the continuous phase of random polypropylene is from 11 to 80: 100. By arranging the continuous phase of random copolymer polypropylene of the base PP-R resin of the invention to comprise a combination of at least two random copolymers having different melt indices and having a specific ratio relationship, the base resin constituting the invention has a specific continuous phase, and with further combination of the continuous phase and the rubber phase, a composition having both high melt strength and good stiffness and toughness is produced.

In a preferred embodiment, in the second step, the amount of ethylene is from 20 to 60% of the total volume of ethylene and propylene. Preferably, in the second step, the volume ratio of hydrogen to the total amount of ethylene and propylene is from 0.02:1 to 1: 1. In the present invention, in order to obtain a base resin having high melt strength and at the same time high rigidity and toughness, it is important to control the composition, structure or properties of the dispersed phase and the continuous phase. The present invention, through these preferred conditions, makes it possible to prepare a composition having a molecular weight distribution, an ethylene content of the rubber phase, which is advantageous for achieving the objects of the present invention, thereby obtaining a base resin having better properties, and thus obtaining better properties.

The polymerization reaction of the second step is carried out in the gas phase. The gas phase reactor may be a gas phase fluidized bed, a gas phase moving bed, or a gas phase stirred bed reactor. The polymerization temperature is preferably 0 to 150 ℃ and more preferably 60 to 100 ℃. The polymerization pressure is any pressure below the partial pressure of the propylene at which it liquefies. Preferably, the reaction temperature in the second step is from 55 to 100 deg.C, preferably from 60 to 85 deg.C.

According to the process of the present invention, the polymerization reaction may be carried out continuously or batchwise.

M of Room temperature trichlorobenzene solubles in the base PP-R resin obtained in the second step according to the process of the invention_wM with trichlorobenzene insolubles at room temperature_wThe ratio is greater than 0.4 and less than 1; and/or the ethylene content in the room temperature xylene solubles is less than 50 wt%, more than 28 wt%. The base PP-R resin has a room temperature xylene solubles content of greater than 10 wt% and less than 35 wt%.

In the present invention, the room temperature xylene soluble content is determined according to the CRYSTEX method. For ease of characterization, the molecular weight of the rubber phase is based on the molecular weight of the room temperature trichlorobenzene solubles.

According to the process of the present invention, the base PP-R resin obtained in the second step has a melt index, measured at 230 ℃ under a load of 2.16kg, of 0.1 to 15g/10min, preferably of 0.1 to 6g/10 min. The basic PP-RMolecular weight distribution M of the resin_w/M_nLess than or equal to 10 and greater than or equal to 4; m_z+1/M_wGreater than 10 and less than 20. The ethylene content in the base PP-R resin is 8-20 wt%.

The contents of the base PP-R resin and its preparation, application No. CN2014106023083, described above, are hereby incorporated by reference in their entirety.

According to the present invention, the blend in the third step can be prepared according to various methods known in the art. In a specific embodiment, the blending is melt blending, preferably at a blending temperature of 170-. In the third step, lubricants and/or other auxiliaries may optionally also be added.

For example, the basic PP-R resin, the flame retardant, the conductive filler, and optionally the lubricant and other additives are directly mechanically mixed in a mechanical mixing device according to the mixture ratio, and then added into a melt blending device to be subjected to melt blending granulation at 170-200 ℃. Or a small amount of basic PP-R resin is respectively concentrated and blended with a flame retardant or a conductive filler to prepare flame-retardant master batches and antistatic master batches at 170-210 ℃, and then the two master batches and the basic PP-R resin are mixed in proportion and granulated at 170-200 ℃. The mechanical mixing device may be, for example, a high-speed stirrer, a kneader, or the like. The melt blending equipment may be, for example, a twin screw extruder, a single screw extruder, an open mill, an internal mixer, or the like.

Wherein the lubricant, conductive filler and flame retardant are as defined above.

According to another aspect of the invention, the invention also provides a flame-retardant antistatic random copolymerization polypropylene pipe which is prepared by using the composition or the composition prepared by the method as a raw material. The pipe has smooth appearance and inner wall, uniform wall thickness and no shrinkage phenomenon, and the flame retardant property, the antistatic property and the impact resistance of the pipe all meet the requirements of underground coal mines on the application of plastic pipes. And the preparation method is simple and effective and is easy to operate. Meanwhile, when the antistatic agent of the carbon material series is used, the antistatic agent can generate a synergistic effect with the flame retardant, and is beneficial to generating a compact carbon layer for blocking flame and materials, so that the addition amount of the flame retardant can be reduced; not only can reduce the production cost of the pipe, but also can reduce the reduction of the impact property of the pipe.

According to the invention, when the polypropylene composition obtained by matching the basic PP-R resin, the flame retardant and the conductive filler is used for manufacturing the pipe by adopting a general double-screw pipe extrusion process, the polypropylene composition has the advantages of high extrusion rate and low screw torque, is suitable for the economic requirement of the existing modified PP-R pipe extrusion process, and the obtained modified PP-R pipe also has excellent flame retardant property, antistatic property and impact resistance, is suitable for the requirement of underground coal mine pipelines, and has great industrial application prospect.

According to another aspect of the present invention, there is also provided a method for preparing a flame retardant antistatic random copolymer polypropylene pipe, comprising:

s1, mixing the composition with an auxiliary agent, or preparing a flame-retardant antistatic random copolymer polypropylene composition by the method and then mixing the flame-retardant antistatic random copolymer polypropylene composition with the auxiliary agent;

s2, carrying out extrusion molding on the mixed material to obtain the pipe.

The auxiliary agents comprise an antioxidant, a slipping agent, an anti-sticking agent and the like, and cannot adversely affect the extrusion performance, the flame retardant performance, the antistatic performance and the mechanical performance.

According to the method of the invention, the temperature of the extrusion molding is 170-200 ℃. The mixing time is 2-5 min.

In a particular embodiment, the method comprises:

s1, stirring a mixture of the high-performance (halogen-free) flame-retardant antistatic PP-R composition and an auxiliary agent such as an antioxidant for 2-5min in a mixer;

s2, extruding and molding the mixture at 170-200 ℃ to obtain the PP-R pipe with excellent flame-retardant, antistatic and impact-resistant properties.

The halogen-free flame-retardant antistatic high-performance PP-R pipe provided by the invention still has excellent high and low temperature impact resistance although being subjected to flame-retardant antistatic modification, and the composition still has higher melt strength, so that on one hand, in the pipe extrusion processing process, the torque during extrusion can be effectively reduced, and the extrusion traction speed is increased; on one hand, the prepared pipe has smooth appearance and inner wall, uniform wall thickness and no shrinkage phenomenon. The flame retardant property, the antistatic property and the impact resistance of the (halogen-free) flame retardant antistatic high-performance PP-R pipe provided by the invention all meet the requirements of underground coal mines on the application of plastic pipes. And the preparation method is simple and effective and is easy to operate. When the antistatic agent of carbon material series is used in the invention, the antistatic agent can generate synergistic effect with the flame retardant, and is helpful for generating a compact carbon layer for blocking flame and materials, so that the addition amount of the flame retardant can be reduced. Not only can reduce the production cost of the pipe, but also can reduce the reduction of the impact property of the pipe.

Detailed Description

The invention will be further described with reference to the following examples, but it should be noted that: the present invention is by no means limited to these examples.

The following raw materials and the instruments and equipment used in the examples and comparative examples include:

ethylene propylene random copolymerization PPR pipe material: the physical properties of the product of Beijing Yanshan division, petrochemical, China, having a melt flow rate/(g/10 min) of 0.25, are shown in Table 2, in comparison with those of preparation examples 1 and 2.

All other raw materials are commercially available.

The test equipment and the test method comprise the following steps:

the polymer related data in the examples were obtained according to the following test methods:

(1) the content of xylene soluble substances at room temperature and the content of ethylene in xylene soluble substances at room temperature (namely the content of a characteristic rubber phase and the content of ethylene in the rubber phase) are measured by a CRYSTEX method, a series of samples with different contents of xylene soluble substances at room temperature are selected as standard samples to be corrected by a CRYST-EX instrument (IR 4+ detector) produced by Spanish Polymer Char company, and the content of the xylene soluble substances at room temperature of the standard samples is measured by ASTM D5492. The infrared detector carried by the instrument can detect the weight content of the propylene in the soluble substance and is used for representing the ethylene content (ethylene content in a rubber phase) in the xylene soluble substance at room temperature, namely 100 percent to the weight content of the propylene.

(2) The tensile strength of the resin is measured according to the GB/T1040.2 method;

(3) melt mass flow rate MFR (also called melt index): measured according to ASTM D1238 using a melt index apparatus model 7026 from CEAST, at 230 ℃ under a load of 2.16 kg;

(4) flexural modulus: measured according to the method described in GB/T9341;

(5) impact strength of the simply supported beam notch: measured according to the method described in GB/T1043.1;

(6) ethylene content: measured by infrared spectroscopy (IR), wherein the standard is calibrated by NMR. The NMR method was carried out using an AVANCE III 400MHz NMR spectrometer (NMR), 10 mm probe, from Bruker, Switzerland. The solvent is deuterated o-dichlorobenzene, about 250mg of the sample is placed in 2.5ml of deuterated solvent, and the sample is dissolved by heating in an oil bath at 140 ℃ to form a uniform solution. And (3) acquiring 13C-NMR (nuclear magnetic resonance), wherein the probe temperature is 125 ℃, 90-degree pulses are adopted, the sampling time AQ is 5 seconds, the delay time D1 is 10 seconds, and the scanning times are more than 5000 times. Other manipulations, spectral peak identification, etc. were performed as required for commonly used NMR experiments.

(7) Molecular weight Polydispersity Index (PI): the resin sample is molded into a 2mm slice at 200 ℃, dynamic frequency scanning is carried out on the sample at 190 ℃ under the protection of nitrogen by adopting an ARES (advanced rheometer extended system) rheometer of Rheometric Scientific Inc in America, a parallel plate clamp is selected, appropriate strain amplitude is determined to ensure that the experiment is carried out in a linear region, and the change of storage modulus (G '), energy consumption modulus (G') and the like of the sample along with the frequency is measured. The molecular weight polydispersity index PI is 105/Gc, where Gc (unit: Pa) is the modulus value at the intersection of the G' -frequency curve and the G "-frequency curve.

(8) Melt strength was measured using a Rheotens melt strength meter manufactured by Geottfert Werkstoff pruefmamschinen, germany. After the polymer is melted and plasticized by a single screw extruder, a melt bar is extruded downwards by a 90-degree steering head provided with an 30/2 length-diameter-ratio die, the bar is clamped between a group of two rollers which rotate oppositely at constant acceleration to carry out uniaxial stretching, the force in the melt stretching process is measured and recorded by a force measuring unit connected with the stretching rollers, and the maximum force value measured when the melt is stretched until the melt is broken is defined as the melt strength.

(9) Molecular weight (Mw, Mn) and molecular weight distribution (Mw/Mn, Mz + 1/Mw): the molecular weight and molecular weight distribution of the sample were measured by PL-GPC 220 gel permeation chromatograph manufactured by Polymer laboratories, UK, or GPCIR apparatus manufactured by Polymer Char, Spanish (IR5 concentration Detector), the column was 3 PLgel 13umOlexis columns in series, the solvent and mobile phase were 1,2, 4-trichlorobenzene (containing 250ppm of antioxidant 2, 6-dibutyl-p-cresol), the column temperature was 150 ℃, the flow rate was 1.0ml/min, and the calibration was carried out universally by EasiCal PS-1 narrow distribution polystyrene standard manufactured by PL. The preparation process of the room temperature trichlorobenzene soluble substance comprises the following steps: accurately weighing a sample and a trichlorobenzene solvent, dissolving for 5 hours at 150 ℃, standing for 15 hours at 25 ℃, and filtering by adopting quantitative glass fiber filter paper to obtain a solution of trichlorobenzene soluble matters at room temperature for determination. The content of trichlorobenzene soluble matter at room temperature was determined by correcting the GPC curve area with polypropylene of known concentration, and the molecular weight data of trichlorobenzene insoluble matter at room temperature was calculated from the GPC data of the original sample and the GPC data of the soluble matter.

(10) Herein, regarding the data of the random copolymerized polypropylene composition, the impact strength of the simple beam notch: measured according to the method described in GB/T1043.1; the surface resistivity is measured according to the method specified in GB/T1410-2006; the oxygen index is measured according to the method specified in GB/T2406.1-2008.

(11) The properties of the pipes prepared in the examples and the comparative examples were measured according to the method of MT181-88 "Standard for safety Performance test for underground Plastic pipes for coal mines".

Preparation of the high melt strength impact resistant base PP-R resin:

preparation example 1

This preparation example is intended to illustrate the base PP-R resin having high melt strength impact resistance and the method for preparing the same according to the present invention.

The propylene polymerization reaction is carried out on a polypropylene device, and the main equipment of the device comprises a prepolymerization reactor, a first loop reactor, a second loop reactor and a third gas-phase reactor. The polymerization method and the steps are as follows.

(1) Prepolymerization reaction

The main catalyst (DQC-401 catalyst, supplied by Oda, Beijing, China petrochemical catalyst Co., Ltd.), the cocatalyst (triethylaluminum) and the first external electron donor (diisopropyldimethoxysilane, DIPMS) were precontacted at 6 ℃ for 20min, and then continuously added into a continuous stirred tank type prepolymerization reactor to perform a prepolymerization reactor. The Triethylaluminum (TEA) flow into the prepolymerization reactor was 6.33g/hr, the diisopropyldimethoxysilane flow was 0.3g/hr, the procatalyst flow was 0.6g/hr, and the TEA/DIPMS ratio was 50 (mol/mol). The prepolymerization is carried out in a propylene liquid phase bulk environment, the temperature is 15 ℃, the residence time is about 4min, and the prepolymerization multiple of the catalyst is about 80-120 times under the condition.

(2) The first step is as follows: random copolymerization of propylene and ethylene

The first stage is as follows: the prepolymerized catalyst continuously enters a first loop reactor to complete the random copolymerization reaction of propylene and a small amount of ethylene in the first loop reactor, wherein the ethylene addition amount of the first loop is 10000 ppm. The polymerization temperature of the two loop reactors is 70 ℃, and the reaction pressure is 4.0 MPa; and (3) adding no hydrogen into the feed of the first loop reactor, wherein the concentration of the hydrogen detected by an online chromatographic method is less than 10ppm, so as to obtain the first random copolymerization polypropylene A.

And a second stage: 0.63g/hr of 2, 2-diisobutyl-1, 3-Dimethoxypropane (DIBMP) was added to the second loop reactor connected in series with the first loop reactor and mixed with the reactant stream from the first loop reactor, the TEA/DIBMP ratio was 5(mol/mol), where DIBMP was the second external electron donor. The polymerization temperature of the second loop reactor is 70 ℃, and the reaction pressure is 4.0 MPa; and adding a certain amount of hydrogen along with the propylene feeding, detecting the hydrogen concentration in the feeding to be 2000ppm by using an online chromatographic method, and generating a second random copolymer polypropylene B in the second loop reactor to obtain a random copolymer polypropylene continuous phase containing the first random copolymer polypropylene and the second random copolymer polypropylene.

(3) The second step is that: copolymerization of ethylene-propylene

Adding into a third reactorMeasuring hydrogen, H₂/(C₂+C₃)＝0.06(mol/mol)，C₂/(C₂+C₃)＝0.4(mol/mol)(C₂And C₃Respectively referring to ethylene and propylene), and continuously initiating ethylene/propylene copolymerization reaction in a third reactor, wherein the reaction temperature is 75 ℃, and a propylene-ethylene copolymer rubber disperse phase C is generated.

The final product contains the first random copolymerization polypropylene, the second random copolymerization polypropylene and the propylene-ethylene copolymer rubber disperse phase, and the polymer powder is obtained by removing the activity of the unreacted catalyst by wet nitrogen and heating and drying. The powder obtained by polymerization was added with 0.1 wt% of IRGAFOS 168 additive, 0.1 wt% of IRGANOX 1010 additive and 0.05 wt% of calcium stearate, and pelletized with a twin-screw extruder. The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 2 and 3.

Preparation example 2

The catalyst, the pre-complexing and the polymerization process conditions, the formula of the auxiliary agent and the addition amount are the same as those in preparation example 1. The difference from preparation example 1 is that: the comonomer ethylene addition in the first and second stages of the first step was changed to 30000 ppm. The analysis results of the obtained polymer and the physical properties of the polymer are shown in tables 1 and 2.

As can be seen from the results shown in tables 1 and 2, the base random copolymer polypropylene resin prepared according to the method of the present invention has high melt strength, and simultaneously has high notched impact strength at both room temperature and low temperature.

Example 1

This example illustrates the polypropylene composition and flame retardant antistatic PP-R pipe provided by the present invention.

The polypropylene composition provided by this example contains preparation example 1, a halogen-free flame retardant, a conductive filler and a lubricant.

The halogen-free flame retardant is superfine aluminum hydroxide prepared by a precipitation method, is produced by Jinan Texing company, and has the particle size of 500-800 nm.

The conductive filler is acetylene black which is purchased from Tianjin Lihua evolution chemical company, Ltd;

the lubricant is PEG lubricant produced by Switzerland, and has a weight average molecular weight of 10000.

(1) Preparation of polypropylene composition:

the components are weighed and mixed according to the proportion, wherein the preparation example 1 is 100kg, the halogen-free flame retardant is 40kg, the conductive filler is 3kg, and the adding amount of the lubricant is 0.1 kg. Then adding the mixture into a high-speed stirrer for uniform mixing, and adding the mixed material into W&In a feeder of a double-screw extruder manufactured by the company P, materials enter the double screws through the feeder, the temperature of the screws is kept between 170 ℃ and 200 ℃ in the processing process, and the materials are melted and mixed uniformly through the screws, extruded, granulated and dried to obtain the flame-retardant antistatic PP-R composition granules. The notched Izod impact of the material at 23 ℃ was 25.8KJ/m²Oxygen index of 28.9 and surface resistance of 5 x 10⁶Ω。

(2) Preparing a flame-retardant antistatic PP-R pipe:

drying the polypropylene composition granules prepared in the step (1), then extruding the obtained granules into a pipe under the conditions that the melting section temperature of an extruder is 220 ℃, the die section temperature is 205 ℃, and cooling and sizing the extruded pipe blank under the traction of a traction machine to obtain the pipe with the outer diameter of 32mm and the wall thickness of 3 mm. The head pressure was 13MPa, and after setting the appropriate screw speed, the torque was 52.0%. The drawing speed is 12 m/min. The flame-retardant antistatic PP-R pipe material is subjected to basic performance test, and the result is shown in Table 3.

Example 2

The halogen-free flame retardant is APP, produced by Thai, Inc. of Jinan.

The conductive filler is graphene, and is purchased from Xiamen graphene technology Limited of Xiamen;

(1) Preparation of polypropylene composition:

a polypropylene pipe was produced by following the procedure of example 1, except that the polypropylene obtained in production example 1 was replaced with the same parts by weight of the polypropylene obtained in production example 2, to obtain pellets of a flame-retardant antistatic PP-R composition. The notched Izod impact of the material at 23 ℃ was 29.4KJ/m²Oxygen index of 35.3, surface resistance 2 x 10⁶Ω。

(2) Preparing a flame-retardant antistatic PP-R pipe:

drying the polypropylene composition granules prepared in the step (1), then extruding the obtained granules into a pipe under the conditions that the melting section temperature of an extruder is 220 ℃, the die section temperature is 205 ℃, and cooling and sizing the extruded pipe blank under the traction of a traction machine to obtain the pipe with the outer diameter of 32mm and the wall thickness of 3 mm. The head pressure was 11.5MPa, and after setting the appropriate screw speed, the torque was 55.6%. The drawing speed was 14 m/min. The flame-retardant antistatic PP-R pipe material is subjected to basic performance test, and the result is shown in Table 3.

Example 3

The halogen-free flame retardant is an intumescent flame retardant JLS220D which is produced by Hangzhou Jielsen company;

the conductive filler is multi-walled carbon nanotubes (MWNTs) produced by Cheaptubes of America, the diameter is 20-30nm, and the length is 20-30 μm;

(1) Preparation of polypropylene composition:

weighing and mixing the components according to the proportion, wherein 25kg of the preparation example 1 and 25kg of the halogen-free flame retardant are taken, adding the mixture into a high-speed stirrer for uniform mixing, and then adding the mixed material into W&In a feeder of a double-screw extruder manufactured by company P, materials enter the double screws through the feeder, the temperature of the screws is kept between 170 ℃ and 200 ℃ in the processing process, and the materials are melted and mixed uniformly by the screws, extruded, granulated and dried to obtain the polypropylene flame-retardant modified granulesA. Taking 25kg of preparation example 1, 0.75kg of conductive filler and 0.05kg of lubricant, adding the mixture into a high-speed stirrer, uniformly mixing, and adding the mixed material into W&In a feeder of a double-screw extruder manufactured by company P, materials enter the double screws through the feeder, the temperature of the screws is kept between 190 ℃ and 220 ℃ in the processing process, and the materials are melted and mixed uniformly by the screws, extruded, granulated and dried to obtain polypropylene antistatic modified granules B. Then 50kg of preparation example 1 is taken, mixed with A, B and 0.05kg of lubricant and added into a high-speed stirrer for uniform mixing, and the mixed material is added into W&In a feeder of a double-screw extruder manufactured by the company P, materials enter the double screws through the feeder, the temperature of the screws is kept between 170 ℃ and 200 ℃ in the processing process, and the materials are melted and mixed uniformly through the screws, extruded, granulated and dried to obtain the flame-retardant antistatic PP-R composition granules. The notched Izod impact of the material at 23 ℃ was 35.7KJ/m²Oxygen index of 36.4 and surface resistance of 9 x 10⁵Ω。

(2) Preparing a flame-retardant antistatic PP-R pipe:

drying the polypropylene composition granules prepared in the step (1), then extruding the obtained granules into a pipe under the conditions that the melting section temperature of an extruder is 220 ℃, the die section temperature is 205 ℃, and cooling and sizing the extruded pipe blank under the traction of a traction machine to obtain the pipe with the outer diameter of 32mm and the wall thickness of 3 mm. The head pressure was 11.5MPa, and after setting the appropriate screw speed, the torque was 51.4%. The traction speed is 15.5 m/min. The flame-retardant antistatic PP-R pipe material is subjected to basic performance test, and the result is shown in Table 3.

Example 4

Pellets of a flame-retardant antistatic PP-R composition and polypropylene pipes were prepared in the same manner as in example 3, except that the polypropylene obtained in preparation example 1 was replaced with the same parts by weight of the polypropylene obtained in preparation example 2 to obtain pellets of a flame-retardant antistatic PP-R composition. The notched Izod impact of the material at 23 ℃ was 39.2KJ/m²Oxygen index of 35.9 and surface resistance of 1 x 10⁶Ω。

The pipe with the outer diameter of 32mm and the wall thickness of 3mm is prepared. The head pressure was 12MPa, and the screw rotation speed and torque were 53.8% in accordance with example 1. The drawing speed is 15 m/min. The PP-R pipe basic performance test is carried out on the pipe, and the result is shown in Table 3.

Comparative example 1

Pellets of a flame retardant antistatic PP-R composition and polypropylene pipes were prepared in the same manner as in example 1, except that the polypropylene prepared in preparation example 1 was replaced with the same parts by weight of the ethylene-propylene random copolymer PP-R pipe material 4220 to obtain pellets of a flame retardant antistatic PP-R composition. The notched Izod impact of the material at 23 ℃ was 11.2KJ/m²Oxygen index of 23.9 and surface resistance of 2 x 10⁸Ω。

According to the method of example 1, no acceptable PP-R pipe could be extruded.

Comparative example 2

Pellets of a flame retardant antistatic PP-R composition and polypropylene pipes were prepared in the same manner as in example 2, except that the polypropylene prepared in preparation example 2 was replaced with the same parts by weight of the ethylene-propylene random copolymer PP-R pipe material 4220 to obtain pellets of a flame retardant antistatic PP-R composition. The notched Izod impact of the material at 23 ℃ was 15.3KJ/m²Oxygen index of 26.2 and surface resistance of 9 x 10⁷Ω。

According to the method of example 2, no acceptable PP-R pipe could be extruded.

Comparative example 3

Pellets of a flame retardant antistatic PP-R composition and polypropylene pipes were prepared in the same manner as in example 3, except that the polypropylene prepared in preparation example 1 was replaced with the same parts by weight of the ethylene-propylene random copolymer PP-R pipe material 4220 to obtain pellets of a flame retardant antistatic PP-R composition. The notched Izod impact of the material at 23 ℃ was 18.6KJ/m²Oxygen index of 31.3 and surface resistance of 7 x 10⁶Ω。

The pipe with the outer diameter of 32mm and the wall thickness of 3mm is prepared. The head pressure was 15MPa, and the screw rotation speed and torque were 61.0% in accordance with example 3. The drawing speed is 10 m/min. The PP-R pipe basic performance test is carried out on the pipe, and the result is shown in Table 3.

Comparative example 4

Flame retardant was prepared according to the method of example 4Antistatic PP-R composition pellets and polypropylene pipes, except that the polypropylene prepared in preparation example 2 was replaced with the same parts by weight of an ethylene-propylene random copolymer PP-R pipe material 4220, and β crystal nucleating agent TMB-5 (produced by Shanxi chemical research institute) was added in a weight ratio of 3 ‰ to obtain flame-retardant antistatic PP-R composition pellets, the notched Izod impact of which at 23 ℃ was 22.9KJ/m²Oxygen index of 30.8 and surface resistance of 8 x 10⁶Ω。

The pipe with the outer diameter of 32mm and the wall thickness of 3mm is prepared. The head pressure was 14MPa, and the screw rotation speed and torque were 57.5% in accordance with example 4. The drawing speed was 11 m/min. The PP-R pipe basic performance test is carried out on the pipe, and the result is shown in Table 3.

As can be seen from examples 1 to 4, the two brands of high melt strength and impact resistance random copolymerization polypropylene of preparation examples 1 and 2 are used as base resin, and flame retardant antistatic PP-R compositions with excellent performances, such as granular materials, can be prepared by flame retardant modification and antistatic modification. The high-impact flame-retardant antistatic PP-R pipe meeting the use requirements under coal mines can be prepared by adopting the general pipe extrusion process conditions. If a small amount of high melt strength impact PP-R is respectively concentrated and blended with a flame retardant or a conductive filler to prepare flame-retardant master batches and antistatic master batches, and then the two master batches and the high melt strength impact PPR are mixed in proportion to carry out granulation to obtain flame-retardant antistatic PP-R composition granules, compared with the flame-retardant antistatic PP-R composition granules which are obtained by directly mixing the high melt strength impact PP-R, the flame retardant, the conductive filler and the like in proportion and directly carrying out melt blending granulation, the prepared pipe has better properties.

As can be seen from comparative examples 1-2, the random copolymerization polypropylene pipe materials in the market, such as ethylene propylene random copolymerization polypropylene 4220 produced by petrochemical Yanshan mountain, in the preparation examples 1 and 2 have more excellent impact resistance and processability before and after flame retardant antistatic modification. 4220 after direct one-step simultaneous flame-retardant antistatic modification, due to the addition of a large amount of microparticles incompatible with collective resin, the mechanical properties and the processing properties are greatly reduced, and the flame-retardant antistatic PP-R pipe cannot be prepared.

As can be seen from the comparative example 3, 4220 also adopts the process method of preparing the flame-retardant antistatic PP-R composition granules by respectively preparing the flame-retardant master batch antistatic master batches and then blending and melting, so that the flame-retardant antistatic pipe can be prepared. But the appearance quality of the pipe has defects, and the use requirement of the underground plastic pipeline of the coal mine cannot be met.

It can be seen from comparative example 4 that 4220 added with the beta crystal nucleating agent TMB-5, although the produced pipe can pass the pipe performance test, the wall thickness is uniform, the inner wall and the outer wall are smoother, and the wavy stripes are not obvious. However, from the aspect of processing conditions, when the pipes are produced by using the preparation examples 1 and 2 under the same auxiliary agent formula, process flow and extrusion temperature, the traction speed can be set to be higher, the torque of a main machine can be lower, the energy consumption of production and the load of equipment are reduced, and the production efficiency is greatly improved. The prepared pipe with the same specification has smoother and smoother appearance and uniform wall thickness. Comparative example 4 still requires a slower traction speed setting and a higher main engine torque. Therefore, compared with the embodiments 3 to 4, the production efficiency is lower and the production cost is higher.

The situation shows that the flame-retardant antistatic PP-R composition provided by the invention can meet the requirements of special occasions such as underground coal mines and other special occasions with requirements on flame retardance and antistatic property when applied to the production of plastic pipes, can effectively improve the production efficiency of the pipes, reduce the energy consumption and equipment loss cost and reduce the use of processing aids, thereby obtaining remarkable economic benefits. The random copolymerization polypropylene pipe material used in the market at present needs to add expensive beta nucleating agent to reach the level of the high-performance PP-R pipe material mentioned in the invention.

Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, pressure, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.

It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.

Claims

1. A flame retardant, antistatic random copolymer polypropylene composition comprising a base random copolymer polypropylene resin, a flame retardant and an electrically conductive filler, wherein the base random copolymer polypropylene resin comprises a random copolymer polypropylene continuous phase and a propylene-ethylene copolymer rubber dispersed phase, wherein the random copolymer polypropylene continuous phase comprises at least a first random copolymer polypropylene and a second random copolymer polypropylene, each of the first random copolymer polypropylene and the second random copolymer polypropylene is independently selected from propylene/ethylene random copolymer, propylene/butylene random copolymer and ethylene/propylene/butylene terpolymer random copolymer;

the content of xylene solubles at room temperature in the base random copolymer polypropylene resin is more than 10% by weight and less than 35% by weight; the ratio of the Mw of the trichlorobenzene soluble matter at room temperature to the Mw of the trichlorobenzene insoluble matter at room temperature is more than 0.4 and less than 1; the molecular weight distribution Mw/Mn of the base random copolymerized polypropylene resin is 10 or less and 4 or more; mz +1/Mw is greater than 10 and less than 20; the melt index of the basic random copolymerization polypropylene resin is 0.1-15g/10min measured at 230 ℃ under the load of 2.16 kg; the weight ratio of the propylene/ethylene copolymer rubber dispersed phase to the random copolymerization polypropylene continuous phase is 11-80: 100.

2. the composition according to claim 1, wherein the weight of the conductive filler is 0.1 to 10 parts and the weight of the flame retardant is 10 to 50 parts, based on 100 parts by weight of the base random copolymer polypropylene resin.

3. The composition according to claim 2, wherein the weight of the conductive filler is 0.75 to 3 parts and the weight of the flame retardant is 25 to 40 parts, based on 100 parts by weight of the base random copolymer polypropylene resin.

4. The composition of claim 2, wherein the flame retardant is a halogen-free flame retardant.

5. The composition of claim 2, wherein the conductive material is a carbon material.

6. Composition according to any one of claims 1 to 5, characterized in that the ethylene content in the room temperature xylene solubles is greater than 28% by weight and less than 50% by weight; and/or the ethylene content in the base random copolymerized polypropylene resin is 8-20 wt%; and/or the base random copolymerized polypropylene resin has a molecular weight polydispersity index of 4 to 10.

7. The composition of any one of claims 1-5, wherein the ratio of the melt index of the random copolymerized polypropylene continuous phase to the melt index of the base random copolymerized polypropylene resin is greater than or equal to 0.6 and less than 1.

8. The composition of claim 7, wherein the base random copolymer polypropylene resin has a melt index of 0.1 to 6g/10min measured at 230 ℃ under a load of 2.16 kg.

9. The composition according to any one of claims 1 to 5, wherein the random copolymer polypropylene continuous phase has the following characteristics: molecular weight distribution Mw/Mn is 6-20; mz +1/Mn is greater than or equal to 70 and less than 150; and/or, in the random copolymerized polypropylene continuous phase, the melt index of the first random copolymerized polypropylene is smaller than the melt index of the second random copolymerized polypropylene.

10. The composition of claim 9, wherein the first random copolymer polypropylene has a melt index of 0.001 to 0.4g/10min, as measured at 230 ℃ under a load of 2.16 kg.

11. The composition of any of claims 1-5, wherein the random copolymer polypropylene continuous phase has an ethylene content of 0 to 6 wt%; and/or a butene content of 0 to 10% by weight.

12. The composition of claim 11, wherein the random copolymer polypropylene continuous phase has an ethylene content of 0.1 to 6 wt%; and/or a butene content of 0.1 to 10% by weight.

13. The composition according to any one of claims 1 to 5, wherein the weight ratio of the first random copolymer polypropylene and the second random copolymer polypropylene is 40:60 to 60: 40.

14. The composition according to any one of claims 1 to 5, further comprising a lubricant.

15. The composition of claim 14, wherein the lubricant is present in an amount of 0.05 to 5 parts by weight, based on 100 parts by weight of the base random copolymer polypropylene resin.

16. The composition of claim 14, wherein the lubricant is present in an amount of 0.1 to 0.5 parts by weight, based on 100 parts by weight of the base random copolymer polypropylene resin.

17. A method of preparing the composition of any one of claims 1-16, comprising the steps of:

and a second stage: adding a second external electron donor to react with the catalyst in the material flow in the first stage, and then copolymerizing propylene and ethylene and/or butylene in the presence of the first random copolymerization polypropylene and hydrogen to prepare second random copolymerization polypropylene so as to obtain a material flow of a random copolymerization polypropylene continuous phase containing the first random copolymerization polypropylene and the second random copolymerization polypropylene;

the second step is that: carrying out propylene-ethylene copolymerization reaction in the presence of the continuous phase flow of the random copolymerization polypropylene obtained in the first step and hydrogen to generate a propylene-ethylene copolymer rubber phase, so as to obtain a basic random copolymerization polypropylene resin containing the continuous phase and the rubber phase;

18. The method according to claim 17, wherein in the third step, a lubricant is further added; and/or the blending is melt blending.

19. The method as claimed in claim 18, wherein the blending temperature is 170-220 ℃.

20. The process of any one of claims 17 to 19, wherein the molar ratio of the second external electron donor to the first external electron donor is from 1:1 to 30: 1; and/or in the Ziegler-Natta catalyst, the molar ratio of the organoaluminum compound to the titanium-containing active catalyst component, calculated as aluminum/titanium, is from 10:1 to 500: 1; and/or the molar ratio of the organoaluminum compound to the first external electron donor in the Ziegler-Natta catalyst is 1:1 to 100:1 in terms of aluminum/silicon.

21. The method of claim 20, wherein the molar ratio of the second external electron donor to the first external electron donor is from 5:1 to 30: 1; and/or in the Ziegler-Natta catalyst, the molar ratio of the organoaluminum compound to the titanium-containing active catalyst component, calculated as aluminum/titanium, is from 25:1 to 100: 1; and/or the molar ratio of the organoaluminum compound to the first external electron donor in the Ziegler-Natta catalyst is 10:1 to 60:1 in terms of aluminum/silicon.

22. The method of any one of claims 17-19, wherein the first external electron donor is selected from the group consisting of those of the formula R¹R²Si(OR³)₂At least one of the compounds of (a); wherein R is²And R¹Each independently selected from C₁-C₆Straight or branched alkyl, C₃-C₈Cycloalkyl and C₅-C₁₂Heteroaryl of (A), R³Is C₁-C₃A straight chain aliphatic group.

23. The process of claim 22, wherein the first external electron donor is selected from the group consisting of methyl-cyclopentyl-dimethoxysilane, ethyl-cyclopentyl-dimethoxysilane, n-propyl-cyclopentyl-dimethoxysilane, bis (2-methylbutyl) -dimethoxysilane, bis (3-methylbutyl) -dimethoxysilane, 2-methylbutyl-3-methylbutyl-dimethoxysilane, bis (2, 2-dimethyl-propyl) -dimethoxysilane, 2-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane, 3-methylbutyl-2, 2-dimethyl-propyl-dimethoxysilane, dimethyldimethoxysilane, dimethyl, At least one of dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, methyl-isopropyldimethoxysilane, isopropyl-cyclopentyldimethoxysilane, dicyclopentyldimethoxysilane, isopropyl-isobutyldimethoxysilane, and diisopropyldimethoxysilane.

24. The method according to any one of claims 17 to 19, wherein the second external electron donor is selected from at least one of the compounds represented by the general chemical formulae (I), (II) and (III);

wherein R is₁And R₂Each independently selected from C₁-C₂₀One of linear, branched or cyclic aliphatic radicals, R₃、R₄、R₅、R₆、R₇And R₈Each independently selected from a hydrogen atom, a halogen atom, C₁-C₂₀Straight or branched alkyl of (2), C₃-C₂₀Cycloalkyl radical, C₆-C₂₀Aryl radical, C₇-C₂₀Alkylaryl and C₇-C₂₀One of aralkyl groups; r₉、R₁₀And R₁₁Each independently is C₁-C₃Straight-chain aliphatic radical, R₁₂Is C₁-C₆Straight or branched alkyl or C₃-C₈A cycloalkyl group.

25. The method of claim 24, wherein the second external electron donor is selected from the group consisting of 2, 2-diisobutyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2-benzyl-1, 3-dimethoxypropane, 2-isopropyl-2-isoamyl-1, 3-dimethoxypropane, 2-bis (cyclohexylmethyl) -1, 3-dimethoxypropane, 2-isopropyl-2-3, 7-dimethyloctyl-dimethoxypropane, 2-isopropyl-1, 3-dimethoxypropane, 2-isopropyl-2-cyclohexylmethyl-1, 3-dimethoxypropane, 2-isobutyl-1, 3-dimethoxypropane, 2-phenyl-1, 3-dimethoxypropane, 2-isopropyl-2-cyclohexylmethyl-1, 3-dimethoxypropane, 2-isopropyl-2-dimethyloctyl-dimethoxypropane, 2-isopropyl-2-, 2, 2-diisobutyl-1, 3-diethoxypropane, 2-diisobutyl-1, 3-dipropoxypropane, 2-isopropyl-2-isopentyl-1, 3-diethoxypropane, 2-isopropyl-2-isopentyl-1, 3-dipropoxypropane, 2-bis (cyclohexylmethyl) -1, 3-diethoxypropane, n-propyltriethoxysilane, isopropyltriethoxysilane, isobutyltriethoxysilane, isobutyltrimethoxysilane, isobutyltripropoxysilane, isobutyltributoxysilane, tert-butyltriethoxysilane, tert-butyltripropoxysilane, tert-butyltributoxysilane, cyclohexyltriethoxysilane, cyclohexyltripropoxysilane, isopropyltripropoxysilane, isopropyltriethoxysilane, isopropyltripropoxysilane, isopropyltrimethoxysilane, isopropyltripropoxysilane, isopropyltriethoxysilane, at least one of tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

26. The process according to any one of claims 17 to 19, wherein the reaction temperature of the first stage is 50 to 100 ℃; and/or the reaction temperature of the second stage is 55-100 ℃; and/or the reaction temperature of the second step is 55-100 ℃.

27. The method of claim 26, wherein the reaction temperature of the first stage is 60-85 ℃; and/or the reaction temperature of the second stage is 60-85 ℃; and/or the reaction temperature of the second step is 60-85 ℃.

28. The process according to any one of claims 17 to 19, wherein in the second step, ethylene represents 20 to 60% of the total volume of ethylene and propylene, and/or the ratio of hydrogen to the total volume of ethylene and propylene is 0.02:1 to 1: 1;

and/or, in the first step, the ethylene is added in an amount of 0 to 100000 ppm; and/or the addition amount of the butene is 0-20 mol%; the amount of hydrogen used in the second stage is 2000-; and/or the amount of hydrogen used in the first stage is from 0 to 200 ppm.

29. The process as claimed in claim 28, wherein the ethylene is added in the first step in an amount of 100-50000 ppm; and/or the addition amount of the butene is 1-15 mol%.

30. A flame retardant antistatic random copolymer polypropylene pipe, which is prepared by using the composition of any one of claims 1 to 16 or the composition prepared by the method of any one of claims 17 to 29 as a raw material.

31. A method for preparing flame retardant antistatic random copolymerization polypropylene pipe, comprising:

s1 blending the composition of any one of claims 1 to 16 with other auxiliary agents, or preparing the flame-retardant antistatic random copolymerization polypropylene composition by the method of any one of claims 17 to 29, and then mixing the flame-retardant antistatic random copolymerization polypropylene composition with the auxiliary agents;

s2, carrying out extrusion molding on the mixed material to obtain the pipe.

32. The method as claimed in claim 31, wherein the temperature of the extrusion molding is 170-200 ℃, and/or the time of the mixing is 2-5 min.