CN107325394B

CN107325394B - Polypropylene composition and high-performance flame-retardant antistatic polypropylene pipe

Info

Publication number: CN107325394B
Application number: CN201610279974.7A
Authority: CN
Inventors: 徐耀辉; 吕明福; 郭鹏; 毕福勇; 张师军; 邹浩; 邵静波; 杨庆泉; 吕芸; 白弈青
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: CN107325394A

Abstract

The invention relates to a flame-retardant antistatic polypropylene composition and a pipe prepared from the same. The composition includes a base polypropylene resin including a propylene homopolymer component and an ethylene-1-butene copolymer, wherein the propylene homopolymer component includes at least a first propylene homopolymer and a second propylene homopolymer; the ratio of the Mw of the room temperature trichlorobenzene solubles to the Mw of the room temperature trichlorobenzene insolubles in the base polypropylene resin is more than 0.5 and less than 1, preferably more than 0.5 and less than 0.8; a room temperature xylene solubles content of greater than 10% by weight and less than 30% by weight; the content of 1-butene is 5-20 wt%. The pipe provided by the invention has good antistatic and flame retardant properties, high melt strength and good impact resistance.

Description

Polypropylene composition and high-performance flame-retardant antistatic polypropylene 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-H 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-H has excellent hydrostatic resistance, good chemical corrosion resistance and higher thermal deformation temperature, so that the PP-H can be applied to the fields of high-temperature industrial blow-off pipes and the like.

However, plastic pipes are insulating materials and are very prone to generate static electricity. Suspended dust in an industrial production environment and the surface of the PP-H pipe are mutually rubbed and collided, positive and negative charges are redistributed between the suspended dust and the surface of the PP-H pipe, and the positive and negative charges are respectively accumulated on the surface of the PP-H pipe and the dust. When the static charge accumulates to some extent, a spark is discharged, which may cause a fire or a chemical explosion. Meanwhile, PP-H pipes also have the disadvantages of flammability, pressure resistance and low impact resistance. In order to safely and reliably apply the PP-H pipe material to special fields such as high-temperature industrial pollution discharge, the flame retardant, antistatic and mechanical properties of the PP-H pipe material must be improved. However, flame retardant and antistatic modification of PP-H requires the addition of large amounts of flame retardant and antistatic agent, respectively. The compatibility of the auxiliary agent with PP-H which is commonly seen in the market is not good, and stress concentration and crystallization defects are generated in the 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 property and the processability of PP-H are greatly reduced by the factors.

Unmodified PP-H pipe materials sold in the market at present are basically modified to improve the performance of the homopolymerized polypropylene, and for example, the impact strength of the PP-H pipe materials is improved by adding a beta crystal nucleating agent. Patent CN201310006946 mentions that a beta-crystal nucleating agent is used for modifying a homo-polypropylene tube material to synchronously improve the rigidity and toughness of the homo-polypropylene tube 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 prior art, the PP-H pipe material is produced by only widening molecular weight distribution and properly reducing the isotacticity of the polymer so as to meet the requirement of processing and forming. Methods for producing high-performance polypropylene pipe materials are proposed in patents US6433087, JP2002295741 and KR20040048053, but the use of ethylene-propylene copolymer polypropylene, polystyrene elastomer or ethylene/propylene/butylene terpolymer and homo-polypropylene blends to produce high-performance pipe materials undoubtedly also leads to an increase in production cost and instability in material properties due to raw material quality and modification operations.

In addition to impact properties, the melt strength of homopolypropylene also has a great influence on the pipe processing technology. The softening point of the general homo-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 is easy to break, 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 homo-polypropylene pipe materials 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-H pipe material has poor flame retardance and poor antistatic property when being used for preparing a PP-H 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 high-temperature industrial sewage pipes, and the like, and provides a novel flame-retardant antistatic polypropylene composition (PP-H composition) and a high-performance flame-retardant antistatic PP-H pipe prepared from the polypropylene composition.

One of the purposes of the invention is to provide a high-performance flame-retardant antistatic PP-H composition. The composition includes a base polypropylene resin (base PP-H resin), a flame retardant, and a conductive filler. After intensive research, the inventor of the invention finds that when the polypropylene composition obtained by matching the basic PP-H resin, the flame retardant and the conductive filler is used for manufacturing a pipe by adopting a general twin-screw pipe extrusion process, the polypropylene composition has the advantages of high extrusion rate and low screw torque, meets the economic requirement of the existing modified PP-H pipe extrusion process, and the obtained modified PP-H pipe also has excellent flame retardant property, antistatic property and hydrostatic resistance, is suitable for the requirement of a high-temperature industrial sewage discharge pipeline, and has great industrial application prospect. The polypropylene composition has both high melt strength and high strength performance, and has antistatic property and flame retardance. The invention also provides a preparation method of the composition containing the basic PP-H resin.

The basic PP-H resin provided by the invention has high melt strength and high-low temperature and high-strength performance, and comprises a propylene homopolymer component and an ethylene/1-butylene copolymer component. Wherein the propylene homopolymer component comprises at least a first propylene homopolymer and a second propylene homopolymer. The ratio of the Mw of the room-temperature trichlorobenzene soluble substance to the Mw of the room-temperature trichlorobenzene insoluble substance in the base polypropylene resin is more than 0.5 and less than 1; a room temperature xylene solubles content of greater than 10% by weight and less than 30% by weight; the content of 1-butene is 5-20 wt%.

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

The room temperature xylene solubles content of the base polypropylene resin according to the present invention is more than 10% by weight and less than 30% by weight; m of room temperature trichlorobenzene soluble substance_wM with trichlorobenzene insolubles at room temperature_wThe ratio of (A) to (B) is greater than 0.5 and less than 1, preferably greater than 0.5 and less than 0.8. The rigidity and toughness of the base polypropylene resin are further optimized, and the melt strength is high. In some preferred embodiments, the 1-butene of the base polypropylene resin of the present inventionThe content is 5-20 wt%.

The melt index of the base polypropylene resin of the present invention is preferably controlled in the range of 0.1 to 15g/10min, preferably 0.1 to 10g/10min, and further preferably 0.1 to 6.0g/10 min. The melt index was measured at 230 ℃ under a load of 2.16 kg. For a base polypropylene resin having a high melt strength, factors affecting the melt strength become complicated because it is a material of a multi-phase structure. The present inventors found that the molecular weight distribution M of the base polypropylene resin is such that the high melt strength of the product is ensured_w/M_nPreferably less than or equal to 10 and greater than or equal to 4, M_z+1/M_wGreater than 10 and less than 20, preferably greater than 10 and less than 15.

The base polypropylene resin according to the present invention has a molecular weight Polydispersity Index (PI) of 4 to 8, preferably 4.5 to 6.

According to the invention, the propylene homopolymer component has a molecular weight distribution Mw/Mn of from 6 to 20, preferably from 10 to 16; 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. In a specific example, the propylene homopolymer component has a melt index, measured at 230 ℃ under a load of 2.16kg, of from 0.1 to 15g/10 min. The melt index ratio of the propylene homopolymer component to the base polypropylene resin is from 0.6:1 to 1: 1. Therefore, the propylene homopolymer component having the above characteristics as a continuous phase is advantageous in obtaining a composition excellent in properties. 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 weight ratio of the first propylene homopolymer to the second propylene homopolymer is from 40:60 to 60: 40. The first propylene homopolymer has a melt index less than the melt index of the second propylene homopolymer. In a specific example, the first propylene homopolymer has a melt index, measured at 230 ℃ under a load of 2.16kg, of from 0.001 to 0.4g/10 min. Furthermore, the above characteristics are advantageous for obtaining a base polypropylene resin having a high melt strength, and further for obtaining a composition having excellent properties.

The invention adopts ethylene/1-butylene-random copolymer as the rubber component, and the inventor of the invention finds that the effect is better when the weight ratio of the ethylene/1-butylene copolymer component to the propylene homopolymer component in the basic polypropylene resin is 11-80: 100; further, when the 1-butene content in the ethylene/1-butene copolymer is made 20 to 45% by weight, a base polypropylene resin having better rigidity and toughness is obtained. The basic polypropylene resin has better rigidity-toughness balance.

According to the present invention, there is provided a base polypropylene resin prepared by performing a propylene homopolymerization reaction in the presence of a first propylene homopolymer to obtain a propylene homopolymer component comprising the first propylene homopolymer and a second propylene homopolymer, and then performing a copolymerization reaction of ethylene and 1-butene in the presence of the propylene homopolymer component to obtain a material comprising an ethylene-1-butene copolymer. It follows that the base polypropylene resin of the present invention is not a simple blend of a propylene homopolymer component and an ethylene/1-butene copolymer component, but is a unitary polypropylene material comprising a propylene homopolymer and an ethylene-1-butene copolymer obtained after further carrying out a specific ethylene/1-butene copolymerization reaction on the basis of a specific propylene homopolymer component.

The basic polypropylene resin also has better heat resistance, and the melting peak temperature T of the final polypropylene resin is measured by DSC_mGreater than or equal to 158 ℃.

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 to 50 parts, for example, 10 to 50 parts of the halogen-free flame retardant, based on 100 parts by weight of the base polypropylene resin; preferably 25 to 40 parts, such as 25 to 30 parts.

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 specific embodiment, the conductive filler is 0.1 to 10 parts, preferably 0.75 to 3 parts, such as 2 to 3 parts, 1 to 3 parts, based on 100 parts by weight of the base polypropylene 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 molecules with a weight average 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 contained 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 weight of the high melt strength impact resistant base PP-H 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-H composition, and comprises the following components by weight: the basic PP-H resin: 100 parts of conductive filler: 0.1-10 parts, preferably 0.75-3 parts, halogen-free flame retardant: 10-50 parts, preferably 25-40 parts, lubricant: 0.05 to 5 parts, preferably 0.1 to 0.5 part.

The high-performance flame-retardant antistatic PP-H composition (such as a halogen-free flame-retardant antistatic PP-H 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-H 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. Furthermore, the surface resistivity of the sample of the antistatic composition was 10⁴-10⁹Omega, preferably 10⁴-10⁷Ω。

According to the present invention, there is also provided a method for preparing the flame retardant antistatic composition as described above, comprising:

the first step is as follows: propylene homopolymerization comprising:

the first stage is as follows: carrying out propylene homopolymerization reaction in the presence or absence of hydrogen under the action of a Ziegler-Natta catalyst containing a first external electron donor to obtain a first propylene homopolymer;

and a second stage: adding a second external electron donor to perform a complex reaction with a catalyst in a reaction product generated in the first stage, and then performing a propylene homopolymerization reaction in the presence of a first propylene homopolymer and hydrogen to generate a second propylene homopolymer, so as to obtain a propylene homopolymer component containing the first propylene homopolymer and the second propylene homopolymer;

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: an ethylene/1-butene copolymerization reaction of performing an ethylene-1-butene gas phase copolymerization reaction in the presence of the propylene homopolymer component and hydrogen to produce an ethylene/1-butene copolymer component, resulting in a base polypropylene resin comprising the propylene homopolymer component and an ethylene-1-butene copolymer (ethylene/1-butene copolymer) component;

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

In the method provided by the invention, the propylene homopolymer component is prepared as a continuous phase to provide certain rigidity for the basic polypropylene resin, and then the ethylene/1-butene copolymer component is prepared as a rubber phase, namely a dispersed phase on the basis of the propylene homopolymer component, so that the toughness of the product can be improved.

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

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 chosen 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 of the first external electron donor include, but are not limited to: 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, dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, dimethylcyclohexyldimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldichlorodimethoxysilane, dimethyldichlorosilane, dimethyldichlorodimethoxysilane, dimethylcyclohexyldimethoxysilane, dimethyldichlorosilane, dimethyldichloro, At least one of methyl isobutyl dimethoxysilane, dicyclohexyldimethoxysilane, methyl-isopropyl dimethoxysilane, isopropyl-cyclopentyl dimethoxysilane, dicyclopentyl dimethoxysilane, isopropyl-isobutyl dimethoxysilane and diisopropyl dimethoxysilane.

Wherein the molar ratio of the organic aluminum compound to the first external electron donor is 1:1 to 100:1, preferably 10:1 to 60:1, calculated as aluminum/silicon.

In the process according to the invention, the catalyst comprising the first external electron donor may be added directly to the homopolymerization reactor or, after precontacting and/or prepolymerization as known in the art, may be added to the homopolymerization reactor. 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 in the precontacting step is usually controlled to be-10 to 50 ℃, preferably 5 to 30 ℃.

In a preferred embodiment, the amount of hydrogen used in the first stage may be, for example, 0 to 200 ppm. In the second stage, the amount of hydrogen used was 2000-. The first propylene homopolymer obtained had a melt index, measured at 230 ℃ under a load of 2.16kg, of 0.001 to 0.4g/10 min. In a specific example, the Ziegler-Natta catalyst comprising the first external electron donor is added continuously.

According to another embodiment of the method of the present invention, in the second stage, the second external electron donor is selected from at least one of the 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. Specific examples of the second external electron donor include, but are not limited to: 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-diisobutyl-1, 3-diethoxypropane, 2, 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, at least one of isobutyl tributoxysilane, tert-butyl triethoxysilane, tert-butyl tripropoxysilane, tert-butyl tributoxysilane, cyclohexyl triethoxysilane, cyclohexyl tripropoxysilane, tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

Wherein the molar ratio of the organic aluminum compound to the second external electron donor is 1:1 to 60:1 in terms of aluminum/silicon or aluminum/oxygen, and preferably 5:1 to 30: 1.

According to a preferred embodiment of the present invention, the molar ratio of the second external electron donor to the first external electron donor is from 1:1 to 30:1, preferably from 5:1 to 30: 1. Since the hydrogen response of the second external electron donor is higher than that of the first external electron donor, the melt index of the resulting second homopolymer is higher than that of the first homopolymer. Preferably, the weight ratio of the first propylene homopolymer to the second propylene homopolymer is from 60:40 to 60: 40.

In the process of the present invention, it is preferred that the second external electron donor is brought into intimate contact with the catalyst component in the first stage reaction product prior to the second stage homopolymerization. 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, by at least two stages of homopolymerization in the first step, external electron donor compounds with different hydrogen sensitivity are added in stages to obtain a propylene homopolymer component continuous phase with a specific melt index (0.1-less than 15g/10min) and a very wide molecular weight distribution, wherein the propylene homopolymer component continuous phase contains a large amount of ultrahigh molecular weight components. Preferably the molecular weight distribution M of the propylene homopolymer component_w/M_n(weight average molecular weight/number average molecular weight) 6-20, 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. Meanwhile, the content of the fraction having a molecular weight of more than 500 ten thousand is 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. Preferably, the propylene homopolymer component has a melt index, measured at 230 ℃ under a load of 2.16kg, of from 0.1 to 15g/10 min.

In a preferred embodiment of the present invention, the yields of the first propylene homopolymer and the second propylene homopolymer are in the range of from 40:60 to 60: 40. The polymerization reaction of the first step may be carried out in liquid-liquid phase, or in gas-gas phase, or using a combination of liquid-gas techniques. 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 second stage is between 55 and 100 ℃, preferably between 60 and 85 ℃; and/or the reaction temperature of the first stage is 50 to 100 ℃, preferably 60 to 85 ℃.

According to the method, two or more different types of external electron donors are respectively used in a plurality of reactors connected in series, the proper dosage of the external electron donor is selected, and the dosages of different chain transfer agent hydrogen in the reaction are combined to prepare the homo-polypropylene continuous phase with a specific melt index and extremely wide molecular weight distribution, which contains a large amount of ultrahigh molecular weight components. And further carrying out copolymerization of ethylene and 1-butene on the basis to obtain 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 polypropylene resin material with high melt strength effect.

In the second stage, it will be appreciated that the propylene homopolymer component stream contains unreacted catalyst from the first stage, which can continue to catalyze the polymerization in the second stage. In the second step, the 1-butene is preferably used in an amount such that the ratio of 1-butene to the total volume of 1-butene and ethylene is 0.2 to 0.8. Preferably, in the second step, the volume ratio of hydrogen to the total amount of 1-butene and ethylene is between 0.02 and 1.

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. Further preferably, the weight ratio of the ethylene/1-butene copolymer component to the propylene homopolymer component is from 11 to 80: 100.

By arranging the propylene homopolymer component of the base polypropylene resin material of the present invention to include a combination of at least two propylene homopolymers having different melt indices and having a specific ratio relationship, the base polypropylene resin material constituting the present invention has a specific dispersed phase, and with further combination of the dispersed phase and the rubber phase, an impact-resistant base polypropylene resin material having both high melt strength and good rigidity and toughness is produced.

In the present invention, in order to obtain an impact-resistant base polypropylene resin material having high melt strength and 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 can prepare the rubber phase with molecular weight distribution, ethylene content, which is favorable for achieving the object of the present invention, by these preferable conditions, thereby obtaining the base polypropylene resin material with better performance of impact resistance.

M of the Room temperature trichlorobenzene soluble Polypropylene obtained in the second step according to the Process of the invention_wM with trichlorobenzene insolubles at room temperature_wA ratio of greater than 0.5 and less than 1, preferably greater than 0.5 and less than 0.8; the ethylene/1-butene copolymer has a 1-butene content of 20 to 45% by weight. The rigidity and toughness of the polypropylene obtained in the way are further optimized, and simultaneously higher melt strength is ensured, so that a high-performance composition is obtained. In the present invention, the room temperature xylene solubles content is determined according to the method described in ASTM D5492. Here, it is to be easily understood that the "1-butene content in the ethylene/1-butene copolymer component" means the weight content of the 1-butene monomer constituting part in the ethylene/1-butene copolymer formed by copolymerizing the ethylene monomer and the 1-butene monomer. In the present invention, the content of the rubber phase is based on the xylene solubles content at room temperature. For ease of characterization, the molecular weight of the rubber phase is based on the molecular weight of the trichlorobenzene solubles. Among them, the yield ratio of the propylene/1-butene copolymer component (rubber phase) to the propylene homopolymer component is preferably 11 to 80: 100.

According to the process of the present invention, the base polypropylene resin having high melt impact resistance (i.e., the base PP-H resin) obtained in the second step has a melt index of 0.1 to 15g/10min, preferably 0.1 to 10g/10min, more preferably 0.1 to 6g/10min, as measured at 230 ℃ under a load of 2.16 kg. Basic PP-H resin having a molecular weight distribution M_w/M_nIs 4-10; m_z+1/M_wGreater than 10 and less than 20, preferably less than 15. According to the invention, it is preferred that the ratio of the melt index of the propylene homopolymer obtained in the first step to the melt index of the polypropylene is between 0.6 and 1. Among them, it is preferable that the content of 1-butene in the high melt strength impact resistant base PP-H resin is 5 to 20% by weight. The high melt impact base PP-H resin has a room temperature xylene solubles content of greater than 10 wt% and less than 30 wt%.

The preparation of the above-mentioned high melt strength impact resistant polypropylene material (i.e. base PP-H resin or base polypropylene resin) has been applied for patent (application No. CN2014106022998, an impact resistant polypropylene material with high melt strength and its preparation method). Incorporated herein by reference in its entirety.

In a preferred embodiment of the present invention, the method of the present invention further comprises further modifying the prepared polypropylene material with an α or β crystal nucleating agent to further increase the rigidity or toughness of the polypropylene material. Suitable alpha crystal and beta crystal nucleating agent modification is well known in the art. The ratio of the weight of the nucleating agent to the total weight of the polypropylene material is usually (0.005-3): 100.

In a specific embodiment of the present invention, the added second external electron donor can react with the catalytic activity center in the first stage homopolymerization product material to generate a new catalytic activity center, and propylene is continuously initiated to polymerize in the second stage to form a homopolymerization polymer with a molecular weight greatly different from that of the product obtained in the first 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. Therefore, the invention can obtain the homopolymerized polypropylene component containing a large amount of ultrahigh molecular weight fraction and wider molecular weight distribution under the condition of less hydrogen consumption by adjusting the dosage and the type of the external electron donor and the adding amount of the hydrogen at different stages when the homopolymerized polypropylene component is added into two reactors connected in series or is intermittently operated without using a special catalyst. And then controlling the composition, structure, content and the like of the rubber phase by controlling the reaction conditions of copolymerization reaction, for example, selecting proper 1-butene/(1-butene + ethylene), hydrogen/(1-butene + ethylene) and temperature and pressure, and further carrying out copolymerization reaction of ethylene and 1-butene on the basis of the homopolymerized polypropylene component to obtain the high melt strength impact polypropylene containing a certain content of rubber component with specific performance. 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 polypropylene resin material with excellent performance on the basis of setting a plurality of propylene homopolymerization stages and selecting the appropriate reaction parameters and reaction conditions of respective homopolymerization and copolymerization so as to generate the appropriate continuous phase and rubber dispersed phase and the combination relationship thereof, and the composition with excellent comprehensive performance is favorably obtained.

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 additives may also optionally be added.

For example, the high melt strength impact resistant base PP-H resin, the flame retardant, the conductive filler, and optionally the lubricant and other additives (optionally added) are directly mechanically mixed in a mechanical mixing device according to the proportion, and then the mixture is added into a melt blending device to be melt blended and granulated at the temperature of 170-200 ℃. Or respectively concentrating and blending a small amount of high-melt-strength impact-resistant basic PP-H resin and a flame retardant or a conductive filler, preparing flame-retardant master batches and antistatic master batches at 170-210 ℃, mixing the two master batches and the high-melt-strength impact-resistant basic PP-H resin in proportion, and granulating 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. For example, the flame retardant is preferably a halogen-free flame retardant, and the conductive filler is preferably a carbon material. The amount of the flame retardant is 10 to 50 parts, preferably 25 to 40 parts, and the amount of the conductive filler is 0.1 to 10 parts, preferably 0.75 to 3 parts, based on 100 parts by mass of the base polypropylene resin.

According to another aspect of the invention, the invention also provides a flame-retardant antistatic polypropylene pipe which is prepared from the composition or the composition prepared by the method. 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-H resin, the flame retardant and the conductive filler is used for preparing 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-H pipe extrusion process, and the obtained modified PP-H 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 polypropylene pipe, comprising:

s1, mixing the composition with an auxiliary agent, or preparing a flame-retardant antistatic polypropylene composition by the method and then mixing the flame-retardant antistatic 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 and/or a slipping agent, an anti-sticking agent and the like, and the extrusion performance, the flame retardant performance, the antistatic performance and the mechanical performance are not adversely affected.

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-H 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-H pipe with excellent flame-retardant, antistatic and impact-resistant properties.

Compared with the prior art, the flame-retardant antistatic high-performance PP-H pipe (such as a halogen-free flame-retardant antistatic high-performance PP-H pipe) provided by the invention still has excellent mechanical properties although being subjected to flame-retardant antistatic modification, and has higher melt strength, so that the torque during extrusion can be effectively reduced and the extrusion traction speed can be increased in the pipe extrusion processing process; 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 hydrostatic resistance of the halogen-free flame retardant antistatic high-performance PP-H pipe provided by the invention all meet the requirements of high-temperature industrial pollution discharge on the application of plastic pipes. And the preparation method is simple and effective and is easy to operate. The antistatic agent of carbon material series is used in the invention, which can generate synergistic effect with the flame retardant and is helpful for generating a compact carbon layer for obstructing flame and materials, thereby reducing the addition amount of the flame retardant. Not only can reduce the production cost of the pipe, but also can reduce the reduction of the hydrostatic pressure resistance of the pipe.

According to the invention, polypropylene with high melt strength and high strength performance is taken as a base resin, so that a flame-retardant antistatic PP-H composition with still higher processing performance and mechanical performance can be obtained after a certain amount of flame-retardant antistatic modifier is added, and a high-performance flame-retardant antistatic PP-H pipe is prepared by using the composition. And the PP-H pipe with excellent flame retardance, antistatic property, hydrostatic resistance and pipe extrusion processability can be prepared by using a general pipe extrusion process. The manufacturing process is simple and convenient, saves energy and is environment-friendly.

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:

the homopolymerized PP-H pipe material modified by beta crystal comprises the following components: jiangsu Basel polyolefin Inc., brand Beta-PPH-4011. The melt flow rate/(g/10 min) was 0.35, and the physical properties thereof compared with those of preparation examples 1 and 2 are shown in Table 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 (namely the content of a characterization rubber phase) is determined 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 (a CRYST-EX EQUIPMENT, IR4+ detector) produced by Spanish Polymer Char company, and the content of the xylene soluble substances at room temperature of the standard samples is determined by ASTM D5492.

(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 and 1-butene content: measured by a nuclear magnetic resonance method. The measurement was carried out using a 10 mm probe of AVANCEIII 400MHz nuclear magnetic resonance spectrometer (NMR) 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. required to carry out 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) Data concerning homo-polypropylene compositions herein, said simple beam notched impact strength: 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 performance of PP-H pipes prepared by the test examples and the comparative examples is tested, and the surface resistivity is measured according to the method specified in GB/T1410-; the oxygen index is measured according to the method specified in GB/T2406.1-2008. Hydrostatic resistance according to standard ISO15494: 2003: industrial applications Plastic pipe systems-polybutene, polyethylene and polypropylene-composition specifications and systems.

Preparation of the high melt strength base polypropylene resin:

preparation example 1

This preparation example is provided to illustrate the base polypropylene resin and the preparation method thereof provided by 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 of China petrochemical catalyst Co.), the cocatalyst (triethylaluminum) and the first external electron donor (isopropyl cyclopentyl dimethoxysilane, IPCPMS) 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 isopropylcyclopentyldimethoxysilane flow was 0.3g/hr, the procatalyst flow was 0.6g/hr, and the TEA/IPCPMS 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: homopolymerization of propylene

The first stage is as follows: continuously feeding the prepolymerized catalyst into a first loop reactor to complete the first-stage propylene homopolymerization, wherein the polymerization temperature of the first loop reactor 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 a first propylene homopolymer A.

And a second stage: isobutyl triethoxysilane (IBTES) was added at 0.63g/hr with propylene in the second loop reactor and mixed with the reactant stream from the first loop reactor with a TEA/IBTES ratio of 5(mol/mol), where IBTES is the second external electron donor. The polymerization temperature of the second loop reactor is 70 ℃, and the reaction pressure is 4.0 MPa; a quantity of hydrogen was also added with the propylene feed, the hydrogen concentration in the feed was 3300ppm by on-line chromatographic detection, and a second propylene homopolymer B was produced in the second loop reactor, yielding a propylene homopolymer fraction comprising a first propylene homopolymer and a second propylene homopolymer.

(3) The second step is that: copolymerization of ethylene and butadiene

A certain amount of hydrogen and H is added into the third reactor₂/(C₂+C₄)＝0.06(mol/mol)，C₄/(C₂+C₄)＝0.45(mol/mol)(C₂And C₄Respectively referring to ethylene and 1-butene), the reaction temperature was 75 ℃, and the ethylene/1-butene copolymerization was continuously initiated in the third reactor to produce the ethylene-1-butene copolymer component C.

The final product contains the first propylene homopolymer, the second propylene homopolymer and the ethylene-1-butene copolymer, and is subjected to wet nitrogen to remove the activity of the unreacted catalyst and heating and drying to obtain polymer powder. 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 1 and 2.

Preparation example 2

The preparation example is used to illustrate the polypropylene and the preparation method thereof provided by the invention.

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 second external electron donor was changed to 2, -isopropyl-2-isoamyl-1, 3-dimethoxypropane (IPPMP), the amount of the added was unchanged, and the amount of hydrogen in the second reactor was adjusted to 4000ppm in the second stage. 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 polypropylene resin material prepared according to the method of the present invention has high melt strength, and simultaneously has high tensile strength, flexural modulus, and notched impact strength. Therefore, the method provided by the invention can be used for preparing the base polypropylene resin material with high melt strength, high rigidity and high toughness. The basic polypropylene resin material with excellent performance has wide application value.

Example 1

This example illustrates the polypropylene composition and flame retardant antistatic PP-H 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-H composition granules. The notched Izod impact of the material at 23 ℃ was 27.3KJ/m²Oxygen index of 28.0 and surface resistance of 3 x 10⁶Ω。

(2) Preparing a flame-retardant antistatic PP-H 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 55.1%. The traction speed is 16.0 m/min. The flame-retardant antistatic PP-H 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:

the components are weighed and mixed according to the proportion, wherein the preparation example 1 is 100kg, the halogen-free flame retardant is 30kg, the conductive filler is 2kg, 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-H composition granules. The notched Izod impact of the material at 23 ℃ was 32.9KJ/m²Oxygen index of 34.9 and surface resistance of 2 x 10⁶Ω。

(2) Preparing a flame-retardant antistatic PP-H 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 12MPa, and after setting the appropriate screw speed, the torque was 52.2%. The drawing speed was 17.5 m/min. The flame-retardant antistatic PP-H 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 granular material A. 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-H composition granules. The notched Izod impact of the material at 23 ℃ was 41.3KJ/m²Oxygen index of 36.3 and surface resistance of 8 x 10⁵Ω。

(2) Preparing a flame-retardant antistatic PP-H 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 51.7%. The drawing speed is 18.5 m/min. The flame-retardant antistatic PP-H 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-H 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-H composition. The notched Izod impact of the material at 23 ℃ was 43.6KJ/m²Oxygen index of 35.8 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 11.5MPa, and the screw rotation speed and torque were 51.6% in accordance with example 1. The drawing speed is 18.5 m/min. The PP-H pipe basic performance test is carried out on the pipe, and the result is shown in Table 3.

Comparative example 1

Flame-retardant antistatic PP-H composition pellets 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 Beta-PPH-4011, which is a material of a homo-PP-H pipe, to obtain flame-retardant antistatic PP-H composition pellets. The notched Izod impact of the material at 23 ℃ was 23.2KJ/m²Oxygen index of 24.2 and surface resistance of 2 x 10⁸Ω。

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

Comparative example 2

Pellets of flame-retardant antistatic PP-H composition and polypropylene pipes were prepared in the same manner as in example 2, except that the polypropylene obtained in preparation example 2 was used in the same manner as in example 2The parts by weight of the homopolymerized PP-H pipe material Beta-PPH-4011 are replaced to obtain the flame-retardant antistatic PP-H composition granules. The notched Izod impact of the material at 23 ℃ was 26.1KJ/m²Oxygen index of 26.8 and surface resistance of 9 x 10⁷Ω。

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

Comparative example 3

Flame-retardant antistatic PP-H composition pellets 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 Beta-PPH-4011, which is a material of a homo-PP-H pipe, to obtain flame-retardant antistatic PP-H composition pellets. The notched Izod impact of the material at 23 ℃ was 37.2KJ/m²Oxygen index of 32.3 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 14MPa, and the screw rotation speed and torque were 66.0% in accordance with example 3. The drawing speed is 12 m/min. The PP-H pipe basic performance test is carried out on the pipe, and the result is shown in Table 3.

It can be seen from examples 1 to 4 that the high melt strength polypropylene of preparation examples 1 and 2 can be used as a base resin to prepare flame retardant antistatic PP-H composition pellets with excellent performances through flame retardant modification and antistatic modification. The high-strength flame-retardant antistatic PP-H pipe meeting the use requirement of a high-temperature industrial blow-off pipe can be prepared by adopting the general pipe extrusion process conditions. If a small amount of PP-H with high melt strength 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 PP-H with high melt strength are mixed in proportion for granulation to obtain flame-retardant antistatic PP-H composition granules, compared with the flame-retardant antistatic PP-H composition granules obtained by directly mixing the PP-H with high melt strength, the flame retardant, the conductive filler and the like in proportion and directly carrying out melt blending granulation, the compatibility of matrix resin and a modification auxiliary agent is improved, so that the prepared pipe has better performances.

As can be seen from comparative examples 1-2, compared with polypropylene tube materials in the market, such as Beta-crystal modified homopolymerized PP-H tube material Beta-PPH-4011 produced by Bassel of Jiangsu, preparation examples 1 and 2 have more excellent mechanical properties and processability before and after flame retardant and antistatic modification. 4011, after the flame-retardant antistatic modification is carried out in one step, the mechanical properties and processability are greatly reduced due to the addition of a large amount of microparticles incompatible with the matrix resin, and flame-retardant antistatic PP-H pipes cannot be prepared.

As can be seen from the comparative example 3, 4011 also adopts the process method of preparing the flame-retardant antistatic master batch by respectively preparing the flame-retardant master batch and then blending and melting to prepare the flame-retardant antistatic PP-H composition granules, although the produced pipes can pass the pipe performance test. 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 3 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-H composition provided by the invention can meet the requirements of high-temperature industrial sewage pipes 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 great economic benefits. The homopolymerized polypropylene pipe material used in the market at present needs to be added with an expensive beta nucleating agent to be close to the level of the high-performance PP-H pipe material.

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 polypropylene composition comprising a base polypropylene resin, a flame retardant and a conductive filler, said base polypropylene resin comprising a propylene homopolymer component and an ethylene/1-butene copolymer, wherein said propylene homopolymer component comprises at least a first propylene homopolymer and a second propylene homopolymer; the ratio of the Mw of the room-temperature trichlorobenzene soluble substance to the Mw of the room-temperature trichlorobenzene insoluble substance in the base polypropylene resin is more than 0.5 and less than 1; a room temperature xylene solubles content of greater than 10% by weight and less than 30% by weight; the content of 1-butene is 5-20 wt%; the molecular weight distribution Mw/Mn of the base polypropylene resin is 4 to 10; mz +1/Mw is from greater than 10 to less than 20; the base polypropylene resin has a melt index of 0.1-15g/10min measured at 230 ℃ under a load of 2.16 kg; the weight ratio of the ethylene/1-butene copolymer component to the propylene homopolymer component is 11-80: 100.

2. The composition of claim 1, wherein the ratio of the Mw of room temperature trichlorobenzene solubles to the Mw of room temperature trichlorobenzene insolubles in the base polypropylene resin is greater than 0.5 and less than 0.8.

3. The composition according to claim 1 or 2, wherein the weight of the flame retardant is 10 to 50 parts and the weight of the conductive filler is 0.1 to 10 parts, based on 100 parts by weight of the base polypropylene resin; and/or the flame retardant is a halogen-free flame retardant, and the conductive filler is a carbon material.

4. The composition of claim 3, wherein the flame retardant is present in an amount of 25 to 40 parts and the electrically conductive filler is present in an amount of 0.75 to 3 parts, based on 100 parts by weight of the base polypropylene resin.

5. Composition according to claim 1 or 2, characterized in that the butene content of the ethylene/1-butene copolymer component is comprised between 20 and 45% by weight; and/or a molecular weight polydispersity index of 4 to 8.

6. The composition of claim 5, wherein the base polypropylene resin has a molecular weight distribution Mz +1/Mw of from greater than 10 to less than 15; and/or a molecular weight polydispersity index of 4.5 to 6.

7. The composition according to claim 1 or 2, wherein the melt index ratio of the propylene homopolymer component to the base polypropylene resin is from 0.6:1 to 1: 1.

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

9. The composition of claim 7, wherein the base polypropylene resin has a melt index of 0.1 to 6.0g/10min measured at 230 ℃ under a load of 2.16 kg.

10. Composition according to claim 1 or 2, characterized in that the propylene homopolymer component has a molecular weight distribution Mw/Mn of 6 to 20; mz +1/Mn is greater than or equal to 70 and less than 150; and/or the weight ratio of the first propylene homopolymer to the second propylene homopolymer is from 40:60 to 60: 40.

11. Composition according to claim 10, characterized in that the propylene homopolymer fraction has a molecular weight distribution Mw/Mn of 10 to 16.

12. The composition according to claim 1 or 2, characterized in that the melt index of the first propylene homopolymer is smaller than the melt index of the second propylene homopolymer.

13. The composition of claim 12, wherein the first propylene homopolymer and the propylene homopolymer component have melt indices of 0.001 to 0.4g/10min and 0.1 to 15g/10min, respectively, as measured at 230 ℃ under a load of 2.16 kg.

14. The composition according to claim 1 or 2, further comprising a lubricant in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the base polypropylene resin.

15. 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 polypropylene resin.

16. A process for preparing the composition of any one of claims 1 to 15, comprising the steps of:

the first step is as follows: preparation of a propylene homopolymer component comprising:

the first stage is as follows: carrying out a propylene homopolymerization reaction in the presence or absence of hydrogen under the action of a Ziegler-Natta catalyst containing a first external electron donor to obtain a reactant flow containing a first propylene homopolymer;

and a second stage: adding a second external electron donor to perform a complex reaction with a catalyst in the reactant flow in the first stage, and then performing a propylene homopolymerization reaction in the presence of a first propylene homopolymer and hydrogen to generate a second propylene homopolymer, so as to obtain a propylene homopolymer component flow containing the first propylene homopolymer and the second propylene homopolymer;

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: carrying out a gas-phase copolymerization reaction of ethylene and 1-butene in the presence of the propylene homopolymer component stream obtained in the first step and hydrogen to produce an ethylene/1-butene copolymer component, to obtain a base polypropylene resin comprising the propylene homopolymer component and the ethylene/1-butene copolymer component;

17. The method of claim 16, wherein the flame retardant is a halogen-free flame retardant, the conductive filler is a carbon material; and/or, the weight of the flame retardant is 10-50 parts and the weight of the conductive filler is 0.1-10 parts based on 100 parts of the basic polypropylene resin.

18. The method of claim 17, wherein the flame retardant is 25 to 40 parts by weight and the conductive filler is 0.75 to 3 parts by weight, based on 100 parts by weight of the base polypropylene resin.

19. The method according to any one of claims 16 to 18, wherein in the third step, a lubricant is further added; and/or the blending is melt blending.

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

21. The process according to any one of claims 16 to 18, wherein in the second step the ratio of 1-butene to the total volume of ethylene and 1-butene is from 0.2:1 to 0.8:1, and/or the ratio of hydrogen to the total volume of ethylene and 1-butene is from 0.02:1 to 1: 1;

and/or, in the first step, the amount of hydrogen used in the second stage is 2000-; and/or the amount of hydrogen used in the first stage is 0-200 ppm.

22. The process according to any one of claims 16 to 18, 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 copolymerization step is 55-100 ℃.

23. The method of claim 22, 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 copolymerization step is 60-85 ℃.

24. The method of any one of claims 16-18, 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.

25. The process of claim 24, 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, dimethyldimethoxy, At least one of dimethyldiethoxysilane, diisobutyldimethoxysilane, methylcyclohexyldimethoxysilane, methylisobutyldimethoxysilane, dicyclohexyldimethoxysilane, methyl-isopropyldimethoxysilane, isopropyl-cyclopentyldimethoxysilane, dicyclopentyldimethoxysilane, isopropyl-isobutyldimethoxysilane, and diisopropyldimethoxysilane.

26. The method according to any one of claims 16 to 18, wherein the second external electron donor is selected from at least one compound of 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.

27. The method of claim 26, 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.

28. The process of any of claims 16 to 18, 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.

29. The method of claim 28, 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.

30. A flame retardant antistatic polypropylene pipe, which is prepared by using the composition of any one of claims 1 to 15 or the composition prepared by the method of any one of claims 16 to 29 as a raw material.

31. A method of making a flame retardant antistatic polypropylene pipe comprising:

s1 blending the composition as described in any one of claims 1 to 15 with an auxiliary agent, or preparing a flame-retardant antistatic polypropylene composition by the method as described in any one of claims 16 to 29, and then mixing the flame-retardant antistatic polypropylene composition with the auxiliary agent;

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.