High-performance metallocene floor heating pipe polyethylene resin and preparation method thereof

Abstract

The invention discloses a high-performance metallocene floor heating pipe polyethylene resin and a preparation method thereof, the high-performance metallocene floor heating pipe polyethylene resin comprises the following components by mass: 100 parts of polyethylene powder, 0.2-0.4 part of a composite antioxidant, 0.01-0.02 part of a high-activity metallocene catalyst, ethylene as a main raw material, hydrogen as a chain terminator, hexene-1 as a comonomer, and isopentane as an induced condensing agent. The preparation method comprises the following steps: adding polyethylene powder and a compounding agent into a reactor through a material feeding line, metering the polyethylene powder and the compounding agent according to a certain ratio, fully mixing, and extruding and granulating through a twin-screw extruder, thereby realizing the efficient and stable production of metallocene polyethylene resin products, creating greater economic benefits for enterprises, meeting the requirements of market product processing users, and having wide application prospects. Provided is a metallocene material having excellent thermal conductivity and heat resistance required for manufacturing a floor heating pipe.

Description

Technical Field

[0001] The invention relates to a polyethylene resin and a preparation method thereof, and more specifically, to a high-performance metallocene floor heating pipe polyethylene resin and a preparation method thereof, and belongs to the field of petrochemical industry. Background Art

[0002] Polyethylene resin is an important plastic material, widely used in packaging, construction, electronics, automobiles and other fields. Traditional polyethylene resin is usually prepared by Ziegler-Natta catalyst or chromium catalyst, but the polyethylene resin prepared by this type of catalyst has the disadvantages of wide molecular weight distribution and complex branched structure, which limits its application in some high-end fields. Metallocene catalyst, as a new type of catalyst, has the advantages of high activity, narrow molecular weight distribution, and controllable branched structure, and is widely used in the preparation of high-performance polyethylene resin. Floor heating system, as one of the important ways of heating in modern homes, has high requirements on the thermal conductivity, heat resistance and durability of pipes. Although traditional floor heating pipe materials can meet basic needs, there is still room for improvement in thermal conductivity efficiency and anti-aging performance. As a new type of polymer material, metallocene resin has great potential in the field of pipe manufacturing due to its unique molecular structure and performance. At present, the metallocene resin produced by domestic gas phase unipol process equipment mainly includes DGDE-3606 of Dushanzi Petrochemical and P3806R of Yangzhou Petrochemical, all of which have problems such as low production efficiency, unstable product quality and poor appearance performance. Summary of the invention

[0003] In order to solve the above-mentioned problems of the prior art, the present invention provides a high-performance metallocene floor heating pipe polyethylene resin and a preparation method thereof, which has technical characteristics such as being able to achieve efficient and stable production of metallocene polyethylene products.

[0004] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0005] The present invention discloses a high-performance metallocene floor heating pipe polyethylene resin, which comprises, by weight:

[0006] Polyethylene powder 100 parts

[0007] Compound antioxidant 0.2~0.4 parts

[0008] Highly active metallocene catalyst 0.01-0.02 parts

[0009] The high-activity metallocene catalyst is a coordination compound composed of metal atoms and aromatic cyclic hydrocarbon groups, and its components include, by mass fraction: [95% reaction product of the halide of the reaction product of alkyl-terminated (poly)alkylaluminoxane and silicon dioxide and bis(alkyl-alkylcyclopentadienyl) transition metal dihalide, isohexane <2.5%, phenylmethane <2%, stabilizer methylaluminoxane (balance <5%), and the catalyst activity is >3000.

[0010] According to the mass fraction, the antistatic agent includes: 50-75% heptane, dodecylbenzenesulfonic acid ≤10%, dimethyl dicocoalkyl ammonium nitrite ≤2.4%, 1-decene ≤0.3%;

[0011] According to the mass fraction, the high-efficiency composite antioxidant includes 80% composite antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) / antioxidant 168 (tris[2.4-di-tert-butylphenyl] phosphite), 10% heat stabilizer zinc stearate (zinc salt of octadecanoic acid), and 10% fluorine-containing elastomer additive FX5911.

[0012] Preferably, the preparation materials of the high-performance metallocene floor heating pipe polyethylene resin are subjected to a polymerization reaction in a polymerization reactor to obtain polyethylene resin, which is uniformly mixed in a mixer and extruded and granulated to obtain the high-performance metallocene floor heating pipe polyethylene resin.

[0013] Preferably, the polymerization temperature is controlled at 82-88°C, the total pressure is controlled at 2200-2300 kPa, the ethylene partial pressure is controlled at 1220-1350 kPa, the fluidizing gas velocity is 0.76-0.80 m / s, the antistatic agent ratio is 35 ppm, and H 2 / C 2 The concentration ratio is controlled at 1.3~2.0ppm / mol, C 6 / C 2 The concentration ratio is controlled at 0.006~0.007mol / mol.

[0014] Preferably, at 23°C, the density of the polyethylene resin is 0.933 to 0.939 g / cm 3 At 190°C, the melt mass flow rate is 0.4-0.8 g / 10 min, the tensile yield stress is ≥15 MPa, and the tensile fracture nominal strain is ≥500%.

[0015] Preferably, the high-performance metallocene floor heating pipe polyethylene resin has a tensile yield stress of ≥15 MPa, a tensile fracture nominal strain of ≥500%, and a bending modulus of ≥450 MPa.

[0016] The present invention discloses a method for preparing a high-performance metallocene floor heating pipe polyethylene resin, the method comprising the following steps:

[0017] Step 1): 140t of polyethylene powder is loaded into a polymerization reactor as a seed, 10-15ppm of an antistatic agent is added according to the weight of the seed in the polymerization reactor, and the amount of ethylene, hydrogen, hexene-1, and isopentane required for establishing a gas phase is introduced, and the final component concentration is adjusted to be ethylene: 55-65% mol, hexene-1: 0.5-0.7%, hydrogen: 60ppm, nitrogen 30-40% mol, and isopentane 4-5% mol;

[0018] Step 2): When the pressure of the polymerization reactor reaches 1.8 MPa, a highly active metallocene catalyst is injected. After the reaction is established, an antistatic agent is added to 20 to 60 ppm of the ethylene feed to carry out a polymerization reaction. The polymerization temperature is controlled at 82 to 88° C., and the polymerization ethylene partial pressure is reduced by 100 to 200 kPa.

[0019] Step 3) the polyethylene resin produced by the polymerization reaction is uniformly mixed with the compounding agent in a mixer at a mixer speed of 50 rpm for a mixing time of 5 to 10 min;

[0020] Step 4) Extruding and granulating the mixture through an extruder at a temperature of 200-260° C., an extruder feed rate of 40-58 t / h, and a screw speed of 282 rpm to obtain a finished product to obtain a high-performance metallocene floor heating pipe polyethylene resin.

[0021] Preferably, the compounding agent is added in an amount of 5.4 kg / t, and its ingredients include 80% of a composite antioxidant, 10% of a heat stabilizer, and 10% of a fluorine-containing elastomer additive.

[0022] Preferably, the composite antioxidant is one or both of antioxidant 1010 and antioxidant 168, the heat stabilizer is zinc stearate, and the fluorine-containing elastomer additive is fluorine-containing elastomer additive FX5911.

[0023] Preferably, the polymerization temperature is controlled at 82-88°C, the total reaction pressure is controlled at 2200-2300 kPa, the ethylene partial pressure is controlled at 1220-1350 kPa, the fluidizing gas velocity is 0.76-0.80 m / s, the antistatic agent ratio is 35 ppm, and H 2 / C 2 The concentration ratio is controlled at 1.3~2.0ppm / mol, C 6 / C 2 The concentration ratio is controlled at 0.006~0.007mol / mol.

[0024] Preferably, the antistatic agent used is prepared in advance with isopentane in a mass ratio of 1:4, stored in a special steel bottle, and transported to the polymerization reactor by a diaphragm pump.

[0025] Beneficial effects: the activity and selectivity of the polymerization reaction can be significantly improved, thereby obtaining a metallocene resin with a narrow molecular weight distribution and excellent performance; the invention controls the release of the catalyst activity in a gentle and slow manner by adjusting the polymerization process parameters to achieve high-load stable production, and the metallocene resin production device is the largest in China, with a stable production output of up to 58t / h; by matching specific extrusion granulation and product performance parameters, the produced resin has the performance of low yellowness index and less melt fracture; special compounding agents are selected to improve the processability of the resin, achieve stable granulation processing operation, and stably match the production of front and rear units, so as to achieve high production efficiency and stable product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the rotational rheological analysis diagram of the present invention.

[0027] Figure 2 It is the molecular weight and its distribution diagram of the present invention. DETAILED DESCRIPTION

[0028] The following is in conjunction with the instruction manual Figure 1-2 , the present invention is further illustrated, but the present invention is not limited to the following embodiments.

[0029] The high-performance metallocene floor heating pipe polyethylene resin of the present invention is mainly polymerized from raw materials ethylene and α-olefin, wherein the α-olefin is mainly 1-hexene, and is obtained by catalytic polymerization in a gas phase fluidized bed. Highly active metallocene catalyst 101B, produces a resin with a narrow relative molecular weight distribution and uniform branching degree. At the same time, the resin is granulated with a high-efficiency composite antioxidant component; the product has the advantages of static pressure resistance, strong environmental stress cracking resistance, and significant weight loss. During the processing, the extruder current and melt temperature are lower.

[0030] The low-odor polyethylene resin of the present invention is made from the following raw materials in parts by weight:

[0031] Polyethylene powder 100 parts

[0032] Compound antioxidant 0.2~0.4 parts

[0033] Highly active metallocene catalyst 0.01-0.02 parts

[0034] The highly active metallocene catalyst is commercially available, preferably from Grace 101B catalyst, which is a coordination compound composed of metal atoms and aromatic cyclic hydrocarbon groups, and has a variety of special chemical properties. Its main components are: [the reaction product of the halide of the reaction product of alkyl-terminated (poly) alkylaluminoxane and silicon dioxide and bis(alkyl-alkylcyclopentadienyl) transition metal dihalide (95% by mass), isohexane (<2.5%, by mass), phenylmethane (<2%, by mass), a small amount of impurities and stabilizer methylaluminoxane, the catalyst activity is>3000, preferably>5000.

[0035] The antistatic agent selected is preferably Statsafe provided by Innospec. TM 6000, whose main components are: heptane (50-75%, mass percentage), dodecylbenzenesulfonic acid (≤10%, mass percentage), dimethyl dicocoalkyl ammonium nitrite (≤2.4%, mass percentage), 1-decene (≤0.3%, mass percentage), which is used to improve the stability of continuous operation and prevent bed agglomeration. By strictly controlling the concentration of antistatic agent in the reactor, the effect on catalyst activity is small.

[0036] The preparation process uses a reaction system of a low-pressure gas-phase fluidized bed polyethylene production process (which is an existing technology and will not be described in detail). It consists of a fluidized bed reactor, a circulating gas compressor, a circulating gas cooler, and a material and catalyst feeding system. The selected fluidized bed reactor has simple product degassing, a stable product preparation process, good copolymerization performance, and excellent comprehensive performance of the prepared product.

[0037] Key control parameters of preparation: polymerization temperature is controlled at 82-88°C, preferably 85-88°C; total reaction pressure is controlled at 2200-2300 kPa; ethylene partial pressure is controlled at 1220-1350 kPa, preferably 125-1300 kPa; fluidizing gas velocity is 0.76-0.80 m / s, preferably 0.77-0.78 m / s; H 2 / C 2 The concentration ratio is controlled at 1.3-2.0 ppm / mol, preferably 1.5-1.9.0 ppm / mol; C 6 / C 2 The concentration ratio is controlled at 0.006-0.007 mol / mol. The product density (23°C) is 0.933-0.939 g / cm3, the melt mass flow rate (2.16 kg, 190°C) is 0.4-0.8 g / 10 min, the tensile yield stress is ≥15 MPa, preferably ≥18 MPa, and the tensile fracture nominal strain is ≥500%, preferably ≥600%.

[0038] The extruder adopts a fixed-frequency extruder of NISCO, model CIM510, with a rated power of 16800 kW. The speed of the main motor of the extruder is controlled to 1000 rpm, and the screw speed is reduced to 282 rpm. During the processing of the powder resin, the temperature of each section is controlled to 200-260° C., preferably 210-230° C., and the throttle valve opening is 400-500 mm, preferably 440-480 mm.

[0039] The high-efficiency composite antioxidant is a high-efficiency composite agent with strong thermal stability, low precipitation, and its main components are 80% composite antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) / antioxidant 168 (tris[2.4-di-tert-butylphenyl] phosphite), 10% heat stabilizer zinc stearate (zinc salt of octadecanoic acid), and 10% fluorine-containing elastomer additive FX5911.

[0040] Brief introduction to the process route of the preparation method of a high-performance metallocene floor heating pipe polyethylene resin of the present invention:

[0041] The reaction system of the low-pressure gas phase polyethylene production process is mainly composed of a fluidized bed reactor, a circulating gas compressor, a circulating gas cooler, and a material and catalyst feeding system. The production of the high-performance metallocene floor heating pipe polyethylene resin uses ethylene as the main raw material, hydrogen as a chain terminator, hexene-1 as a comonomer, and isopentane as an induced condensing agent, which are added to the reactor from the material feed line; ActivCat@101b main catalyst and STATSAFE 6000 are used as antistatic agents to maintain the normal progress of the polymerization reaction and adjust the product quality. The powder in the reactor is sent to the degassing bin for dehydrogenation and inactivation through the PDS system, and the block material is removed by screening with a vibrating screen, and then mixed with a certain proportion of additives and enters the extrusion granulation system for pelletizing. The gas phase components (nitrogen, isopentane, etc.) in the degassing bin are sent to the emission recovery system, pressurized and cooled to condense and liquefy them, and then sent back to the reactor by a high-speed pump. The tail gas is used as the conveying gas of the PDS system to achieve efficient utilization of various materials.

[0042] The steps of the preparation method of a high-performance metallocene floor heating pipe polyethylene resin of the present invention are as follows:

[0043] 1) The raw monomer is ethylene, the comonomer is hexene-1, the polymerization temperature is controlled at 82-88°C, the total reaction pressure is controlled at 2200-2300 kPa, the ethylene partial pressure is controlled at 1220-1350 kPa, the antistatic agent ratio is 35 ppm (ratio with ethylene feed), the H2 / C2 concentration ratio is controlled at 1.3-2.0 ppm / mol, and C 6 / C 2 The concentration ratio is controlled at 0.006-0.007 mol / mol. The product density (23°C) is 0.933-0.939 g / cm 3, melt mass flow rate (2.16kg, 190℃) is 0.4~0.8g / 10min, tensile yield stress is ≥15mpa, nominal strain at break is ≥500%, flexural modulus is ≥450mpa, yellowness index is <-3.0, and tailing is <25 / kg.

[0044] 2) used The 101B catalyst is packaged in barrels and is transferred to a steel cylinder using a dedicated metallocene catalyst feeding platform. The steel cylinder is then pressed into the dry powder feeding system and injected into the polymerization reactor through the carrier gas. TM 6000 is prepared in advance with isopentane at a mass ratio of 1:4, stored in a special steel cylinder, and transported to the reaction unit by a diaphragm pump;

[0045] 3) The production of high-performance metallocene floor heating pipe polyethylene resin described in the present invention is carried out according to the start-up steps of the unipol gas phase process. 140t of specific polyethylene powder is filled in the polymerization reactor as a seed, 10-15ppm of antistatic agent is added according to the weight of the reactor seed, and the amount of ethylene, hydrogen, hexene-1 and isopentane required to establish the gas phase are introduced, and the final component concentrations are adjusted to ethylene: 55-65% mol, hexene-1: 0.5-0.7%, hydrogen: 60ppm, nitrogen 30-40% mol, isopentane 4-5% mol. When the reactor pressure reaches 1.8 MPa, start the dry powder feeder system to inject a high-activity metallocene catalyst. After the reaction is established, control the antistatic agent to be added to 20-60ppm of the ethylene feed amount, preferably 32-38ppm;

[0046] 4) The polyethylene resin produced by the polymerization reaction is uniformly mixed with the compounding agent in a mixer after passing through a degassing system, the mixer speed is 50 rpm, the mixing time is 5 to 10 minutes, and then extruded and granulated into finished products through an extruder at a temperature of 200-260°C, an extruder feed of 40-58t / h, preferably 58t / h, and a screw speed of 282rpm. The polymerization of the present invention is controlled by parameters to ensure that the catalyst activity is released gently, and in the process of stably increasing the reaction load, the reaction polymerization heat is controlled to stabilize the reaction wall temperature. Specifically: the polymerization temperature is controlled at 82 to 88°C, preferably 85°C, 1220 to 1350kpa, preferably 1250kpa, and 10% of fluorine-containing additives are added to the compounding agent of the granulation unit to improve the resin processability.

[0047] Embodiment 1:

[0048] Polyethylene powder, polymerization temperature 85℃, reactor bed height 17.7m, reactor bed weight 136t, ethylene partial pressure 1300kPa, total reaction pressure 2272kPa, H 2 / C 2Concentration ratio 1.47ppm / mol, C 6 / C 2 Concentration ratio 0.007mol / mol, antistatic agent to ethylene ratio 33ppm, catalyst activity 4972kg / kg, compounding agent DGDZm-3606 (main components are 80% composite antioxidant, 10% heat stabilizer, 10% fluorine-containing elastomer additive). The above polyethylene powder and compounding agent are measured and fully mixed according to a certain ratio, and then extruded and granulated by a twin-screw extruder. The temperature of each zone of the extruder is 189℃, 210℃, 248℃, and 256℃.

[0049] The density of the obtained polyethylene resin product is 0.9355 g / cm 3 , melt mass flow rate 0.68g / 10min, tensile yield stress 16.3MPa, nominal strain at break 847%, simple supported beam notched impact strength 93kJ / m 2 , flexural modulus 609Mpa, yellow index -3.1, tailing 22 / kg.

[0050] Embodiment 2:

[0051] Polyethylene powder, polymerization temperature 85℃, reactor bed height 17.5m, reactor bed weight 129t, ethylene partial pressure 1320kPa, total reaction pressure 2260kPa, H 2 / C 2 Concentration ratio 1.49ppm / mol, C 6 / C 2 Concentration ratio 0.007mol / mol, antistatic agent to ethylene ratio 45ppm, catalyst activity 4751kg / kg, compounding agent DGDZm-3606 (main components are 80% composite antioxidant, 10% heat stabilizer, 10% fluorine-containing elastomer additive). The above polyethylene powder and compounding agent are measured and fully mixed according to a certain ratio, and then extruded and granulated by a twin-screw extruder. The temperature of each zone of the extruder is 180℃, 212℃, 248℃, and 258℃.

[0052] The density of the obtained polyethylene resin product is 0.9374 g / cm 3 , melt mass flow rate 0.62g / 10min, tensile yield stress 17.4MPa, nominal strain at break 889%, simple supported beam notched impact strength 73kJ / m 2 , flexural modulus 682Mpa, yellow index -3.2, tailing 21 / kg.

[0053] Embodiment 3:

[0054] Polyethylene powder, polymerization temperature 85℃, reactor bed height 17.8m, reactor bed weight 133t, ethylene partial pressure 1260kPa, total reaction pressure 2235kPa, H 2 / C 2 Concentration ratio 1.71ppm / mol, C 6 / C 2 Concentration ratio 0.007mol / mol, antistatic agent to ethylene ratio 35ppm, catalyst activity 5102kg / kg, compounding agent DGDZm-3606 (main components are 80% composite antioxidant, 10% heat stabilizer, 10% fluorine-containing elastomer additive). The above polyethylene powder and compounding agent are measured and fully mixed according to a certain ratio, and then extruded and granulated by a twin-screw extruder. The temperature of each zone of the extruder is 184℃, 217℃, 242℃, and 259℃.

[0055] The density of the obtained polyethylene resin product is 0.9372 g / cm 3 , melt mass flow rate 0.60g / 10min, tensile yield stress 17.7MPa, nominal strain at break 873%, simple supported beam notched impact strength 75kJ / m 2 , flexural modulus 677Mpa, yellow index -3.3, tailing 19 / kg.

[0056] Through the above embodiments, combined with Figure 1 , rotational rheological analysis: the intersection of the storage modulus and the loss modulus represents the point of mutual transformation between viscosity and elasticity. The modulus size Gx (Gx = G' = G") at the intersection can be used to qualitatively characterize the molecular weight of the polymer and the width of the molecular weight distribution. The horizontal position of Gx can be used to qualitatively analyze the average molecular weight. When Gx is to the left, the polymer has a higher weight average molecular weight Mw and long / multi-branched molecules; when Gx is to the right, the polymer has a lower weight average molecular weight Mw and short / few branched molecules. When Gx is upward, the molecular weight distribution is narrow; when Gx is downward, the molecular weight distribution is wide.

[0057] Combination Figure 2 , Molecular weight and its distribution: Test data show that the metallocene resin produced by the preparation method provided by the present invention has a narrow molecular weight distribution and excellent quality.

[0058] The present invention discloses a high-performance metallocene polyethylene resin for floor heating pipes and a preparation method thereof, which realizes efficient and stable production of metallocene polyethylene resin products, creates greater economic benefits for enterprises, and at the same time meets the needs of product processing users in the market, and provides a metallocene material with excellent thermal conductivity and heat resistance required for floor heating pipe manufacturing.

[0059] Finally, it should be noted that the present invention is not limited to the above embodiments, and there are many variations. All variations that can be directly derived or associated with the content disclosed by ordinary technicians in this field should be considered as the protection scope of the present invention.

Claims

1. A high-performance metallocene floor heating pipe polyethylene resin, characterized in that: According to the mass percentage, it includes: Polyethylene powder 100 parts Compound antioxidant 0.2~0.4 parts Highly active metallocene catalyst 0.01-0.02 parts The high-activity metallocene catalyst is a coordination compound composed of metal atoms and aromatic cyclic hydrocarbon groups, and its components include, by mass fraction: [95% reaction product of the reaction product of alkyl-terminated (poly)alkylaluminoxane and silicon dioxide and bis(alkyl-alkylcyclopentadienyl) transition metal dihalide, isohexane <2.5%, phenylmethane <2%, balance of stabilizer methylaluminoxane <5%, catalyst activity >3000; According to the mass fraction, the antistatic agent includes: 50-75% heptane, dodecylbenzenesulfonic acid ≤10%, dimethyl dicocoalkyl ammonium nitrite ≤2.4%, 1-decene ≤0.3%; According to the mass fraction, the high-efficiency composite antioxidant includes 80% composite antioxidant 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) / antioxidant 168 (tris[2.4-di-tert-butylphenyl] phosphite), 10% heat stabilizer zinc stearate (zinc salt of octadecanoic acid), and 10% fluorine-containing elastomer additive FX5911.

2. A high-performance metallocene floor heating pipe polyethylene resin according to claim 1, characterized in that: The preparation materials of the high-performance metallocene floor heating pipe polyethylene resin are subjected to a polymerization reaction in a polymerization reactor to obtain polyethylene resin, which is uniformly mixed in a mixer and extruded and granulated to obtain the high-performance metallocene floor heating pipe polyethylene resin.

3. A high-performance metallocene floor heating pipe polyethylene resin according to claim 2, characterized in that: The polymerization reaction temperature is controlled at 82-88°C, the total pressure is controlled at 2200-2300 kPa, the ethylene partial pressure is controlled at 1220-1350 kPa, the fluidizing gas velocity is 0.76-0.80 m / s, the antistatic agent ratio is 35 ppm, the H2 / C2 concentration ratio is controlled at 1.3-2.0 ppm / mol, and the C6 / C2 concentration ratio is controlled at 0.006-0.007 mol / mol.

4. A high-performance metallocene floor heating pipe polyethylene resin according to claim 2 or 3, characterized in that: At 23°C, the density of polyethylene resin is 0.933-0.939 g / cm 3 At 190°C, the melt mass flow rate is 0.4-0.8 g / 10 min, the tensile yield stress is ≥15 MPa, and the tensile fracture nominal strain is ≥500%.

5. The high-performance metallocene floor heating pipe polyethylene resin according to claim 2, characterized in that: The high-performance metallocene floor heating pipe polyethylene resin has a tensile yield stress of ≥15 MPa, a tensile fracture nominal strain of ≥500%, and a bending modulus of ≥450 MPa.

6. A method for preparing a high-performance metallocene floor heating pipe polyethylene resin, characterized in that The method comprises the following steps: Step 1): 140t of polyethylene powder is loaded into a polymerization reactor as a seed, 10-15ppm of an antistatic agent is added according to the weight of the seed in the polymerization reactor, and the amount of ethylene, hydrogen, hexene-1, and isopentane required for establishing a gas phase is introduced, and the final component concentration is adjusted to be ethylene: 55-65% mol, hexene-1: 0.5-0.7%, hydrogen: 60ppm, nitrogen 30-40% mol, and isopentane 4-5% mol; Step 2): When the pressure of the polymerization reactor reaches 1.8 MPa, a highly active metallocene catalyst is injected. After the reaction is established, an antistatic agent is added to 20 to 60 ppm of the ethylene feed to carry out a polymerization reaction. The polymerization temperature is controlled at 82 to 88° C., and the polymerization ethylene partial pressure is reduced by 100 to 200 kPa. Step 3) the polyethylene resin produced by the polymerization reaction is uniformly mixed with the compounding agent in a mixer at a mixer speed of 50 rpm for a mixing time of 5 to 10 min; Step 4) Extrusion granulation is performed through an extruder at a temperature of 200-260° C., an extruder feed of 40-58 t / h, and a screw speed of 282 rpm to obtain a finished product to obtain a high-performance metallocene floor heating pipe polyethylene resin.

7. The method for preparing a high-performance metallocene floor heating pipe polyethylene resin according to claim 6, characterized in that: The compounding agent used has an addition ratio of 5.4 kg / t, and its ingredients include 80% of a compound antioxidant, 10% of a heat stabilizer, and 10% of a fluorine-containing elastomer additive.

8. The method for preparing a high-performance metallocene floor heating pipe polyethylene resin according to claim 7, characterized in that: The composite antioxidant is one or both of antioxidant 1010 and antioxidant 168, the heat stabilizer is zinc stearate, and the fluorine-containing elastomer additive is fluorine-containing elastomer additive FX5911.

9. The method for preparing a high-performance metallocene floor heating pipe polyethylene resin according to claim 6, characterized in that: The polymerization reaction temperature is controlled at 82-88°C, the total reaction pressure is controlled at 2200-2300 kPa, the ethylene partial pressure is controlled at 1220-1350 kPa, the fluidizing gas velocity is 0.76-0.80 m / s, the antistatic agent ratio is 35 ppm, the H2 / C2 concentration ratio is controlled at 1.3-2.0 ppm / mol, and the C6 / C2 concentration ratio is controlled at 0.006-0.007 mol / mol.

10. The method for preparing a high-performance metallocene floor heating pipe polyethylene resin according to claim 6, characterized in that: The antistatic agent used is prepared in advance with isopentane at a mass ratio of 1:4, stored in a special steel cylinder, and transported to the polymerization reactor by a diaphragm pump.

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