CN113121732A - High-density polyethylene resin for rotational molding, and preparation method and application thereof - Google Patents

High-density polyethylene resin for rotational molding, and preparation method and application thereof Download PDF

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CN113121732A
CN113121732A CN202010043595.4A CN202010043595A CN113121732A CN 113121732 A CN113121732 A CN 113121732A CN 202010043595 A CN202010043595 A CN 202010043595A CN 113121732 A CN113121732 A CN 113121732A
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rotational molding
polyethylene resin
catalyst
density polyethylene
kettle
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王健
郭洪元
王俊荣
崔月
张利粉
王大明
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Petrochina Co Ltd
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Petrochina Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
    • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
    • C08K5/005—Stabilisers against oxidation, heat, light, ozone
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/06—Properties of polyethylene
    • C08L2207/062—HDPE

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Moulding By Coating Moulds (AREA)
  • Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)

Abstract

The invention provides a high-density polyethylene resin for rotational molding, and a preparation method and application thereof. The preparation method comprises the following steps: dispersing magnesium ethoxide in C6～C13Forming a pre-dispersion liquid in the straight-chain alkane, adding titanium tetrachloride into the pre-dispersion liquid, and reacting to obtain a catalyst; putting a catalyst, a dispersing agent and a cocatalyst in a Hoechst slurry kettle type reactor, raising the temperature of the kettle to 48-52 ℃, introducing ethylene and alpha-olefin into the kettle, andintroducing hydrogen, and reacting at the reaction temperature of 80-86 ℃ and the pressure of 0.6-1.0 MPa to obtain polymer slurry; and separating and drying the polymer slurry to obtain the high-density polyethylene resin for rotational molding. The invention adopts the Hoechst slurry method to directly produce the special material for the high-density polyethylene resin rotational molding powder, can reduce the problems of advanced crosslinking and performance reduction in the particle grinding process, saves the grinding cost, and can be directly used for producing rotational molding products.

Description

High-density polyethylene resin for rotational molding, and preparation method and application thereof
Technical Field
The invention relates to the technical field of high polymer materials, in particular to a high-density polyethylene resin for rotational molding, and a preparation method and application thereof.
Background
Chinese patent 200910213313.4 relates to a polyethylene composition for rotational molding, which comprises linear low density polyethylene, surface modified carbon nanofibers, an antioxidant and a light stabilizer, and is prepared by melt granulation by a twin-screw extruder. The composition is easy to change material properties in the process of extrusion granulation, and the possibility of premature crosslinking and thermosetting change exists. Chinese patent 201010506076.3 relates to a special material for silane crosslinked polyethylene rotational molding, which is produced by the working procedures of reaction extrusion, grinding and the like of a plurality of raw materials. However, the material is ground to a specific particle size before use to meet the requirements of the rotational molding process, while the grinding of the thermoplastic resin at normal temperature is difficult, and if the material has high rigidity, the material is easy to generate heat and adhere during grinding, so that the risk of premature crosslinking during grinding exists, and a proper grinding process and a cooling mode are required to successfully grind the qualified crosslinked polyethylene powder for rotational molding.
In summary, the problem of premature crosslinking of the resin often exists when polyethylene resins for rotational molding are prepared at present, which leads to the reduction of the physical properties of the final rotational molded product.
Disclosure of Invention
The invention mainly aims to provide a high-density polyethylene resin for rotational molding, a preparation method and application thereof, and aims to solve the problem that the prior art is difficult to avoid advanced crosslinking during preparation of the polyethylene resin for rotational molding so as to influence the physical properties of rotational molding products.
To achieve the above object, according to one aspect of the present invention, there is providedA preparation method of high-density polyethylene resin for rotational molding is disclosed, which comprises the following steps: dispersing magnesium ethoxide in C6～C13Forming a pre-dispersion liquid in the straight-chain alkane, adding titanium tetrachloride into the pre-dispersion liquid, and reacting to obtain a catalyst; placing a catalyst, a dispersing agent and a cocatalyst in a Hoechst slurry kettle type reactor, raising the temperature of the kettle to 48-52 ℃, introducing ethylene and alpha-olefin into the kettle, introducing hydrogen, and reacting at the reaction temperature of 80-86 ℃ and the pressure of 0.6-1.0 MPa to obtain polymer slurry; and separating and drying the polymer slurry to obtain the high-density polyethylene resin for rotational molding.
Further, the α -olefin is 1-hexene and/or 1-octene.
Further, the volume ratio of the ethylene to the hydrogen is 4.5-7.5: 1, and the volume ratio of the ethylene to the alpha-olefin is 25-50: 1.
Further, C6～C13The straight-chain alkane is one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, undecane and dodecane.
Further, the dispersant is one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, undecane and dodecane, preferably n-hexane, and the cocatalyst is alkylaluminum AlRnX3-nWherein R is C1～C10X is halogen, preferably chlorine or bromine, 0 < n.ltoreq.3.
Furthermore, the weight ratio of the catalyst, the dispersant and the cocatalyst is 1 (0.5 multiplied by 10)6～4×106):(100～500)。
Further, the step of preparing the catalyst comprises: magnesium ethoxide and C6～C13Mixing the straight-chain alkane, and performing pre-dispersion at a stirring speed of 100-1000 rpm and a temperature of 60-130 ℃ to obtain a pre-dispersion liquid; cooling the pre-dispersion liquid to-20 to-10 ℃, dripping titanium tetrachloride into the pre-dispersion liquid, and reacting for 3 to 5 hours at a stirring speed of 100 to 1000rpm to obtain a reaction liquid; and filtering, washing and pre-activating the reaction liquid to obtain the catalyst.
Further, magnesium ethoxide with C6～C13The weight ratio of the straight-chain alkane is 1: 10-100, and the weight ratio of the titanium tetrachloride to the magnesium ethoxide is 130-20: 1.
Furthermore, the reaction time of the ethylene, the alpha-olefin and the hydrogen is 1-3 h.
According to another aspect of the invention, the high-density polyethylene resin for rotational molding is prepared by the preparation method, and the density of the high-density polyethylene resin for rotational molding is 0.944-0.950 g/cm3A melt index of 3 to 6g/10min and a bulk density of 0.36 to 0.40g/cm3The particle size of the powder is larger than 75% of the total amount and is 125-200 meshes.
According to another aspect of the invention, the invention further provides a rotational molding method of polyethylene resin, which is to mix the high-density polyethylene resin for rotational molding with an antioxidant and an anti-ultraviolet agent and obtain a polyethylene resin rotational molding product through rotational molding processing, wherein the weight ratio of the high-density polyethylene resin to the antioxidant and the anti-ultraviolet agent is 1000 (2-20): 1-10.
The preparation method of the high-density polyethylene resin for rotational molding provided by the invention comprises the following steps: dispersing magnesium ethoxide in C6～C13Forming a pre-dispersion liquid in the straight-chain alkane, adding titanium tetrachloride into the pre-dispersion liquid, and reacting to obtain a catalyst; placing a catalyst, a dispersing agent and a cocatalyst in a Hoechst slurry kettle type reactor, raising the temperature of the kettle to 48-52 ℃, introducing ethylene and alpha-olefin into the kettle, introducing hydrogen, and reacting at the reaction temperature of 80-86 ℃ and the pressure of 0.6-1.0 MPa to obtain polymer slurry; and separating and drying the polymer slurry to obtain the high-density polyethylene resin for rotational molding. The invention adopts the Hoechst slurry method to directly produce the special material for the high-density polyethylene resin rotational molding powder, can reduce the problems of advanced crosslinking and performance reduction in the particle grinding process, can save the grinding cost, and can be directly used for producing rotational molding products.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
As described in the background section, the prior art has many problems in preparing polyethylene resins for rotomoulding, such as premature crosslinking leading to a decrease in the physical properties of the final rotomoulded articles. In order to solve the problem, the present invention provides a method for preparing a high density polyethylene resin for rotational molding, comprising the steps of: dispersing magnesium ethoxide in C6～C13Forming a pre-dispersion liquid in the straight-chain alkane, adding titanium tetrachloride into the pre-dispersion liquid, and reacting to obtain a catalyst; placing a catalyst, a dispersing agent and a cocatalyst in a Hoechst slurry kettle type reactor, raising the temperature of the kettle to 48-52 ℃, introducing ethylene and alpha-olefin into the kettle, introducing hydrogen, and reacting at the reaction temperature of 80-86 ℃ and the pressure of 0.6-1.0 MPa to obtain polymer slurry; and separating and drying the polymer slurry to obtain the high-density polyethylene resin for rotational molding.
The invention adopts a Hoechst slurry method, takes magnesium ethoxide/titanium tetrachloride as a catalyst, is matched with a dispersant and a cocatalyst, and polymerizes ethylene and alpha-olefin under special reaction temperature and pressure, directly produces the special material for the high-density polyethylene resin rotational molding powder, can reduce the problems of advanced crosslinking and performance reduction in the particle grinding process, can save grinding cost, and can be directly used for the production of rotational molding products. The high-density polyethylene resin for rotational molding has good mechanical property and processability. The resin is used as raw material and is made into various products by a rotational molding process, the ESCR of the resin is more than 1100 hours, and the elongation at break of the resin is more than 600 percent.
In order to further improve the overall properties of the high density polyethylene, in a preferred embodiment the alpha-olefin is 1-hexene and/or 1-octene. More preferably, the volume ratio of ethylene to hydrogen is 4.5 to 7.5:1 and the volume ratio of ethylene to alpha-olefin is 25 to 50: 1.
In order to disperse the magnesium ethoxide more sufficiently to improve the catalytic activity of the catalyst, in a preferred embodiment, C is added6～C13The straight-chain alkane is one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, undecane and dodecaneAnd (4) seed preparation. More preferably, the dispersant is n-hexane and the cocatalyst is aluminum alkyl AlRnX3-nWherein R is C1～C10X is halogen, preferably chlorine or bromine, 0 < n.ltoreq.3.
In a preferred embodiment, the weight ratio of the catalyst, the dispersant and the cocatalyst is 1 (0.5X 10)6～4×106) 100 to 500. The proportion of the three components is controlled in the range, which is favorable for further improving the efficiency of polymerization reaction and avoiding raw materials caused by excessive catalyst and the like.
In a preferred embodiment, the step of preparing the catalyst comprises: magnesium ethoxide and C6～C13Mixing the straight-chain alkane, and performing pre-dispersion at a stirring speed of 100-1000 rpm and a temperature of 60-130 ℃ to obtain a pre-dispersion liquid; cooling the pre-dispersion liquid to-20 to-10 ℃, dripping titanium tetrachloride into the pre-dispersion liquid, and reacting for 3 to 5 hours at a stirring speed of 100 to 1000rpm to obtain a reaction liquid; and filtering, washing and pre-activating the reaction liquid to obtain the catalyst. Under the above reaction conditions, the magnesium ethoxide is firstly dispersed in C6～C13And the distribution is more uniform in the straight-chain alkane. After the temperature is reduced, titanium tetrachloride is added in a dropwise manner, so that the dropwise adding process is safer, the reaction is more stable, and the titanium tetrachloride can be better dispersed and can be more fully contacted with magnesium ethoxide. After the reaction is carried out for 3-5 hours at the stirring speed of 100-1000 rpm, the reaction between the two is more sufficient, the formed catalyst has larger specific surface area and higher catalytic activity, and the efficiency of subsequent polymerization reaction is improved. More preferably, magnesium ethoxide is reacted with C6～C13The weight ratio of the straight-chain alkane is 1: 10-100, and the weight ratio of the titanium tetrachloride to the magnesium ethoxide is 130-20: 1.
In order to obtain a high density polyethylene resin with a more suitable molecular weight, in a preferred embodiment, the reaction time of ethylene, alpha-olefin and hydrogen is 1 to 3 hours.
In the actual operation process, after the polymerization reaction is finished, the Hoechst slurry tank reactor is cooled to normal temperature, then the material is discharged, and then the polymer slurry is separated and dried. The specific separation and drying method can adopt a method commonly used in the field of organic synthesis, and more preferably adopts a flash evaporation method to separate the catalyst.
According to another aspect of the invention, the high-density polyethylene resin for rotational molding prepared by the preparation method is provided, and the density of the high-density polyethylene resin for rotational molding is 0.944-0.950 g/cm3A melt index (5kg) of 3 to 6g/10min and a bulk density of 0.36 to 0.40g/cm3The particle size of the powder is larger than 75% of the total amount and is 125-200 meshes. The high-density polyethylene resin for rotational molding can be directly used as a rotational molding powder material, does not need to be ground, and has good machining performance and good product mechanical performance.
According to another aspect of the present invention, there is also provided a rotational molding method of a polyethylene resin, comprising: mixing the high-density polyethylene resin for rotational molding with an antioxidant, and performing rotational molding processing to obtain a polyethylene resin rotational molding product, wherein the weight ratio of the polyethylene resin to the antioxidant to the ultraviolet resistant agent is 1000 (2-20) to (1-10). The high-density polyethylene resin prepared by the process is subjected to rotational molding, the product has excellent performance, the ESCR is more than 1100 hours, and the elongation at break is more than 600%.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
Example 1
Adding magnesium ethoxide and paraffin n-decane into a catalyst preparation kettle, stirring at the rotation speed of 200rpm, cooling to-20 ℃ at the temperature after full dissolution at 60 ℃, dropwise adding titanium tetrachloride, stirring at the rotation speed of 300rpm, controlling a certain dropwise adding speed at 10ml/h, reacting for 3 hours, filtering, and washing for 5 times to obtain a catalyst; the weight ratio of magnesium ethoxide to paraffin in the process is 1:10, and the weight ratio of titanium tetrachloride to magnesium ethoxide is 20: 1. Adding a catalyst, a dispersant n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersant n-hexane to the cocatalyst alkyl aluminum is 1:0.5 multiplied by 106100, namely; when the temperature of the kettle rises to 50 ℃, ethylene and comonomer 1-hexene are introduced(the volume ratio of the two is 25:1), introducing hydrogen, controlling the reaction temperature at 80 ℃ and the reaction pressure at 0.6Mpa, reacting for 2 hours, cooling, discharging and drying to obtain the polyethylene powder.
The polyethylene resin has a density of 0.948g/cm3The melt index (5kg) was 6g/10min, and the bulk density was 0.38g/cm3The particle size of the powder is larger than 85% of the total amount between 125 and 200 meshes.
99.0 percent (mass fraction) of high-density polyethylene powder, 0.2 percent (mass fraction) of antioxidant and 0.8 percent (mass fraction) of ultraviolet resistant agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 600%.
Example 2
Adding magnesium ethoxide and paraffin n-octane into a catalyst preparation kettle, stirring at the rotation speed of 250rpm, cooling to-20 ℃ at the temperature of 80 ℃ after full dissolution, dropwise adding titanium tetrachloride, stirring at the rotation speed of 350rpm, controlling a certain dropwise adding speed to be 20ml/h, reacting for 3.5 hours, filtering, and washing for 5 times to obtain a catalyst; the weight ratio of magnesium ethoxide to paraffin in the process was 1:30, and the weight ratio of titanium tetrachloride to magnesium ethoxide was 50: 1. Adding a catalyst, a dispersant n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersant n-hexane to the cocatalyst alkyl aluminum is 1:1.5 multiplied by 106200, namely; when the temperature of the kettle rises to 50 ℃, introducing ethylene and comonomer 1-octene (the volume ratio of the ethylene to the comonomer is 40:1), introducing hydrogen, controlling the reaction temperature at 80 ℃ and the reaction pressure at 0.8Mpa, reacting for 2 hours, cooling, discharging and drying to obtain polyethylene powder.
The polyethylene resin had a density of 0.950g/cm3Melt index (5kg) of 4.5g/10min and bulk density of 0.37g/cm3The powder particle size is larger than 80% of the total amount between 125-200 meshes.
98.5 percent (mass fraction) of high-density polyethylene powder, 1.2 percent (mass fraction) of antioxidant and 0.3 percent (mass fraction) of ultraviolet resistant agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 650%.
Example 3
Adding magnesium ethoxide and paraffin n-decane into a catalyst preparation kettle, stirring at the rotation speed of 250rpm, cooling to-15 ℃ at the temperature after fully dissolving at 100 ℃, dropwise adding titanium tetrachloride, stirring at the rotation speed of 400rpm, controlling a certain dropwise adding speed to be 25ml/h, reacting for 3.5 hours, filtering, and washing for 5 times to obtain a catalyst; in the process, the weight ratio of magnesium ethoxide to paraffin is 1:80, and the weight ratio of titanium tetrachloride to magnesium ethoxide is 100: 1. Adding a catalyst, a dispersing agent n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersing agent n-hexane to the cocatalyst alkyl aluminum is 1: 3X 106450, respectively; when the temperature of the kettle rises to 50 ℃, introducing ethylene and comonomer 1-hexene (the volume ratio of the ethylene to the comonomer is 50:1), introducing hydrogen, controlling the reaction temperature at 83 ℃ and the reaction pressure at 1.0Mpa, reacting for 2 hours, cooling, discharging and drying to obtain polyethylene powder.
The polyethylene resin has a density of 0.947g/cm3The melt index (5kg) was 3g/10min, and the bulk density was 0.39g/cm3The powder particle size is larger than 88% of the total amount between 125-200 meshes.
97 percent (mass fraction) of high-density polyethylene powder, 2 percent (mass fraction) of antioxidant and 1 percent (mass fraction) of ultraviolet resistant agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 610%.
Example 4
Adding magnesium ethoxide and paraffin n-heptane into a catalyst preparation kettle, stirring at the rotation speed of 250rpm, cooling to-15 ℃ at the temperature of 130 ℃ after full dissolution, dropwise adding titanium tetrachloride, stirring at the rotation speed of 350rpm, controlling a certain dropwise adding speed to be 40ml/L, reacting for 4 hours, filtering, and washing for 5 times to obtain a catalyst; the weight ratio of magnesium ethoxide to paraffin in the process is 1:50, and the weight ratio of titanium tetrachloride to magnesium ethoxide is 110: 1. Adding a catalyst, a dispersant n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersant n-hexane to the cocatalyst alkyl aluminum is 1:4 multiplied by 106400, preparing a mixture; when the temperature of the kettle rises to 50 ℃, introducing ethylene and comonomer 1-octene (the volume ratio of the ethylene to the comonomer is 50:1), and introducing hydrogenControlling the reaction temperature at 86 ℃ and the reaction pressure at 0.8Mpa, reacting for 2 hours, cooling, discharging and drying to obtain the polyethylene powder.
The polyethylene resin had a density of 0.950g/cm3Melt index (5kg) of 4.5g/10min and bulk density of 0.37g/cm3The powder particle size is larger than 80% of the total amount between 125-200 meshes.
97.5 percent (mass fraction) of high-density polyethylene powder, 1.5 percent (mass fraction) of antioxidant and 1 percent (mass fraction) of ultraviolet resistant agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 600%.
Example 5
Adding magnesium ethoxide and paraffin n-decane into a catalyst preparation kettle, stirring at the rotating speed of 300rpm, cooling to-10 ℃ at the temperature after full dissolution at 130 ℃, dropwise adding titanium tetrachloride, stirring at the rotating speed of 500rpm, controlling a certain dropwise adding speed to be 50ml/h, reacting for 4 hours, filtering, and washing for 5 times to obtain a catalyst; the weight ratio of magnesium ethoxide to paraffin in the process was 1:100, and the weight ratio of titanium tetrachloride to magnesium ethoxide was 130: 1. Adding a catalyst, a dispersant n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersant n-hexane to the cocatalyst alkyl aluminum is 1:1.5 multiplied by 106500, and then mixing; when the temperature of the kettle rises to 50 ℃, introducing ethylene and comonomer 1-hexene (the volume ratio of the ethylene to the comonomer is 50:1), introducing hydrogen, controlling the reaction temperature at 83 ℃ and the reaction pressure at 1.0Mpa, reacting for 2 hours, cooling, discharging and drying to obtain polyethylene powder.
The polyethylene resin had a density of 0.950g/cm3Melt index (5kg) of 4.5g/10min and bulk density of 0.37g/cm3The powder particle size is larger than 80% of the total amount between 125-200 meshes.
98 percent (mass fraction) of high-density polyethylene powder, 1.5 percent (mass fraction) of antioxidant and 0.5 percent (mass fraction) of ultraviolet resistant agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 650%.
Example 6
Adding magnesium ethoxide and paraffin n-decane into a catalyst preparation kettle, stirring at the rotating speed of 300rpm, cooling to-10 ℃ at the temperature after full dissolution at 130 ℃, dropwise adding titanium tetrachloride, stirring at the rotating speed of 800rpm, controlling a certain dropwise adding speed to be 20ml/h, reacting for 5 hours, filtering, and washing for 5 times to obtain a catalyst; the weight ratio of magnesium ethoxide to paraffin in the process was 1:50, and the weight ratio of titanium tetrachloride to magnesium ethoxide was 130: 1. Adding a catalyst, a dispersant n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersant n-hexane to the cocatalyst alkyl aluminum is 1:4 multiplied by 106100, namely; when the temperature of the kettle rises to 50 ℃, introducing ethylene and comonomer 1-octene (the volume ratio of the ethylene to the comonomer is 25:1), introducing hydrogen, controlling the reaction temperature at 80 ℃ and the reaction pressure at 1.0Mpa, reacting for 2 hours, cooling, discharging and drying to obtain polyethylene powder.
The polyethylene resin had a density of 0.950g/cm3Melt index (5kg) of 4.5g/10min and bulk density of 0.37g/cm3The powder particle size is larger than 80% of the total amount between 125-200 meshes.
99 percent (mass fraction) of high-density polyethylene powder, 0.5 percent (mass fraction) of antioxidant and 0.5 percent (mass fraction) of anti-ultraviolet agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 610%.
Example 7
Adding magnesium ethoxide and paraffin n-decane into a catalyst preparation kettle, stirring at the rotating speed of 300rpm, cooling to-10 ℃ at the temperature after full dissolution at 100 ℃, dropwise adding titanium tetrachloride, stirring at the rotating speed of 1000rpm, controlling a certain dropwise adding speed, reacting for 5 hours at a speed of 25ml/h, filtering, and washing for 5 times to obtain a catalyst; the weight ratio of magnesium ethoxide to paraffin in the process is 1:100, and the weight ratio of titanium tetrachloride to magnesium ethoxide is 20: 1. Adding a catalyst, a dispersant n-hexane and a cocatalyst alkyl aluminum into a polymerization reaction kettle, wherein the weight ratio of the catalyst to the dispersant n-hexane to the cocatalyst alkyl aluminum is 1:2 multiplied by 106150; when the temperature of the kettle rises to 50 ℃, introducing ethylene and comonomer 1-hexene (the volume ratio of the ethylene to the comonomer is 45:1), introducing hydrogen, controlling the reaction temperature at 80 ℃ and the reaction pressure atMaking the mixture under 0.6Mpa, reacting for 2 hours, cooling, discharging and drying to obtain polyethylene powder.
The polyethylene resin had a density of 0.950g/cm3Melt index (5kg) of 4.5g/10min and bulk density of 0.37g/cm3The powder particle size is larger than 80% of the total amount between 125-200 meshes.
97.5 percent (mass fraction) of high-density polyethylene powder, 1.5 percent (mass fraction) of antioxidant and 1 percent (mass fraction) of ultraviolet resistant agent are mixed in a high-speed mixer for 10min at normal temperature. The mixed material is processed by a rotational molding process, and the product is prepared by testing, wherein the ESCR is more than 1100 hours, and the elongation at break is more than 600%.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (11)

1. A preparation method of high-density polyethylene resin for rotational molding is characterized by comprising the following steps:
dispersing magnesium ethoxide in C6～C13Forming a pre-dispersion liquid in the straight-chain alkane, adding titanium tetrachloride into the pre-dispersion liquid, and reacting to obtain a catalyst;
placing the catalyst, the dispersing agent and the cocatalyst in a Hoechst slurry kettle type reactor, raising the temperature of the kettle to 48-52 ℃, introducing ethylene and alpha-olefin into the kettle, introducing hydrogen, and reacting at the reaction temperature of 80-86 ℃ and the pressure of 0.6-1.0 MPa to obtain polymer slurry;
and separating and drying the polymer slurry to obtain the high-density polyethylene resin for rotational molding.
2. The production method according to claim 1, wherein the α -olefin is 1-hexene and/or 1-octene.
3. The method according to claim 1, wherein the volume ratio of the ethylene to the hydrogen is 4.5 to 7.5:1, and the volume ratio of the ethylene to the α -olefin is 25 to 50: 1.
4. The method for preparing according to any one of claims 1 to 3, wherein C is6～C13The straight-chain alkane is one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, undecane and dodecane.
5. Preparation method according to any one of claims 1 to 3, characterized in that the dispersant is one or more of n-hexane, n-heptane, n-octane, n-nonane, n-decane, undecane, dodecane, preferably n-hexane, and the cocatalyst is an alkylaluminum AlRnX3-nWherein R is C1～C10X is halogen, preferably chlorine or bromine, 0 < n.ltoreq.3.
6. The method according to any one of claims 1 to 5, wherein the weight ratio of the catalyst, the dispersant and the co-catalyst is 1 (0.5 x 10)6～4×106):(100～500)。
7. The method of claim 6, wherein the step of preparing the catalyst comprises:
reacting said magnesium ethoxide and said C6～C13Mixing the straight-chain alkane, and performing pre-dispersion at a stirring speed of 100-1000 rpm and a temperature of 60-130 ℃ to obtain a pre-dispersion liquid;
cooling the pre-dispersion liquid to-20 to-10 ℃, then dripping the titanium tetrachloride into the pre-dispersion liquid, and reacting for 3-5 hours at a stirring speed of 100-1000 rpm to obtain a reaction liquid;
and filtering, washing and pre-activating the reaction solution to obtain the catalyst.
8. According toThe method of claim 7, wherein said magnesium ethoxide is reacted with said C6～C13The weight ratio of the straight-chain alkane is 1: 10-100, and the weight ratio of the titanium tetrachloride to the magnesium ethoxide is 130-20: 1.
9. The method according to any one of claims 1 to 3, wherein the reaction time of the ethylene, the α -olefin and the hydrogen is 1 to 3 hours.
10. A high-density polyethylene resin for rotational molding, which is prepared by the preparation method of any one of claims 1 to 9 and has a density of 0.944-0.950 g/cm3A melt index of 3 to 6g/10min and a bulk density of 0.36 to 0.40g/cm3The particle size of the powder is larger than 75% of the total amount and is 125-200 meshes.
11. A rotational molding method of polyethylene resin is characterized in that the high-density polyethylene resin for rotational molding of claim 10 is mixed with an antioxidant and an anti-ultraviolet agent, and a rotational molding processing is carried out to obtain a polyethylene resin rotational molding product, wherein the weight ratio of the high-density polyethylene resin to the antioxidant and the anti-ultraviolet agent is 1000 (2-20) to (1-10).
CN202010043595.4A 2020-01-15 2020-01-15 High-density polyethylene resin for rotational molding, and preparation method and application thereof Pending CN113121732A (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104098727A (en) * 2013-04-03 2014-10-15 中国石油天然气股份有限公司 High-density polyethylene resin and its preparation method and use
CN105985477A (en) * 2015-02-12 2016-10-05 中国石油天然气股份有限公司 Preparation method for catalyst used for production of high-density polyethylene resin
US20170210833A1 (en) * 2014-06-25 2017-07-27 Basell Polyolefine Gmbh Process for controlling an ethylene polymerization process

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104098727A (en) * 2013-04-03 2014-10-15 中国石油天然气股份有限公司 High-density polyethylene resin and its preparation method and use
US20170210833A1 (en) * 2014-06-25 2017-07-27 Basell Polyolefine Gmbh Process for controlling an ethylene polymerization process
CN105985477A (en) * 2015-02-12 2016-10-05 中国石油天然气股份有限公司 Preparation method for catalyst used for production of high-density polyethylene resin

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