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Low-temperature-suitable polyethylene and injection moulding composition

A polyethylene and low-temperature technology, applied in the field of low-density polyethylene injection molding, can solve the problems of limiting the application field of polyethylene resin, uneven distribution of lamella thickness, poor toughness and crystallization ability, etc., and achieves good direct application effect and good comprehensive mechanics performance effect

Active Publication Date: 2016-01-27
CHINA PETROLEUM & CHEM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Polyethylene is easy to deform and warp
And because the low-temperature toughness of polyethylene injection molding products is poor, polyethylene products need to add various low-temperature modifiers and / or impact modifiers before they can be used in low-temperature environments, which will undoubtedly increase production costs and increase process difficulty
Seriously limit the application field of polyethylene resin
[0004] The inventors of the present invention have found that the poor low temperature toughness of polyethylene injection molding products is mainly due to the high crystallization ability of polyethylene, the uneven distribution of platelet thickness of traditional polyethylene, and the excessive concentration of components at specific melting points in polyethylene, which leads to The impact resistance of polyethylene products is low at low temperature, and the product may be damaged if it is used in a low temperature environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Catalyst configuration: add 170g of activated silica gel carrier under nitrogen atmosphere, then add 600g of 10% methylalumoxane (MAO) in toluene solution, add 5g of bis(2-butyl-4-phenylfluorenyl) zirconium chloride ·2LiCl·THF toluene solution, after reacting for 1.2 hours, filter, wash and dry.

[0030] For gas phase polymerization, the polymerization temperature is 85°C, the polymerization pressure is 2.1MPa, the ethylene partial pressure is 80%, the hydrogen concentration is 900ppm, and the ratio of 1-hexene to ethylene is 0.025:1.

[0031] Gained polyethylene resin melt mass flow rate is 40g / 10mim, density 0.918g / cm 3 , The range of melting temperature of polyethylene resin measured by differential scanning calorimeter is 120°C, and the degree of branching is 0.7.

[0032] The composition in parts by weight consists of: 100 parts of polyethylene resin, 0.02 parts of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, tris(2,4-di-tert-b...

Embodiment 2

[0034] Catalyst configuration is the same as embodiment 1.

[0035] For gas phase polymerization, the polymerization temperature is 85°C, the polymerization pressure is 2.05MPa, the ethylene partial pressure is 85%, the hydrogen concentration is 950ppm, and the ratio of hexene to ethylene is 0.028.

[0036] Gained polyethylene resin melt mass flow rate is 65g / 10mim, density 0.919g / cm 3 . The range of melting temperature of polyethylene resin measured by differential scanning calorimeter is 125°C, and the degree of branching is 1.1.

[0037] The composition in parts by weight consists of: 100 parts of polyethylene resin, 0.05 part of n-octadecyl propionate, 0.05 part of n-octadecyl alcohol ester of β-(3,5-di-tert-butyl-4-hydroxyphenyl), 0.05 part of tris(2,4-di-tert- Butylphenyl) phosphite 0.05 parts, magnesium stearate 0.08 parts.

Embodiment 3

[0039] Catalyst configuration is the same as embodiment 1.

[0040] The polymerization temperature is 87°C, the polymerization pressure is 2.2MPa, the ethylene partial pressure is 90%, the hydrogen concentration is 1100ppm, and the ratio of hexene to ethylene is 0.020:1.

[0041] Gained polyethylene resin melt mass flow rate is 1600g / 10mim, density 0.915g / cm 3 , The range of melting temperature of polyethylene resin measured by differential scanning calorimetry is 110°C, and the degree of branching is 0.1.

[0042] The composition in parts by weight consists of: 100 parts of polyethylene resin, 0.06 parts of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester, tris(2,4-di-tert-butyl 0.06 part of phenyl) phosphite, 0.05 part of zinc stearate.

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Abstract

The present invention discloses a low-temperature-suitable polyethylene and an injection moulding composition, belongs to the technical field of low density polyethylene injection moulding; and are characterized in that: the polymerization temperature of the polymerization system is controlled at 83-87 DEG C, the polymerization pressure is controlled at 2.0-2.2MPa, the ethylene partial pressure is controlled at 75 to 90%, the hydrogen concentration in the polymerization system is 800-1200ppm, a supported metallocene catalyst is used to obtain linear low density polyethylene, wherein the polyethylene melt mass flow rate is 30-160g / 10min, the density is 0.915-0.922g / cm<3>, lamellar thickness is 4.109 angstrom-12.147 angstrom, and crystalline fraction content distribution is uniformly dispersed; and an appropriate amount of antioxidants and acid scavengers are added into the polyethylene to obtain the injection moulding composition. By controlling the polymerization temperature, pressure and other reaction conditions, the polyethylene lamellar thickness and component content are controlled; and the injection moulding composition has higher resistance to low temperature impact without addition of a variety of low-temperature anti-impact modifiers.

Description

technical field [0001] The invention relates to low-temperature applicable polyethylene and its injection molding composition, belonging to the technical field of injection molding of low-density polyethylene. Background technique [0002] Plastic injection molding is to inject molten plastic into the mold of plastic products under pressure, and cool it to form various plastic parts. As a crystalline raw material, polyethylene has very little hygroscopicity, no more than 0.01%, and does not need to be dried before processing. Polyethylene has good molecular chain flexibility, small inter-bond force, low melt viscosity, and excellent fluidity, so thin-walled long-process products can be formed without too much pressure during molding. [0003] Because the shrinkage range of polyethylene is large, the shrinkage value is large, and the directionality is obvious, the shrinkage rate of low-density polyethylene is about 1.22%, and the shrinkage rate of high-density polyethylene i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F210/02C08F4/6592C08L23/08C08K5/134C08K5/526C08K5/098
Inventor 郭锐王常宝王群涛王日辉许平高凌雁石晶
Owner CHINA PETROLEUM & CHEM CORP
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