Polyethylene blends and films

A polyethylene and blend technology, applied in the field of polyethylene blends, can solve the problem of HDPE film not having impact and tearing properties

Inactive Publication Date: 2004-01-21
EQUSR CHEM LP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although HDPE films are more similar to the paper they have replaced in these industries, HDP...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Preparation of HMW MDPE

[0023] The catalyst was prepared according to U.S. Patent 4,464,518. The catalyst was dispersed in hexane to produce a catalyst slurry containing about 1.4% solids by weight. The catalyst slurry (0.059 parts per hour), triethyl aluminum co-catalyst (0.0033 parts per hour), hexane (41.0 parts per hour), 1-butene (0.37 parts per hour) and ethylene (per hour 16.9 parts per hour) was continuously added to the first reactor. The pressure of the reactor was controlled at about 140 psig, the temperature was 82° C., and the molar ratio of hydrogen to ethylene in the vapor space was about 3.8, so that the first polymer was prepared. MI of the first polymer 2 It is 220dg / min, and the density is 0.953g / cc.

[0024] The first polymer is transferred to a flash tank, where a part of the volatile material is removed. The mixture is then transferred to the second reactor. Hexane (42.9 parts per hour), 1-butene (1.23 parts per hour), and ethylene (18.6 parts per ho...

Embodiment 2

[0028] 35 / 65 (weight) blend of HMW MDPE and LLDPE

[0029] The HMW MDPE prepared in Example 1 was blended with commercially available LLDPE (PetrotheneSelect Super Hexene LLDPE, a product of Equistar Chemical Company) at a ratio of 35 / 65 (weight). MI of the LLDPE 2 It is 0.70dg / minute and the density is 0.918g / cc. The LLDPE and HMW MDPE resins are dry mixed and added to the extruder. MI of the blend 2 It is 0.30dg / min, and the density is 0.927g / cc. The resulting blend was converted into a film with a thickness of 1.0 mil on a 200 mm mold with a die gap of 1.5 mm. The film was prepared under the conditions of a blow-up ratio (BUR) of 4:1 and a stem height of six times the diameter of the mold. The modulus of the film is 52000 psi, the MD tear strength is 200 g, the TD tear strength is 425 g, and the dart drop is 915 g.

Embodiment 3

[0031] A 55 / 45 (weight) blend of HMW MDPE and LLDPE

[0032] Example 2 was repeated, but the ratio of HMW MDPE / LLDPE was 55 / 45 (weight). MI of the blend 2 It is 0.20dg / min and the density is 0.931g / cc. The modulus of the film is 62000 psi, the MD tear strength is 125 g, the TD tear strength is 350 g, and the dart is 690 g.

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Abstract

A blend comprising a high molecular weight, medium density polyethylene (HMW, MDPE) and a linear low density polyethylene (LLDPE) is disclosed. The blend comprises from about 20 wt % to about 80 wt % of HMW MDPE. The HMW MDPE has a density from about 0.92 to about 0.944 g/cc, a melt index MI2 from about 0.01 to about 0.5 dg/min, and a melt flow ratio MFR from about 50 to about 300. The blend also comprises about 20 wt % to about 80 wt % of LLDPE. The LLDPE has a density within the range of about 0.90 to about 0.925 g/cc and an MI2 within the range of about 0.50 to about 50 dg/min. The blend provides films with significantly improved toughness and tear strength compared to MDPE or HDPE, and high modulus compared to LLDPE.

Description

Invention field [0001] The present invention relates to polyethylene blends. The blend includes high molecular weight medium density polyethylene (HMW MDPE) and linear low density polyethylene (LLDPE). The invention also relates to a film prepared from the blend. Background of the invention [0002] Polyethylene is divided into high density polyethylene (HDPE, density 0.941g / cc or greater), medium density polyethylene polyethylene (MDPE, density 0.926 to 0.940g / cc), low density polyethylene (LDPE, density 0.910) To 0.925g / cc) and linear low-density polyethylene (LLDPE, with a density of 0.910 to 0.925g / cc). (See ASTM D4976-98: Standard Specification for Polyethylene Plastic Molding and Extrusion Materials (Standard Specification for Polyethylene Plastic Molding and Extrusion Materials)). One of the main uses of polyethylene (HDPE, LLDPE, and LDPE) is in film applications, such as grocery store bags, institutional and consumer can liners, commodity bags, multi-wall bag linings, an...

Claims

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Application Information

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IPC IPC(8): C08J5/18C08L23/04C08L23/06C08L23/08
CPCC08L23/0815C08L23/06C08L23/04C08L2205/02C08L2666/04C08L23/12C08J5/18C08L29/04
Inventor K·L·威廉姆斯L·V·克里布斯S·M·艾姆菲尔德V·善德拉舍卡
Owner EQUSR CHEM LP
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