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White polyolefin compositions having reduced die drool

a polyolefin composition and die drool technology, applied in the field of white polyolefin compositions, can solve the problems of unfavorable die lip build-up, surface roughness, localized surface defects, etc., and achieve the effect of improving the dispersion of carbon black and improving the resistance to thermo-oxidative degradation

Inactive Publication Date: 2005-11-17
EQUSR CHEM LP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides polyolefin compositions that have reduced die drool and lip build-up during extrusion processes. The improved compositions contain polyolefin resin, whitening / opacifying inorganic filler, and a mercaptobenzimidazole compound. The use of certain fillers, such as titanium dioxide and calcium carbonate, and the addition of processing aids and stabilizers, further enhance the performance of the compositions.

Problems solved by technology

The problems associated with the high-speed extrusion of filled polyolefins and subsequent forming operations are well documented.
The presence of inorganic fillers is also known to contribute to undesirable die lip build-up during extrusion / coextrusion of the film.
Die lip build-up can change the geometry of the die exit and cause surface roughness.
Also, the built-up material can periodically break free and cause localized surface defects.
If die drool is excessive it may require periodic shut down to clean dies and / or it may require operating at reduced line speeds.

Method used

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  • White polyolefin compositions having reduced die drool
  • White polyolefin compositions having reduced die drool
  • White polyolefin compositions having reduced die drool

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0046] A white composition suitable for extrusion coating and coextrusion was prepared in accordance with the invention. The composition was comprised as follows:

50%LDPE (MI 5.6 g / 10 min; density, 0.923 g / cm3)25%LDPE (MI 9 g / 10 min; density, 0.923 g / cm3)24.7%  TiO2 (Rutile; average particle size 0.2 microns)0.2% Aluminum Stearate (AlSt)0.1% Zinc 2-mercaptotolylimidazole (ZMTI)

[0047] The composition was prepared by letting down one part of a concentrate prepared as described above and containing 50% TiO2, 49.4% of the 9 MI LDPE, 0.4% AliSt and 0.2% ZMTI into one part of the 5.6 MI LDPE.

[0048] To evaluate die lip build-up the composition was then extruded at 235° C. using a Haake twin screw equipped with a 1½ inch slit die with 40 mil opening. The extruder was operated at 150 rpm. As the extrusion proceeded, the die lip was examined after one hour and at 30 minute intervals thereafter and the width of the amount of drool accumulated on the lip of the die measured. The amount of acc...

example 6

[0053] When a mercaptobenzimidazole compound is employed in conjunction with a hindered phenol compound, comparable reductions in die drool are possible. For example, using 0.2% of a mixture comprised of equal parts of ZMTI and Irganox 1010 in a concentrate containing 50% LDPE, 49.3% TiO2 and 0.3% AlSt gives results comparable to those of Examples 3 and 4.

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Abstract

Filled polyolefin compositions suitable for use in extrusion / coextrusion processes which reduce die drool are provided. More particularly, the compositions are white or opaque compositions comprising a polyolefin, whitening or opacifying inorganic filler and a mercaptobenzimidazole compound.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention relates to white polyolefin compositions useful in extrusion processes which exhibit reduced die lip build-up during extrusion. More particularly, the compositions contain a polyolefin, a whitening or opacifying filler and a die drool-reducing amount of mercaptobenzimidazole compound [0003] 2. Brief Description of the Prior Art [0004] Inorganic fillers are commonly incorporated in polyolefin resins for a variety of purposes. For example, inorganic fillers may be employed to reduce cost, impart flame retardancy, improve modulus or toughness, impart opacity, impart printability / writeability, impart ultraviolet (UV) resistance and the like. The amount and type of polyolefin used and inorganic filler incorporated can vary widely depending on the intended end-use application. [0005] Whitening or opacifying inorganic fillers, such as titanium dioxide and calcium carbonate, are widely used in the production o...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08K5/37C08K5/378C08L23/04C08L23/06C08L23/10
CPCC08K5/378C08L23/04C08L23/06C08L23/10C08L2205/02C08L23/02C08L81/00C08L2666/06
Inventor LEE, CHUN D.
Owner EQUSR CHEM LP