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Thin foamed polyethylene sheets and manufacture method thereof

A thin sheet, sheet technology, applied in the field of manufacturing these foam sheets, to achieve the effect of increasing the cushioning performance

Active Publication Date: 2008-12-17
DOW GLOBAL TECH LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] Therefore, methods of increasing MD tear strength traditionally used for conventional films (typically such as using low melt index LLDPE resins or using neat LLDPE resins or blends of rich LLDPE resins) are not necessarily applicable to foamed films and have therefore been used. No foam sheet is known to have sufficient tear strength, especially MD tear strength, in thicknesses from 1 to 10 mils

Method used

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  • Thin foamed polyethylene sheets and manufacture method thereof
  • Thin foamed polyethylene sheets and manufacture method thereof
  • Thin foamed polyethylene sheets and manufacture method thereof

Examples

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Embodiment

[0039] Sheets were formed from the LDPE and LLDPE resins shown in Table I. Resin A is an LDPE with a melt index (MI) (at 190°C / 2.16 kg) of 2.3 and a density of 0.920. Resin B is an LDPE with a MI of 0.47 g / 10 min and a density of 0.920. Resin C is LLDPE with a MI of 0.5 and a density of 0.920. Resin D is LLDPE with a MI of 1.0 and a density of 0.920. Resin E is LLDPE with a MI of 2.3 and a density of 0.917. Resin F is a ULDPE with a MI of 4 and a density of 0.904 g / cc. The chemical blowing agent or CBA used was SAFOAM FPE-50 containing 50% encapsulated sodium salt active ingredients of carbonic and polycarboxylic acids in a polyethylene carrier. A 3 mil thick film was made using a 2.5 inch extruder equipped with an 8 inch low pressure die and a medium shear barrier screw. A 40 mil lip with a 1 / 2 inch land length was used. The route runs at 220lbs.hr. MD tear strength was then measured according to ASTM D 1922 Elmendorf type B method. Puncture Propogation Tear (PPT) was...

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Abstract

The present invention relates to the use of particular blends of LLDPE and LDPE together with specific fabrication conditions to make foamed sheets of thin gauge with MD tear properties similar to an equivalent gauge non-foamed sheet of the same composition. In particular, blends which combine a high MI LLDPE rich fraction with a low MI branched LDPE minor fraction provide the adequate balance ofmechanical strength of the polymer base with its melt strength, extensibility and stress relaxation, allowing a thin foam film with MD tear strength which is comparable to non foamed counterparts of similar gauge and composition. The foamed films of the present invention are thin (generally from about I to 10 mils thick), and have an MD tear strength of at least about 160 grams for a 3 mil film as measured by ASTM D 1922. The foamed films of the present invention are preferably made at least in part from blends which comprise from 10 to 95 percent by weight of LLDPE having a relatively high (1.5 to 6) MI and from 5 to 90 percent of an LDPE resin having a relatively low MI (0.5 to 2.0).

Description

[0001] This application is a divisional application of Chinese Patent Application No. 200480019370.4 with an international filing date of June 30, 2004, an international application number of PCT / US2004 / 021173, and a title of "thin foamed polyethylene sheet". technical field [0002] The present invention relates to thin foamed polyethylene sheets, especially those having a thickness of 1 to 10 mils. These sheets have comparable MD tear strengths to non-foamed sheets of the same thickness and composition. The invention also relates to methods of making these foam sheets. Background technique [0003] The thin sheet or film of the present invention can be used in many applications, especially for blown film applications, including consumer trash bags, grocery bags, produce bags, pallet bags, etc. wrap), food wrap, liner, heavy duty bag, industrial bag, consumer bag, shrink film, label, FFS packaging Pouches for FFS packaging, tapes, stand-up pouches, lamination films, prote...

Claims

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Application Information

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IPC IPC(8): C08J9/04C08L23/06C08J9/00
CPCC08J9/0061C08J2323/06C08J2423/00C08J5/18C08J2323/08Y10T428/1376C08J9/00
Inventor F·马丁内斯
Owner DOW GLOBAL TECH LLC
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