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Multi-wall sheet without the triangle effect, coated by coextrusion

Inactive Publication Date: 2011-01-13
BAYER MATERIALSCIENCE AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The process produces coextruded multi-wall sheets with a smooth, uniform surface, avoiding the triangle effect and reducing material wastage, while allowing for the production of sheets with UV protection and functional layers like IR reflection, offering advantages over lacquering in terms of solvent use and equipment requirements.

Problems solved by technology

However, all the coextruded multi-wall sheets known from the state of the art exhibit the so-called “triangle effect”, a defect resulting upon the coextrusion, described as a combination of gussets consisting of the material making up the coextruded layer with unevenness of the surface of the sheet (FIG. 1).

Method used

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  • Multi-wall sheet without the triangle effect, coated by coextrusion
  • Multi-wall sheet without the triangle effect, coated by coextrusion
  • Multi-wall sheet without the triangle effect, coated by coextrusion

Examples

Experimental program
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Embodiment Construction

[0015]Given the state of the art, the objective is therefore to produce a coextruded multi-wall sheet which, in contrast to the state of the art, no longer exhibits the triangle effect.

[0016]This object forms the basis of the present invention.

[0017]In the case of sheets coated on one side, this problem may be solved with a modified feed of the coextrusion material by increasing the material feed from the non-coextruded side, making it possible to avoid gusset formation on the coextruded side (FIG. 2).

[0018]In the case of sheets coextruded on both sides, however, this process is inapplicable. Here, the increased feed from one side would produce a thicker gusset on the other side, so the gain on one side would be offset by a loss on the other side (FIG. 3).

[0019]It has now been found, surprisingly, that the gusset formation on each side may be virtually completely avoided by modifying the material flows during extrusion in such a way that a partial flow is tapped from the conventiona...

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Abstract

Gussetless multi-wall sheets are prepared using a coextrusion process which entails feeding part of the base material directly into and via the male insert of the extrusion die thereby producing the gussetless sheet.

Description

FIELD OF THE INVENTION[0001]The present invention relates to extrusions and in particular to extrusion of thermoplastic materials.SUMMARY OF THE INVENTION[0002]A process for the production of coextruded gussetless multi-wall sheets is disclosed. Also disclosed is an extrusion die for the production of such sheets. The inventive coextrusion process entails feeding part of the base material directly into the male insert of the multi-wall extrusion die to produce a gussetless sheet.BACKGROUND OF THE INVENTION[0003]Multi-wall sheets are often provided where one or both of the outer coextruded walls are capable of performing any of a variety of functions. For example, one or both outside walls may provide UV protection for the sheet against damage (e.g. yellowing) by UV radiation, but other functions, e.g. IR reflection, are also performed in this way.[0004]The state of the art relating to multi-layer products is summarized below.[0005]EP-A 0 110 221 discloses sheets consisting of two la...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B3/30C08G64/00B29C48/08B29C48/305B29C48/32B29C48/50
CPCB29C47/0004Y10T428/24562B29C47/0021B29C47/0028B29C47/0054B29C47/065B29C47/12B29C47/145B29C47/705B29K2033/12B29K2067/00B29K2069/00B29K2105/0032B29K2105/0044B29K2105/005B29K2995/0025B29K2995/0026B29K2995/0029B29L2031/60B29C47/0019B29C48/022B29C48/07B29C48/08B29C48/11B29C48/0017B29C48/21B29C48/307B29C48/705Y10T428/31855B29C48/30B29C48/18
Inventor RUBECK, JAKOB
Owner BAYER MATERIALSCIENCE AG