US 6,053,214 AGranted

Oriented polymeric products

AssigneeUponor N.V.

InventorsMichael Borje Sjoberg, Jan Rolf Rydberg, Nils Yngve Lundequist, Lars Goran Hoving, Hans Martin Tony Josefsson, Stig Lennart Agren, Bjorn Axel Roland Olsson, Jyri Jaakko Jarvenkyla

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Abstract

A continuous method of extruding an oriented plastic article of improved strength. A chemically reactive polymer, monomer or other compound is included in the matrix material(s) and a (multilayer) parison is extruded or melt formed having built-in thermoplastic orientation caused by shear or caused by elongational flow. A reaction can be activated in the molten state thereof by additional heat resulting in a cross-linked structure or at least the mobility of the molecules being reduced, resulting in a longer relaxation time which makes the freezing of permanent orientation possible. The soft matrix can be stretched while still hot in the hoop and/or axial direction. Then, the product thus obtain is calibrated and cooled in an oriented state.

Claims84

Dependent claims

A method of forming and continuously orienting an article comprising a crystalline or semi-crystalline thermoplastic polymeric material(s) at a temperature greater than the crystalline melting temperature of raid material(s), which comprises the steps of:

adding a chemically reactive substance(s) to the polymeric material before or during forming of either the entire article, or to one or more layers of a multilayer article, or to axial or helical stripes of the article, or to certain segments of the article in the axial direction;
plasticizing and forming a parison of the polymeric material(s) thus prepared at a temperature not high enough to activate the reaction of the said reactive substance(s);
optionally, inducing shear at least to the layer(s) where the chemically reactive substance(s) have been added to and/or stretching the still soft parison in one or both of two directions, simultaneously or stepwise, said stretching including axial draw to effect thermoplastic orientation of the material in the longitudinal direction of the parison and/or radial expansion to effect thermoplastic orientation of the material in the hoop direction of the parison;
decreasing the mobility of the molecules in the layer(s) to be oriented by activating a chemical reaction between the chemically reactive substance(s) and the polymeric material(s) having the chemically reactive substance(s) added thereto when the polymeric material(s) still is/are in a molten state;
inducing shear at least to the product, layer(s), stripes, or segments to which the chemically reactive substance(s) have been added and/or stretching the still soft, at least partly reacted parison in two directions, simultaneously or stepwise, said stretching comprising axial draw to effect orientation of the material in the longitudinal direction of the parison and radial draw to effect orientation of the material in the transverse direction of the parison;
calibrating and cooling the parison in the oriented condition to make the orientation permanent at least in the layer(s) where the chemical reaction(s) has taken place.

3 more elements

An extrusion apparatus for producing an oriented extruders of polymeric material, comprising;

a) a plasticating extruder means for providing a melt(s) or partial melt(s) of said polymeric(s) material(s) and a chemically reactive substance and feeding said melt under pressure through a discharge opening in said extruder means;
b) an elongational flow pattern-developing cavity means having an inlet opening communicating with said discharge opening of said extruder means, a flow cavity, and a discharge orifice, the relative geometries of said flow cavity and said discharge orifice being such as to develop within the molten polymer material flowing from said extruder means through said cavity means an elongational flow pattern which induces molecular orientation at least transversely to the direction of flow within said molten polymeric material;
c) an orientation-retaining extrusion die means provided with an orifice extending therethrough, said die orifice having an inlet end and outlet end, said discharge orifice of said cavity means opening into said inlet end of said die orifice so as to permit flow of the oriented molten polymeric material from said cavity means into said die means, said discharge orifice having a cross-sectional area in the range of from 0.9 to 2.0 times the cross sectional area of said die orifice;
d) temperature control means for maintaining the temperature of said flowing molten polymeric material below the reaction temperature of the said chemically reactive substance in the extruder and in at least a first part of said cavity means, and for maintaining the temperature of said flowing molten polymeric material above said reaction temperature in at least a second part of said cavity means and/or said inlet end of said die orifice;
e) optionally, temperature control means for maintaining in said dip orifice an axial temperature gradient descending in the direction of flow through a median die temperature substantially equal to the normal melting point of said polymeric material so that solidification of said polymeric material will be inhibited in the entrance region of said die means and may be initiated within said die means;
and
f) optionally, a variable spend take-up means for withdrawing an extrudate of said polymeric material from said outlet end of said die orifice at a controlled draw rate;
the arrangement being such that said extrudate begins to solidify within said die means or after exiting from said outlet end of said die orifice but before any substantial radial swelling of said extradite can occur.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/043,639Filed 28 Jul 1998
Priority: SE 950327220 Sep 1995
Granted: 25 Apr 2000
Term ends: Not estimatedThe source records don’t support an estimate.

Classification72 codes

F16L 9/147
Compound tubes, i.e. made of materials not wholly covered by any one of the preceding groups: comprising only layers of metal and plastics with or…
B29C 44/22
For articles of indefinite length: consisting of at least two parts of chemically or physically different materials, e.g. having different densities
B29C 48/08
Flat, e.g. panels: flexible, e.g. films
B29C 48/09
Characterised by the shape of the extruded material at extrusion: articles with cross-sections having partially or fully enclosed cavities, e.g.…