Method for making foamed synthetic boards
AssigneeNmc S.A.
InventorsVincent Navez, David Brull, Robert Frere, Emmanuel Noël, Denis Job, Jean-Pierre Mayeres
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Abstract
The invention relates to a method for making articles having a veined aspect that includes the steps of (a) extruding a layer of substantially transparent PMMA including pigmented granules in a first extruder, (b) extruding a polystyrene layer including a foaming agent in a second extruder, wherein the extrusions of steps (a) and (b) are carried out simultaneously as a co-extrusion.
Claims17
A method for making articles having a veined aspect that comprises the steps of
- (a) extruding in a first extruder a layer of transparent PMMA comprising pigmented granules,
- (b) extruding in a second extruder a polystyrene layer comprising a foaming agent,
- wherein the extrusions of steps (a) and (b) are carried out simultaneously by co-extrusion, wherein the temperature in the melt of the PMMA in the first extruder is greater by at least 40° C. than the temperature in the melt of polystyrene in the second extruder and wherein the difference of the temperatures in the extrusion head of each of the first and second extruders is less than 10° C.
The method according to claim ,1 wherein the pigmented granules have a melt index (melt flow index according to ASTM D1238, MFI) of less than 0.7 g/10 min, 230° C., 3.8 kg.
An article comprising a layer of PMMA exhibiting pigmented striations forming a veined aspect, the layer of PMMA being co-extruded on a layer of foamed polystyrene.
The article according to claim 14, wherein the density of the foamed polystyrene is between 40 and 550 kg/m3.
Dependencies are inferred from the claim text.