Method and device for manufacturing a sandwich structure comprising a thermoplastic foam layer
AssigneeFits Holding B.V.
InventorMartin Theodoor De Groot
Life of this patent
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Abstract
A method and device for manufacturing a sandwich structure comprising at least one foam layer of a first thermoplastic comprising a chemical blowing agent and two cover layers. The decomposition temperature of the chemical blowing agent is higher than the melting point or range of the first thermoplastic. The method comprises a series of steps performed on an advancing starting structure including heating under pressure in order to cause decomposition of the blowing agent, intermediate cooling, foaming at a constant volume and further cooling.
Claims19
A method for manufacturing a sandwich structure, the sandwich structure comprising at least one foam layer of a first thermoplastic and two cover layers, the method comprising the steps of:
- a) providing an advancing starting structure comprising at least one layer of a first thermoplastic having a melting temperature or melting range, and two cover layers;
- wherein the at least one layer of the first thermoplastic comprises a chemical blowing agent having a decomposition temperature above the melting temperature or melting range of the first thermoplastic;
- b) heating the advancing starting structure to a temperature above the decomposition temperature of the chemical blowing agent so that decomposition of the chemical blowing agent occurs, thereby obtaining an advancing intermediate structure wherein the decomposed chemical blowing agent is present in the at least one layer of the first thermoplastic;
- c) subsequent to the decomposition of the chemical blowing agent, cooling of the advancing intermediate structure;
- wherein said heating step b) and cooling step c) are carried out under pressure while the advancing starting structure and the advancing intermediate structure are advanced in a press having press tools thereby preventing foaming of the at least one layer of the first thermoplastic
- d) during further advancing of the intermediate structure the at least one layer of thermoplastic comprising the decomposed chemical blowing agent of the intermediate structure is foamed at a temperature above the melting temperature or melting range of the first thermoplastic, wherein the volume of the intermediate structure is made to increase by increasing the distance between the press tools of the press and then kept constant thereby obtaining the sandwich structure, wherein the sandwich structure comprises the at least one foam layer of the first thermoplastic and the two cover layers;
- and
- e) cooling of the advancing sandwich structure under pressure.
Dependencies are inferred from the claim text.