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.
Claims20
A method for manufacturing a sandwich structure, which sandwich structure comprises 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 thus obtained;
- wherein said heating step a) and cooling step b) are carried out under pressure thereby preventing foaming of the at least one layer of the first thermoplastic
- d) during further advancing of the intermediate structure and at a temperature above the melting temperature or melting range of the first thermoplastic foaming of the at least one layer of thermoplastic comprising the decomposed chemical blowing agent of the intermediate structure, wherein the volume of the intermediate structure is made to increase and then kept constant thereby obtaining the sandwich structure, which 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 thus obtained.
(canceled)
A Device for continuously manufacturing a thermoplastic sandwich structure, which structure comprises at least one foam layer of a first thermoplastic and two cover layers which device comprises:
- a first endless belt and a second endless belt both driven by a drive and that are adapted for advancing under pressure the thermoplastic sandwich structure, an intermediate structure and/or starting structure thereof between the belts, which belts are mutually spaced apart at a first predetermined distance (d1) in a feed section, wherein the feed section is provided with heating means for heating the starting structure as well as cooling means for cooling the intermediate structure positioned downstream of the heating means, wherein in a transition section the distance between the first and second endless belts increases from the first predetermined distance (d1) to a second fixed distance (d2) greater than said first predetermined distance, optionally the transition section comprising heating means and/or cooling means for maintaining the intermediate structure at the required foaming temperature, and in a discharge section the first and second belts are maintained at the second fixed distance (d2), and the discharge section comprises cooling means for cooling the thermoplastic sandwich structure.
Dependencies are inferred from the claim text.