Stock material or miscellaneous articles – Sheet including cover or casing – Foamed or expanded material encased
Patent
1997-03-05
1999-06-08
Copenheaver, Blaine R.
Stock material or miscellaneous articles
Sheet including cover or casing
Foamed or expanded material encased
156 78, 156163, 15624419, 15624427, 264 461, 264 464, 264 465, 4283184, 4283191, B32B 526, B32B 906, B32B 3108, G09F 900
Patent
active
059103507
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a biodegradable sandwich panel which is based on starch foam and a process for preparing the same.
2. Description of the Related Art
Composite materials or composite panels, as the case may be, which have a core coated with polyurethane foam or polystyrene foam are known. The disposal of such plastics is difficult since they virtually do not rot and can only be recycled after sorting.
DE-A-42 28 779 discloses a laminated composite material the layers of which consist of hardened starch foam and an additional layer material. The process for preparing the starch foam and the laminated composite material is a multi-step process. Moreover, the starch foam has to be cured in order to effect the bonding to the additional layer material. WO 92/16584 relates to a biodegradable polymer compound on the basis of destructurized starch with synthetic additives for the preparation of molded articles by means of common process techniques.
It is an object of the invention to provide a biodegradable sandwich panel characterized by multiple applications and a simple and cost-efficient preparation process.
SUMMARY OF THE INVENTION
This object is achieved by the features of the claims.
In achieving the object, the invention is based on the concept of providing a sandwich material having a biodegradable cover material made of paper and/or paperboard and/or a sheeting and a core made of extruded starch foam, which sandwich material is prepared in a continuous process wherein a starch foam is prepared in an extrusion process, introduced in situ between paper or cardboard webs and/or sheeting, pressed in a continuously operating roller press and processed. The number of paper and starch foam layers is arbitrary. If the sandwich material obtained with this process has a cross-section below 20 mm and a soft, flexible setting of the starch foam, it is prepared as an endless material wound on a roll. With a hard setting of the starch foam and/or cross-sections being greater than 20 mm, the sandwich panels are cut to a desired size after pressing.
Depending on the demand profile of the sandwich material, the specific weight of the starch foam core can be 10 to 250 kg/m.sup.3 and the weight per unit area of the paper and/or cardboard and/or sheeting cover layers can be 10 to 800 g/m.sup.2. The sandwich panels provided by the present invention fulfil the same application purpose as a packaging material, as a construction material for low temperature, heat or sound insulation, as protection during transport and against shock, as a display and carrier for placards, posters, pictures and imprints, and they are recyclable in the paper-making cycle.
The advantages of the sandwich panels according to the present invention reside above all also in a simple preparation process in which all process steps take place continuously without intermediate steps and which can easily be changed so that, if required, a respectively shaped rigid or resilient sandwich panel can be prepared immediately, which exhibits, for example, a desired heat or low temperature insulation or also shock absorption properties.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, the invention is explained in more detail in connection with the drawings in which:
FIG. 1: is the method principle for the preparation of sandwich panels according to the present invention,
FIG. 2: is a view onto the extruder arrangement extruding an all-over starch foam core,
FIG. 3: is a view onto the extruder arrangement extruding rod-like starch foam strands as a core for the sandwich panel according to the present invention, and
FIG. 4: is a view onto the extruder arrangement extruding starch foam strands winding like a snake as a core for the sandwich panel according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to a preferred embodiment of the invention, a sandwich panel according to the present invention consists of a starch foam core 1, the upper and lower surfaces thereo
REFERENCES:
patent: 4613627 (1986-09-01), Sherman et al.
patent: 4755408 (1988-07-01), Noel
patent: 4863655 (1989-09-01), Lacourse et al.
DE 4317697 (english abstact), Dec. 1994.
DE 4228779 (english abstract), Mar. 1994.
English Translation of DE 42 28 779, Mar. 1994.
English Translation of WO 94/05492, Mar. 1994.
Loracks Juergen
Pommeranz Winfried
Schmidt Harald
Bio-Tec Biologische Naturverpackugen GmbH
Copenheaver Blaine R.
Spencer George H.
Wells Ashley J.
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