STRUCTURED BODY AND METHOD FOR ITS PREPARATION

1 . Structured body (K) prepared from at least one powdery starting material by application of heat and/or pressure and comprising several layers, wherein

the starting material consists predominantly of a thermoplastic basic material,

the density of at least two of the several layers ( 1 , 2 , 1 a , 2 a , 3 , 4 , 5 , 6 , 7 ) of the structured body (K) differ from each other,

at least one layer of lower density ( 2 ; 2 a ; 4 ; 6 ) contains hollow microspheres ( 9 ).

2 . Structured body (K) according to claim 1 ,

wherein

the hollow microspheres ( 9 ) are regularly or/and irregularly distributed in the respective layer ( 2 ; 2 a ; 4 ; 6 ).

3 . Structured body (K) according to claim 1 ,

wherein

the hollow microspheres permeate partially the interface (T 1 ; T 2 ; T 3 ; T 4 ; T 5 ; T 6 ; Tx; Tz) to the adjoined layer ( 1 ; 3 ; 5 ; 7 ) and/or the area close to the adjoined layer ( 1 ; 3 ; 5 ; 7 ).

4 . Structured body (K) according to claim 1 ,

wherein

the structured body (K) is sheet-like.

5 . Structured body (K) according to claim 1 ,

wherein

the layer or layers, which is/are located in the X-direction, i.e. viewed along the direction of its (K) smallest length extension, in the border area (X 1 , X 2 ) of the structured body (K), is/are a layer or layers of higher density ( 1 ; 1 a ; 7 ).

6 . Structured body (K) according to claim 1

wherein

the layers of different density ( 1 , 2 , 3 ; 1 , 2 , 1 ; 1 , 2 , 1 a ; 2 , 1 , 2 ; 2 , 1 , 2 a ; 2 , 3 , 4 ; 4 , 5 , 6 ; 5 , 6 , 7 ), when viewed along the X-direction, at least differ once from each other.

7 . Structured body (K) according to claim 1

wherein

at least two of the several layers have a different density.

8 . Structured body (K) according to claim 1

wherein

a support material ( 8 ) is located in at least one of the layers ( 1 , 2 , 1 a , 2 a , 3 , 4 , 5 , 6 , 7 ) or between two adjoining layers of these layers, wherein the support material ( 8 ) consists of fibers, or of a web, or of a laid web, or of a fleece, or of a combination of these just specified materials.

9 . Structured body (K) according to claim 1

wherein

in at least one layer of lower density ( 2 ; 2 a ; 4 ; 6 ), the hollow microspheres ( 9 ) are statistically distributed and arranged.

10 . Structured body (K) according to claim 1

wherein

the structured body (K) consists up to 90% of thermoplastics of one polymer type or one polymer group.

11 . Structured body (K) according to claim 10

wherein

the polymer type or the polymer group is PVC.

12 . Structured body (K) according to claim 1

wherein the density of adjoining layers differ from each other in at least 20%.

13 . Structured body (K) according to claim 1

wherein the transition area between adjoining layers, i.e. the interfaces (T 1 ; T 2 ; T 3 ; T 4 ; T 5 ; T 6 ; Tx; Tz), in particular between layers of different density, is formed of a joining layer, which is made up of particles/components of both of these layers, which in turn are mixed among each other and connected to each other in a form-fitted and/or substance-bounded manner.

14 . Thermoplastic structured body (K) according to claim 13 , wherein the thickness of the joining interface (T 1 ; T 2 ; T 3 ; T 4 ; T 5 ; T 6 ; Tx; Tz) is at least 5%, preferably 10% and not more than 30% of the thickness of the adjoining thicker layer.

15 . Method for production of a structured body (K) with the succeeding process steps:

spreading a layer ( 1 ) of a powdery thermoplastic material of a first type onto a supporting layer;

spreading of at least a further, second layer ( 2 ) of a powdery thermoplastic material of a second type or of a first type onto the first layer;

whereby the powdery thermoplastic material of at least one of the spread layers contains hollow microspheres;

consolidating the powdery layers and connecting adjoined layers by means of heating the materials and simultaneous expanding of the hollow microspheres, which are arranged territorially limited,

pressing to the intended overall thickness of the structured body (K) and

subsequent cooling down.

16 . Method according to claim 15 , comprising the following process steps

spreading a third layer ( 3 ) of a powdery thermoplastic material of a first type or of a second type or of a further modified type onto the second layer ( 2 ),

if need be, spreading further layers ( 4 ; 6 ; 7 ; 8 ) in the same sequence as for the first ( 1 ) and the second layer ( 29 );

consolidating the powdery layers and connecting adjoining layers by means of heating the materials and simultaneous expanding of the hollow microspheres, which are arranged territorially limited,

pressing to the intended overall thickness of the structured body (K) and

subsequent cooling down.

17 . Method according to claim 15 ,

wherein

the structured body (K) is produced in a continuous production process, i.e., on a conveyer belt, preferably on a double belt press.

18 . Method according to claim 15 ,

wherein

by means of controlled spreading, the penetrating depth of particles of the material, which is still to be spread, into the already spread material, is affected in order to form a joining face in the boundary area of adjoined layers, for instance by means of variation of the kinetic energy, for instance by means of variation of the dropping height of the material to be spread, whereby the dropping height may optionally be varied by means of the width of the structured body (K) to be produced.

19 . Method according to claim 15 ,

wherein

when spreading the layers, also fiber material is spread into one or several layers.

20 . Method according to claim 15 ,

wherein

into one of the layers or between two adjoined layers, a support material ( 8 ) is inserted, for instance a fiber sheet, a laid web, a web, or endless fibers.

21 . Method according to claim 15 ,

wherein

the outer surface of the structured body (K) is laminated with a further layer.