Method for producing shaped products from a plurality of paper layers arranged one above another
A method for producing shaped products from multi-layer paper dispenses with subsequent drying steps and still allows entirely compostable shaped products to be produced that, in terms of their shape, are not limited to flat angles between flat regions. A corresponding shaped product made of paper and to a device for carrying out the method are disclosed.
1 . A method for producing shaped products from a plurality of paper layers, comprising:
i) feeding the plurality of paper layers arranged one above another between a positive mold and a complementary negative mold of a pressing tool with pressing surfaces, each of the paper layers having a plurality of free fiber ends on its surface;
ii) aligning the free fiber ends transversely to top and bottom sides of the paper layers by suctioning off or feeding a gas or gas mixture, wherein a flow direction of the gas or gas mixture corresponds to a desired alignment; and
iii) pressing the paper layers to form a shaped product corresponding to the positive mold and the complementary negative mold by the pressing tool.
2 . The method according to claim 1 ,
wherein at least one pressing surface is gas-permeable or perforated at least in some regions and the suctioning off or feeding according to step ii) takes place through at least one pressing surface.
3 . The method according to claim 1 ,
wherein the multi-layer paper is a creped, cellulose-containing tissue paper, which is stretchable by 20% or more at least in partial regions.
4 . The method according to claim 1 ,
wherein the suctioning off of the gas or gas mixture in step ii) creates a negative pressure relative to an ambient pressure between the positive mold and the complementary negative mold.
5 . The method according to claim 1 ,
wherein the paper layers have a solvent or solvent mixture at least in step ii).
6 . The method according to claim 5 ,
wherein suctioning off of the gas or gas mixture in step ii) creates a reduced pressure that increases evaporation of the solvent or solvent mixture relative to ambient conditions.
7 . The method according to claim 5 ,
wherein a content of the solvent or solvent mixture in steps ii) and iii) is reduced to less than 5% of an initial content or, if the solvent is water, to a moisture content of the shaped product which is less than or equal to a moisture equilibrium between the shaped product and ambient air at 20° C., 50% relative humidity and 1000 hPa ambient air pressure.
8 . The method according to claim 5 ,
wherein at least two of the paper layers are spaced apart from one another during the feeding according to step i).
9 . The method according to claim 8 ,
wherein the solvent or solvent mixture is nebulized, evaporated, or nebulized and evaporated between the paper layers spaced apart from one another during the feeding of the paper layers according to step i).
10 . The method according to claim 1 ,
wherein a pressure during pressing according to step iii) is at least 100 kg/cm 2 .
11 . The method according to claim 1 ,
wherein a temperature of the pressing tool in step iii) is 100° C. to 350° C.
12 . The method according to claim 1 ,
wherein a composition of the multi-layer paper is free of elastomer additives and the shaped product is completely compostable.