Method and apparatus for producing solid foam, product and use
The application relates to a method and apparatus for producing a solid foam continuously. A homogeneous suspension is formed from a raw material in which the suspension comprises a solidifying agent, and a foam mixture which comprises bubbles is formed by mixing air bubbles into the suspension. The foam mixture is injected via at least one nozzle to form a foam pattern and the foam pattern is laid on a moving surface and the foam mixture of the foam pattern is solidified in order to form a solid foam such that the bubbles of the foam mixture shrink in off-length directions to form the shaped bubbles. Further, the application relates to the product and the use of the method.
1 . A method for producing a solid foam continuously, in which a homogenous suspension is formed from a raw material, air is added to the homogenous suspension to form a foam mixture, and the solid foam is formed from the foam mixture, wherein the method comprises:
forming the homogeneous suspension from a bio-based raw material comprising fibers in which the homogenous suspension comprises a solidifying agent;
adding a chemical which lowers surface tension and increases viscosity to the homogenous suspension and which is selected from methylcellulose, derivate of the methylcellulose, carboxymethyl cellulose, hydroxypropyl cellulose, ethyl cellulose, or one of their combinations;
forming the foam mixture which comprises bubbles by mixing air bubbles into the homogenous suspension; and
treating the foam mixture by an extruder and injecting the foam mixture from the extruder to a moving surface via at least one nozzle to form a foam pattern which comprises parallel foam stripes to create a rod-shaped structure and laying the foam pattern on the moving surface and solidifying the foam mixture of the foam pattern using heat in order to form the solid foam having anisotropic properties and comprising bubbles such that the bubbles of the foam mixture shrink in off-length directions to form elongated bubbles in the solid foam.
2 . The method according to claim 1 , wherein the chemical is a photopolymer.
3 . The method according to claim 1 , wherein a solid fibre material is added to the raw material and/or the homogenous suspension, and the solid fibre material is selected from the group consisting of carbon fibers, carbon nanotubes, graphene, carbon mesh, laponite, hemp, expanded polystyrene, polystyrene, polymer, polymer sticks, yarn and their combinations.
4 . The method according to any one of claim 1 , wherein the bio-based raw material is selected from the group consisting of biomass, bio-based residue material, wood, wood-based material, forest-based material, cellulose, treated bio-based material, untreated bio-based material, or their combinations.
5 . The method according to claim 1 , wherein the foam mixture is solidified by heat, photocatalytes, crosslinking, freezing or their combinations.
6 . The method according to claim 1 , wherein the foam mixture is solidified at temperature of 1-90° C.
7 . The method according to claim 1 , wherein a product is formed from one or more foam patterns.
8 . A solid foam product obtained by the method according to claim 1 , wherein the solid foam comprises a foam mixture comprising a solidifying agent.
9 . The solid foam product according to claim 8 , wherein the solid foam product comprises at least two foam patterns arranged one on top of the other to form a layered structure, and each foam pattern is arranged in a desired direction on top of one another in the layered structure.