Modified melamine-formaldehyde resin, a paper impregnated with a modified melamine-formaldehyde resin, a method for manufacturing a floor panel, and use of dicyandiamide as a modifier in a melamine-formaldehyde resin
A use of dicyandiamide is provided as a modifier in a melamine-formaldehyde resin for use in a floor panel including a substrate and a top layer. The top layer defines an upper surface of the floor panel. The floor panel is provided with embossments extending from the upper surface, such that the thickness of the floor panel varies along a cross-section of the floor panel. The top layer has a modified melamine-formaldehyde resin including formaldehyde and melamine in an F/M molar ratio within the range of from 1.60 to 1.80, and at least one modifier, thereby providing a floor panel having improved transparency at the embossments.
1 . A modified melamine-formaldehyde resin comprising formaldehyde and melamine, wherein the resin comprises dicyandiamide;
wherein a formaldehyde/melamine molar ratio is within a range of from 1.60 to 1.80, wherein an amount of dicyandiamide is within a range of from 30 to 40% by weight based on a total weight of melamine and dicyandiamide.
2 . The modified melamine-formaldehyde resin according to claim 1 , wherein the resin comprises polyol, in an amount within a range from 1 to 5%, by weight based on a total liquid weight of the resin.
3 . A paper impregnated with a modified melamine-formaldehyde resin, wherein the melamine-formaldehyde resin is a melamine-formaldehyde resin according to claim 1 .
4 . The paper impregnated with a modified melamine-formaldehyde resin according to claim 3 , wherein said paper is printed paper.
5 . A method for manufacturing a floor panel comprising a substrate and a top layer, said top layer defining an upper surface of said floor panel,
wherein said floor panel is provided with embossments extending from said upper surface, such that a thickness of the floor panel varies along a cross-section of said floor panel, wherein said method comprises the steps of:
a) providing said substrate;
b) providing said top layer, said top layer comprising a modified melamine-formaldehyde resin comprising formaldehyde and melamine in a formaldehyde/melamine molar ratio within a range of from 1.60 to 1.80, and at least one modifier,
wherein said at least one modifier is dicyandiamide, wherein an amount of dicyandiamide is within a range of from 30 to 40% by weight based on a total weight of melamine and dicyandiamide;
c) composing a stack which comprises said substrate and said top layer;
d) pressing said stack by means of a press plate, said press plate comprising embossing means and heating means,
wherein said embossing means during pressing provide said floor panel with said embossments, and
wherein said heating means during pressing causes said modified melamine-formaldehyde resin to harden and said top layer to adhere to said substrate.
6 . The method according to claim 5 , wherein the modified melamine-formaldehyde resin further comprises polyol in an amount within a range of from 1 to 5%, by weight based on a total liquid weight of the resin.
7 . The method according to claim 6 , wherein said polyol is glycerol.
8 . The method according to claim 5 , wherein said substrate comprises medium-density fibreboard or high-density fibreboard.
9 . The method according to claim 5 , wherein said top layer comprises a decorative layer, said decorative layer comprising a printed carrier.
10 . The method according to claim 9 , wherein the decorative layer is impregnated with said modified melamine-formaldehyde resin.
11 . The method according to claim 5 , wherein in step d) said press plate exerts a pressure of between 20 to 80 bar to said stack, a temperature during pressing is between 15° and 200° C., and a duration of the pressing is between 12 to 60 seconds.