Abrasion overlay paper is a half-transparency thin paper with hard corundum
grains berried inside it. Has been fully saturated with melamine, the paper
looks like a half-flexible film after curing. When hot-pressed on board the
decorated paper as well as the wood panels, it bonds and becomes transparency.
A layer of wear resistance with good hand tough feeling has been formulated
on the surface.
The function of wear resistance towards a panel, especially the laminated
flooring or the table furniture is so important that can extend a lot the
lifetime of a product or keep fresh its beauty for longer time.
Technically, the performance in wear resistance depends on the following four
approaches:
The resin, now popularly use melamine which is a comparatively
cheaper and easy handle one. Needless to say, the resin itself has a certain
function of wear resistance, like the paint on the surface of various kinds.
However, the melamine is not hard enough for flooring or table furniture.
If impose a round test, a layer of pure melamine with 150 micro thick after
cure only stand about 450 rounds. Therefore, it should add something hard
to support it.
Hard corundum, if it is pure enough, the hardness can reach
9.3 (Morse). Theoretically, the intruding of any hard material inside the
layer should be smallest in quantity but hardest in quality, especially for
wear resistance rather than anti-scratching. Hardness is the basic demand
for this purpose. Smallest in quality is the less the other material, the
more stable and transparency of the melamine layer. In this view, the diamond
is the most ideal one as the intruding hardness, but it is too expensive.
The most famous hard corundum in the world used in laminated field is the
SPW 180 or SPW 220, which are of pure, hard and much better in shape.
Well and reasonable distribution of the corundum inside the
melamine. The corundum can not be too much. Base on experience, the quantity
per one square meter could be 8 – 25 g of corundum grains. At the same time,
it should prevent the corundum go together to form a “sand beach”. The hard
corundum should be spread out as much even as possible. In this mean, the
paper with the wood fiber can fulfill this purpose, it make the particles
located more even and reasonable, needless to considering the later flowing
of the liquid melamine. Secondly, the vertical positioning of each grain and
the real diameter of the particles should be taken into consideration. As
an ideal case, the corundum should be placed in the middle or mid-lower level
of the melamine after curing, to prevent from emerging out to the air. The
diameter should be controlled and in compatible with the actual thickness
of the try melamine layer. Theoretically speaking, 3/4 is the most idea, but
in actually, 1/2 or a little bit bigger. Comparing with liquid overlay method,
use abrasion paper is an ideal way, since the paper acts like a net to fix
and cover.
The quality of the bonding between resin and corundum as
well as the resin itself. If the resin has too much bubbles, the surface of
the layer could be like “marsh”, and the clearness as well as the wear resistance
can not be good even have a good quality of abrasion paper. To increase the
harmony force between the resin and the corundum, some additives are usually
recommended. Also the abrasion paper itself should be made suitable for melamine
saturation.
