TUILE DE PLAFOND RESISTANT A L'EAU

WATER RESISTANT CEILING TILE

Abrégé français

La présente invention concerne une tuile de plafond, comprenant un cur, un revêtement d'aspect sur un côté avant de la tuile, et un revêtement étanche à l'eau à l'arrière de la tuile. Le cur comprend une charge technique, un liant, et des éléments de fibre séchés à partir d'une boue ou d'une pâte à base d'eau desdits éléments. Le cur est perméable à l'eau, et contient un matériau de production de couleur non blanche pouvant être libérés hors du cur par percolation d'eau à travers le cur. Le revêtement d'apparence présente une réflectivité lumineuse élevée du fait qu'il contient un constituant coloré blanc et du fait qu'il est perméable à l'eau. Le revêtement étanche à l'eau sert à repousser et à faire perler les gouttes d'eau déposées à l'arrière de la tuile.

Abrégé anglais

A ceiling tile comprising a core, an appearance coating on a face side of the tile, and a waterproof coating on a backside of the tile, the core including a filler, binder, and fiber elements dried from a water based slurry or paste of said elements, the core being water permeable and containing a non-white stain producing material susceptible to being leached out of the core by water percolating through the core, the appearance coating exhibiting a high light reflectivity by virtue of containing a white colored constituent and being pervious to water, the waterproof coating serving to repel and bead- up water droplets deposited on the backside of the tile.

Revendications

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WHAT IS CLAIMED IS:
1. A ceiling tile comprising a core, an appearance
coating on a face side of the tile, and a waterproof
coating on a backside of the tile, the core including a
filler, binder, and fiber elements dried from a water based
slurry or paste of said elements, the core being water
permeable and containing a non-white stain producing
material susceptible to being leached out of the core by
water percolating through the core, the appearance coating
exhibiting a high light reflectivity by virtue of
containing a white colored constituent and being pervious
to water, the waterproof coating serving to repel and bead-
up water droplets deposited on the backside of the tile.
2. A ceiling tile as set forth in claim 1, wherein
the fiber element includes mineral fiber.
3. A ceiling tile as set forth in claim 1, wherein
the appearance coating is a dried water based white paint
layer.
4. A ceiling tile as set forth in claim 1, wherein
the waterproof material is a dried and cured water carried
material.
5. A ceiling tile as set forth in claim 4, wherein
the waterproof material is a fluorocarbon polymer emulsion.
6. A ceiling tile as set forth in claim 5, wherein
the waterproof material is applied with a coverage of
solids at a rate of about 1/5 to 1/4 grams/sq. ft.

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7. A method of making a waterproof ceiling tile
comprising creating a core by mixing materials in the
presence of water, drying the materials to form a rigid
board, applying a water based appearance coating on the
appearance side of the core, and a waterproof water based
coating to a side of the core opposite to the face side.
8. A method of making a suspended ceiling tile as set
forth in claim 7, wherein said appearance coating and
waterproof coating are applied and are thereafter
simultaneously dried by exposing said coatings to a heated
environment at about 220° C. for about 45 seconds.

Description

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WATER RESISTANT CEILING TILE
BACKGROUND OF THE INVENTION
[0001] The invention relates to improvements in
construction panels and, in particular, to ceiling tiles
made from a water slurry or a water based paste.
PRIOR ART
[0002] Construction panels, particularly, water
pervious ceiling tiles have a tendency to become stained
when exposed to water. One mechanism that occurs to bring
water droplets in contact with a ceiling tile is
condensation on pipes and ductwork existing in the space
above the ceiling. The condensate can drip onto the
backside of the ceiling tile and migrate to the visible
appearance side of a tile. Staining can occur because the
water can carry off contaminants from surfaces it contacts
and, often, because the water droplets migrate through a
ceiling tile and leach tannin from recycled newsprint or
other plant based cellulose materials and staining agents
from other components used in the tile composition bringing
such staining agents to the front surface of the tile.
[0003] As is typical of most products, cost is
critical and there is a need for an economical solution to
minimize water stains on the appearance sides of
construction panels, particularly, water pervious ceiling
tiles.
SUMMARY OF THE INVENTION
[0004] The invention provides an economical
solution to water staining at the visible face of
construction panels due to water migration through the

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panel. More specifically, the invention involves the
realization that by creating a barrier to water droplets
locally at the backside of a panel, the droplets can be
caused to evaporate before their liquid content can migrate
through a panel.
[0005] It has been discovered that commercially
available material used to impart water repellency to
fabric is an excellent medium for accomplishing the
objective of the invention. Such material is widely
available, non-toxic, and relatively inexpensive in the
limited coverage found to be effective in practicing the
invention. The preferred waterproof material can be
applied with a water carrier by a simple application of the
same to the backside of a rigid mat from which the tile is
fabricated. The very light coverage and consequent low
cost of the waterproofing treatment and the simplicity of
application makes it practical for use in even the less
expensive product lines of a panel manufacturer.
[0006] The core mat or tile is preferably subjected
to an elevated temperature to quickly force dry or cure the
waterproofing material before the carrier water can be
absorbed through the core mat. Preferably, this drying
process can be done simultaneously with the conventional
process step used to dry a finish coat or paint on the
visible side of the tile or panel.
BRIEF DESCRIPTION OF THE DRAWING
[0007] FIG. 1 is a diagrammatic isometric view of a
ceiling tile embodying the invention; and
[0008] FIG. 2 is a schematic diagram of a process
utilizing the invention.

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DESCRIPTION OF THE PREFERRED EMBODIMENT
65% perlite filler
18% paper fiber
7% unmodified starch binder, and
10% mineral wool fiber.
considerably, say up to about 25% and in such a case, the
perlite can be reduced accordingly. Besides paper fiber,
other cellulose sources can be used such as wood or woody
plant materials. When these constituents have been
properly mixed in a water slurry and spread on a screen, in

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the case of a water felted product, or similar constituents
are spread on a pan in the case of a cast tile, they are
dewatered and/or dried into a rigid board. Thereafter, the
appearance or front side of the board or tile preform is
coated with an appearance coating or paint usually a water
based material having some latex or other binder component.
In the case of a water felted mat or core, the finish side
of the mat, if necessary, can be ground to create a flat
surface prior to coating with a finish or top coating.
Additionally, prior to application of the finish coat, a
primer coat, that may be clay based, for example, can be
applied to the face side of the mat. The tile 10 of FIG. 1
is shown in its installed orientation and includes an
appearance coating 11 on its lower, visible face, a primer
coat 12, a water felted mat or core 13, and a waterproof
coating 14, discussed below, on its back or upper face.
[0011] The appearance coat 11 on the finish side of
the tile 10, as mentioned, is typically a water based
coating with a white pigment color to provide high light
reflectivity. It has been discovered that
commercially available fabric waterproofing material can be
used to successfully waterproof the back of the tile 10 by
coating the mat 13 with such material. Surprisingly, it
has been found that only relatively small quantities of
such material need be used to achieve satisfactory results.
An example of a product suitable for practicing the
invention is a fluorocarbon polymer emulsion such as that
marketed by Daikin Chemical Europe GmbH, Dusseldorf,
Germany, under the brand TG-5601. This product is a water
based emulsion which can be greatly diluted with water
while remaining effective even when the application rate is
imprecise. The result of the dilution of the original

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emulsion is a very light coating of waterproofing solids of
about 1/5 to 1/4 grams/sq. ft. Despite such a low
concentration of solids, it has been found that a
surprising degree of waterproofing and resistance is
achieved. With the disclosed solids coverage rate, water
droplets on the coating 14 simply bead-up and eventually
evaporate.
[0012] FIG. 2 illustrates an example of a process
for practicing the invention. A dried mat or board 13 made
by a conventional water felting process with a solids
content such as described above is carried on a conveyor 20
into a spray booth 21 where a water based top coat or paint
11 is applied. The top coat or appearance coat 11 faces up
in this process but when the tile is installed in a
ceiling, the top coat faces down. The mat 13 is conveyed
from the spray booth to a dryer 22 by a roller conveyor 23.
A sprinkler 24 carrying a plurality of spray nozzles
extends between a pair of rolls of the conveyor 23 across
the width of the conveyor. The sprinkler 24 sprays the
underside of the mat 13 with dilute waterproofing liquid 14
described above. The mat 13 coated with the top coat 11
and waterproof material 14 is conveyed by a conveyor 26
through the dryer 22 where these coatings are preferably
simultaneously dried and/or cured for example, at a
temperature of about 220 C. for a duration of about 45
seconds. Other methods of applying the top coat and
waterproofing material are contemplated. For example, roll
coating or flooding can be employed.
[0013] Water condensate dripping from piping and
ducts within the space or plenum above a suspended ceiling
can fall onto the backside of a prior art ceiling tile
eventually causing discoloration on the face or appearance

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side. This mechanism of discoloration or staining can be
attributed to percolation of the condensate water through a
tile. The condensate may be contaminated by surfaces it
passes over before reaching the tile. Additionally, as the
water percolates through the body of the tile, it can leach
stain producing material such as tannins present in the
paper or cellulose fibers. The contaminated water can leak
through the appearance coating and thereby stain it. Water
passage through a tile, where the invention is not
employed, is commonplace where there is a source of water,
since it is desirable that the ceiling tile be porous to
exhibit good sound absorbing characteristics. Adding to
the desired porosity of a typical ceiling tile is its
original water based character which inherently leaves it
permeable to water.
[0014] It should be evident that this disclosure is
by way of example and that various changes may be made by
adding, modifying or eliminating details without departing
from the fair scope of the teaching contained in this
disclosure. The invention is therefore not limited to
particular details of this disclosure except to the extent
that the following claims are necessarily so limited.

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