WO2002002481A2

WO2002002481A2 - Coating process for fibre-cement boards and resulting products

Info

Publication number: WO2002002481A2
Application number: PCT/NZ2001/000132
Authority: WO
Inventors: Graham Michael Crowley
Original assignee: Graham Michael Crowley
Priority date: 2000-07-03
Filing date: 2001-07-03
Publication date: 2002-01-10
Also published as: AU2001280301A1; WO2002002481A3

Abstract

A process for coating fibre-cementitious boards, involves the application of a thermosetting adhesive transfer film to the surface of the board, which may have been primed, and rolling the transfer film under pressure onto the board by means of a heated resiliently-surfaced roller.

Description

A COATING PROCESS AND RESULTANT PRODUCT

TECHNICAL FIELD

This invention relates to an improved coating process which is

particularly applicable to fibre-cementitious materials such as those

sold, particularly in Australasia, under the trade mark Hardiflex,

Hardiboard, Hardiplank and similar brands produced by others such as

CSR Pty Ltd of Australia.

BACKGROUND ART

Such materials are difficult to coat because their porosity, and

uniformity of structure varies. This creates difficulty when applying

paint coatings or when applying adhesives. The end result is poor

bonding leading to an unacceptable product resulting in high reject

rates.

It was therefore an object of the present invention to provide a

coating system and resultant product which overcame the above

mentioned difficulty or which would at least provide the public with a useful choice.

DISCLOSURE OF THE INVENTION

The present invention consists in a coating system comprising the

steps of imparting relative movement between a fibre cementitious

board and a workstation; at the workstation progressively applying a

thermosetting adhesive transfer film to the fibre cementitious board

and rolling the transfer film under pressure onto the fibre cementitious

board by means of a heated resiliently-surfaced roller, thereby

bonding or adhering the adhesive to the fibre cementitious board.

Preferably the transfer film may be stripped off the bonded surface by

a winding process.

Preferably the stripped surface is subsequently coated with an ultra

violet cured coating.

Preferably such coating is applied by spray, roller or curtain coating

methods. Preferably such a film is clear.

Preferably the fibre cementitious board should be sealed with a

suitable primer coating of acrylic or silicate compounds such as Bostik

(trademark) L3 Primer. A better product for that purpose is Mirotone

(trademark) Mirocure UV7750 which is an acrylic coating.

The invention also includes the resultant product of the process.

MODES FOR CARRYING OUT THE INVENTION

In order to coat fibre-cementitious material such as Hardiboard,

Hardiplank, CSR cent fibre sheeting etc, usefully done to glamorise

the surface of a rather spartan product, a Kurz (trademark) foil

transfer machine or similar is utilised along with transfer foils such as

Kurz transfer foil "SR superior" or similar. A good foil to use is their

BASR super scratch resistant foil.

The machine basically consists of a bed of rollers adapted to progress

a board through the workstation. There is also an overhead roller

which mounts the coil or roll of transfer foil, or stamping foil as it is optionally called, and there is a large silicone, resiliantly-surfaced roller

which is heated and which is adjustable to allow variation of the

downward pressure it imparts on the board travelling through the

machine. The adhesive on the transfer foil is melted by the silicone

roller and it has been found unexpectedly that the porosity variations

in the fibre-cement board and the surface variations of the board do

not prevent effective bonding.

The transfer foil may have any suitable pattern applied in the usual

way to the usually clear plastic film which contacts the heated roller

and which is subsequently stripped from the board once the bonding

process has taken place. The pattern or colour applied to the transfer

film transfers over to the adhesive.

Of course it would be possible to use the transfer foil without any

printed pattern and merely as a means of coating the board surface

with adhesive to provide a suitable substrate for subsequent coatings.

On the other hand where a pattern has been applied to the transfer

foil the finished product can be in simple plain colours such as cream,

white, black, red etc or finished with wood grain or stone or granite etc patterns for example. This effects a major transformation of the

underlying fibre cementitious board adding considerably to its value

and to its end uses. The transfer film may be progressively wound

off the bonded surface onto a roller on the machine or, alternatively,

can be left in place if no other surface treatment is required, to

protect the surface until the board is installed.

For some applications it may be desirable to remove the film

immediately after bonding has occurred and to apply an ultra violet

cured coating by means of spray, roller or curtain coating techniques.

Suitable coatings are supplied by Whitehall Technical Services Ltd and

they may incorporate ceramic beads or aluminium silicates for

instance to give scratch resistance. Such coatings may be clear, they

may be coloured, be satin or high gloss, or they may impart a

textured surface to the board. Other coatings than ultra violet cured

might also be suitable.

One particular application of the coating technique is to provide a

bonding surface which effectively isolates the variable porosity and

irregularities of the fibre cementitious board from a subsequent

coating. For example that subsequent coating may be an adhesive to secure laminates in sheet or continous coil form, such as FORMICA

(registered trade mark), to the surface of the board.

Because of the resiliance of the silicone roller it is possible to use the

method to apply a coating even to a patterned fibre cementitious

surface such as one resembling wood grain, which is widely used as a

weatherboard; or a tile, which is widely used as a wall lining in

showers or kitchens or bathrooms.

It is also possible to have suitable foil transfers with signage on them

so that when applied the fibre-cementitious board is immediately

converted to a sign e.g. a road sign.

It is advantageous to precoat the board before applying the transfer

film to secure superior adhesion which might be required in some

applications. This is done using a ultra violet cured film of acrylic, a

suitable product is Mirotone, Mirocure UV7750. That product can be

formulated with talc, enabling ready sanding after coating, or with

pigments. The board does not cup when coated and curing is

complete within seconds so following steps in the desired process are

not delayed.

Claims

1 . A coating system comprising the steps of imparting relative

movement between a fibre-cementitious board and a workstation; at

the workstation progressively applying a thermosetting adhesive

transfer film to the fibre-cementitious board and rolling the transfer

film under pressure onto the fibre-cementitious board by means of a

heated resiliently-surfaced roller, thereby bonding or adhering the

adhesive to the fibre-cementitious board.

2. The process of claim 1 wherein the transfer film is stripped off

the bonded surface by a winding process.

3. The process of claim 2 wherein the stripped surface is

subsequently coated with an ultra-violet cured coating.

4. The process of claim 3 wherein such a coating is clear.

5. The process of claim 1 wherein the fibre-cementitious board is

sealed with a suitable ultra-violet cured primer coating of acrylic prior

to applying the thermosetting adhesive transfer film.

6. The resultant product of the process claimed in any one of

claims 1 to 5.

7. The product of the process both substantially as herein

described.