AU609057B2

AU609057B2 - Spray device

Info

Publication number: AU609057B2
Application number: AU78678/87A
Authority: AU
Inventors: Keith Wallace Painter
Original assignee: AUSTEC HOLDINGS Pty Ltd
Current assignee: AUSTEC HOLDINGS PTY Ltd
Priority date: 1982-04-30
Filing date: 1987-09-17
Publication date: 1991-04-26
Anticipated expiration: 2003-04-29
Also published as: AU7867887A

Description

r i

AUSTRALIA

PATENTS ACT 1952 6 0 COMPLETE SPECIFICATION V

(ORIGINAL)

FOR OFFICE USE Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: This document contains the amendments made under Section 49 and is correct for printing.

B^ mna~m Name of Applicant: Address of Applica Actual Inventor: Address for Service TO BE COMPLETED BY APPLICANT AUSTEC HOLDINGS PTY LIMITED nt: 215-216 Parramatta Road HOMEBUSH NSW 2140 AUSTRALIA Keith Wallace Painter e: ARTHUR S. CAVE CO.

Patent Trade Mark Attorneys Goldfields House 1 Alfred Street SYDNEY N.S.W. 2000

AUSTRALIA

P r 1 Complete Specification for the invention entitled SPRAY DEVICE.

Yr The following statement is a full description of this invention Sincluding the best method of performing it known to me:ella 1 ASC 49 j 0407k/SC This invention concerns a spraying method and a spray device for spraying viscous liquids.

The invention will be described with particular preference to its suitability for adhesive application in a laminating machine, but those skilled in the spraying art will appreciate that the device may also find application not only in the manufacture of building boards but in food processing and in defence industries.

In the manufacturing of laminated building boards, it is S known to coat surfaces with rollers if thin films of viscous liquids are desired. It is also known to atomise the adhesive S in a spray gun relying upon compressed air to shear the *to o0 liquid. In the manufacture of some panels, for example coolroom panels, it has been found that a uniform film of adhesive between the contacting surfaces of the different layers is not necessary, with resulting economy of adhesive.

~oo8 Moreover, the cost of providing a continuous supply of 00 compressed ai is an appreciable factor in production costs.

The degree of atomisation which results from airless spraying *Go" is not necessary either, although this obviates the need to S supply compressed air.

e oos 0 In one broad aspect this invention provides a method of bonding a laminate to a substrate comprising: feeding a laminate and a substrate into a laminating roll press such that the laminate comes into contact with the substrate at a first roll; locating at least two spray heads adjacent to the surface to be sprayed; each spray head discharging one of at least two viscous liquids; 2 0407k/SC metering the liquid to each spray head, to ensure the liquids discharged from the at least two spray heads are discharged in a predetermined and exact ratio to one another; ejecting the liquid from each spray head toward the surface by application of gas pressure in order to achieve partial mixing of the liquids ejected from the spray heads at the surface by producing partial overlapping of the liquids in a spatter distribution on the surface.

9. completing the mixing of the at least two component adhesive at the first roll where the laminate comes into contact with the substrate such that the mixed adhesive is distributed between the laminate and the substrate.

Preferably the spray heads are traversable over the surface to be sprayed, the connections to the metering pump and *e gas supply being by flexible conduits.

a *491 t 4 4 3 Even though this method of adhesive application simplifies the use of multi-pack adhesives, the problem with applying such'adhesives to laminating surfaces in the manner described remains. Due to the bulk of the spraying apparatus and the methods by which the laminate is applied to the substrate, a physical limit is imposed as to the minimum distance which may be achieved between the point of application of the adhesive and the point where the laminate comes into contact with the substrate.

Subsequently, it has been found that if the two pack adhesives are totally mixed at the point of application to the surface, by the time the laminate has been brought into contact o.

with the substrate the adhesive has undergone considerable a 00 oo chemical reaction, thus by the time the laminate/substrate a DIT sandwich has reached a reasonable contact point, usually 9 se between the first and second rolls of a laminating roll press, the adhesive has reacted beyond what is known as the tack time .9 of the adhesive, being the stage at which the best adhesion between the two surfaces may be obtained, resulting in poor adhesion between the laminate and the substrate.

As it is necessary for adhesion of the surfaces to commence between the first and second rolls of a laminating o: roll press and end between the third and fourth rolls, it is critical that the total mixing of the two pack adhesive take place substantially at the contact point of the laminate and ,ubstrate.

To achieve this result, it is necessnry to mix only sufficient of the ingredients at the time of application to the 4 0664E

I

e 00 0 0 01 8 o 00 o oc 88 0 8 surface to commence the chemical reaction, as the chemical reaction initially causes foaming of the adhesive thus producing a mechanism to establish complete mixing of the adhesive at the contact point between the laminate and substrate.

As foaming commences, the adhesive expands. Subsequently as the foamed adhesive reaches the contact point between the laminate and the substrate a foaming mixer is created which causes the adhesive components to mix totally and form a thin layer of adhesive between the laminate and the substrate. By mixing the adhesive components at this point the adhesive 00 bonding between the laminate and the substrate will commence between the first and second rolls of the laminating roll press 00 and finish between the third and fourth rolls as required.

00 15 This method of mixing is particularly useful with two pack 008 polyurethane although similar results can be achieved with any multi-pack adhesives.

°00 It has further been found that by heating the laminate to o a temperature of between 20 C and 60 C, limiting the 00: maximum feed rate of the laminate and substrate to 2-3 meters per minute, using polyester and iso-cyanate in ratios of S between 50%:50% to 70%:30% and pressurised air pressure of 1-2 bar, optimum adhesive bonding between the laminate and 0 substrate may be achieved.

Thus it can be seen that substantial inventiveness has been applied to overcome the secondary problems associated with applying viscous liquids to solid surfaces with respect to the adhesive bonding of laminated panels.

88 5 0664E 0407k/SC One embodiment of the device is now described with reference to the accompanying drawings in which FIG. 1 is a plan of the apparatus set up for spraying a two-component glue.

FIG. 2 is a front view of the same apparatus.

FIG. 3 is a diagrammatic section of a spray head and a fragment of the apparatus.

Referring now to Figs. 1 and 2, sheet steel 2 about 1500 mm wide is fed continuously by nip rolls not shown into a oo° laminating machine which is not illustrated but is also Q° described in one co-pending application no. PF 3854. Adhesive 'S must be applied to the vertical surface of the steel as the latter feeds slowly past the spreading apparatus. The apparatus has a vertical post 4 supported on a pedestal 6. Two horizontal rails 8 support a LH and RH pair of mutually parallel vertical guides 10 fabricated from angle iron. A crosshead 12 rises and falls in the guides under the influence S of a double acting ram 14 with a stroke of about 140 mm.

Two spray heads 16 are clamped to brackets 18 on swivel *@09 mounts 20. Each head end is spaced from 10 to 50 mm from the surface of the steel 2, the most preferred spacing being 40 mm rro 0o° and the sprays from each head are arranged to partially converge at the surface of the sheet 2. Referring now to FIG. 3 each head has an outer tube 22 with a nozzle 24 and an inlet 34 for one component of the adhesive which is supplied by a metering pump (not shown) through coiled flexible conduit 26 at 2 to 3 psi. The other component is supplied to the remaining head at 0.5 psi due to lower liquid viscosity.

1- 6 T1 0 r I- Coiled flexible conduit 28 conveys compressed air at about psi to inner tube 30 which ends in a nozzle 32 set just behind the nozzle 24.

In use, under steady conditions the components are ejected from each spray head toward the surface to be sprayed and coincide so as to partially mix on the surface of the steel in a zig zag pattern imposed by the ram.

The total mixing of the components caused by the rolling foam mechanism previously described.

The advantages of this embodiment have been found to be as follows: 1. The device is economical in the use of air.

oo 2. Satisfactory mixing of components is achieved where mixing o 0 0oo° is necessary.

"1"1 3. Satisfactory distribution of the sprayed components is S009 possible with improved contact area in the finished product.

It will be obvious to those skilled in the art that 00 00 modifications and variations to the present invention may-be .210: made within the scope and spirit of the present invention. As such, it is the intention of the present invention to include :0o such modifications and variations as would be obvious.

7 7 0664E

Claims

1. A method of bonding a laminate to a substrate comprising: feeding a laminate and a substrate into a laminating roll press such that the laminate comes into contact with the substrate at a first roll; locating at least two spray heads adjacent to the surface to be sprayed; each spray head discharging one of at least two viscous liquids; S(c) metering the liquid to each spray head, to ensure the o liquids discharged from the at least two spray heads are "discharged in a predetermined and exact ratio to one another; ejecting the liquid from each spray head toward the surface by application of gas pressure in order to achieve partial mixing of the liquids ejected from the to$spray heads at the surface by producing partial

4.4, overlapping of the liquids in a spatter distribution on the surface. "1 completing the mixing of the at least two component adhesive at the first roll where the laminate comes into contact with the substrate such that the mixed adhesive is distributed between the laminate and the substrate. 2. The method of claim 1 wherein adhesion of the adhesive to the laminate and substrate surfaces occurs between the first and second rolls of the laminating roll press. 3. The method of claim 1 or claim 2 wherein the strength of adhesion of the adhesive to the laminate and substrate substantially finishes increasing between third and fourth rolls of the laminating roll press.

8- A'T 0 0407k/SC 4. The method according to claim 1 wherein each liquid forms one component of a multi-component adhesive. The method of any one of the preceeding claims wherein partial mixing of the liquids on the surface is caused by ejecting the liquids along divergent paths which cause the liquids to partially intersect at the surface. 6. The method according to any one of the preceeding claims wherein the distance between the surface to be sprayed and the 0# S at least two spray heads is 10 to 50 mm. I' o 7. The method of bonding a laminate to a substrate according a to any one of claims 1 to 6 wherein the laminate and substrate II S feed rate is between 2-3 metres per minute. 8. The method of bonding a laminate to a substrate according to any one of claims 1 to 7 wherein the two component adhesive is polyester and iso-cynate.

9. The method of bonding a laminate to a substrate according ri t Sto claim 8 wherein the polyester and iso-cyanate are mixed in the ratios of 50% polyester 50% iso-cyanate to 70% polyester 30% iso-cyanate.

10. The method of bonding a laminate to a substrate according trr to any one of claims 1 to 9 wherein partial mixing of the at least two component adhesive creates a foam which is drawn into a point of contact between the laminate and substrate such that 7a foaming roll is formed which aids in mixing of unmixed components of the at least two component adhesive.

11. A method of bonding a laminate to a substrate according to any one of claims 1 to 10 wherein the laminate is heated to between 20°C and -9- 0407k/sc

12. A method of bonding a laminate to a substrate substantially as herein described. DATED this 1st day of November, 1990. AUSTEC HOLDINGS PTY LTD By Its Patent Attorneys ARTHUR S. CAVE CO. 0 06 00 000 000 0 000 10