IES20010326A2 - A method for manufacturing a foam board - Google Patents

Abstract

A rigid polymeric insulating foam board of the type comprising a lower facer (1), an upper facer (2) and a foam layer (3) between the facings (1,2) is manufactured by leading the lower facer (1) from a supply reel to a lay-down area (5) at which streams (6) of liquid foam reactants are laid down onto the lower facer (1) through separate nozzles (9). The upper facer (2) is led from a supply reel over the foam reactants. The sandwich thus formed is then led into a laminator (10) in which the foam expands and a continuous length of rigid polymeric insulating foam board (15) is formed. The board (15) is led through an insulating tunnel (20) and then cut to a desired length. The lower facer (1) is preheated by leading the facer (1) over a heated bed (30) which is heated to a temperature of from 35 to 85°C. <Figure 1>

Description

JiA^iETHOD FOR MANUFACTURING A FOAM BOARD” KING35/C/IES Introduction The invention relates to a method for manufacturing a rigid polymeric insulating foam board of the type comprising a lower facer, and upper facer and a foam layer between the facers.

There are several different methods for manufacturing such boards in a substantially continuous manner. There is however a need to optimise the rate of production with optimised quality, reduced labour and raw material costs and reduced reject rates. There is therefore a need for an improved manufacturing process which will overcome this problem.

Statements of Invention According to the invention there is provided method for manufacturing a rigid polymeric insulating foam board of the type comprising a lower facer, an upper facer, and a foam layer between the facers, the method comprising the steps of: preheating a base facer; leading the preheated base facer to a lay down area; laying a plurality of transversely spaced-apart streams of liquid foam reactants onto the preheated base facer; OPEN TO PUBLIC INSPECTION UNDER SECTION 28 AND RULE 23 IE010326 KING35/C/IES -2heating the base facer with the streams applied thereon, the streams of liquid foam reactants spreading across the base facer as the foam expands; leading an upper facer over the at least partially spread foam reactants; leading the sandwich thus formed into a laminator comprising upper and lower laminator conveyors, the upper laminator conveyor checking the rise of the foam and preventing over-expansion; and cutting the rigid polymeric foam board thus formed to a desired length.

In a preferred embodiment of the invention method as claimed in claim 1 wherein the base facer is preheated by direct contact with a heating source. Most preferably the base facer is preheated by leading the facer over a heated bed. In a preferred embodiment the heated bed is at a temperature of from 35 to 85°C.

Desirably the heated bed comprises at least two adjacent sections over which the base facer is led. In this case at least some of the heated bed sections may be heated to different temperatures.

In a further embodiment the method includes the step of heating the base facer with the streams of liquid foam reactants applied thereon prior to application of the upper facer.

In this case, preferably the base facer and liquid foam reactants are heated by passing the facer with liquid foam reactants applied thereon across a heated bed. Preferably the heated bed is heated to a temperature of from 40 to 95°C. Ideally IE010326 KING35/C/IES -3the heated bed is heated to a temperature corresponding approximately to the temperature in the laminator.

In another embodiment the heater bed includes passageways through which a vacuum is applied to draw the base facer to the surface of the heater bed.

In a further embodiment the method includes the step of confining the side edges of the foam board in the laminator. In this case, preferably the laminator includes a lower slatted laminator conveyor and the slats of the conveyor are provided with edge flights to confine the side edges of the board in the laminator.

Preferably the method includes the step of leading the polymeric board from the laminator through an insulated tunnel prior to cutting of the board to length.

In a preferred embodiment each stream of liquid foam reactants is delivered onto the preheated base facer from an independent outlet nozzle.

The invention also provides a rigid polymeric insulating board whenever manufactured by the method of the invention.

Brief Description of Drawings The invention will be more clearly understood from the following description thereof given by way of example only in which: Fig. 1 is a diagrammatic side, partially cross sectional view illustrating various steps in a method for manufacturing a foam board; Fig. 2 is a perspective view of a lay down area used in the method of the invention; IE010326 KING35/C/IES -4Fig. 3 is a cross sectional view on the line A-A I Fig. 1; Fig. 4 is a cross sectional view on the line B-B in Fig. 1; Fig. 5 is a cross sectional view on the line C-C in Fig. 1; Fig. 6 is a diagrammatic cross sectional view of part of a laminator used in the method of the invention; Fig. 7 is a perspective, partially cut-away view of an insulated tunnel used in the method of the invention; Fig. 8 is a side view of the tunnel of Fig. 7; and Fig. 9 is a cross sectional view on the line D-D in Fig. 8.

Detailed Description Referring to the drawings there is illustrated a method for manufacturing a rigid polymeric insulating foam board of the type comprising a lower facer 1, an upper facer 2 and a foam layer 3 between the facings 1,2.

Referring particularly to Fig. 1, in general, in the method of the invention the lower facer 1 is led from a supply reel to a lay-down area 5 at which streams 6 of liquid foam reactants are laid down onto the lower facer 1 through separate nozzles 9. The upper facer 2 is led from a supply reel over the foam reactants. The sandwich thus formed is then led through a laminator 10 in which the foam expands and a continuous length of rigid polymeric insulating foam board 15 is IE010326 KING35/C/IES -5formed. The board 15 is led through an insulating tunnel 20 and then cut to a desired length.

The lower facer 1 is preheated by leading the facer 1 over a heated bed 30 which is heated to a temperature of from 35 to 85°C. In this case the heated bed 30 comprises three separate in-line sections 30a, 30b, 30c over which the facer 1 is led and the nozzles 9 through which the streams 6 of liquid foam reactants are led are located at the downstream end of the second heater bed section 30b. Each of the heater bed sections 30a, 30b, 30c has embedded channels for flow of heating fluid. Between the channels the bed sections have a plurality of through vertical passageways 34 through which a vacuum may be drawn by a vacuum box and associated vacuum pump. A vacuum may be applied to the passageways 34 to draw the facer 1 onto the surface of the heater to further enhance heat transfer to the facer.

The heater bed sections 30a, 30b are typically heated to about 60°C and as the facer 1 is led over the heated bed it is heated so that when the liquid foam reactants 6 impinge on the facer they are immediately heated. This speeds up the reaction and aids the spread of the streams 6 across the facer from the separated configuration of Fig. 3 on lay-down, through a partially spread configuration of Fig. 4 on entry to the laminator 10 to the fully spread and expanded configuration of Fig. 5. The facer 2 is also preheated by passage through portion of the laminator 10 which is typically at about 60°C prior to application to the foam. Because the facer 1 is preheated the prepolymer reactants delivered through the nozzles 9 can be relatively cool which maximises the useful operating life of the nozzles 9. The preheating of the facer leads to a smooth outer surface finish as the separate streams 6 spread and integrate with one another forming flat outer surfaces. Thus, problems of de-lamination are avoided. The method therefore provides a rigid polymeric insulating board with an excellent consistent surface finish.

IE010326 KING35/C/IES -6Referring to Fig. 6 the laminator 10 comprises an upper slatted conveyor 50 and a lower slatted conveyor 51 which define a fixed gap therebetween to which the foam sandwich is allowed to rise. The upper laminator conveyor 50 checks the rise of the foam and prevents over-expansion. In this case side flights 52 are fixed to and move with the lower conveyor 51. Each slat of the conveyor 51 has an associated side flight 52. A release agent is applied to the surface of the flights 52 facing the foam board sandwich to aid release of the flight 52 from the board as the board exits the laminator. The flights 52 provide clean side edges on the foam board which minimises wastage on trimming.

The insulated tunnel 20 through which the continuous board 15 passes is formed with side and top insulating panels 26, 27. At least the top panels 27 may be individually movable or removable for ease of assembly, re-arrangement or disassembly of the tunnel 20. We have found that passing the foam board through such an insulating tunnel allows the foam forming reaction to proceed to completion and thereby increases the green strength of the foam board prior to cutting. This is achieved without having to slow down the speed of the line.

The upper and lower facer is of a suitable flexible material such as paper and/or plastic and/or metal foil and/or glass fibre.

The foam formulation may be of any suitable type such as a conventional polyurethane, polyisocyanurate or phenolic foam.

The invention is not limited to the embodiments hereinbefore described which may be varied in detail.

Claims (5)

Claims

1. A method for manufacturing a rigid polymeric insulating foam board of the type comprising a lower facer, an upper facer, and a foam layer between the facers, the method comprising the steps of: preheating a base facer; leading the preheated base facer to a lay down area; laying a plurality of transversely spaced-apart streams of liquid foam reactants onto the preheated base facer; heating the base facer with the streams applied thereon, the streams of liquid foam reactants spreading across the base facer as the foam expands; leading an upper facer over the at least partially spread foam reactants; leading the sandwich thus formed into a laminator comprising upper and lower laminator conveyors, the upper laminator conveyor checking the rise of the foam and preventing overexpansion; and cutting the rigid polymeric foam board thus formed to a desired length. ΪΕ010326 KING35/C/IES -82. A method as claimed in claim 1 wherein the base facer is preheated by direct contact with a heating source, preferably the base facer is preheated by leading the facer over a heated bed, ideally the heated bed is at a temperature of from 35 to 85°C, preferably the heated bed comprises at least two adjacent sections over which the base facer is led, at least some of the heated bed sections may be heated to different temperatures.

2. 3. A method as claimed in any preceding claim including the step of heating the base facer with the streams of liquid foam reactants applied thereon prior to application of the upper facer, preferably the base facer and liquid foam reactants are heated by passing the facer with liquid foam reactants applied thereon across a heated bed, preferably the heated bed is heated to a temperature of from 40 to 95°C, preferably the heated bed is heated to a temperature corresponding approximately to the temperature in the laminator, the heater bed may include passageways through which a vacuum is applied to draw the base facer to the surface of the heater bed.

3. 4. A method as claimed in any preceding claim including the step of confining the side edges of the foam in the laminator, preferably the laminator includes a lower slatted laminator conveyor and the slats of the conveyor are provided with edge flights to confine the side edges of the board in the laminator, the method may include the step of leading the polymeric board from the laminator through an insulated tunnel prior to cutting of the board to length, preferably each stream of liquid foam reactants is delivered onto the preheated base facer from an independent outlet nozzle.

4.

5. A rigid polymeric insulating board whenever manufactured by a method as claimed in any preceding claim.