Introduction

The invention relates to a polymeric insulating foam board of the type comprising upper and lower facers with an insulating foam core therebetween. Such boards are widely used for insulation of walls and roofs of buildings.

One of the problems with manufacture of such boards, is that a large amount of waste boards can be generated due to various problems that can arise during manufacture of the boards. Currently such waste boards must be disposed of leading to substantial waste disposal costs. Such disposal is environmentally undesirable.

There is therefore a need for a system to alleviate at least some of these problems.

Statements of Invention

According to the invention there is provided an insulating foam board comprising a first facer, a second facer and an insulating foam core between the first and the second facers, the insulating foam core comprising a main foam body and a recycled foam portion within the foam body.

Preferably the recycled foam portion is of substantially the same formulation as that of the main foam body.

The insulating core may be a polyisocyanurate foam core or a phenolic foam core.

In one embodiment the recycled foam portion comprises a plurality of foam pieces. The foam pieces may have an average dimension of from 5 to 25mm, typically from 10 to 15mm.

In one case the foam pieces comprise pellets.

In another embodiment the recycled foam portion comprises a block or briquette.

In one embodiment the recycled foam comprises fine ground pieces which are preferably of a small size suitable for delivery into a mixing head for foam reactants.

In another aspect the invention provides 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:

leading a base facer to a lay-down area;

laying liquid foam reactants onto the base facer;

leading an upper facer over the foam reactants;

leading the sandwich thus formed into an oven;

characterised in that a recycled foam portion is introduced prior to heating of the assembly in the oven.

In one embodiment the method comprises delivering the recycled foam portion to the first facer and subsequently applying liquid foam reactants over the recycled foam portion.

The recycled foam portion may comprise a plurality of foam pieces which are introduced to the first facer. Alternatively the recycled foam portion comprises a block or briquette which is introduced to the first facer. In this case the method may comprise the step of applying an adhesive means to at least portion of the fist facer and the block is applied to the adhesive means.

In one embodiment the method comprises delivering the recycled foam reactants into the liquid foam reactants. In one case the liquid foam reactants are passed through a mixing head and the recycled foam portion is introduced into the mixing head.

The liquid foam reactants may be laid down in a plurality of spaced-apart streams onto the base facer.

The oven may comprise a laminator having upper and lower laminator conveyors, the upper laminator conveyor checking the rise of the foam and preventing over- expansion.

The invention also provides an insulating foam board when manufactured by a method of the invention.

Brief Description of Drawings

The invention will be more clearly understood from the following description thereof give by way of example only with reference to the accompanying drawings in which :-

Fig. 1 is a side view of an apparatus used to manufacture a foam board according to the invention;

Fig. 2 is a cross sectional view of a laminator part of the apparatus;

Fig. 3 is a perspective view of apparatus for delivering recycled foam; and Fig. 4 is an elevational view of the apparatus of Fig. 3.

Detailed Description

The invention provides a method for manufacturing a rigid polymeric insulating foam board comprising a lower facer 1, an upper facer 2 and a foam layer 3 between the facers.

The upper and lower facers 1, 2 may be of the same or different flexible materials.

For example the or each facer may be of a paper, foil, glass fibre, plastic or any other suitable material or laminate of two or more of such materials.

The foam 3 may be of any suitable type including a polyurethane, polyisocyanurate or phenolic foam formed from appropriate reactant ingredients.

Referring particularly to Fig. 1, 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 oven 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 may be preheated by leading the facer 1 over a heated bed 30 which is heated to a temperature of from 35 to 85 ⁰ C. In this case the heated bed 30 comprised 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 the liquid foam reactants are led are located at the downstream end of the second heater bed section 30b. Each of the heater bed sections 3Oa ₅ 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 between 50°C and 6O ⁰ C, depending on the facer and line speed, 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 stream across the facer. The facer 2 is also preheated by passage through portion of the laminator 10 which is typically between 35 ⁰ C and 70 ⁰ C, in one case about 6O ⁰ C, prior to application to the foam. Because the facer 1 is preheated to the prepolymer reactants delivered through the nozzles 9 can be relatively cool which maximised 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.

Referring to Fig. 2 the laminator 10 comprises an upper conveyor 50 and a lower 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 flight 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 recycled foam portion is of substantially the same formulation as that of the main foam body and is produced as follows. There are some foam boards that are rejected for various reasons, for example because they do not meet manufacturing specifications, are damaged in handling, transit or on site. In the invention such waste boards are shredded to form shredded foam pieces which are generally irregular in shape and may have an average dimension of 5mm to 25mm, ideally about 10 to about 15mm.

In one case shredded foam pieces 25 are directly incorporated into the board. The level of incorporation/inclusion can be selected to meet specification requirements and may for example be from very low levels such as 1% to high levels such as 50% or possibly more.

The foam pieces may be applied between fixed head lay-down streams and a main lay- down head. The lay-down streams would then meet up capturing the foam pieces. Alternatively the foam pieces are deposited after foam lay-down. After the lay-downs on board, the top facer comes down and the product is essentially doctored (or squashed) which has the effect of squeezing the foam pieces into final position. The foam pieces have no sharp edges so would not penetrate or perforate the facer.

In the invention the recycled foam portion may be introduced prior to lay-down of liquid foam reactants to ensure that the recycled foam portion is integrated into the main foam body.

In another embodiment of the invention the recycled foam may be ground down to a fine size. The finely ground foam pieces may then be delivered into a mixing head for foam reactants and the liquid foam reactants laid down on the facer comprises the recycled foam portion.

Referring to Figs. 2 and 3, in one foam board according to the invention the recycled foam portion is in the form of multiple recycled foam pieces which are delivered from a supply hopper through a screw conveyor 41 feeding open nozzles or chutes 42 which deposit the foam pieces onto the facer 1. In this case the conveyor 41 delivers the scrap foam pieces into a hopper 43 with two outlets 44, one associated with each outlet nozzle chute 42. The foam pieces flow by gravity through flexible conduits 45. The arrangement ensures minimum risk of blockage of the chutes 42. In addition, vibration applying elements may be mounted on the chute outlets 42 to further ensure the free flow of foam pieces. As a further precaution a vision system may also be used to monitor the flow of foam pieces. A pre-lay-down foam/adhesive layer may be applied on top of the exposed surfaces of the facer 1 and, if desired over the deposited foam pieces. The inclusion of a pre-lay-down adhesive/foam assists in retaining the foam pieces. On lay-down of liquid foam reactants over the foam pieces, the pieces become mobile and are integrated into the liquid foam and ultimately are dispersed in the foam core 3.

A binder may be used which is provided either on the facer 1 in advance of foam lay- down and/or applied to the foam pieces. Alternatively, a fixed head may be used to ^a Pply ^a layer over the foam pieces, hi another arrangement the foam pieces may be added after the main foam lay-down so that the foam is captured in the reacting foam mixture and is dispersed in the foam matrix.

Any suitable binder may be used in forming the foam pieces into pellets or briquettes. The pellet forming process may involve one or more of heat or pressure during moulding.

There are several advantages of the invention. Waste is re-used leading to a reduction in disposal costs and reduction in manufacturing costs.

This technology can also be applied to recycle boards used in old buildings. Such a recycle stream may be used separately or in admixture with a recycling stream of production boards.

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