GB1569217A - Glass fibre recovery - Google Patents

Description

(54) GLASS FIBRE RECOVERY (71) We, POLYCYL (ENGINEER ING) LIMITED, a British Company, of 3 Christchurch Bay Road, New Milton, Hampshire BH25 7NT do herebv declare the invention, for which we pray that a patent may be granted to us. and the method by which it is to be performed. to be particularly described in and bv the follow mg statement: This invention relates to a process for the recovery of glass fibres from waste fibre material resulting from the production of glass fibre reinforced plastics ('GRP') products.

Glass fibres are commonlv supplied to manufacturers of GRP moulded products such as boatbuilders and small-scale motor vehicle manufacturers and for building and industrial applications in the form of rolls of non-woven mat in which individual bundles of glass fibres or filaments of up to or mahout 2 inches long are held together by a binder.

In the manufacture of a moulded product.

the pieces of mat are cut to shape. using patterns where appropriate. the cut pieces are then liad up in the mould and a polyester, phenolic or epoxide resin is applied thereto. However. the cutting operation normally leaves 1()% or more of the original roll as offcuts which are discarded.

Furthermore, the cut pieces of mat normally protrude beyond the edges of the mould.

and after application and curing of the resin the moulding has to be trimmed to shape.

The trimmings from completed mouldings often also include significant areas not contacted bv the resin. in which areas there are glass fibres available for recovery. Despite the significant amount of waste being produced by users of glass fibres there is at the present time no significant programme for recovery of glass fibres from offcuts and trimmings.

The present invention provides a process for recovering glass fibres from a piece of non-woven glass fibre mat which comprises agitating the piece of glass fibre mat in contact with water or a mixture of water with an organic solvent and/or other additive to at least reduce the effectiveness of the binder in holding the mat together and at least partiallv break down the mat into individual fibres or fibre bundles. recovering the glass fibres or fibre bundles from the water or mixture. and drying the glass fibres or fibre hundles.

It has been tound that the cohesion between groups of glass tibres stabilised into a mat. as is conventional in the art. bv means of a binder which may be for example an emulsion binder applied eg by spraying or other type of chemical or resin binder, including a binder in powder form. can be reduced significantly on immersion of the mat in water or a mixture comprising water nnd an organic solvent and/or other additive and that partial or complete breakdown of the mat into its component fibres or fibre bundles can be brought about by agitation of the mat tor example mechanically as by contra-rotating spikes or paddles immersed in the water or mixture. The glass fibre waste material may be subjected to initial soaking before the agitation step.After the pieces of the mat have been broken down to the extent required for their intended use.

the resulting glass fibre material is removed from the water or mixture and dried. These operations are convenientlv carried out in apparatus which in a preferred form comprises a tank having a perforated inner liner or tray-like member with a perforated bottom. which can be lifted out and which is etfective to separate and withdraw the glass fibre bundles which can then be dried by means of environmentallv controlled storage. for example bv means of warm air drying or by means of heated plates or moulds. The liner or trav may have perforated or unperforated plates to promote the removal of water or mixture from the separated glass fibres or fibre bundles.

When the material from which the glass fibres are being recovered is trimmings from completed mouldings, an additional centrifugation, filtering or settling step may be required to separate the resin-bonded portions of the trimmings from the suspension of glass fibres or fibre bundles.

Immersion in cold water is normally adequate to enable the mat to be broken down into the individual fibres within each bundles, but the water may be heated if desired. A surfactant and/or an additive for facilitating breakdown of the mat may be present, but in this case rinsing of the fibres withdrawn from the water may be required because surfactant or additive remaining on the surface of the recovered glass fibres may impair the qualitv of a moulded GRP product made therefrom.

The additive in the mixture may comprise an emulsifying or de-emulsifying agent according to requirements and the varying stages in the process.

The physical nature of the recovered glass fibres can be varied in accordance with their intended end use by varying the conditions under which they are dried and by application of pressure during drying. Where the agitation has been continued until substantially complete breakdown of the pieces of mat has occurred and pressure is not applied during drying. the product is of high bulk and low density. It is not readily applicable to manual lay-up moulding techniques such as are used in boat-building but it can be used in pressure moulding processes. A more compact product can be obtained bv application of heat and pressure during drying. any residual binder on the bundles of fibres helping to hold the fibres together.

Separated fibre bundles withdrawn from the water or mixture after the agitating step has been completed can convenientlv be converted into a compacted product by centrifugation filtering and/or settling followed bv drying under heat and pressure. for example by drying between heated plates or by passage through rollers.Appropriate variation of the drving conditions and the degree of separation of the fibre bundles in the initial agitation step together with application of pressure where necessarv can be used to produce a range of recovered glass fibre material which can include: (a) largely separated glass fibres suitable for spray or compound moulding: (b) largelv or partly separated glass fibres suitable for compound or press moulding and (c) pre-formed shaped articles or glass mat-like materials produced bv drying under pressure with addition of additives or binding agents if required.

The weight of glass fibres per unit area of these recovered products may be controlled by means of appropriate volume and/or weight control methods.

In some cases it may be helpful to incorporate light open-weave glass or other fibrous layers on one or both sides of the recovered glass fibre material either before or after the drying operation to assist in the handling and subsequent processing of the material. and/or to introduce an additional amount of binding material in some cases.

Apparatus for carrying out the process according to the invention will now be described bv wav of example with reference to the accompanying single Figure which shows a diagrammatic cross-sectional side view of the apparatus.

Referring to the drawing. apparatus for recovering glass fibres from pieces of nonwoven glass fibre waste material comprises a hopper l for receiving the glass fibre waste material 2. which as mentioned above may be either offcuts of glass fibre material or trimmings from completed mouldings. In the hopper I. the material 2 may be soaked with water or a mixture of water with an organic solvent and/or additive. as a preliminary step.

Disposed below the hopper I is a container 3 into which the material 2 can be passed from the hopper l. The container 3 includes a mechanical agitation assembly denoted generallv by reference 4. and comprising a multiplicitv of stationary vanes or blades fixed to the walls of the container 3. and a corresponding multiplicitv of movable blades carried bv a rotarv shaft 5. When the shaft 5 is driven in rotation bv its motor. the glass fibre material in water or the abovementioned mixture is agitated. whereby the material is broken down into individual fibres or fibre bundles.

Arranged at the bottom of the container 3 is a discharge opening controlled by a valve 6 which leads into a tank 7 in which the glass fibre or fibre bundles are separated from the water or the above-mentioned mixture. The tank 7 contains an inner liner or trav as indicated at 8. with a perforated bottom 9.

Thus. when the slurrv of broken-down glass fibre material and water or mixture passes into the tank 7 from the container 3. the water or mixture drains through the perforations in the perforated bottom 9 of the tray 8. leaving the glass fibre material in the tray 8. When the trav 8 is sufficientlv filled with collected glass fibre material. the tray 8 is lifted out for the subsequent operation of drying the collected glass fibre material.

Reference numeral l() denotes a pipe connected to the lowest part of the container 7 for discharge of the water or mixture which passes through the perforations in the bottom 9 of the tray 8. and reference 11 denotes a pump for recirculating the discharged water or mixture back into the top part of the container 3.

It will be seen that with the abovedescribed process waste glass fibre material such as offcuts and trimmings from production processes using non-woven glass fibre mat can be recycled and glass fibres recovered therefrom can be emploved in pressmoulding or other glass fibre production processes. WE CLAIM IS:- WHAT WE CLAIM IS: 1. A process for recovering glass fibres from a piece of non-woven glass fibre mat which comprises agitating the piece of glass fibre mat in contact with water or a mixture of water with an organic solvent and/or other additive to at least reduce the effectiveness of the binder in holding the mat together and at least partially break down the mat into individual fibres or fibre bundles, recovering the glass fibres or fibre bundles from the water or mixture. and drying the glass fibres or fibre bundles.

2. A process according to claim l wherein said glass fibre mat is agitated by mechanical agitator means.

3. A process according to claim I or claim 2 wherein said drying step is performed bv the application of heat to the glass fibres or fibre bundles.

4. A process according to claim l. claim 2 or claim 3 wherein a pressure is applied to the glass fibres or fibre bundles during the drying step.

5. A process according to anv one of the preceding claims wherein the water or mixture in which the piece of glass fibre mat is agitated is heated.

6. A process according to anv one of the preceding claims wherein said additive is a surfactant and/or additive for facilitating mat breakdown. and wherein the glass fibres or fibre bundles are optionally rinsed after recovery from said mixture.

7. A process according to any one of the preceding claims wherein a centrifugation.

filtering or settling step is performed before the recovery of glass fibres or fibre bundles from said water or mixture. thereby to separate any resin-bonded portions ot glass fibre mat from the suspension of glass fibres or fibre bundles in said water or mixture.

8. A process according to anv one of the preceding claims wherein the glass fibre mat is initiallv soaked in water or said mixture.

before the agitation step.

9. A process for recovering glass fibres from waste glass fibre material. according to claim 1 and substantiallv as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. denotes a pump for recirculating the discharged water or mixture back into the top part of the container 3. It will be seen that with the abovedescribed process waste glass fibre material such as offcuts and trimmings from production processes using non-woven glass fibre mat can be recycled and glass fibres recovered therefrom can be emploved in pressmoulding or other glass fibre production processes. WE CLAIM IS:- WHAT WE CLAIM IS:

1. A process for recovering glass fibres from a piece of non-woven glass fibre mat which comprises agitating the piece of glass fibre mat in contact with water or a mixture of water with an organic solvent and/or other additive to at least reduce the effectiveness of the binder in holding the mat together and at least partially break down the mat into individual fibres or fibre bundles, recovering the glass fibres or fibre bundles from the water or mixture. and drying the glass fibres or fibre bundles.

2. A process according to claim l wherein said glass fibre mat is agitated by mechanical agitator means.

3. A process according to claim I or claim 2 wherein said drying step is performed bv the application of heat to the glass fibres or fibre bundles.

4. A process according to claim l. claim 2 or claim 3 wherein a pressure is applied to the glass fibres or fibre bundles during the drying step.

5. A process according to anv one of the preceding claims wherein the water or mixture in which the piece of glass fibre mat is agitated is heated.

6. A process according to anv one of the preceding claims wherein said additive is a surfactant and/or additive for facilitating mat breakdown. and wherein the glass fibres or fibre bundles are optionally rinsed after recovery from said mixture.

7. A process according to any one of the preceding claims wherein a centrifugation.

filtering or settling step is performed before the recovery of glass fibres or fibre bundles from said water or mixture. thereby to separate any resin-bonded portions ot glass fibre mat from the suspension of glass fibres or fibre bundles in said water or mixture.

8. A process according to anv one of the preceding claims wherein the glass fibre mat is initiallv soaked in water or said mixture.

before the agitation step.

9. A process for recovering glass fibres from waste glass fibre material. according to claim 1 and substantiallv as hereinbefore described.