GB2096226A - Thermal insulation - Google Patents

Abstract

The invention provides a thermal insulation material consisting of particulate material adhered together at point of contact only so that it can be removed from a building cavity by suction but which has sufficient integrity to confer advantageous properties. Preferably the material is expanded polystyrene beads and the adhesive is an aqueous emulsion of a polymer or copolymer of vinyl acetate. Apparatus is provided for mixing the particles and liquid adhesive and for injecting same into a cavity, which operates at low pressure and which employs an airless spray for the adhesive. The apparatus can include an automatic ON/OFF valve in the supply line for the adhesive, preferably located at an outlet for the insulating mixture.

Description

SPECIFICATION Thermal insulation This invention relates to materials, apparatus and methods for cavity insulation in, for example, walls.

It is known to fill the cavity between the inner and outer walls of a house with loose expanded polystyrene beads and this material has found wide acceptance under the trade mark "DRI-FIL" for the thermal insulation of buildings. It possesses however the property of being extremely freeflowing so that any small holes in the cavity will allow the beads to flow out of the cavity.

Moreover if for any reason a window or the like is removed from a so-insulated wall e.g. for replacement purposes, all the insulation material above the level of the window will at once flow out of the cavity.

To overcome these disadvantages it has been proposed to mix the polystyrene beads with adhesive and thereafter to pump the heavily coated mixture into the cavity where it sets to form a relatively rigid structure. The apparatus required to mix and inject the mixture employs high pressure air from an air compressor and is expensive and complicated. This means that relatively unskilled operators are quite likely to use equipment improperly with consequent imperfect filling of the wall cavity. Additionally the relatively rigid mixture cannot be removed from the cavity should this become subsequently necessary.

According to a first aspect of the present invention there is provided a low pressure method of injecting a thermal insulating material into a cavity which comprises pumping dry particulate material along a pipeline, injecting a liquid adhesive into the pipeline downstream of the conveying means employing an airless spray nozzle therefor, and injecting the mixture of particulate material and adhesive into a said cavity.

Preferably the dry particulate material comprises expanded polystyrene beads, which may be spherical "virgin" beads or, preferably are more angular and irregular in shape, being "recovered" beads derived from waste expanded polyestyrene block or sheet. Other suitably lightweight particulate insulating materials may be employed such as vermiculite granules, chopped glass fibres or rock wool fibres.

Any suitable liquid adhesive may be employed but we have found emulsions containing polymers, e.g. copolymers of vinyl acetate, to be particularly suitable for the purposes of the present invention.

Very preferably the adhesive is used in an amount merely sufficient to cause very light adhesion of the insulating particles to each other, e.g. in the case of expanded polystyrene beads just to cause point contact between adjacent beads.

We have found that the material formed by the particles so adhered to each other has sufficient body to remain stable in situ under normal conditions but is still sufficiently mobile to be extractable from the cavity by application of powerful suction, should this subsequently be required.

The present invention has another aspect, therefore, the provision of an insulating material comprising thermally insulating particles adhered together at points of contact only and which is extractable from a cavity by application of suction thereto.

According to a third aspect of the present invention there is provided low pressure apparatus for supplying to a cavity particulate thermally insulating material which is partially coated with an adhesive which comprises a pipeline, conveying means for pumping a said particulate thermally insulating material along said pipeline, adhesive pressurizing means for pressurizing a supply of liquid adhesive and airless spray means downstream of the conveying means for introducing the pressurized liquid adhesive in a controlled amount into the pipeline thereby to cause the particulate thermally insulating material to adhere together whilst still permitting the adhesive/material mixture to travel down said pipeline to an outlet, which may be an injection nozzle, for injecting the mixture into a said cavity of a building.

Preferred embodiments of the materials, apparatus and methods of the present invention will now be described by way of Example only.

The outlet of a centrifugal fan (driven by a 3 or 4 HP electric or internal combination motor) having an inlet for admission of expanded polystyrene beads and suitably shaped impeller blades for pumping the beads, is connected to a 2" diameter transparent flexible pipe of the desired length. The blades may be scroll-shaped or may be radial blades mounted on a rotating disc.

The discharge end of the flexible pipe is connected to a 2" diameter steel tube with an adhesive injection inlet. The beads are thus drawn from a supply container and delivered into the steel tube at a pressure of approximately 2 Ib sq. in. (10" water gauge).

The apparatus for injecting the liquid adhesive comprises a pressurizable container for the liquid adhesive, an outlet af which is connected via a pressure control valve to an 8 mm diameter flexible supply line for supplying the adhesive to the steel tube. The supply line is connected via an inline fiiter, and a pressure gauge to a 4" diameter brass or copper pipe. The brass pipe is in communication with a low pressure, airless, atomizer jet having an atomizing orifice of 0.8 mm diameter. At the outlet of the steel tube an injection nozzle is provided which tapers to a diameter of 40 mm. The jet is located coaxially of the outlet of the steel tube and extends therealong to a position at which the injection nozzle begins to taper.

The container for the liquid adhesive may be pressurized manually but is fitted with a Schrader valve whereby a small portable air compressor of a capacity 2.5 cfm may be used for pressurization and the container is fitted with an integral pressure gauge. The flow of the adhesive is arranged to be from 240 to 280 cc per minute and is used in an amount of from 0.5 to 0.75 litres of adhesive per cubic metre of beads.

The adhesive employed is RESAD HA 2230/10 available from Resadhesion Ltd. It is a medium to high viscosity aqueous emulsion of a copolymer of vinyl acetate with 10% Veova 10 (Shell Chemical Co. Ltd.) or other equivalent material, stabilized with polyvinyl alcohol. It is diluted for use to a viscosity of 20 cps (Brookfield Spindle No.

2:20 rpm) and a green dye added.

The container containing the adhesive is pressurized to a pressure of 4 bar and the pressure control adjusted to give 25 psi at the in-line pressure gauge when at ground level.

The expanded polystyrene beads are "DRI-FIL" recovered or virgin beads having the following size distribution: Retained on 8 mm sieve: 0--8% by volume Retained on 5.6 mm sieve: 1040% by volume Retained on 2.8 mm sieve: 5080% by volume Passing 2.8 mm sieve: 12% by volume The amount of adhesive thus supplied to the beads is sufficient to cause adhesion between the beads merely at their points of contact, the adhesive not filling any of the interstices between the beads nor detracting from the advantageous properties of similar unadhered beads. Because only point of contact adhesion occurs the beads can, if the occasion arises, be removed from the wall cavities into which they have been injected by suitable disturbance and application of suction.

It has been found that the pressure in the container can very easily be maintained by occasional manual pressurizing. Only a minimum amount of specialized equipment is required in contrast to prior art systems and consequently operator training is very simple and does not call for high technical knowledge or ability.

In a first embodiment of the apparatus of the invention a manually operable ON/OFF lever was provided adjacent the injection nozzle to control the supply of adhesive. Although this is satisfactory it does require the presence of an operative at the injection nozzle and thus, to replenish the supply of beads, either the interruption of the insulating operation when a single operative is employed, or the presence of a second operative.

In a modification of the apparatus, therefore, a solenoid ON/OFF valve is provided at or adjacent the injection nozzle, in the adhesive supply line and which is operable from the head impeller position, i.e. from the ground. Most preferably the valve is operated from a position adjacent the bead supply station (i.e. adjacent the inlet to the fan). In practice we prefer to arrange for the valve to be automatically switched ON when the bead impeller is actuated. Although the solenoid valve is designed to fail OFF it is still preferred to include a manually operable valve adjacent the injection nozzle in case of a breakdown or to cut off supply of adhesive even when beads are still being supplied. Such a manual valve can be locked into its ON or OFF position.

It will be clear that the remotely operable valve need not be a solenoid valve but may be pneumatic, hydraulic or electrical as required for any particular application. The valve may be actuable in accordance with a sensed flow of beads in the bead supply line, such sensing being, for example photoelectric in nature.

It will be appreciated that in addition to greatly improving the known thermal cavity insulation techniques, the techniques described in the present application will be applicable to any other art in which it may be necessary to adhere particles lightly together.

Claims (28)

1. A low pressure method of injecting a thermal insulating material into a cavity which comprises pumping dry particulate material along a pipeline, injecting a liquid adhesive into the pipeline downstream of the conveying means employing an airless spray nozzle therefor, and injecting the mixture of particulate material and adhesive into a said cavity.

2. A method according to Claim 1, wherein the dry particulate material comprises expanded polystyrene.

3. A method according to Claim 1 or 2, wherein the liquid adhesive comprises an emulsion containing a polymer or copolymer of vinyl acetate.

4. A method according to any preceding Claim, wherein the dry particulate material is supplied at a pressure of approximately 10" water gauge.

5. A method according to any preceding Claim, wherein the liquid adhesive is supplied at an initial pressure of approximately 25 psi gauge.

6. A method according to any preceding Claim, wherein the liquid adhesive is supplied in an amount reiative to the particulate material sufficient merely to adhere together the particles of particulate material at points of contact only.

7. A method of injecting a thermal insulating material into a cavity, substantially as hereinbefore described.

8. A thermal insulation material comprising thermally insulated particles adhered together at points of contact only and which is extractable from a cavity by application of suction thereto.

9. A material according to Claim 8, wherein the particulate material comprises beads of expanded polystyrene.

10. A material according to Claim 8 or 9, wherein the particles are adhered together by means of an adhesive comprising a polymer or copolymer of vinyl acetate.

11. A thermal insulation material substantially as hereinbefore described.

12. A low pressure apparatus for supplying to a cavity particulate thermally insulating material which is partially coated with an adhesive which comprises a pipeline, conveying means for pumping a said particulate thermally insulating material along said pipeline, adhesive pressurizing means for pressurizing a supply of liquid adhesive and airless spray means downstream of the conveying means for introducing the pressurized liquid adhesive in a controlled amount into the pipeline thereby to cause the particulate thermally insulating material to adhere together whilst still permitting the adhesive/material mixture to travel down said pipeline to an outlet, which may be an injection nozzle, for injecting the mixture into a said cavity of a building.

13. Apparatus according to Claim 12, wherein said pipeline is transparent and flexible.

14. Apparatus according to Claim 12 or 13, wherein said conveying means comprises an impeller arranged to be driven electrically or by means of an internal combustion engine.

1 5. Apparatus according to Claim 14, wherein said impeller includes a centrifugal fan having scroll shaped impeller blades.

16. Apparatus according to Claim 14, wherein said impeller includes a centrifugal fan having radial blades affixed to a rotatable disc.

17. Apparatus according to any of Claims 12 to 16, wherein said adhesive pressurizing means comprises a tank for the liquid adhesive which tank is manually pressurizable and/or pressurizable by means of an external source of compressed air.

18. Apparatus according to any of Claims 12 to 17, wherein said airless spray means comprises an atomizer nozzle located in the flow path of the particulate material.

1 9. Apparatus according to Claim 18, wherein the outlet is an injection nozzle.

20. Apparatus according to Claims 1 8 or 19, wherein the injection nozzle is of tapering form and the atomizer nozzle is located coaxially of the injection nozzle at the point at which it commences its taper.

21. Apparatus according to any of Claims 12 to 20, wherein a manually operable ON/OFF valve is fitted in the supply line for the liquid adhesive, at or adjacent the injection nozzle.

22. Apparatus according to any of Claims 12 to 21, wherein an automatically operable ON/OFF valve is fitted in the supply line for the liquid adhesive, at or adjacent the injection nozzle.

23. Apparatus according to Claim 22, wherein said valve is a solenoid valve.

24. Apparatus according to Claim 22 or 23, wherein said valve is arranged to switch ON when the conveying means for pumping the particulate material is switched on.

25. Apparatus according to Claim 22 or 23, wherein sensing means is provided for sensing flow of particulate material and for switching ON said valve when said flow is sensed and for switching it OFF when said flow ceases.

26. Apparatus according to Claim 25, wherein said sensing means includes a source of electromagnetic radiation and a photoelectric detector therefor.

27. Low pressure apparatus for supplying to a cavity a particulate thermally insulating material which is partially coated with an adhesive, substantially as hereinbefore described.

28. The features hereinbefore disciosed, or their equivalents, in any novel selection.