GB2076681A

GB2076681A - Making foam for use as insulation

Info

Publication number: GB2076681A
Application number: GB8116536A
Authority: GB
Original assignee: PLASMOR Ltd
Current assignee: PLASMOR Ltd
Priority date: 1980-05-29
Filing date: 1981-05-29
Publication date: 1981-12-09
Also published as: GB2076681B

Abstract

In the production of plastics foam material predetermined and controlled quantities of air, hardener, surfactant and a resin, are thoroughly mixed together, the hardener being atomised with the air prior to the resin and/or other constituents being introduced into the mixing process. The air and atomised hardener and the other constituents being passed initially through a first shaped passageway 14 so as to obtain further mixing and laminar flow of the air and hardener, the resin and/or surfactant being supplied through a port 6 and subsequently induced into the flowing mixture by a Venturi 16. <IMAGE>

Description

SPECIFICATION Production of foam material This invention relates to the production of foam material and is particularly concerned with an improved method of and apparatus for producing foam material primarily for use as an insulation.

One method of producing foam makes use of apparatus which is a tube partially filled with glass balls known as Ballotini apparatus into one end of which the constituent parts used to make the foam are fed and in passing through are mixed.

After passing through the apparatus the resultant foam emerges from the opposite end of the tube.

Disadvantages of the use of a foam producing tube with Ballotini apparatus are problems due to unsatisfactory mixing and reaction of the constituents and the equipment quite quickly and easily becomes clogged thus making further use of the apparatus impossible until it has been cleaned.

Dismantling, cleaning, and re-assembly of the tube with Ballotini apparatus is very time consuming, and as a result is expensive due to the 'down time' of the apparatus.

A further and major problem with the use of the tube with Ballotini apparatus is concerned with the shrinkage of the resultant foam. It is thought that the shrinkage is due to the mixing process not being thorough enough and the present invention seeks to obviate this and other known disadvantages by providing an improved method and apparatus for use in the production of foam.

According to a first aspect of the present invention, there is provided a method for the production of foam material comprising the steps of thoroughly mixing together predetermined and controlled quantities of air, a hardener, a surfactant and a resin, said hardener being atomised with the air prior to said resin and/or said other constituents being introduced into the mixing process, the said air and atomised hardener and the other constituents being passed initially through a first shaped passageway so as to obtain further mixing and laminar flow of said air and hardener, said resin and/or said surfactant being introduced into the mixture by a Venturi effect produced by the shape and design of the apparatus. The mixture of air, surfactant, hardener and resin is passed through a second shaped passageway which causes further mixing thereof before entering a discharge tube.The constituents will be mixed together without the use of mechanical means.

Preferably the hardener will be in liquid form so as to enable atomisation to take place.

Alternatively the hardener may more preferably be in the form of gas (e.g. Hydrogen Chloride). The air and the liquid hardener (pre-atomised or gas) in controlled quantities will preferably be inserted into the apparatus initially through seperate inlets and will then be passed together through the said first shaped passageway so as to further mix the air and the hardener and so as to result in laminar flow to initiate the Venturi effect in the apparatus for the resin to be induced into the apparatus.

The resin will preferably be in the form of a liquid or slurry or suspension and will be induced into the apparatus under flow regulated conditions and will be inserted so that it is mixed with the mixture of air and hardener at or close to the exit point of the first shaped passageway, the total mixture then passing through said second shaped passageway which occasions the Venturi effect of the apparatus and which further mixes the constituents before finally passing through an expanding tube to emerge as foam from an orifice of the apparatus. The surfactant will preferably be pre-mixed with the resin so that it is introduced simultaneously therewith.

According to a second aspect of the present invention, there is provided apparatus for use in the manufacture of foam material comprising generally a tubular member having appropriate inlets for the constituent parts of the foam to be introduced into the apparatus, said apparatus including a first shaped passageway in which two constituent parts used to make the foam material are thoroughly mixed together, and a second shaped passageway through which the total admixture passes prior to entering an expanding tube from which the admixture leaves the apparatus as foam.

The first shaped passageway will preferably be in the form of a nozzle so that some of said constituent parts may be mixed and placed into laminar flow condition after being fed into the apparatus. The said shaping nozzle feeds a region of the apparatus into which the final constituent parts may be fed.

The second shaped passageway in combination with the effect of the first shaped passageway will also preferably be of a design to produce a Venturi effect so that the mixture leaving the first shaping nozzle will, after a zone where the final constituents are added, enter a restricting region with further mixing prior to entering the expanding tube and leaving the apparatus.

In order that the invention may be more readily understood an embodiment thereof will now be described, by way of example, reference being made to the accompanying diagrammatic drawing, the single figure of which is a sectional elevation of apparatus embodying the invention.

Referring to the drawing, the apparatus comprises a generally tubular member 2 having inlets 4 and 6 and a discharge outlet 20. The apparatus is preferably composed of metal.

Within the tubular member 2 and adjacent the inlet 4 is a member 10 which is threaded at 12 so that it may be releasably secured to and in the tubular member 2, and which includes a first shaped passageway in the form of a restriction and nozzle 14 to produce laminar flow. The member 10 will also preferably be composed of metal.

As will be seen from the drawing, that the tubular member 2 in its lower (in the drawing) region forms a second shaped passageway in the form of a restriction 1 6 to complete the Venturi effect of the apparatus and which communicates with expanding tube 1 8 and subsequently discharge 20.

It will be seen that the inlets 4 and 6 are internally screw threaded, flanged, or otherwise shaped so that the apparatus may be connected to constituent supply sources, not shown. A joint 8 is also screw threaded so as to enable easy connection with the expanding tube 1 8.

In use, air and hardener supply sources (not shown) are connected to the inlet 4, the hardener preferably being in liquid form for easy atomisation or as a gas (e.g. Hydrogen chloride), said air and hardener being initially mixed in controlled quantities prior to being fed in to the inlet 4. A resin in the form of solids suspended in water or a slurry or a liquid from a supply source (not shown) is connected to the inlet 6 and admitted with the surfactant into the interior of the tubular member 2 under flow regulated conditions. As the air and hardener pass through the apparatus they pass through the member 10 and consequently through the shaped passageway 14 so as to further mix the air and hardener and put the mixture under laminar flow conditions.

Thereafter the air/hardener mixture leaves the member 10 and enters a region 22 where it is initially mixed with the resin passing into the tubular member 2 through inlet 6.

The total constituents then pass toward the shaped passageway 1 6 which completes the Venturi effect and where they are further mixed together before entering the expanding tube 1 8 and leaving the apparatus through discharge outlet 20. The resin may be pumped in or sucked into the apparatus or a combination of both as preferred. The resin may contain filler or extender material as required, which can be introduced at any position in the mixing sequence.

It will be appreciated that the resin and surfactant may be introduced separately, if desired. Foam material produced in accordance with the invention may be formed in a flowable condition for use in cavity wall insulating applications or it may be formed into tiles or blocks or similar products. Alternatively where the foam material is in a flowable form the material may be incorporated into aggregate blocks so as to increase the thermal insulating properties of such blocks without reducing the overall strength of the blocks.

With a method and apparatus according to the invention the method is relatively simple to carry out and the apparatus is quickly and easily cleaned and stopped and started. A thoroughly mixed product is produced which is not susceptible or as susceptible to shrinkage and the reaction between the hardener and resin is controlled and occurs more evenly.

Claims

1. A method for the production of foam material comprising the steps of thoroughly mixing together predetermined and controlled quantities of air, a hardener, a surfactant and a resin, said hardener being atomised with the air prior to said resin and/or said other constituents; being introduced into the mixing process, the said air and atomised hardener and the other constituents being passed initially through a first shaped passageway so as to obtain further mixing and laminer flow of said air and hardener said resin and/or said surfactant being introduced into the mixture by a Venturi effect produced by the shape and design of the apparatus.

2. A method according to Claim 1, wherein the mixture of air, surfactant hardener and resin is passed through a second shaped passageway which causes further mixing thereof before entering a discharge tube.

3. A method according to Claim 1 or Claim 2, wherein the constituents are mixed together without the use of mechanical means.

4. A method according to any of Claims 1 to 3, wherein said hardener is in liquid form.

5. A method according to any of Claims 1 to 4, wherein the air and the hardener are inserted into the apparatus initially through seperate inlets, and are then passed together through the first shaped aperture so as to cause further mixing of the air and hardener and so as to result in laminar flow to initiate the Venturi effect for the resin to be induced into the apparatus.

6. A method according to Claim 5, wherein the resin is in the form of a liquid or slurry or suspension and is induced into the apparatus under flow regulated conditions, said resin being mixed with the mixture of air and hardener at or close to the exit point of the first shaped passageway.

7. A method according to Claim 6, wherein the mixture of air, hardener and resin pass through said second passageway which occasions the Venturi effect of the apparatus and which further mixes said air, hardener and resin, said mixture then passing to said expanding tube and thence to an exit of the apparatus.

8. A method for the production of foam material substantially as herein described.

9. Apparatus for use in the manufacture of foam material comprising generally a tubular member introduced into the apparatus, said apparatus including a first shaped passageway in which two constituent parts used to make the foam material are thoroughly mixed together, and a second shaped passageway through which the total admixture passes prior to entering an expanding tube from which the admixture leaves the apparatus as foam.

10. Apparatus according to Claim 9, wherein said first shaped passageway is in the form of a nozzle so that some of said constituent parts may be mixed and placed into laminarflow condition after being fed into the apparatus.

11. Apparatus according to Claim 10, wherein said shaping nozzle feeds a region of the apparatus into which the final constituent parts may be fed.

12. Apparatus according to any of Claims 9 to 11, wherein said second shaped passageway in combination with the effect of the first shaped passageway is of a design to produce a Venturi effect so that the mixture leaving the first shaping nozzle will, after a zone where the final constituents are added, enter a restricting region with further mixing prior to entering the expanding tube and leaving the apparatus.

13. Apparatus according to any of Claims 9 to 12, wherein said first shaped passageway is formed in a member which is releasably secured to and in said tubular member.

14. Apparatus according to any of Claims 9 to 13, wherein said expanding tube is releasably secured to said tubular member.

1 5. Apparatus for use in the production of foam material substantially as herein described with reference to and as illustrated in the accompanying drawing.

1 6. Foam material produced by the method as herein described.

1 7. Foam material produced by the apparatus as herein described with reference to and as illustrated in the accompanying drawing.