WO2013121189A1

WO2013121189A1 - Recycling of carpets

Info

Publication number: WO2013121189A1
Application number: PCT/GB2013/050322
Authority: WO
Inventors: Paul Harper; Robert Harper
Original assignee: Eco2 Enterprises Llp
Priority date: 2012-02-13
Filing date: 2013-02-13
Publication date: 2013-08-22
Also published as: WO2013121189A9; GB201202390D0; GB2499468A; GB201207216D0; GB2500742B; GB201218890D0; GB2499468B; GB2500742A

Abstract

A method of recycling carpet into structural beams or sheet materials having a laminated structure (10), the method comprising the steps of stacking at least two sheets of carpet (16) on top of each other to form a stack and bonding the faces of adjacent sheets of carpet in the stack to one another using an adhesive (16), the said adhesive (16) comprising any one or more of the group comprising: PVA; an emulsifier; and polyurethane and, once cured, cutting (28) the resulting laminate to desired dimensions. The resulting laminated material can be used as a substitute for building materials such as MDF sheeting, wooden beams and the like. Optionally, a relatively open, shock-absorbing laminate (40) can be manufactured having a non-slip surface (46), which may be suitable for use as an equine walkway.

Description

Title: Recycling of carpets

Description:

This invention relates to recycling, and in particular, but without limitation, to recycling of used carpets.

Carpets wear out and, thus, have a finite life. At the end of their useful life, many carpets are disposed of in landfill owing to their inherently difficult recyclability. Carpets are difficult to recycle because they generally comprise a mixture of materials, that is to say, a backing material, which can be a woven fabric, a felt or polymer foam, and a pile affixed to the backing material, which can be manufactured from a range of natural or synthetic materials. Because of the wide range of materials that are used in the manufacture of carpets, it is inherently difficult to classify them by type (one of the prerequisites for efficient recycling) by visual inspection. Moreover, recycling is made more difficult by the fact that the carpets' constituent parts are difficult to separate - an inherent feature of an item that is designed to be hardwearing. As such, the recycling possibilities for used carpets tend to be very limited, which leads to very low recycling rates compared to other items.

Nevertheless, it is known to recycle carpets by shredding them and by incorporating the shredded carpet material into a binder to form a composite material. For example, used carpets can be granulated using a shredder that cuts the carpet into small pieces, typically from a few millimetres to around 3 cm in size. Small, cut pieces of carpet can then be blended with an adhesive or thermoplastic polymer, prior to being moulded or formed into sheets or blocks. A significant problem with such a known recycling technique, however, is that carpet is designed to be a very tough and hard-wearing material, which makes it very difficult to granulate and cut. In particular, the tool wear rate of a carpet shredder can very high, and the throughput very low, making the carpet shredding step of the recycling process very uneconomic. Moreover, variations in the make-up of the constituent carpet pieces can lead to undesirable variations in end product, which can make the end product difficult to specify, thus reducing its market value.

Need therefore arises for an improved method of recycling used carpets.

According to a first aspect of the invention, there is provided a method of recycling carpet comprising the steps of stacking at least two sheets of carpet on top of each other to form a stack and adhering adjacent sheets of carpet in the stack to one another using an adhesive.

A second aspect of the invention provides a laminated material comprising a plurality of sheets of carpet overlaid to form a stack, and an adhesive interposed, and forming at least a partial bond, between adjacent sheets of the stack.

A third aspect of the invention provides a method of recycling carpet into structural beams or sheet materials having a laminated structure, the method comprising the steps of stacking at least two sheets of carpet on top of each other to form a stack and bonding the faces of adjacent sheets of carpet in the stack to one another using an adhesive, the said adhesive comprising any one or more of the group comprising: PVA; an emulsifier; and polyurethane and, once cured, cutting the resulting laminate to desired dimensions.

Advantageously, the invention removes the need to shred the carpet, which enables the recyclability of the carpet to be improved. In particular, by removing the shredding step, the amount of energy required to form the resultant material can be significantly reduced, a process step can be removed, and the amount of tooling required can be reduced.

Because the invention makes use of sheets of carpet, as opposed to shredded carpet pieces, the mechanical and physical properties of the resulting material can be more homogeneous, and there can also be less variation in properties from batch to batch.

In the context of the invention, the term "sheets" of carpet means relatively large sheets of carpet, for example, having width and/or dimensions exceeding 500mm, and preferably exceeding 1000mm. In a preferred embodiment of the invention, the sheets of carpet in the stack have a width of about, or greater than 48 inches, or ~1220mm and a length of about, or greater than 96 inches, or ~2440mm.

After having been formed, the resulting sheet material can be cut or trimmed to standard sizes corresponding to the standard sizes of existing building materials, such as 8' x 4' sheets, 2" x 2", or 2" x 4" cross-section beams, and so forth. By doing so, the invention can be used as, or specified as, a direct replacement for other, known building materials, such as sheet MDF, timber beams, and so on

The number of layers of carpet in the stack can comprise any plurality, and the carpet layers can be placed on top of each other in any desired orientation. For example, the carpet layers can be placed pile-to-pile, backing-to-backing and/or pile-to-backing. Individual layers can be placed in different orientations to yield desired mechanical properties.

The adhesive used to bind adjacent sheets of carpet in the stack can be of any suitable type. Preferably, the adhesive comprises a liquid curable adhesive, that is to say, an adhesive that can be applied in a flowable or liquid form and which cures or sets to form an adhesive bond between adjacent sheets of carpet. The adhesive bond can be any one or more of the group comprising: a chemical bond between the adhesive an each layer of carpet, a chemical bond facilitated by the adhesive that causes the adjacent sheets of carpet to bond to each other directly, or a micromechanical bond formed between the carpet layers or between a carpet layer and the adhesive layer.

The adhesive can be any one or more of the group comprising: PVA, an emulsifier and polyurethane, the latter being the preferred adhesive because it offers a great deal of versatility in its composition and mechanical properties, as shall be described below.

Preferred embodiments of the invention shall now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a table of different carpet types;

Figure 2 is a flow diagram illustrating, schematically, the method of the invention as applied to a two-layer laminated material;

Figure 3 is a schematic cross-section through a multi-layer laminated material in accordance with the invention; and

Figure 4 is a schematic cross-section through a multi-layer laminated material designed specifically for use in equine walkways.

Figure 1 is a table listing various permutations of carpets that may be recycled in accordance with the invention. The most difficult carpets to recycle are the wool-pile carpets and felt-backed carpets as these materials cannot be melted-down and are difficult to bond, respectively. The invention provides a solution to the difficulties associated with recycling all used carpet types, but in particular wool-pile carpets and felt-backed carpets, which have hitherto been un-recyclable or uneconomically recyclable. As shall be explained below, the invention aims to provide a sustainable recycling solution for:

recycling felt-backed carpets; recycling carpet types 3 to 14 of Figure 1;

recycling wool carpets; and

recycling any woven-backed carpet.

The method of the invention comprises the steps of stacking at least two sheets of carpet on top of each other to form a stack and adhering adjacent sheets of carpet in the stack to one another using an adhesive. Such a method is shown in Figures 2 to 4.

Referring now to Figure 2, the method is shown, schematically, in which, in step 1) a first sheet of carpet 10 is laid out on a flat surface 12. In step 2), and a liquid-curable, polyurethane adhesive 14 is applied and evenly spread across its pile 16 using, for example, a doctor blade 18. In step 3), a second sheet of carpet 20 is placed, pile-down, on top of the first sheet 10. In step 4), pressure P is evenly applied using platen press 22 (or by passing the two sheets through a pair of rollers (not shown)). Pressure P is applied to the carpet sheets 10, 20 whilst the polyurethane 14 is in a liquid or viscous state, which encourages the adhesive 14 to penetrate into the pile 16 and, optionally, to seep through the backing material 24. In addition, the pressure P causes the piles 16 to press into one another and interlock, with the adhesive 14 filling the gaps between the pile fibres. Pressure P is applied until the adhesive 14 has cured to ensure that the dimensions of the laminated sheet 20 thus formed remain within desired parameters. Once cured (step 5)), the resulting laminated sheet 26 is trimmed to desired dimensions using a cutting tool 28.

In Figure 3, the same procedure as described above is used to create a thicker laminated sheet 26, that is to say, a sheet 26 comprising four sheets of carpet 10, 20, 30, 32. In Figure 3 it will be noted that the carpet sheets 10, 20, 30, 32 have different orientations, specifically, being formed as two pile-to-pile stacks bonded backing-to-backing. Different layer orientations can be used, and the example of Figure 3 is purely exemplary. Because of the application of pressure P during the curing step, the adhesive 14 is able to penetrate the carpet pile 16 and the backing 24, thus enabling both woven and felt- backed carpets to be readily bonded together. Such a feature of the invention renders the method and resulting material 26 largely independent of the backing structures and materials of the various constituent carpets' sheets.

The use of polyurethane as the adhesive 14 has proven to be particularly advantageous because its properties can be altered by the appropriate selection of ingredients and applied pressure. For example, the viscosity of the liquid-state polyurethane can be reduced to encourage penetration into tightly matted felt backing materials, and the hardness of the polyurethane can be altered to yield stiffer or more flexible laminated materials 26, as desired. Temperature also plays an important role in the curing time and resultant properties of the polyurethane 14, as will be well-known to those skilled in the art.

On particular application of the invention is as a resilient, and/or shock-absorbing flooring material 40, as shown in Figure 4. In such a situation, water or moisture can be added to the liquid polyurethane 14 to cause it to foam during curing. The amount of foaming can be controlled by controlling the amount of water present, and the amount of expansion that occurs on foaming can be controlled by the appropriate application of pressure P (typically up to lONm^"2) during the curing process. By bonding adjacent sheets of carpet to one another using a foaming polyurethane, the resultant laminated material 40 can exhibit a cushioning effect.

In one particular embodiment of the invention, as shown in Figure 4, a multi-layer laminated material 40 has been formed by placing sheets of carpet backing-to-pile in an intended lower portion 42, with sheets of carpet pile-to-pile in an intended upper portion 44 thereof. By placing the upper sheets 44 of carpet pile-to-pile, the intended upper surface 46 of the resultant laminated material 40 is inherently cushioned because the piles of the upper sheets 44 can flex when point pressure is applied, whereas the intended lower portion 42 of the laminated material 40 provides a relatively stiff and inflexible portion, which is ideally suited to fixing to a solid sub-floor, such as a concrete walkway (not shown).

In Figure 4, it will be noted that the polyurethane adhesive 14 used in the lower portion 42 has a low water content, which inhibits foaming, thereby producing a relatively stiff base for the resulting material 40. However, the polyurethane adhesive 14 used in the upper portion 44 of the material 40 has water added to it to encourage it to foam during curing. As such, the density of the polyurethane adhesive 14 varies in different regions of the material, enabling the cushioning effect and backing rigidity of the resulting material 40 to be carefully controlled.

In Figure 4, it will also be noted that the intended upper surface 46 of the laminated material 40 has been overlaid with a non-slip surface coating 48, which comprises a layer of polyurethane 14 with grit, sand or other fine granular material 50 mixed into, or deposited on top of, it whilst the polyurethane 14 is in a liquid form.

The laminated material 40 of Figure 4 is particularly suited to use in equine walkways, where a cushioned, non-slip surface is required for horses, or other hooved, animals to walk on. As such, the laminated material 30 of the invention may be suitable as a flooring material in livery yards, stables, farmyards or on pathways frequented by shodden and/or hooved animals.

Test results indicate that the preferred polyurethane composition is Voramer (RTM) MR1060 manufactured by Dow Hyperlast, wcih comprises 70.0 - 90.0 % Prepolymer of MDI and polyol, 5.0 - 12.0% o-(p-lsocyanatobenzyl) phenyl isocyanate; diphenylmethane- 2,4'- diisocyanate, 5.0 - 12.0% Diphenylmethane-4,4'-di-isocyanate, and 1.0 - 5.0 % Diphenylmethane Diisocyanate, isomers and homologues.

During the trials, the amount of water added to cause foaming and to reduce the amount of polyurethane used (watering-down) was varied. The amount of water determined whether the polyurethane violently expanded and foamed during the cure and the homogeneity of the expansion. The deliberate addition of water alone tended to make the results unpredictable. Rather than varying the water content, therefore, the amount of activator was varied to control the foam expansion. Further, an oil polymer was used in place of water to act as a thinner to facilitate penetration of the polyurethane into the carpet structure. As a result, the foaming characteristics are managed purely through the inherent moisture content of the carpet and an element of polymer activator to eliminate uncontrolled foaming.

The invention is not restricted to the details of the foregoing embodiments, which are mere exemplary. In particular, owing to the versatility of the invention, materials having a range of properties can be formed, for example, relatively rigid sheets of the material can be used as direct replacements for timber, MDF or chipboard sheeting used in construction and/or joinery, cut beams of the material can be used in fencing and exterior joinery, or as structural elements in buildings and other constructions. Moreover, relatively "open" structured materials in accordance with the invention, that is to say, pile-to-pile sheets (with or without foamed adhesive), can be used in shock-absorbing applications, such as crash barriers, thermal and acoustic insulation applications, for example in walls of buildings. The range of applications for the invention is accordingly very broad. In particular, the invention may be used as a material for forming internal or external walls, dividing or partition walls, as a plasterboard replacement, as a thermal or acoustic insulation material, in walkways, building blocks and bricks, paving stones, screens, roofing panels, decking, doors, non-slip surfaces, balustrades, kerbs, driveways, garden walls and fence panels, railway sleepers, edgings, flooring, etc. Owing to the material's laminated structure, it can also be press- formed into relatively complex shapes, and could be used for steel panel replacements, single press boat molding, baths and the like.

Nevertheless, the invention aims to enable hitherto unrecyclable, or practically unrecyclable, materials to be re-used and/or recycled, thus potentially reducing landfill usage, wastage of materials, and reliance on "virgin" materials in the construction industry.

The following statements are not the claims, but relate to various aspects of the invention: Statement 1. A method of recycling carpet comprising the steps of stacking at least two sheets of carpet on top of each other to form a stack and bonding the faces of adjacent sheets of carpet in the stack to one another using an adhesive, the said adhesive comprising any one or more of the group comprising: PVA; an emulsifier; and polyurethane.

Statement 2. A laminated material comprising a plurality of sheets of carpet overlaid to form a stack, and an adhesive interposed, and forming at least a partial bond, between adjacent faces of sheets of the stack, wherein the said adhesive comprises any one or more of the group comprising: PVA; an emulsifier; and polyurethane.

Statement 3. A method or laminated material according to statement 1 or statement 2, wherein the sheets of carpet have width and/or length dimensions exceeding 500mm.

Statement 4. A method or laminated material according to any of statements 1 to 3, wherein the sheets of carpet have width and/or length dimensions exceeding 1000mm.

Statement 5. A method or laminated material according to any of statements 1 to 4, wherein the sheets of carpet have a width of, or greater than 1220mm and a length of, or greater than 2440mm. Statement 6. A method or laminated material according to any preceding statement, wherein after having been formed, the resulting sheet material is cut or trimmed to standard sizes corresponding to the standard sizes of existing building materials.

Statement 7. A method or laminated material according to any preceding statement, wherein any two carpet layers are placed on top of each other pile-to-pile.

Statement 8. A method or laminated materials according to any preceding statement, wherein any two carpet layers are placed on top of each other backing-to-backing,

Statement 9. A method or laminated material according to any preceding statement, wherein any two carpet layers are placed on top of each other pile-to-backing.

Statement 10. A method or laminated material according to any preceding statement, wherein the adhesive comprises a liquid curable adhesive.

Statement 11. A method or laminated material according to statement 10, wherein the adhesive is applied in a flowable or liquid form and cures or sets to form an adhesive bond between adjacent sheets of carpet.

Statement 12. A method or laminated material according to statement 11, wherein the adhesive bond can be any one or more of the group comprising: a chemical bond between the adhesive an each layer of carpet; a chemical bond facilitated by the adhesive that causes the adjacent sheets of carpet to bond to each other directly; and a micromechanical bond formed between the carpet layers or between a carpet layer and the adhesive layer.

Statement 13. A method according to any of statements 1 or 3 to 12, in which a first sheet of carpet is laid out on a flat surface and a liquid-curable, polyurethane adhesive is applied and evenly spread across its pile, a second sheet of carpet is placed on top of the first sheet.

Statement 14. A method according to statement 13, further comprising the step of applying inward pressure to the sheets of carpet.

Statement 15. A method according to statement 14, wherein pressure is applied using a platen press and/or by passing the laminated material through a pair of rollers. Statement 16. A method according to statement 14 or statement 15, wherein pressure is applied to the carpet sheets whilst the adhesive is in a liquid or viscous state and is applied until the adhesive has cured.

Statement 17. A method according to any of statement 14 15 or 16, further comprising the step of, once the adhesive has cured, trimming the laminated sheet to desired dimensions.

Statement 18. A resilient and/or shock-absorbing flooring material according to any of statements 2 to 17, wherein the adhesive comprises foamed polyurethane.

Statement 19. A method according to any of statements 1 or 3 to 18, further comprising the step of adding water to a liquid-curable polyurethane adhesive.

Statement 20. A method or laminated material according to statement 18 or statement 19, when dependent on any of statements 15 to 17, wherein the amount of foaming is controlled by controlling the amount of water added and the amount of expansion occurring on foaming is controlled by the appropriate application of pressure during the curing process.

Statement 21. A laminated material according to any of statements 2 to 20, comprising a first portion comprising sheets of carpet laid backing-to-pile and a second portion comprising sheets of carpet laid pile-to-pile.

Statement 22. A laminated material according to any of statements 2 to 21, further comprising a non-slip surface coating disposed on an exterior surface thereof.

Statement 23. A laminated material according to statement 22, wherein the non-slip surface coating comprises a layer of polyurethane with grit, sand or other fine granular material mixed into it.

Statement 24. A laminated material according to statement 22, wherein the non-slip surface coating comprises a layer of polyurethane with grit, sand or other fine granular material deposited on top of it whilst the polyurethane is in a liquid form.

Statement 25. An equine walkway comprising a laminated material according to any of statements 18 to 24. Statement 26. A laminated material according to any of statements 2 to 25, having mechanical properties selected to provide a direct replacement for timber, MDF or chipboard.

Statement 27. A fence, wall or structural element formed from a laminated material according to statement 26.

Statement 28. A shock-absorbing, thermally insulative or acoustically insulative material comprising a laminated material according to any of statements 18 to 25.

Claims

Claims:

1. A method of recycling carpet into structural beams or sheet materials having a laminated

structure, the method comprising the steps of stacking at least two sheets of carpet on top of each other to form a stack and bonding the faces of adjacent sheets of carpet in the stack to one another using an adhesive, the said adhesive comprising any one or more of the group comprising: PVA; an emulsifier; and polyurethane and, once cured, cutting the resulting laminate to desired dimensions.

2. A method as claimed in claim 1, wherein the laminate is cut to have width and/or length

dimensions exceeding 500mm.

3. A method as claimed in claim 1 or claim 2, wherein the laminate is cut to have width and/or length dimensions exceeding 1000mm.

4. A method as claimed in any of claims 1, 2 or 3, wherein the resultant laminate has a width of, or greater than 1220mm and a length of, or greater than 2440mm.

5. A method I according to any preceding claim, wherein the resulting laminate is cut or trimmed to standard sizes corresponding to the standard sizes of existing building materials.

6. A method according to any preceding claim, wherein any two carpet layers are placed on top of each other pile-to-pile.

7. A method according to any preceding claim, wherein any two carpet layers are placed on top of each other backing-to-backing.

8. A method according to any preceding claim, wherein any two carpet layers are placed on top of each other pile-to-backing.

9. A method according to any preceding claim, wherein the adhesive comprises a liquid curable adhesive.

10. A method according to claim 9, wherein the adhesive is applied in a flowable or liquid form and cures or sets to form an adhesive bond between adjacent sheets of carpet.

11. A method according to claim 10, wherein the adhesive bond can be any one or more of the group comprising: a chemical bond between the adhesive an each layer of carpet; a chemical bond facilitated by the adhesive that causes the adjacent sheets of carpet to bond to each other directly; and a micromechanical bond formed between the carpet layers or between a carpet layer and the adhesive layer.

12. A method according to any preceding claim, in which a first sheet of carpet is laid out on a flat surface and a liquid-curable, polyurethane adhesive is applied and evenly spread across its pile, a second sheet of carpet is placed on top of the first sheet.

13. A method according to claim 12, further comprising the step of applying inward pressure to the sheets of carpet.

14. A method as claimed in claim 13, wherein pressure is applied using a platen press and/or by passing the laminated material through a pair of rollers.

15. A method as claimed in claim 13 or claim 14, wherein pressure is applied to the carpet sheets whilst the adhesive is in a liquid or viscous state and is applied until the adhesive has cured.

16. A method as claimed in any preceding claim, further comprising the step of adding water to a liquid-curable polyurethane adhesive.

17. A method as claimed in claim 16, wherein the addition of water causes the liquid curable

polyurethane to foam, the amount of foaming being controlled by controlling the amount of water added and the amount of expansion occurring on foaming being controlled by the appropriate application of pressure during the curing process.

18. A laminated structural beam or sheet material manufactured via the steps of stacking at least two sheets of carpet on top of each other to form a stack and bonding the faces of adjacent sheets of carpet in the stack to one another using an adhesive, the said adhesive comprising any one or more of the group comprising: PVA; an emulsifier; and polyurethane and, once cured, cutting the resulting laminate to desired dimensions..

19. A resilient and/or shock-absorbing flooring material manufactured via the steps of stacking at least two sheets of carpet on top of each other to form a stack and bonding the faces of adjacent sheets of carpet in the stack to one another using a liquid-curable polyurethane adhesive and, once cured, cutting the resulting laminate to desired dimensions, and method further comprising the step of adding water to the un-cured, liquid-curable polyurethane adhesive, the addition of water causing the liquid curable polyurethane to foam, the amount of foaming being controlled by controlling the amount of water added and the amount of expansion occurring on foaming being controlled by the appropriate application of pressure during the curing process.

20. A method as claimed in any of claims 1 or 3 to 19, further comprising the step of adding water to a liquid-curable polyurethane adhesive.

21. A laminated material according to any of claims 18 to 20, comprising a first portion comprising sheets of carpet laid backing-to-pile and a second portion comprising sheets of carpet laid pile- to-pile.

22. A laminated material as claimed in any of claims 18 to 21, further comprising a non-slip surface coating disposed on an exterior surface thereof.

23. A laminated material as claimed in claim 22, wherein the non-slip surface coating comprises a layer of polyurethane with grit, sand or other fine granular material mixed into it.

24. A laminated material as claimed in claim 22, wherein the non-slip surface coating comprises a layer of polyurethane with grit, sand or other fine granular material deposited on top of it whilst the polyurethane is in a liquid form.

25. An equine walkway comprising a laminated material as claimed in any of claims 18 to 24.

26. A laminated material as claimed in any of claims 18 to 25, having mechanical properties selected to provide a direct replacement for timber, M DF or chipboard.

27. A fence, wall or structural element formed from a laminated material as claimed in claim 26.

28. A shock-absorbing, thermally insulative or acoustically insulative material comprising a

laminated material according to any of claims 18 to 25.

9. A method or laminated material substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.