GB2548962A

GB2548962A - Process for the recycling of a waste material

Info

Publication number: GB2548962A
Application number: GB1701847.4A
Authority: GB
Inventors: Comforth Gary; Minnock Mark; Minnock Jenny; Ogden Gary
Original assignee: Jn1 Ltd
Current assignee: Jn1 Ltd
Priority date: 2016-02-03
Filing date: 2017-02-03
Publication date: 2017-10-04
Also published as: GB201701847D0; GB201601955D0

Abstract

The present invention relates to a process for the recycling of a waste material (e.g. waste paint or a by-product formed in the process of producing paint) and the uses for the resulting recycled composition. The process comprises the steps of drying a waste material recovered from a paint production process and processing the waste material into a particulate form. The recycled composition of the present invention is beneficial to the paint and carpet industries, and can be used in carpets, e.g. carpet adhesives or carpet backings, or paints.

Description

PROCESS FOR THE RECYCLING OF A WASTE MATERIAL

The present invention relates to a process for the recycling of a material typically sent to landfill and, more particularly, to a process for the recycling of a waste material from the paint production process into a useful material, such as a carpet adhesive and/or backing material.

Paint compositions and paint production processes are well-known and the production and distribution of paint is a global industry. A paint is essentially composed of several key ingredients. These include one or more pigments for colour, one or more solvents for ease of application, one or more resins for drying, and various additives. A common additive in paint is filler. Other additives can include dispersants, defoamers, binders, thickeners and biocides.

Paint is typically produced by a process utilising the following steps: (1) Fine grain pigments are premixed with resin, one or more solvents, and additives to form a paste. The resin can act as a wetting agent to moisten the pigment. (2) The paste mixture can then either be routed to a sand-mill or to a dispersion tank. a. In a sand mill, particles of sand or silica are agitated to grind the pigment particles, making them smaller and dispersing them throughout the mixture. The sand or silica particles are then filtered from the mixture. b. In a dispersion tank, the paste is subjected to a high-speed agitation by a circular blade on a rotating shaft.

It is more common for water-based latex paints to be processed in a high-speed dispersion tank. (3) The dispersed paste is then thinned in large kettles, where it is agitated with a preselected volume of solvent to provide a finished paint. The volume of solvent is dependent on the type of paint desired. (4) Finally, the paint is pumped into cans for distribution.

As part of the process of producing paint, a by-product comprising a mixture of the paint components results and is typically left as a residue on the apparatus used in the process. In current paint production methods, the by-product is washed from the containers, creating a waste effluent. Water is typically used to wash out the containers. The waste effluent obtained from the washing is typically filtered to reduce its water content. The resulting filter cake residue is collected, typically in a refuse skip, and sent to landfill.

In the current desire to reduce the environmental impact of waste material, there is a drive to reduce the amount of waste material sent to landfill. In the paint industry, there is a desire to adopt more environmentally friendly disposal methods, particularly methods that reduce or remove waste material being sent to landfill. However, there are at present very few commercially viable alternatives provided for paint manufacturers.

There is therefore a need in the industry to reduce the waste material sent to landfill. The present invention has been made with the above referenced considerations in mind.

According to a first aspect of the present invention, there is provided a process for the recycling of a waste material, the process comprising the steps of: (a) drying a waste material recovered from a paint production process; and (b) processing the waste material into a particulate form.

The waste material is recovered from the paint production process.

The waste material typically comprises a by-product formed in the process of producing paint. The by-product generally accumulates on the apparatus used in the paint production process, such as for example the walls of the dispersion tank. The by-product is typically removed from the apparatus by washing, preferably with water. This creates a waste effluent.

Thus, the waste material may be obtained by washing apparatus used in the paint production process with water to provide a waste effluent. This step is optional and is generally conducted as part of a typical industrial process by a paint manufacturer.

The waste effluent may be filtered to reduce or remove the water content to provide a residue comprising the waste material. Again, this step is optional and can be performed as part of an industrial process.

The waste material is typically obtained in the form of a filtration residue resulting from the filtration of the waste effluent. The filtration residue may be referred to herein as a filter cake.

Preferably, the waste material comprises the filter cake from the waste effluent. The filter cake can be obtained from paint manufacturers following the treatment of a waste effluent which is generated during the process of producing paint as described herein. Typically, the filter cake would otherwise have been sent to landfill.

The waste material may have a solids content of around 10 to 90%, preferably around 20 to 80%, and more preferably around 40 to 60% w/w.

The waste material may be in the form of a sludge or slurry.

The present invention utilises the waste material for subsequent processing into a desirable material. This avoids the material being sent to landfill, which has environmental advantages.

The waste material may comprise one or more of the ingredients or materials used in the paint production process. The waste material may comprise a mixture of such ingredients or materials.

The waste material may comprise a filler material used in the paint production process. Any unwanted, harmful or hazardous components present in the waste material may be separated from the filler material as desired or as appropriate.

The waste material may be a filler-based waste material. The term ‘filler-based’ is used herein to refer to a composition in which a filler material is the most abundant individual component.

The filler may be or contain a carbonate. The waste material may be carbonate-containing or carbonate-based. The term ‘carbonate-containing’ is used herein to refer to a composition in which a carbonate is a component. The term ‘carbonate-based’ is used herein to refer to a composition in which a carbonate component is the most abundant individual component.

The carbonate in the carbonate-containing or carbonate-based materials may comprise any carbonate material used as part of the paint production process. Carbonates, such as calcium carbonate, are typically used in the paint production process as fillers.

Typically, the carbonate is calcium carbonate.

As noted herein, the waste material may also comprise additional components used in the production of paint. Such components may be selected from the group consisting of water, additives, pigments, additional fillers, binders, thickeners, and biocides.

The additives may be present in the waste material in an amount of from 0.1-1.0 wt%, preferably 0.1-0.9 wt% and more preferably 0.1-0.8 wt% of the waste material. Typically, the additives constitute less than 1 wt% of the waste material. Suitable additives include oil-based and surfactant-based compounds.

The pigment may be present in the waste material in an amount of from 2-10 wt%, preferably 2-9 wt% and more preferably 2-8 wt% of the waste material. Typically, the pigment(s) constitute around 5 wt% of the waste material. Suitable pigments include, but are not limited to, titanium dioxide, organic pigments and inorganic dyestuffs.

The additional fillers may be present in the waste material in an amount of from 10-50 wt%, preferably 10-45 wt% and more preferably 10-40 wt% of the waste material. Typically, the additional filler(s) constitute around 30 wt% of the waste material. Suitable fillers include, but are not limited to inorganic and organic fillers such as aluminium silicates, diatomaceous silica, magnesium silicate and zinc oxide. Such fillers can comprise various particle sizes.

The binders may be present in the waste material in an amount of from 5-40 wt%, preferably 5-35 wt% and more preferably 5-30 wt% of the waste material. Typically, the binder(s) constitute around 10 wt% of the waste material. Suitable binders include, but are not limited to, natural and synthetic emulsion polymers and resins.

The thickeners may be present in the waste material in an amount of from 0.1-2.0 wt%, preferably 0.1-1.8 wt% and more preferably 0.1-1.5 wt% of the waste material. Typically, the thickener(s) constitute <1 wt% of the waste material. Suitable thickeners include, but are not limited to, cellulose, starch, polyvinyl alcohol, acrylic copolymer, and polyurethane. Polyurethane may be present as a polyurethane dispersion.

The biocides may be present in the waste material in an amount of from 0.1-2.0 wt%, preferably 0.1-1.8 wt% and more preferably 0.1-1.5 wt% of the waste material. Typically, the biocide(s) constitute <1 wt% of the waste material. Suitable biocides include, but are not limited to, natural and synthetic types formaldehyde donors, isothiazolinones, iodopropynyl butylcarbamate, and quaternary ammonium compounds.

The waste material may comprise any other components and materials used in the production of paints not referred to herein.

Typically, the most abundant component of the waste material is filler. The filler may comprise or consist of a carbonate, preferably calcium carbonate.

Step (a) of drying the waste material may comprise heating the waste material using a suitable heating means.

The waste material may be heated by any suitable industrial or commercial heating means. Preferably, the drying step is conducted in a heating drier, preferably a rotating drum drier, more preferably a conical rotating drum drier.

In practice, the drying step may operate as a continuous feed system.

The waste material may be heated to a temperature of from 250-750°C, preferably from 250-700°C, and most preferably from 250-650°C. Good results have been observed when heating the waste material at around 600°C.

In practice, the drying temperature should be below the decomposition temperature of one or more ingredients of the waste material. Preferably, the drying temperature is below the decomposition temperature of the filler. Preferably still, the drying temperature is below the decomposition temperature of a carbonate, particularly calcium carbonate. The drying temperature should be sufficiently high enough to effect drying of the waste material.

Following drying, the waste material may have an average moisture content of from 0-2%, preferably from 0-1.5% and most preferably from 0-1%. Preferably, the material has an average moisture content of <1%.

Step (b) of processing the waste material into a particulate form may comprise milling the waste material by grinding, crushing or cutting. Preferably, processing the waste material in step (b) comprises milling the waste material.

Milling the waste material may be conducted using any suitable milling apparatus known to a person skilled in the art.

After processing of step (b), the waste material will be in particulate form, wherein the particles have an average particle size of from 1-50 micron, preferably from 1-40 micron and most preferably from 1-30 micron. Preferably, the material has an average particle size of less than 50 microns.

The process of measuring average particle size would be apparent to a person skilled in the art. For example, a particle analyser such as the Malvern® Insitec® dry particle size analyser could be used. Such an analyser is designed to continuously measure and provide particle size distribution measurements from a pneumatically conveyed stream of powder based on the principle of laser scattering. Using a 200mm lens, the system can measure particle sizes within the range from 0.5-500 microns.

The process of measuring average moisture content would be apparent to a person skilled in the art. For example, a moisture analyser such as the Kern® Rapid MLB 50-3N Moisture Analyzer could be used. Such an analyser can measure moisture content by heating a sample with, for example, a halogen lamp, to a pre-set temperature. The moisture content is then calculated based on a loss of weight in the sample. The analyser can operate at a temperature range of from 50-160°C. In testing, samples of the present invention utilised a pre-set temperature of 105°C.

Steps (a) and (b) may be performed simultaneously. For example, steps (a) and (b) may be performed simultaneously within a processor. Such a processor may comprise both milling means and heating means.

The waste material may be simultaneously dried, milled and dispersed in a continuous closed-loop system. Such a system is explained in greater detail herein, but may comprise feeding waste material from a feed hopper into a processor. In the processor, the waste material may be simultaneously dried and milled, utilising a grinding rotor and heated air that is drawn through the processor by an exhaust fan. The resulting particulate product may be collected and conveyed for packaging or other further processing as desired.

The process of the present invention as described herein provides a recycled composition from a waste material.

The recycled composition may be odour free.

The recycled composition may undergo one or more subsequent steps as desired or as appropriate. For example, the recycled composition may undergo a quality control step. This may comprise analysing the composition to ensure it complies with manufacturing requirements and standards for its intended use, such as particle size and/or shape.

In certain instances, the recovered waste material may be obtained in a form that is unsuitable for efficient drying in the drying step. For example, the recovered waste material may be in an agglomerated form where the agglomerates are too large for efficient, optimum drying in the drying step of the present invention.

In some embodiments, therefore, the waste material may undergo a size reduction step prior to the drying step. The size reduction step may comprise breaking up the waste material into smaller agglomerates suitable for efficient drying in the process of the present invention. In some embodiments, the size reduction step is a de-agglomeration step.

Typically, the waste material obtained from the paint production process may be in the form of uniform and non-uniform agglomerates, having an average diameter of around 150mm. The initial size reduction step prior to the drying step may reduce the average agglomerate size of the waste material to around 5-10mm, preferably around 2-5mm.

The size reduction step may be conducted using apparatus that would be familiar to a person skilled in the art. In processing, good results have been obtained using a Kibbler Pre-Breaker.

The process for producing the recycled composition as described herein may further comprise the step of packaging the recycled composition.

The recycled composition can be stored for delivery. Preferably, the recycled composition is provided in bags, such as 1 tonne bags, for transport to manufacturers or the like. Preferably, the bags are reusable.

According to a further aspect of the present invention, there is provided a recycled composition obtainable by the process described herein.

According to a further aspect of the present invention, there is provided a recycled composition comprising a waste material from the paint production process having an average moisture content of from 0-1 % and an average particle size of <50 micron.

The recycled composition is desirable for use in industries that utilise fillers and/or utilise calcium carbonate, either as filler or otherwise.

For example, calcium carbonate is used as a filler in the production of paint, as described herein. The recycled composition of the present invention may be used to replace virgin filler in the production of paint. In some instances, it may be appropriate to use the recycled material as filler in paints of a non-white or darker colour, depending on the colour of the recycled material.

Thus, according to a further aspect of the present invention, there is provided a paint comprising the recycled composition as described herein.

According to a still further aspect, there is provided a use of a recycled composition as described herein as a component in paint. Typically, the component is a filler.

The process for producing the recycled composition as described herein may further comprise the step of incorporating the product of steps (a) and (b) into a paint. The recycled composition of the present invention may be used as a full or partial replacement for a filler used in paint production.

Similarly, calcium carbonate, fillers and the like are used in adhesives and also in construction chemicals, including chemicals used with cement, concrete or other construction materials. It is therefore envisaged that the recycled composition as described herein could be used to replace virgin calcium carbonate, fillers, etc. in adhesives and construction chemicals. Thus, according to a further aspect of the present invention, there is provided an adhesive and/or a construction chemical comprising the recycled composition as described herein. There is also provided a use of a recycled composition as described herein as a component in adhesive(s), construction chemical(s), concrete, cement, and the like.

The recycled composition is desirable for use in the carpet industry as a component in carpet production.

Thus, according to a further aspect of the present invention, there is provided a carpet comprising the recycled composition as described herein.

According to a still further aspect of the present invention, there is provided a use of a recycled composition as described herein as a component in a carpet.

Typically, a carpet comprises carpet fibres (or tufts), a primary backing layer, an adhesive and a secondary backing layer.

The adhesive and/or carpet backing in carpet may comprise a filler. A filler used in the adhesive and/or carpet backing can be calcium carbonate. Calcium carbonate is useful in the production of adhesives and sealants as it is relatively cheap and has desirable mechanical properties.

The process for producing the recycled composition as described herein may further comprise the step of incorporating the product of steps (a) and (b) into a carpet. The recycled composition of the present invention can be used as a full or partial replacement for the filler used in the adhesive and/or backing component of a carpet.

Thus, according to a further aspect of the present invention, there is provided a carpet adhesive and/or backing comprising a recycled composition as described herein.

According to a still further aspect of the present invention, there is provided a use of a recycled composition as described herein in a carpet adhesive and/or backing.

The recycled composition of the present invention is beneficial to the paint and carpet industries. For example, the paint industry significantly reduces its waste being sent to landfill and the carpet industry can provide carpet products having an increased percentage of recycled content. Moreover, the recycled composition can be utilised by the paint industry as a filler in the production of paint, which reduces the need to use virgin filler.

In order that the invention may be more clearly understood an embodiment thereof will now be described by way of example only, with reference to the accompanying drawings, of which:

Figure 1: illustrates a process diagram for the process of the present invention;

Figure 2: illustrates a schematic diagram showing the simultaneous drying and dispersal of the waste material in a closed-loop system;

Figure 3: illustrates a cross-section of a typical carpet comprising an adhesive component.

Referring to Figures 1 and 2, the process comprises an initial step (1a) of washing the apparatus used in the paint production process to provide a waste effluent. The waste effluent comprises the waste material. This step (la) may be performed by the paint manufacturer as part of the process of removing by-product from the apparatus.

Following this, the waste effluent is filtered (1 b) to remove water content and provide the waste material as a filter cake. The filter cake typically comprises a solids content of around 40-60% of the total mass.

The process of the present invention may comprise the initial steps (la) and (1b) although these steps are optional and may be performed by paint manufacturers.

The filter cake obtained in step (1b) can either be dried in step (2) or, if the filter cake is too bulky or agglomerated for efficient drying, it can be processed into smaller agglomerates in step (1). The processing of the filter cake in step (1) is optional and may break up the filter cake from agglomerates averaging 150mm diameter to agglomerates averaging 2-5mm in diameter.

In the drying step (2), the filter cake can be heated in a conical rotating drum drier. The waste material is dried in step (2) until it has a water content of around 0-2%. Once dried, the dry waste is milled in step (3) into a particulate form to produce the desired recycled composition. The average particle size of the recycled composition following processing is around 0.1-50microns.

Alternatively, and preferably, the drying step (2) and the milling step (3) are conducted simultaneously. A schematic diagram of the process is shown in Figure 2.

The apparatus used in the process essentially comprises a feed hopper (101), an air heater (102), an exhaust fan (103), a processing unit (104) and a product collector (105).

Waste material contained in the feed hopper (101) is fed into the processing unit (104).

In the processing unit (104), the filter cake is simultaneously heated and milled to a temperature of approximately 600°C. The processing unit (104) may be a Drymeister® supplied by Hosokawa Micron B.V.

In use, the feed hopper (101) is filled with waste material, which is fed into the processing unit (104). In the processing unit (104), the waste material is ground and dispersed into suitably fine particles by a grinding rotor. The air heater (102) provides a heated air stream that is drawn through the body of the processing unit (104) by the exhaust fan (103). The heated air causes moisture in the waste material to evaporate. The heated air also causes the waste material particles to be conveyed to the product collector (105), where they can then proceed for further processing (5).

The simultaneous drying / milling step (4) is conducted as a continual process, where yield can amount to around 5 tonnes of waste material per hour.

The waste material is processed in the simultaneous drying/milling step (4) until it has a water content of around 0-2% and average particle size of around 0.1-50 microns. It is possible in the system of Figure 2 to adjust the processing parameters to vary the moisture content and the particle size of the end product.

Once dried, the waste material is collected in the product collector (105) where the exhaust gases are removed and the resultant powder is ready for collection / packaging.

The recycled composition may then undergo additional processing steps (5) including storing, packaging, transportation. Finally, the product may be used as a replacement component for the filler used in carpet production or recycled for use as a filler component in paint. Typically, the recycled composition may be added to the adhesive (9) described below in place of some or all of the filler material, such as calcium carbonate.

Example 1:

Industry estimates show that greater than 90% of carpets produced today are of the tufted type shown in Figure 3.

Referring to Figure 3, a typical tufted carpet (6) comprises carpet fibres (7), a primary backing (8), an adhesive (9) and a secondary backing (10).

The adhesive (9) and/or backings (8) and (10) may typically contain a filler component (not shown). The filler component may be replaced in full or in part by the recycled composition of the present invention.

An example adhesive (9) used in carpet contains the following:

Table 1: Composition of typical adhesive compound for use in tufted carpet

The recycled composition of the present invention can be used to partially or fully replace the existing calcium carbonate filler used in the adhesive (9) of tufted carpet.

Typically, the composition of the present invention can replace around 20-100% of the calcium carbonate filler.

Thus, for example, the adhesive (9) incorporating the recycled composition of the present invention comprises the following composition:

Table 2: Composition of an adhesive comprising the composition of the present invention for use in producing tufted carpet

It has been shown in testing that the carpet comprising an adhesive made according to the composition of Table 2 has an improved tuft anchorage, improved delamination strength, and improved wear properties due to less yam shedding. It has also been shown to have improved handling due to an increased stiffness.

The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.

Claims

CLAIMS:

1. A process for the recycling of a waste material, the process comprising the steps of: a. drying a waste material recovered from a paint production process; and b. processing the waste material into a particulate form.

2. A process as claimed in claim 1, wherein the waste material comprises a by-product formed in the process of producing paint.

3. A process as claimed in claim 1 or claim 2, wherein the drying step (a) and the processing step (b) occur simultaneously.

4. A process as claimed in any preceding claim, wherein the waste material is recovered by washing apparatus used in the paint production process with water to provide a waste effluent.

5. A process as claimed in any claim 4, wherein the waste effluent is filtered to reduce or remove the water content to provide a residue comprising the waste material.

6. A process as claimed in any preceding claim, wherein the waste material has a solids content of around 10 to 90% w/w.

7. A process as claimed in claim 6, wherein the waste material has a solids content of around 40 to 60% w/w.

8. A process as claimed in any preceding claim, wherein the waste material comprises a filler material used in the paint production process.

9. A process as claimed in claim 8, wherein the filler is or contains a carbonate.

10. A process as claimed in claim 9, wherein the waste material is carbonate-based.

11. A process as claimed in claim 9 or claim 10, wherein the carbonate is calcium carbonate.

12. A process as claimed in any preceding claim, wherein the waste material further comprise additional components used in the production of paint, said addition components selected from the group consisting of water, pigments, additional fillers, binders, thickeners, and biocides.

13. A process as claimed in any preceding claim, wherein the step of drying the waste material comprises heating the waste material.

14. A process as claimed in claim 13, wherein the drying temperature is below the decomposition temperature of one or more ingredients of the waste material.

15. A process as claimed in claim 14, wherein the drying temperature is below the decomposition temperature of calcium carbonate.

16. A process as claimed in any preceding claim, wherein average moisture content of the waste material following step (a) is from 0-2%.

17. A process as claimed in any preceding claim, wherein the dried waste material is processed into particulate form by de-agglomeration and/or milling.

18. A process as claimed in any preceding claim, wherein the average particle size of the waste material following step (b) is less than SOmicrons.

19. A process as claimed in any preceding claim, wherein the waste material undergoes a size reduction step to break up the waste material prior to drying step (a).

20. A process as claimed in claim 19, wherein the size reduction step prior to the drying step reduces the average agglomerate size of the waste material to around 2-5mm.

21. A recycled composition obtainable by the process of any one of claims 1 to 20.

22. A carpet comprising the recycled composition of claim 21.

23. A paint comprising the recycled composition of claim 21.

24. Use of the recycled composition of claim 21 as a component in a carpet.

25. Use of the recycled composition of claim 21 as a component in paint.

26. A carpet adhesive and/or carpet-backing comprising the recycled composition of claim 21.

27. Use of the recycled composition of claim 21 in a carpet adhesive and/or carpetbacking.