Distillation of plastic waste to form waterproofing products

Abstract

A method of distilling petrochemical-derived plastic (PDP) waste comprising: a) heating the PDP waste to form a vapour; and b) collecting and cooling the vapour to obtain a distillate, wherein the distillate is collected as a first fraction and a second fraction; liquid and semi-solid waterproofing products and compositions; use of same to increase the water resistance of a substrate.

Description

[0001] Distillation of plastic waste to form waterproofing products

[0002] Introduction

[0003] The invention relates to methods of distilling petrochemical-derived plastic (PDP) waste and products obtained thereby having waterproofing or waterproofing and lubricating properties. The invention also relates to compositions comprising one or more of the products of the invention.

[0004] The products and compositions may be used to provide waterproofing coatings or incorporated into products to increase their water resistance.

[0005] Background

[0006] Over recent years, problems relating to the accumulation of petrochemical-derived plastic (PDP) waste and provision for its safe disposal has become more widely appreciated. In the UK, for example, landfill capacity is limited, and recycling provision is insufficient to handle all locally generated plastic waste. Export of plastic waste for processing overseas is not a sustainable solution and can lead to unintentional release of waste plastic into the environment. The harmful effects of accumulated plastic waste in the environment, including in the oceans, is becoming more widely appreciated.

[0007] Recycling of PDP is known, for example closed loop recycling to make new items of the same type, e.g. plastic drinks bottles are recycled to make further plastic drinks bottles, and open loop recycling in which products are used to make further products of lower quality. Both processes have limitations due to contaminant build-up and cumulative polymer degradation. Both closed loop and open loop recycling also perpetuate the use of plastics materials and generation of further PDP waste, and thus have a limited impact on reducing plastic pollution.

[0008] Some plastics are amenable to depolymerisation, which can be used to regenerate the starting monomers or to produce fuels. However, such processes can be energy intensive and may yield an inferior product because of potential contamination of the input materials. Pyrolysis of PDP waste is also known. This process can also be used to regenerate the monomers that gave rise to the PDP, but again the process is not a clean or economically attractive source of monomers. Pyrolysis can also be used to generate synthetic fuel oil, but the process is not energy efficient and can result in the generation of potentially harmful by-products.

[0009] For example, JP 2000-169856 A describes the use of recycled PDP waste to produce synthetic asphalt. The process involves mixing waste plastics and heavy oil, thermally decomposing the product in a pyrolysis reaction at temperatures of about 300-450°C and removing low-boiling components and gas components from the resultant composition. The low-boiling components and off gases may be condensed as part of a detoxifying process for the by-products of the process, but the primary product is not distilled.

[0010] CN 1318284 A describes application of a product derived from polyethylene, polypropylene or polystyrene waste to desert land to promote plant growth. The product is obtained by cracking PDP waste plastic in a pyrolysis reactor at a temperature of about 320-420°C to produce a mixture of solid hydrocarbons and combining it with organic solvents, surfactants and water.

[0011] PL 212463 B1 describes methods for obtaining liquid fuel components from PDP waste. The method involves melting the plastic waste, sedimentation and removal of particulates, two heating steps first with a specific montmorillonite and quartz sand catalyst at about 300-400°C and then with a type A zeolite catalyst in acid form at about 260-300°C, then condensation of the product. Hence, PL 212463 B1 describes a complex process involving multiple heating steps, each with different, specialised catalyst.

[0012] CN 1506396 A describes a process involving heating PCP waste to 600-1000°C followed by condensation to provide a colloid. The use of such high temperatures requires significant energy usage and consequent expense.

[0013] CN 1626589 A and CN 101418195 A describe processes for making waterproof paints and adhesives from polystyrene waste. At the same time, industry is increasingly aware of the need to work sustainably and reduce the use of virgin materials. In many cases, this growing awareness is accompanied by legislation to reduce environmental harms and promote more sustainable technologies. The building industry, in particular, recognises the need for recycled products to replace current products. One area where a recycled product is not currently available is the waterproofing of recoating of roofs, particularly flat roofs.

[0014] Accordingly, there is a need for solutions to the growing problem of plastic waste. There is also a need to provide cost effective, sustainable and recycled products that match or exceed the quality of existing products. - recycled - need recycles waterproofing / recoating system for roofs, e.g. flat roofs.

[0015] Accordingly, an object of the invention is to provide a method of recycling PDP waste to provide useful, sustainable recycled products. Preferably, the method is simple and cost effective. Another object of the invention is to provide sustainable recycled waterproofing applications. A further object of the invention is to provide sustainable recycled products and compositions for waterproofing building materials, for example roofs.

[0016] Summary of the Invention

[0017] Accordingly, in one aspect the invention concerns a method of distilling petrochemical- derived plastic (PDP) waste comprising: a) heating the PDP waste to form a vapour; and b) collecting and cooling the vapour to obtain a distillate, wherein the distillate is collected as a first fraction and a second fraction.

[0018] The PDP waste input can contain sorted plastics materials or mixed streams. Typically PDP waste comprises one or more of polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), polycarbonate and acrylonitrile butadiene styrene (ABS). A significant component of PDP waste includes plastic packaging, which typically comprises about 60% PE and about 11 % PP by weight. Accordingly, the PDP waste may comprise polyethylene (PE) and / or polypropylene (PP) and has a melting point of approximately 120-220°C. The PDP waste may also comprise PE and PP having a melting point of approximately 120- 180°C.

[0019] Accordingly, in a preferred embodiment, the invention provides a method of distilling petrochemical-derived plastic (PDP) waste comprising: a) heating the PDP waste to form a vapour; and b) collecting and cooling the vapour to obtain a distillate, wherein the distillate is collected as a first fraction and a second fraction, and wherein the PDP waste comprises polyethylene (PE) and / or polypropylene (PP) and has a melting point of approximately 120-220°C.

[0020] In preferred embodiments, the PDP waste comprises low density polyethylene (LDPE) and / or high density polyethylene (HDPE). More preferably, the PDP waste comprises LDPE. The LDPE and / or HDPE may be provided in the form of packaging waste, such as food packaging waste.

[0021] In preferred embodiments, the PDP waste comprises at least 70% by weight PE and / or PP, for example, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 97%, at least 98% or at least 99% by weight PE and / or PP.

[0022] In other preferred embodiments, the PDP waste does not comprise polystyrene.

[0023] Optionally, the PDP waste is physically processed, for example by cutting or milling, prior to step a) to provide a more homogenous input.

[0024] Step a) of the method comprises heating the PDP waste to a temperature of at least 300°C. Preferably, step a) comprises heating the PDP waste to a temperature not exceeding 400°C, 390°C, 380°C, 370°C, 360°C, or most preferably 350°C. Without wishing to be bound by any theory, it is believed that at temperatures of at least 300°C, for example 300-350°C, 300-340°C, 300-330°C, 300-320°C or 300-310°C, the PDP waste is “cracked”, resulting in large polymer molecules forming smaller more volatile molecules. These molecules evaporate to form a vapour that is condensed and collected as a distillate, which is collected as a first fraction and a second fraction.

[0025] The use of temperatures of, for example, 300-350°C ensures that the method of the invention is energy efficient and cost effective, for example in comparison to known methods using heating temperatures of more than 400°C, more than 600°C or even 1000°C. Without wishing to be bound by any theory, the use of lower temperatures, for example in comparison to known pyrolysis methods, is believed to reduce or eliminate chemical degradation of the products, for example as a result of oxidation or rearrangement of the polymers present in the initial PDP waste.

[0026] In addition, the method of the invention is relatively simple, when compared to known methods of recycling plastic waste. For example, in preferred embodiments step a) consists of a single heating step. Thus, there is no need for the PDP waste to be heated to different temperatures in separate steps or moved between multiple heating vessels. In the same way, in preferred embodiments, the heating step a) is carried out in the absence of a solvent and / or a catalyst. Again, this simplifies the method, which is preferably based on dry distillation of the PDP waste using a single heating step without a catalyst.

[0027] The distillation method can be carried out using conventional distillation apparatus, at a laboratory, test rig (pilot) or commercial scale. Typically the PDP waste will be placed in a vessel, which may be a steel fermenter pot, provided with a door or other access point for adding the PDP waste and an outlet for the vapour. When heat is applied, the vapour passes to a condenser provided with a water inlet and outlet separated from the vapour to provide cooling and an outlet through which the condensed vapour can be collected. Suitable distillation apparatus is well-known in the art and available to the skilled person.

[0028] Optionally, the method may comprise the further step: c) deodouring and decolouring the first fraction and / or the second fraction by passing each fraction through one or more of sodium bicarbonate, diatomaceous earth and charcoal. In test distillations, there was minimal degradation of the product, and hence minimal odour or discolouration. However, if undesirable odours or colours are present in the first fraction or second fraction, these can be removed by passing either fraction through a bed of sodium bicarbonate, diatomaceous earth (Celite®), charcoal, or successively passing either fraction through sodium carbonate and diatomaceous earth, sodium carbonate and charcoal, diatomaceous earth and charcoal, or sodium carbonate, diatomaceous earth and charcoal in any order. The fractions may be passed through the beds of deodouring and decolouring materials under gravity or under vacuum.

[0029] When the method of the first aspect was carried out, the first fraction is a liquid at ambient temperature (approximately 20°C). Similarly, the second fraction presents as a semi-solid wax, gel or paste at ambient temperature. In pilot-scale applications of the method using LDPE waste, the first fraction comprised approximately 20% of the total output and the second fraction composed about 80% of the total output by weight.

[0030] A second aspect of the invention provides a liquid product obtainable by the method of the first aspect. The liquid product is obtained as the first fraction of the distillation method and, typically, the liquid dries to form a water repellent coating.

[0031] A third aspect of the invention provides a semi-solid product obtainable by the method of the first aspect. The semi-solid product is formed as the second fraction of the distillation method and, typically, the semi-solid product has water repellent and lubricating properties.

[0032] The liquid product of the second aspect, or the semi-solid product of the third aspect may also be resistant to UV light and / or fire-resistant. The liquid product of the second aspect, or the semi-solid product of the third aspect may also or additionally be resistant to oxidation and corrosion, for example as a result of exposure to or contact with acids. The liquid product of the second aspect, or the semi-solid product of the third aspect may also or additionally be resistant to weathering, for example as a result of exposure to strong winds or harsh environments. Resistance to UV light may be determined by applying the product to a test substrate, exposing it to UV light of a defined wavelength (e.g. 256 nm) for a test period (e.g. 4 days) and assessing the sample after the test period. Fire resistance may be assessed by exposing the product, typically applied to a test substrate, to a naked flame for a test period (e.g. 2 minutes) and observing and assessing the sample after the test period, for example noting whether the sample ignited or was visibly damaged after exposure to the flame. Resistance to oxidation or corrosion damage may be determined by applying the product to a test substrate, exposing it to a strong acid for a test period (e.g. 4 days) and assessing the sample after the test period. Resistance to weathering may be determined by applying the product to a test substrate, subjecting the sample to sand abrasion for a test period (e.g. 4 days) and assessing the sample after the test period. For all tests, a control substrate to which the product has not been applied may be subjected to the same test conditions and compared with the test sample, for example to determine the level of UV protection afforded to a substrate coated with the product. Similar comparative assessment for fire damage, acid-induced corrosion or sand abrasion may be carried out, as appropriate to the properties being tested.

[0033] A further aspect of the invention provides a liquid waterproofing product, i.e. a recycled liquid waterproofing product, comprising a mixture of hydrocarbons having a chain length of at least C10. The liquid product may be obtained as the first fraction of the distillation method of the first aspect, may be derived from PDP waste comprising PE and / or PP, and typically comprises a mixture of higher alkanes and / or alkenes. The hydrocarbons typically include alkanes and or alkenes having a chain length of C10 to C30, including chain lengths of C10, C11 , C12, C13, C14, C15, Ci e, C17, Cis, C19, C20, C21 , C22, C23, C24, C25, C26, C27, C28, C29 and C30. Headspace gas chromatography - mass spectrometry (GC-MS) of a sample of the liquid waterproofing product obtained from distillation of LDPE waste indicated that a significant component of the mixture was undecane. For example, the product may comprise at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45% or at least 50% by weight of undecane.

[0034] Additional Fourier-transform infrared spectroscopy (FTIR) analysis indicated that the liquid also comprises a polymeric component identifiable as ethylene propylene diene terpolymer. Other polymeric components will be present in products obtained from PDP waste comprising plastics other than LDPE.

[0035] Preferably the liquid waterproofing product dries to form a waterproof coating. Thus the liquid product may be applied to a substrate and allowed to dry by evaporation to form a waterproof coating.

[0036] A further aspect of the invention provides a semi-solid waterproofing and lubricating product comprising a mixture of hydrocarbons having a chain length of at least C10. The semi-solid product may be obtained as the second fraction of the distillation method of the first aspect, may be derived from PDP waste comprising PE and / or PP, and typically comprises a mixture of higher alkanes and / or alkenes. The hydrocarbons typically include alkanes and or alkenes having a chain length of C10 to C30, including chain lengths of C10, C11, C12, C13, C14, C15, Cie, C17, Cis, C19, C20, C21 , C22, C23, C24, C25, C26, C27, C28, C29 and C30. Headspace gas chromatography - mass spectrometry (GC-MS) of a sample of the semi-solid waterproofing product obtained from distillation of LDPE waste indicated that a primary component of the mixture was undecane. For example, the product may comprise at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45% or at least 50% by weight of undecane.

[0037] Additional Fourier-transform infrared spectroscopy (FTIR) analysis indicated that the liquid also comprises a polymeric component identifiable as ethylene propylene diene terpolymer. Other polymeric components will be present in products obtained from PDP waste comprising plastics other than LDPE.

[0038] The semi-solid waterproofing and lubricating product typically appears as a wax or gel. It is believed that the semi-solid product has a higher proportion of longer chain (higher molecular weight) compounds than the liquid product, and hence has a higher melting point. For example, the semi-solid product may have a higher proportion of dodecane, hexadecane and / or tridecane than the liquid product. Typically, the semi-solid waterproofing product does not dry when applied to smooth, non-porous surfaces. This allows the product to function as a lubricant, e.g. when applied to glass, metal or plastic substrates. Under test conditions, the semi-solid product maintains its lubricating properties under high temperature, low temperature (freezing) and high friction conditions.

[0039] A further aspect of the invention provides a composition comprising (a) the liquid product of the invention, (b) the semi-solid product of the invention, or a mixture of (a) and (b). Mixing (a) and (b) allows the consistency and viscosity of the composition to be varied to suit different uses and applications. For example adding 5%, 10% or 20% by weight of (b) to liquid (a) provides a thicker liquid composition.

[0040] The composition may further comprise one or more additional components to support additional uses based on modified properties of the composition. In some embodiments, the composition further comprises one or more of carbon black, foam glass dust, silica, chalk and fine broken glass. In other applications, the composition may comprise rubber particles or shards, which can be obtained from comminuted used tyres. In embodiments where such solid components are added, the solid component may comprise 0-25% or 25-50% of the composition. In embodiments where solid materials are combined with the primary product to increase fire retardant properties, a 25-50% w / v suspension is typically used.

[0041] The composition may further comprise a pigment or a curing agent, or both. The presence of a pigment can assist the user in confirming full coverage when applying the composition to a surface or may be desirable in its own right, for example if the composition is formulated with other components to form a paint. The curing agent can assist drying of the product, for example to reduce the time between application of multiple coats of the composition. Suitable pigments and curing agents are well- known in the art.

[0042] A further aspect of the invention provides use of the composition of the invention to increase the water resistance of a substrate selected from stone, bricks, building blocks, roofing tiles, flat roofs, cement, metal, glass, wood, painted or rendered walls, tarmac, or plastic substrates. The composition may be applied to the surface of the substrate, for example to form a waterproof coating. Alternatively, the composition may be incorporated into a paint, render, grout, cement or tarmac product.

[0043] Detailed Description of the Invention

[0044] Product characteristics

[0045] The composition of the primary liquid product and the secondary wax or gel product depends on the PDP waste input to the distillation process. When PE packaging waste has been used as an input, analysis of the primary and secondary products has shown that the primary and secondary products comprise the same or similar mixtures of compounds. However, the secondary product contains an increased proportion of higher molecular weight compounds, consistent with its presentation as a wax or gel, rather than a liquid at ambient temperature.

[0046] Headspace gas chromatography - mass spectrometry (GC-MS) of samples of the primary and secondary products has shown that both products comprise a mixture of hydrocarbons having a chain length of at least C10, including both higher alkanes and the corresponding higher alkenes including molecules having a chain length of C10 to C30, including chain lengths of C10, C11, C12, C13, C14, C15, Cie, C17, Cis, C19, C20, C21 , C22, C23, C24, C25, C26, C27, C28, C29 and C30. Headspace gas chromatography - mass spectrometry (GC-MS) of a sample of the liquid waterproofing product indicated that a significant component of the mixture was undecane.

[0047] Additional molecules detected in the GC-MS analysis of the primary product included decane, dodecane, tridecane, 4,7-dimethyl-undecane, 4,6-dimethyl-dodecane, 2,7, 10-trimethyl-docecane, 2,6, 11 -trimethyl-dodecane, hexadecane, 2,5,6-trimethyl- decane, 4,6-dimethyl-undecane, tetradecane, 3.5-dimethyl-octane, and 5-methyl- decane, 2-methyl-decane. Also detected were 1 -heptyl-2-methyl-cyclopentane, 3- undecene, octyl-cyclopropane, 1 -docecene, 2-undecene, 1 -undecene, 1 -decene, 1 - hecyl-2-propyl-cyclopropane, E-11 , 13-tetradecadien-1 -ol, 3-tetradecene, 1 -ethyl-2- heptyl-cyclopropane, 1 -tridecene, 3-tridecene, 1 -undecanol, 1 -butyl-2-pentyl- cylclopropane, nonyl-cyclopropane, 3-dodecene, 3-undecene, 2-tridecene, 2- docecene, 1 -pentyl-2-propyl-cyclopropane, 5-undecene, 2,6-dimethyldecane, pentadecane, 2,3,7-trimethyl-octane, 2,6-dimethyl-undecane, 2,4,6-trimethyl-octane ad 2,7-dimethyl-undecane.

[0048] A similar range of molecules were detected in the GC-MS analysis of the secondary product.

[0049] Additional Fourier-transform infrared spectroscopy (FTIR) analysis indicated that the primary liquid product and the secondary wax or gel product also comprises a polymeric component identifiable as ethylene propylene diene terpolymer. Without wishing to be bound by any theory, the FTIR analysis is believed to identify less volatile components of the products, whereas the GC-MS analysis identifies more volatile, lower molecular weight compounds.

[0050] Additional time-of-flight mass spectrometry analysis also indicated that both the primary and secondary products were mixtures of many components, with molecular weights ranging from about 185 to several thousand. The liquid primary product contained a greater proportion of lower molecular weight species than the secondary product.

[0051] Both the primary and secondary products have been shown to have waterproofing properties. When applied to various substrates, both products reduce the wettability of the substrate, as measured by the contact angle observed when a sessile drop of pure water is applied to the surface. The wettability of a number of materials is shown in Table 1 below.

[0052] Table 1

[0053] In initial tests, applying the primary product to concrete resulted in observed contact angles between 97° and 110°. Application to cardboard resulted in observed contact angles between 105° and 108°, increasing to 113° after application of a second coat of the primary product. In contrast, untreated cardboard resulted in observed contact angles between 45° and 60°. Application to wood (pine) resulted in an observed contact angle of 110°, compared to 45-69° for untreated pine.

[0054] Both the primary and secondary products have also been shown to be mechanically tough, resistant to UV degradation. The fire retardant properties of the primary and secondary products have also been assessed (when used alone and when combined with other materials). Compositions comprising the primary and / or secondary product

[0055] The primary liquid product, the secondary semi-solid product or mixtures of both products may be incorporated into compositions, optionally comprising additional components. Mixing the primary and secondary products allows the consistency and viscosity of the composition to be varied to suit different uses and applications. For example mixtures of the primary and secondary products comprising 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 70%, 75%, 80%, 85%, 90% or 95% of the secondary product can be prepared. Increasing the proportion of the secondary product increases the viscosity of the mixture and increases the drying time, thus providing for a range of products having different physical properties but retaining the waterproofing properties of both products.

[0056] The composition may further comprise one or more additional components to support additional uses based on modified properties of the composition. The additional components may support the use of the primary product for waterproofing and the secondary product for waterproofing and / or lubrication, may modify the characteristics of the products for example to enhance fire retarding properties, or may use the primary and / or secondary product as a minor component to add waterproofing or water resistant properties to existing products.

[0057] Suitable additional components include:

[0058] • paint or other coating materials for use on wood;

[0059] • pigments to assist in ensuring complete coverage of surfaces;

[0060] • curing agents to promote drying and / or reduce the interval between applying successive coats of the composition;

[0061] • grout, cement, external render and similar products;

[0062] • tarmac

[0063] • carbon black, foam glass dust, silica, chalk and / or fine broken glass for fire- resistant coatings

[0064] Accordingly, compositions comprising the primary and / or secondary product have broad application. Uses of the products and compositions

[0065] The products and compositions of the invention can be applied directly to substrates or incorporated into products such as paint, render, grout, cement or tarmac to introduce waterproofing or water resistant properties. Although waterproofing or water resistant properties are a primary consideration, the properties of the products and compositions may in some applications provide additional benefits, e.g. in terms of improved fire resistance, durability, oxidation and corrosion resistance, resistance to weathering and wind damage, and / or UV resistance.

[0066] The primary product can be used for multiple waterproofing applications, in which the product or a composition comprising the product is applied using any suitable technique, for example painting or spraying. Exemplary uses are described below:

[0067] Compositions can be used to waterproof wood or timber products, both internal and external. Compositions comprising paint, wood stain, varnish or other coating materials in addition to the primary product can be used to provide more durable waterproof products. Alternatively compositions comprising the primary product alone or compositions lacking other coating materials can be applied before or after conventional paint or coating materials to increase waterproofing and longevity of the coating.

[0068] Compositions can be used to waterproof cardboard products. For example, compositions can be used to increase the weather-resistance and resilience of packaging materials. Potential applications in food packaging are also envisaged, both for containing liquid products and for protecting dry products from water damage.

[0069] Compositions can be used for waterproofing natural and composite stone products, concrete and cement products, and other building materials such as bricks, building blocks, roofing tiles, and flat roofs. Where a thicker product consistency is desirable, compositions comprising a proportion of the secondary product can be used. Pigments bay be added to such compositions to assist the user in ensuring complete coverage of the materials, or the exposed parts of the materials. One or more curing agents may also be incorporated into the compositions to promote drying and reduce the time interval between applications of one or more subsequent coats. Compositions can be used in combination with pigments, curing agents and other core components to provide a waterproof roofing system. This can be applied, for example, to flat roofs. Such compositions have been shown to mix well with current liquid applied roofing products, confirming the compatibility of the compositions with existing materials and the suitability of the compositions to replace current non-recycled polymer components used in liquid applied roofing products.

[0070] Compositions can be used to waterproof electronic circuit boards and other electrical equipment. For such applications, the compositions comprise a curing agent to promote drying of the composition on smooth plastics and metal substrates. For such applications, the compositions are typically applied by spraying one or more coats of the composition onto the electronic circuit board or equipment.

[0071] Compositions can be used to increase the water resistance of fabrics, for example clothing, footwear and tenting. Typically compositions for such uses would include a curing agent to ensure optimal drying and a treated fabric having an acceptable finish.

[0072] Compositions optionally comprising solid components such as carbon black, glass foam dust, silica, chalk and fine broken glass, and optionally additionally comprising a curing agent can be used as a fire retardant for thatch roofing.

[0073] Compositions, optionally comprising a curing agent and optionally further comprising a powder catalyst can be used to treat metal surfaces, including painted and powder metal surfaces, to provide water resistance and / or to increase the durability of conventional coatings. Such compositions can be used for land-based and maritime applications and are expected to increase the interval between regular maintenance and re-application of protective coatings.

[0074] Compositions can be used to aid the dispersion of water from glass surfaces. For example a liquid composition, optionally comprising a curing agent, can be applied to a glass surface. When the composition has dried, the treated glass exhibits reduced wettability and water falling on the glass disperses almost instantly. Such treatment of glass may be particularly useful for treating windows in buildings or in vehicles where maintenance of visibility is required.

[0075] Compositions can be included as a component of paints, particularly paints for external use, grouts, cement, render, or tarmac to improve the properties of such materials, for example by increasing their water resistant or waterproofing properties. When included in external materials or coatings for buildings, the compositions can provide a waterproof yet breathable layer protecting the surface. When included as a component of tarmac, the compositions can reduce the incidence of standing water. This may contribute to improved road safety in wet conditions.

[0076] Exemplary uses the semi-solid secondary product and compositions comprising the secondary product, optionally mixed with a proportion of the primary product to adjust its thickness and consistency, are described below. Generally, the secondary product can be used for the same waterproofing applications as the primary product.

[0077] Compositions comprising the secondary product can be used in the same way as compositions comprising the primary product for waterproofing building materials such as bricks, building blocks, roofing tiles and flat roofs, and to stone, concrete and cement, as described above. As for compositions comprising the primary product, pigments, curing agents and other additional components are optionally present.

[0078] Compositions comprising the secondary product can be used in combination with pigments, curing agents and other come components to provide a waterproof roofing system in the same way as compositions comprising the primary product. This can be applied, for example, to flat roofs.

[0079] Compositions comprising the secondary product can be used to waterproof dry lining products or piasterwork in areas likely to be exposed to water before additional cladding or tiling is installed. This provides a second layer of protection if the cladding or tiling is compromised, thus protecting the underlying structures in wet areas of a building. Compositions comprising the secondary product have demonstrated advantageous properties when used as a grease or lubricant on metals and other smooth surfaces. Lubricant properties were retained in both hot and cold climates. In high heat, the compositions remain in place and continue to function as lubricants but exhibit reduced viscosity. In freezing conditions, the lubricating compositions did not seize, but retained lubricating function even after several months of exposure to cold.

[0080] The invention is now illustrated by way of the following examples, with reference to the accompanying drawings, in which:

[0081] Fig. 1 shows Headspace GC-MS analysis of the primary liquid product - a) shows the column temperature profile and b) shows the results in the form of a chromatogram and mass spectrum;

[0082] Fig. 2 shows FTIR analysis of the primary liquid product;

[0083] Fig. 3 shows Headspace GC-MS analysis of the secondary semi-solid wax product in the form of a chromatogram and mass spectrum, and

[0084] Fig. 4 shows FTIR analysis of the secondary semi-solid wax product.

[0085] Example 1 - Distillation of LDPE waste

[0086] LDPE waste in the form of used plastic packaging was collected, washed and physically cut into small pieces prior to distillation in a stainless steel pilot scale distillation unit having a 30cm internal diameter.

[0087] The distillation unit was heated to an internal temperature 300°C and the vapour from the LDPE waste was collected, cooled in a condenser unit mounted above the distillation unit, and the condensed product was collected as two fractions.

[0088] The first fraction made up approximately 20% of the product and was a liquid at ambient temperature. The second fraction made up approximately 80% of the product and was a semi-solid wax or gel at ambient temperature. Both products were lightly coloured, both appearing as a pale yellowish brown. Filtration of samples of the primary product through a bed of sodium bicarbonate, Celite® (diatomaceous earth) or charcoal resulted in a reduction in colour and odour. There was no evidence of significant chemical degradation of either the primary or secondary product.

[0089] Example 2 - Analysis of the primary liquid product

[0090] The primary product was subjected to GC-MS, FTIR and time-of-flight (TOF) mass spectrometry analysis.

[0091] Two samples were provided for Headspace GC-MS analysis, one as a viscous liquid, the other as a waxy semi-solid product. All samples were prepared in a sealed vial for volatilisation, the liquid at a volume of 20ul, the waxy solid at a weight of 20 mg. Analysis of the waxy solid sample is described in Example 3.

[0092] Headspace GC-MS was performed on a Scion 456 GC equipped with a TQ mass analyser and a HS headspace autosampler. The headspace volatilisation was performed by holding the sample at 100°C for 20 minutes. The samples were run using a column temperature profile starting at 60°C and holding for 1 minute then ramping to 240°C at 13.5 minutes, with an isothermal section at the end of the run for 3 minutes. This temperature profile is shown in Fig. 1 a.

[0093] The liquid sample displayed a main series of peaks separated by around 0.8 minutes of retention time. Investigating the mass spectra of these peaks, it was observed that they correspond to an alkane series with fragments separated by 14 m / z, assigned as the mass of a CH2 group. In Fig. 1 b) an example spectrum is shown for the peak at 3.544 minutes.

[0094] A library search confirmed that this spectrum corresponds to undecane.

[0095] The other peaks which are close to the 3.544 minute peak, assigned as the similar species in the library search. These appeared mainly as forms with ring structures or as the alkene form of the alkane from the series.

[0096] The rest of the peaks assigned to other alkane and alkene species, with smaller species appearing earlier in the chromatogram, larger species appearing later in the chromatogram. Compounds identified in the sample included decane, dodecane, tridecane, 4,7- dimethyl-undecane, 4,6-dimethyl-dodecane, 2,7,10-trimethyl-docecane, 2,6,11- trimethyl-dodecane, hexadecane, 2,5,6-trimethyl-decane, 4,6-dimethyl-undecane, tetradecane, 3.5-dimethyl-octane, and 5-methyl-decane, 2-methyl-decane. Also detected were 1 -heptyl-2-methyl-cyclopentane, 3-undecene, octyl-cyclopropane, 1 - docecene, 2-undecene, 1 -undecene, 1 -decene, 1 -hecyl-2-propyl-cyclopropane, E- 11 ,13-tetradecadien-1 -ol, 3-tetradecene, 1 -ethyl-2-heptyl-cyclopropane, 1 -tridecene, 3-tridecene, 1 -undecanol, 1-butyl-2-pentyl-cylclopropane, nonyl-cyclopropane, 3- dodecene, 3-undecene, 2-tridecene, 2-docecene, 1-pentyl-2-propyl-cyclopropane, 5- undecene, 2,6-dimethyldecane, pentadecane, 2,3,7-trimethyl-octane, 2,6-dimethyl- undecane, 2,4,6-trimethyl-octane ad 2,7-dimethyl-undecane.

[0097] The results of Headspace GC-MS analysis showed a series of repeated peaks which, upon in investigation of the corresponding mass spectra, were shown to be alkane and alkene series increasing in chain length as the retention time increases. The chromatogram for the wax sample showed a bias towards the higher molecular weight species, suggesting a lesser presence of the smaller volatile compounds.

[0098] Additional FTIR analysis of a sample of the primary liquid product was also carried out. The FTIR results are shown in Fig. 2. The results indicated that the liquid product also comprises a polymeric component identifiable as ethylene propylene diene terpolymer.

[0099] Additional mass spectrometry using electrospray - TOF analysis was also carried out on of a sample of the liquid product was also carried out. The TOF analysis indicated that that the primary product was a mixture of many components, with molecular weights ranging from about 185 to several thousand. The liquid primary product was found to contain a greater proportion of lower molecular weight species than the secondary product.

[0100] Example 3 - Analysis of the secondary semi-solid wax product

[0101] The secondary product was subjected to GC-MS, FTIR and time-of-flight (TOF) mass spectrometry analysis under the same conditions described in Example 2. The GC-MS results are shown in Fig. 3. The semi-solid wax chromatogram consisted of the same sequence of peaks as the liquid sample, however the bias was shifted toward the larger alkane / alkene species compared to that of the liquid sample of Example 2.

[0102] A library search confirmed that these species are the same as those in the liquid sample of Example 2.

[0103] The results of Headspace GC-MS analysis showed a series of repeated peaks which, upon in investigation of the corresponding mass spectra, were shown to be alkane and alkene series increasing in chain length as the retention time increases. The chromatogram for the wax sample showed a bias towards the higher molecular weight species, suggesting a lesser presence of the smaller volatile compounds.

[0104] Additional FTIR analysis of a sample of the secondary semi-solid product was also carried out. The FTIR results are shown in Fig. 4. The results indicated that the semisolid product also comprises a polymeric component identifiable as ethylene propylene diene terpolymer.

[0105] Additional mass spectrometry using electrospray - TOF analysis was also carried out on of a sample of the secondary semi-solid product was also carried out. The TOF analysis indicated that that the secondary product was a mixture of many components, with molecular weights ranging from about 185 to several thousand. The liquid primary product was found to contain a greater proportion of lower molecular weight species than the secondary product.

[0106] Example 4 - Testing of product properties

[0107] Both the primary and secondary products were tested to assess their waterproofing properties.

[0108] Wettability is a measure of the ability of a liquid to maintain contact with a solid surface as a result of intermolecular interactions when the liquid and solid surface are brought together. Wettability is an indication of the degree of wetting as a result of a balance between cohesive forces and adhesive forces.

[0109] Wettability is typically expressed in terms of a contact angle (9) between a liquid droplet and a solid surface. A contact angle of 0° indicates perfect wetting; contact angles between 0° and 90° indicate high wettability; contact angles between 90° and 180° indicate low wettability; and a contact angle of 180° indicates no wetting of the surface.

[0110] For non-ideal surfaces, i.e. surfaces that are not idealised mathematical models, the Wenzel model may be used in simple circumstances to determine the contact angle using the formula: cos (6‘) = r cos (6) where 6* is the apparent contact angle which corresponds to the stable equilibrium state (i.e. minimum free energy state for the system), t is the roughness ratio, a measure of how surface roughness affects a homogeneous surface. The roughness ratio is defined as the ratio of true area of the solid surface to the apparent area.

[0111] For heterogeneous surfaces, the Wenzel model is not sufficient and the Cassie-Baxter model is used. The contact angle is determined using the formula: cos (6*) = rf cos (6y) + f - 1 where the n is the roughness ratio of the wet surface area and f is the contact fraction of solid surface area wet by the liquid. If f = 1 and n = r, the Cassie-Baxter equations becomes the Wenzel equation.

[0112] When applied to various substrates, both the primary and secondary products were observed reduce the wettability of the substrate, as measured by the contact angle observed when a sessile drop of pure water was applied to the surface. In initial tests, applying the primary product to concrete resulted in observed contact angles between 97° and 110°. Application to cardboard resulted in observed contact angles between 105° and 108°, increasing to 113° after application of a second coat of the primary product. In contrast, untreated cardboard resulted in observed contact angles between 45° and 60°. Application to wood (pine) resulted in an observed contact angle of 110°, compared to 45-69° for untreated pine.

[0113] Both the primary and secondary products were also tested for mechanical strength and resistance to UV radiation (data not shown). The products were observed to be mechanically tough and resistant to UV degradation.

[0114] Example 5 - Fire resistance testing of compositions

[0115] Samples of the primary liquid product and secondary semi-solid product were mixed with 25-50% w / v particulate solids, poured onto a card substrate and allowed to dry for 1 -2 days. The solids tested were carbon black, foam glass dust, silica (SiCh) “flour”, chalk (CaCOs) and fine broken glass.

[0116] The physical properties of the resultant samples were assessed by probing the samples with a pointer. The resilience and robustness of the samples is noted in the following table.

[0117] The samples were then exposed to a naked flame for 2 minutes to assess their flame retardant properties.

[0118] All five liquid samples were essentially unchanged after exposure to the naked flame. This the primary product, when mixed with any of carbon black, foam glass, silica, chalk or fine broken glass was non-flammable and protected the card substrate.

[0119] The samples based on the secondary product showed a lesser and variable degree of fire resistance. The carbon black sample did not protect the card substrate, and a section ignited after exposure to a naked flame for 2 minutes. The foam glass, silica and chalk samples showed limited fire resistance, with each exhibiting some areas of charring. Similar results were also observed for the fine broken glass sample, although the area of charring was perhaps more extensive.

[0120] Thus, the testing showed that the primary liquid product, when mixed with any of carbon black, foam glass, silica, chalk or fine broken glass formed a fire-resistant coating that protected the underlying card substrate.

[0121] Accordingly, the invention provides methods of distilling petrochemical-derived plastic (PDP) waste, liquid and semi-solid waterproofing products and compositions, and multiple uses of these products and compositions, e.g. for waterproofing and lubricating applications. Example 6 - Corrosion, weathering and LIV resistance testing of compositions Further testing of the primary and secondary products was carried out to assess (a) their ability to prevent oxidation and corrosion, (b) their ability to protect against weathering, and (c) their UV resistance.

[0122] (a) Protection from oxidation and corrosion damage:

[0123] Accelerated testing to assess resistance to oxidation or corrosion damage that can occur as a result of prolonged exposure to air was carried out by exposing samples to strong acid for a test period of 4 days and assessing the appearance of the sample relative to its original state at the end of the test period.

[0124] An untreated metal control showed evidence of corrosion after the test period. Test cardboard substrates painted with textured paint alone (control) or three coats of the liguid product of the invention were also tested. The control painted substrate was observed to have significant staining but no structural damage. The test painted substrate with three coats of liguid product showed a lesser degree of staining than the control, again with no structural damage.

[0125] An addition test on a tile coated with the liguid product showed no visible damage after 4 days exposure to acid. Water repellency was reduced but still present (contact angle > 60°). Similar results were observed for a tile coated with the secondary wax product.

[0126] (b) Protection from weathering:

[0127] Accelerated testing to assess resistance to weathering or wind damage that can occur as a result of prolonged exposure to the outside environment was carried out by subjecting samples to sand abrasion at 100 rpm for a test period of 4 days and assessing the appearance of the sample relative to its original state at the end of the test period.

[0128] A test substrate (tile) coated with the liguid product showed no visible damage after 4 days. Water repellency was reduced but still present (contact angle > 60°). (c) Protection from UV damage:

[0129] Accelerated testing to assess resistance to UV damage that can occur as a result of prolonged exposure to sunlight was carried out by exposing samples to high energy short wavelength UV light (256nm) for a test period of 4 days and assessing the appearance of the sample relative to its original state at the end of the test period.

[0130] Test cardboard substrates painted with textured paint alone (control) or three coats of the liquid product of the invention were tested. Both control and test samples were unaffected by UV exposure after 4 days.

[0131] An addition test on a tile coated with the liquid product showed no effect after 4 days exposure to UV light. Similar results were observed for a tile coated with the secondary wax product.

[0132] Overall, the primary and secondary products showed good resistance properties and retention of water resistance after exposure to conditions that modelled oxidative and corrosion damage, wind damage and weathering, and prolonged exposure to sunlight.

Claims

Claims1 . A method of distilling petrochemical-derived plastic (PDP) waste comprising: a) heating the PDP waste to form a vapour; and b) collecting and cooling the vapour to obtain a distillate, wherein the distillate is collected as a first fraction and a second fraction, and wherein the PDP waste comprises polyethylene (PE) and / or polypropylene (PP) and has a melting point of 120-220°C.

2. A method according to claim 1 , wherein the PDP waste comprises low density polyethylene (LDPE) and / or high density polyethylene (HDPE).

3. A method according to claim 1 or claim 2, wherein the PDP waste comprises LDPE.

4. A method according to any one of claims 1 -3, wherein the PDP waste comprises at least 70% by weight PE and / or PP.

5. A method according to any one of claims 1 -4, wherein the PDP waste does not comprise polystyrene.

6. A method according to any preceding claim, wherein step a) comprises heating the PDP waste to a temperature of at least 300°C.

7. A method according to any preceding claim, wherein step a) comprises heating the PDP waste to a temperature not exceeding 350°C.

8. A method according to any preceding claim wherein step a) consists of a single heating step.

9. A method according to any preceding claim, wherein step a) is carried out in the absence of a solvent and / or a catalyst.

10. A method according to any preceding claim comprising the further step:c) decolouring and decolouring the first fraction and / or the second fraction by passing each fraction through one or more of sodium bicarbonate, diatomaceous earth and charcoal.11 . A method according to any preceding claim, wherein the first fraction is a liquid.

12. A method according to any preceding claim, wherein the second fraction is a semi-solid gel or paste.

13. A liquid product obtainable by the method of any of claims 1-11.

14. A liquid product according to claim 13, wherein the liquid dries to form a water repellent coating.

15. A semi-solid product obtainable by the method of any of claims 1-10 or 12.

16. A semi-solid product according to claim 15, wherein the semi-solid product has water repellent and lubricating properties.

17. A liquid product according to claim 13 or 14, or a semi-solid product according to claim 15 or 16, that is resistant to UV light and / or fire-resistant.

18. A liquid product according to claim 13 or 14, or a semi-solid product according to claim 15 or 16, that is resistant to oxidation and corrosion.

19. A liquid product according to claim 13 or 14, or a semi-solid product according to claim 15 or 16, that is resistant to weathering.

20. A recycled liquid waterproofing product comprising a mixture of hydrocarbons having a chain length of at least C10.

21. A recycled liquid waterproofing product according to claim 20, wherein the product is derived from PDP waste comprising PE and / or PP.

22. A recycled liquid waterproofing product according to claim 20 or claim 21 , wherein the product dries to form a waterproof coating.

23. A recycled semi-solid waterproofing and lubricating product comprising a mixture of hydrocarbons having a chain length of at least C10.

24. A recycled semi-solid waterproofing and lubricating product according to claim20, wherein the product is derived from PDP waste comprising PE and / or PP.

25. A recycled semi-solid waterproofing and lubricating product according to claim24, wherein the product does not dry when applied to smooth, non-porous surfaces.

26. A composition comprising (a) the liquid product of any of claims 13, 14 or 17- 22, (b) the semi-solid product of any of claims 15-19 or 23-25, or a mixture of (a) and (b).

27. The composition of claim 26, further comprising one or more of carbon black, foam glass dust, silica, chalk and fine broken glass.

28. The composition of claim 26 or claim 27, further comprising a pigment or a curing agent.

29. Use of the composition of any of claims 26-28 to increase the water resistance of a substrate selected from stone, bricks, building blocks, roofing tiles, flat roofs, cement, metal, glass, wood, painted or rendered walls, tarmac, or plastic substrates.

30. Use according to claim 29, wherein the composition is applied to the surface of the substrate.31 . Use according to claim 29, wherein the composition is incorporated into a paint, render, grout, cement or tarmac product.

Images