Bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine

Abstract

A bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine.

Description

TECHNICAL FIELD

[0001] The present disclosure is related to a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, which solvent may be used to remove lubricating oils, carbon deposits, paints, sealants, powder coatings, protective films and adhesives from for example metal tools, machined products, ceramic products and certain plastic products.BACKGROUND ART

[0002] White spirits, also known as mineral turpentine, is a petroleum-derived clear liquid commonly used as an organic solvent to remove lubricating oils from metal tools and machined products or to remove carbon-containing coatings, such as powder coatings, from surfaces. Other alternative cleaning solutions are also predominantly based on solvents made using petrochemical derived products.

[0003] There are cleaning solvents available today, which are called "bio-based" as a portion of their contents is originally from a bio source. Most solvents that are claimed as "bio-based" are, however, determined as such via the mass balance approach and only comprise a certain percentage of bio-based material.

[0004] There is a need for alternative cleaning solutions that are not petrochemical derived but fully bio-based, that could reduce the CO 2 e (carbon dioxide equivalent) footprint of the cleaning solution, and could contribute towards overall reduction in CO 2 e footprint of the final recycled or cleaned metal product.SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide a bio-based cleaning solvent that can be used for example to remove lubricating oils from metal tools and machined products and that could reduce the CO 2 e (carbon dioxide equivalent) footprint of the cleaning solution as compared conventional petrochemical derived cleaning solvents.

[0006] The invention is defined by the appended independent patent claims. Non-limiting embodiments emerge from the dependent claims, the appended drawings, and the following description.

[0007] According to a first aspect there is provided a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the biobased-solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is 5:95 to 95:5 vol.%.

[0008] The bio-based cleaning solvent comprises a mixture of ethyl acetate and crude turpentine, which mixture constitutes at least 95 vol.%, or at least 96 vol.%, or at least 97 vol.%, or at least 98 vol.%, or at least 99 vol.%. The rest may for example be inorganic residues remaining in the turpentine (traces of pulping chemicals, other carbon containing species from the pulping process, e.g. lignin, hemicellulose, cellulose etc.), residues from the production of ethyl acetate, such as ethanol, etc.

[0009] Ethyl acetate (also known as ethyl ethanoate, EtOAc, ETAC, or EA), chemical formula CH 3 CO 2 CH 2 CH 3 or C 4 H 8 O 2 , can be obtained as an output from bio-ethanol processing. Ethyl acetate is considered a green or bio-based solvent as it is derived from renewable resources and has a low environmental impact. It is often used in cleaning products, coatings, paints etc.

[0010] Crude turpentine, or gum turpentine, is obtained as an output from softwood processing. Crude turpentine is composed of terpenes, primarily the monoterpenes alpha-pinene and beta-pinene, along with lesser amounts of carene, camphene, limonene, and terpinolene. Crude turpentine may be used as a solvent and in organic chemistry processes.

[0011] The bio-based cleaning solvent comprising ethyl acetate and crude turpentine is, hence, a cleaning solution that is not petrochemically derived but fully bio-based. The CO 2 e (carbon dioxide equivalent) footprint of the cleaning solvent is low and contributes towards overall reduction in CO 2 e footprint of the final cleaned / recycled product, as compared to petrochemical derived solvents. The bio-based solvent will be much closer to zero GHG (greenhouse gas) impact than previously feasible.

[0012] The solvent can be used to chemically dissolve organic species from a material substrate, for example for removing residues of lubricating mineral oils,carbon deposits, paints, sealants, powder coatings, protective films and adhesives from for example metal tools, machined products, ceramic products and certain plastic products. The solvent targets all carbon-contaminants and is agnostic to the type of material (size, shape, alloy composition etc).

[0013] The combination of ethyl acetate and crude turpentine enhances the solvating properties (penetration and solvation) of the solvent compared to if ethyl acetate or crude turpentine is used as a sole component of the solvent. The crude turpentine has deep penetrating solvation properties and pierces into organic coatings and disrupts local bonds. Crude turpentine is unprocessed and is a heterogeneous mixture of small aromatic organics present in differing concentrations. The presence of these small aromatic organics in the crude turpentine allow for the dissolution of a wide range of complex organic residues. The ethyl acetate has a high solubility for polar compounds and enable efficient solvation of disrupted molecules. A bio-based solvent comprising only ethyl acetate and no crude turpentine will not comprise a sufficiently heterogeneous mixture of small aromatic. A bio-based solvent comprising only crude turpentine and no ethyl acetate will not penetrate complex surface geometries as effectively as with ethyl acetate included. The solvent mixture enables efficient removal of oils and organic coatings such as powder coatings on e.g. aluminium profiles.

[0014] The flash point of ethyl acetate is approximately -4°C. At or above this temperature, the vapour of ethyl acetate can ignite when exposed to an open flame or spark. The presence of the crude turpentine in the solvent increases the flash point of ethyl acetate, reducing the likelihood of ignition of the solvent. In e.g. US8414797B2 is shown that adding terpenes (part of crude turpentine) to methyl acetate (close analogue to ethyl acetate) the flash point increases considerably.

[0015] The above-describe cleaning solvent exhibits both broad spectrum affinity for organic residues and increased penetrating power when compared with petrochemical derived products, thanks to the range of terpene chemistries present in crude turpentine.

[0016] Further, the cleaning solvent has an improved smell, is less flammable and less toxic than conventional petrochemical derived products, making it advantageous from a user experience and health and safety point of view.

[0017] The ratio of ethyl acetate to crude turpentine in the bio-based solvent may be 10:90 to 95:5 vol.%; 15:85 to 95:5 vol.%; 20:80 to 95:5 vol.%; 25:75 to 95:5 vol.%; 30:70 to 95:5 vol.%; 35:65 to 95:5 vol.%; 40:60 to 95:5 vol.%; 45:55 to 95:5 vol.%; 50:50 to 95:5 vol.%; 55:45 to 95:5 vol.%; 60:40 to 95:5 vol.%; 65:35 to 95:5 vol.%; 70:30 to 95:5 vol.%; 75:25 to 95:5 vol.%; 80:10 to 95:5 vol.%; 85:15 to 95:5; 90:10 to 95:5 vol.%; 5:95 to 90:10 vol.%; 5:95 to 85:15 vol.%; 5:95 to 80:20 vol.%; 5:95 to 75:25 vol.%; 5:95 to 70:30 vol.%; 5:95 to 65:35 vol.%; 5:95 to 60:40 vol.%; 5:95 to 55:45 vol.%; 5:95 to 50:50 vol.%; 5:95 to 45:55 vol.%; 5:95 to 40:60 vol.%; 5:95 to 35:65 vol.%; 5:95 to 30:70 vol.%; 5:95 to 25:75 vol.%; 5:95 to 20:80 vol.%; 5:95 to 15:85 vol.%; 5:95 to 10:90 vol.%. In one embodiment, the ratio of acetyl acetate to crude turpentine in the bio-based solvent is 20:80 vol.% to 95:5 vol%.

[0018] According to a second aspect there is provided a use of the bio-based solvent described above for cleaning a substrate surface from oil residues, carbon deposits, lubricants, paints, sealants, powder coatings, protective films and / or adhesives.

[0019] The substrate surface to be cleaned may be a metal or metal alloy surface, a ceramic surface, a polyethylene surface, a polypropylene surface, a polymethyl methacrylate surface, a polyether ether ketone surface, a polyphenylene sulfide surface, a polyamide 6,6 surface, or a polyamide 6 surface.

[0020] In one example, the substrate surface is the surface of aluminium scrap. Electrically driven smelting of secondary aluminium feedstock (i.e. scrap) requires low carbon contamination (≈ <2%). Using this bio-based solvent to clean the aluminium scrap may not only remove GHG emissions during smelting but also allow the use of electrical furnace technologies (e.g. induction furnaces). These two factors will allow a potential zero greenhouse gas production route for aluminium recycling.

[0021] In another example, the bio-based solvent can be used to clean electronics printed circuit board (PCB) recycling.

[0022] According to a third aspect there is provided a method of cleaning a substrate surface using the bio-based solvent described above, the method comprising to immerse the substrate in the bio-based solvent or adding the bio-based solvent to said substrate surface for at least 1 minute.

[0023] The substrate may be immersed in the bio-based solvent / the bio-based solvent may be added to the substrate surface for at least 1 minute, or for at least 10 minutes, or for up to 60 minutes.

[0024] The bio-based solvent may have a temperature of -4 to 35°C when used in the method.

[0025] This temperature range is optimized based on the known flash points of ethyl acetate and crude turpentine, in conjunction with maximising the penetrating power of the solvent while maximising safety.

[0026] The substrate surface may be immersed in the bio-based solvent during agitation.

[0027] Agitation can be used to enhance the cleaning with the bio-based solvent and may be performed e.g. by using ultrasonication, or conventional stirring means, or by using rotating / vibrating metal brushes in contact with the substrate surface, while substrate is submerged in the solvent.

[0028] The substrate surface may be immersed in the bio-based solvent during mechanical processing of the substrate surface.

[0029] To enhance the cleaning with the bio-based solvent the substrate surface may be mechanically processed while being immersed in the bio-based solvent. This may for example be accomplished by using rotating / vibrating brushes (of metal) in contact with the substrate surface.

[0030] The substrate surface may be pre-treated before being immersed in the bio-based solvent or before the bio-based solvent is added to the substrate surface, the pre-treatment step comprising of one or more of: heating and cooling the substrate surface; mechanically processing the substrate surface; exposing the substrate surface to UV light.

[0031] The one or more pre-treatment steps may enhance the cleaning with the bio-based solvent. Heating and cooling the substrate surface may comprise to heat the substrate surface to at least 80°C, then allowing the surface to cool to <35°C, preferably repeating the process a few times. Mechanically processing the substrate surface may comprise to brush the substrate surface with e.g. metal brushes, e.g. at room temperature for up to 60 min. The mechanical processing step may alternatively or additionally comprise mechanical agitation of the substrate in a ball bearing hopper, e.g. at room temperature for up to 60 min. Exposing the substrate surface to UV light may e.g. be performed at room temperature for up to 60 min.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Fig. 1 shows optical microscopy pictures of an aluminium substrate, an aluminium profile, with a powder coating on a surface thereof after exposure to a bio-based cleaning solvent comprising mixtures of ethyl acetate to crude turpentine at different ratios. Fig. 2 shows optical microscopy pictures of aluminium substrate, an aluminium plate, with a plastic film coating on a surface thereof after exposure to a bio-based cleaning solvent comprising mixtures of ethyl acetate to crude turpentine at different ratios. DETAILED DESCRIPTION

[0033] Below is described experiments conducted with a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the bio-based solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is varied between 5:95 to 95:5 vol.%.

[0034] The experiments were performed to investigate the efficacy of using the solvent for removal of organic carbon-species from substrate surfaces. Aluminium samples with organic coatings were exposed to the solvent and afterwards analysed by optical microscopy and total organic carbon analysis.

[0035] The first sample was an aluminium profile with a powder coating on a surface thereof and the second sample was an aluminium plate with a plastic film coating on a surface thereof. Both samples were exposed to the solvent for 10 minutes at room temperature with added agitation through ultrasonication. Three solvent mixture ratios of ethyl acetate:crude turpentine were investigated: 30:70; 50:50 and 70:30 vol.% (solvent comprised 100 vol.% of ethyl acetate and crude turpentine). The results are shown in Figs 1 and 2, as well as in Table 1.

[0036] Fig. 1 shows optical microscopy pictures of the aluminium substrate surface with a powder coating (thickness of coating less than 1 mm) treated with a solvent comprising ethyl acetate and crude turpentine in (a) a ratio of 30:70 vol.%, in (b) a ratio of 50:50 vol.%, and in (c) a ratio of 70:30 vol.%. It was shown that the powder coating was disrupted and delaminated from the aluminium substrate when exposed to a solvent comprising a ratio of ethyl acetate to crude turpentine of 50:50 vol.%. At 70 vol.% ethyl acetate, complete delamination of the powder coating was observed. The coated film could easily be removed with tweezers from the aluminium substrate, as shown in (d) in Fig. 1.

[0037] Fig. 2 shows optical microscopy pictures of the aluminium substrate surface plastic film coating (thickness 30-150 µm) treated with a solvent comprising ethyl acetate and crude turpentine in (a) a ratio of 30:70 vol.%, in (b) a ratio of 50:50 vol.%, and in (c) a ratio of 70:30 vol.%. Exposed aluminium is seen for all samples treated with the solvent in the three detailed ratios, showing the efficacy of coating removal. A reference untreated sample is shown (d) where the plastic film can be seen.

[0038] Quantitative chemical analysis of the aluminium samples was then performed for: sample 1, with powder coating, before and after treatment with the bio-based cleaning solvent, ethyl acetate to crude turpentine having a ratio of 70:30 vol.%; sample 2, with plastic film coating, before and after treatment with the bio-based cleaning solvent, ethyl acetate to crude turpentine having a ratio of 70:30 vol.%; a reference casted aluminium substrate without coating and not treated with the bio-based solvent.

[0039] Residual total organic carbon content (TOC) (%), measured by a total organic carbon analyser, is shown in Table 1. The measurements showed that sample 1 and sample 2 were effectively cleaned of any carbon contaminants, as the residual total carbon content of the treated surfaces equals the total carbon content of the pristine reference aluminium sample. Table 1Sample IDType of organic contaminantTreated with X:Y ratio Ethyl acetate:Crude TurpentineTotal organic carbon (TOC) %TreatedUntreatedAluminium 1Powder coating70:300.02 %3.03 %Aluminium 2Plastic film70:300.01 %0.98 %Reference, casted aluminiumNone-0.01 %

[0040] The bio-based solvent comprising a mixture of ethyl acetate and crude turpentine could efficiently remove organic carbon contaminants from aluminium substrates by a mild exposure at room temperature for just 10 minutes under agitation. Most efficient operation was observed at higher ethyl acetate compositions (i.e. > 50%).

Examples

Embodiment Construction

[0033]Below is described experiments conducted with a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the bio-based solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is varied between 5:95 to 95:5 vol.%.

[0034]The experiments were performed to investigate the efficacy of using the solvent for removal of organic carbon-species from substrate surfaces. Aluminium samples with organic coatings were exposed to the solvent and afterwards analysed by optical microscopy and total organic carbon analysis.

[0035]The first sample was an aluminium profile with a powder coating on a surface thereof and the second sample was an aluminium plate with a plastic film coating on a surface thereof. Both samples were exposed to the solvent for 10 minutes at room temperature with added agitation through ultrasonication. Three solvent mixture ...

TECHNICAL FIELD

[0001] The present disclosure is related to a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, which solvent may be used to remove lubricating oils, carbon deposits, paints, sealants, powder coatings, protective films and adhesives from for example metal tools, machined products, ceramic products and certain plastic products.BACKGROUND ART

[0002] White spirits, also known as mineral turpentine, is a petroleum-derived clear liquid commonly used as an organic solvent to remove lubricating oils from metal tools and machined products or to remove carbon-containing coatings, such as powder coatings, from surfaces. Other alternative cleaning solutions are also predominantly based on solvents made using petrochemical derived products.

[0003] There are cleaning solvents available today, which are called "bio-based" as a portion of their contents is originally from a bio source. Most solvents that are claimed as "bio-based" are, however, determined as such via the mass balance approach and only comprise a certain percentage of bio-based material.

[0004] There is a need for alternative cleaning solutions that are not petrochemical derived but fully bio-based, that could reduce the CO 2 e (carbon dioxide equivalent) footprint of the cleaning solution, and could contribute towards overall reduction in CO 2 e footprint of the final recycled or cleaned metal product.SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide a bio-based cleaning solvent that can be used for example to remove lubricating oils from metal tools and machined products and that could reduce the CO 2 e (carbon dioxide equivalent) footprint of the cleaning solution as compared conventional petrochemical derived cleaning solvents.

[0006] The invention is defined by the appended independent patent claims. Non-limiting embodiments emerge from the dependent claims, the appended drawings, and the following description.

[0007] According to a first aspect there is provided a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the biobased-solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is 5:95 to 95:5 vol.%.

[0008] The bio-based cleaning solvent comprises a mixture of ethyl acetate and crude turpentine, which mixture constitutes at least 95 vol.%, or at least 96 vol.%, or at least 97 vol.%, or at least 98 vol.%, or at least 99 vol.%. The rest may for example be inorganic residues remaining in the turpentine (traces of pulping chemicals, other carbon containing species from the pulping process, e.g. lignin, hemicellulose, cellulose etc.), residues from the production of ethyl acetate, such as ethanol, etc.

[0009] Ethyl acetate (also known as ethyl ethanoate, EtOAc, ETAC, or EA), chemical formula CH 3 CO 2 CH 2 CH 3 or C 4 H 8 O 2 , can be obtained as an output from bio-ethanol processing. Ethyl acetate is considered a green or bio-based solvent as it is derived from renewable resources and has a low environmental impact. It is often used in cleaning products, coatings, paints etc.

[0010] Crude turpentine, or gum turpentine, is obtained as an output from softwood processing. Crude turpentine is composed of terpenes, primarily the monoterpenes alpha-pinene and beta-pinene, along with lesser amounts of carene, camphene, limonene, and terpinolene. Crude turpentine may be used as a solvent and in organic chemistry processes.

[0011] The bio-based cleaning solvent comprising ethyl acetate and crude turpentine is, hence, a cleaning solution that is not petrochemically derived but fully bio-based. The CO 2 e (carbon dioxide equivalent) footprint of the cleaning solvent is low and contributes towards overall reduction in CO 2 e footprint of the final cleaned / recycled product, as compared to petrochemical derived solvents. The bio-based solvent will be much closer to zero GHG (greenhouse gas) impact than previously feasible.

[0012] The solvent can be used to chemically dissolve organic species from a material substrate, for example for removing residues of lubricating mineral oils,carbon deposits, paints, sealants, powder coatings, protective films and adhesives from for example metal tools, machined products, ceramic products and certain plastic products. The solvent targets all carbon-contaminants and is agnostic to the type of material (size, shape, alloy composition etc).

[0013] The combination of ethyl acetate and crude turpentine enhances the solvating properties (penetration and solvation) of the solvent compared to if ethyl acetate or crude turpentine is used as a sole component of the solvent. The crude turpentine has deep penetrating solvation properties and pierces into organic coatings and disrupts local bonds. Crude turpentine is unprocessed and is a heterogeneous mixture of small aromatic organics present in differing concentrations. The presence of these small aromatic organics in the crude turpentine allow for the dissolution of a wide range of complex organic residues. The ethyl acetate has a high solubility for polar compounds and enable efficient solvation of disrupted molecules. A bio-based solvent comprising only ethyl acetate and no crude turpentine will not comprise a sufficiently heterogeneous mixture of small aromatic. A bio-based solvent comprising only crude turpentine and no ethyl acetate will not penetrate complex surface geometries as effectively as with ethyl acetate included. The solvent mixture enables efficient removal of oils and organic coatings such as powder coatings on e.g. aluminium profiles.

[0014] The flash point of ethyl acetate is approximately -4°C. At or above this temperature, the vapour of ethyl acetate can ignite when exposed to an open flame or spark. The presence of the crude turpentine in the solvent increases the flash point of ethyl acetate, reducing the likelihood of ignition of the solvent. In e.g. US8414797B2 is shown that adding terpenes (part of crude turpentine) to methyl acetate (close analogue to ethyl acetate) the flash point increases considerably.

[0015] The above-describe cleaning solvent exhibits both broad spectrum affinity for organic residues and increased penetrating power when compared with petrochemical derived products, thanks to the range of terpene chemistries present in crude turpentine.

[0016] Further, the cleaning solvent has an improved smell, is less flammable and less toxic than conventional petrochemical derived products, making it advantageous from a user experience and health and safety point of view.

[0017] The ratio of ethyl acetate to crude turpentine in the bio-based solvent may be 10:90 to 95:5 vol.%; 15:85 to 95:5 vol.%; 20:80 to 95:5 vol.%; 25:75 to 95:5 vol.%; 30:70 to 95:5 vol.%; 35:65 to 95:5 vol.%; 40:60 to 95:5 vol.%; 45:55 to 95:5 vol.%; 50:50 to 95:5 vol.%; 55:45 to 95:5 vol.%; 60:40 to 95:5 vol.%; 65:35 to 95:5 vol.%; 70:30 to 95:5 vol.%; 75:25 to 95:5 vol.%; 80:10 to 95:5 vol.%; 85:15 to 95:5; 90:10 to 95:5 vol.%; 5:95 to 90:10 vol.%; 5:95 to 85:15 vol.%; 5:95 to 80:20 vol.%; 5:95 to 75:25 vol.%; 5:95 to 70:30 vol.%; 5:95 to 65:35 vol.%; 5:95 to 60:40 vol.%; 5:95 to 55:45 vol.%; 5:95 to 50:50 vol.%; 5:95 to 45:55 vol.%; 5:95 to 40:60 vol.%; 5:95 to 35:65 vol.%; 5:95 to 30:70 vol.%; 5:95 to 25:75 vol.%; 5:95 to 20:80 vol.%; 5:95 to 15:85 vol.%; 5:95 to 10:90 vol.%. In one embodiment, the ratio of acetyl acetate to crude turpentine in the bio-based solvent is 20:80 vol.% to 95:5 vol%.

[0018] According to a second aspect there is provided a use of the bio-based solvent described above for cleaning a substrate surface from oil residues, carbon deposits, lubricants, paints, sealants, powder coatings, protective films and / or adhesives.

[0019] The substrate surface to be cleaned may be a metal or metal alloy surface, a ceramic surface, a polyethylene surface, a polypropylene surface, a polymethyl methacrylate surface, a polyether ether ketone surface, a polyphenylene sulfide surface, a polyamide 6,6 surface, or a polyamide 6 surface.

[0020] In one example, the substrate surface is the surface of aluminium scrap. Electrically driven smelting of secondary aluminium feedstock (i.e. scrap) requires low carbon contamination (≈ <2%). Using this bio-based solvent to clean the aluminium scrap may not only remove GHG emissions during smelting but also allow the use of electrical furnace technologies (e.g. induction furnaces). These two factors will allow a potential zero greenhouse gas production route for aluminium recycling.

[0021] In another example, the bio-based solvent can be used to clean electronics printed circuit board (PCB) recycling.

[0022] According to a third aspect there is provided a method of cleaning a substrate surface using the bio-based solvent described above, the method comprising to immerse the substrate in the bio-based solvent or adding the bio-based solvent to said substrate surface for at least 1 minute.

[0023] The substrate may be immersed in the bio-based solvent / the bio-based solvent may be added to the substrate surface for at least 1 minute, or for at least 10 minutes, or for up to 60 minutes.

[0024] The bio-based solvent may have a temperature of -4 to 35°C when used in the method.

[0025] This temperature range is optimized based on the known flash points of ethyl acetate and crude turpentine, in conjunction with maximising the penetrating power of the solvent while maximising safety.

[0026] The substrate surface may be immersed in the bio-based solvent during agitation.

[0027] Agitation can be used to enhance the cleaning with the bio-based solvent and may be performed e.g. by using ultrasonication, or conventional stirring means, or by using rotating / vibrating metal brushes in contact with the substrate surface, while substrate is submerged in the solvent.

[0028] The substrate surface may be immersed in the bio-based solvent during mechanical processing of the substrate surface.

[0029] To enhance the cleaning with the bio-based solvent the substrate surface may be mechanically processed while being immersed in the bio-based solvent. This may for example be accomplished by using rotating / vibrating brushes (of metal) in contact with the substrate surface.

[0030] The substrate surface may be pre-treated before being immersed in the bio-based solvent or before the bio-based solvent is added to the substrate surface, the pre-treatment step comprising of one or more of: heating and cooling the substrate surface; mechanically processing the substrate surface; exposing the substrate surface to UV light.

[0031] The one or more pre-treatment steps may enhance the cleaning with the bio-based solvent. Heating and cooling the substrate surface may comprise to heat the substrate surface to at least 80°C, then allowing the surface to cool to <35°C, preferably repeating the process a few times. Mechanically processing the substrate surface may comprise to brush the substrate surface with e.g. metal brushes, e.g. at room temperature for up to 60 min. The mechanical processing step may alternatively or additionally comprise mechanical agitation of the substrate in a ball bearing hopper, e.g. at room temperature for up to 60 min. Exposing the substrate surface to UV light may e.g. be performed at room temperature for up to 60 min.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Fig. 1 shows optical microscopy pictures of an aluminium substrate, an aluminium profile, with a powder coating on a surface thereof after exposure to a bio-based cleaning solvent comprising mixtures of ethyl acetate to crude turpentine at different ratios. Fig. 2 shows optical microscopy pictures of aluminium substrate, an aluminium plate, with a plastic film coating on a surface thereof after exposure to a bio-based cleaning solvent comprising mixtures of ethyl acetate to crude turpentine at different ratios. DETAILED DESCRIPTION

[0033] Below is described experiments conducted with a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the bio-based solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is varied between 5:95 to 95:5 vol.%.

[0034] The experiments were performed to investigate the efficacy of using the solvent for removal of organic carbon-species from substrate surfaces. Aluminium samples with organic coatings were exposed to the solvent and afterwards analysed by optical microscopy and total organic carbon analysis.

[0035] The first sample was an aluminium profile with a powder coating on a surface thereof and the second sample was an aluminium plate with a plastic film coating on a surface thereof. Both samples were exposed to the solvent for 10 minutes at room temperature with added agitation through ultrasonication. Three solvent mixture ratios of ethyl acetate:crude turpentine were investigated: 30:70; 50:50 and 70:30 vol.% (solvent comprised 100 vol.% of ethyl acetate and crude turpentine). The results are shown in Figs 1 and 2, as well as in Table 1.

[0036] Fig. 1 shows optical microscopy pictures of the aluminium substrate surface with a powder coating (thickness of coating less than 1 mm) treated with a solvent comprising ethyl acetate and crude turpentine in (a) a ratio of 30:70 vol.%, in (b) a ratio of 50:50 vol.%, and in (c) a ratio of 70:30 vol.%. It was shown that the powder coating was disrupted and delaminated from the aluminium substrate when exposed to a solvent comprising a ratio of ethyl acetate to crude turpentine of 50:50 vol.%. At 70 vol.% ethyl acetate, complete delamination of the powder coating was observed. The coated film could easily be removed with tweezers from the aluminium substrate, as shown in (d) in Fig. 1.

[0037] Fig. 2 shows optical microscopy pictures of the aluminium substrate surface plastic film coating (thickness 30-150 µm) treated with a solvent comprising ethyl acetate and crude turpentine in (a) a ratio of 30:70 vol.%, in (b) a ratio of 50:50 vol.%, and in (c) a ratio of 70:30 vol.%. Exposed aluminium is seen for all samples treated with the solvent in the three detailed ratios, showing the efficacy of coating removal. A reference untreated sample is shown (d) where the plastic film can be seen.

[0038] Quantitative chemical analysis of the aluminium samples was then performed for: sample 1, with powder coating, before and after treatment with the bio-based cleaning solvent, ethyl acetate to crude turpentine having a ratio of 70:30 vol.%; sample 2, with plastic film coating, before and after treatment with the bio-based cleaning solvent, ethyl acetate to crude turpentine having a ratio of 70:30 vol.%; a reference casted aluminium substrate without coating and not treated with the bio-based solvent.

[0039] Residual total organic carbon content (TOC) (%), measured by a total organic carbon analyser, is shown in Table 1. The measurements showed that sample 1 and sample 2 were effectively cleaned of any carbon contaminants, as the residual total carbon content of the treated surfaces equals the total carbon content of the pristine reference aluminium sample. Table 1Sample IDType of organic contaminantTreated with X:Y ratio Ethyl acetate:Crude TurpentineTotal organic carbon (TOC) %TreatedUntreatedAluminium 1Powder coating70:300.02 %3.03 %Aluminium 2Plastic film70:300.01 %0.98 %Reference, casted aluminiumNone-0.01 %

[0040] The bio-based solvent comprising a mixture of ethyl acetate and crude turpentine could efficiently remove organic carbon contaminants from aluminium substrates by a mild exposure at room temperature for just 10 minutes under agitation. Most efficient operation was observed at higher ethyl acetate compositions (i.e. > 50%).

Examples

Embodiment Construction

[0033]Below is described experiments conducted with a bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the bio-based solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is varied between 5:95 to 95:5 vol.%.

[0034]The experiments were performed to investigate the efficacy of using the solvent for removal of organic carbon-species from substrate surfaces. Aluminium samples with organic coatings were exposed to the solvent and afterwards analysed by optical microscopy and total organic carbon analysis.

[0035]The first sample was an aluminium profile with a powder coating on a surface thereof and the second sample was an aluminium plate with a plastic film coating on a surface thereof. Both samples were exposed to the solvent for 10 minutes at room temperature with added agitation through ultrasonication. Three solvent mixture ...

Claims

1. A bio-based cleaning solvent comprising a mixture of ethyl acetate and crude turpentine, wherein the ethyl acetate and crude turpentine mixture constitutes at least 95 vol.% of the biobased-solvent and wherein a ratio of ethyl acetate to crude turpentine in the bio-based solvent is 5:95 to 95:5 vol.%.

2. Use of the bio-based solvent of claim 1 for cleaning a substrate surface from oil residues, carbon deposits, lubricants, paints, sealants, powder coatings, protective films and / or adhesives.

3. Use of the bio-based solvent according to claim 2, wherein the substrate surface to be cleaned is a metal or metal alloy surface, a ceramic surface, a polyethylene surface, a polypropylene surface, a polymethyl methacrylate surface, a polyether ether ketone surface, a polyphenylene sulfide surface, a polyamide 6,6 surface, or a polyamide 6 surface.

4. Method of cleaning a substrates surface using the bio-based solvent of claim 1, comprising immersing the substrate in the bio-based solvent for at least 1 minute.

5. The method of claim 4, wherein the bio-based solvent has a temperature of -4 to 35°C.

6. The method of claim 4 or 5, wherein the substrate surface is immersed in the bio-based solvent during agitation.

7. The method of any of claims 4 to 6, wherein the substrate surface is immersed in the bio-based solvent during mechanical processing of the substrate surface.

8. The method of any of claims 4-7, wherein the substrate surface is pre-treated before being immersed in the bio-based solvent or the bio-based solvent is added to the substrate surface, the pre-treatment step comprising one or more of: - heating and cooling the substrate surface; - mechanically processing the substrate surface; - exposing the substrate surface to UV light.

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