Polyethylene terephthalate-based adhesive repair patch for anticorrosive coatings, method for producing same and use thereof

Abstract

The present invention relates to a method for obtaining anti-corrosion adhesive repair patches made from discarded PET bottles using a phase inversion technique by complete precipitation of recycled PET. The resulting film can be used as an adhesive patch and can be applied to any metal surface, painted or unpainted, without any surface treatment, thereby removing a step from the painting process and making the method disclosed in this invention low cost. The adhesive repair patch is easy to apply by simply removing the liner and applying the patch to the structure, does not require specialized labor, has a durability of at least two years, and may or may not be removable for maintenance painting. For removal, the adhesive PET patch is easily removed using conventional hydroblasting methods.

Description

[Technical Field]

[0001] The present invention is part of the field of chemical engineering, more particularly the field of materials and metallurgy, and describes an anti-corrosion repair agent based on recycled thermoplastic materials such as polyethylene terephthalate (PET) for temporary protection against corrosion of damaged paint systems, which repair agent can be applied as an adhesive and in liquid or solid form. [Background technology]

[0002] Carbon steel is one of the most widely used materials in the world due to its versatile mechanical properties and availability. Therefore, this metal is susceptible to corrosion under typical conditions of use, such as exposure to atmospheres containing humidity and pollutants, and its wear is therefore the subject of significant analysis. For example, in the petroleum industry, corrosion exists in various parts of the process, including production, transportation, storage, and refining, resulting in billions of dollars of costs. In addition to costs, accidents in the petrochemical industry can be catastrophic in terms of both loss of life and environmental impact, so the importance of controlling corrosion in these industries is clear.

[0003] Of these corrosion inhibition methods, the use of organic coatings is one of the most widely used in the industry due to their relatively low cost and ability to function well in preventing corrosion. These coatings work by forming a barrier between the environment and the elements to be protected, preventing aggressive agents from contacting the metal and initiating wear mechanisms. To achieve this, the barrier formed must be impermeable to these agents to effectively ensure this isolation.

[0004] However, it is common for deteriorated coatings to be observed prior to scheduled preventative maintenance, and in these cases, intervention must be performed so that protection is repaired in those areas. For this intervention to be efficient in protecting against corrosion, good surface preparation and the use of appropriate chemical products are required, in addition to good technical training of the interventionist. It can therefore be appreciated that this stage can be costly as it relies on quality inputs, qualified labor and time to ensure the integrity of the structure again.

[0005] Both protection systems require surfaces that are free of oil, grease, oxides, salts and other contaminants, and in the case of polymer systems, film fixation is highly dependent on the substrate's roughness profile, so maintenance teams must do a good job regardless of the repair process employed.

[0006] The specificity of each of these systems makes the repair process costly, due to the various steps that affect the total run time, as well as the need to hire a prepared and qualified execution team to ensure that the applied repair system shows its best performance. However, in practice this does not occur because the difficulty of accessing the damaged area, coupled with operational errors, can lead to premature degradation of the applied repair material, thereby compromising the integrity of the entire paint system and metal structure.

[0007] Currently, high performance coating systems undergo a series of several step repair maintenance procedures, which are time consuming and costly. Additionally, despite being a renewable material, 240,000 tonnes of polyethylene terephthalate were improperly disposed of in 2015, highlighting the need to find new uses for this material to avoid environmental problems. PET has good requirements for use as an anti-corrosive coating because it has low permeability to gases and water and good chemical resistance.

[0008] Considering the situation outlined above, the need to make better use of discarded PET is undeniable, and in this sense the present invention offers several advantages by developing a repair system based on polyethylene terephthalate obtained from post-consumer materials for painted structures. The material acts as a rust inhibitor, is applied to damaged areas as a coating, is inexpensive to acquire, and helps the environment by facilitating the recycling of discarded PET. [Prior Art]

[0009] As shown below, there are several state of the art documents describing anti-corrosion repair agents based on recycled polyethylene terephthalate for corrosion protection of paint systems.

[0010] Patent document BRPI 0404257-3, entitled "PROCESSO DE OBTENCAO ADESIVOS POLIURETANICOS E ADESIVOS POLIURETANICOS ASSIM OBTIDOS" (Process for Obtaining Polyurethane Adhesives and Polyurethane Adhesives Obtained Thereby), refers to polyurethane adhesives and polyester polyols obtained by a chemical recycling process of PET materials that reduces the number of steps and uses a greater amount of recycled PET in the preparation of the polyols used in the manufacture of polyurethanes.

[0011] However, said patent uses a glycolytic polymerization process consisting in reducing the molar mass of PET using glycols, resulting in the formation of polyesters, and this entire process is called chemical recycling. It should be noted that in comparison to the above document, the present invention does not use a method for decomposing packaging made from PET to produce by-products. In contrast, the present invention consists of dissolving post-consumer PET after it has been reduced to flake form (mechanical processing). The document chemically recycles PET and uses only some of its by-products (polyols, polyesters), which are then reacted with isocyanates to produce polyurethane glue (the adhesive part of the tape). Thus, the object of said document is to produce the adhesive part of an adhesive tape, whereas the model disclosed in the present invention represents a support for this glue, i.e. they are completely different products. Additionally, the present invention utilizes all chemicals present in the composition of PET packaging.

[0012] The scientific paper, titled "POLY(ETHYLENE TEREPHTHALATE) PHASE INVERSION MEMBRANES: THERMODYNAMICS AND EFFECTS OF A POOR SOLVENT ON THE MEMBRANE CHARACTERISTICS," mentions PET as a globally established polymer used in the manufacture of membranes. The paper prepares PET membranes using a phase inversion technique and characterizes the phase separation phenomenon and the performance of membranes produced under different solution conditions.

[0013] However, the work developed by said literature aimed to produce membranes derived from virgin PET for application in separation processes. The process used according to the present invention exhibits differences relative to the processes disclosed by the above references which result in different products.

[0014] The product synthesized in the said document is intended to produce a membrane, and for this purpose the material used must be porous, whereas the anticorrosion barrier must be pore-free, which does not apply to the proposed patent.

[0015] Therefore, to avoid the porosity problem, the present invention performs the precipitation process in ambient air for 30 minutes before using the phase inversion technique in a non-solvent solution (distilled water).

[0016] After precipitation of PET, a phase inversion process was carried out in distilled water on a glass surface. Immersion of the PET solution in water without precipitation in air, as proposed by the literature, produces a porous membrane, a product completely different from that obtained by the present invention, according to FIG. 1.

[0017] Additionally, the present invention addresses the need to neutralize the PET film after the phase inversion process, thus removing traces of residual acid from the manufacturing process.

[0018] Another important factor that differentiates the present invention from the above-mentioned literature is the addition of dibutyl phthalate in the range of 10% to 30% (v / v) relative to the volume of the PET solution. Furthermore, the surprising use of adding plasticizers to PET solutions to produce films with high flexibility stands out. The use of the addition of plasticizers in the present invention aims to correct problems such as high stiffness and low flexibility of the film, since this is an essential property for the production of adhesive PET in order not to limit its application to surfaces with flat shapes only.

[0019] Note that without the addition of plasticizer, the film becomes brittle within a few hours and becomes impossible to apply, as shown in Figure 2.

[0020] The scientific article entitled "PLASTICIZER EFFECTS ON PHYSICAL-MECHANICAL PROPERTIES OF SOLVENT CAST SOLUPLUS® FILMS" specifically refers to the characterization of the mechanical properties of Soluplus® using four different plasticizers. The plasticizers selected were polyethylene glycol 6, triethyl citrate, propylene glycol and glycerin, which were studied at three different levels (15%, 20% and 25% w / w). The results demonstrated that these four plasticizers could increase the elongation and toughness of the films while decreasing the glass transition temperature, tensile strength, and Young's modulus. Among the plasticizers tested, polyethylene glycol 6 showed the greatest change in the mechanical properties studied.

[0021] However, said document adds different plasticizers to polymers that do not belong to the terephthalate class. It is noteworthy that the use of plasticizers is widely used in the literature among polymers undergoing thermomechanical processing, as it improves the physical and mechanical properties of the final product by lowering the glass transition temperature (Tg). In this case, the study does not produce a material from the modification of this polymer by the addition of a plasticizer, but merely examines the effect of this addition on the physical and mechanical properties of the polymer under study. Furthermore, the work carried out by said literature is not comparable to the work proposed by the present invention, since its focus is not to modify the physical and mechanical properties of post-consumer PET, but in fact its aim is to completely solubilize this material to form a film which can then be applied as a support for an adhesive. In summary, the present invention and the above-mentioned document may be merely comparable if they disclose the modification of the structure of post-consumer PET by adding plasticizers and then evaluating its properties, whereas the present invention is directed to the production of new products from post-consumer PET.

[0022] The scientific articles entitled (A) "PROPERTIES OF POST-CONSUMER POLYETHYLENE TEREPHTHALATE COATING MECHANICALLY DEPOSITED ON MILD STEELS" and (B) "PRODUCTION AND CHARACTERIZATION OF THERMALLY SPRAYED POLYETHYLENE TEREPHTHALATE COATINGS" refer, respectively, to a used PET anti-corrosion coating applied by an industrial press to carbon steel and a thermally sprayed polymer (PET) coating applied by a low-velocity flame spray technique to 1020 steel as protection against corrosion and abrasion.

[0023] However, these documents relate to the direct deposition of finely divided PET powder onto the surface of steel using thermal spray and pressing techniques, respectively. In neither study did post-consumer PET dissolve in organic reagents to produce a solution or produce an adhesive film.

[0024] Reference (B) uses a ball mill apparatus and processes PET using a subsonic combustion torch-type thermal spray apparatus operating under high pressure conditions. Therefore, it was by this method that PET powder was deposited onto the surface of low carbon steel. In addition, it was necessary to preheat the substrate onto which the film was deposited in order to allow the PET powder to adhere better. In short, this is an expensive and time consuming process for applying a coating. Next, reference (A) deposits finely divided post-consumer PET powder onto the surface of low carbon steel. However, the production of PET powder undergoes a heat treatment before the grinding process, and its deposition onto a substrate is carried out by a pressing process. Regarding the pressing process, it can be said that the PET powder was placed on the steel and then hot pressed (T=260° C.) on the surface to attach the film to the surface.

[0025] After elucidating the two processes, it can be seen that none of the techniques used by the above documents are similar to the technique proposed by the present invention.

[0026] The scientific paper, titled "RECYCLING WASTE POLYESTER VIA MODIFICATION WITH A RENEWABLE FATTY ACID FOR ENHANCED PROCESSABILITY," discusses the use of renewable TOFA fatty acids as a modifier for recycled PET. For this purpose, PET was compounded with TOFA at different concentrations and extruded at 240 °C. Characterization shows that the melting and recrystallization temperatures of PET shift to lower temperatures and the glass transition temperature decreases from 91°C to 65°C. The addition of TOFA also creates defects in the crystalline phase, retarding recrystallization, an important processing parameter. The change in morphology of the plasticized PET reduces and stabilizes the viscosity. These results suggest a potential route for reusing PET waste as high-performance polymer fibers.

[0027] However, said document aims to replace aggressive additives used in the manufacturing process of packaging made from PET, mainly in the moulding stage (for example to reduce the extrusion temperature). Thus, the document identifies the fatty acid TOFA as a potential renewable plasticizer for post-industrial PET resins, so that moldability can be achieved at lower temperatures. Furthermore, the document seeks to modify the composition of the raw material, in this case PET, which is outside the scope of the present invention.

[0028] The object of the present invention is to produce an adhesive made from post-consumer bottles, while the object of said document is to lower the melting temperature of PET so that temperatures above 260°C are not required in the recycling process, for example.

[0029] The article, titled "What is the Best Adhesive for Bonding PVC Plastic?", refers to PET as a polyester-based thermoplastic material. PET is a lightweight, strong, inert material that is easy to transport and recyclable. PET is extremely versatile and can be used to make food and beverage packaging, disposable medical devices, and industrial films and wraps.

[0030] However, the document is a newsletter from a British chemical company, one of whose divisions is engaged in the manufacture and sale of adhesives. The newsletter in question lists some of PET's properties and its uses, which are numerous. However, the newsletter only instructs consumers on the importance of surface preparation when attaching PET parts and which glues manufactured by the supplier can be used.

[0031] Therefore, no similarities were found between the newsletter and the present invention, as the process of reusing PET bottles for anti-corrosion purposes without significantly impairing the properties of the PET bottles was not addressed. Summary of the Invention

[0032] The present invention first aims to propose a process for producing an anti-corrosion repair adhesive based on recycled PET for the temporary protection of damaged paint systems.

[0033] In a second embodiment, the present invention refers to an adhesive film obtained by said process. The films exhibit good ductility and flexibility, and additionally have properties such as low permeability to water and gases and good chemical resistance.

[0034] Finally, in a third embodiment, the invention proposes the use of said adhesive film as an anti-corrosion repair system for painted structures, to be applied to the site as a coating that forms a barrier between the environment and the elements to be protected, preventing aggressive chemicals from contacting the metal and initiating wear mechanisms. [Brief explanation of the drawings]

[0035] In order that the objects of the present invention may be fully and completely visualized, reference is made to the following drawings:

[0036] [Figure 1] The following are examples of porous films that cannot be used for rust prevention purposes.

[0037] [Figure 2] (a) shows the unformulated PET film fresh from production, and (b) shows the unformulated PET film after several hours on the bench, showing its brittleness.

[0038] [Figure 3] Shows application of acrylic glue to PET film to produce adhesive.

[0039] [Figure 4] (a) shows the PET solution as prepared, and (b) shows the PET solution applied to stainless steel.

[0040] [Figure 5] (a) shows the PET adhesive, (b) shows the PET adhesive peeled from the liner, (c) shows the low carbon steel substrate containing the PET adhesive, and (d) shows the PET adhesive applied to the steel surface.

[0041] [Figure 6] 1 shows a flowchart of all stages of the PET adhesive manufacturing process. DETAILED DESCRIPTION OF THE INVENTION

[0042] In a first embodiment, the present invention relates to a process for obtaining an anti-corrosion adhesive based on recycled thermoplastic materials for the temporary protection of damaged paint systems.

[0043] The process, as shown in the flowchart of FIG. 6, includes the following steps: I. Disinfecting the recycled thermoplastic material with water, soap, and a sodium hypochlorite disinfectant solution having a concentration of 0.1% to 2.5%; II. cutting the recycled thermoplastic material into slices each having dimensions that may vary from 0.5 cm x 0.5 cm to 3.0 cm x 3.0 cm; III. Dissolving the flakes in a solution containing a strong carboxylic acid and an organic solvent in a ratio of 15% to 35% (m / v) with an acid / solvent ratio ranging from 5 / 95 (% v / v) to 95 / 5 (% v / v) to produce a film; IV. Stirring the solution obtained in (III) at room temperature until completely dissolved; V. Slowly adding a plasticizer at a concentration ranging from 10 to 50% (v / v); VI. Dissolving all of the plasticizer until a mixture is formed; VII. subjecting the mixture to an ultrasonic bath for 5 to 15 minutes; VIII. Place the mixture in (VII) on a glass plate and leave the system in the atmosphere for 30 to 90 minutes; IX. Waiting for partial precipitation of the thermoplastic material; X. Performing a phase inversion technique by immersing the glass plate in a non-solvent bath of distilled water; XI. Applying a layer of permanent adhesive glue using an extender and protecting it with a siliconized paper liner.

[0044] The repair adhesive may optionally be derived from any recycled thermoplastic material selected from the group consisting of poly(propylene), poly(ethylene), poly(vinyl chloride), poly(urethane), poly(styrene), poly(ethylene vinyl acetate) and poly(methyl methacrylate), preferably poly(ethylene terephthalate).

[0045] Dissolution of the thermoplastic material can be carried out in different proportions of strong carboxylic acid and solvent, i.e., 5 / 95 (% v / v) to 95 / 5 (% v / v). The strong carboxylic acid may be selected from trichloroacetic acid, 1,1,1,3,3,3-hexafluoro-2-propanol (HIFP), preferably trifluoroacetic acid (TFA) is used. The organic solvent may be selected from acetone, toluene, xylene, phenol and carbon tetrachloride, preferably dichloromethane (DCM) is used. In addition, the ratio of the thermoplastic material, preferably PET, to the strong carboxylic acid solution and solvent can vary from 10 / 90 (m / v%) to 40 / 60 (m / v%).

[0046] Additionally, different classes of plasticizers may alternatively be used for polymer synthesis, with the following options being among the options: - adipic acid derivatives (di-n-hexyl adipate (DHA), heptylnonyl adipate (79A), di-2-ethylhexyl adipate (DOA), diisodecyl adipate (DIDA), diisononyl adipate (DINA); - azelaic acid derivatives (di-2-ethylhexyl azelate (DOZ); - Benzoic acid derivatives (diethylene glycol dibenzoate, dipropylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol isobutyrate benzoate); - citric acid derivatives (tri-n-butyl citrate, acetyltri-n-butyl citrate); - Epoxy derivatives (epoxidized soybean oil (ESO), epoxidized linseed oil (ELO), 2-ethylhexyl epoxythalate); - glycol derivatives (diethylene glycol dipelargonate, triethylene glycol di-2-di-2-methylbutyrate); - Hydrocarbons (hydrogenated terphenyls, chlorinated paraffins (52% CI by weight); - softallic acid derivatives (di-2-ethylhexyl isophthalate); - oleic acid derivatives (butyl oleate); - Phosphoric acid derivatives (tri-2-ethylhexyl phosphate (TOP), triphenyl phosphate (TPP), tricresyl phosphate (TCP), 2-ethylhexyl diphenyl phosphate, isodecyl diphenyl phosphate); - Phthalic acid derivatives (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyloctyl phthalate (BOP), diisohexyl phthalate (DHP), diisoheptyl phthalate (DIHP), heptylnonyl phthalate (79P), heptylnonylundecyl phthalate (711P), diisooctyl phthalate (DlOP), dl-2-ethylhexyl phthalate (DOP), (n-hexyl, octyl, decyl) phthalate (610), (n-octyl, decyl) phthalate (81OP), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), ditridecyl phthalate (dltridecyl) phthalate) (DTDP), butyl benzyl phthalate (BBP), alkyl benzyl phthalate, Santicizer® 261); - Ricinoleic acid derivatives (methyl ricinoleate, n-butyl acetylricinoleate, castor oil); - Sebacic acid derivatives (di-2-ethylhexyl sebacate (DOS)); - stearic acid derivatives (n-butyl stearate); - Sucrose derivatives (sucrose acetate isobutyrate (SAIB)); sulfonic acid derivatives ((o,p)-toluenesulfonamide, N-ethyl-(o,p)-toluenesulfonamide, phenol alkylsulfonates and creosol (Mesamoll®)); - terephthalic acid derivatives (bis(2-ethylhexyl) terephthalate (DOTP); - Trimellitic acid derivatives (tris(2-ethylhexyl) trimelllate (TO™), heptylnonyl trimellate (79™), triisononyl trimellate (TINT™); polyesters such as adipic acid polyester (mol wt 6000), Paraplex® G-40, adipic acid polyester (mol wt 2000), Santiclzer® 334F, azeiic acid polyester (mol wt 2200), Platolein (copyright) 9720, sebacic acid polyester (mol wt 8000), Paraplex® G-25); and - Terpenes and derivatives (camphor, hydrogenated methyl esters of rosin).

[0047] The glues used in the adhesive layer may be made from formulations based on elastomers such as natural rubber, butyl rubber, nitrile rubber and styrene-butadiene rubber, acrylates or silicones. The acrylic glue is applied to the adhesive film using a Bird type extender. This device ensures uniform application and controlled thickness of glue onto the adhesive film. Figure 3 shows how the Bird extender works when applying glue to adhesive film. After the acrylic glue is applied, a liner is applied, which serves to protect the glue and ensures that the glue will maintain its properties until it is time to use it.

[0048] Thus, in a second embodiment, the present invention describes the resulting repair adhesive. The adhesive is available as a repair system for painted structures and can be applied to the site as a coating that forms a barrier between the environment and the element to be protected, preventing aggressive chemicals from contacting the metal and initiating wear mechanisms. To this end, the barrier formed is impermeable to these agents and ensures effective thermal insulation.

[0049] These adhesives are ductile and flexible, have low permeability to water and gas, and have excellent chemical resistance, making them suitable for use as anti-corrosion coatings. The adhesive exhibits low film porosity as seen by scanning electron microscopy (SEM) and water absorption testing. In addition, they have good thermal stability up to 150° C. and show no chemical decomposition in PET after dissolving in TFA, as confirmed by Fourier transform infrared (FTIR) bands.

[0050] It is worth noting that adhesive films are relatively inexpensive to obtain, work well to prevent corrosion, and have a durability of at least two years.

[0051] Finally, in a third embodiment, the present invention proposes the use of said adhesive as an anti-corrosion repair agent.

[0052] The resulting rust preventative repair agent can be applied to any metal surface, whether painted or not, in land and sea areas. The present invention proposes application in liquid form as a spray or in solid form in the form of an adhesive tape.

[0053] When applied in liquid form, the dissolved thermoplastic material solution is simply deposited on the metal surface and allowed to stand for approximately 15 minutes for the polymer film to form. Thus, the liquid application of the solution consists of the direct application of a solution composed of a strong carboxylic acid and a thermoplastic material dissolved in an organic solvent.

[0054] This solution is therefore a base solution for the production of varnishes, which can be applied to various substrates by spraying (for example using a paint gun) or with a brush. Furthermore, by adding a thickener, the solution can be used as a gel, which can be applied to a surface using a brush.

[0055] Solid application consists of preparing the adhesive and applying it directly to the metal substrate according to the process described in this invention with the addition of a glue layer and a silicone paper liner to protect the adhesive. It is worth noting that the function of the liner, which is treated paper, is to ensure the self-adhesiveness of the adhesive in addition to protecting it from contamination.

[0056] Removal of the PET adhesive can be done manually or by abrasive blasting, for example hydroblasting or metal oxide blasting.

[0057] To demonstrate this possibility, the invention will now be described in more detail with reference to examples. It should be noted that the following description is intended only to clarify understanding of the proposed invention and to disclose embodiments of the invention in more detail, but is not intended to limit the invention thereto. Therefore, variations similar to those in the examples are within the scope of the present invention. [Example] Examples of PET-based embodiments

[0058] In this example, used PET bottles were disinfected with water, soap and 0.1% sodium hypochlorite disinfectant to obtain a polyethylene terephthalate-based support material for anti-corrosion coatings. After the bottles were sanitized, the bottom and top of each bottle were removed.

[0059] The cut bottle was further chopped into slices with approximate dimensions of 1 cm x 1 cm. Next, 15 g of this PET was dissolved in a solution containing trifluoroacetic acid (TFA) and dichloromethane (DCM) in a 50 / 50 (% v / v) ratio to produce a PET film.

[0060] The solution was allowed to stand at room temperature for 24 hours with stirring. Then, the plasticizer dibutyl phthalate was slowly added at a concentration of 20% (v / v). After the plasticizer was completely dissolved, the mixture was subjected to an ultrasonic bath for 15 minutes to remove air bubbles that could affect the structure of the repair support material.

[0061] The solution was then placed in a glass plate, and the system was left standing in air for 30 minutes to allow the PET contained in the solution to partially precipitate. After a resting period, a phase inversion technique was performed to produce a film by complete precipitation of the PET. The phase inversion technique consists of immersing a glass plate containing the PET solution in a non-solvent bath, such as distilled water.

[0062] It should be noted that precipitation of the polymer in solution occurs more quickly if the immersion occurs immediately after its deposition on the substrate. Precipitating the polymer in two stages requires more time for controlled evaporation of the organic solvents (trifluoroacetic acid and dichloromethane) during the settling period. This evaporation step in air involves the evaporation of toxic acids that are harmful to human health and must therefore be carried out in an environment with an exhaust fan.

[0063] The function of the plasticizer is to modify the polymer matrix (in this case the PET matrix) so that small molecules can be trapped between its chains, breaking the intermolecular bonds and creating separation between the chains. In this way, films made from this material become more ductile and flexible.

[0064] A layer of permanently tacky acrylic glue was applied to the surface of the PET film using an extender and protected with a siliconized paper liner.

[0065] The glue used as adhesive is an acrylic-styrene copolymer composed of acrylic acid monomers and styrene monomers, such as a product that can be found on the market. The acrylic glue is applied to the film using a Bird extender. This equipment ensures uniform application and controlled thickness of glue onto the PET film. Figure 3 shows how the Bird extender works when applying glue to PET film. After the acrylic glue is applied, a liner is applied which acts as a protector for the glue and ensures that the glue maintains its properties until it is time to use it.

[0066] The liquid application of PET solution consisted of the direct application of a solution composed of PET dissolved in trifluoroacetic acid and dichloromethane. A solution containing 20% ​​(m / m) PET dissolved in 50% (v / v) dichloromethane (DCM) and 50% (v / v) trifluoroacetic acid (TFA) can be used. It is important to note that this solution does not contain any tackifying resins, plasticizers or glues in its composition. This solution is a base solution for producing varnishes, which can be applied to various substrates by spraying with a paint gun or with a brush on metal surfaces to form a polymer film after 5 minutes. It can also be used as a gel that is applied to the surface with a brush.

[0067] FIG. 4A shows a PET solution with a composition of 20% (m / m) PET, 50% (v / v) TFA, and 50% (v / v) DCM. FIG. 4B shows the PET solution applied to a stainless steel surface using a brush.

[0068] Solid application consists of preparing a PET adhesive and applying it directly to the metal substrate, following the steps of the method described in this invention for producing a PET film with an added layer of acrylic glue, followed by the application of a silicone paper liner to protect the adhesive.

[0069] Liners are materials commonly found on the market for use with adhesives. FIG. 5 shows the PET-based adhesive before application (FIG. 5A) and after the liner has been removed (FIG. 5B). FIG. 5C shows the steel substrate before a film is applied to its surface, and FIG. 5D shows the steel substrate after an adhesive has been applied to its surface.

[0070] Those skilled in the art will understand the knowledge presented and be able to reproduce the invention in the illustrated embodiments and other variations that fall within the scope of the appended claims.

Claims

1. Steps below: I. Disinfecting the recycled thermoplastic material with water, soap, and a sodium hypochlorite disinfectant solution at a concentration of 0.1% to 2.5%; II. Cutting the recycled thermoplastic material into slices, each having dimensions that may vary from 0.5 cm x 0.5 cm to 3.0 cm x 3.0 cm; III. Dissolving the flakes in a solution containing a strong carboxylic acid and an organic solvent in a ratio of 15% to 35% (m / v) with an acid / solvent ratio ranging from 5 / 95 (% v / v) to 95 / 5 (% v / v) to produce a film, wherein the ratio of the thermoplastic material to the strong carboxylic acid solution and solvent can vary from 10 / 90 (m / v%) to 40 / 60 (m / v%); IV. Stirring the solution obtained in (iv) at room temperature until the materials are dissolved; V. Slowly adding a plasticizer at a concentration ranging from 10 to 50% (v / v); VI. Dissolving all of the plasticizer until a mixture is formed; VII. Subjecting the mixture to an ultrasonic bath for 5 to 15 minutes; VIII. Place the mixture from (VII) on a glass plate and allow the system to stand in the atmosphere for 30 to 90 minutes; IX. Waiting for partial precipitation of the thermoplastic material; X. Performing a phase inversion technique by immersing the glass plate in a non-solvent bath of distilled water; XI. A process for producing a repair adhesive, comprising the steps of applying a layer of permanently tacky glue using an extender and protecting it with a siliconized paper liner.

2. 2. The manufacturing process according to claim 1, characterized in that in step (I), the thermoplastic material is selected from the group consisting of poly(propylene), poly(ethylene), poly(vinyl chloride), poly(urethane), poly(styrene), poly(ethylene vinyl acetate) and poly(methyl methacrylate), preferably poly(ethylene terephthalate).

3. 10. The manufacturing process of claim 1, wherein step (III) can be carried out with different proportions of the strong carboxylic acid, the organic solvent, and the thermoplastic material.

4. 4. The manufacturing process according to claim 3, characterized in that the strong carboxylic acid used can be selected from the group consisting of trifluoroacetic acid, trichloroacetic acid and 1,1,1,3,3,3-hexafluoro-2-propanol (HIFP).

5. 4. The manufacturing process according to claim 3, characterized in that the organic solvent used can be selected from the group consisting of acetone, dichloromethane, toluene, xylene, phenol and carbon tetrachloride.

6. 6. A manufacturing process according to claim 4 or 5, characterized in that trifluoroacetic acid (TFA) and dichloromethane (DCM) are preferably used.

7. In step (V), different classes of plasticizers can be used, the different classes of plasticizers being: adipic acid derivatives (di-n-hexyl adipate (DHA), heptylnonyl adipate (79A), di-2-ethylhexyl adipate (DOA), diisodecyl adipate (DIDA), diisononyl adipate (DINA); azelaic acid derivatives (di-2-ethylhexyl azelate (DOZ); benzoic acid derivatives (diethylene glycol dibenzoate, dipropylene glycol dibenzoate, 2,2,4-trimethyl-1,3-pentanediol isobutyrate benzoate); citric acid derivatives (tri-n-butyl citrate, acetyltri-n-butyl citrate); - epoxy derivatives (epoxidized soybean oil (ESO), epoxidized linseed oil (ELO), 2-ethylhexyl epoxythalate); glycol derivatives (diethylene glycol dipelargonate, triethylene glycol di-2-di-2-methylbutyrate); - hydrocarbons (hydrogenated terphenyls, chlorinated paraffins (52% CI by weight); isophthalic acid derivatives (di-2-ethylhexyl isophthalate); - oleic acid derivatives (butyl oleate); phosphoric acid derivatives (tri-2-ethylhexyl phosphate (TOP), triphenyl phosphate (TPP), tricresyl phosphate (TCP), 2-ethylhexyl diphenyl phosphate, isodecyl diphenyl phosphate); - phthalic acid derivatives (dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), butyloctyl phthalate (BOP), diisohexyl phthalate (DHP), diisoheptyl (DIHP), heptylnonyl phthalate (79P), heptylnonylundecyl phthalate (711P), diisooctyl phthalate (DlOP), dl-2-ethylhexyl phthalate (DOP), (n-hexyl, octyl, decyl) phthalate (610), (n-octyl, decyl) phthalate (81OP), diisodecyl (DIDP), diundecyl phthalate (DUP), ditridecyl phthalate (DTDP), butylbenzyl phthalate (BBP), alkylbenzyl phthalate, Santicizer® 261); - ricinoleic acid derivatives (methyl ricinoleate, n-butyl acetylricinoleate, castor oil); Sebacic acid derivatives (di-2-ethylhexyl sebacate (DOS)); stearic acid derivatives (n-butyl stearate); - sucrose derivatives (sucrose acetate isobutyrate (SAIB)); sulfonic acid derivatives ((o,p)-toluenesulfonamide, N-ethyl-(o,p)-toluenesulfonamide, phenol alkylsulfonates and creosol (Mezamol®)); - terephthalic acid derivatives (bis(2-ethylhexyl) terephthalate (DOTP); Trimellitic acid derivatives (tris(2-ethylhexyl) trimellitate (TO™), heptylnonyl trimellitate (79™), triisononyl trimellitate (TIN™)); polyesters such as adipic polyester (mol wt 6000), Paraplex® G-40, adipic polyester (mol wt 2000), Santiclzer® 334F, azelaic polyester (mol wt 2200), Platolein (copyright) 9720, sebacic polyester (mol wt 8000), Paraplex® G-25); and Manufacture process according to claim 1, characterized in that it can be selected from the group consisting of terpenes and derivatives (camphor, hydrogenated rosin methyl ester).

8. 8. A manufacturing process according to claim 7, characterized in that dibutyl phthalate is preferably used.

9. 9. The manufacturing process of claim 8, wherein the glue is applied using a Bird-type extender.

10. A repair adhesive obtainable by the process of any one of claims 1 to 9, characterized in that it is ductile and flexible, has low permeability to water and gases, exhibits chemical resistance and thermal stability up to 150°C.

11. 11. The repair adhesive of claim 10, characterized in that it is waterproof and provides effective thermal insulation.

12. 12. A repair adhesive according to claim 11 or 11, characterized in that it has a durability of at least 2 years.

13. 13. Use of the repair adhesive according to any one of claims 10 to 12, characterized in that it is used as an anti-corrosion repair agent to be applied to any metal surface, whether painted or not, in land and marine areas.

14. 14. Use according to claim 13, characterized in that the application is carried out in liquid form as a spray or in solid form in the form of an adhesive tape.

15. 15. Use according to claim 14, characterized in that when applied in liquid form, a solution of dissolved thermoplastic material, preferably PET, is deposited on the metal surface by spraying or with a brush to form a polymer film after 5 minutes.

16. 16. Use according to claim 15, characterized in that the solution consists of the direct application of a solution composed of a thermoplastic material dissolved in a strong carboxylic acid and an organic solvent.

17. 17. The use according to claim 16, characterized in that the solution preferably has the following composition: 20% (w / w) PET, 50% (v / v) TFA and 50% (v / v) DCM.

18. Use according to any one of claims 15 to 17, characterized in that it further comprises the use of said solution as a gel that can be applied to said surface using a brush.

19. Use according to claim 14, characterized in that the application in solid form consists of producing the adhesive according to the process according to any one of claims 1 to 9, applying the adhesive directly to a metal substrate and adding a layer of the glue and a silicone paper liner to protect the adhesive.

20. 14. Use according to claim 13, characterized in that the adhesive can be removed manually or by abrasive blasting.

21. 21. Use according to claim 20, characterized in that the abrasive blasting can be, for example, hydroblasting or metal oxide blasting.

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