Method for treating auxiliary members used in the manufacture of parts containing epoxy polymers

Abstract

1. A method for treating an auxiliary member used in the manufacture of an epoxy polymer-containing product, comprising: providing an auxiliary member used in the manufacture of an epoxy polymer, wherein the auxiliary member is contaminated with contaminants comprising uncured, partially cured, and / or fully cured epoxy polymer; exposing the contaminated auxiliary member to a stripping agent to strip the contaminants from the auxiliary member and form a contaminated by-product comprising the stripping agent and the contaminants; and separating the auxiliary member from the contaminated by-products; wherein the epoxy polymer is an acid-decomposable epoxy polymer and the stripping agent comprises an acid.

Description

[Technical Field]

[0001] The present disclosure relates to a method for treating a support member used in the manufacture of a part comprising an epoxy polymer. [Background technology]

[0002] Composite structures such as wind turbine blades are typically manufactured using epoxy resin impregnation techniques, where a vacuum draws liquid resin into a pre-formed arrangement of reinforcement material, allowing the resin to harden and form a solid part.

[0003] Various auxiliary parts, such as vacuum bags, resin tubing, and distribution media, are required to facilitate the handling of resin, but these are currently treated as non-recyclable waste, discarded after a single impregnation process, mainly due to the difficulty of removing epoxy resins, which have different degrees of cure, from the auxiliary parts.

[0004] Additionally, even reusable components such as molds and tools may be discarded if they become excessively contaminated with epoxy resin.

[0005] Although many of the auxiliary components are composed of materials for which there are established methods for recycling, there is currently no established means for reusing or recycling them after they become contaminated with cured, partially cured, or uncured resin during the impregnation process.

[0006] The present invention was devised based on this background. [Brief explanation of the drawings]

[0007] [Figure 1] (a) to (c) are schematic diagrams of a typical resin impregnation device, where (a) shows the device before resin impregnation, (b) shows the device during resin impregnation, and (c) shows the device after resin impregnation is complete. [Figure 2]FIG. 1 is a flowchart illustrating a method for treating an auxiliary member according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] In one aspect, the present invention provides a method for treating a sub-member used in the production of an epoxy polymer.

[0009] The method of the present invention includes providing a support member for use in the manufacture of an epoxy polymer-containing product, the support member being contaminated with a contaminant.

[0010] The contaminants include uncured, partially cured, and / or fully cured epoxy polymers. In other words, the contaminants may include epoxy polymers, which may be in the form of a cured epoxy polymer resin matrix, oligomers, which may be in the form of a partially cured epoxy polymer resin component, and monomers, which may be in the form of an uncured epoxy polymer liquid resin.

[0011] In some embodiments, the contaminants include partially cured and uncured epoxy resins, hi some embodiments, the contaminants include fully cured epoxy polymers.

[0012] The method further includes exposing the contaminated back-up member to a release agent to dislodge the contaminants from the back-up member and form a contaminant by-product comprising the release agent and the contaminants, which at this stage may be in the form of swollen epoxy particles or dissolved or suspended epoxy monomers or oligomers.

[0013] Preferably, the contaminant by-products include swollen epoxy particles that can be separated from the contaminant by-products, for example by filtration, and recycled by depolymerization or reused as filler.

[0014] Finally, the method includes separating the auxiliary member from the contaminating by-products.

[0015] The epoxy polymer is an acid-decomposable epoxy polymer, and the release agent contains an acid. Here, "acid-decomposable epoxy polymer" refers to an epoxy polymer that, upon exposure to an acid-containing release agent, has the ability to swell and mechanically cleave some of its chemical bonds to form swollen epoxy polymer particles, or that can be chemically decomposed and depolymerized into monomers and / or oligomers.

[0016] The process by which an acid-decomposable epoxy polymer swells to form swollen epoxy polymer particles is referred to herein as "swelling," "acid breaking," and "disintegrating," which are used interchangeably.

[0017] Examples of acid-decomposable epoxy polymers include those based on amine-cured epoxy resins, such as Olin Airstone 760, Hexion RIMR 035C impregnating epoxy, and Aditya Birla Recyclamine system. In other words, epoxy polymers based on amine-cured epoxy resins belong to a subgroup of acid-decomposable epoxy polymers. In the method of the present invention, it is preferred that the uncured, partially cured, or fully cured epoxy polymer contained in the contaminant be based on an amine-cured epoxy resin.

[0018] By removing contaminants from the auxiliary component and separating it from the contaminating by-products, a cleaner component is obtained that can be reused or recycled.

[0019] In other words, one aspect of the present invention relates to a method for recycling auxiliary components used in the manufacture of epoxy polymer-containing products that have become contaminated with uncured, partially cured, and / or fully cured epoxy polymers. In particular, it has been determined that consumables made of or consisting solely of thermoplastic polymers, such as vacuum bags, tubing, valves, etc., used in the manufacture of epoxy polymer-containing products, can be more easily recycled, for example, by remelting and remolding, if the epoxy polymer contaminants are removed.

[0020] In some embodiments, contaminants can be extracted from the contaminated by-products and then reused or recycled. Extraction can include, for example, adjusting the pH of the contaminated by-products, filtering, drying by oven or spray drying, followed by filtration of the swollen epoxy particles or separation by cyclone separator. Extraction can also include distillation, preferably under reduced pressure. Extraction can also include separation of the contaminated by-products by cooling, optionally combined with filtration.

[0021] In this way, it is possible to reduce waste generated in the manufacture of epoxy polymer-containing parts, such as wind turbine blades. The chemically degraded epoxy polymer monomers and / or oligomers can be physically separated from the contaminating by-products by phase separation, distillation, or chemical means.

[0022] Recycling of the contaminated material may include depolymerizing the contaminated material back to its monomer, preferably bisphenol A (BPA), if the contaminated material is a partially or fully cured epoxy polymer resin. Because BPA has no natural source and is produced from fossil-derived raw materials, it is highly desirable to recycle and recover BPA from epoxy polymers that would otherwise end up in landfills for mixing with auxiliary components.

[0023] The release agent can be recovered during the process, for example, as a filtered fraction or by spray drying and gas condensation after solid separation. The release agent, together with any remaining small amounts of contaminants, can then be reused as a release agent after treatment (e.g., purification or composition adjustment) or recycled. If recycled, it is preferable to extract all (not just a portion) of the contaminants from the contaminated by-products before reusing the release agent.

[0024] The method may include extracting at least some of the contaminants from the contaminated by-product and then recycling the contaminated by-product as a release agent, which may be further processed, for example by purification or composition adjustment, before being recycled as a release agent.

[0025] Contaminants may include inert components that may migrate from the support component into the contaminant by-products, such as non-swelling polymeric components (e.g., acid-resistant epoxies, thermoplastic polymers, polyesters), metal components (e.g., sensors, lightning conductors, lightning receptors, fasteners), fibrous components (e.g., glass fibers, carbon fibers, or composites of such fibers with an inert matrix material), or particulate components (e.g., ceramic, glass, inert polymer particles).

[0026] Surprisingly, it has been found that release of contaminants is particularly rapid when the release agent contains an organic acid, in particular formic acid and / or acetic acid. In particular, it has been confirmed that release agents containing formic acid achieve rapid release when the acid concentration is high, for example, an aqueous solution containing more than 50% by weight of formic acid, preferably 60 to 100% by weight, and more preferably 75 to 95% by weight of formic acid.

[0027] The step of exposing the contaminated support member to a release agent may include spraying, dipping, and / or rinsing with the release agent.

[0028] To increase the rate of release of contaminants from the support member, the release agent may be heated before or during exposure to the support member. For example, the release agent may be heated to 25° C. or higher, 40° C. or higher, or (most preferably) 50° C. or higher to allow for more rapid release. However, it has been found that temperatures that are too high are undesirable because they can cause degradation of the support member, excessive evaporation of the release agent, and / or excessive energy consumption.

[0029] Therefore, the release agent is preferably heated to less than 90°C, and more preferably less than 80°C. The release agent may be heated in a container equipped with an internal or external heating device before being sprayed onto the auxiliary member. Alternatively, the release agent may be heated in a container into which the auxiliary member containing the contaminant is immersed. Furthermore, the auxiliary member and the release agent may be placed or transported together in an oven, and the release agent may be heated after exposure.

[0030] The method may include subjecting the contaminated back-up member to a mechanical treatment before, during, or after exposing the member to the release agent, which may include, for example, crushing the contaminated material into small pieces, peeling the contaminant material from the surface of the back-up member, or breaking the contaminated back-up member itself into small pieces.

[0031] In some cases, mechanical treatment can improve contact between the contaminant and the release agent, promoting a more effective or faster reaction, and can also be effective in achieving faster and more complete separation of the support component from the contaminant by-products.

[0032] In some cases, mechanical treatment can remove some of the contaminants from the contaminated support member before exposing it to the release agent, thereby, for example, shortening the exposure time of the release agent to the contaminated support member or reducing the amount of contaminants that must be separated from the contaminant by-products before the release agent can be reused.

[0033] Mechanical treatment may include, for example, impacting, bending, compressing, cutting, scraping, brushing, (high) pressure cleaning with air or water, vacuum cleaning, scrubbing, shaking, and / or washing, which may include or be followed by a treatment to separate the mechanically removed contaminants from the contaminated supporting member.

[0034] The method may also include subjecting the contaminated back-up member to mechanical treatment during or after exposure to the release agent, which has been found to be useful in increasing the rate of contaminant release and reducing the amount of contaminant remaining on the back-up member after treatment. Specific treatments include brushing, (high) pressure washing with air or water, vacuum cleaning, scrubbing, shaking, and the like.

[0035] Theoretically, the effect of the mechanical treatment is thought to occur by, but not limited to, facilitating access to the interior of the contaminants, particularly during the demolding process, facilitating the removal of swollen epoxy particles loosely bound to the support member after the demolding process, or physically breaking down the contaminants into small pieces and peeling them off the surface of the support member.

[0036] The auxiliary components may include thermoplastic materials or may include secondary materials and consumables used in the manufacture of composite wind turbine blades, such as vacuum bags, resin distribution media, hoses and tubes, valves, spatulas, buckets, brushes, rollers, molds, etc.

[0037] The auxiliary member may include a confined space, which may be contaminated with a contaminant. As used herein, "confined space" means a space with limited or difficult access. Thus, examples of confined spaces in this context include structures with open or blind holes, such as tubes, hoses, pipes, buckets, cups, and other partially closed containers.

[0038] In such cases, the method may further include mechanically removing at least some of the contaminants from the enclosed space before or during exposure of the contaminated support member to the release agent. Mechanical removal can be accomplished by, for example, drilling, scraping, pushing (e.g., with pressurized air, water, solvents, and / or release agents), pulling (e.g., with a vacuum or a tool having a hook-like structure), crushing (e.g., by impact, bending, or compression), and / or peeling off the support member or contaminants.

[0039] Preferably, the mechanical removal is carried out when the contaminant is in an uncured or partially cured state and has some degree of fluidity, because this facilitates removal by non-contact means such as vacuum or compressed air and reduces secondary contamination of other auxiliary members.

[0040] The mechanically removed contaminants may be combined with the contaminant by-products, where they may be swollen and / or chemically degraded and recycled along with the swollen epoxy particles or chemically degraded epoxy polymer.

[0041] Mechanical removal of at least a portion of the contaminant from the enclosed space allows the release agent to swell or chemically decompose into the contaminant, shortening the distance it must travel, and consequently reducing the release time of the contaminant.

[0042] The auxiliary components can be used in the manufacture of a variety of products that contain acid-degradable epoxy polymers, including products with acid-degradable epoxy polymer-based coatings, electrical and electronic systems, adhesives, and fiberglass reinforced products (such as boats, kayaks, swimming pools, and composite parts).

[0043] In particular, the method of the present invention has proven extremely useful when the auxiliary component is used in the manufacture of wind turbine blades, due to the large size of wind turbine blades and the large amount of consumables, such as vacuum bags, used in their manufacture.

[0044] In each of the above methods, the release agent may further contain an organic solvent, a surfactant, a colorant and / or a salt.

[0045] In order that the invention may be more clearly understood, reference will now be made by way of example only to the drawings in which like reference numerals refer to similar elements and in which:

[0046] Generally, embodiments of the present invention provide a method for treating a support component that has come into contact with a liquid epoxy polymer resin system during the manufacture of an epoxy polymer-containing product (e.g., a composite, more preferably a wind turbine blade) and that has become contaminated with uncured, partially cured, and / or fully cured epoxy polymer.

[0047] The method involves exposing the contaminated support member to an acid-containing release agent to remove the resin system from the surface of the member. The release agent reacts with the resin system, causing it to swell or chemically decompose, thereby releasing the resin system from the surface of the member. The support member, from which the resin system has been removed, is left clean and can be reused or recycled as raw materials.

[0048] For purposes of understanding the background of the present invention, Figures 1(a)-(c) show a schematic example of a typical resin impregnation process that may be used to manufacture all or part of a composite wind turbine blade.

[0049] As shown, a stiffener assembly 2 is placed within a mold cavity 4 and covered with a vacuum bag material 6. In this example, the stiffener assembly 2 includes multiple layers of fiber reinforcement 8, such as fiberglass, carbon, and / or aramid fibers. However, it is contemplated that the stiffener assembly 2 may include any type and combination of reinforcement suitable for manufacturing wind turbine blades. Specific examples include foam or balsa cores, composite structures such as spar caps, sensors, lightning conductors and receptors, heating panels, root inserts, and the like.

[0050] The vacuum bag material 6 is tightly sealed to the top surface 10 of the mold cavity 4, forming an airtight space 24 between the vacuum bag material 6 and the top surface 10 of the mold cavity 4 around the stiffener assembly 2. An outlet line 12 connected to a vacuum pump (not shown) is connected to the outlet valve of the vacuum bag material 6, and an inlet line 18 from a reservoir 20 storing a liquid resin 26 of an acid-decomposable epoxy polymer is connected to the vacuum bag material 6 through the inlet valve.

[0051] During the resin impregnation process, air is evacuated from the airtight space 24 through the exhaust valve, creating a vacuum around the stiffener assembly 2. This causes the liquid resin 26 to be drawn into the stiffener assembly 2 through the inlet valve by the vacuum. In some embodiments, a resin distribution medium (or flow media) is placed between the top surface of the stiffener assembly 2 and the vacuum bag 6 to promote uniform resin flow throughout the stiffener assembly 2.

[0052] Such distribution media is typically constructed of high density polyethylene mesh. After the stiffener assembly 2 is fully wetted with the liquid resin 26, the resin hardens to form a matrix material that bonds the stiffener assembly into a unitary rigid part.

[0053] Generally, liquid resin 26 is a highly viscous liquid prepolymer system designed to be converted to a solid polymer system through a curing process. Liquid resin (or resin system) 26 includes a base resin component and may also include a hardener or accelerator that chemically induces the curing reaction. The curing of resin system 26 may also be accelerated by the application of heat or ultraviolet (UV) light.

[0054] The epoxy polymer matrix material obtained by curing the liquid resin 26 is a thermoset material. As is well known, a thermoset material is a solid polymer system obtained by irreversible chemical crosslinking of the resin system. Due to the nature of these irreversible chemical crosslinks, known thermoset materials are not easily chemically degraded, making recycling difficult.

[0055] The epoxy polymer resin systems used in the manufacture of the epoxy polymer-containing products discussed herein are acid-degradable epoxy polymers. Examples of acid-degradable epoxy polymers include those based on amine-cured epoxy resins, such as Olin Airstone 760, Hexion RIMR 035C impregnating epoxy, and Aditya Birla Recyclamine systems.

[0056] Materials and components used during the resin impregnation process that do not become part of the cured part, such as the vacuum bag material 6, inlet and outlet valves, inlet and outlet lines 12, 18, distribution media, and others, are known as auxiliary parts or materials. These include disposable or single-use consumables. Examples of such materials include the vacuum bag material 6, inlet and outlet lines 12, 18, and distribution media, which are typically constructed from thermoplastic materials. Examples of thermoplastic materials include polyethylene, polypropylene, polystyrene, nylon, and PET (polyethylene terephthalate). Valves may be constructed from thermoplastic and / or metal materials. Other auxiliary parts include tooling and dies intended for multiple uses.

[0057] Tools used in other manufacturing processes for handling and applying epoxy resins are also considered auxiliary parts and can be treated by the method of the present invention. Examples include spatulas, brushes, rollers, and buckets. Another category of auxiliary parts is personal protective equipment. Handling epoxy resins may require the use of protective gear such as protective clothing, gloves, safety glasses, and safety shoes. If these auxiliary parts become contaminated by resin during use, they are typically discarded. However, removing the contaminants using the method of the present invention may increase their reusability and potentially improve their value as recycled materials.

[0058] The liquid resin 26 contacts these auxiliary components during the resin preparation and / or impregnation process, and due to the viscosity and adhesiveness of the resin, some of it adheres to the surfaces of the auxiliary components. As the impregnation process progresses, this adhered resin may partially or fully cure on the auxiliary components, resulting in the auxiliary components being contaminated with uncured, partially cured, and / or fully cured epoxy polymer resin. That is, the auxiliary components are contaminated with liquid prepolymer resin and / or solid epoxy polymer matrix material.

[0059] A method for treating such contaminated support components is shown in flow chart form in Figure 2. As shown, the first step 28 of the method involves recovering the contaminated support components from the resin impregnation apparatus after the resin impregnation process is complete. The support components may be contaminated because they are fully cured, uncured, partially cured, or a combination thereof.

[0060] Optionally (if necessary), the contaminated auxiliary components may be mechanically disassembled by cutting or crushing before being disposed of.

[0061] In the next step 30, the contaminated auxiliary member is exposed to a release agent, for example, a release agent containing an acid such as acetic acid or formic acid, which causes the uncured, partially cured, or fully cured epoxy resin to swell into swollen epoxy particles or to chemically decompose into monomers and / or oligomers, which are then released from the auxiliary member.

[0062] In this case, the acetic acid or formic acid in the release agent is preferably present at a concentration of 60 to 90% in water, more preferably 75 to 95%. The release agent softens, disintegrates, or dissolves the resin, causing it to separate from the surface of the auxiliary member. That is, the resin separates from the surface of the auxiliary member and forms contaminating by-products together with the release agent and, if necessary, inert components such as glass fibers.

[0063] The rinsing treatment in step 30 may be performed by, for example, immersing the contaminated auxiliary member in a bath of release agent. To ensure sufficient reaction time, the immersion is preferably performed for up to about one hour. However, depending on the temperature, the concentration of the release agent, the surface area / volume ratio of the contaminants, and other factors, the immersion time may be extended to 10 hours or even 48 hours. Mechanical treatment can also be used to further shorten the release time.

[0064] The contaminant by-products, consisting of release agent and decomposed resin, collect in the bath and are present as a mixture or solution of acid and decomposed resin. Additionally or alternatively, the contaminant by-products may include solid resin pieces or swollen epoxy polymer particles, which may settle to the bottom of the bath.

[0065] When the auxiliary member is a hose or a tube (for example, an inlet line or an outlet line), the release of the resin is further promoted by passing the release agent through the hose.

[0066] As shown in step 32, the release agent may be heated before or during the rinsing process of the auxiliary member, which has been shown to improve the speed of contaminant removal. The use of a heated release agent is particularly advantageous when the auxiliary member is made of a thermoplastic material. In such cases, the increased temperature of the release agent increases the flexibility of the auxiliary member, making mechanical removal easier. The release agent is preferably heated to approximately 60°C to 90°C.

[0067] After the resin has been released from the support component, the support component is removed from the release agent or contaminating by-product bath and prepared for recycling or reuse (steps 34 and 36). For example, the support component can be rinsed with water to remove any residual contaminating by-products, and then dried, such as with pressurized gas, so that it can be reused in a subsequent resin impregnation process. Alternatively, the cleaned support component can be fed into an appropriate waste treatment stream as a higher value, more easily recyclable raw material.

[0068] In step 38, after the auxiliary components have been removed from the contaminated by-products, the contaminants, including the decomposed resins, are extracted using one or more suitable separation techniques, such as pH adjustment, filtration, centrifugation, evaporation, spray drying, cyclone separators, etc.

[0069] In step 40, the recovered decomposed resin is recycled using known recycling techniques, which may include, for example, depolymerization to obtain BPA (bisphenol A), which can be used as a green source for new epoxy resins.

[0070] After the contaminants, including the decomposed resins, have been at least partially extracted from the contaminated by-products, the release agent is treated as necessary and reused in the contaminated auxiliary member treatment method of the present invention (step 42).

[0071] Reusing the release agent is particularly advantageous when only a portion of the contaminants have been extracted, since reusing the release agent allows the unextracted contaminants to eventually be extracted during a later use.

[0072] Furthermore, a process that extracts only a portion of the contaminants is faster and more energy efficient, i.e., it corresponds to extracting at least some of the contaminants from the contaminated by-products before reusing the contaminated by-products as release agents.

[0073] It is also contemplated that multiple auxiliary members may be rinsed simultaneously in the same bath.

[0074] Those skilled in the art will appreciate that various modifications could be made to the specific embodiments illustrated above without departing from the scope of the inventive concept as defined in the claims.

Claims

1. 1. A method for treating a support member used in the manufacture of a product comprising an epoxy polymer, comprising: providing a support member for use in the manufacture of an epoxy polymer, wherein the support member is contaminated with contaminants including uncured, partially cured, and / or fully cured epoxy polymer; exposing the contaminated back-up member to a stripping agent to strip the contaminants from the back-up member and form a contaminant by-product comprising the stripping agent and the contaminants; and separating the auxiliary member from the contaminating by-products. A method comprising: The method, wherein the epoxy polymer is an acid-decomposable epoxy polymer and the stripping agent comprises an acid.

2. 2. The method of claim 1, wherein the stripping agent comprises an organic acid, preferably formic acid and / or acetic acid.

3. 3. The method of claim 1 or 2, wherein the contamination by-products comprise swollen epoxy particles.

4. 10. The method of any preceding claim, wherein the epoxy polymer is based on an amine-cured epoxy resin.

5. 10. A method according to any preceding claim, further comprising the step of recycling or reusing the auxiliary member.

6. 10. A method according to any preceding claim, further comprising the step of extracting said contaminants from said contaminated by-products and recycling said contaminants, preferably said recycling comprising depolymerisation of said contaminants.

7. 10. The method of any preceding claim, further comprising the step of reusing the contaminated by-products as a stripping agent after extracting at least a portion of the contaminants from the contaminated by-products.

8. 10. The method of any preceding claim, wherein the contaminant comprises an inert component that migrates from the auxiliary component to the contaminant by-product, preferably the inert component being a non-swelling polymer component, a metal component, a fibrous component or a particulate component.

9. 10. The method according to any preceding claim, wherein the stripping agent further comprises an organic solvent, a surfactant, a colorant and / or a salt.

10. 10. The method of claim 1, wherein the contaminant comprises an uncured and / or partially cured epoxy polymer, further comprising the step of curing the epoxy polymer before exposing the support member to the release agent.

11. 10. The method according to any preceding claim, wherein the step of exposing the support member to the stripping agent comprises spraying, dipping and / or rinsing with the stripping agent.

12. 10. The method of any preceding claim, further comprising the step of heating the release agent before or during exposure of the backing member to the release agent.

13. 10. The method of any preceding claim, further comprising the step of mechanically treating the contaminated support member.

14. 10. The method of any preceding claim, further comprising the step of mechanically treating the contaminated back-up member during and / or after exposure to the stripping agent.

15. 10. A method according to any preceding claim, wherein the auxiliary member comprises a thermoplastic polymer.

16. 10. A method according to any preceding claim, wherein the auxiliary members comprise one or more of a vacuum bag, a tube or hose, a valve, a tool, a protective gear and / or a mould.

17. 10. The method according to claim 1, wherein the auxiliary member has an enclosed space and the enclosed space is contaminated with the contaminant, further comprising the step of mechanically removing at least a portion of the contaminant from the enclosed space before or during exposure to the stripping agent.

18. 10. A method according to any preceding claim, wherein the auxiliary part is an auxiliary part used in the manufacture of wind turbine blades.

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