Compositions and methods for cleaning and stripping

Abstract

This invention relates to compositions and methods for cleaning and peeling. This disclosure provides a composition for cleaning or peeling materials from a substrate. The composition includes a primary solvent and a co-solvent. The co-solvent includes one or more caprolactam-derived solvents.

Description

[0001] This application is a divisional application of parent application number 201980023732.3. The parent application was filed on March 27, 2019; the invention is entitled "Composition and Method for Cleaning and Peeling".

[0002] Cross-reference to related applications This application claims the benefit of U.S. Provisional Patent Application Serial No. 62 / 650,363, entitled “COMPOSITIONS AND METHODS FORCLEANING AND STRIPPING”, filed on March 30, 2018, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to compositions and methods for cleaning materials from a substrate. In particular, this disclosure relates to compositions and methods for cleaning or stripping paints, inks, and resins from a substrate. Background Technology

[0004] Cleaning compositions are widely used to remove paint, ink, and polymer resins from a variety of substrates. For example, cleaning compositions are used to peel cured paint from substrates, clean wet or partially cured paint from painting equipment, clean ink from rollers in offset printing, and clean polymer resins from polymer resin processing equipment.

[0005] In some cases, the solvents mentioned include N-methyl-2-pyrrolidone (NMP). NMP is an excellent solvent for many of the most difficult-to-dissolve materials. However, NMP has been identified as a reproductive toxin. Based on the EPA's assessment of potential human hazards, the acute and chronic risks identified for individuals using NMP for less than four hours per day can be reduced by using appropriate chemical-resistant gloves. However, gloves and respirators do not adequately reduce the risk for individuals using NMP for more than four hours per day or repeated use of NMP over several consecutive days. There is a need for a solvent that dissolves paints, inks, and resins that is neither a reproductive toxin nor a suspected carcinogen or mutagen. Summary of the Invention

[0006] This disclosure provides a composition for cleaning or stripping materials from a substrate. The composition includes a primary solvent and a co-solvent. The co-solvent includes one or more caprolactam-derived solvents according to the following general formula: , Where R is a linear alkyl group with 1, 2, or 4 unsubstituted carbons.

[0007] In one form, this disclosure provides a composition comprising a primary solvent and a co-solvent. The co-solvent includes one or more caprolactam-derived solvents. Caprolactam-derived solvents are defined according to the following general formula: , Where R is a linear alkyl group with 1, 2, or 4 unsubstituted carbons.

[0008] The concentration of the co-solvent in the composition may be 5% to 49% by weight of the composition. One or more caprolactam-derived solvents in the composition may include at least one of the following: N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam. One or more caprolactam-derived solvents in the composition may include two caprolactam-derived solvents. Each of the two caprolactam-derived solvents in the composition may be 5% to 95% by weight of the co-solvent. The two caprolactam-derived solvents in the composition may be N-methylcaprolactam and N-ethylcaprolactam. Alternatively, the two caprolactam-derived solvents in the composition may be N-methylcaprolactam and N-butylcaprolactam. Alternatively, the two caprolactam-derived solvents in the composition may be N-ethylcaprolactam and N-butylcaprolactam.

[0009] The caprolactam-derived solvent in the composition may further include a third caprolactam-derived solvent. Each of the three caprolactam-derived solvents in the composition may be 5 wt% - 90 wt% of a cosolvent. The three caprolactam-derived solvents in the composition may be N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam. The composition may further contain a surfactant. The composition may further contain a thickener.

[0010] In another form, this disclosure provides a method for cleaning materials from a substrate. The method includes applying a composition to the substrate for a period of time to dissolve at least some of the material, and then removing the composition comprising the dissolved material from the substrate. The composition includes a primary solvent and a co-solvent. The co-solvent includes one or more caprolactam-derived solvents according to the following general formula: , Where R is a linear alkyl group with 1, 2, or 4 unsubstituted carbons.

[0011] The one or more caprolactam-derived solvents used in this method may include at least one of the following: N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam. The one or more caprolactam-derived solvents used in this method may include at least two of the following: N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam. The composition of the method may further include at least one of the following: a surfactant and a thickener. The materials used in this method may include paints, inks, and / or polymer resins.

[0012] The above and other features of the invention, as well as the ways in which they are implemented, will become more apparent from the following description, and the invention itself will be better understood. Detailed Implementation

[0013] This disclosure provides compositions for cleaning or stripping materials from a substrate, wherein a caprolactam-derived solvent replaces NMP in the composition. The base of the caprolactam-derived solvent, caprolactam, has not been discovered and is not expected to be a reproductive toxin or carcinogen. In particular, N-methylcaprolactam is not considered a reproductive toxin or carcinogen. Therefore, caprolactam-derived solvents, such as N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam, are significantly safer solvents than NMP. It has been surprisingly found that caprolactam-derived solvents are as effective as NMP in dissolving many materials.

[0014] This disclosure provides a composition comprising a primary solvent and a co-solvent. The co-solvent may include one or more caprolactam-derived solvents. Caprolactam-derived solvents may be formulated according to the following general formula: Formula I , Where R is a linear alkyl group with 1, 2, or 4 unsubstituted carbons. For example, if R is methyl (-CH3), the solvent for caprolactam derivatization is N-methylcaprolactam according to formula II: Formula II: .

[0015] If R is ethyl (-CH2CH3), then the solvent for caprolactam derivatization is N-ethylcaprolactam according to formula III: Formula III: .

[0016] If R is butyl (-CH2CH2CH2CH3), then the solvent for caprolactam derivatization is N-butylcaprolactam according to formula IV: Formula IV: .

[0017] The co-solvent may include N-methylcaprolactam, N-ethylcaprolactam, and / or N-butylcaprolactam. The co-solvent may consist of any of the caprolactam-derived solvents described above.

[0018] The co-solvent may include two caprolactam-derived solvents. For example, the co-solvent may include N-methylcaprolactam and N-ethylcaprolactam. Alternatively, the co-solvent may include N-methylcaprolactam and N-butylcaprolactam. Alternatively, the co-solvent may include N-ethylcaprolactam and N-butylcaprolactam. The co-solvent may consist of two of the above-mentioned caprolactam-derived solvents.

[0019] In a composition in which the cosolvent comprises two caprolactam-derived solvents, each of the caprolactam-derived solvents may be as little as 5% (wt%), 6% (wt%), 8% (wt%), 10% (wt%), 15% (wt%), 20% (wt%), 25% (wt%), 30% (wt%), 33% (wt%), 35% (wt%), 40% (wt%), 45% (wt%), or 49% (wt%) of the total weight of the cosolvents, or as much as 51% (wt%), 55% (wt%), 60% (wt%), 65% (wt%), 67% (wt%), 70% (wt%), 75% (wt%), 80% (wt%), 85% (wt%), or 90% (wt%) of the total weight of the cosolvents. The weight percentage, 92 wt%, 94 wt%, or 95 wt%, or any range that may be defined between any two of the above values, for example, 5 wt% to 95 wt%, 6 wt% to 94 wt%, 8 wt% to 92 wt%, 10 wt% to 90 wt%, 15 wt% to 85 wt%, 20 wt% to 80 wt%, 25 wt% to 75 wt%, 30 wt% to 70 wt%, 33 wt% to 67 wt%, 35 wt% to 65 wt%, 40 wt% to 60 wt%, 45 wt% to 55 wt%, or 49 wt% to 51 wt%.

[0020] In compositions in which the cosolvent comprises N-methylcaprolactam and N-ethylcaprolactam, each of the caprolactam-derived solvents may be as little as 5% (wt%), 6%, 8%, 10%, 15%, 20%, 25%, 30%, 33%, 35%, 40%, 45%, or 49% (wt%) of the total weight of the cosolvent, or as much as 51%, 55%, 60%, 65%, 67%, 70%, 75%, 80%, or 85% (wt%) of the total weight of the cosolvent. 90 wt%, 92 wt%, 94 wt%, or 95 wt%, or any range that may be defined between any two of the above values, for example, 5 wt% to 95 wt%, 6 wt% to 94 wt%, 8 wt% to 92 wt%, 10 wt% to 90 wt%, 15 wt% to 85 wt%, 20 wt% to 80 wt%, 25 wt% to 75 wt%, 30 wt% to 70 wt%, 33 wt% to 67 wt%, 35 wt% to 65 wt%, 40 wt% to 60 wt%, 45 wt% to 55 wt%, or 49 wt% to 51 wt%.

[0021] In compositions in which the cosolvent comprises N-methylcaprolactam and N-butylcaprolactam, each of the caprolactam-derived solvents may be as little as 5% (wt%), 6%, 8%, 10%, 15%, 20%, 25%, 30%, 33%, 35%, 40%, 45%, or 49% (wt%) of the total weight of the cosolvent, or as much as 51%, 55%, 60%, 65%, 67%, 70%, 75%, 80%, or 85% (wt%) of the total weight of the cosolvent. 90 wt%, 92 wt%, 94 wt%, or 95 wt%, or any range that may be defined between any two of the above values, for example, 5 wt% to 95 wt%, 6 wt% to 94 wt%, 8 wt% to 92 wt%, 10 wt% to 90 wt%, 15 wt% to 85 wt%, 20 wt% to 80 wt%, 25 wt% to 75 wt%, 30 wt% to 70 wt%, 33 wt% to 67 wt%, 35 wt% to 65 wt%, 40 wt% to 60 wt%, 45 wt% to 55 wt%, or 49 wt% to 51 wt%.

[0022] In compositions in which the cosolvent comprises N-ethylcaprolactam and N-butylcaprolactam, each of the caprolactam-derived solvents may be as little as 5% (wt%), 6%, 8%, 10%, 15%, 20%, 25%, 30%, 33%, 35%, 40%, 45%, or 49% (wt%) of the total weight of the cosolvent, or as much as 51%, 55%, 60%, 65%, 67%, 70%, 75%, 80%, or 85% (wt%) of the total weight of the cosolvent. 90 wt%, 92 wt%, 94 wt%, or 95 wt%, or any range that may be defined between any two of the above values, for example, 5 wt% to 95 wt%, 6 wt% to 94 wt%, 8 wt% to 92 wt%, 10 wt% to 90 wt%, 15 wt% to 85 wt%, 20 wt% to 80 wt%, 25 wt% to 75 wt%, 30 wt% to 70 wt%, 33 wt% to 67 wt%, 35 wt% to 65 wt%, 40 wt% to 60 wt%, 45 wt% to 55 wt%, or 49 wt% to 51 wt%.

[0023] The cosolvent may include three caprolactam-derived solvents. In compositions in which the cosolvent includes three caprolactam-derived solvents, the cosolvent may include N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam. The cosolvent may consist of three caprolactam-derived solvents as described above.

[0024] In a composition in which the cosolvent comprises three caprolactam-derived solvents, for example, each of the caprolactam-derived solvents may be as little as 5 wt%, 6 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 33 wt%, 35 wt%, 40 wt%, 45 wt%, or 49 wt%, or as much as 50 wt%, 55 wt%, 60 wt%, 65 wt%, 67 wt%, 70 wt%, 75 wt%, 80 wt%, 84 wt%, 88 wt%, or 90 wt%, or in any range defined between any two of the above values, for example, 5 wt% to 90 wt%, 1 wt% to 88 wt%, 8 wt% to 84 wt%, 10 wt% to 80 wt%, 15 wt% to 70 wt%, 20 wt% to 60 wt%, or 25 wt% to 50 wt%.

[0025] The primary solvent may include aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, water, or any combination thereof. These solvents may be cheaper than caprolactam-derived solvents, thus reducing the overall cost of the composition. Primary solvents may include alkyl lactates, esters such as butyl propionate, lactones such as γ-butyrolactone, dioxolane, glycols, glycol ethers, glycol ether acetates, ether esters such as ethyl 3-ethoxypropionate, dialkyl carbonates, alkylene carbonates, alkoxy alcohols and diesters such as dimethyl adipic acid, glutaric acid and succinic acid, ketones such as cyclohexanone, water, or any combination thereof.

[0026] The concentration of the cosolvent in the composition may be as little as 5 wt%, 6 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, or as much as 30 wt%, 33 wt%, 35 wt%, 40 wt%, 45 wt%, or 49 wt% of the total weight of the composition, or may be in any range between any two of the above values, for example, 5 wt% to 49 wt%, 6 wt% to 45 wt%, 8 wt% to 40 wt%, 10 wt% to 35 wt%, 20 wt% to 30 wt%, or 25 wt% to 33 wt%.

[0027] Cleaning materials from a substrate may involve contacting the material on the substrate with any of the compositions described above for a period of time, and then removing the composition from the substrate, which includes at least some of the dissolved material. Some material that is not dissolved by the composition may also be removed, since the composition has dissolved a portion of the material that binds the undissolved material to the substrate.

[0028] The composition may further comprise a surfactant. The surfactant can provide improved wettability of the material to be dissolved by the composition. Surfactants may include ethoxylated glycerol / fatty acid esters, such as ethoxylated glyceryl fatty acid esters (e.g., PEG 20 glyceryl laurate, PEG 20 glyceryl oleate, PEG 20 glyceryl oleate and PEG 20 glyceryl stearate), sorbitol esters and ethoxylated sorbitol esters (e.g., sorbitol monolaurate and sorbitol trioleate), monooleate, dioleate, PEG-alkoxylated block polymers, alkoxylated alcohols, alkoxylated alkylphenols, alkoxylated amines, alkoxylated amides, alkoxylated fatty acid esters, alkoxylated oils, fatty acid esters, alkoxylated fatty acids, sorbitol derivatives, alkylaryl sulfonates, alkylaryl sulfonic acids, carboxylated alcohol ethoxylates, alkylphenol ethoxylates, carboxylated ethoxylates, carboxylic acids, diphenyl sulfonate derivatives, olefin sulfonates, phosphate esters, phosphorus-containing organic derivatives, anionic surfactants (e.g., sodium dodecyl sulfate), and quaternary salt surfactants, or any combination thereof.

[0029] The surfactant may be as little as 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, or 1.0 wt% of the total weight of the composition, or as much as 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, or 2.0 wt%, or may be in any range defined between any two of the above values, for example, 0.1 wt% to 2.0 wt%, 0.2 wt% to 1.8 wt%, 0.4 wt% to 1.6 wt%, 0.6 wt% to 1.4 wt%, or 0.8 wt% to 1.2 wt%.

[0030] The composition may further comprise a thickener. The thickener provides sufficient viscosity to allow the composition to adhere to a non-horizontal substrate. This allows the composition to remain in contact with, for example, a vertically painted substrate for a sufficient time to allow the composition to break down and dissolve at least some of the paint and to remove the paint from the substrate below. The thickener may include organoclay, fatty acid salts, pyrolytic silica, paraffin wax, and alkylated, esterified, and alkoxylated cellulose derivatives, such as ethyl cellulose, cellulose acetate butyrate, hydroxypropyl methylcellulose, and methylcellulose, or combinations thereof.

[0031] The thickener may be as little as 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, or 1.0 wt% of the total weight of the composition, or as much as 1.2 wt%, 1.4 wt%, 1.6 wt%, 1.8 wt%, or 2.0 wt%, or may be in any range between any two of the above values, for example, 0.1 wt% to 2.0 wt%, 0.2 wt% to 1.8 wt%, 0.4 wt% to 1.6 wt%, 0.6 wt% to 1.4 wt%, or 0.8 wt% to 1.2 wt%.

[0032] The composition may further include additives, such as activators and corrosion inhibitors, or neutralizers. Activators can chemically erode organic matter in materials and improve the properties of the composition. Neutralizers can prevent substrate corrosion caused by the corrosiveness of some activators or surfactants.

[0033] Any of the above compositions can be applied to a substrate to clean or peel material from the substrate. The material to be cleaned or peeled from the substrate may include, but is not limited to, paints (cured, partially cured, or uncured), inks such as flexographic and gravure inks, coatings such as acrylic and alkyd resin coatings, and polymer resins such as polyester resins. The composition can be applied to the substrate by, for example, spraying, brushing, or pouring. The substrate may be formed of metal, wood, or polymer.

[0034] As used herein, the phrase “any range defined between any two of the above values” literally means any range that can be selected from any two values ​​listed preceding this phrase, regardless of whether the values ​​are in the lower or higher part of the list. For example, a pair of values ​​can be selected from two lower values, two higher values, or a lower and a higher value.

[0035] Although the invention has been described with respect to exemplary designs, further modifications may be made to the invention within the spirit and scope of this disclosure. Furthermore, this application is intended to cover deviations from this disclosure from the known or conventional practices within the field to which this invention pertains. Example

[0036] The following examples illustrate the effectiveness of compositions comprising a cosolvent according to this disclosure, the cosolvent comprising one or more caprolactam-derived solvents, and methods for cleaning or stripping materials from substrates using these solvents. The compositions are evaluated in relation to commercially available cleaning or stripping products, and to compositions using N-methylpyrrolidone as a cosolvent instead of one or more caprolactam-derived solvents.

[0037] Preparation of coated substrate Test the resistance of various compositions and cleaning paint removers or products (collectively, “Paint Removers”) to up to five coatings on wood substrates, metal substrates, or both. Wood substrates are pine boards prepared by sanding with 240-grit sandpaper. Metal substrates are cold-rolled steel sheets pretreated with zinc phosphate. The substrates are cleaned to remove debris, dirt, dust, or grease.

[0038] The five coatings are: solvent-based alkyd resin paint (SB alkyd resin), solvent-based 2K epoxy resin (SB 2K epoxy resin), waterborne 2K epoxy resin (WB 2K epoxy resin), waterborne acrylic architectural paint (WB acrylic), and waterborne polyurethane dispersion industrial coating (WB PUD).

[0039] According to ASTM D6189, the paint is applied to the substrate using a high-flow-low-pressure (HVLP) spray gun. The paint is applied in three layers to each substrate, with the second layer having a different tint than the first and third layers, allowing the effectiveness of the paint remover to be determined on different coatings. Each layer is applied to a thickness of approximately 2–2.5 mils (dry film thickness), for a total coating thickness of approximately 6–7.5 mils (dry film thickness).

[0040] Paint remover Caprolactam-derived cosolvents N-methylcaprolactam, N-ethylcaprolactam, and N-butylcaprolactam were added to various paint remover formulations. N-methylpyrrolidone was also added to various paint remover formulations. Formulations were based on butyl propionate and ethyl 3-ethoxypropionate solvents (Formulation 1) or acetone, 1,3-dioxolane, and propylene carbonate solvents (Formulation 2). Each formulation was prepared by adding the base solvent to a cosolvent in a large glass container and mixing it with a 15 wt% paraffin solution, a cellulose ether thickener, a sodium dodecyl sulfate surfactant, and an ethanolamine neutralizer. The 15 wt% paraffin solution was obtained from Sasol, Hamburg, Germany. ® Sasol Wax (Spray 30-G) from Performance Chemicals was prepared by adding it to VM&P naphtha and stirring at 1,000 RPM for 30–45 minutes until the wax was completely dissolved. Cellulose ethers were purchased from ChemPoint, Bellevue, WA, using Methocel. TM 311. Stir the mixture with a mechanical stirrer until all components are incorporated, then filter through a 125-micron paint filter to remove any undissolved particles. In the case of N-butylcaprolactam, after adding 15 wt% paraffin solution and cellulose ether thickener, but before adding the remaining components, heat the formulation to 65°C for ten minutes, then cool to room temperature to establish the necessary viscosity distribution.

[0041] Example 1 - Paint Remover Efficiency - Residence Time at Room Temperature (15 minutes) Five paint remover formulations were prepared as described above. Three were based on formulation 1 and included N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidine as a co-solvent, with the weight percentage of each component shown in Table 1; two were based on formulation 2 and included N-methylcaprolactam or N-ethylcaprolactam as a co-solvent, with the weight percentage of each component shown in Table 2. Using a solvent-resistant brush, the five paint remover formulations were applied to wood or metal substrates, brushing in one direction from top to bottom. For comparative purposes, Rust-Oleum was used... ® Automotive stripper and Blue Bear ® Paint & Urethane stripper is similarly applied to wood or metal substrates. Rust-Oleum® Automotivestripper is a highly effective dichloromethane-based stripper. Blue Bear® Paint & Urethane stripper contains 41% N-methylpyrrolidone.

[0042] Table 1 Table 2 At room temperature, after the paint remover has been left on the substrate for 15 minutes, the substrate is scraped off with a plastic paintscraper, and the degree of coating removal for each of the seven paint removers is evaluated according to ASTM D6189, as shown in Table 3: Table 3 The results are shown in Table 4: Table 4 As shown in Table 4, only the commercially available dichloromethane-based stripper is effective for alkyd and waterborne epoxy coatings. It is also the most effective for all coatings. However, the use of dichloromethane-based strippers is generally limited by the serious toxicity issues of dichloromethane. Formulation 1 is as effective as commercially available N-methylpyrrolidone-based strippers. Formulation 2 is less effective than formulation 1; therefore, formulations containing N-methylcaprolactam or N-ethylcaprolactam as cosolvents are as effective in coating removal applications as those containing N-methylpyrrolidone as a cosolvent.

[0043] Example 2 - Paint Remover Efficiency - Residence Time at High Temperature for One Hour Three paint remover formulations were prepared as described above, with the weight percentage of each component shown in Table 5. These three formulations are based on Formulation 1 as described above and include N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidine as a co-solvent. As described above, the three paint remover formulations were applied to a metal substrate together with SB alkyd resin or WB 2K epoxy resin coating. This resulted in two coatings. In Example 1, after fifteen minutes at room temperature, the formulation containing N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidine as a co-solvent was completely ineffective in removing the paint.

[0044] Table 5 At a high temperature of approximately 120℉, after a 15-minute dwell time with the paint remover on the substrate, the substrate was scraped off with a plastic paint scraper. The degree of coating removal for each of the three paint removers was evaluated using the standards shown in Table 2. If any coating residue remained after 15 minutes, the coated substrate was exposed to a high temperature of approximately 120℉ again for another 15 minutes and scraped off with a plastic paint scraper. The degree of coating removal for each paint remover was evaluated using the standards shown in Table 3. This process was repeated until the coating was removed from the substrate, or until a total dwell time of 60 minutes had elapsed. The results are shown in Table 6.

[0045] Table 6 As shown in Table 6, formulations containing N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidine as cosolvents were highly effective in removing SB alkyd resin coatings at longer times and higher temperatures. Formulations containing N-methylpyrrolidine as a cosolvent removed all SB alkyd resin coatings within fifteen minutes, while formulations containing N-methylcaprolactam or N-ethylcaprolactam as cosolvents removed all SB alkyd resin coatings within thirty minutes. Based on observations of coating wrinkling, formulations containing N-methylcaprolactam as a cosolvent were found to be more effective than those containing N-ethylcaprolactam. None of the three formulations showed effectiveness in removing WB 2K epoxy resin coatings, even at elevated temperatures with a total residence time of one hour.

[0046] Therefore, it has been shown that formulations of some coating types, including N-methylcaprolactam or N-ethylcaprolactam, have the potential to replace dichloromethane, requiring only slightly longer residence times and heat.

[0047] Example 3 - Paint Remover Efficiency - Residence Time at Room Temperature (15 minutes) - N-Butylcaprolactam A paint remover formulation based on Formulation 1 and containing N-butylcaprolactam as a cosolvent was prepared according to the method described above. The weight percentages of each component are shown in Table 7. The paint remover formulation was applied to a metal substrate with an SB 2K epoxy resin or WB acrylic coating and to a wood substrate with a WB acrylic or WB PUD coating, as described above. These are three coatings, and in Example 1, they were at least partially removed by the formulation containing N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidine as a cosolvent after fifteen minutes at room temperature.

[0048] Table 7 At room temperature, after a 15-minute leave period of paint remover on the substrate, the substrate was scraped off with a plastic paint scraper, and the degree of coating removal was evaluated according to ASTM D6189, as shown in Table 2. The results are shown in Table 8: Table 8 As shown in Tables 8 and 4, formulations containing N-butylcaprolactam as a cosolvent are approximately as effective as those containing N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidone in removing WB acrylic and WBPUD coatings. Formulations containing N-butylcaprolactam as a cosolvent are slightly less effective than those containing N-methylcaprolactam, N-ethylcaprolactam, or N-methylpyrrolidone in removing SB 2K epoxy coatings. Therefore, formulations containing N-methylcaprolactam, N-ethylcaprolactam, or N-butylcaprolactam as a cosolvent impart similar paint-removing properties to N-methylpyrrolidone.

Claims

1. A composition for use in cleaning or peeling materials from a substrate, The substrate is wood or metal; The material is selected from alkyd resin coatings and coatings, epoxy coatings and coatings, acrylic coatings and coatings, polyurethane coatings and coatings, and combinations thereof; and The composition comprises: The main solvent comprises butyl propionate and ethyl 3-ethoxypropionate; and A cosolvent, wherein the cosolvent comprises one or more caprolactam-derived solvents, wherein the caprolactam-derived solvent comprises N-ethylcaprolactam.

2. The use according to claim 1, wherein the concentration of the co-solvent is 5% to 49% by weight of the composition.

3. The use according to claim 1 or 2, wherein the composition further comprises a surfactant.

4. The use according to claim 1 or 2, wherein the composition further comprises a thickener.

5. A method for cleaning materials from a substrate, the method comprising: The composition is applied to the substrate for a period of time to dissolve at least some of the material. The substrate is a wood or metal substrate; The material is selected from alkyd resin coatings and coatings, epoxy coatings and coatings, acrylic coatings and coatings, polyurethane coatings and coatings, and combinations thereof; and The composition comprises a main solvent and a co-solvent, the main solvent comprising butyl propionate and ethyl 3-ethoxypropionate, and the co-solvent comprising one or more caprolactam-derived solvents, the caprolactam-derived solvent comprising N-ethylcaprolactam; as well as Remove the composition containing dissolved material from the substrate.

6. The method of claim 5, wherein the composition further comprises at least one of the following: a surfactant and a thickener.

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