Method for removing bonded substrates

Abstract

The present invention relates to a method for separating two adhesively bonded substrates, particularly by treating them with a release agent. Furthermore, the present invention relates to the use of the method in recycling components of electronic devices. The method comprises the steps of (1) treating the two adhesively bonded substrates with a release agent containing acetone and / or oleic acid at a temperature of 20°C to 90°C, and (2) removing the substrates from the adhesive.

Description

[Technical Field]

[0001] The present invention relates to a method for delaminating substrates bonded with adhesives, particularly by treatment with a release agent. Furthermore, the present invention relates to the use of the said method in recycling components of electronic devices. [Background technology]

[0002] Adhesives are used to bond parts in a wide range of fields, including aerospace, electronics, automotive, construction, sports, and packaging. Adhesives can be used to bond various materials such as metals, polymers, ceramics, cork, and rubber. However, one drawback of adhesive bonding is its "permanence," meaning the bond is not easily removed. In most cases, the bond cannot be broken without discarding the substrate.

[0003] Currently, widely used advanced materials such as ceramics, precious metals, and composite materials are typically expensive, leading to increased demand for recyclability for economic and environmental reasons. Therefore, the development of new technologies and processes to facilitate the recycling and repair of adhesive-bonded assemblies is of great interest to the industry. Recycling becomes much easier if adhesive bonds can be broken without damaging the components. Furthermore, from an environmental perspective, it is necessary to separate the bonds between bonding substrates, allowing for the qualitatively high-quality reuse of different materials.

[0004] As recycling becomes a necessity and a global issue, reversible adhesives or releases have been developed depending on the bonding properties of the adhesive.

[0005] For example, WO 01 / 30932 describes a method for separating an adhesive bond with an adhesive. The adhesive bond comprises a thermosoftening thermoplastic adhesive layer or a thermally cleavable thermosetting adhesive layer and a primer layer, the primary layer comprising nanoscale particles that can be heated by an alternating electromagnetic field.

[0006] WO-A 01 / 28771 describes a microwave-curable composition containing particles that can absorb microwaves at a Curie temperature higher than the curing temperature of the composition.

[0007] US20160068720A1 discloses a peelable adhesive composition comprising (A) a hydrosilylation reaction product obtained by a reaction between a vinyl group on 1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane and a terminal Si-H hydrogen on a silane or siloxane having terminal Si-H hydrogens, (B) a crosslinking agent for the hydrosilylation reaction product, and (C) a metal catalyst and / or radical initiator. The peelable adhesive composition maintains its adhesive strength even at temperatures above 300°C and is mechanically peelable at room temperature with a force of less than 5 N / 25 mm. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 01 / 30932 [Patent Document 2] International Publication No. 01 / 28771 [Patent Document 3] U.S. Patent Application Publication No. 20160068720 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, when used in demanding applications such as electronic devices that require an adhesive portfolio excellent in adhesion strength, impact resistance, and ease of application, the prior art methods have the drawbacks that the cost of the adhesive increases and the adhesion strength and / or impact resistance are insufficient. Further, in the prior art methods using special heating devices, the cost and energy also increase. Considering the existing problems in providing alternative and / or improved methods for peeling adhesively bonded substrates, there is still a need in the art for a method of peeling adhesively bonded substrates that is suitable for industrial scale applications and eliminates the need for costly processing.

Means for Solving the Problems

[0010] In a first aspect, the present invention is a method for peeling a substrate adhered by an adhesive, comprising the following steps: (1) treating two substrates adhered by an adhesive with a release agent containing acetone and / or oleic acid at a temperature of 20°C to 90°C, and (2) removing the substrate from the adhesive The present invention satisfies this requirement by providing a method including these steps.

[0011] ​​​​​​​​​​​​​​​A method for removing substrates bonded with an adhesive includes, as a first step, a step of treating two substrates bonded with an adhesive with a release agent containing acetone and / or oleic acid at a temperature of 20°C to 90°C.

[0015] As used herein, the term “treat” means that the release agent comes into contact with at least the interface between the substrate and the adhesive by conventional methods such as dipping, brushing, or spraying. In one preferred embodiment, the two substrates bonded together with the adhesive are dipped in the release agent.

[0016] In one embodiment, the treatment time for the substrate with the release agent is 0.5 to 60 minutes, preferably 1 to 30 minutes.

[0017] The stripping agent comprises acetone and / or oleic acid, and may further comprise at least one additive selected from water, alkanolamines, nonionic surfactants, and combinations thereof.

[0018] Acetone may be present in the stripping agent in an amount of at least 50% by weight, preferably at least 95%, more preferably at least 99%, and particularly at least 99.5%, based on the weight of the stripping agent.

[0019] Oleic acid may be present in the release agent in an amount of 1% to 50% by weight, preferably 5% to 30% by weight, based on the weight of the release agent. If present, the release agent may contain water, preferably deionized water, in an amount of 0.01 to 50% by weight, preferably 0.1 to 40% by weight, based on the weight of the release agent.

[0020] Examples of alkanolamines used as additives in stripping agents include ethanolamine, diethanolamine, triethanolamine, propanolamine, dipropanolamine, and tripropanolamine. In one preferred embodiment, the alkanolamine is triethanolamine.

[0021] If present, the release agent may contain at least one alkanolamine in an amount of 1 to 50% by weight, preferably 5 to 40% by weight, based on the weight of the release agent.

[0022] The nonionic surfactant preferably comprises a primary alcohol having alkoxylated, advantageously ethoxylated and / or propoxylated, particularly preferably 8 to 22 carbon atoms, especially 8 to 18 carbon atoms, and an average of 1 to 20 moles, preferably 1 to 12 moles, of alkylene oxide, particularly preferably 5 to 15 moles per mole of alcohol, advantageously ethylene oxide (EO), where the alcohol group may be linear, or preferably methyl-branched at the 2 position, or the mixture may contain both linear and methyl-branched groups, which usually arise from oxoalcohol groups. Particularly preferred, however, are alcohol ethoxylates having linear groups from alcohols having 8 to 18 carbon atoms, such as isodecyl or isotridecyl alcohols, with an average of 2 to 8 EO or 5 to 15 EO per mole of alcohol. Examples of preferred ethoxylated alcohols include C having 3EO or 4EO. 10~14 - C containing alcohol, 7EO 9~14 - C containing alcohol, 3EO, 5EO, 7EO or 8EO 13~15 - Alcohol and C having 3EO, 5EO or 7EO 12~18 - Alcohols, and mixtures thereof, as well as C having 3EO 12~14 - C containing alcohol and 5EO 12~18 - Examples include mixtures of alcohols. The cited degree of ethoxylation constitutes a statistical mean of the total or partial number for a particular product. Preferred alcohol ethoxylates have a narrow congener distribution (narrow range of ethoxylates, NREs).

[0023] Furthermore, substances generally known to those skilled in the art as non-ionic emulsifiers can also be regarded as non-ionic surfactants. In this regard, non-ionic surfactants include, as hydrophilic groups, for example, polyol groups, polyether groups, polyamine groups or polyamide groups, or combinations of the above groups. Such compounds are, for example, C8-C 22 -alkyl-mono- and -oligoglycosides and their ethoxylated analogs addition products, 2 to 30 moles of ethylene oxide and / or 0 to 10, especially 0 to 5 moles of propylene oxide to fatty alcohols having 8 to 22 carbon atoms, to fatty acids having 12 to 22 carbon atoms, and to alkylphenols having an alkyl group with 8 to 15 carbon atoms, C of products obtained by adding 1 to 30 moles of ethylene oxide to glycerin 12 ~C 22 -fatty acid monoesters and diesters, and products obtained by adding 5 to 60 moles of ethylene oxide to castor oil and hydrogenated castor oil.

[0024] Also, weakly foaming non-ionic surfactants having alternating ethylene oxide and alkylene oxide units can be used. Among these, surfactants having an EO-AO-EO-AO block in which 1 to 10 EO or AO groups are bonded together respectively before the blocks of other groups continue are preferred. Examples of these are surfactants of the following general formula. [Chemical formula]

[0025] In the formula, R 1 represents a linear or branched, saturated or mono-unsaturated or poly-unsaturated C 6-24 -alkyl group or alkenyl group, and each group R 2 or R 3 is independently selected from -CH3, -CH2CH3, -CH2CH2-CH3, -CH(CH3)2, and the indices w, x, y, z independently represent integers from 1 to 6. These are the corresponding alcohols R 1-OH and ethylene oxide or alkylene oxide can be produced by known methods. The group R in the previous formula 1 This varies depending on the origin of the alcohol. When a natural source is used, the base R 1 R in the above formula is preferred to have an even number of carbon atoms, is generally unbranched, and is a naturally occurring linear alcohol having 12 to 18 carbon atoms, such as coconut, palm, animal fat, or oleyl alcohol. Alcohols available from synthetic sources are, for example, Guerbet alcohols, or mixtures of a linear group and a methyl-branched group, typically found in oxo alcohols. Regardless of the type of alcohol used in the production of the nonionic surfactant contained in the agent, R in the above formula is preferred. 1 The agents of the present invention are preferred to represent alkyl groups having 6 to 24, preferably 8 to 20, particularly preferably 9 to 15, and especially 9 to 11 carbon atoms. In addition to propylene oxide, butylene oxide in particular can become alkylene oxide units alternating with ethylene oxide units in nonionic surfactants. However, R 2 or R 3 Other alkylene oxides selected independently from -CH2CH2CH3 or -CH(CH3)2 are also suitable.

[0026] Furthermore, nonionic block copolymers are considered nonionic surfactants, such as those described in U.S. Patent No. 6,677,293, which is incorporated herein by reference in its entirety. Herein, for example, they may relate to AB-, AA'B-, ABB'-, ABA'-, or BAB'- block copolymers, where A and A' represent hydrophilic blocks and B and B' represent hydrophobic blocks. Blocks A and A' may independently be polyalkylene oxides, particularly polypropylene oxide or polyethylene oxide, polyvinylpyridine, polyvinyl alcohol, polymethyl vinyl ether, polyvinylpyrrolidine, or polysaccharides. Blocks B and B' are independently of each other and may be optionally substituted alkyl groups, which can be obtained, for example, by polymerizing units selected from the group consisting of 1,3-butadiene, isoprene, all isomers of dimethylbutadiene, 1,3-pentadiene, 2,4-hexadiene, α-methylstyrene, isobutylene, ethylene, propylene or styrene, or mixtures thereof. The molecular weights of blocks A, A', B, and B' are preferably 500 to 50,000 g / mol, independently of each other. According to the present invention, it is preferable that at least one of blocks A and A' is an alkylene oxide.

[0027] Another class of preferred nonionic surfactants that can be used alone or in combination with other nonionic surfactants are alkoxylated, preferably ethoxylated, or ethoxylated and propoxylated fatty acid alkyl esters, particularly fatty acid methyl esters, which preferably contain 1 to 4 carbon atoms in the alkyl chain.

[0028] Furthermore, as an additional nonionic surfactant, the general formula RO(G) xAlkyl glycosides satisfying the following conditions can also be added. Here, R represents a primary linear or methyl-branched, particularly 2-methyl-branched, aliphatic group containing 8 to 22 carbon atoms, and G represents a glycose unit containing 5 or 6 carbon atoms, preferably glucose. The degree of oligomerization x, which defines the distribution of monoglycosides and oligoglycosides, is any value from 1 to 10, preferably from 1.2 to 1.4.

[0029] Amine oxide-type nonionic surfactants, such as N-cocoalkyl-N,N-dimethylamine oxide and N-fat alkyl-N,N-dihydroxyethylamine oxide, and fatty acid alkanolamides may also be suitable.

[0030] Other suitable surfactants are polyhydroxy fatty acid amides corresponding to the following formula: [ka]

[0031] In the formula, RCO is an aliphatic acyl group having 6 to 22 carbon atoms, R 1 [Z] represents hydrogen, a C1-C4 alkyl group, or a hydroxyalkyl group, and [C3-C10] represents a linear or branched polyhydroxyalkyl group with 3-10 hydroxyl groups. Polyhydroxy fatty acid amides are known substances and are usually obtained by reductive amination of reducing sugars with ammonia, alkylamines, or alkanolamines, followed by acylation with fatty acids, fatty acid alkyl esters, or fatty acid chlorides.

[0032] The polyhydroxy fatty acid amide group also includes compounds corresponding to the following formula: [ka]

[0033] In the formula, R is a linear or branched alkyl or alkenyl group having 7 to 12 carbon atoms, 1R is a linear, branched, or cyclic alkyl or aryl group having 2 to 8 carbon atoms. 2 C is a linear, branched, or cyclic alkyl group, or an aryl group or oxyalkyl group having 1 to 8 carbon atoms. 1~4 [Z] is preferably an alkyl group or a phenyl group, and [Z] is a linear polyhydroxyalkyl group in which the alkyl chain is substituted with at least two hydroxyl groups, or an alkoxylated, preferably ethoxylated or propoxylated derivative of that group.

[0034] [Z] is preferably obtained by reductive amination of a reducing sugar, such as glucose, fructose, maltose, lactose, galactose, mannose, or xylose. The N-alkoxy- or N-aryloxy-substituted compound may then be converted to the desired polyhydroxy fatty acid amide by reacting with a fatty acid methyl ester in the presence of an alkoxide as a catalyst.

[0035] Furthermore, usable nonionic surfactants are end-capped poly(oxyalkylated) surfactants, as shown in the following formula. [ka]

[0036] Here, R 1 and R 2 R represents a linear or branched hydrocarbon group having 1 to 30 carbon atoms, saturated or unsaturated, aliphatic or aromatic. 3 R represents H or methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl or 2-methyl-2-butyl group, x represents a value from 1 to 30, and k and j represent a value from 1 to 12, preferably from 1 to 5. 3 The case where x ≥ 2 is different. 1 and R 2The group R3 is preferably a linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon group having 6 to 22 carbon atoms, with groups having 8 to 18 carbon atoms being particularly preferred. H, -CH3, or -CH2CH3 are particularly preferred for the group R3. Particularly preferred values ​​of x are in the range of 1 to 20, and more specifically in the range of 6 to 15.

[0037] In a particularly preferred embodiment, the nonionic surfactant is an addition product of alkylene oxide units, particularly ethylene oxide (EO) and / or propylene oxide (PO) units, on an alkylphenol, wherein the alkyl group of the alkylphenol contains 6 to 18 carbon atoms, particularly preferably 6 to 12 carbon atoms, mainly 8, 9, or 10 carbon atoms, preferably 1 to 18 ethylene oxide (EO) units, particularly preferably 5 to 15 EO units, mainly 8, 9, or 10 EO units, added to the alkylphenol group (the values ​​cited herein are average values), and the alkyl group of the alkylphenol may be linear or methyl-branched at the 2-position, as is typically present in oxoalcohol groups, or may contain linear and methyl-branched groups in a mixture. In a particularly preferred embodiment, the nonionic surfactant is a product of adding an average of 9 EO units to nonylphenol, where the alkyl group and polyethylene group are preferably located meta relative to each other. This type of product is available, for example, under the name DISPONIL NP9 (BASF, Germany).

[0038] In a particularly preferred embodiment, the nonionic surfactant is an addition product of ethylene oxide (EO) units to a fatty alcohol, the fatty alcohol preferably containing 10 to 22 carbon atoms, particularly preferably 14 to 20 carbon atoms, mainly 16 to 18 carbon atoms, and preferably 4 to 24 ethylene oxide (EO) units, particularly preferably 10 to 22 EO units, mainly 11, 12, 13, 19, 20, or 21 EO units are added to the fatty alcohol. Particularly preferred products consisting of C16-18 alcohols having 12 or 20 EO units are available, for example, under trade names EUMULGIN B1 or EUMULGIN B2 (BASF, Germany).

[0039] In a particularly preferred embodiment, the nonionic surfactant is a product obtained by adding ethylene oxide (EO) units to a fatty alcohol, the fatty alcohol preferably containing 8 to 22 carbon atoms, particularly preferably 10 to 20 carbon atoms, mainly 12 to 18 carbon atoms, and preferably 3 to 15 ethylene oxide (EO) units, particularly preferably 5 to 11 EO units, mainly 6, 7, 8, 9, or 10 EO units are added to the fatty alcohol. Particularly preferred products consisting of C12-18 alcohols having 7 or 9 EO units are available, for example, under trade names DEHYDOL LT7 and DEHYDOL 100 (BASF, Germany).

[0040] In a particularly preferred embodiment, the nonionic surfactant is a product obtained by adding ethylene oxide (EO) units to a fatty alcohol, the fatty alcohol preferably containing 18 to 26 carbon atoms, particularly preferably 20 to 24 carbon atoms, mainly 22 carbon atoms, and preferably 6 to 16 ethylene oxide (EO) units, particularly preferably 8 to 12 EO units, mainly 9, 10, or 11 EO units are added to the fatty alcohol. A particularly preferred product consisting of a C22-alcohol having 10 EO units is available, for example, under the trade name MERGITAL B10 (BASF, Germany).

[0041] In a particularly preferred embodiment, the nonionic surfactant is a product obtained by adding ethylene oxide (EO) units and propylene oxide units to a fatty alcohol, the fatty alcohol preferably containing 6 to 18 carbon atoms, particularly preferably 10 to 16 carbon atoms, mainly 10 to 12 or 12 to 14 carbon atoms, preferably 1 to 10, particularly preferably 3 to 7, mainly 4, 5 or 6 EO units, and preferably 1 to 10, particularly preferably 2 to 6, mainly 3, 4, 5 or 6 PO units are added to the fatty alcohol. In a preferred embodiment, the nonionic surfactant according to this specification is a block copolymer, preferably with EO units added to the fatty alcohol followed by PO units, and the alkyl group of the fatty alcohol may be linear or have methyl branching at the 2 position, or may contain groups having linear and methyl branching in the form of a mixture typically present in the oxo alcohol group. A particularly preferred product consisting of C12-C14 alcohols having five EO units and four PO units is available, for example, under the name DEHYPPON LS 54 (BASF, Germany). A more particularly preferred product consisting of C10-12 alcohols having five EO units and five PO units is available, for example, under the name BIODAC 2 / 32 (Sasol, Germany).

[0042] Furthermore, in preferred embodiments of the present invention, the nonionic surfactant is a fluorinated or fluorine-containing nonionic surfactant. Herein, particularly preferably, is an addition product of alkylene oxide units on an alkyl alcohol; in particular, ethylene oxide (EO) units and / or propylene oxide units, wherein the alkyl alcohol preferably contains 4 to 20 carbon atoms, particularly preferably 6 to 18 carbon atoms, and preferably 1 to 18 carbon atoms, particularly preferably 2 to 16 EO units are added to the alkyl alcohol, and the compound, preferably alkyl group, contains at least 1 fluorine atom, preferably at least 5 fluorine atoms, particularly 5 to 30 fluorine atoms. In particularly preferred embodiments, the compound or mixture of compounds is of formula F(CF2) 1-7 CH2CH2O(CH2CH2O) 1-15It contains H. Such nonionic surfactants are available, for example, under the name ZONYL FSO 100 (Dupont, France).

[0043] According to the present invention, in certain embodiments, the hydroxyl group of the above-mentioned nonionic surfactant having a hydroxyl group can be partially or completely etherified or esterified. In this regard, ether bonds to C1-6 alkyl groups, preferably methyl, ethylisopropyl, or tert-butyl groups are particularly present. Preferred ester bonds include ester bonds to C1-6 alkane carboxylic acids, particularly acetic acid or maleic acid.

[0044] If present, the stripping agent may contain at least one nonionic surfactant in an amount of 1% to 50% by weight, preferably 5% to 40% by weight, based on the weight of the stripping agent.

[0045] In one embodiment, the stripping agent comprises or consists of acetone and water. Preferably, the stripping agent comprises or consists of at least 90%, preferably at least 99%, of acetone and 10% or less, preferably 1% or less, of water, based on the weight of the stripping agent.

[0046] In another embodiment, the release agent comprises or consists of oleic acid and water. Preferably, the release agent comprises or consists of at least 80%, preferably at least 90%, of oleic acid and 20% or less, preferably 10% or less, based on the weight of the release agent.

[0047] In yet another embodiment, the stripping agent comprises or consists of oleic acid, water, an alkanolamine, and a nonionic surfactant. Preferably, the stripping agent comprises or consists of 1% to 50% by weight, preferably 5% to 30% by weight, of oleic acid, 1% to 50% by weight, preferably 5% to 30% by weight, of at least one alkanolamine, and 1% to 50% by weight, preferably 5% to 40% by weight, of at least one nonionic surfactant, based on the weight of the stripping agent.

[0048] The method for producing the release agent of the present invention is not particularly limited, and the order of addition of the essential and optional components is not restricted. A preferred production method is, for example, to add the essential components to an aqueous solvent, followed by the addition of the optional components, and then to stir the resulting mixture at room temperature.

[0049] The method of the present invention is carried out by bringing the above-described release agent into contact with at least one substrate bonded by an adhesive. The surfaces of the substrate and adhesive that come into contact with the release agent can be cleaned and removed as necessary to prevent the adhesion of oil, dirt, metal powder (generated during wear or molding), etc. Therefore, the method of the present invention may include a step of cleaning the substrate and adhesive before step (1). Cleaning can be carried out by any method, and industrially common cleaning methods such as alkaline cleaning can be applied. After cleaning, the substrate and adhesive are washed with water to wash away alkaline components, etc. from their surfaces, and then the release agent of the present invention is brought into contact with the surface.

[0050] The release agent treatment is preferably carried out at a temperature of 20 to 90°C, preferably 20 to 70°C. When using a release agent containing oleic acid, it is more preferable to treat the substrate at a temperature of 30 to 70°C, particularly 40 to 60°C. The treatment time depends on the properties of the substrate material and base material, but is usually 3 to 120 minutes, preferably 5 to 60 minutes.

[0051] Depending on the structure and complexity of the substrate, the release agent can be applied to the bonded substrate by dipping, spraying, and / or brushing.

[0052] The adhesive that is peeled off the substrate is not particularly limited. Such adhesives may be thermoplastic adhesives or thermosetting adhesives. Preferably, the adhesive peeled off the substrate is selected from the group consisting of epoxy resins, acrylates, and polyurethanes.

[0053] The substrates may be the same or different, and each substrate is selected from the group consisting of metal, polymer, glass, ceramic, cork, and rubber.

[0054] Furthermore, a method for peeling off a substrate bonded with an adhesive further includes (2) the step of removing the substrate from the adhesive.

[0055] When separating the substrate from the adhesive, external force may or may not be used. For example, if the adhesive is completely separated from the substrate or dissolved in the release agent after step (1), external force may not be necessary. However, if at least a portion of the adhesive is still in contact with the substrate, external force may be used to completely detach or remove the adhesive. External force, such as liquid cleaning or mechanical force, is used to compensate for any remaining adhesive strength between the adhesive and the substrate.

[0056] In one embodiment, the tensile shear strength of the bonded substrate after step (1) is measured by ASTM-D1002 and is 5 MPa or less, preferably 4 MPa or less. In a preferred embodiment, the tensile shear strength of the bonded steel substrate after step (1) is measured by ASTM-D1002 and is 1 MPa or less, preferably 0.5 MPa or less. In another preferred embodiment, the tensile shear strength of the polycarbonate bonded substrate after step (1) is measured by ASTM-D1002 and is 3 MPa or less, preferably 2 MPa or less. In yet another preferred embodiment, the tensile shear strength of the bonded glass substrate after step (1) is measured by ASTM-D1002 and is 1 MPa or less, preferably 0.5 MPa or less.

[0057] After step (2), i.e., after the adhesive has been removed from the substrate, the method according to the present invention may include a step of cleaning the substrate and the adhesive. The cleaning may be carried out by any method, and industrially common cleaning methods such as alkaline cleaning can be applied. The cleaned substrate and adhesive are rinsed with water to wash away the surface release agent.

[0058] The adhesive substrate removal method of the present invention is suitable for recycling electronic device components such as mobile phones that are bonded with various conventional adhesives such as epoxy, acrylate, and polyurethane adhesives, and can be implemented on an industrial scale.

[0059] Naturally, it will be understood that all embodiments disclosed above in connection with the methods of the present invention are similarly applicable to the laminates and uses of the present invention, and vice versa.

[0060] The present invention will be further illustrated by the following embodiments, but will not be limited thereto. Unless otherwise indicated, the quantities shown herein are by weight. [Examples]

[0061] Examples Example 1 (according to the present invention) Samples were prepared by bonding two 100mm x 25mm substrates at room temperature using a commercially available adhesive according to Table 1. Each substrate had a thickness of 1.6mm, a bonding line of 0.25mm, and a bonding area with an overlap of 25 x 12.5mm. Next, the samples were immersed in a 5% oleic acid aqueous solution used as a release agent at 60°C for 30 minutes. After rinsing off the release agent with water, the substrates and adhesive were separated using an Instron tester, and the tensile shear strength (TSS) was tested at 23°C and 50% humidity in accordance with ASTM-D1002. The percentage decrease in TSS compared to the reference value was calculated. The test results are shown in Table 1.

[0062] Example 2 ( Example experiment ) Samples were prepared by bonding two substrates together using a commercially available adhesive according to Table 1. Each substrate had a thickness of 1.6 mm, a bonding line of 0.25 mm, and a bonding area with an overlap of 25 × 12.5 mm. Next, each sample was immersed in acetone (99.7% purity) used as a release agent for 30 minutes at 30°C. After rinsing off the release agent with water, the substrates and adhesive were separated using an Instron tester, and the tensile shear strength was tested at 23°C and 50% humidity in accordance with ASTM-D1002. The percentage decrease in TSS compared to the reference value was calculated. The test results are shown in Table 1.

[0063] Example 3 (according to the present invention) Samples were prepared by bonding two substrates together using a commercially available adhesive according to Table 1. Each substrate had a thickness of 1.6 mm, a bonding line of 0.25 mm, and a bonding area of ​​25 × 12.5 mm overlap. Next, each sample was immersed for 30 minutes at 60°C in an aqueous solution containing 1.24% triethanolamine, 0.6% oleic acid, 1.5% ethoxylated isodecanol, and 0.4% ethoxylated isotridecanol, which were used as release agents. After rinsing off the release agents with water, the substrates and adhesives were separated using an Instron tester, and the tensile shear strength was tested at 23°C and 50% humidity in accordance with ASTM-D1002. The percentage decrease in TSS compared to the reference value was calculated. The test results are shown in Table 1.

[0064] Example 4 (Comparative Example) Samples were prepared by bonding two substrates together using a commercially available adhesive according to Table 1. Each substrate had a thickness of 1.6 mm, a bonding line of 0.25 mm, and a bonding area of ​​25 × 12.5 mm overlap. Next, each sample was immersed in diethylene glycol (99.5% purity) used as a release agent at 60°C for 30 minutes. After rinsing off the release agent with water, the substrates and adhesive were separated using an Instron tester, and the tensile shear strength was tested at 23°C and 50% humidity in accordance with ASTM-D1002. The test results are shown in Table 1.

[0065] Reference example Samples were prepared by bonding two substrates together using a commercially available adhesive according to Table 1. Each substrate had a thickness of 1.6 mm, a bonding line of 0.25 mm, and a bonding area with an overlap of 25 × 12.5 mm. The samples were not treated with a release agent, and the substrates and adhesive were separated using an Instron testing machine. Tensile shear strength was then tested at 23°C and 50% humidity according to ASTM-D1002. The test results are shown in Table 1.

[0066] [Table 1]

[0067] 1 HHDD 3542 is a polyurethane hot melt adhesive available from Henkel. 2 HHDD 6010 is a two-part polyurethane adhesive available from Henkel. 3 HHDD 8540 is an acrylate adhesive available from Henkel.

[0068] As can be seen from Table 1, after treatment with the release agent of the present invention, the adhesive strength of the various bonded substrates decreased significantly, and they could be easily peeled off from the various adhesives. However, the diethylene glycol used in the comparative example could not efficiently separate the bonded substrates under similar conditions. Preferred embodiments of the present invention include the following: [1] A method for peeling off a substrate bonded with an adhesive, (1) A step of treating two substrates bonded together with an adhesive with a release agent containing acetone and / or oleic acid at a temperature of 20°C to 90°C, and (2) Steps to remove the substrate from the adhesive A method that includes this. [2] The method according to [1], wherein the stripping agent further comprises water, an alkanolamine, a nonionic surfactant, and at least one additive selected from combinations thereof. [3] The method according to [1] or [2], wherein the stripping agent comprises at least 95%, preferably at least 99%, of acetone based on the weight of the stripping agent. [4] The stripping agent comprises oleic acid, water, an alkanolamine, and a nonionic surfactant, as described in either [1] or [3]. [5] The method according to any one of [1] to [4], further comprising the step of washing the substrate before step (1) and / or after step (2). [6] The method according to any one of items [1] to [5], wherein the processing temperature in step (1) is 20°C to 70°C. [7] The adhesive is selected from the group consisting of epoxy resins, acrylates, and polyurethanes, according to the method of any one of [1] to [6]. [8] The method according to any one of [1] to [7], wherein the substrate is independently selected from the group consisting of metal, glass, polymer, ceramic, cork, and rubber. [9] Use of the method described in any one of items [1] to [8] in the recycling of electronic devices, preferably components of mobile phones.

Claims

1. A method for removing a substrate bonded with an adhesive, (1) A step of treating two substrates bonded together with an adhesive with a release agent containing oleic acid at a temperature of 20°C to 90°C, wherein the amount of oleic acid is 50% by weight or less based on the weight of the release agent, and (2) Step of removing the substrate from the adhesive Includes, Here, the adhesive is selected from the group consisting of acrylate adhesives and polyurethane adhesives.

2. The method according to claim 1, wherein the stripping agent further comprises at least one additive selected from water, alkanolamines, nonionic surfactants, and combinations thereof.

3. The method according to either claim 1 or 2, wherein the stripping agent comprises oleic acid, water, an alkanolamine, and a nonionic surfactant.

4. The method according to any one of claims 1 to 3, further comprising the step of washing a substrate before step (1) and / or after step (2).

5. The method according to any one of claims 1 to 4, wherein the processing temperature in step (1) is 20°C to 70°C.

6. The method according to any one of claims 1 to 5, wherein the substrate is independently selected from the group consisting of metal, glass, polymer, ceramic, cork, and rubber.

7. Use of the method according to any one of claims 1 to 6 in the recycling of components of electronic devices.

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