Copolymers and disassemblable adhesives

Abstract

To provide a copolymer that undergoes rapid main chain cleavage, and a rapidly decomposing adhesive using the copolymer. [Solution] A copolymer having repeating units derived from a cyclic ketene acetal monomer, repeating units derived from an allyl alcohol monomer, and repeating units derived from an acrylamide monomer, and a disassemblable adhesive using this copolymer.

Description

[Technical Field]

[0001] This invention relates to a main-chain cleavable copolymer and a disassemblable adhesive using this copolymer. [Background technology]

[0002] The chemical decomposition of polymer compounds is being applied to advanced functional materials such as disassemblable adhesives, resists, and self-healing materials, which utilize the changes in physical properties before and after decomposition, as well as to medical materials such as biocompatible materials and drug transport materials. Furthermore, in recent years, there has been a demand to achieve highly efficient chemical recycling and promote decomposition in nature by utilizing the chemical decomposition of polymer compounds, and these materials are expected to be environmentally friendly. Against this backdrop, molecular designs are being investigated that introduce weak covalent bonds, such as ester bonds and acetal bonds, into the main chain of polymer compounds in response to specific stimuli such as light, heat, acid, and base.

[0003] Therefore, a method of introducing ester bonds into the main chain by performing radical ring-opening polymerization using cyclic ketene acetals (hereinafter also called CKA) as monomers has attracted attention (Non-Patent Literature 1). By radical copolymerizing CKA with a vinyl monomer, ester bonds can be introduced into the main chain, and these ester bonds can be cleaved by hydrolysis using a strong base. Furthermore, the present inventors have proposed generating nucleophilic groups in the side chains of adjacent units, rather than directly cleaving the main chain, and inducing main chain cleavage by transesterification reactions between the main chain and side chains (Non-Patent Literature 2-5). However, CKA is decomposed and deactivated by hydroxyl groups (see Fig. 88(b) in Non-Patent Document 1, Non-Patent Document 6, etc.). Therefore, there were problems such as CKA being deactivated by reacting with water during storage, and the monomers that copolymerize with CKA being limited. In addition, CKA had to be stored in an inert gas atmosphere using a glove box or the like, and weighed and mixed with other polymerization reagents immediately before use.

[0004] In Patent Document 1, the present inventors have proposed a method for suppressing the decomposition of CKA by storing it in a hydrophobic vinyl polymer, a polymer having repeating units derived from CKA and repeating units derived from the hydrophobic vinyl polymer, and a polymer capable of main chain cleavage using a specific allyl alcohol monomer as the hydrophobic vinyl polymer. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent application No. 2023-148845 [Non-patent literature]

[0006] [Non-Patent Document 1] Antoine Tardy, Julien Nicolas, Didier Gigmes, Catherine Lefay, Yohann Guillaneuf, Radical Ring-Opening Polymerization: Scope, Limitations, and Application to (Bio)Degradable Materials, Chemical Reviews, 2017, 117(3), 1319-1406 [Non-Patent Document 2] Kaho Toyama, Yasuhiro Kosaka, "Synthesis of easily degradable vinyl polymers by copolymerization of allyl alcohol derivatives and cyclic ketene acetals," Proceedings of the Annual Meeting of the Society of Polymer Science, Japan, Vol. 71, No. 1, 2C10, May 2022. [Non-Patent Document 3] Kaho Toyama, Moe Kawauchi, and Yasuhiro Kosaka, "Rapid Degradation of Vinyl Polymers Using Intramolecular Transesterification Reactions Between Main Chain and Side Groups," Proceedings of the 71st Symposium on Polymer Science, 3B19, September 2022. [Non-Patent Document 4] Kaho Toyama, Yasuhiro Kosaka, "Creation of vinyl polymers that undergo main chain cleavage triggered by side group deprotection of adjacent units," Proceedings of the 72nd Symposium on Polymer Science, 2C13, September 2023. [Non-Patent Document 5] Yasuhiro Kohsaka, Kaho Toyama, Moe Kawauchi, Koki Naganuma, Fast and Selective Main-Chain Scission of Vinyl Polymers Using the Domino Reaction in the Alternating Sequence for Transesterification, ACS Macro Letters, 2024, 13(8), 1016-1021. [Non-Patent Document 6] Srinivasa Reddy Mothe, Lohitha Rao Chennamaneni, Jacqueline Tan, Freda CH Lim, Wenguang Zhao, Praveen Thoniyot, A Mechanistic Study on the Hydrolysis of Cyclic Ketene Acetal (CKA) and Proof of Concept of Polymerization in Water,Macromolecular Chemistry and Physics,2023,224(19),2300221. [Overview of the project] [Problems that the invention aims to solve]

[0007] The binary copolymer of allyl alcohol monomer and CKA proposed in Patent Document 5 can undergo main chain cleavage under conditions that have minimal adverse effects on the human body and the environment, such as aqueous acetic acid solution. However, the cleavage is slow, and there was a need to improve the cleavage speed (decomposition speed) when used as a disintegrating adhesive or the like. The object of this invention is to provide a copolymer that undergoes rapid main chain cleavage and a rapidly decomposing adhesive containing this copolymer. [Means for solving the problem]

[0008] The means to solve the above problems are as follows: 1. A repeating unit derived from a cyclic ketene acetal monomer represented by the following formula (1), and

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

Chemical Formula

[0009] The copolymer of the present invention can undergo main chain cleavage under relatively safe conditions, such as an aqueous solution of acetic acid. The copolymer of the present invention decomposes rapidly even under mild conditions, and the decomposition products are soluble in water, making it suitable as a decomposable adhesive. [Brief explanation of the drawing]

[0010] [Figure 1] A graph showing the time evolution of the size exclusion chromatogram in the decomposition test described in Example 1. [Figure 2] A photograph of the glass substrate after the disassembly test described in Example 4. [Figure 3] A photograph of the glass substrate after the disassembly test described in Example 5. [Figure 4] A photograph of the glass substrate after the disassembly test described in Example 6. [Modes for carrying out the invention]

[0011] The present invention will be described below. However, the following description is merely an example of the present invention and does not limit it in any way. The present invention is not limited to the embodiments described below, and within the scope of the invention and based on the technical concept of the invention, various modifications, changes, and improvements may be made to each disclosed element (including the elements described in the claims, specification, and drawings). Furthermore, within the scope of the claims of the present invention, various combinations, substitutions, or selections of each disclosed element are possible. In this specification, the notation "A~B" (where A and B are numerical values) means a numerical range that includes both ends of the range, i.e., "greater than or equal to A and less than or equal to B".

[0012] • Cyclic ketene acetal (CKA) The cyclic CKA used in this invention is represented by the following general formula (1). [ka] (In the formula, ring A is a 5- to 7-membered ring that may have substituents, and the substituents may form fused rings.)

[0013] Examples of CKAs represented by the general formula (1) below include the following: [Table 1-1]

[0014] [Table 1-2]

[0015] [Table 1-3]

[0016] [Table 1-4]

[0017] The above CKA can also be expressed as follows: [Table 2]

[0018] [Table 3]

[0019] [Table 4-1]

[0020] [Table 4-2]

[0021] In the radical polymerization of CKA, in addition to ring-opening polymerization that generates ester bonds in the main chain, conventional addition polymerization that generates a main chain consisting only of carbon atoms without ring opening may also occur. In the present invention, since the ester bonds of the main chain are used for polymer decomposition, it is preferable to use CKA, which allows for highly selective ring-opening polymerization. Therefore, from the viewpoint of selectivity for ring-opening polymerization, CKA12, CKA20, CKA22, CKA27, CKA29, and CKA31 are preferred as CKA, and from the viewpoint of resistance to hygroscopic decomposition in an atmospheric atmosphere and storage stability, CKA12, CKA22, and CKA29 are more preferred.

[0022] "Allyl alcohol monomers" The allyl alcohol monomer used in this invention is represented by the following formula (2). [ka] (In the formula, R represents a C1-C6 alkyl group, a C1-C6 haloalkyl group, a phenyl group, or a substituted phenyl group.) (W represents a hydrogen atom or a trialkylsilyl group.)

[0023] Here, a substituted phenyl group means a phenyl group that is substituted with one or more groups selected from alkyl groups, alkenyl groups, alkynyl groups, aryl groups, halogen atoms, haloalkyl groups, haloalkenyl groups, haloalkynyl groups, haloaryl groups, alkoxy groups, alkenyloxy groups, aryloxy groups, haloalkoxy groups, haloalkenyloxy groups, haloaryloxy groups, amino groups, alkylamino groups, arylamino groups, acyl groups, aroyl groups, arylacyl groups, acylamino groups, alkylsulfonyloxy groups, arylsulfenyloxy groups, heterocyclyl groups, heterocisyloxy groups, heterocisylamino groups, haloheterocyclyl groups, alkoxycarbonyl groups, alkylthio groups, alkylsulfonyl groups, arylthio groups, arylsulfonyl groups, aminosulfonyl groups, dialkylamino groups, and dialkylsulfonyl groups.

[0024] R represents a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 hydroxyalkyl group, a phenyl group, or a substituted phenyl group. Among these, a C1-C6 alkyl group is preferred due to the ease of monomer synthesis, and an ethyl group or a methyl group is more preferred. W represents a hydrogen atom or a trialkylsilyl group. Examples of alkyl groups in the trialkylsilyl group include C1-C6 alkyl groups, such as trimethylsilyl group, triethylsilyl group, and dimethyl-tert-butylsilyl group. Among these, a hydrogen atom or a trimethylsilyl group is preferred, and a trimethylsilyl group is more preferred.

[0025] "Acrylamide monomers" The acrylamide monomer used in this invention is represented by the following formula (3). [ka] (In the formula, R5 represents a hydrogen atom or a methyl group.) R6 represents a hydrogen atom, a C1-C6 alkyl group (where non-consecutive -CH2- groups may be replaced with -O- groups), or a C1-C6 haloalkyl group (where non-consecutive -CH2- groups may be replaced with -O- groups).

[0026] The acrylamide monomer represented by formula (3) has an amide structure and is therefore more hydrophilic than the CKA represented by formula (1) and the allyl alcohol monomer shown in formula (2). Therefore, using the acrylamide monomer represented by formula (3) improves the adhesive strength of the resulting copolymer through hydrogen bonding, expands the range of bondable materials, and accelerates aqueous decomposition due to improved hydrophilicity.

[0027] From the viewpoint of polymer adhesion and degradability, R6 is preferably a hydrogen atom, a C1-C3 alkyl group (where non-consecutive -CH2- may be replaced with -O-), or a C1-C3 haloalkyl group (where non-consecutive -CH2- may be replaced with -O-), more preferably a hydrogen atom, a methyl group, an ethyl group, a methoxy group, or an ethoxy group, and even more preferably a hydrogen atom or a methoxy group.

[0028] "Copolymer" The copolymer of the present invention has repeating units derived from CKA represented by formula (1), repeating units derived from an allyl alcohol monomer represented by formula (2), and repeating units derived from an acrylamide monomer represented by formula (3). The copolymer of the present invention only needs to have repeating units derived from formulas (1) to (3), and may also have repeating units derived from other copolymerizable monomers.

[0029] The copolymer of the present invention can be produced (polymerized) by a conventionally known radical polymerization reaction. The allyl alcohol monomer represented by formula (2) is a hydrophobic vinyl monomer whose saturated dissolution amount is less than 10 g when dissolved in 100 g of deionized water at 25°C until saturated. Therefore, CKA can be stored in the allyl alcohol monomer while suppressing its decomposition (Patent Document 1).

[0030] Here, among the structures of the copolymer of the present invention, the structure formed by the polymerization of CKA and allyl alcohol monomers in a specific order allows for transesterification between the main chain and side chains, and this transesterification reaction cleaves the main chain. Furthermore, this transesterification reaction is irreversible because a stable five-membered ring is formed, and it proceeds efficiently (Patent Document 1, Non-Patent Documents 2-5).

[0031] In the copolymer of the present invention, the molar ratio of each repeating unit is not particularly limited, but since the main chain is cleaved in a structure in which CKA and allyl alcohol monomers are bonded in a specific order, the decomposability can be adjusted by the molar ratio of each monomer. Specifically, the closer the composition ratio of repeating units derived from CKA to repeating units derived from allyl alcohol monomers is to equimolar, the more decomposable structures are formed. Therefore, the charging ratio of CKA represented by formula (1) and allyl alcohol monomer represented by formula (2) (molar ratio of (1):(2), totaling 100) is preferably 40:60 to 60:40, more preferably 45:55 to 55:45, even more preferably 47:53 to 53:47, even more preferably 49:51 to 51:49, and most preferably 50:50. Furthermore, the total amount of CKA represented by formula (1) and allyl alcohol-based monomers represented by formula (2) charged to the total monomer (((1)+(2)) / total monomer) is preferably 10 mol% or more and 90 mol% or less, and can be 15 mol% or more, 20 mol% or more, 30 mol% or more, or 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, etc.

[0032] The amount of acrylamide monomer represented by formula (3) added relative to the total monomer can be adjusted according to the desired degradability, hydrophilicity, adhesiveness, etc., of the resulting copolymer. Increasing the amount of acrylamide monomer tends to improve hydrophilicity, thus improving adhesiveness and degradability in water. However, if the amount is too high, the number of degradable structures formed by the polymerization of CKA and allyl alcohol monomer in a specific order decreases. Therefore, the amount of acrylamide monomer represented by formula (3) added relative to the total monomer is preferably 10 mol% to 90 mol%, and can be 20 mol% or more, 30 mol% or more, 40 mol% or more, 50 mol% or more, 60 mol% or more, or 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, etc.

[0033] The number-average molecular weight (Mn) of the copolymer of the present invention is not particularly limited, but if it is too small, the adhesiveness will decrease, so for example, it is preferably 1,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more. The upper limit of the number-average molecular weight (Mn) of the copolymer of the present invention is not particularly limited, but since the viscosity may increase and handling may decrease, for example, it is preferably around 500,000 or less. Furthermore, the molecular weight dispersion (Mw / Mn) of the copolymer of the present invention is not particularly limited, but for example, it is 5.0 or less and 4.5 or less.

[0034] The copolymer of the present invention can be used in disassemblable adhesives, biodegradable paints, resists, etc., because its main chain is rapidly cleaved in an aqueous acetic acid solution, for example. When using the copolymer of the present invention as a disassemblable adhesive, biodegradable paint, resist, etc., the copolymer can be used dissolved in a solvent, or it can be used as a composition containing each monomer and a polymerization initiator. [Examples]

[0035] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0036] <Analytical equipment> (NMR spectrum) Measurement was performed at 25°C using a nuclear magnetic resonance (NMR) spectrometer "AVANCE NEO" (Bruker). Deuterated chloroform was used as the measurement solvent, and tetramethylsilane was used as the internal standard. (Molecular Weight) Two size exclusion columns "SPL-gel, Mixed-C (300 mm × 7.5 mm)" (Agilent) were connected in series to an EXTREMA chromatograph (JASCO Corporation), and the system was heated to 40°C. N,N-dimethylformamide (for high performance liquid chromatography, Wako Pure Chemical Industries) was used as the eluent at a flow rate of 0.8 mL·min -1 , and detection was performed with an ultraviolet absorption spectrometer "UV-4070" (detection at 254 nm, JASCO Corporation) and a differential refractometer (RI-4030, JASCO Corporation). The molecular weight was calibrated with a quintic curve derived from standard polymethyl methacrylate (Tosoh Corporation, TSK gel oligomer kit, MW: 1.03 × 10 6 , 3.89 × 10 5 , 1.82 × 10 5 , 3.68 × 10 4 , 1.36 × 10 4 , 5.32 × 10 3 , 3.03 × 10 3 , 8.73 × 10 2 ). (180° Peel Test) Using a desktop precision universal testing machine AGX-500NX (Shimadzu Corporation), both ends of the adhered test piece were pulled at a displacement rate of 1 mm / min, and the 180° shear stress was measured. The test was performed on two or more specimens, and the average value and standard deviation were calculated.

[0037] <Synthesis of Methyl 2-(trimethylsiloxymethyl)acrylate> 5.00 g, 43.1 mmol of 2-(hydroxymethyl)acrylate was dissolved in 400 mL of dichloromethane, and triethylamine (13.0 mL, 93.4 mmol) was added. Chlorotrimethylsilane (6.00 mL, 47.5 mmol) was added dropwise over 15 minutes at 0°C. The reaction mixture was stirred for 30 minutes, then the ice bath was removed and the mixture was stirred overnight at room temperature. The reaction mixture was diluted with 400 mL of diethyl ether, and the reaction was stopped by adding 375 mL of saturated ammonium chloride aqueous solution. The organic layer was washed twice with saturated brine (375 mL). The organic layer was dried over magnesium sulfate and purified by silica gel column chromatography (eluent: hexane / ethyl acetate = 4 / 1, Rf = 0.65) to obtain 2-(trimethylsiloxymethyl)acrylate as a colorless liquid (4.12 g, 50.7%). 1 The H-NMR spectral data is shown below. 1 H-NMR (400MHz, CDCl3, 25℃) δ / ppm:6.13(dd,J1=1.8Hz,J2=1.9Hz,1H,CHH=),5.76(dd,J1=1.9H z,J2=2.0Hz,1H,CHH=),4.22(t,J=1.9Hz,2H,O-CH2),3.63(s,3H,O-CH3),0.022(s,9H,SiMe3).

[0038] <Synthesis of 5,6-benzo-2-methylene-1,3-dioxepane (CKA29)> [Step 1: Synthesis of 5,6-benzo-2-bromomethyl-1,3-dioxepane] 1,2-Benzene dimethanol (5.00 g, 36.2 mmol) was dissolved with bromoacetaldehyde diethyl acetal (7.87 g, 40.0 mmol) and p-toluenesulfonic acid monohydrate (0.0680 g, 3.60 mmol), and the mixture was refluxed under an argon atmosphere for 1 hour. After cooling, the ethanol was removed by reducing the pressure, and the residue was diluted with chloroform (30 mL) and added dropwise to saturated sodium bicarbonate solution (30 mL) to stop the reaction. The organic layer was washed with distilled water (100 mL), dried over sodium sulfate, and concentrated under reduced pressure. The residue was recrystallized with hexane (49 mL), and vacuum dried to obtain 5,6-benzo-2-bromomethyl-1,3-dioxepane as colorless needle-shaped crystals (yield: 3.09 g, yield: 35.3%). 1 The H-NMR spectral data is shown below. 1 H-NMR (400MHz, CDCl3, 25℃) δ / ppm:7.28-7.22(m,2H,Ar),7.21-7.15(m,2H,Ar),5.12(t,J=5 .1Hz,1H,OCHO),4.93(dd,J1=3.31Hz,J2=14.2Hz,4H,benzyl position),3.45(d,J=5.2Hz,2H,CH2Br).

[0039] [Second step: Synthesis of 5,6-benzo-2-methylene-1,3-dioxepane] 5,6-benzo-2-bromomethyl-1,3-dioxepane (3.09 g, 12.7 mmol) was dissolved in tetrahydrofuran (super-dehydrated grade, 32.9 g, 450 mmol), and potassium tert-butoxide (1.57 g, 14.0 mmol) was added under an argon atmosphere at 0°C and refluxed for 1 hour. After cooling, the reaction mixture was concentrated under reduced pressure, diluted with diethyl ether (20 mL), the precipitate was filtered, the filtrate was concentrated under reduced pressure, and purified by distillation to obtain 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) as colorless needle-shaped crystals (yield: 2.03, yield: 66.8%). 1 The results of the 1H-NMR spectrum are shown below. 1H-NMR (400MHz, CDCl3, 25℃) δ / ppm:7.28-7.20(m,2H,Ar),7.13-7.06(m,2H,Ar),5.06(s,4H,benzyl position),3.72(s,2H,CH2=).

[0040] (Example 1) Synthesis and decomposition of ternary copolymer N-methoxyacrylamide (126 mg, 1.10 mmol), methyl 2-(trimethylsiloxymethyl)acrylate (207 mg, 1.10 mmol), 5,6-benzo-2-methylene-1,3-dioxepane (178 mg, 1.10 mmol), and 2,2′-azobis(isobutyronitrile) (11.1 mg, 66.7 μmol) were mixed, frozen and degassed three times, and then stirred at 65°C for 24 hours. The reaction mixture was dissolved in chloroform (5 mL) and added dropwise to a mixed solvent of hexane (40 mL) and diethyl ether (60 mL) cooled to -100°C. The supernatant was removed by decantation, and the residue was dissolved in chloroform (2 mL) and added dropwise to the mixed solvent of hexane and diethyl ether. This procedure was repeated twice. The residue was vacuum-dried to obtain the copolymer. The number-average molecular weight Mn was 13400, the weight-average molecular weight Mw was 54000, and the molecular weight dispersion Mw / Mn was 4.01, as evaluated by size exclusion chromatography.

[0041] The obtained copolymer was dispersed in a 50% by mass aqueous solution of acetic acid and stirred at room temperature (20-25°C). Small samples were taken at 5 minutes, 30 minutes, and 60 minutes, neutralized with saturated aqueous sodium bicarbonate solution, and extracted with chloroform. The organic layer was concentrated, vacuum-dried, and the residue was analyzed by size exclusion chromatography. Figure 1 shows the size exclusion chromatograms at each time point, normalized to match peak top heights. The peak top molecular weight (Mp) changed from 61100 before the reaction to 19100 after 5 minutes and to 5830 after 30 minutes. After 60 minutes, the amount of sample extracted with chloroform was small, resulting in a very weak signal. Subsequently, no signal was detected by size exclusion chromatography even with chloroform extraction. Furthermore, the residue after 24 hours readily dissolved in pure water.

[0042] The above results indicate that the polymer obtained in Example 1 undergoes main chain cleavage by aqueous acetic acid solution. In particular, a significant decrease in molecular weight was observed after 5 minutes compared to the initial value, and after 30 minutes, the peak top molecular weight was an order of magnitude smaller than the initial value. On the other hand, Non-Patent Document 5 discloses the decomposition behavior of a binary copolymer obtained by polymerization of an equimolar mixture of methyl 2-(trimethylsiloxymethyl)acrylate and 5,6-benzo-2-methylene-1,3-dioxepane. When a decomposition test of the binary copolymer was performed using the same procedure as in Example 1, the peak top molecular weight Mp in the size exclusion chromatogram was 19,700 after 3 hours compared to 24,000 before the reaction, and only decreased to 3,510 after 4 hours.

[0043] The main chain scaling of the copolymers described in the present invention and Non-Patent Document 5 is based on an intramolecular transesterification reaction in the chain formed when CKA (5,6-benzo-2-methylene-1,3-dioxepane) and an allyl alcohol monomer (2-(trimethylsiloxymethyl)methyl acrylate) are polymerized in a specific order. Compared to the binary copolymer described in Non-Patent Document 5, the ternary copolymer of Example 1 was expected to be less prone to main chain scaling due to its lower content of CKA and allyl alcohol monomer. However, in reality, the ternary copolymer of Example 1 underwent a rapid decrease in molecular weight compared to the binary copolymer described in Non-Patent Document 5. This confirmed that copolymerizing with an acrylamide monomer (N-methoxyacrylamide) significantly improved the decomposition rate.

[0044] (Example 2) Bonding by ternary copolymerization A polymerization composition was prepared by mixing N-methoxyacrylamide (0.368 g, 3.20 mmol), methyl 2-(trimethylsiloxymethyl)acrylate (0.075 g, 0.40 mmol), 5,6-benzo-2-methylene-1,3-dioxepane (0.064 g, 0.40 mmol), and 2,2-dimethoxy-2-phenylacetophenone (20 mg, 80 μmol), and performing freeze-degassing three times. For a polyethylene terephthalate substrate with a width of 1 cm, the adhesive area is 1.0 cm². 2 The polymerization composition was applied in this manner, and another polyethylene terephthalate substrate was placed on top. When 365 nm ultraviolet light was irradiated at an intensity of 50 mW for 1 hour using a photoreaction LED light source (Asahi Spectroscopy, CL-H1-365-9-1-B), the polyethylene terephthalate substrate was successfully bonded.

[0045] (Example 3) Bonding and decomposition by ternary copolymerization The procedure was the same as in Example 2, except that a polymerization composition prepared from N-methoxyacrylamide (0.092 g, 0.80 mmol), 2-(trimethylsiloxymethyl)methyl acrylate (0.150 g, 0.80 mmol), 5,6-benzo-2-methylene-1,3-dioxepane (0.129 g, 0.80 mmol), and 2,2-dimethoxy-2-phenylacetophenone (12 mg, 48 μmol) was used to obtain bonded test pieces.

[0046] The peel force measured by the 180° peel test of the test specimen was an average of 62 ± 5.4 N / 25 mm. After immersing the test specimen in 70°C pure water for 30 minutes, a 180° peel test was performed, and the average peel force was 64±5.2 N / 25 mm. Since there was no difference in the peel force from the initial value, the water resistance of the adhesive to hot water was confirmed. On the other hand, after immersing the test specimen in a 50% by mass aqueous acetic acid solution at 70°C for 30 minutes, the peeling force decreased to an average of 41±2.2 N / 25 mm, confirming that the adhesive was decomposed by the aqueous acetic acid solution.

[0047] (Example 4) Bonding and decomposition by ternary copolymerization Test specimens were obtained in the same manner as in Example 3, except that the target of bonding was a glass substrate with a width of 1 cm. The adhesive strengths when the ultraviolet light irradiation time was 10 minutes, 30 minutes, and 3 hours were 127±63 N / 25 mm, 164±95 N / 25 mm, and 164±6.1 N / 25 mm, respectively. Figure 2 shows a photograph of a test specimen prepared after being irradiated with ultraviolet light for 10 minutes, and then immersed in water or an aqueous acetic acid solution. When immersed in 30°C pure water for 24 hours, no delamination occurred. On the other hand, when immersed in a 50 mass percent acetic acid aqueous solution at 30°C, the test specimen spontaneously delaminated after 3.5 hours. The adhesive layer decomposed and dissolved over time, and almost no adhesive residue was observed at the time of delamination. Furthermore, when a similarly prepared test specimen was immersed in 80°C pure water, the adhesive layer softened and spontaneous delamination was observed after 14 minutes, but a clear adhesive residue was observed. When immersed in a 50 mass percent acetic acid aqueous solution at 80°C, spontaneous delamination was observed after 2 minutes, and almost no adhesive residue was observed.

[0048] (Reference Example 1) Study of adhesion by binary copolymerization The procedure was carried out in the same manner as in Example 2, except that a polymerization composition was used, which consisted of methyl 2-(trimethylsiloxymethyl)acrylate (0.113 g, 0.600 mmol), 5,6-benzo-2-methylene-1,3-dioxepane (0.097 g, 0.60 mmol), and 2,2-dimethoxy-2-phenylacetophenone (6.2 mg, 24 μmol), and the substrate to be bonded was a glass substrate with a width of 1 cm. Even after irradiating with ultraviolet light for up to 4 hours, the glass substrate could not be bonded.

[0049] A comparison of Example 4 and Reference Example 1 demonstrated that the acrylamide monomer (N-methoxyacrylamide) is essential for achieving adhesion between glass substrates. Furthermore, it was shown that the UV-curable adhesive shown in Example 3 decomposes and dissolves in an aqueous acetic acid solution, resulting in peeling without leaving any adhesive residue.

[0050] (Example 5) Bonding and decomposition by ternary copolymerization A polymerized composition was prepared by mixing N-methoxyacrylamide (0.011 g, 0.10 mmol), methyl 2-(trimethylsiloxymethyl)acrylate (0.084 g, 0.45 mmol), 5,6-benzo-2-methylene-1,3-dioxepane (0.073 g, 0.45 mmol), and 2,2-dimethoxy-2-phenylacetophenone (5.1 mg, 20 μmol). A bonded test piece was obtained in the same manner as in Example 2, except that the bonded object was a glass substrate with a width of 1 cm and the ultraviolet light irradiation time was 30 minutes. went. When the bonded test specimens were immersed in a 50% by mass aqueous solution of acetic acid heated to 80°C, they spontaneously peeled off in 10 seconds. When the peeled bonded surface was immersed for another minute, the adhesive layer dissolved, and the glass substrate was recovered without any adhesive residue (Figure 3).

[0051] (Example 6) Adhesion and decomposition by quaternary copolymerization A polymerized composition was prepared by mixing acrylamide (0.028 g, 0.40 mmol), N-methoxyacrylamide (0.100 g, 0.870 mmol), methyl 2-(trimethylsiloxymethyl)acrylate (0.075 g, 0.40 mmol), 5,6-benzo-2-methylene-1,3-dioxepane (0.064 g, 0.40 mmol), and 2,2-dimethoxy-2-phenylacetophenone (85 mg, 33 μmol). A bonded test piece was obtained in the same manner as in Example 2, except that the bonded object was a glass substrate with a width of 1 cm and the ultraviolet light irradiation time was 30 minutes. When the bonded test pieces were immersed in a 50 mass percent acetic acid aqueous solution heated to 80°C, they naturally separated after 50 minutes, and the glass substrate was recovered without any adhesive residue (Figure 4).

Claims

1. A repeating unit derived from a cyclic ketene acetal monomer represented by the following formula (1), 【Chemistry 1】 (In the formula, ring A is a 5- to 7-membered ring that may have substituents, and the substituents may form fused rings.) A repeating unit derived from an allyl alcohol monomer represented by the following formula (2), 【Chemistry 2】 (In the formula, R is C １ -C ６ Alkyl alkyl group, C １ -C ６ This represents a haloalkyl group, a phenyl group, or a substituted phenyl group. (W represents a hydrogen atom or a trialkylsilyl group.) A repeating unit derived from an acrylamide monomer represented by the following formula (3), 【Transformation 3】 (In the formula, R ５ This represents a hydrogen atom or a methyl group. R ６ represents a hydrogen atom, C １ -C ６ alkyl group (non-consecutive -CH ２ - may be replaced by -O-), or C １ -C ６ haloalkyl group (non-consecutive -CH ２ - may be replaced by -O-).) A copolymer characterized by having the following properties.

2. A disassemblable adhesive characterized by containing the copolymer described in claim 1.

3. A cyclic ketene acetal monomer represented by the following formula (1), 【Chemistry 4】 (In the formula, ring A is a 5- to 7-membered ring that may have substituents, and the substituents may form fused rings.) An allyl alcohol monomer represented by the following formula (2), 【Transformation 5】 (In the formula, R is C １ -C ６ Alkyl alkyl group, C １ -C ６ This represents a haloalkyl group, a phenyl group, or a substituted phenyl group. (W represents a hydrogen atom or a trialkylsilyl group.) Acrylamide monomer represented by the following formula (3), 【Transformation 6】 (In the formula, R ５ This represents a hydrogen atom or a methyl group. R ６ C is a hydrogen atom. １ -C ６ Alkyl group (non-consecutive -CH) ２ (- may be replaced with -O-), or C １ -C ６ Haloalkyl groups (non-consecutive -CH) ２ This indicates that - can be replaced with -O-. A decomposable adhesive composition characterized by containing a polymerization initiator.

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