JP2019026817A - Photoresponsive adhesive - Google Patents

Abstract

To provide a photoresponsive adhesive which has pressure-sensitive adhesiveness when fluidized by light irradiation and recovers adhesive force when cured again by light irradiation with a different wavelength.SOLUTION: The photoresponsive adhesive comprises as an active ingredient a liquid crystal polymer represented by the general formula (1) in the figure, where l is an integer from 1 to 20, m is an integer from 1 to 20, n is from 2 to 200, Ris H or a methyl group, Ris S, O, secondary or tertiary N, or an ester group.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a photoresponsive adhesive which can be reversibly softened and solidified with light to control an adhesive state and an adhesive state and to repeat this.

  As a method for reversibly fluidizing and de-fluidizing a material by light irradiation, a method of irradiating a liquid crystalline azobenzene compound having a sugar alcohol skeleton (see Patent Document 1) with ultraviolet light and visible light is known (patent). Document 2, Non-Patent Document 1, and Non-Patent Document 2). The fluidization-non-fluidization of this liquid crystalline azobenzene compound is based on the fact that an azobenzene structure having photoresponsiveness undergoes phase transition by light irradiation.

  FIG. 1 is a photograph showing fluidization-non-fluidization of a liquid crystalline azobenzene compound by this method. As shown in FIG. 1, when a solid powdery azobenzene compound (image left) is irradiated with ultraviolet light, the compound is liquefied into spherical droplets (image center). When this liquid is irradiated with visible light, it becomes a solid that maintains a spherical shape even when lifted with a spoon (right image). When this solid material is irradiated again with ultraviolet light, it returns to a spherical droplet (center of the image).

  As an application of such a reversibly fluidized-non-fluidized compound, an adhesive that can be reversibly adhered and peeled by light irradiation has been proposed. With a general adhesive, it is difficult to peel the adherend without applying heat or mechanical shock after the adherend is once bonded to the substrate. In addition, it was difficult to use the remaining adhesive for re-adhesion after the adherend was peeled off. These problems can be solved by using a material that can be repeatedly bonded and peeled reversibly with light.

  In addition, the azobenzene polymer compound, which is a polymer having an azobenzene structure in the side chain, is reversibly fluidized and non-flowed by light irradiation in the same manner as the low-molecular azobenzene compound described in Patent Document 1 and the like. It is known that the adhesive force at the time of bonding is further increased while maintaining the property to be converted (Patent Document 3 and Non-Patent Document 3). In addition, a composition comprising a polymer compound, a liquid crystal compound, and a photoresponsive compound has been reported as a material that is reversibly softened and solidified by light irradiation (Patent Document 4). When this composition is irradiated with ultraviolet light, the molecular shape of the photoresponsive compound changes and the composition softens. When the softened composition is further irradiated with visible light, the composition is cured again. A photoresponsive adhesive which utilizes this phenomenon has been proposed.

Japanese Patent No. 5360794 Japanese Patent No. 5561728 International Publication No. WO2013 / 168712 International Publication No. WO2016 / 121651

Advanced. Materials, 24, 2353-2356 (2012) ACS Appl. Mater. Interfaces, 6, 7933-7941 (2014) J. Adhesion in press. (DOI: 10.1080 / 00218464.2016.1219255)

  The photoresponsive compounds described in Patent Literature 1 to Patent Literature 3 have no adhesive force when liquefied by light irradiation and peeled off. For this reason, this photoresponsive compound cannot hold | maintain an adherend just before peeling. In adhering, it is necessary to fix the adherend until the liquid photoresponsive compound is irradiated with light to develop an adhesive force. For this reason, there exists a fault in workability | operativity when adhere | attaching a to-be-adhered body to a base material.

  The photoresponsive compound described in Patent Document 4 does not have the above-mentioned disadvantage because it exhibits adhesiveness when softened by ultraviolet light irradiation. However, since the adhesive strength is not restored at the time of recuring, it cannot be repeatedly used as a photoresponsive adhesive. The present invention provides a photoresponsive adhesive that improves such drawbacks of conventional photoresponsive compounds, exhibits tackiness when fluidized by light irradiation, and further restores adhesive strength when re-cured. This is the issue.

  As a result of intensive studies to achieve the above object, the present inventors have found that a polymer liquid crystal containing a photoresponsive group as a site exhibiting a photo phase transition and a hydrogen bonding functional group for increasing cohesive force. It has been found that a photoresponsive adhesive which can control the adhesive state and the adhesive state can be obtained by reversibly softening and solidifying by light irradiation using a photosensitive compound, and the present invention has been completed. The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.

  The liquid crystal polymer compound of the present invention is represented by the following general formula (1).

ただし、式中、ｌは１〜２０の整数、ｍは１〜２０の整数、ｎは２〜２００であり、Ｒ₁はＨまたはメチル基であり、Ｒ₂は、Ｓ、Ｏ、２級もしくは３級のＮ、またはエステル基である。

In the formula, l is an integer of 1 to 20, m is an integer of 1 to 20, n is 2 to 200, R ₁ is H or a methyl group, and R ₂ is S, O, secondary or Tertiary N or an ester group.

  The method for producing a liquid crystal polymer compound of the present invention comprises a poly (glycidyl methacrylate) represented by the following general formula (2) and a mercaptan, an alcohol, 1 an azobenzene represented by the following general formula (3), Reaction with a secondary or secondary amine or carboxylic acid.

ただし、式中、ｌ、ｍ、ｎ、およびＲ₁は上記の一般式(１)と同じであり、Ｒ₃は、メルカプト基、ヒドロキシ基、１級もしくは２級アミノ基、またはカルボキシ基である。

In the formula, l, m, n, and R ₁ are the same as those in the general formula (1), and R ₃ is a mercapto group, a hydroxy group, a primary or secondary amino group, or a carboxy group. .

  The photoresponsive adhesive of the present invention contains the liquid crystal polymer compound of the present invention as an active ingredient. The method for peeling an adherend according to the present invention includes an ultraviolet light having a wavelength of 300 to 400 nm applied to the photoresponsive adhesive with the adherend adhered to the substrate via the photoresponsive adhesive of the present invention. Irradiate light to make it sticky and peel the adherend from the substrate. The adhesion method of the adherend of the present invention is such that the adherend is adhered to the substrate via the photoresponsive adhesive of the present invention, and the visible light having a wavelength of 420 to 600 nm is applied to the photoresponsive adhesive. Light is irradiated to form a solid state, and the adherend is bonded to the substrate.

  The photoresponsive adhesive of the present invention exhibits tackiness when irradiated with light. For this reason, it is excellent in workability | operativity when adhering an adherend to a base material through the photoresponsive adhesive agent of this invention, or peeling an adherend from a base material.

A photograph showing a liquid crystalline azobenzene compound in a fluidized state and a non-fluidized state by light irradiation. ¹ H NMR spectrum of the liquid crystal polymer compound obtained in Production Example 3. The figure which shows the adhesive strength test using the liquid crystal polymer compound obtained by manufacture example 3. FIG.

  The liquid crystal polymer compound according to the embodiment of the present invention is represented by the following general formula (1).

ただし、式中、ｌは１〜２０の整数、ｍは１〜２０の整数、ｎは２〜２００であり、Ｒ₁はＨ(水素原子)またはメチル基であり、Ｒ₂は、Ｓ(硫黄原子)、Ｏ(酸素原子)、２級もしくは３級のＮ(窒素原子)、またはエステル基(ＯＣＯもしくはＣＯＯ)である。なお、本願では、２つの数値の間に「〜」を入れて数値範囲を表わす場合は、これらの２つの数値が含まれる。

In the formula, l is an integer of 1 to 20, m is an integer of 1 to 20, n is 2 to 200, R ₁ is H (hydrogen atom) or a methyl group, and R ₂ is S (sulfur). Atom), O (oxygen atom), secondary or tertiary N (nitrogen atom), or ester group (OCO or COO). In the present application, when a numerical range is expressed by putting “˜” between two numerical values, these two numerical values are included.

  The liquid crystal polymer compound of this embodiment is a side chain type liquid crystal polymer compound containing azobenzene and having two or more photoresponsive side chains. That is, the liquid crystal polymer compound of this embodiment includes a photoresponsive group that induces a phase transition by light irradiation. In addition, the liquid crystal polymer compound of the present embodiment has a hydrogen-bonding hydroxy group that imparts tackiness by increasing the intermolecular force. For this reason, unlike the conventional photoresponsive polymer compound, the liquid crystal polymer compound of the present embodiment does not completely liquefy when softened and exhibits adhesiveness. That is, the liquid crystal polymer compound of the present embodiment exhibits an initial adhesive force when the adherend is bonded to the substrate. Therefore, if the liquid crystal polymer compound of this embodiment is used as an adhesive, the workability at the time of adhesion of the adherend is improved. The liquid crystal polymer compound of this embodiment can be reversibly softened and solidified by light irradiation, and can adhere and peel off the adherend reversibly.

  The liquid crystal polymer compound of the present embodiment is solid at normal temperature and has no fluidity at the time of bonding. However, the liquid crystal polymer compound is softened by irradiation with light having a predetermined wavelength, and adhesive strength is reduced and adhesiveness is exhibited. Further, when the softened liquid crystal polymer compound of the present embodiment is irradiated with light of another predetermined wavelength, the liquid crystal polymer compound is solidified and the adhesive force is recovered. That is, the liquid crystal polymer compound of the present embodiment can be softened and solidified reversibly by selecting and irradiating light with a suitable wavelength. In the liquid crystal polymer compound of this embodiment, the azobenzene structure present in the side chain is photoisomerized as shown below according to the light irradiated.

  In order to soften the liquid crystal polymer compound of this embodiment, it is necessary to isomerize azobenzene from a trans isomer to a cis isomer. In order to increase the isomerization rate, it is preferable to irradiate light having a wavelength that is not absorbed by the cis isomer. When the liquid crystal polymer compound of this embodiment is irradiated with ultraviolet light having a wavelength of 300 to 400 nm, which is the main absorption region of the transformer, it softens. That is, the liquid crystal polymer compound of this embodiment is softened and exhibits adhesiveness when irradiated with ultraviolet light having a wavelength of 300 to 400 nm, for example. However, in order to soften more efficiently, it is preferable to irradiate ultraviolet light having a wavelength of 350 to 390 nm, and it is more preferable to irradiate ultraviolet light having a wavelength of around 365 nm.

On the other hand, in order to solidify the liquid crystal polymer compound of the present embodiment, it is preferable to irradiate visible light having a wavelength of 420 to 600 nm, and more preferably to irradiate visible light having a wavelength of around 500 nm. By this light irradiation, the liquid crystal polymer compound of this embodiment is isomerized from the cis form to the trans form. That is, the liquid crystal polymer compound of this embodiment is solidified when irradiated with visible light having a wavelength of 420 to 600 nm, for example. In addition, the optimal wavelength of the light irradiated to the liquid crystal polymer compound of the present embodiment varies depending on the molecular structure around the azobenzene structure. The amount of exposure when the liquid crystal polymer compound of this embodiment is irradiated with light varies depending on the type of light source and the thickness of the adhesive, but is preferably 0.1 to 200 J / cm ² , and preferably 0.5 to 100 J / cm ^2. cm ² is more preferred.

  The liquid crystal polymer compound of this embodiment can reversibly control softening and solidification by irradiation with light having different wavelengths. The liquid crystal polymer compound of this embodiment has a photoisomerizable azobenzene structure in the side chain, and can be photoisomerized even in a solidified state. In the liquid crystal polymer compound of the present embodiment, the molecular structure is largely changed by the photoisomerization reaction in a solidified state, and is softened and transitions to a state showing adhesiveness. By irradiating the liquid crystal polymer compound of the present embodiment in an adhesive state with light having a different wavelength, or simply leaving the liquid crystal polymer compound of the present embodiment in an adhesive state, a reverse reaction occurs. Solidify again. In the liquid crystal polymer compound of this embodiment, such softening / solidification operations can be repeated.

  The liquid crystal polymer compound of the present embodiment is a solid under a temperature around room temperature and in a normal light irradiation environment. Therefore, when using the liquid crystal polymer compound of the present embodiment as an adhesive, after sandwiching between the substrate and the adherend in a state of being softened by irradiating the liquid crystal polymer compound of the present embodiment with ultraviolet light, Visible light is irradiated and solidified to adhere the adherend to the substrate. Further, the liquid crystal polymer compound of the present embodiment can be heated and melted and sandwiched between the substrate and the adherend, and then cooled and solidified to be bonded.

  Further, the liquid crystal polymer compound of the present embodiment, which has been processed into a sheet shape or a tape shape in advance, is sandwiched between the base material and the adherend, and then solidified after being softened by light irradiation, heating or cooling, and the adherend is then used as a base. It may be adhered to the material. Further, the liquid crystal polymer compound of the present embodiment dissolved in a solvent is applied to the surface of the adherend and dried, then the adhesive is softened and attached to the base material, and the adhesive is solidified to make the adherend the base material. It can also be adhered to. When the liquid crystal polymer compound of the present embodiment is softened by heating, the liquid crystal polymer compound is heated to a melting point, a glass transition point, or a temperature equal to or higher than the softening point (for example, 90 ° C. or higher) depending on the molecular weight or chemical structure.

  When the photoresponsive polymer compound described in Patent Document 2, Non-Patent Document 1, and Non-Patent Document 2 is liquefied by irradiation with ultraviolet light, the adhesive force is completely lost and the adherend cannot be held. . This is because most of the photoresponsive polymer compound is composed of a non-polar long alkyl chain, has a weak intermolecular force, and does not exhibit adhesiveness. In view of this, the liquid crystal polymer compound of this embodiment in which a hydroxy group that is a polar functional group and an azobenzene moiety that induces a photo phase transition are chemically bonded was designed. Like the liquid crystal polymer compound of this embodiment, by introducing a polar functional group to increase the intermolecular force, it exhibits adhesiveness when softened by ultraviolet light irradiation. For this reason, if the liquid crystal polymer compound of this embodiment is used as an adhesive, the adherend can be held, and the workability of the adhesion / peeling operation is improved.

  Since the liquid crystal polymer compound of the present embodiment has a polar hydroxy group in the repeating unit, the intermolecular force is improved, and exhibits adhesiveness when softened by irradiation with ultraviolet light. In addition, the viscosity increases as the molecular weight of the polymer compound increases. In order to show adhesiveness when softened, the number average molecular weight of the liquid crystal polymer compound of this embodiment is preferably 1000 to 100,000.

  A method for producing a liquid crystal polymer compound according to an embodiment of the present invention includes a mercaptan containing poly (glycidyl methacrylate) represented by the following general formula (2) and azobenzene represented by the following general formula (3). , Alcohol, primary or secondary amine, or carboxylic acid.

ただし、式中、ｌ、ｍ、ｎ、およびＲ₁は上記の一般式(１)と同じであり、Ｒ₃は、メルカプト基、ヒドロキシ基、１級もしくは２級アミノ基、またはカルボキシ基である。

In the formula, l, m, n, and R ₁ are the same as those in the general formula (1), and R ₃ is a mercapto group, a hydroxy group, a primary or secondary amino group, or a carboxy group. .

  Although this reaction can be carried out in the absence of a catalyst, it is preferably carried out using a suitable catalyst. Specifically, a catalyst that works as a base for extracting active hydrogen of the compound of the general formula (3) and promotes a nucleophilic addition reaction to an epoxy group is preferable. Such catalysts include tertiary amines such as triethylamine, alkali metal hydroxides such as lithium hydroxide, alkali metal hydrides such as sodium hydride, alkali metals such as lithium, and quaternary compounds such as tetrabutylammonium fluoride. An ammonium salt etc. are mentioned.

  In addition, this reaction is preferably performed in a suitable solvent. Preferred examples of the solvent include ethers such as tetrahydrofuran and aprotic polar solvents such as dimethylformamide and dimethyl sulfoxide. These solvents may be used alone or in combination with other solvents. About 1-100 mL is preferable with respect to 1 g of mass of all the raw materials, and, as for the usage-amount of a solvent, about 5-50 mL is more preferable.

  The reaction temperature is not particularly limited but is preferably from 0 ° C. to the boiling point of the solvent. Also, the reaction pressure is not particularly limited, and any of normal pressure, pressurization, and reduced pressure may be used. This reaction time is usually 1 to 24 hours. The compound obtained by this reaction can be used without purification by distilling off the solvent, but conventional methods such as reprecipitation into a non-solvent, column chromatography, high performance liquid chromatography, dialysis using a semipermeable membrane, etc. You may refine | purify and use.

  As a synthesis method of the compound of the general formula (2), an anionic polymerization method (Hild, G., Polymer 1993, 34, 2875-2882. Etc.) and a radical polymerization method (Krishnan, R., Macromolecules 2003, 36, 1769). -1771 etc.) is known. An example of a simpler synthesis method by radical polymerization is a method of polymerizing a monomer represented by the following general formula (5) in the presence of a copper catalyst using a compound represented by the following general formula (4) as an initiator. it can.

In the formula, R ₁ is H (hydrogen atom) or a methyl group, R ₄ is a methyl group or an ethyl group, and R ₅ is Cl (chlorine atom) or Br (bromine atom).

  The photoresponsive adhesive according to the embodiment of the present invention includes the liquid crystal polymer compound of the present embodiment as an active ingredient. In the photo-responsive adhesive of the present embodiment, in addition to the active ingredient, a solvent such as acetone, a tackifier such as a terpene resin, and a liquid petroleum-derived resin are diluted within a range that does not impair the object of the present invention. Agents, fillers or extenders such as calcium carbonate and silica, thickeners such as methylcellulose and vinyl alcohol, plasticizers such as adipates, pigments such as titanium oxide, flame retardants such as aluminum hydroxide, phosphines, etc. An antioxidant or the like may be contained.

  The method for peeling the adherend according to the embodiment of the present invention has a wavelength applied to the photoresponsive adhesive with the adherend adhered to the substrate via the photoresponsive adhesive of the present embodiment. 300 to 400 nm of ultraviolet light is irradiated to make it adhere, and the adherend is peeled off from the substrate. Further, the adhesion method of the adherend according to the embodiment of the present invention is a photoresponsive adhesive with the adherend being adhered to the substrate via the photoresponsive adhesive of the present embodiment. The substrate is irradiated with visible light having a wavelength of 420 to 600 nm to form a solid state, and the adherend is bonded to the substrate.

  Since adhesion and peeling are performed by light irradiation, it is possible to select an adherend that allows light of a predetermined wavelength to reach the photoresponsive adhesive of the present embodiment existing between the adherend and the substrate. preferable. Examples of such an adherend include glass, PET, polycarbonate, and a polystyrene plate. However, the adherend need not be colorless. Moreover, the light transmittance of a base material is not required. Examples of the substrate include aluminum, iron, colored glass, and earthenware.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to this Example.

Production Example 1: Synthesis of poly (glycidyl methacrylate) Poly (glycidyl methacrylate) was synthesized according to the method described in the paper (Macromolecules 36, 1769-1771 (2003)) as shown in the following chemical reaction formula. .

  A mixture of 5 g of glycidyl methacrylate, 11.6 mg of copper (I) chloride, N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine 20.4 mg, and 4.7 mL of diphenyl ether was frozen and degassed. 458 mg of ethyl bromoisobutyrate was added and polymerized at 30 ° C. for 4 hours. The polymer was purified by alumina column treatment and reprecipitation into methanol to obtain 2.58 g of a white solid (yield 54%). Mn, NMR = 6240, Mw / Mn = 1.20.

Production Example 2: Synthesis of 10- (4- (4-hexylphenylazo) phenoxy) decanethiol As shown in the following chemical reaction formula, a paper (J. Phys. Chem. B 105, 2255-2260 (2002)) 10- (4- (4-hexylphenylazo) phenoxy) decanethiol was synthesized according to the method described in 1).

  A mixture of 9.40 g of 4-hexyl-4'-hydroxyazobenzene, 50 g of 1,10-dibromodecane, 10.0 g of potassium carbonate, 0.50 g of potassium iodide, and 300 mL of acetone was refluxed for 16 hours. After adding 600 mL of water and filtering, it was washed with 100 mL of water and 50 mL of ethanol, and dried under reduced pressure. It was dissolved in a mixed solvent of 100 mL of heated chloroform and 40 mL of methanol and recrystallized to obtain 9.14 g of a yellow solid (yield 54%).

  A mixture of the obtained substance (3.07 g), thiourea (0.70 g), and degassed ethanol (200 mL) was refluxed for 18 hours, and then the ethanol was distilled off under reduced pressure. It was dissolved again in 200 mL of degassed ethanol, an aqueous sodium hydroxide solution (0.43 g / 5 mL) was added, and the mixture was refluxed for 6 hours. After neutralizing with 1 mL of concentrated hydrochloric acid and concentrating, it was dissolved in ether, washed with water, and the solvent was distilled off to obtain 1.63 g of a yellow solid (yield 58%).

Production Example 3: Synthesis of poly (methacrylic acid 3- (4- (4-hexylphenylazo) phenoxydecylthio) -2-hydroxypropyl) As shown in the following chemical reaction formula, a liquid crystal polymer compound poly (methacrylic acid) 3- (4- (4-Hexylphenylazo) phenoxydecylthio) -2-hydroxypropyl) was synthesized.

  94 mg of poly (glycidyl methacrylate) obtained in Production Example 1, 0.63 g of 10- (4- (4-hexylphenylazo) phenoxy) decanethiol obtained in Production Example 2, 14 mg of lithium hydroxide monohydrate , Tetrahydrofuran (6.0 mL), and water (75 μL) were degassed and stirred at room temperature for 18 hours. After reprecipitation in a mixed solvent of methanol / water (volume ratio 95/5), the mixture was purified by preparative column chromatography to obtain 0.32 g of a yellow solid (yield 78%). Mn, GPC-LS = 28100 (n = 45.2), Mw / Mn = 1.09. The structure of the obtained liquid crystalline polymer compound was confirmed by nuclear magnetic resonance spectroscopy (manufactured by JEOL RESONANCE, JNM-ECS400, deuterated chloroform solvent). The result is shown in FIG.

Example 1
The liquid crystal polymer compound obtained in Production Example 3 is placed on a very small amount of glass substrate, and an ultraviolet light having a center wavelength of about 365 nm is used at room temperature (about 25 ° C.) using an LED light source (CLV HLV-24UV365-4WNRBTNJ). Irradiated for 5 minutes (15 J / cm ² ). The polymer compound changed from a yellow powdery polymer to an orange sticky polymer.

Example 2
When the differential scanning calorimetry of the liquid crystal polymer compound obtained in Production Example 3 (Pyris manufactured by PerkinElmer, temperature drop at 10 K / min) is performed, the isotropic phase-liquid crystal phase transition is 130 ° C., and the liquid crystal-liquid crystal phase transition is 119. The glass transition temperature was 86 ° C. On the other hand, the glass transition temperature of the liquid crystal polymer compound obtained in Example 1 after irradiation with ultraviolet light was −20 ° C., and this liquid crystal polymer compound was a fluid exhibiting adhesiveness at room temperature.

Example 3
About 1 mg of the liquid crystal polymer compound obtained in Production Example 3 that was not irradiated with ultraviolet light was placed on a glass substrate, heated and melted, and then sandwiched between other glass substrates to expand to a size of 15 mm × 5 mm. When this was cooled, the glass substrate was bonded. Even when these two glass substrates were pulled in the opposite direction, they did not peel off. Peeling occurred when a force of 260 N / cm ² (average value measured five times) was mechanically applied in the tensile strength test. The state of the adhesive strength test is shown in FIG.

Example 4
A liquid crystal polymer compound sandwiched between two glass substrates produced in the same manner as in Example 3 was irradiated with ultraviolet light having a center wavelength of about 365 nm for 5 minutes at room temperature (about 25 ° C.) using an LED light source (15 J / Cm ² ). The adhesive surface softened and changed from yellow to orange. Peeling occurred when a force of 123 N / cm ² (average value measured five times) was mechanically applied in the tensile strength test.

Example 5
In the same manner as in Example 4, the liquid crystal polymer compound sandwiched between two glass substrates was irradiated with ultraviolet light. Furthermore, using a LED light source (CLV HLV2-22GR-3W), the liquid crystal polymer compound was irradiated with visible light having a central wavelength of about 520 nm (12 J / cm ² ). The adhesive surface solidified and changed from orange to yellow. The film was peeled when a force of 352 N / cm ² (average value measured five times) was mechanically applied in the tensile strength test. From the results of Examples 3 to 5, it was found that the adhesive strength was restored when the liquid crystal polymer compound obtained in Production Example 3 was softened and then solidified.

Example 6
In the same manner as in Production Examples 1 to 3, four types of liquid crystal polymer compounds having different molecular weights were produced. The polymerization degree n of the raw material poly (glycidyl methacrylate) was 15, 27, 43, and 60, respectively, as a result of ¹ H NMR analysis. The various liquid crystal polymer compounds obtained were subjected to a tensile strength test in the same manner as in Examples 3 to 5. The test force when peeled was measured five times. Table 1 shows the relationship between the number average molecular weight of the liquid crystal polymer compound and the average peel strength.

  As shown in Table 1, regardless of the difference in the number average molecular weight, when the liquid crystal polymer compound is irradiated with ultraviolet light, the peel strength is lowered to exhibit adhesiveness, and the liquid crystal polymer exhibits adhesiveness by ultraviolet light irradiation. When the compound was irradiated with visible light, it solidified and the peel strength was improved. Moreover, it turned out that a liquid crystal polymer compound has adhesive force also by cooling after heat-melting.

Claims (8)

A liquid crystal polymer compound represented by the following general formula (1).

In the formula, l is an integer of 1 to 20, m is an integer of 1 to 20, n is 2 to 200, R ₁ is H or a methyl group, and R ₂ is S, O, secondary or Tertiary N or an ester group. _2. The liquid crystal polymer compound according to claim 1, wherein l is 10, m is 6, R ₁ is a methyl group, and R ₂ is S.   The liquid crystal polymer compound according to claim 1 or 2, which exhibits tackiness when irradiated with ultraviolet light having a wavelength of 300 to 400 nm.   The liquid crystal polymer compound according to any one of claims 1 to 3, which solidifies when irradiated with visible light having a wavelength of 420 to 600 nm in an adhesive state.   The photoresponsive adhesive which uses the liquid crystal polymer compound in any one of Claim 1 to 4 as an active ingredient. Reaction of poly (glycidyl methacrylate) represented by the following general formula (2) with mercaptan, alcohol, primary or secondary amine or carboxylic acid containing azobenzene represented by the following general formula (3) A method for producing a liquid crystal polymer compound.

In the formula, l, m, n, and R ₁ are the same as those in the general formula (1), and R ₃ is a mercapto group, a hydroxy group, a primary or secondary amino group, or a carboxy group. .   In the state where the adherend is adhered to the base material via the photoresponsive adhesive of claim 5, the photoresponsive adhesive is irradiated with ultraviolet light having a wavelength of 300 to 400 nm to adhere to the substrate. A method for peeling the adherend, wherein the adherend is peeled from the substrate.   In a state where the adherend is adhered to the substrate via the photoresponsive adhesive of claim 5, the photoresponsive adhesive is irradiated with visible light having a wavelength of 420 to 600 nm to form a solid. A method for bonding an adherend, wherein the adherend is bonded to the substrate.

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