Temperature-sensitive adhesive and processing method for workpieces

Abstract

To provide a temperature-sensitive tacky adhesive excellent in fixability and easy detachability, and a processing method for a workpiece.SOLUTION: A temperature-sensitive tacky adhesive in the present invention is a reaction product of a compound having an ultraviolet-curable functional group and a side-chain crystalline polymer, and includes an ultraviolet curable side-chain crystalline polymer indicating flowability at temperatures higher than its melting point. The side-chain crystalline polymer includes (meth)acrylate having 16C or more straight chain alkyl group, (meth)acrylate having 2-6C alkyl group and (meth)acrylate having hydroxyalkyl group as a monomer component, and (meth)acrylate having hydroxyalkyl group is included in the monomer component at the rate of 6 wt% or more. The processing method for workpiece in this invention comprises a process of irradiating the adhesive layer of the temperature-sensitive tacky adhesive tape with an ultraviolet light to peel the workpiece from the temperature-sensitive tacky adhesive tape at a temperature less than the above melting point.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a temperature-sensitive adhesive and a method for processing a workpiece.

Background Art

[0002] As an adhesive whose adhesive force changes in response to temperature changes, a temperature-sensitive adhesive is known. The temperature-sensitive adhesive is processed into a tape or the like and is used when temporarily fixing a ceramic green sheet laminate or the like in the manufacturing process of a multilayer ceramic capacitor or the like (see, for example, Patent Document 1).

[0003] For the temporary fixing adhesive, there are required the fixability when processing a workpiece such as a ceramic green sheet laminate and the easy peelability when peeling the processed product obtained by processing the workpiece.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide a temperature-sensitive adhesive excellent in fixability and easy peelability and a method for processing a workpiece.

Means for Solving the Problems

[0006] As a result of intensive studies to solve the above problems, the present inventors have found a solution means having the following configuration and have completed the present invention. (1) A reaction product of a compound having an ultraviolet-curable functional group and a side-chain crystalline polymer, comprising an ultraviolet-curable side-chain crystalline polymer that exhibits fluidity at a temperature above its melting point, wherein the side-chain crystalline polymer contains (meth)acrylate having a linear alkyl group having 16 or more carbon atoms, (meth)acrylate having an alkyl group having 2 to 6 carbon atoms, and (meth)acrylate having a hydroxyalkyl group as monomer components, and the (meth)acrylate having a hydroxyalkyl group is contained in the monomer components in a proportion of 6% by weight or more. (2) The temperature-sensitive adhesive according to (1), which temporarily fixes a workpiece at a temperature below its melting point and peels off the workpiece at a temperature below its melting point by irradiation with ultraviolet light. (3) The temperature-sensitive adhesive according to (1) or (2) above, further containing an azo compound. (4) The temperature-sensitive adhesive according to (3), wherein the content of the azo compound is 5 to 15 parts by weight per 100 parts by weight of the ultraviolet-curable side-chain crystalline polymer. (5) A temperature-sensitive adhesive according to any of (1) to (4) above, for temporary fixing of a ceramic green sheet laminate. (6) A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive described in any of (1) to (5) above. (7) A temperature-sensitive adhesive tape comprising a film-like substrate and an adhesive layer laminated on at least one side of the substrate and containing a temperature-sensitive adhesive according to any of (1) to (5) above. (8) A method for processing a workpiece, comprising the steps of: applying the temperature-sensitive adhesive tape described in (7) above to a workpiece at a temperature above its melting point; temporarily fixing the workpiece to the workpiece by lowering the temperature-sensitive adhesive tape to a temperature below its melting point; processing the workpiece to obtain a workpiece; and irradiating the adhesive layer of the temperature-sensitive adhesive tape with ultraviolet light and peeling the workpiece from the temperature-sensitive adhesive tape at a temperature below its melting point. [Effects of the Invention]

[0007] According to the present invention, there is an effect of excellent fixation and ease of peeling. [Brief explanation of the drawing]

[0008] [Figure 1] (a) to (c) are schematic diagrams illustrating a method for processing a workpiece according to one embodiment of the present invention. [Modes for carrying out the invention]

[0009] <Temperature-sensitive adhesive> The thermosensitive adhesive of this embodiment contains an ultraviolet (UV) curable side-chain crystalline polymer. The UV-curable side-chain crystalline polymer is a reaction product of a compound having UV-curable functional groups and a side-chain crystalline polymer, and exhibits fluidity at temperatures above its melting point. In addition to being UV-curable, this UV-curable side-chain crystalline polymer has thermosensitivity, reversibly changing between a crystalline state and a fluid state in response to temperature changes.

[0010] To explain in more detail, UV-curable side-chain crystalline polymers have a melting point. The melting point is the temperature at which a specific part of the polymer, which was initially aligned in an ordered arrangement, becomes disordered due to a certain equilibrium process. This value is obtained by measuring with a differential thermal scanning calorimeter (DSC) under measurement conditions of 10°C / min.

[0011] The UV-curable side-chain crystalline polymer crystallizes at temperatures below its melting point and undergoes a phase transition above its melting point, exhibiting fluidity. Therefore, when the temperature of the thermosensitive adhesive is heated above its melting point, the UV-curable side-chain crystalline polymer becomes fluid, allowing the thermosensitive adhesive to be applied to the workpiece. Furthermore, when the UV-curable side-chain crystalline polymer exhibits fluidity, the thermosensitive adhesive conforms to the fine irregularities on the workpiece surface. When this thermosensitive adhesive is cooled to a temperature below its melting point, the UV-curable side-chain crystalline polymer crystallizes, resulting in a so-called anchoring effect, which allows the workpiece to be temporarily fixed in place.

[0012] Here, when temporarily fixing the workpiece, high fixing strength is required (fixing ability). Furthermore, when peeling the workpiece obtained from the temperature-sensitive adhesive, it is also required that it be easily peelable (ease of peeling). Regarding peeling, it is conceivable to address this by reducing the fixing strength by making the UV-curable side-chain crystalline polymer into a fluid state, but this approach requires the effort of heating it to a temperature above its melting point.

[0013] In this embodiment, the side-chain crystalline polymer contains (meth)acrylate having a linear alkyl group with 16 or more carbon atoms, (meth)acrylate having an alkyl group with 2 to 6 carbon atoms, and (meth)acrylate having a hydroxyalkyl group as monomer components. The side-chain crystalline polymer contains (meth)acrylate having a hydroxyalkyl group in a proportion of 6% by weight or more in the monomer components.

[0014] With this configuration, it is possible to temporarily fix the workpiece with high fixing force at temperatures below the melting point. Furthermore, (meth)acrylate having a hydroxyalkyl group reacts with compounds having UV-curable functional groups. When the side-chain crystalline polymer contains 6% by weight or more of (meth)acrylate having a hydroxyalkyl group in its monomer components, many compounds having UV-curable functional groups react, and as a result, the UV-curable side-chain crystalline polymer has many UV-curable functional groups. This leads to increased curing shrinkage during UV irradiation, a decrease in adhesion to the workpiece, and a greater likelihood of the anchoring effect being released. Therefore, the fixing force can be sufficiently reduced by UV irradiation. Consequently, there is no need to heat to a temperature above the melting point when peeling, and the workpiece can be easily peeled off at a temperature below the melting point by UV irradiation.

[0015] Thus, according to the thermosensitive adhesive of the present embodiment, the workpiece can be temporarily fixed with a high fixing force at a temperature below the melting point. Moreover, when peeling the workpiece, there is no need to heat it to a temperature above the melting point. Therefore, it has the effect of being excellent in fixability and easy peelability. That is, the thermosensitive adhesive of the present embodiment temporarily fixes the workpiece at a temperature below the melting point and peels the workpiece at a temperature below the melting point by irradiating UV light.

[0016] The thermosensitive adhesive contains a UV-curable and thermosensitive side-chain crystalline polymer at a ratio at which UV curability and thermosensitivity can be obtained. That is, the thermosensitive adhesive contains a UV-curable side-chain crystalline polymer as a main component. The main component means the component most contained in the thermosensitive adhesive by weight ratio.

[0017] The melting point of the UV-curable side-chain crystalline polymer is, for example, 23 to 50 °C, preferably 40 to 50 °C. When the melting point is 40 to 50 °C, the UV-curable side-chain crystalline polymer can be crystallized at room temperature. Therefore, the workpiece can be temporarily fixed with a high fixing force at room temperature and processed. Also, the obtained workpiece can be easily peeled off at room temperature. That is, both the processing of the workpiece and the peeling of the workpiece can be performed at room temperature. Note that room temperature may mean 23 °C ± 5 °C.

[0018] The melting point can be adjusted by changing the composition of the UV-curable side-chain crystalline polymer or the like. Also, the melting point tends not to change substantially before and after UV irradiation. That is, the melting point after UV curing tends to be substantially the same value as the melting point before UV curing. Furthermore, the UV-curable side-chain crystalline polymer crystallizes at a temperature below the melting point even after UV curing and exhibits fluidity at a temperature above the melting point. That is, the UV-curable side-chain crystalline polymer can reversibly change between a crystalline state and a fluid state in response to temperature changes in any state before and after UV irradiation.

[0019] (Meth)acrylate having a linear alkyl group with 16 or more carbon atoms, the linear alkyl group with 16 or more carbon atoms functions as a side-chain crystalline site in the UV-curable side-chain crystalline polymer. That is, the UV-curable side-chain crystalline polymer is a comb-shaped polymer having a linear alkyl group with 16 or more carbon atoms in the side chain, and this side chain crystallizes by being aligned in an orderly arrangement by intermolecular forces or the like.

[0020] Examples of the (meth)acrylate having a linear alkyl group with 16 or more carbon atoms include (meth)acrylates having a linear alkyl group with 16 to 22 carbon atoms such as cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc. The exemplified (meth)acrylate may be used alone or in combination of two or more. (Meth)acrylate means acrylate or methacrylate.

[0021] Examples of the (meth)acrylate having an alkyl group with 2 to 6 carbon atoms include ethyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, etc. The exemplified (meth)acrylate may be used alone or in combination of two or more.

[0022] Examples of the (meth)acrylate having a hydroxyalkyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyhexyl (meth)acrylate, etc. The exemplified (meth)acrylate may be used alone or in combination of two or more.

[0023] As described above, the side-chain crystalline polymer contains 6% by weight or more of (meth)acrylate having a hydroxyalkyl group in the monomer component. The proportion of (meth)acrylate having a hydroxyalkyl group is preferably 8% by weight or more, more preferably 10% by weight or more. The upper limit of the proportion of (meth)acrylate having a hydroxyalkyl group may be 30% by weight or less.

[0024] Furthermore, the side-chain crystalline polymer may contain (meth)acrylates having linear alkyl groups with 16 or more carbon atoms and (meth)acrylates having alkyl groups with 2 to 6 carbon atoms in equal proportions in the monomer components.

[0025] In a side-chain crystalline polymer, (meth)acrylates having linear alkyl groups with 16 or more carbon atoms may be present in a larger weight ratio than (meth)acrylates having alkyl groups with 2 to 6 carbon atoms. In this case, excellent fixation properties are obtained.

[0026] The composition of the side-chain crystalline polymer may include, for example, 10-90% by weight of (meth)acrylate having a linear alkyl group with 16 or more carbon atoms, 4-60% by weight of (meth)acrylate having an alkyl group with 2-6 carbon atoms, and 6-30% by weight of (meth)acrylate having a hydroxyalkyl group.

[0027] Examples of monomer polymerization methods include solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. When using solution polymerization, the monomers mentioned above are mixed in a solvent, polymerization initiators are added as needed, and the mixture is stirred at approximately 40-90°C for 2-10 hours.

[0028] The weight-average molecular weight of the side-chain crystalline polymer is, for example, 100,000 or more, preferably 400,000 to 800,000. The weight-average molecular weight is the value obtained by measuring the side-chain crystalline polymer by gel permeation chromatography (GPC) and converting the obtained measurement to polystyrene equivalent.

[0029] In compounds having UV-curable functional groups, a UV-curable functional group refers to a functional group that hardens upon UV irradiation. Examples of UV-curable functional groups include (meth)acryloyl groups, (meth)acryloyloxy groups, vinyl groups, and glycidyl groups.

[0030] Examples of compounds having UV-curable functional groups include isocyanate compounds that react with the hydroxyalkyl group-containing (meth)acrylates mentioned above. Examples include 2-methacryloyloxyethyl isocyanate represented by formula (I) below, 2-acryloyloxyethyl isocyanate represented by formula (II) below, and 1,1-bis(acryloyloxymethyl)ethyl isocyanate represented by formula (III) below.

[0031] [ka]

[0032] Other isocyanate compounds having UV-curable functional groups other than those in formulas (I) to (III) include, for example, 2-(meth)acryloyloxypropyl isocyanate, 2-(meth)acryloyloxybutyl isocyanate, (meth)acryloyl isocyanate, and 1-(4-vinylphenyl)-1-methylethyl isocyanate. The exemplified isocyanate compounds may be used individually or in combination of two or more.

[0033] The reaction between a compound having UV-curable functional groups and a side-chain crystalline polymer can be carried out, for example, by mixing the two in a predetermined ratio, adding antioxidants and catalysts as needed, and stirring under an inert gas atmosphere such as nitrogen gas at approximately 40-80°C for 1-9 hours.

[0034] The mixing ratio of the two is, for example, 0.1 to 5 molar equivalents, preferably 0.5 to 2 molar equivalents, of the compound having a UV-curable functional group relative to the hydroxyalkyl group in the side-chain crystalline polymer. The content of the side-chain crystalline polymer should be greater than the content of the compound having a UV-curable functional group.

[0035] A photopolymerization initiator is used to cure the UV-curable functional group. The photopolymerization initiator can be appropriately selected according to the composition of the UV-curable functional group and is not particularly limited. Commercially available photopolymerization initiators can also be used. For example, "Omnirad500" from IGM Resins is one example of a commercially available photopolymerization initiator. The amount of photopolymerization initiator to be added is, for example, 0.3 to 3 parts by weight per 100 parts by weight of the UV-curable side-chain crystalline polymer.

[0036] The weight-average molecular weight of the UV-curable side-chain crystalline polymer is, for example, 100,000 or more, preferably 600,000 to 800,000. The weight-average molecular weight is the value obtained by measuring the UV-curable side-chain crystalline polymer by GPC and converting the obtained measurement to polystyrene equivalent.

[0037] The temperature-sensitive adhesive may further contain an azo compound. In this case, gas is generated when irradiated with UV light, resulting in a lifting effect on the workpiece, thus providing superior ease of peeling.

[0038] Examples of azo compounds include azoamides and azoesters. An example of azoamide is 2,2'-Azobis(N-butyl-2-methylpropionamide). The azo compound content is, for example, 5 to 15 parts by weight per 100 parts by weight of UV-curable side-chain crystalline polymer.

[0039] The temperature-sensitive adhesive may further contain a crosslinking agent. Examples of crosslinking agents include metal chelate compounds, aziridine compounds, isocyanate compounds, and epoxy compounds. The crosslinking agent content is, for example, 0.1 to 5 parts by weight per 100 parts by weight of UV-curable side-chain crystalline polymer. The crosslinking conditions are a heating temperature of approximately 90 to 120°C and a heating time of approximately 1 to 20 minutes.

[0040] The temperature-sensitive adhesive may have a 180° peel strength against polyethylene terephthalate of 1.0 N / 25 mm or more, preferably 1.0 to 15 N / 25 mm, at 23°C before UV irradiation, or 0.1 N / 25 mm or less, preferably 0.01 to 0.1 N / 25 mm, at 23°C after UV irradiation. In this case, the temperature-sensitive adhesive has excellent fixation and easy peelability when applied to a workpiece containing organic materials. The 180° peel strength is a value measured in accordance with JIS Z0237.

[0041] The temperature-sensitive adhesive may have a 180° peel strength against stainless steel of 3.0 N / 25 mm or more, preferably 3.0 to 40 N / 25 mm, at 23°C before UV irradiation, or 0.2 N / 25 mm or less, preferably 0.01 to 0.2 N / 25 mm, at 23°C after UV irradiation. In this case, the temperature-sensitive adhesive has excellent fixation and easy peelability when applied to a workpiece containing inorganic materials.

[0042] Temperature-sensitive adhesives can be used, for example, as temporary fixing materials for the manufacture of ceramic components. Examples of ceramic components include multilayer ceramic capacitors, ceramic inductors, and ceramic varistors. Temperature-sensitive adhesives may also be used for temporary fixing of ceramic green sheet laminates.

[0043] The form in which the temperature-sensitive adhesive is used is not particularly limited; for example, it may be used as is, or it may be used in the form of an adhesive sheet, adhesive tape, or the like, as described below.

[0044] <Temperature-sensitive adhesive sheet> The temperature-sensitive adhesive sheet of this embodiment contains the temperature-sensitive adhesive described above and is in the form of a substrate-less sheet. The thickness of the temperature-sensitive adhesive sheet is, for example, 10 to 400 μm.

[0045] A release film may be laminated onto the surface of the temperature-sensitive adhesive sheet. Examples of release films include those made of polyethylene terephthalate or the like, coated with a release agent such as silicone. The thickness of the release film is, for example, 5 to 500 μm, preferably 25 to 250 μm. The release film is peeled off when the temperature-sensitive adhesive sheet is used.

[0046] <Temperature-sensitive adhesive tape> The temperature-sensitive adhesive tape of this embodiment comprises a film-like substrate and an adhesive layer laminated on at least one side of the substrate. The term "film-like" is not limited to film-like structures, but includes film-like or sheet-like structures as long as they do not impair the effects of this embodiment.

[0047] Examples of constituent materials for the base material include synthetic resins such as polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride.

[0048] The substrate structure may be either a single-layer or multi-layer structure. The thickness of the substrate is, for example, 5 to 500 μm, preferably 25 to 250 μm. The substrate may be surface-treated to improve adhesion to the adhesive layer. Examples of surface treatments include corona discharge treatment (corona treatment), plasma treatment, blasting, chemical etching, and primer treatment.

[0049] The adhesive layer laminated on at least one side of the substrate contains the temperature-sensitive adhesive described above. To laminate the adhesive layer on at least one side of the substrate, for example, a coating solution can be prepared by adding a solvent to the temperature-sensitive adhesive, and the resulting coating solution can be applied to one or both sides of the substrate using an applicator, coater, etc., and then dried. Examples of applicators include baker-type applicators. Examples of coaters include knife coaters, roll coaters, calender coaters, comma coaters, gravure coaters, rod coaters, etc.

[0050] The thickness of the adhesive layer is, for example, 5 to 300 μm, preferably 10 to 300 μm.

[0051] When adhesive layers are laminated on both sides of a substrate, the adhesive layers on one side and the adhesive layer on the other side may have the same composition and thickness, or they may be different. Furthermore, as long as the adhesive layer on one side contains the temperature-sensitive adhesive described above, the adhesive layer on the other side is not particularly limited. The adhesive layer on the other side may be composed of, for example, natural rubber-based adhesives, synthetic rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, etc.

[0052] A release film may be laminated on the surface of the adhesive layer. Examples of release films include those exemplified above for the temperature-sensitive adhesive sheet. The release film is peeled off when the temperature-sensitive adhesive tape is used.

[0053] <Processing method of workpiece> Next, a method for processing a workpiece according to one embodiment of the present invention will be described in detail with reference to Figure 1, taking the case where the workpiece is a ceramic green sheet laminate as an example.

[0054] The workpiece processing method of this embodiment uses the temperature-sensitive adhesive tape described above and includes the following steps (i) to (iv). (i) A step of heating a temperature-sensitive adhesive tape to a temperature above its melting point and attaching it to the workpiece. (ii) A step of temporarily fixing the workpiece by heating the temperature-sensitive adhesive tape to a temperature below its melting point. (iii) The process of processing a workpiece to obtain a workpiece. (iv) A step of irradiating the adhesive layer of a temperature-sensitive adhesive tape with ultraviolet light and peeling the workpiece from the temperature-sensitive adhesive tape at a temperature below its melting point.

[0055] To explain in more detail, as shown in Figure 1(a), the temperature-sensitive adhesive tape 1 of this embodiment comprises a film-like base material 2 and an adhesive layer 3 laminated on one side of the base material 2 and containing the temperature-sensitive adhesive described above.

[0056] In step (i), the temperature-sensitive adhesive tape 1 is heated to a temperature above its melting point and attached to the workpiece, the ceramic green sheet laminate 100. To heat the temperature-sensitive adhesive tape 1 to a temperature above its melting point, a heating means such as a heater can be used.

[0057] The ceramic green sheet laminate 100 can be obtained, for example, by forming a ceramic green sheet by thinly spreading a slurry of ceramic powder with a doctor blade, printing multiple electrodes on the surface of this ceramic green sheet, and then laminating multiple ceramic green sheets together.

[0058] In step (ii), the temperature-sensitive adhesive tape 1 is cooled to a temperature below its melting point to temporarily fix the ceramic green sheet laminate 100. According to this embodiment, since the adhesive layer 3 contains the temperature-sensitive adhesive described above, the ceramic green sheet laminate 100 can be temporarily fixed with high fixing force. To cool the temperature-sensitive adhesive tape 1 to a temperature below its melting point, for example, a cooling means such as a fan can be used.

[0059] In step (iii), the ceramic green sheet laminate 100 is processed to obtain a workpiece. Examples of processing methods include cutting and polishing. Step (iii) in this embodiment is a so-called dicing process, as shown in Figure 1(b). Specifically, in step (iii) of this embodiment, the ceramic green sheet laminate 100 is cut with a rotary blade 200 to obtain a plurality of raw chips 110 as a workpiece.

[0060] In step (iv), as shown in Figure 1(c), UV light is irradiated onto the adhesive layer 3 of the temperature-sensitive adhesive tape 1, and multiple raw chips 110 are peeled off from the temperature-sensitive adhesive tape 1 at a temperature below the melting point. The amount of UV irradiation is, for example, 0.5 to 3 J / cm². 2 That is the case.

[0061] In this embodiment, since the adhesive layer 3 contains the temperature-sensitive adhesive described above, irradiating the adhesive layer 3 with UV light can sufficiently reduce the fixing force at a temperature below its melting point. Therefore, multiple raw chips 110 can be easily peeled off the temperature-sensitive adhesive tape 1 at a temperature below its melting point, and multiple raw chips 110 can be obtained with a good yield.

[0062] If the melting point is 40-50°C, the ceramic green sheet laminate 100 can be temporarily fixed with high fixing force at room temperature in step (ii). In step (iii), the ceramic green sheet laminate 100 can be diced at room temperature. In step (iv), multiple raw chips 110 can be easily peeled off the temperature-sensitive adhesive tape 1 at room temperature.

[0063] When the obtained raw chip 110 is fired, a ceramic chip can be obtained. Furthermore, when external electrodes are formed on the end face of the obtained ceramic chip, a multilayer ceramic capacitor can be obtained.

[0064] Although embodiments of the present invention have been illustrated above, it goes without saying that the present invention is not limited to the embodiments described above, and can be any embodiment without departing from the spirit of the invention.

[0065] For example, in the workpiece processing method of the above-described embodiment, the workpiece is a ceramic green sheet laminate 100. However, the workpiece processing method of this embodiment can also be applied to workpieces when manufacturing other ceramic components, such as ceramic inductors and ceramic varistors, in addition to the ceramic green sheet laminate 100.

[0066] Furthermore, in step (i) of the processing method for the workpiece, the base material 2 of the temperature-sensitive adhesive tape 1 may be fixed to the base. Methods for fixing the base material 2 to the base include, for example, a method of fixing by interposing a predetermined adhesive or bonding agent between the base material 2 and the base, or a method of employing a base equipped with fixing means such as an adsorption mechanism. In addition, if the temperature-sensitive adhesive tape 1 is a double-sided tape in which adhesive layers 3 are laminated on both sides of the base material 2, it may be fixed to the base via the adhesive layer 3 on one side that fixes the ceramic green sheet laminate 100 and the adhesive layer 3 on the opposite side.

[0067] Furthermore, in step (iii) of the workpiece processing method, instead of cutting with the rotary blade 200, for example, a push cut with a cutting blade may be used.

[0068] The present invention will be described in detail below with reference to synthesis examples and embodiments, but the present invention is not limited to the following synthesis examples and embodiments.

[0069] (Synthesis Examples 1-2) First, behenyl acrylate, n-butyl acrylate, and 2-hydroxyethyl acrylate were mixed in the proportions shown in Table 1 to obtain a monomer mixture.

[0070] Next, "Perbutyl ND" manufactured by NOF Corporation was added as a polymerization initiator at a ratio of 0.3 parts by weight per 100 parts by weight of the monomer mixture. The mixture was then adjusted to a solid content of 32% by weight using a mixed solvent of ethyl acetate:heptane = 7:3 (by weight ratio) to obtain a mixed solution.

[0071] Next, the resulting mixture was stirred at 55°C for 4 hours. Then, "Perbutyl PV" manufactured by NOF Corporation was added as an additional polymerization initiator at a ratio of 0.5 parts by weight per 100 parts by weight of the monomer mixture. The mixture was then stirred further at 80°C for 2 hours to copolymerize each monomer and obtain a solution of side-chain crystalline polymer.

[0072] 100 parts by weight of the obtained side-chain crystalline polymer solution (based on solid content), 10.5 parts by weight of 2-methacryloyloxyethyl isocyanate represented by formula (I) above ("Kalenz MOI," a UV-curable functional compound manufactured by Showa Denko K.K.), (0.8 molar equivalents relative to the hydroxyalkyl group in the side-chain crystalline polymer), and 0.1 parts by weight of zirconium tetraacetylacetonate ("Orgatics ZC-150," manufactured by Matsumoto Fine Chemical Co., Ltd.) as a catalyst were mixed and reacted under a nitrogen gas atmosphere with stirring at 50°C for 8 hours to obtain a UV-curable side-chain crystalline polymer solution.

[0073] (Comparative Synthesis Example 1) First, a monomer mixture was obtained by mixing behenyl acrylate in a ratio of 45% by weight, methyl acrylate in a ratio of 50% by weight, and 2-hydroxyethyl acrylate in a ratio of 5% by weight.

[0074] Next, each monomer was copolymerized in the same manner as in Synthesis Examples 1 and 2, except that this monomer mixture was used, to obtain a solution of a side-chain crystalline polymer. Then, using this solution of the side-chain crystalline polymer, the reaction was carried out in the same manner as in Synthesis Examples 1 and 2, except that the proportion of 2-methacryloyloxyethyl isocyanate was 5.3 parts by weight (0.8 molar equivalents relative to the hydroxyalkyl group in the side-chain crystalline polymer), to obtain a solution of a UV-curable side-chain crystalline polymer.

[0075] (Comparative Synthesis Example 2) First, a monomer mixture was obtained by mixing behenyl acrylate in a ratio of 45% by weight, n-butyl acrylate in a ratio of 50% by weight, and 2-hydroxyethyl acrylate in a ratio of 5% by weight.

[0076] Next, each monomer was copolymerized in the same manner as in Synthesis Examples 1 and 2, except that this monomer mixture was used, to obtain a solution of a side-chain crystalline polymer. Then, using this solution of the side-chain crystalline polymer, the reaction was carried out in the same manner as in Synthesis Examples 1 and 2, except that the proportion of 2-methacryloyloxyethyl isocyanate was 5.3 parts by weight (0.8 molar equivalents relative to the hydroxyalkyl group in the side-chain crystalline polymer), to obtain a solution of a UV-curable side-chain crystalline polymer.

[0077] Table 1 shows the weight-average molecular weight and melting point of each UV-curable side-chain crystalline polymer obtained in Synthesis Examples 1-2 and Comparative Synthesis Examples 1-2. The weight-average molecular weight is the value obtained by GPC and converted to polystyrene equivalent. The melting point was measured using DSC under a measurement condition of 10°C / min.

[0078] [Table 1]

[0079] [Examples 1-7 and Comparative Examples 1-2] <Preparation of temperature-sensitive adhesive tape> First, 100 parts by weight (based on solid content) of the solutions of each UV-curable side-chain crystalline polymer obtained in Synthesis Examples 1-2 and Comparative Synthesis Examples 1-2 were mixed with 1 part by weight (based on solid content) of the photopolymerization initiator "Omnirad500" manufactured by IGM Resins, and with the crosslinking agent and azo compound in the proportions shown in Table 2 to obtain coating solutions.

[0080] The proportions of crosslinking agents and azo compounds shown in Table 2 are based on solid content, relative to 100 parts by weight of UV-curable side-chain crystalline polymer. The crosslinking agents and azo compounds used are as follows: Crosslinking agent: "Coronate L-45E," an isocyanate compound manufactured by Nippon Polyurethane Industries Co., Ltd. Azo compound: 2,2'-Azobis(N-butyl-2-methylpropionamide)

[0081] Next, the obtained coating solution was applied to one side of the substrate and dried to obtain a temperature-sensitive adhesive tape with a 40 μm thick adhesive layer laminated on one side of the substrate. The substrate used, coating conditions, and drying conditions (crosslinking conditions) are as follows. Substrate: A film-like substrate made of polyethylene terephthalate with a thickness of 100 μm, with one side corona-treated, was used. Coating conditions: The coating solution was applied to the corona-treated surface of the substrate using an applicator. Drying conditions: Dried in a 100°C dryer for 5 minutes.

[0082] <Rating> The 180° peel strength was evaluated for each temperature-sensitive adhesive tape obtained in Examples 1-7 and Comparative Examples 1-2. The evaluation method is described below, and the results are shown in Table 2.

[0083] (180° peel strength) The 180° peel strength of the obtained temperature-sensitive adhesive tape against polyethylene terephthalate (PET) and stainless steel (SUS) at an ambient temperature of 23°C before and after UV irradiation was measured. The 180° peel strength was measured in accordance with JIS Z0237. Specifically, the temperature-sensitive adhesive tape was applied to PET and SUS under the following conditions, and then peeled off at a speed of 300 mm / min using a load cell.

[0084] [23℃ before UV irradiation] Temperature-sensitive adhesive tape was applied to PET and SUS at an ambient temperature of 60°C, left to stand for 20 minutes, then the ambient temperature was lowered to 23°C, left to stand for another 20 minutes, and then peeled off at a 180° angle.

[0085] [23℃ after UV irradiation] Temperature-sensitive adhesive tape was applied to PET and SUS at an ambient temperature of 60°C, and left to stand for 20 minutes. Then, the ambient temperature was lowered to 23°C, left to stand for another 20 minutes, and the adhesive layer was irradiated with UV light.

[0086] The UV irradiation conditions are as follows: Equipment: Belt-type UV irradiation device Light source: High-pressure mercury lamp UV irradiation amount: 1J / cm 2

[0087] After UV irradiation, the sample was left to stand for 20 minutes at an ambient temperature of 23°C before being peeled off at 180°.

[0088] The PET used was a 0.25 mm thick film with an untreated surface. The SUS used was a sheet of SUS304. The temperature-sensitive adhesive tape was applied to the PET and SUS by rolling a 2 kg roller back and forth five times over the temperature-sensitive adhesive tape.

[0089] [Table 2]

[0090] As is clear from Table 2, Examples 1 to 7 showed high 180° peel strength values ​​at 23°C before UV irradiation and low 180° peel strength values ​​at 23°C after UV irradiation for both PET and SUS. Therefore, Examples 1 to 7 can be said to allow temporary fixing of the workpiece at a temperature below its melting point and peeling of the workpiece at a temperature below its melting point by UV irradiation.

[0091] Comparative Example 1 easily peeled off from PET and SUS at an ambient temperature of 23°C, making it impossible to measure the 180° peel strength at 23°C before UV irradiation, thus demonstrating poor fixation. For reference, the 180° peel strength value at 80°C before UV irradiation is shown in the "23°C before UV irradiation" column in Table 2.

[0092] Comparative Example 2 showed high 180° peel strength values ​​at 23°C after UV irradiation for both PET and SUS, and poor peelability at temperatures below the melting point after UV irradiation. [Explanation of Symbols]

[0093] 1. Temperature-sensitive adhesive tape 2...Base material 3. Adhesive layer 100... Ceramic green sheet laminate 110... Raw chips 200... Rotary blades

Claims

1. A reaction product of a compound having an ultraviolet-curable functional group and a side-chain crystalline polymer, comprising an ultraviolet-curable side-chain crystalline polymer that exhibits fluidity at temperatures above its melting point, The side-chain crystalline polymer contains a (meth)acrylate having a linear alkyl group with 16 or more carbon atoms, a (meth)acrylate having an alkyl group with 2 to 6 carbon atoms, and a (meth)acrylate having a hydroxyalkyl group as monomer components, and contains the (meth)acrylate having a hydroxyalkyl group in a proportion of 6% by weight or more in the monomer components. A temperature-sensitive adhesive that temporarily fixes a workpiece at a temperature below its melting point and allows the workpiece to be peeled off at a temperature below its melting point by irradiation with ultraviolet light.

2. The temperature-sensitive adhesive according to claim 1, further containing an azo compound.

3. The temperature-sensitive adhesive according to claim 2, wherein the content of the azo compound is 5 to 15 parts by weight per 100 parts by weight of the ultraviolet-curable side-chain crystalline polymer.

4. A temperature-sensitive adhesive according to any one of claims 1 to 3, for temporary fixing of a ceramic green sheet laminate.

5. A temperature-sensitive adhesive sheet comprising the temperature-sensitive adhesive according to any one of claims 1 to 4.

6. A film-like substrate and A temperature-sensitive adhesive tape comprising: an adhesive layer laminated on at least one side of the substrate and containing a temperature-sensitive adhesive according to any one of claims 1 to 4.

7. A step of applying the temperature-sensitive adhesive tape described in claim 6 to a workpiece at a temperature above its melting point, A step of temporarily fixing the workpiece by heating the temperature-sensitive adhesive tape to a temperature below its melting point, A step of processing the aforementioned workpiece to obtain a workpiece, A method for processing a workpiece, comprising the steps of irradiating the adhesive layer of the temperature-sensitive adhesive tape with ultraviolet light and peeling the workpiece from the temperature-sensitive adhesive tape at a temperature below its melting point.

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