TWI841538B - Method for manufacturing laminate containing hardening bonding material - Google Patents

Abstract

The present invention relates to a method for manufacturing a laminate containing a hardening bonding material, wherein the laminate comprises a bonded body (C1) and a bonding material (X), and the manufacturing method sequentially comprises: step [1] of activating a reactive site of the bonding material (X); step [2] of attaching the bonding material (X) to the bonded body (C1); and step [3] of hardening the bonding material (X). According to the present invention, a novel laminate can be manufactured that is easy to fix components and can be constructed in a short time and at a low temperature, and can therefore be used in materials for firmly bonding various components used specifically for image display devices.

Description

Method for manufacturing laminate containing hardening bonding material

The present invention relates to a method for manufacturing a laminate using a laminated bonding material that can be used as a component used in an image display device.

In recent years, liquid crystal display devices have been widely used as display devices for televisions, smart phones, personal assistant devices (PADs), tablet computers, car navigation systems, etc.

As the liquid crystal display device, it is generally known that it has a structure in which components such as a liquid crystal display panel, a planar lighting device (backlight device), a circuit board (substrate) or a chassis on which other electronic components are mounted, and a heat sink are stacked. The planar lighting device (backlight device) is overlapped and arranged on the back of the liquid crystal display panel to illuminate the liquid crystal display panel, and the heat sink diffuses the heat generated by the components.

In order to stack the components of the liquid crystal display device, the purpose is usually to firmly fix the components to each other and prevent the components from falling off over time. Most of them use a method of bonding the two components to each other by interposing a bonding layer composed of an epoxy adhesive, a urethane adhesive, etc. between the components (for example, refer to Patent Document 1).

In addition, in the method of bonding the components to each other, for example, when the surface of the component to be layered has warps or bumps, in order to remove the uneven thickness of the coated surface after applying the adhesive and making the adhesive follow the warps or bumps, the method includes the following steps: smoothing the surface coated with the adhesive by scraping the applied adhesive, and then layering another component (for example, refer to Patent Document 2).

In current manufacturing, in order to ensure the construction time required for the above-mentioned lamination step, an adhesive with a long curing time must be used. As a result, a long curing step is required until the adhesive after the above-mentioned lamination step shows sufficient bonding strength.

As a method to promote the curing of the adhesive after the lamination step, the heat curing of the adhesive has also been studied, but there is a risk that the components of the liquid crystal display device will be damaged by the heat during curing. In addition, there are problems in the bonding method using adhesives, such as deformation of the components due to the strain between the components generated during cooling due to the difference in thermal expansion of each component, or cracks between the bonding material and the components causing separation.

In addition, if an adhesive with excellent curability at room temperature is used in order to shorten the curing time, the construction time required for the lamination step cannot be guaranteed. In addition, in order to harden before lamination, sufficient bonding strength may not be exhibited during lamination.

In addition, as a method to complete hardening at low temperature in a short time, a bonding method using light irradiation has also been studied, but it cannot be used in components that cannot transmit light, and the application components are limited, making practical application difficult.

Based on the above background, there is now a strong demand for a novel joining method that can complete the construction in a short time and at a low temperature, and can better join even for opaque materials.

[Prior art literature]

[Patent Literature]

[Patent document 1] Japanese Patent No. 5546136

[Patent Document 2] Japanese Patent Publication No. 2003-136677

The problem that the present invention aims to solve is to provide a novel method for manufacturing a laminate, which can be constructed in a short time and at a low temperature, and can be better bonded even to opaque materials.

The inventors of the present invention focused on the manufacturing method of the laminate and conducted diligent research. As a result, they found that the problem can be solved by a manufacturing method including the following steps [1] to [3], thereby completing the present invention.

That is, the present invention is a method for manufacturing a laminate containing a hardenable bonding material, wherein the laminate comprises a bonded body (C1) and a bonding material (X), and the manufacturing method sequentially comprises: step [1], activating the reaction site of the bonding material (X); step [2], attaching the bonding material (X) to the bonded body (C1); and step [3], hardening the bonding material (X).

In the present invention, the reaction site of the bonding material (X) is activated, so that the hardening reaction of the bonding material (X) can be carried out in a short time and at a low temperature.

In the present invention, after activating the reaction site of the bonding material (X), it can be attached to the adherend (C1), so it can be applied to various components such as components that cannot transmit light.

The manufacturing method of the laminate containing a hardenable bonding material of the present invention is the following manufacturing method, wherein the manufacturing method comprises the following steps: step [1], activating the reaction site of the bonding material (X); step [2], attaching the bonding material (X) to the bonded body (C1); and step [3], hardening the bonding material (X).

The manufacturing method of the present invention attaches the bonding material (X) to the adherend (C1) after activating the reactive part of the bonding material (X), so that the bonding material (X) can be hardened in a state where the reactivity is improved. In this way, hardening can be performed at a lower temperature than in a state where activation is not performed. In addition, hardening can be performed in a shorter time than in a state where activation is not performed.

The manufacturing method of the present invention includes a step of activating the reaction site of the bonding material (X) in step [1], wherein the bonding material (X) has a reaction site in the material. The so-called reaction site refers to a site that is activated by applying an external stimulus and becomes capable of reacting with other sites.

Methods for activating the reactive part of the bonding material (X) include heat, light, moisture, etc., but are not limited thereto. However, it is preferred to use heat or light, and it is more preferred to use light. The bonding material (X) activated by light has good storage stability, and the reactive part can be activated at low temperature. In addition, the external stimulus can be used alone or in combination.

As methods for activating the reaction sites using the light, photoradical polymerization, photocation polymerization, and photoion polymerization can be listed. Photocation polymerization or photoion polymerization is preferred because it is not hindered by oxygen during curing and continues to react even after irradiation with light. In addition, even for components that do not transmit light, it can be bonded to the bonded volume layer after irradiating the bonding material with light. Furthermore, photocation polymerization is preferred because it has excellent reactivity during light irradiation and is easy to obtain high bonding after curing. In addition, these polymerization methods can be used alone or in combination.

In addition, the manufacturing method of the present invention is a manufacturing method for manufacturing a laminated body including a bonded body (C1) and a bonded body (C2) separated by a bonding material (X), the manufacturing method sequentially comprising: step [01] of attaching the bonding material (X) to the bonded body (C2); step [1] of activating the reaction site of the bonding material (X); step [2] of attaching to the bonded body (C1); and step [3] of hardening the bonding material (X), wherein a step of performing step tracking (maintenance step) [02] is included between the step [01] and the step [1], and between the step [2] and the step [3].

In the step of performing step-difference tracking in step [02], the bonding material (X) is attached to the adherend (C1) and/or adherend (C2) where there are bends and/or bumps, and the bends and/or bumps are filled.

Regarding the step [02], hardening begins after the step [1] of activating the reaction site of the bonding material (X). Therefore, if any of the adherends to be bonded by the present manufacturing method has warps and/or irregularities, in order to sufficiently ensure the time (curing time) for the bonding material to follow the steps of the warps and/or irregularities, the step [02] is preferably performed after the step [01] and before the step [1].

The step [01] may also include a heating step within a range where the laminated components are not damaged or the bonding material does not deform or flow excessively. By including the heating step, when the bonding material (X) is attached to the adherend (C2), it can be more firmly bonded and a high bonding strength can be obtained.

In the step [01], the heating temperature is preferably 10°C or higher and 150°C or lower, more preferably 20°C or higher and 120°C or lower, further preferably 30°C or higher and 100°C or lower, and most preferably 40°C or higher and 90°C or lower. By setting the temperature within the above range, damage to the components can be suppressed, while excessive deformation of the bonding material can be suppressed, and a higher bonding strength can be obtained by more firmly bonding.

The step [02] may also include a heating step within the range where the laminated components are not damaged or the bonding material does not deform excessively and flow. By including the heating step, the time required for the bonding material (X) to follow the bonded body (C2) can be shortened at any time, and the manufacturing method of the present invention can be completed in a short time.

In the step [02], the heating temperature is preferably 20°C or higher and 150°C or lower, more preferably 40°C or higher and 120°C or lower, further preferably 55°C or higher and 100°C or lower, and most preferably 70°C or higher and 90°C or lower. By setting the temperature within the above range, the step tracking can be performed while suppressing damage to the laminated components or excessive deformation of the bonding material during the step tracking.

The step [2] is preferably performed within 24 hours after the step [1], more preferably within 12 hours, further preferably within 3 hours, and most preferably within 1 hour. By setting it within the above range, when the bonding material (X) is attached to the adherend (C1), it can be more firmly bonded and a high bonding strength can be obtained.

The step [2] can also be performed while heating and bonding within a range where the component is not damaged by the accumulation, the component is not deformed by the strain between the components, or cracks are not generated between the bonding material and the component. By including the heating step, when the bonding material (X) is bonded to the adherend (C1), it is possible to obtain a higher bonding strength by more firmly bonding.

In the step [2], the heating temperature is preferably 10°C to 150°C, more preferably 20°C to 120°C, further preferably 30°C to 100°C, and most preferably 40°C to 80°C. By setting the temperature within the above range, damage to the components can be suppressed, while excessive deformation of the bonding material can be suppressed, and a higher bonding strength can be obtained by more firmly bonding.

The step [3] includes the step of hardening the bonding material (X). By hardening the bonding material (X), the bonding material (X) and the adherend (C1) can be more firmly bonded to obtain a high bonding strength.

The step [3] may also include a heating step within a range where no damage to the laminated components occurs, no deformation of the components occurs due to strain between the components, or no cracks occur between the bonding material and the components. By including the heating step, the time required for the bonding material (X) to harden after the bonding material (X) and the adherend (C1) are laminated can be shortened, and the manufacturing method of the present invention can be completed in a short time.

In the step [3], the heating temperature is preferably 20°C or higher and 150°C or lower, more preferably 40°C or higher and 120°C or lower, further preferably 55°C or higher and 100°C or lower, and most preferably 70°C or higher and 90°C or lower. By setting the temperature within the above range, damage to the components can be suppressed, and deformation of the components caused by strain between the components or cracks between the bonding material and the components can be prevented.

The bonding material (X) preferably has a storage modulus of 5.0×10 ³ Pa or more during bonding in the step [01], more preferably 5.0×10 ⁴ Pa to 1.0×10 ⁸ Pa, and even more preferably 5.0×10 ⁵ Pa to 1.0×10 ⁷ Pa. By setting the storage modulus within the above range, the bonding material can be easily handled before hardening and deformation and flow of the bonding material can be suppressed.

Furthermore, in the step [02], the storage elastic coefficient of the bonding material (X) when following the step is preferably less than 5.0×10 ³ Pa, more preferably less than 1.0×10 ³ Pa, and even more preferably less than 1.0×10 ² Pa. By setting the bonding material within the above range, a bonding material having further improved followability to the step portion can be obtained.

The storage elastic coefficient of the bonding material (X) at 25°C after the step [3] is preferably 1.0×10 ⁵ Pa or more, more preferably 1.0×10 ⁶ Pa or more, and even more preferably 1×10 ⁸ Pa or more. By setting it within the above range, the bonding strength of the cured product of the bonding material (X) can be further improved.

Furthermore, the storage elastic coefficient of the bonding material (X) is a value measured at a frequency of 1.0 Hz.

As the bonding material (X) used in the manufacturing method of the present invention, a composition containing the polymerizable compound described later can be used. The polymerizable compound is not particularly limited as long as it is polymerized by external stimulation.

As the bonding material (X), it is preferred to use one that is pre-formed into a sheet shape in terms of excellent workability before hardening and easy thickness adjustment.

As the sheet-shaped bonding material, it is preferred to use a bonding material with a thickness in the range of 50μm to 2000μm, more preferably 100μm to 1000μm, and most preferably 200μm to 800μm. By setting it within the above range, the operability before hardening is excellent, and even those with unevenness or curvature on the surface of the adherend can be followed.

As the polymerizable compound, it is preferred to contain a thermopolymerizable compound or a photopolymerizable compound, but the use of a photopolymerizable compound is more preferred because it can improve the storage stability of the bonding material (X) before the manufacturing step [1] and can activate the reaction site at a low temperature.

As the photopolymerizable compound, for example, there can be listed photoradical polymerizable compounds, photocationic polymerizable compounds, photoanion polymerizable compounds, etc. These can be used alone or in combination. The use of photocationic polymerizable compounds or photoanion polymerizable compounds is preferred because they are not hindered by oxygen during curing and continue to react after light irradiation. In addition, after irradiating the bonding material with light, they are layered with the bonded volume, thereby laminating even components that do not transmit light. Furthermore, the use of photocationic polymerizable compounds is more preferred because they have excellent reactivity after light irradiation and are easy to obtain high bonding after curing.

The cationic polymerizable compound is not particularly limited as long as it is a compound having one or more cationic polymerizable functional groups in one molecule. As the photo-cationic polymerizable compound, a compound having one or more cationic polymerizable functional groups such as epoxy group, cyclobutyl group, hydroxyl group, vinyl ether group, cyclothio group, ethyleneimine group, oxazoline group, etc. in one molecule is preferred. Among them, cationic polymerizable compounds having epoxy groups are more preferred in terms of obtaining high curability and bonding strength after curing.

As the epoxy resin, a compound having one or more epoxy groups in one molecule can be used. Specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, tetramethylbiphenyl type epoxy resin, polyhydroxynaphthalene type epoxy resin, isocyanate modified epoxy resin, 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxo-10-phosphophenanthrene-10-oxide modified epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, hexanediol type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, Epoxy resins, phenol aralkyl type epoxy resins, naphthol novolac type epoxy resins, naphthol aralkyl type epoxy resins, naphthol-phenol co-phenol novolac type epoxy resins, naphthol-cresol co-phenol novolac type epoxy resins, aromatic hydrocarbon formaldehyde resin modified phenol resin type epoxy resins, biphenyl modified novolac type epoxy resins, trihydroxymethylpropane type epoxy resins, aliphatic epoxy resins, acrylic resins with epoxy groups, polyurethane resins with epoxy groups, polyester resins with epoxy groups, flexible epoxy resins, etc.

Among them, as the epoxy resin, an aliphatic epoxy resin or a multifunctional aliphatic epoxy resin is used, and since the cationic polymerization property is excellent, a bonding material with excellent curing property can be obtained.

Furthermore, other resin components may be blended or added to these resins to improve flexibility, or to improve adhesion or bending strength. As the modified body, carboxyl-terminated butadiene acrylonitrile (CTBN) can be used to modify epoxy resin; acrylic rubber, acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR) can be modified to improve the elasticity of the epoxy resin. Epoxy resins dispersed in various rubbers such as butyl rubber, SBR), butyl rubber or isoprene rubber; epoxy resins modified by the liquid rubber; epoxy resins added with various resins such as acrylic acid, urethane, urea, polyester, styrene, etc.; chelate-modified epoxy resins; polyol-modified epoxy resins, etc.

Specific examples of photocationically polymerizable compounds having a cationically polymerizable functional group other than an epoxide group include 1,4-bis[(3-ethyl-3-oxocyclobutylmethoxy)methyl]benzene, 1,4-bis[(3-methyl-3-oxocyclobutylmethoxy)methyl]benzene, 3-methyl-3-glycidyloxycyclobutane, 3-ethyl-3-glycidyloxycyclobutane, 3-methyl-3-hydroxymethyloxycyclobutane, 3-ethyl-3-hydroxymethyloxycyclobutane, di{1-ethyl(3-oxocyclobutyl)}methyl ether and other oxycyclobutane compounds.

As the bonding material (X) used in the manufacturing method of the present invention, a bonding material containing other components as needed in addition to the above-mentioned polymerizable compound can be used.

As the bonding material (X) used in the manufacturing method of the present invention, it is preferred to use a polymerization initiator that can react with the polymerizable compound.

As the polymerization initiator, any initiator that is activated by external stimulation may be used. For example, if a cationic polymerizable compound is used as the polymerizable compound, it is preferred to use a functional group that can react with a cationic polymerizable functional group.

In addition, as the polymerization initiator, there are photopolymerization initiators and thermal polymerization initiators, which can be used alone or in combination. Among them, in order to obtain a reaction at a low temperature and a good curing reaction, it is better to use a photopolymerization initiator that reacts with light as an external stimulus. In this way, high bonding strength can be obtained without damaging the stacked components, or deforming the components due to strain between the components, or cracks between the bonding materials and the components.

As the light, appropriate light such as ultraviolet light or visible light can be used, but it is preferred to use light with a wavelength of more than 300nm and less than 420nm.

As the photopolymerization initiator, any one that is activated by light may be used, for example, a photoradical polymerization initiator, a photocationic polymerization initiator, and a photoanionic polymerization initiator. For example, if a photocationic polymerization compound is used as the polymerizable compound, it is preferred to use a photocationic polymerization initiator.

As the photo-cationic polymerization initiator, there is no particular limitation as long as it can induce the ring-opening reaction of the cationic polymerizable functional group by light of the wavelength used. Preferably, a compound can be used that can induce the ring-opening reaction of the cationic polymerizable functional group by light of a wavelength of 300nm to 370nm and is inert in the wavelength region exceeding 370nm. Examples of the compound include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic stigmatinium salts.

Specific examples of the onium salts include: Optomer SP-150, Optomer SP-170, Optomer SP-171 (all manufactured by ADEKA), UVE-1014 (manufactured by General Electronic), OMNICAT 250, OMNICAT 270 (all manufactured by IGM Resin), IRGACURE 290 (manufactured by BASF), Sunaide SI-60L, Sunaide SI-80L, Sunaide SI-100L (all manufactured by San-Shin Chemical Industry), CPI-100P, CPI-101A, CPI-200K (all manufactured by San-Apro), etc.

Furthermore, the photo-catalytic ion polymerization initiator can be used alone or in combination of two or more. Furthermore, multiple photo-catalytic ion polymerization initiators with different effective active wavelengths can be used to perform two-stage curing.

The photocatalytic ion polymerization initiator can also be used together with anthracene-based, thiothionone-based, and other sensitizers as needed.

As for the mixing ratio of the photo-cationic polymerization initiator, it is preferably used in the range of 0.001 to 30 parts by mass, more preferably in the range of 0.01 to 20 parts by mass, and further preferably in the range of 0.1 to 10 parts by mass relative to 100 parts by mass of the photo-cationic polymerization initiator. If the mixing ratio of the photo-cationic polymerization initiator is too small, the hardening required for the manifestation of high bonding strength becomes insufficient. If it is too large, the hardening property is improved, but sometimes the time for attachment after light irradiation becomes too short.

As the bonding material (X), it is preferred to use an adhesive resin with a weight average molecular weight in the range of 2000 to 2000000 in terms of excellent workability before curing and easy thickness adjustment. A more preferred weight average molecular weight range is 5000 to 1000000, and a further preferred weight average molecular weight range is 5000 to 800000. If the weight average molecular weight is too small, the cohesion of the bonding material before curing is insufficient, and the workability is reduced due to the leakage of the bonding material over time. In addition, if the weight average molecular weight is too large, the compatibility with the polymerizable compound may be reduced.

Examples of the adhesive resin include polyester, polyurethane, poly(meth)acrylate, etc. These adhesive resins may be homopolymers or copolymers. In addition, these adhesive resins may be used alone or in combination of two or more.

As the adhesive resin, it is preferred that the adhesive resin has adhesiveness at room temperature, so that the adhesion of the bonding material when layered on the adherend is improved. In order to give the adhesive resin adhesiveness, it is preferred that the glass transition temperature of the adhesive resin is in the range of -40°C to 20°C, and more preferably in the range of -30°C to 10°C. By giving the glass transition temperature in the above range, the adhesive layer can be given adhesiveness and a high elastic modulus, and the bonding strength of the bonding material can be improved. Furthermore, the glass transition temperature of the adhesive resin can be calculated, for example, as the temperature at which the loss tangent (Tanδ) calculated by sandwiching the test piece between parallel disks as the measuring part of the dynamic viscoelastic tester (manufactured by Rheometrics, trade name: ARES 2KSTD) and measuring the storage elastic modulus (G') and loss elastic modulus (G") at a frequency of 1.0 Hz reaches a maximum value.

The adhesive resin can be cross-linked, so a functional group that can react with the cross-linking agent or the functional group contained in the polymerizable compound can also be introduced. Examples of the functional group include hydroxyl, carboxyl, epoxy, and amine groups, and it is preferred to select them appropriately within the range that does not hinder the polymerization of the polymerizable compound.

The adhesive resin is preferably used in a range of 5 to 900 parts by mass relative to 100 parts by mass of the curable resin, more preferably in a range of 10 to 700 parts by mass, and further preferably in a range of 20 to 400 parts by mass. If the mixing ratio of the adhesive resin is too high, the hardening required for the manifestation of high bonding strength becomes insufficient, and if it is too low, the workability before hardening is improved, but the strength required for bonding is sometimes reduced.

As the bonding material (X), it is preferred to use one that is pre-formed into any shape such as a sheet as described above. In order to improve the working efficiency when forming the composition containing the polymerizable compound into the sheet, it is preferred to use one that contains a solvent in addition to the polymerizable compound or the polymerization initiator.

As the solvent, for example, ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; aromatic hydrocarbon solvents such as toluene and xylene, etc. can be used.

In addition, as the bonding material (X), those containing other components can be used. As the other components, for example, fillers such as aluminum hydroxide, aluminum oxide, aluminum nitride, magnesium hydroxide, magnesium oxide, mica, talc, boron nitride, and glass flakes can be used.

In addition, as the bonding material (X), in addition to the above-mentioned ones, additives such as fillers, softeners, stabilizers, adhesion promoters, leveling agents, defoaming agents, plasticizers, adhesive resins, fibers, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, thickeners, pigments and other coloring agents may also be used within the scope that does not impair the effects of the present invention.

The bonding material (X) of the present invention can be produced by mixing the polymerizable compound with any component such as the polymerization initiator or solvent.

When mixing the above components to produce the bonding material (X), a dissolver, butterfly mixer, BDM double-shaft mixer, planetary mixer, etc. may be used as needed. Dissolvers and butterfly mixers are preferred. When the above conductive fillers are used, a planetary mixer is preferred in terms of improving the dispersibility of the fillers.

Furthermore, the polymerization initiator is preferably used before the bonding material (X) is hardened or formed into a sheet, etc.

In addition, the sheet-shaped bonding material can be manufactured, for example, by manufacturing a composition containing the polymerizable compound and any components such as the polymerization initiator or solvent, and then applying the composition to the surface of a release liner and drying the composition.

Regarding the drying, in order to suppress the hardening reaction of the sheet-shaped bonding material, it is suitable to be carried out at a temperature of preferably 40°C to 120°C, more preferably 50°C to 90°C. In addition, it is preferable because it can suppress the foaming of the sheet surface caused by the rapid volatilization of the solvent, etc.

The sheet-shaped bonding material may also be clamped by the peeling pad before use.

As the peeling pad, for example, kraft paper, glassine paper, woodfree paper, etc. can be used; resin films such as polyethylene, polypropylene (oriented polypropylene (OPP), cast polypropylene (CPP)), polyethylene terephthalate, etc.; laminated paper with the above paper and resin film, paper filled with clay or polyvinyl alcohol, etc., and peeling treatment with silicone resin, etc., is applied to one or both sides of the paper, etc.

The laminate of the present invention is relatively soft before hardening, so it has excellent step tracking performance for the adherend, and becomes very hard after hardening, so it can fully bond the adherend. Therefore, it can be used in materials that firmly bond various components specifically used for image display devices.

As the image display device, for example, there can be listed the components of a flat image display device using an image display panel equipped with a liquid crystal display (LCD), plasma display (PDP) or electroluminescent (EL), organic EL, light emitting diode (LED), quantum dot (QD), etc., such as a mobile terminal (Personal Digital Assistant (PDA)), game console, television (TV), car navigation, touch panel, digital drawing tablet, etc. As the components, for example, there can be listed the image display panel, circuit substrate, rear cover, frame, frame, chassis, etc.

[Implementation example]

The following is a detailed description of the implementation examples and comparative examples.

<Preparation of acrylic copolymer (1)>

Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen inlet, 25 parts by mass of n-butyl acrylate, 80 parts by mass of 2-methoxyethyl acrylate, 1 part by mass of 2-hydroxyethyl acrylate and 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and after nitrogen substitution, polymerization was carried out at 80°C for 8 hours to obtain an acrylic copolymer (1) with a solid content of 50% by mass and a weight average molecular weight of 750,000. The glass transition temperature was -25°C.

<Preparation of polyurethane (1)>

In a reaction vessel, 50 parts by mass of aliphatic polycarbonate polyol with a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate and 30 parts by mass of polyester polyol with a number average molecular weight of 4500 obtained by reacting 1,6-hexanediol and adipic acid were mixed, and heated to 100°C under reduced pressure to dehydrate until the moisture content reached 0.05% by mass.

Next, the mixture of the aliphatic polycarbonate polyol and the polyester polyol was cooled to 70°C and mixed with 14.5 parts by weight of dicyclohexylmethane-4,4'-diisocyanate, and then heated to 100°C and reacted for 3 hours. Thereafter, methyl ethyl ketone was prepared in such a manner that the solid content was 50% by weight, thereby obtaining polyurethane (1). The glass transition temperature was -28°C.

<Preparation of bonding material (A-1)>

EX-321L (manufactured by Nagase Chemtex, a trihydroxymethylpropane polyglycidyl ether type epoxy resin) 50 parts by mass, the acrylic copolymer (1) 100 parts by mass, CPI-100P (manufactured by San-Apro, a coronium salt system) 2 parts by mass, and BURNOCK DN980 (manufactured by DIC Corporation, a hexamethylene diisocyanate type isocyanate crosslinking agent) 0.20 parts by mass were mixed to obtain an adhesive resin coating (a-1).

Next, the bonding resin coating (a-1) was applied to the surface of a release liner (a polyethylene terephthalate film having a thickness of 75 μm and subjected to a release treatment on one side with a silicone compound) using a rod-shaped metal applicator so that the thickness after drying was 100 μm.

Furthermore, the coating was placed in a dryer at 85°C for 5 minutes for drying, and a release liner (one side of a 38μm thick polyethylene terephthalate film subjected to a release treatment using a silicone compound) was attached to one side of the dried coating. After that, the coating was aged at 40°C for 72 hours to obtain a sheet-shaped bonding material (A-1) with a thickness of 100μm.

Furthermore, the bonding material (A-1) has a photopolymerization initiator and an epoxy group as a reaction site, so the curing reaction of the epoxy group can be activated by irradiating light.

The bonding material (A-1) had a storage elastic coefficient of 1.7×10 ⁴ Pa at 23°C and a storage elastic coefficient of 2.9×10 ³ Pa at 70°C.

Furthermore, the storage elastic coefficient of the bonding material (A-1) at 23°C and 70°C was calculated by sandwiching the test piece between parallel disks as the measuring part of the same tester using a dynamic viscoelastic tester (manufactured by Rheometrics, trade name: ARES 2KSTD) and measuring at a heating rate of 3°C/min, a measuring frequency of 1.0 Hz, and a measuring temperature range of 0°C to 200°C. As the test piece used in the measurement, a test piece was used that was laminated to a thickness of 1mm after removing the peeling pad on one side of the bonding material (A-1) and cut into a circular shape including a diameter of 8mm.

<Preparation of bonding material (A-2)>

The bonding resin coating (a-2) and bonding material (A-2) were obtained by the same method as the preparation of the bonding material (A-1), except that CEL-2021P (manufactured by Daicel Corporation, epoxy resin) was used instead of 50 parts by mass of EX-321L (manufactured by Nagase Chemtex Corporation, trihydroxymethylpropane polyglycidyl ether type epoxy resin).

Furthermore, the bonding material (A-2) has a photopolymerization initiator and an epoxy group as a reaction site, so the curing reaction of the epoxy group can be activated by irradiating light.

The bonding material (A-2) had a storage elastic coefficient of 9.3×10 ³ Pa at 23°C and a storage elastic coefficient of 1.0×10 ³ Pa at 70°C.

<Preparation of bonding material (A-3)>

The bonding resin coating (a-3) and bonding material (A-3) were obtained by the same method as the preparation of the bonding material (A-1), except that 2.0 parts by mass of DICY-7 (dicyandiamide, manufactured by Mitsubishi Chemical Co., Ltd.) was used instead of CPI-100P.

Furthermore, the bonding material (A-3) has a thermal polymerization initiator and an epoxy group as a reaction site, so the curing reaction of the epoxy group can be activated by heating.

The bonding material (A-3) had a storage elastic coefficient of 9.6×10 ³ Pa at 23°C and a storage elastic coefficient of 1.0×10 ³ Pa at 70°C.

As the adherend used in this embodiment and the comparative example, a smooth surface aluminum plate with a thickness of 0.05 mm was cut into a width of 15 mm × a length of 150 mm, and it was set as the adherend (I). In addition, a smooth surface epoxy glass plate with a thickness of 1.0 mm (manufactured by Shin Kobe Electric Co., Ltd./KEL-GEF) was cut into a width of 15 mm × a length of 150 mm, and it was set as the adherend (II). Furthermore, the adherend (I) and the adherend (II) are opaque materials.

<Preparation of bonding material (A-4)>

Adhesive resin coating (a-4) and bonding material (A-4) were obtained by the same method as the preparation of bonding material (A-1), except that 100 parts by mass of polyurethane (1) was used instead of acrylic copolymer (1), the amount of CEL-2021P (manufactured by Daicel, epoxide resin) was changed from 50 parts by mass to 21 parts by mass, the amount of CPI-100P (manufactured by San-Apro, coronium salt system, solid content concentration 50%) was changed from 2 parts by mass to 2.9 parts by mass, and the amount of BURNOCK DN980 (manufactured by DIC Corporation, hexamethylene diisocyanate type isocyanate crosslinking agent) was changed from 0.20 parts by mass to 0 parts by mass.

Furthermore, the bonding material (A-4) has a photopolymerization initiator and an epoxy group as a reaction site, so the curing reaction of the epoxy group can be activated by irradiating light.

The bonding material (A-4) had a storage elastic coefficient of 4.9×10 ⁴ Pa at 23° C. and a storage elastic coefficient of 1.2×10 ¹ Pa at 70° C.

(Implementation Example 1)

The bonding material (A-1) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and attached to the adherend (I) at 23°C.

With 1 kg loaded on the attached object, place it in a 70°C environment for 30 minutes.

After the above-mentioned placement, the 1 kg load was removed from the attached object and placed in an environment of 23°C for 30 minutes. Thereafter, the peeling pad was removed from the other side of the test sample, and the surface of the exposed bonding material was irradiated with 250 mJ/ ^cm2 of ultraviolet light using an electrodeless lamp (fusion lamp H valve).

After the irradiation, place at 23°C for 2 minutes, attach the adherend (II) to the surface of the irradiated bonding material layer, and use a hot pressing device heated to 40°C to perform press bonding for 10 seconds at a pressure of 0.5MPa.

The laminated body after pressing and bonding was heated at 70°C for 1 hour, placed in a 23°C environment for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X-1).

The time required for the preparation of the evaluation sample (X-1) is 2 hours, 32 minutes and 10 seconds. In addition, the time required for the hardening of the evaluation sample (X-1) is 1 hour.

In the evaluation sample (X-1), the ends of the adherend (I) and the adherend (II) are chucking, and a tensile tester is used to perform a tensile test in a 180-degree direction at a tensile speed of 10 mm/min, thereby obtaining the shear adhesion of the evaluation sample (X-1). At this time, the shear adhesion of the evaluation sample (X-1) is 920 Pa.

The storage elastic modulus at 25°C of the cured product (B-1) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X-1) was 5.7×10 ⁵ Pa.

In addition, the storage elastic coefficient of the cured product (B-1) of the sheet-shaped bonding material (A-1) at 25°C was measured using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, RSA III) at a heating rate of 3°C/min, a measuring frequency of 1.0 Hz, and a measuring temperature range of 0°C to 200°C, and the storage elastic coefficient (G') at 25°C and 100°C was calculated respectively.

(Example 2)

The bonding material (A-1) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and attached to the adherend (I) at 23°C.

The adhered article was placed in an environment of 23°C for 30 minutes. Thereafter, the peeling pad was removed from the other side of the test sample, and the exposed surface of the bonding material was irradiated with ultraviolet light of 250 mJ/ ^cm2 using an electrodeless lamp (fusion lamp H valve).

After the irradiation, place at 23°C for 2 minutes, attach the adherend (II) to the surface of the irradiated bonding material layer, and use a hot pressing device heated to 40°C to perform press bonding for 10 seconds at a pressure of 0.5MPa.

The laminated body after pressing and bonding was heated at 70°C for 1 hour, placed in a 23°C environment for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X-2).

The time required to prepare the evaluation sample (X-2) is 2 hours, 2 minutes and 10 seconds. In addition, the time required to harden the evaluation sample (X-2) is 1 hour.

The shear adhesion of the evaluation sample (X-2) was calculated using the same method as in Example 1. The shear adhesion of the evaluation sample (X-2) at this time was 880 Pa.

The storage elastic modulus at 25°C of the cured product (B-2) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X-2) was 4.9×10 ⁵ Pa.

(Implementation Example 3)

Except for using the bonding material (A-2), the evaluation sample (X-3) was prepared using the same method as Example 1.

The time required for the preparation of the evaluation sample (X-3) is 2 hours, 32 minutes and 10 seconds. In addition, the time required for the hardening of the evaluation sample (X-3) is 1 hour.

The shear adhesion of the evaluation sample (X-3) was calculated using the same method as in Example 1. At this time, the shear adhesion of the evaluation sample (X-3) was 1100 Pa.

The storage elastic modulus at 25°C of the cured product (B-3) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X-3) was 6.3×10 ⁶ Pa.

(Implementation Example 4)

An evaluation sample (X-4) was prepared in the same manner as in Example 1 except that the bonding material (A-4) was used and the ultraviolet irradiation dose using an electrodeless lamp (fusion lamp H valve) was changed from 250 mJ/cm ² to 500 mJ/cm ² .

The time required for the preparation of the evaluation sample (X-4) is 2 hours, 32 minutes and 10 seconds. In addition, the time required for the hardening of the evaluation sample (X-4) is 1 hour.

The shear adhesion strength of the evaluation sample (X-4) was calculated using the same method as in Example 1. At this time, the shear adhesion strength of the evaluation sample (X-4) was 3700 Pa.

The storage elastic modulus at 25°C of the cured product (B-4) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X-4) was 5.8×10 ⁸ Pa.

(Example 5)

The bonding material (A-4) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and attached to the adherend (I) at 23°C.

Thereafter, the adhered article was placed in an environment of 23°C for 30 minutes. Thereafter, the peeling pad was removed from the other side of the test sample, and the exposed surface of the bonding material was irradiated with ultraviolet light at 500 mJ/ ^cm2 using an electrodeless lamp (fusion lamp H valve).

After the irradiation, place at 23°C for 2 minutes, attach the adherend (II) to the surface of the irradiated bonding material layer, and use a hot pressing device heated to 40°C to perform press bonding for 10 seconds at a pressure of 0.5MPa.

Afterwards, the attached object was loaded with 1 kg and placed in a 70°C environment for 5 minutes.

After the placement, the 1 kg load was removed from the attached object, heated at 70°C for 55 minutes, placed in a 23°C environment for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X-5).

The time required to prepare the evaluation sample (X-5) is 2 hours, 2 minutes and 10 seconds. In addition, the time required to harden the evaluation sample (X-5) is 1 hour.

The shear adhesion strength of the evaluation sample (X-5) was calculated using the same method as in Example 1. At this time, the shear adhesion strength of the evaluation sample (X-5) was 3500 Pa.

The storage elastic modulus at 25°C of the cured product (B-5) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X-5) was 4.3×10 ⁸ Pa.

(Comparison Example 1)

The bonding material (A-1) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and the adherend (I) is attached.

With 1 kg loaded on the attached object, place it in a 70°C environment for 30 minutes.

After the placement, the 1kg load is removed from the attached object and placed in an environment of 23°C for 30 minutes. Thereafter, the peeling pad is removed from the other side of the test sample, and the adherend (II) is attached to the surface of the irradiated bonding material layer, and a hot press device heated to 40°C is used to perform press bonding for 10 seconds under a pressure of 0.5MPa.

After the crimping, 250 mJ/ ^cm2 of ultraviolet light is irradiated from the adhered object (I) side using an electrodeless lamp (fusion lamp H valve).

The irradiated laminate was heated at 70°C for 1 hour, placed in a 23°C environment for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X'-1).

The time required for the preparation of the evaluation sample (X'-1) is 2 hours, 30 minutes and 10 seconds. In addition, the time required for the hardening of the evaluation sample (X'-1) is 1 hour.

The shear adhesion of the evaluation sample (X'-1) was calculated using the same method as in Example 1. The shear adhesion of the evaluation sample (X'-1) was 40 Pa at this time.

The storage elastic modulus at 25° C. of the cured product (B′-1) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X′-1) was 1.7×10 ⁴ Pa.

(Comparison Example 2)

The bonding material (A-1) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and the adherend (I) is attached.

The adhered object was placed in an environment of 23°C for 30 minutes. Afterwards, the peeling pad was removed from the other side of the test sample, and the adherend (II) was attached to the surface of the irradiated bonding material layer, and a hot press device heated to 40°C was used to perform press bonding for 10 seconds under a pressure of 0.5MPa.

After the crimping, 250 mJ/ ^cm2 of ultraviolet light was irradiated from the adhered object (II) side using an electrodeless lamp (fusion lamp H valve).

The irradiated laminate was heated at 70°C for 1 hour, placed in a 23°C environment for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X'-2).

The time required for the preparation of the evaluation sample (X'-2) is 2 hours and 10 seconds. In addition, the time required for the hardening of the evaluation sample (X'-2) is 1 hour.

The shear adhesion of the evaluation sample (X'-2) was calculated using the same method as in Example 1. The shear adhesion of the evaluation sample (X'-2) at this time was 38 Pa.

The storage elastic modulus at 25°C of the cured product (B'-2) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X'-2) was 1.7×10 ⁴ Pa.

(Comparison Example 3)

The bonding material (A-3) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and the adherend (I) is attached.

With 1 kg loaded on the attached object, place it in a 70°C environment for 30 minutes.

After the placement, the 1kg load is removed from the attached object and placed in an environment of 23°C for 30 minutes. Thereafter, the peeling pad is removed from the other side of the test sample, and the adherend (II) is attached to the surface of the irradiated bonding material layer, and a hot press device heated to 40°C is used to perform press bonding for 10 seconds under a pressure of 0.5MPa.

The pressurized laminate was heated at 180°C for 1 hour, placed in a 23°C environment for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X'-3).

The total time required for the preparation of the evaluation sample (X'-3) was 2 hours, 30 minutes and 10 seconds. In addition, the time required for the hardening of the evaluation sample (X'-3) was 1 hour. By visually checking the evaluation sample (X'-3), it was found that the adhesive (II) was deteriorated and changed color to yellow.

The shear adhesion of the evaluation sample (X'-3) was calculated using the same method as in Example 1. The shear adhesion of the evaluation sample (X'-3) at this time was 203Pa.

The storage elastic modulus at 25° C. of the cured product (B′-3) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X′-3) was 7.5×10 ⁶ Pa.

(Comparison Example 4)

The bonding material (A-3) is cut into a size of 10 mm in width x 10 mm in length and used as a test sample. One of the peeling pads of the test sample is removed and the adherend (I) is attached.

With 1 kg loaded on the attached object, place it in a 70°C environment for 30 minutes.

After the placement, the 1kg load is removed from the attached object and placed in an environment of 23°C for 30 minutes. Thereafter, the peeling pad is removed from the other side of the test sample, and the adherend (II) is attached to the surface of the irradiated bonding material layer, and a hot press device heated to 40°C is used to perform press bonding for 10 seconds under a pressure of 0.5MPa.

The pressurized laminate was heated at 70°C for 3 hours, placed at 23°C for 30 minutes and cooled, and the obtained product was set as the evaluation sample (X'-4).

The time required to prepare the evaluation sample (X'-4) is 4 hours, 30 minutes and 10 seconds. In addition, the time required to harden the evaluation sample (X'-4) is 3 hours.

The shear adhesion of the evaluation sample (X'-4) was calculated using the same method as in Example 1. The shear adhesion of the evaluation sample (X'-4) at this time was 115 Pa.

The storage elastic modulus at 25°C of the cured product (B'-4) of the sheet-shaped bonding material (A-1) obtained by the same curing method as that of the evaluation sample (X'-4) was 6.5×10 ⁴ Pa.

According to the above results, in Examples 1 to 5, a laminate can be made in a short time and at a low temperature, and sufficient bonding can be obtained even for an opaque adherend. On the other hand, in Comparative Examples 1 to 2, although the laminate is made in a short time and at a low temperature, the bonding material does not harden and sufficient bonding cannot be obtained. In addition, in Comparative Example 3, although bonding can be obtained in a short time, high temperature is required for hardening, so degradation of the adherend is observed. In Comparative Example 4, although bonding can be obtained at a low temperature, a lot of time is required.

Claims (7)

A method for manufacturing a laminate containing a hardening bonding material, wherein the laminate comprises a bonded body (C1) and a bonded body (C2) separated by a bonding material (X), the method comprising: step [01] of attaching the bonding material (X) to the bonded body (C2); step [1] of activating the reaction site of the bonding material (X) by irradiating light; step [2] of attaching the bonding material (X) to the bonded body (C1); and step [3] of activating the bonded body (C2). The bonding material (X) is hardened, and at least one of the steps [01] and [1] and between the steps [2] and [3] includes a step [02], wherein the step [02] is a curing step for performing step-following, and the step [3] includes a heating step, wherein the bonding material (X) comprises an acrylic copolymer or a polyurethane, an epoxy resin, and a photo-cationic polymerization initiator, and the storage elastic coefficient of the bonding material (X) at 25°C after the step [3] is greater than 1.0×10 ⁵ Pa. A method for manufacturing a laminate containing a hardening bonding material as described in Item 1 of the patent application, wherein the step [02] includes a heating step. A method for manufacturing a laminate containing a hardening bonding material as described in item 1 or 2 of the patent application, wherein at least one of step [2] and step [01] includes a heating step. The method for manufacturing a laminate containing a hardenable bonding material as described in claim 1 or 2, wherein in step [01], the storage elastic coefficient of the bonding material (X) during bonding is greater than 5.0×10 ³ Pa; and in step [02], the storage elastic coefficient of the bonding material (X) during step tracking is less than 5.0×10 ³ Pa. A method for manufacturing a laminate containing a hardening bonding material as described in item 1 or 2 of the patent application, wherein the bonding material (X) is in sheet form. A method for manufacturing a laminate containing a curable bonding material as described in item 1 or 2 of the patent application, wherein the weight average molecular weight of the acrylic copolymer or polyurethane is 2000~2000000. A method for manufacturing a laminate containing a hardening bonding material as described in item 1 or 2 of the patent application scope, wherein the laminate is used for an image display device.