JP7306014B2 - Curable adhesive composition, adhesive sheet using the same, laminate containing the adhesive sheet, and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bonding material that can be used for laminating adherends through which active energy rays are difficult to pass.

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, and the like.
The liquid crystal display device generally includes a liquid crystal display panel, a planar illumination device (backlight device) arranged on the back surface of the liquid crystal display panel to illuminate the liquid crystal display panel, a circuit board (substrate) and other electronic parts. It is known to have a structure in which members such as a chassis on which the components are mounted and a heat sink for diffusing heat generated from the components are laminated.

In order to laminate the members of the liquid crystal display device, for example, when the surface of the member to be laminated has flexure or unevenness, an adhesive is applied, and after the adhesive is made to follow the flexure or unevenness, the thickness of the coated surface is In order to remove unevenness, a method of smoothing the surface coated with the adhesive by squeegeeing the applied adhesive and then laminating another member is often used (see, for example, Patent Document 1).
However, in the lamination process described above, it is necessary to control the amount of adhesive applied, and the cleaning process after application takes time.

Against this background, in recent years, instead of adhesives, the use of adhesive sheets with excellent step conformability has been proposed (see, for example, Patent Document 2). The adhesive sheet having excellent step conformability can prevent the pressure-sensitive adhesive component from being extruded from the end of the roll even when it is wound on a roll or the like and stored, and can be processed into any size. It is possible to eliminate the need for controlling the coating amount in the lamination process and the washing process. In addition, when the adhesive sheet having excellent step followability is irradiated with light as an external stimulus, the polymerization reaction proceeds to form a cured product, and members can be joined via the cured product of the adhesive sheet. .

However, the adhesive sheet having excellent step conformability proceeds rapidly immediately after being irradiated with light, and the flexibility necessary for bonding is impaired. It was necessary to irradiate light after laminating the adhesive sheet and the members. As a result, it was not possible to bond members that could not transmit light, and the applicable members were limited.

JP 2003-136677 A JP 2015-120773 A

The problem to be solved by the present invention is that, when used as an adhesive sheet, it is possible to prevent the pressure-sensitive adhesive component from being extruded from the end of the roll even when it is wound up on a roll or the like and stored, and Another object of the present invention is to provide a curable adhesive composition capable of following a stepped portion on the surface of a non-light-transmitting member and curing the same. Further, when an adhesive layer is formed using the curable adhesive composition to produce an adhesive sheet having the adhesive layer, the adhesive sheet is wound on a roll or the like and stored. Another object of the present invention is to provide a curable adhesive composition capable of preventing the adhesive layer from being extruded from the end of the roll.

The present inventors solved the problem by using a curable adhesive composition containing a polyurethane (A) having a polymerizable functional group other than a polymerizable unsaturated double bond having the specific storage modulus. found to be able to solve
That is, the present invention relates to a curable adhesive composition used for bonding two or more adherends having surfaces that do not transmit active energy rays, wherein the curable adhesive composition comprises a polymerizable unsaturated di It contains a polyurethane (A) having a polymerizable functional group other than a heavy bond, and the curable adhesive composition has a loss tangent (tan δ ₄₀ ) at 40°C of less than 3.0 and a loss tangent (tan δ ₆₀ ) is 1.0 or more.

Since the curable adhesive composition of the present invention has the flexibility necessary for bonding even after applying an external stimulus, it is possible to bond and laminate adherends after applying an external stimulus. is. In addition, the curable adhesive composition of the present invention, for example, when light is used as an external stimulus, has the flexibility necessary for bonding even after irradiation with light, and can bond even members that cannot transmit light. Is possible.
Since the curable adhesive composition of the present invention has the flexibility necessary for bonding even after applying an external stimulus, it is possible to apply an external stimulus to an adherend having a warped or uneven surface. It is possible to allow the curable adhesive composition to follow.

The adhesive sheet using the curable adhesive composition of the present invention as an adhesive layer suppresses extrusion of the adhesive layer even when stored in a state of being wound on a roll or the like. can be done. In addition, even when the adhesive sheet is wound on a roll or the like and stored, the adhesive component can be prevented from being pushed out from the end of the roll. Since it is possible to follow, for example, a liquid crystal display panel, a planar lighting device (backlight device) that is arranged on the back of the liquid crystal display panel and illuminates the liquid crystal display panel, a circuit board (substrate), and other electronic parts It can be used for stacking members such as heat sinks for diffusing heat generated from mounted chassis and components.
When the curable adhesive composition of the present invention is used to form an adhesive layer to produce an adhesive sheet having the adhesive layer, the adhesive sheet is wound on a roll or the like and stored. Even if it is, the adhesive layer can be prevented from being extruded from the end of the roll.

The curable adhesive composition of the present invention is used for bonding two or more adherends having surfaces that do not transmit active energy rays, and the curable adhesive composition comprises a polymerizable unsaturated di It contains a polyurethane (A) having a polymerizable functional group other than a heavy bond, and the curable adhesive composition has a loss tangent (tan δ ₄₀ ) at 40°C of less than 3.0 and a loss tangent (tan δ ₆₀ ) is 1.0 or more.

The curable adhesive composition of the present invention is excellent in handleability before curing, and the thickness can be easily adjusted. preferably.

The polyurethane (A) contained in the curable adhesive composition has polymerizable functional groups other than polymerizable unsaturated double bonds. As a result, it is possible to suppress a rapid curing reaction after applying an external stimulus and allow the curing reaction to progress gradually, so that even after applying an external stimulus, it is possible to have the flexibility necessary for bonding. As a result, it is possible to laminate the adhesive sheet and the members together after applying an external stimulus.

If the adhesive sheet has an adhesive layer using the curable adhesive composition, for example, when light is used as an external stimulus, curing proceeds gradually after light irradiation, so even after light irradiation It has the flexibility necessary for bonding, and can be bonded even to members that do not transmit light. In addition, the adhesive sheet of the present invention can prevent the adhesive layer from being pushed out from the end of the roll even when the adhesive sheet is wound on a roll or the like and stored. It is possible to follow the stepped part of the surface and the surface.

In addition, the loss tangent (tan δ ₄₀ ) at 40° C. and the loss tangent (tan δ ₆₀ ) at 60° C. of the curable adhesive composition were obtained from the components of the curable adhesive composition, specifically the polyurethane (A). can be set within the predetermined range by appropriately selecting the composition and number average molecular weight of the polyol (a1) that constitutes the above.

In addition, the loss tangent at 40°C (tan δ ₄₀ ) and the loss tangent at 60°C (tan δ ₆₀ ) are the other components of the curable adhesive composition, specifically the polymerizable compound (B) described below, and others. By appropriately blending additives, etc., the content can be set within the aforementioned predetermined range.

The curable adhesive composition has a loss tangent (tan δ ₄₀ ) at 40° C. of less than 3.0 when measured at a frequency of 1 Hz. It is preferable to prevent the adhesive layer from being pushed out from the end of the roll even when it is wound up and stored, and to improve the flexibility of the member and the followability to the stepped surface. It is more preferably in the range of 0.01 or more to 1.5 or less, more preferably in the range of 0.1 or more to 1.0 or less, and 0.1 or more to 0.8 or less It is particularly preferred to use a range. By setting the above range, even when the adhesive sheet is wound on a roll or the like and stored, the adhesive layer is further prevented from being extruded from the end of the roll, and the handleability before curing is improved. It is possible to obtain an adhesive sheet excellent in

The curable adhesive composition has a loss tangent (tan δ ₆₀ ) at 60° C. of 1.0 or more when measured at a frequency of 1 Hz, more preferably 3.0 or more, and 5.0 or more. It is more preferably 10.0 or more in order to obtain an adhesive sheet with further improved conformability to the bending of the member and the stepped portion of the surface.

The loss tangent (tan δ ₄₀ ) at 40°C and the loss tangent (tan δ ₆₀ ) at 60°C were measured using a dynamic viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD). A test piece is sandwiched between parallel discs, which are the measurement parts, and the storage elastic modulus (G') and loss elastic modulus (G") are measured at a temperature of 40 ° C. or 60 ° C. and a frequency of 1 Hz, and the loss tangent (tan δ ) is the value (G″/G′) obtained by dividing the loss elastic modulus (G″) by the storage elastic modulus (G′). An adhesive layer using the composition was cut into a circle having a thickness of 1 mm and a diameter of 8 mm.

The curable adhesive composition preferably has a melting point in the range of 25°C to 120°C, more preferably 30°C to 90°C, and more preferably 35°C to 60°C. Even when an adhesive sheet having an adhesive layer using the curable adhesive composition is wound on a roll or the like and stored, the adhesive layer does not spread from the end of the roll. It is more preferable for obtaining an adhesive sheet which can be further prevented from being extruded and has improved conformability to bending of members and stepped portions on the surface.

The melting point is defined as the temperature rising from 30° C. to 150° C. at a temperature rising rate of 10° C./min using differential scanning calorimetry (DSC method), holding for 1 minute, and then reaching 10° C. It refers to the temperature showing the maximum exothermic peak (exothermic peak top) observed when the temperature is once cooled to −10° C. under the condition of temperature decrease at 10° C./min, held for 10 minutes, and then measured again under the condition of temperature increase of 10° C./min. .

As the curable adhesive composition, one containing a polyurethane (A) having a polymerizable functional group other than a polymerizable unsaturated double bond is used.

By using the polyurethane (A) having a polymerizable functional group other than the polymerizable unsaturated double bond, it is possible to suppress a rapid curing reaction after applying an external stimulus and to allow the curing reaction to proceed gradually. Therefore, it is possible to have the flexibility necessary for bonding even after applying an external stimulus. As a result, when an adhesive layer is formed using the curable adhesive composition, it is possible to laminate the adhesive layer and members after applying an external stimulus.

As the polyurethane (A) having a polymerizable functional group other than the polymerizable unsaturated double bond, for example, when the polymerization reaction is advanced by light irradiation as an external stimulus, not only polymerization by light irradiation but also dark reaction Since the polymerization can also proceed, for example, it is possible to join members that do not transmit light.

The polyurethane (A) preferably has, as a polymerizable functional group other than the polymerizable unsaturated double bond, at least one selected from the group consisting of an isocyanate group, a hydroxyl group, an oxetanyl group and an epoxy group. By using the polyurethane (A′) having at least one selected from the group consisting of the isocyanate group, hydroxyl group, oxetanyl group and epoxy group, rapid curing reaction after application of an external stimulus is suppressed, and the curing reaction is suppressed. can be progressed gradually, the flexibility required for bonding can be maintained even after the application of an external stimulus. As a result, it is possible to laminate the adhesive layer and the member together after applying an external stimulus.

As the polyurethane (A') having an isocyanate group, for example, a polyurethane (A'1) having an isocyanate group obtained by reacting a polyol (a'1) and a polyisocyanate (a'2) is used. be able to.

As the polyurethane (A') having a hydroxyl group, for example, a polyurethane (A'2) having a hydroxyl group obtained by reacting a polyol (a'1) and a polyisocyanate (a'2) can be used. can.

Examples of the polyurethane (A') having an oxetanyl group or an epoxy group include: 1) the polyurethane (A'1) having an isocyanate group;
2) reacting a functional group (a''1) reactive with the isocyanate group with a monomer (A'') having at least one polymerizable functional group (a''2) of an oxetanyl group or an epoxy group; Polyurethanes (A'3) can be used which are obtained by

As the functional group (a″1) capable of reacting with the isocyanate group, for example, a hydroxyl group, an amino group, a carboxyl group, a mercapto group and the like can be used, and it is preferable to use a hydroxyl group and an amino group.

The polymerizable functional group (a″2) other than the polymerizable unsaturated double bond refers to a functional group other than a functional group having so-called radical polymerizability, for example, a functional group having cationic polymerizability and an anion polymerizability. A functional group.

As the polymerizable functional group (a″2) other than the polymerizable unsaturated double bond, for example, an epoxy group, an oxetanyl group, an ethylene sulfide group, etc. can be used, and an oxetanyl group is preferably used. .

The monomer (A″) has a functional group (a″1) capable of reacting with the isocyanate group and at least one polymerizable functional group (a″2) of an oxetanyl group or an epoxy group. It is not particularly limited as long as it contains 3-ethyl-3-(4-hydroxybutyl)oxymethyl-oxetane, 3-hydroxymethyl-3-ethyloxetane, 2-hydroxymethyloxetane, 3-hydroxy oxetane and the like.

The monomer (A″) is preferably used in the range of 5 parts by mass to 20 parts by mass with respect to 100 parts by mass of the polyurethane (A′), and in the range of 5 parts by mass to 15 parts by mass. It is more preferable to use

More specifically, the monomer (A″) preferably exceeds 50 mol % and is 100 mol % or less, more preferably 60 mol %, based on the number of moles of isocyanate groups possessed by the polyurethane (A′). mol % to 100 mol %, more preferably 80 mol % to 100 mol %, can be used in an amount capable of supplying the functional group capable of reacting with the isocyanate group. A polyurethane excellent in curability, shape retention after application to a substrate, mechanical strength, durability (especially hydrolysis resistance), adhesion to a substrate, and the like can be obtained.

When the polyurethane (A′) and the monomer (A″) are reacted, a urethanization catalyst can be used as necessary. The urethanization reaction is preferably carried out until the isocyanate group content (%) becomes substantially constant.

Examples of the urethanization catalyst include nitrogen-containing compounds such as triethylamine, triethylenediamine and N-methylmorpholine; organometallic salts such as potassium acetate, zinc stearate and stannous octylate; and organometallic compounds such as dibutyltin dilaurate. etc. can be used.

The polyurethane (A) preferably has a loss tangent (tan δ ₄₀ ) at 40°C of less than 3.0 and a loss tangent (tan δ ₆₀ ) at 60°C of 1.0 or more.

Further, the loss tangent (tan δ ₄₀ ) at 40° C. and the loss tangent (tan δ ₆₀ ) at 60° C. of the polyurethane (A) are the components of the polyurethane (A), specifically the polyols constituting the polyurethane (A). By appropriately selecting the composition of (a'1), its number average molecular weight, etc., it can be set within the aforementioned predetermined range.

As the polyurethane (A), the loss tangent (tan δ ₄₀ ) of the polyurethane (A) at 40°C is less than 3.0 when measured at a frequency of 1 Hz. Even when the adhesive sheet is wound on a roll or the like and stored, the adhesive layer can be prevented from being pushed out from the end of the roll, and the conformability to the bending of the member and the stepped portion of the surface can be improved. preferably in the range of 0.01 to 1.5, more preferably in the range of 0.1 to 1.0, and more preferably in the range of 0.1 to 0.1. It is particularly preferred to use those in the range of 8 or less. By setting the above range, even when an adhesive sheet having an adhesive layer using the curable adhesive composition containing the polyurethane (A) is wound on a roll or the like and stored, the adhesive layer is further prevented from being extruded from the end of the roll, and an adhesive sheet having excellent handleability before curing can be obtained.

As the polyurethane (A), use of one having a loss tangent (tan δ ₆₀ ) at 60° C. of 1.0 or more when measured at a frequency of 1 Hz is excellent in handleability before curing, and the polyurethane (A ) to prevent the adhesive layer from being extruded from the end of the roll even when an adhesive sheet having an adhesive layer using a curable adhesive composition containing is wound up on a roll or the like and stored In addition, it is preferable to improve the bending of the member and the followability to the stepped portion of the surface. More preferably, it is 10.0 or more to obtain an adhesive sheet with further improved conformability to the deflection of the member and the stepped portion of the surface.

The loss tangent (tan δ ₄₀ ) at 40°C and the loss tangent (tan δ ₆₀ ) at 60°C were measured using a dynamic viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD). A test piece is sandwiched between parallel discs, which are the measurement parts, and the storage elastic modulus (G') and loss elastic modulus (G") are measured at a temperature of 40 ° C. or 60 ° C. and a frequency of 1 Hz, and the loss tangent (tan δ ) is the value (G″/G′) obtained by dividing the loss modulus (G″) by the storage modulus (G′). was cut into a circle having a thickness of 1 mm and a diameter of 8 mm.

The polyurethane (A) preferably has a melting point in the range of 25°C to 120°C, more preferably 30°C to 90°C, more preferably 35°C to 60°C. An adhesive sheet having an adhesive layer using the curable adhesive composition containing the polyurethane (A) is wound on a roll or the like and stored even if the adhesive layer has a melting point of It is further preferable for obtaining an adhesive sheet which can further prevent the extrusion of the shavings from the end of the roll and further improve the conformability to the bending of the member and the stepped portion of the surface.

The melting point is defined as the temperature rising from 30° C. to 150° C. at a temperature rising rate of 10° C./min using differential scanning calorimetry (DSC method), holding for 1 minute, and then reaching 10° C. It refers to the temperature showing the maximum exothermic peak (exothermic peak top) observed when the temperature is once cooled to −10° C. under the condition of temperature decrease at 10° C./min, held for 10 minutes, and then measured again under the condition of temperature increase of 10° C./min. .

As the polyol (a'1) that can be used for producing the polyurethane (A), one or more selected from the group consisting of polycarbonate polyols, polyester polyols, and polyether polyols can be used. Among them, as the polyol (a′1), it is preferable to use a polycarbonate polyol or a polyester polyol alone or in combination of two or more kinds. Excellent handleability, for example, an adhesive sheet having an adhesive layer using the curable adhesive composition containing the polyurethane (A ') is wound on a roll or the like, and even when it is stored, the adhesive This is more preferable because it is possible to further prevent the layer from being extruded from the end of the roll, and to obtain an adhesive layer with further improved followability to the bending of the member and the stepped portion of the surface.

As the polycarbonate polyol, for example, one obtained by reacting a carbonate ester and/or phosgene with a low-molecular-weight polyol described later can be used.

Examples of the carbonic acid ester include methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate, and the like.

Examples of low-molecular-weight polyols capable of reacting with the carbonic acid ester and phosgene include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, triethylene glycol, and triethylene glycol. Propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexane Diol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol , 2-methyl-1,3-propanediol, neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3- Hexanediol, 2-methyl-1,8-octanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcinol, bisphenol A, bisphenol F, 4,4'-biphenol and the like can be used.

As the polycarbonate polyol, it is preferable to use an aliphatic polycarbonate polyol or an alicyclic polycarbonate polyol.

As the aliphatic polycarbonate polyol, an adhesive layer using the curable adhesive composition containing the polyurethane (A′), for example, in order to impart a level of tackiness that allows attachment at room temperature, a dialkyl carbonate, Those obtained by reacting with one or more polyols selected from the group consisting of 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol and 1,6-hexanediol is preferably used.

As the alicyclic polycarbonate polyol, an adhesive sheet having an adhesive layer using the curable adhesive composition containing the polyurethane (A′) is imparted with a level of tackiness that can be applied at room temperature, for example, and In order to impart excellent initial cohesive strength, it is preferable to use, for example, those obtained by reacting a dialkyl carbonate with a polyol containing one or more selected from the group consisting of cyclohexanedimethanol and derivatives thereof.

As the polycarbonate polyol, a urethane resin having a loss tangent (tan δ ₄₀ and tan δ ₆₀ ) within the predetermined range is formed, and excellent handleability before curing. For example, a curable adhesive containing the polyurethane (A′) Even when an adhesive sheet having an adhesive layer using the composition is wound on a roll or the like and stored, the adhesive layer can be further prevented from being pushed out from the end of the roll, and the member can be protected. In order to obtain an adhesive sheet with further improved flexibility and conformability to surface steps, it is preferable to use one having a number average molecular weight in the range of 500 to 5000, more preferably in the range of 800 to 3000. It is preferable to use those having

The polycarbonate polyol is preferably used in the range of 20% by mass to 80% by mass, more preferably in the range of 30% by mass to 70% by mass, relative to the total amount of the polyol (a'1). Use in the range of 40% by mass to 50% by mass maintains a level of stickiness that can be applied under light and room temperature, and an adhesive using a curable adhesive composition containing the polyurethane (A'). Even when an adhesive sheet having a layer is wound on a roll or the like and stored, it is possible to further prevent the adhesive layer from being pushed out from the end of the roll, and it is possible to follow the bending of the member and the uneven part of the surface. It is preferable for obtaining an adhesive sheet with further improved properties.

Examples of the polyester polyol that can be used for the polyol (a′1) include those obtained by esterification reaction of a low-molecular-weight polyol and polycarboxylic acid, and ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone. A polyester obtained by the above method, a copolymerized polyester thereof, or the like can be used.

Examples of the low-molecular-weight polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and 1,3-butane, which generally have a molecular weight of about 50 to 300. Aliphatic alkylene glycols such as diols, cyclohexanedimethanol, and the like can be used.

Examples of the polycarboxylic acids that can be used in the production of the polyester polyol include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid, phenylenediacetic acid, terephthalic acid, isophthalic acid, and orthophthalic acid. Acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, binaphthyldicarboxylic acid, oxydibenzoic acid, carbonyldibenzoic acid, isophthaloyldibenzoic acid, terephthaloyldibenzoic acid and other aromatic dicarboxylic acids, and their anhydrides or esters. can be done.

As the polyester polyol, a urethane resin having a loss tangent (tan δ ₄₀ and tan δ ₆₀ ) within the predetermined range is formed, and excellent handleability before curing. For example, a curable adhesive containing the polyurethane (A′) Even when an adhesive sheet having an adhesive layer using the composition is wound on a roll or the like and stored, the adhesive layer can be further prevented from being pushed out from the end of the roll, and the member can be protected. In order to obtain an adhesive sheet with further improved flexibility and conformability to surface steps, it is preferable to use an aliphatic polyester polyol, more preferably a linear aliphatic polyester polyol. The straight-chain aliphatic polyester polyol refers to a polyester polyol having no alkyl group in the side chain.

Examples of the polyester polyol include those obtained by reacting the aliphatic alkylene glycol with an aliphatic dicarboxylic acid, and an aliphatic polyester polyol obtained by an esterification reaction of 1,6-hexanediol and adipic acid. is preferably used.

As the polyester polyol, a urethane resin having a loss tangent (tan δ ₄₀ and tan δ ₆₀ ) within the predetermined range is formed, and excellent handleability before curing. For example, a curable adhesive containing the polyurethane (A′) Even when an adhesive sheet having an adhesive layer using the composition is wound on a roll or the like and stored, the adhesive layer can be further prevented from being pushed out from the end of the roll, and the member can be protected. In order to obtain an adhesive sheet with further improved flexibility and conformability to surface steps, it is preferable to use one having a number average molecular weight in the range of 1,000 to 5,000.

In particular, when a polyester polyol obtained by reacting an aliphatic diol such as 1,2-ethanediol or 1,4-butanediol with adipic acid is used as the polyester polyol, the range of 1100 to 2900 is used. When using a polyester polyol obtained by reacting 1,6-hexanediol and adipic acid, it has a number average molecular weight in the range of 1100 to 5000. When using a polyester polyol obtained by reacting 1,6-hexanediol and sebacic acid, it is preferable to use one having a number average molecular weight in the range of 1000 to 5000. preferable.

The polyester polyol is preferably used in the range of 10% by mass to 50% by mass with respect to the total amount of the polyol (a'1), and is preferably used in the range of 20% by mass to 40% by mass. When an adhesive sheet having an adhesive layer using a curable adhesive composition containing the polyurethane (A') is wound up on a roll or the like and stored. Even so, it is preferable for obtaining an adhesive sheet that can further prevent the adhesive layer from being extruded from the end of the roll and has further improved conformability to the bending of the member and the stepped portion of the surface.

As the polyol (a'1), it is preferable to use a combination of the polycarbonate polyol and the polyester polyol.

The polycarbonate polyol and the polyester polyol preferably contain a total of 20 parts by mass or more with respect to 100 parts by mass of the polyol (a'1), and those containing 50 parts by mass or more are used. An adhesive sheet that maintains a sticky level at room temperature and has an adhesive layer using a curable adhesive composition containing the polyurethane (A′) is wound around a roll or the like. To obtain an adhesive sheet which can further prevent the adhesive layer from being extruded from the end of the roll even when it is taken and stored, and which has further improved conformability to the bending of the member and the stepped portion of the surface. It is preferable.

When the polycarbonate polyol and the polyester polyol are used in combination, the [polycarbonate polyol/polyester polyol] (mass ratio) is preferably in the range of 0.4 to 7.0, preferably 1.0 to 2.0. The range of 0 forms a urethane resin having a loss tangent (tan δ ₄₀ and tan δ ₆₀ ) within the predetermined range, and as a result, maintains a level of adhesiveness that can be applied at room temperature. Even when an adhesive sheet having an adhesive layer using a curable adhesive composition containing polyurethane (A') is wound on a roll or the like and stored, the adhesive layer is extruded from the end of the roll. It is more preferable for obtaining an adhesive sheet which can further prevent the deformation and which has further improved conformability to the bending of the member and the stepped portion of the surface.

A polyether polyol can also be used as the polyol (a'1). As the polyether polyol, for example, one obtained by addition polymerization of alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator can be used.

Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, bisphenol A, glycerin, tri Methylolethane, trimethylolpropane, and the like can be used.

Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin and tetrahydrofuran.

As the polyether polyol, it is preferable to use an aliphatic polyether polyol or a polyether polyol having an alicyclic structure.

Examples of the polyether polyol include polytetramethylene glycol obtained by ring-opening polymerization of tetrahydrofuran, polytetramethylene glycol derivatives obtained by reacting tetrahydrofuran with alkyl-substituted tetrahydrofuran, and copolymerization of neopentyl glycol and tetrahydrofuran. A polytetramethylene glycol derivative or the like can be used. Among them, the polyether polyol is used to maintain the level of sticking property that the adhesive sheet including the adhesive layer can have at room temperature, and to provide excellent flexibility, durability (especially hydrolysis resistance), and the like. For improvement, it is preferable to use polytetramethylene glycol (PTMG) and polytetramethylene glycol derivative (PTXG).

In addition, the polyol (a'1) suppresses displacement and deformation of the adhesive layer over time after bonding of the cured product (adhesive layer after curing) formed by curing the adhesive sheet. For that purpose, it is preferable to use an aromatic polyol. By using the aromatic polyol, the rigidity of the polyurethane (A') can be improved.

Examples of the aromatic polyols include hydroquinone, resorcinol, dihydroxyphenyl, naphthalene diol, dihydroxydiphenyl ether, bisphenol F, bisphenol A, adducts obtained by adding alkylene oxides such as ethylene oxide and propylene oxide to bisphenol A (diethoxylated bisphenol A etc.), p-xylylene glycol, m-xylylene glycol, o-xylylene glycol, 4,4′-bishydroxymethylbiphenyl, 4,2′-bishydroxymethylbiphenyl, 2,2′-bishydroxymethyl Biphenyl, 4,3'-bishydroxymethylbiphenyl, 3,3'-bishydroxymethylbiphenyl, 3,2'-bishydroxymethylbiphenyl, phenol novolak, cresol novolak, 1,4-benzenedimethanol, 1,3- benzenedimethanol, 1,2-benzenedimethanol, 4,4'-naphthalenedimethanol, 3,4'-naphthalenedimethanol, modified compounds thereof, and the like.

As the polyol (a'1), other polyols can be used in addition to those mentioned above. Examples of the other polyols include acrylic polyols.

As the polyol (a'1), it is preferable to use one having a number average molecular weight in the range of 500 to 5000, and it is preferable to use one having a number average molecular weight in the range of 1000 to 3000. , coating workability, initial cohesive strength, and the like to obtain an adhesive layer. In addition, the said number average molecular weight is the value measured on the following conditions.

[Method for measuring number average molecular weight]
The measurement of the number average molecular weight described in the present invention is a value measured under the following conditions by gel permeation chromatography (GPC) in terms of polystyrene.

Resin sample solution; 0.4 mass% tetrahydrofuran (THF) solution Measurement device model number; HLC-8220GPC (manufactured by Tosoh Corporation)
Column; TSKgel (manufactured by Tosoh Corporation)
Eluent; tetrahydrofuran (THF)

Alicyclic polyisocyanate, aliphatic polyisocyanate, aromatic polyisocyanate and the like can be used as the polyisocyanate (a'2) that can be used in the production of the polyurethane (A').

In addition, it is preferable to use an alicyclic polyisocyanate as the polyisocyanate (a'2) in order to obtain an adhesive sheet with further improved conformability to the bending of the member and the stepped portion of the surface.

Examples of the alicyclic polyisocyanate include isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 4,4′-dicyclohexylmethane diisocyanate, 2,4- and/or 2,6-methylcyclohexane diisocyanate, cyclohexane Cylylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate and 2,5- and/or 2,6-norbornane diisocyanate, dimer acid diisocyanate, bicycloheptane Triisocyanate and the like can be used alone or in combination of two or more.

As the alicyclic polyisocyanate, among those mentioned above, in order to obtain an adhesive sheet having good reactivity with the polyol (a'1) and having excellent heat resistance, light transmittance, etc., Preference is given to using 4,4'-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane (BICH).

In addition, as the polyisocyanate (a'2), the use of an aromatic polyisocyanate is advantageous in that the adhesive layer after bonding the cured product (adhesive layer after curing) formed by curing the adhesive sheet. This is preferable for suppressing displacement and deformation over time.

Examples of the aromatic polyisocyanate include diphenylmethane diisocyanates (MDI) such as 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 2,2'-diphenylmethane diisocyanate, polynuclear polyphenylene polymethyl polyisocyanate (polymeric MDI), tolylene diisocyanate (TDI) such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, naphthalene diisocyanate (NDI) such as 1,4-naphthalene diisocyanate and 1,5-naphthalene diisocyanate; 5-tetrahydronaphthalene diisocyanate; phenylene diisocyanate (PDI) such as 1,2-phenylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate (PDI), xylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI); toridine Diisocyanate (TODI), 2,4,6-trimethylphenyl-1,3-diisocyanate, 2,4,6-triisopropylphenyl-1,3-diisocyanate, chlorophenylene-2,4-diisocyanate, 4,4'- diphenyl ether diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-diphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, and These modified compounds and the like are included.

As the aromatic polyisocyanate, among the above-mentioned, it has good reactivity with the polyol (a'1), and a cured product formed by curing the adhesive sheet (adhesive layer after curing ), diphenylmethane diisocyanate (MDI ), tolylene diisocyanate (TDI) such as 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, naphthalene diisocyanate (NDI) such as 1,4-naphthalene diisocyanate and 1,5-naphthalene diisocyanate is preferred.

As a method for producing a polyurethane (A') having an isocyanate group by reacting the polyol (a'1) with the polyisocyanate (a'2), for example, the polyol (a'1) charged in a reaction vessel is , after removing moisture by heating under normal pressure or reduced pressure conditions, the polyisocyanate (a'2) is supplied all at once or dividedly to react.

The reaction between the polyol (a'1) and the polyisocyanate (a'2) is the equivalent ratio of the isocyanate groups of the polyisocyanate (a'2) to the hydroxyl groups of the polyol (a'1) ( Hereinafter referred to as [NCO/OH equivalent ratio]) is preferably in the range of 1.1 to 20.0, more preferably in the range of 1.1 to 13.0, and more preferably in the range of 1.1 to 5.0. A range of 0 is more preferable, and a range of 1.5 to 3.0 is particularly preferable.

The reaction conditions (temperature, time, etc.) between the polyol (a'1) and the polyisocyanate (a'2) may be appropriately set in consideration of various conditions such as safety, quality, and cost, and are not particularly limited. For example, the reaction temperature is preferably in the range of 70 to 120° C., and the reaction time is preferably in the range of 30 minutes to 5 hours.
When the polyol (a'1) and the polyisocyanate (a'2) are reacted, a catalyst such as a tertiary amine catalyst or an organometallic catalyst can be used as necessary. .
Moreover, the reaction may be carried out in a solventless environment or in the presence of an organic solvent.

Examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, methyl butyl ketone, and cyclohexanone; and ether esters such as methyl cellosolve acetate and butyl cellosolve acetate. A solvent, an aromatic hydrocarbon solvent such as toluene and xylene, an amide solvent such as dimethylformamide and dimethylacetamide, and the like can be used alone or in combination of two or more. The organic solvent may be removed by an appropriate method such as heating under reduced pressure or drying under normal pressure during the production of the polyurethane (A') or after the production of the polyurethane (A').

As the curable adhesive composition containing the polyurethane (A), one containing a polymerizable compound (B) can be used.
As the polymerizable compound (B), it is preferable to use a compound that undergoes a polymerization reaction with the polyurethane (A) to form a cured product.
The polymerizable compound (B) preferably has a polymerizable functional group other than a polymerizable unsaturated double bond. By having a polymerizable functional group other than a polymerizable unsaturated double bond, polymerization can proceed not only by irradiation of light but also by a dark reaction. Is possible.
As the polymerizable compound (B), it is preferable to contain a thermally polymerizable compound and a photopolymerizable compound, and it is more preferable to use a photopolymerizable compound because the polymerization reaction can proceed at a low temperature. .

Examples of the photopolymerizable compound include photoradical polymerizable compounds, photocationically polymerizable compounds, and photoanionically polymerizable compounds. It is not inhibited by oxygen, the reaction continues to progress even after light irradiation, and by laminating the bonding material after irradiating it with light, it is possible to laminate even on a member that does not transmit light. preferred because it is possible. Furthermore, it is more preferable to use a cationic polymerizable compound because it is excellent in reactivity after light irradiation and easily obtains high bondability after curing. The photopolymerizable compounds may be used alone or in combination.

The photo-cationically polymerizable compound is not particularly limited as long as it has one or more photo-cationically polymerizable functional groups in one molecule. The photocationically polymerizable compound has one or more photocationically polymerizable functional groups such as epoxy group, oxetanyl group, hydroxyl group, vinyl ether group, episulfide group, ethyleneimine group and oxazoline group in one molecule. is preferred. Among them, a photo cationic polymerizable compound having an epoxy group or an oxetanyl group is more preferable in order to obtain high curability and bondability after curing.

As the cationic photopolymerizable compound having an epoxy group, 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-oxa-10-phosphaphenanthrene-10-oxide modified epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, hexanediol type epoxy resin, triphenylmethane type epoxy resin, tetra Phenylethane type epoxy resin, dicyclopentadiene-phenol addition reaction type epoxy resin, phenol aralkyl type epoxy resin, naphthol novolak type epoxy resin, naphthol aralkyl type epoxy resin, naphthol-phenol co-condensation novolac type epoxy resin, naphthol-cresol co-condensation Novolak type epoxy resin, aromatic hydrocarbon formaldehyde resin-modified phenol resin type epoxy resin, biphenyl-modified novolak type epoxy resin, trimethylolpropane type epoxy resin, alicyclic epoxy resin, acrylic resin having epoxy group, polyurethane having epoxy group A resin, a polyester resin having an epoxy group, a flexible epoxy resin, or the like can be used.
Among them, as the epoxy resin, by using an alicyclic epoxy resin or a polyfunctional aliphatic epoxy resin, it is possible to obtain a bonding material having excellent curability due to the excellent cationic photopolymerizability. preferable. Since these materials are excellent in the cationic photopolymerizability, a bonding material having excellent curability can be obtained, and a suitable elastic modulus for suppressing deformation over time of the adhesive layer after bonding can be imparted. can be done.

Furthermore, other resin components may be blended or added to these to increase flexibility, or to improve adhesive strength and bending strength. Carboxyl group-containing butadiene-acrylonitrile rubber) modified epoxy resin; epoxy resin in which various rubbers such as acrylic rubber, NBR, SBR, butyl rubber, or isoprene rubber are dispersed; epoxy resin modified with liquid rubber as described above; , urethane, urea, polyester, and styrene; chelate-modified epoxy resins; and polyol-modified epoxy resins.

Examples of the cationic photopolymerizable compound having an oxetanyl group include 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 1,4-bis[(3-methyl-3-oxetanylmethoxy)methyl ] Benzene, 3-methyl-3-glycidyloxetane, 3-ethyl-3-glycidyloxetane, 3-methyl-3-hydroxymethyloxetane, 3-ethyl-3-hydroxymethyloxetane, di{1-ethyl (3-oxetanyl )} and oxetane compounds such as methyl ether.

The polymerizable compound (B) is preferably used in the range of 10% by mass to 70% by mass, more preferably in the range of 20% by mass to 40% by mass with respect to the total amount of the curable adhesive composition. Even when the adhesive sheet is wound on a roll or the like and stored, the adhesive layer can be further prevented from being extruded from the end of the roll without deteriorating the bondability after curing. This is more preferable in that it is possible to obtain an adhesive sheet with further improved flexibility and conformability to stepped portions on the surface.

As the curable adhesive composition containing the polyurethane (A) of the present invention, those containing other components as necessary in addition to the polymerizable compound (B) can be used.
The curable adhesive composition containing the polyurethane (A) of the present invention contains a polymerization initiator in order to promote reactivity after applying an external stimulus and to obtain high bondability after curing. It is preferred to use
The polymerization initiator may be one that is activated by an external stimulus. For example, in the case of using a cationically polymerizable compound as the polymerizable compound, one that activates a cationically polymerizable functional group is used. It is preferred to use

Moreover, as the polymerization initiator, there are, for example, a photopolymerization initiator and a thermal polymerization initiator, which may be used alone or in combination of the two. Among them, it is preferable to use a photopolymerization initiator whose reaction proceeds with light as an external stimulus in order to obtain a reaction at a low temperature and a good curing reaction. As a result, it is possible to obtain high bondability without damaging the laminated members, deforming the members due to strain between the members, or causing cracks between the bonding material and the members.
As the light, appropriate light such as ultraviolet light and visible light can be used, but it is preferable to use light with a wavelength of 300 nm or more and 420 nm or less.

The photopolymerization initiator may be one that is activated by light, and includes, for example, a photoradical polymerization initiator, a photocationic polymerization initiator, and a photoanion polymerization initiator. It is preferable to use an anionic polymerization initiator, and it is preferable to use a photocationic polymerization initiator because polymerization by a dark reaction can be suitably adjusted.

The photocationic polymerization initiator is not particularly limited as long as it can induce a ring-opening reaction of the cationic polymerizable functional group by light of the wavelength used, but cationic polymerization is performed by light of a wavelength of 300 to 370 nm. A compound that induces a ring-opening reaction of the functional group of the polar group and is inactive in a wavelength region exceeding 370 nm is preferably used. Such compounds include, for example, aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium onium salts such as salts.

Specific examples of such onium salts include Optomer SP-150, Optomer SP-170, Optomer SP-171 (all manufactured by ADEKA), UVE-1014 (manufactured by General Electronics), OMNICAT250 and OMNICAT270 (all Also manufactured by IGM Resin), IRGACURE290 (manufactured by BASF), San-Aid SI-60L, San-Aid SI-80L, San-Aid SI-100L (both manufactured by Sanshin Chemical Co., Ltd.), CPI-100P, CPI-101A, CPI-200K (both of which are manufactured by San-Apro Co., Ltd.).

In addition, the said photocationic polymerization initiator may be used individually, and 2 or more types may be used together. Furthermore, two-stage curing may be performed using a plurality of photocationic polymerization initiators having different effective active wavelengths.
The photocationic polymerization initiator may be used in combination with an anthracene-based, thioxanthone-based sensitizer, or the like, if necessary.
The mixing ratio of the photocationic polymerization initiator is preferably in the range of 0.001 parts by mass to 30 parts by mass with respect to 100 parts by mass of the curable adhesive composition containing the polyurethane (A). It is preferably used in the range of 0.01 to 20 parts by mass, more preferably in the range of 0.1 to 10 parts by mass. If the blending ratio of the photocationic polymerization initiator is too small, the curing required to develop high bondability will be insufficient. It becomes difficult to join members that cannot transmit through each other.

As the adhesive layer using the curable adhesive composition containing the polyurethane (A), the adhesive sheet is wound up on a roll or the like, and even when the roll is stored, the adhesive layer does not extend from the end of the roll. In order to obtain an adhesive sheet that can be further prevented from being extruded and has further improved conformability to the bending of members and stepped portions on the surface, an adhesive resin having a weight average molecular weight in the range of 2,000 to 2,000,000 can be used. . A preferred weight average molecular weight range is 5,000 to 1,000,000, and a more preferred weight average molecular weight range is 5,000 to 800,000.

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

As the adhesive resin, it is preferable that the adhesive resin has adhesiveness at room temperature, because the sticking property is improved when the bonding material is laminated on the member. In order to impart tackiness to the adhesive resin, the glass transition temperature of the adhesive resin is preferably in the range of -30 to 20°C, more preferably in the range of -25 to 10°C. . When the glass transition temperature is within the above range, the pressure-sensitive adhesive layer can be provided with adhesiveness and a high elastic modulus, and the bonding strength of the bonding material can be improved.

The glass transition temperature of the adhesive resin is measured using, for example, a dynamic viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD). is sandwiched, the storage elastic modulus (G′) and the loss elastic modulus (G″) at a frequency of 1.0 Hz are measured, and the value obtained by dividing the loss elastic modulus (G″) by the storage elastic modulus (G′) ( It can be calculated as the temperature at which the loss tangent (tan δ) that can be calculated by G″/G′) becomes the maximum value.

Since the adhesive resin may be crosslinked, a functional group capable of reacting with the functional group contained in the crosslinking agent or the polymerizable compound may be introduced. Examples of the functional group include a hydroxyl group, a carboxyl group, an epoxy group, an amino group, and the like, and it is preferable to appropriately select the functional group within a range that does not hinder the polymerization of the polymerizable compound described above.

The adhesive resin is preferably used in the range of 1 part by mass to 900 parts by mass with respect to 100 parts by mass of the curable adhesive composition containing the polyurethane (A), and in the range of 5 to 500 parts by mass. It is preferably used, more preferably in the range of 10 parts by mass to 300 parts by mass. By adjusting the content of the adhesive resin within the above range, the adhesive layer does not deteriorate even when the adhesive sheet is wound up on a roll or the like and stored, without deteriorating the bondability after curing. It is possible to obtain an adhesive sheet which can be further prevented from being extruded from the end of the adhesive sheet, and which has further improved followability to the bending of the member and the stepped portion of the surface.

As the adhesive layer, one containing other additives can be used as necessary.
Examples of the additives include fillers such as aluminum hydroxide, aluminum oxide, aluminum nitride, magnesium hydroxide, magnesium oxide, mica, talc, boron nitride, and glass flakes, silane coupling agents, phosphoric acid additives, and acrylate additives. agents, tackifiers and the like can be used. In particular, it is preferable to use a silane coupling agent that is highly reactive with glass, since an adhesive sheet having excellent adhesion to members made of glass or the like can be obtained. It is more preferred to use a type silane coupling agent.
In addition to the additives described above, other additives, such as softeners, stabilizers, adhesion promoters, leveling agents, antifoaming agents, plasticizers, tackifying resins, fibers , antioxidants, hydrolysis inhibitors, thickeners, colorants such as pigments, and additives such as fillers.

An adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention may have the adhesive layer on both sides of a sheet-like substrate, or may not have the sheet-like substrate. A so-called substrate-less adhesive sheet composed of the adhesive layer may also be used. As the adhesive sheet, a sheet composed of a single adhesive layer may be used, or a laminate of two or more same or different adhesive layers may be used.
Further, an adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention can be obtained, for example, by applying the adhesive composition to the surface of a release sheet and drying it as necessary to remove the adhesive layer. It can be manufactured by forming and removing the release sheet.

An adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention can be produced, for example, by applying the adhesive composition to both sides of a sheet-like substrate and drying as necessary to form an adhesive layer. can be manufactured by Further, the adhesive sheet of the present invention is formed by, for example, applying the adhesive composition to the surface of a release sheet, drying it as necessary to form an adhesive layer, and applying a sheet-like substrate on the surface of the adhesive layer. can be manufactured by affixing

When manufacturing an adhesive sheet in which two or more adhesive layers having the same or different compositions are laminated, for example, the adhesive composition 1 is applied to both sides of a sheet-like substrate, and dried as necessary. to form an adhesive layer 1, apply another adhesive composition 2 on the surface of the adhesive layer 1, and dry as necessary to form an adhesive layer 2.

In addition, the adhesive sheet forms the adhesive layer 1 by applying the adhesive composition 1 on the surface of the release sheet, drying if necessary, and another adhesive layer on the surface of the adhesive layer 1. It can be produced by applying the agent composition 2 and drying it as necessary to form the adhesive layer 2 .

In the production of an adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention, in order to improve the work efficiency in forming the composition containing the polymerizable compound and the like into the sheet and the like. In addition to the polymerizable compound and the polymerization initiator, it is preferable to use one containing a solvent.
Examples of the solvent include ester solvents such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone solvents such as acetone, methyl ketyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone; aromatic solvents such as toluene and xylene. A hydrocarbon solvent or the like can be used.

An adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention can be produced by mixing the polymerizable compound with optional components such as the polymerization initiator and solvent. When the above-described components are mixed to produce the bonding material (X), a dissolver, butterfly mixer, BDM twin shaft mixer, planetary mixer, etc. can be used as necessary. is preferred, and when the conductive fillers are used, it is preferred to use a planetary mixer to improve their dispersibility.

The polymerization initiator is preferably used before curing the adhesive sheet or before molding the adhesive sheet into a sheet or the like.
Alternatively, the adhesive sheet can be obtained, for example, by producing a composition containing the polymerizable compound and optional components such as the polymerization initiator and solvent, then coating the surface of the release liner, and drying the composition. can be manufactured.
The drying is preferably performed at a temperature of about 40° C. to 120° C., more preferably about 50° C. to 90° C., in order to suppress the progress of the curing reaction of the sheet-like bonding material. Moreover, it is preferable because foaming on the sheet surface due to rapid volatilization of the solvent or the like can be suppressed.

The adhesive sheet may be sandwiched between the release liners before use.
Examples of the release liner include paper such as kraft paper, glassine paper, and fine paper; resin films such as polyethylene, polypropylene (OPP, CPP), and polyethylene terephthalate; laminated paper obtained by laminating the paper and resin film; It is possible to use a material that has been subjected to filling treatment with clay, polyvinyl alcohol, or the like, and that has been subjected to release treatment with silicone resin or the like on one or both sides thereof.

The thickness of the adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention obtained by the above method is not particularly limited, but a thickness of 10 μm to 2000 μm is used. A thickness of 25 μm to 1500 μm is preferred, and a thickness of 50 μm to 1000 μm is preferred. The adhesive sheet having the above thickness can further prevent the adhesive layer from being extruded from the end of the roll even when the adhesive sheet is wound on a roll or the like and stored, thereby preventing bending of the member and deformation of the surface. This is preferable because the followability to the stepped portion can be adjusted appropriately.

The temperature at which the adhesive sheet is stored is preferably −10° C. or higher, more preferably 5° C. or higher, and 23° C. or higher to reduce water absorption of the adhesive sheet due to dew condensation. It is more preferable because it can suppress the decrease in curability of the adhesive sheet.

When the adhesive sheet is applied with an external stimulus, polymerization is initiated and curing progresses. Examples of external stimuli include light, heat, water (humidity), etc. The use of light cures the adhesive sheet at a low temperature, and the storage stability before curing can be made suitable. preferable.

Ultraviolet rays are preferably used as the light used when the adhesive sheet is cured and the members are adhered. The ultraviolet rays may be irradiated in an atmosphere of an inert gas such as nitrogen gas, or may be irradiated in an air atmosphere, in order to efficiently perform the curing reaction using the ultraviolet rays. In addition, if necessary, heat may be used together as an energy source, and heating may be performed after irradiating with light.

When using ultraviolet rays as light, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, electrodeless lamps (fusion lamps), chemical lamps, black light lamps, mercury-xenon lamps, short arc lamps, helium - Cadmium laser, argon laser, sunlight, LED, and the like. Also, a xenon-flash lamp capable of emitting light in a flashing manner is preferable because the influence of heat on the substrate can be minimized.
As the light irradiation device, in addition to the devices described above, a germicidal lamp, a carbon arc, a xenon lamp, a metal halide lamp, a scanning type, a curtain type electron beam accelerator, or the like can be used.

The cured product (adhesive layer after curing) formed by curing the adhesive sheet has a storage elastic modulus (E′ ₂₅ ) at 25° C. of 1.0×10 ⁵ Pa when measured at a frequency of 1.0 Hz. 1.0×10 ⁶ Pa or more, preferably 1.0×10 ⁷ Pa or more. By setting the thickness within the above range, it is possible to suppress displacement and deformation of the adhesive layer after bonding over time.

The cured product (adhesive layer after curing) formed by curing the adhesive sheet has a storage elastic modulus (E′ ₄₀ ) at 40° C. of 1.0×10 ⁴ Pa when measured at a frequency of 1.0 Hz. In addition, it is preferable that the storage elastic modulus (E′ ₆₀ ) at 60° C. is 1.0×10 ⁴ Pa or more when measured at a frequency of 1.0 Hz. By setting the content within the above range, it is possible to obtain a level of adhesiveness that does not cause peeling over time.

The dynamic viscoelasticity of the cured product (adhesive layer after curing) formed by curing the adhesive sheet was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometrics, trade name: RSA-II). is the value In the measurement, a cured product (adhesive layer after curing) having a thickness of 100 μm formed by curing the adhesive sheet was prepared, and a dumbbell cutter was used to cut it into a test piece type 5 shape of JIS K 7127. I used the one that was punched out.

As a method for laminating an adhesive sheet having an adhesive layer using the curable adhesive composition of the present invention to a member, for example, the step [1] of applying an external stimulus to the adhesive sheet; The manufacturing method preferably includes the step [2] of attaching to (C1) and the step [3] of curing the adhesive sheet in this order.
Further, the step [0] of attaching the adhesive sheet to the other member (C2) is included before the step [1] or between the step [1] and the step [2].

In addition, when the member (C1) and/or the member (C2) has flexures and/or irregularities, it is preferable to apply the adhesive sheet to fill the flexures and/or irregularities.
It is preferable that the step of filling the flexure and/or the unevenness is performed before the step [3], because the followability to the flexure and the unevenness is excellent and the members can be sufficiently bonded after curing.

The step of filling the deflection and/or unevenness is performed while heating as long as the members to be laminated are not damaged, the members are deformed due to strain between the members, and cracks are not generated between the bonding material and the members. May be pasted. By including the heating step, when the members are joined via the adhesive sheet, they can be brought into closer contact with each other and a high joint strength can be obtained.

The upper limit temperature for heating is preferably 150° C. or less, more preferably 120° C. or less, still more preferably 100° C. or less, and 80° C. or less suppresses damage to members and deformation of members due to strain occurring between members. Also, it is most preferable to prevent cracks from occurring between the bonding material and the member. Moreover, it is preferable that the lower limit temperature for heating is 40° C. or more, because the adhesive sheet is excellent in followability to bending and unevenness.

In the step [3], it is hardened while heating to the extent that the members to be laminated are not damaged, the members are not deformed due to strain between the members, and cracks are not generated between the bonding material and the members. good too. By including the heating step, high bonding strength can be obtained in a shorter time when the members are bonded via the adhesive sheet.

In the step [3], the heating temperature is preferably 150° C. or less, more preferably 120° C. or less, still more preferably 100° C. or less, and 80° C. or less damages the laminated members and deforms and flows the bonding material. It is most preferable to suppress

The step [2] is preferably performed within 24 hours, more preferably within 12 hours, even more preferably within 3 hours, and within 1 hour after performing the step [1]. This is the most preferable because when the adhesive sheet is adhered to a member, it can be adhered more firmly and a high bonding strength can be obtained.

The step [3] may include a heating step as long as it does not damage the laminated members, deform the members due to strain between the members, or cause cracks between the bonding material and the members. good. By including the heating step, after the bonding material (X) and the adherend (C1) are laminated, the time required for curing the bonding material (X) is shortened, and the production method of the present invention is performed. It can be completed in a short time.

In the step [3], the heating temperature is preferably 150° C. or less, more preferably 120° C. or less, still more preferably 100° C. or less, and 80° C. or less suppresses damage to the members and causes strain between the members. It is most preferable to prevent the deformation of the member and cracks occurring between the bonding material and the member.

The laminate is relatively flexible before curing, so it has excellent followability to members that are bent or uneven, and after curing, it can sufficiently bond members, so it is mainly used for image display devices. It can be used as a bonding material between various members.

Examples of the image display device include personal computers, mobile phones, smartphones, mobile terminals (PDA) such as tablet PCs, game machines, televisions (TV), car navigation systems, touch panels, pen tablets, LCDs, PDPs or ELs, organic ELs, Constituent members of a flat image display device using an image display panel equipped with micro LEDs, quantum dots (QD), and the like can be mentioned. Examples of constituent members include an image display panel, a circuit board, a rear cover, a bezel, a frame, and a chassis. Since the adhesive sheet of the present invention can firmly bond members together after curing, it can also be used for bonding members constituting large-sized image display devices used for industrial and advertising purposes.

EXAMPLES The present invention will be described in more detail with reference to examples and comparative examples below.

<Preparation of Polyurethane (X-1)>
In a reaction vessel, 50 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,6-hexanediol and adipic acid were added. 30 parts by mass of a polyester polyol having a number average molecular weight of 4,500 obtained by the reaction was mixed and dehydrated by heating to 100° C. under reduced pressure until the moisture content reached 0.05% by mass.

Next, after mixing the mixture of the aliphatic polycarbonate polyol and the polyester polyol cooled to 70° C. with 14.5 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature was raised to 100° C., A polyurethane (X-1) was obtained by reacting for 3 hours. The polyurethane (X-1) has an isocyanate group as a polymerizable functional group.

<Preparation of Polyurethane (X-2)>
In a reaction vessel, 40 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,6-hexanediol and adipic acid were added. 40 parts by mass of a polyester polyol having a number average molecular weight of 4,500 obtained by the reaction was mixed and heated to 100° C. under reduced pressure to dehydrate until the moisture content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 13.7 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature is raised to 100° C., A polyurethane (X-2) was obtained by reacting for 3 hours. The polyurethane (X-2) has an isocyanate group as a polymerizable functional group.

<Preparation of Polyurethane (X-3)>
In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,6-hexanediol and adipic acid were added. 20 parts by mass of a polyester polyol having a number average molecular weight of 4500 obtained by the reaction was mixed and dehydrated by heating to 100° C. under reduced pressure until the moisture content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 16.3 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature is raised to 100° C., A polyurethane (X-3) was obtained by reacting for 3 hours. The polyurethane (X-3) has an isocyanate group as a polymerizable functional group.

<Preparation of Polyurethane (X-4)>
In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,6-hexanediol and adipic acid were added. 20 parts by mass of a polyester polyol having a number average molecular weight of 4500 obtained by the reaction was mixed and dehydrated by heating to 100° C. under reduced pressure until the moisture content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 15.3 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature is raised to 100° C., A polyurethane (X-4) was obtained by reacting for 3 hours. The polyurethane (X-4) has an isocyanate group as a polymerizable functional group.

<Preparation of Polyurethane (X-5)>
In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,6-hexanediol and adipic acid were added. 20 parts by mass of a polyester polyol having a number average molecular weight of 4500 obtained by the reaction was mixed and dehydrated by heating to 100° C. under reduced pressure until the moisture content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 4.5 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature is raised to 100° C., Polyurethane (X-5) was obtained by reacting for 3 hours until the hydroxyl group content became constant. The polyurethane (X-5) has a hydroxyl group as a polymerizable functional group.

<Preparation of Polyurethane (X-6)>
In a reaction vessel, 14 parts by mass of an aromatic polyester polyol having a number average molecular weight of 2000 obtained by reacting 6 mol of ethylene oxide adduct of bisphenol A, isophthalic acid and sebacic acid, 2 mol of ethylene oxide adduct of bisphenol A, phthal 37 parts by mass of an aromatic polyester polyol having a number average molecular weight of 1300 obtained by reacting an acid and adipic acid, and an aliphatic polyester polyol 32 having a number average molecular weight of 3500 obtained by reacting 1,6-hexanediol and dodecanedioic acid. Parts by mass, 7 parts by mass of polypropylene glycol having a number average molecular weight of 1,000, and 2 parts by mass of an adduct of 2 mol of ethylene oxide of bisphenol A were mixed and heated to 100°C under reduced pressure conditions to reduce the water content to 0.00. dehydrated to 05% by weight.

Next, after cooling the mixture to 70° C. and mixing 8.0 parts by mass of 4,4′-diphenylmethane diisocyanate, the temperature was raised to 100° C. and reaction was performed for 3 hours until the hydroxyl group content became constant. Polyurethane (X-6) was obtained. The polyurethane (X-6) has a hydroxyl group as a polymerizable functional group.

<Preparation of Polyurethane (X-7)>
In a reaction vessel, 14 parts by mass of an aromatic polyester polyol having a number average molecular weight of 2000 obtained by reacting 6 mol of ethylene oxide adduct of bisphenol A, isophthalic acid and sebacic acid, 2 mol of ethylene oxide adduct of bisphenol A, phthal 37 parts by mass of an aromatic polyester polyol having a number average molecular weight of 1300 obtained by reacting an acid and adipic acid, and an aliphatic polyester polyol 32 having a number average molecular weight of 3500 obtained by reacting 1,6-hexanediol and dodecanedioic acid. Parts by mass, 7 parts by mass of polypropylene glycol having a number average molecular weight of 1,000, and 2 parts by mass of an adduct of 2 mol of ethylene oxide of bisphenol A were mixed and heated to 100°C under reduced pressure conditions to reduce the water content to 0.00. dehydrated to 05 mass %.

Next, after cooling the mixture to 70° C. and mixing 8.4 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature was raised to 100° C., and the content of hydroxyl groups became constant. Polyurethane (X-7) was obtained by reacting for time. The polyurethane (X-7) has a hydroxyl group as a polymerizable functional group.

<Preparation of Polyurethane (X'-1)>
In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,4-butanediol and adipic acid were added. 20 parts by mass of a polyester polyol having a number average molecular weight of 1000 obtained by the reaction was mixed and dehydrated by heating to 100° C. under reduced pressure until the water content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 20 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature was raised to 100° C. for 3 hours. A urethane prepolymer having an isocyanate group was obtained by the reaction.

100 parts by mass of the urethane prepolymer melted by heating at 100° C., 11.4 parts by mass of 2-hydroxyethyl acrylate and 0.01 part by mass of stannous octoate were mixed, and the NCO% at 100° C. was mixed. Polyurethane (X'-1) was obtained by reacting until constant. Polyurethane (X'-1) has a polymerizable unsaturated double bond as a polymerizable functional group.

The isocyanate group content (NCO%) of the polyurethane (X'-1) having a polymerizable unsaturated double bond obtained by the above method was 0% by mass.

<Preparation of Polyurethane (X'-2)>
In a reaction vessel, 40 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,6-hexanediol and adipic acid were added. 40 parts by mass of a polyester polyol having a number average molecular weight of 4,500 obtained by the reaction was mixed and heated to 100° C. under reduced pressure to dehydrate until the moisture content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 13.7 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature is raised to 100° C., A urethane prepolymer having an isocyanate group was obtained by reacting for 3 hours.

100 parts by mass of the urethane prepolymer melted by heating at 100° C., 1.6 parts by mass of 2-hydroxyethyl acrylate and 0.01 part by mass of stannous octoate were mixed, and the NCO% at 100° C. was mixed. Polyurethane (X'-2) was obtained by reacting until constant. Polyurethane (X'-2) has a polymerizable unsaturated double bond as a polymerizable functional group.

The isocyanate group content (NCO%) of the polyurethane (X'-2) having a polymerizable unsaturated double bond obtained by the above method was 0% by mass.

<Preparation of Polyurethane (X'-3)>
In a reaction vessel, 60 parts by mass of an aliphatic polycarbonate polyol having a number average molecular weight of 2000 obtained by reacting 1,5-pentanediol, 1,6-hexanediol and dialkyl carbonate, 1,4-butanediol and adipic acid were added. 20 parts by mass of a polyester polyol having a number average molecular weight of 1000 obtained by the reaction was mixed and dehydrated by heating to 100° C. under reduced pressure until the water content reached 0.05% by mass.

Next, after cooling the mixture of the aliphatic polycarbonate polyol and the polyester polyol to 70° C. and mixing 20 parts by mass of dicyclohexylmethane-4,4′-diisocyanate, the temperature was raised to 100° C., and isocyanate group Polyurethane (X'-3) was obtained by reacting for 3 hours until the content became constant. Polyurethane (X'-3) has an isocyanate group as a polymerizable functional group.

<Preparation of acrylic (Y'-1)>
75 parts by mass of methoxyethyl acrylate, 24 parts by mass of n-butyl acrylate, 1 part by mass of 2-hydroxyethyl acrylate and a polymerization initiator were placed in a reaction vessel equipped with a stirrer, a cold current cooler, a thermometer, a dropping funnel and a nitrogen gas inlet. 0.4 parts of 2,2'-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after purging with nitrogen, polymerization is performed at 80 ° C. for 8 hours to obtain an acrylic copolymer having a weight average molecular weight of 350,000, Acrylic (Y'-1) having a non-volatile content of 30% by mass was obtained by mixing the acrylic copolymer and ethyl acetate.

(Example 1)
Polyurethane (X-1) 100 parts by mass, CEL-2021P (manufactured by Daicel Corporation, alicyclic epoxy resin) 43 parts by mass, CPI-100P (manufactured by San-Apro Co., Ltd., sulfonium salt type, solid content concentration 50%) 11.4 The mass parts were mixed and stirred, and methyl ethyl ketone was added to adjust the non-volatile content to 75 mass % to obtain an adhesive composition (a-1).

Next, the adhesive composition (a-1) was applied to the surface of a release liner (one side of a polyethylene terephthalate film having a thickness of 50 μm treated with a silicone compound) using a rod-shaped metal applicator. was applied so that the thickness after drying would be 100 μm.

Furthermore, the coated product was placed in a dryer at 85 ° C. for 5 minutes to dry, and a release liner (one side of a polyethylene terephthalate film having a thickness of 38 μm was treated with a silicone compound for release treatment on one side of the dried coated product. ) were laminated to obtain an adhesive sheet (X-1) having a thickness of 100 μm.

(Example 2)
An adhesive sheet (X-2) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the polyurethane (X-2) was used instead of the polyurethane (X-1).

(Example 3)
An adhesive sheet (X-3) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the polyurethane (X-3) was used instead of the polyurethane (X-1).

(Example 4)
An adhesive sheet (X-4) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the polyurethane (X-4) was used instead of the polyurethane (X-1).

(Example 5)
Example 1 except that the polyurethane (X-5) was used instead of the polyurethane (X-1), and the amount of CPI-100P used was changed from 11.4 parts by mass to 5.7 parts by mass. An adhesive sheet (X-5) having a thickness of 100 μm was obtained in the same manner as above.

(Example 6)
Example 1 except that the polyurethane (X-6) was used instead of the polyurethane (X-1), and the amount of CPI-100P used was changed from 11.4 parts by mass to 2.6 parts by mass. An adhesive sheet (X-6) having a thickness of 100 μm was obtained in the same manner as above.

(Example 7)
Example 1 except that the polyurethane (X-7) was used instead of the polyurethane (X-1), and the amount of CPI-100P used was changed from 11.4 parts by mass to 10.0 parts by mass. An adhesive sheet (X-7) having a thickness of 100 μm was obtained in the same manner as above.

(Example 8)
Instead of the polyurethane (X-1), the polyurethane (X-8) was used, the amount of CEL-2021P used was changed from 43 parts by mass to 38 parts by mass, and N-680 (manufactured by DIC, cresol novolak type epoxy resin) was used, and the amount of CPI-100P used was changed from 11.4 parts by mass to 7.0 parts by mass. (X-8) was obtained.

(Comparative example 1)
An adhesive sheet (X'-1) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the polyurethane (X'-1) was used instead of the polyurethane (X-1).

(Comparative example 2)
An adhesive sheet (X'-2) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the polyurethane (X'-2) was used instead of the polyurethane (X-1).

(Comparative Example 3)
An adhesive sheet (X'-3) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the polyurethane (X'-3) was used instead of the polyurethane (X-1).

(Comparative Example 4)
An adhesive sheet (X'-4) having a thickness of 100 μm was obtained in the same manner as in Example 1 except that the acrylic (Y'-1) was used instead of the polyurethane (X-1).

[Method for measuring loss tangent (tan δ) of adhesive layer before irradiation with active energy ray]
The release liners laminated on both sides of the adhesive sheets obtained in Examples and Comparative Examples were peeled off, and an adhesive layer was laminated to a thickness of 1 mm. cut to pieces. Using a dynamic viscoelasticity tester (manufactured by Rheometrics, trade name: Ares 2KSTD), a test piece is sandwiched between parallel discs that are the measurement part of the tester, and the temperature is 40 ° C. or 60 ° C. and the frequency The storage elastic modulus (G') and loss elastic modulus (G") at 1 Hz were measured, and the loss tangent (tan δ) was obtained by dividing the loss elastic modulus (G") by the storage elastic modulus (G') ( G″/G′).

[Method for evaluating crush resistance (method for evaluating whether components contained in the adhesive layer are extruded when force is applied to the adhesive sheet)]
The adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 5 cm×5 cm, and after peeling off the release liners laminated on both sides, an adhesive layer was laminated to a thickness of 0.5 mm. Thereafter, the adhesive sheet laminated to a thickness of 0.5 mm was press-bonded to the central portion of a release liner having a thickness of 50 μm cut into a size of 7 cm×7 cm under a pressure of 0.05 MPa for 10 seconds under a temperature environment of 23° C. to bond. rice field.

A pressure of 0.1 MPa per unit area was applied from the upper part of the above-mentioned bonded material, and the material was allowed to stand for 24 hours under temperature environments of −20° C., 5° C., and 40° C. respectively.
Next, the ratio of the change in the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing (0.5 mm) (thickness of the adhesive sheet after standing/thickness of the adhesive sheet before standing) is Evaluation was made according to the following criteria.

A: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 100% or more and less than 101% (no change).
○: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 97% or more and less than 100%.
Δ: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 93% or more and less than 97%.
x: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was less than 93%.

[Method for evaluating flexibility after irradiation with active energy ray (Method for evaluating step conformability when force is applied to the surface of the adherend after UV irradiation to bend or unevenness of the adherend)]
The adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 5 cm×5 cm, and after peeling off the release liners laminated on both sides, an adhesive layer was laminated to a thickness of 0.5 mm. Thereafter, the adhesive sheet laminated to a thickness of 0.5 mm was press-bonded to the central portion of a release liner having a thickness of 50 μm cut into a size of 7 cm×7 cm under a pressure of 0.05 MPa for 10 seconds under a temperature environment of 23° C. to bond. rice field.

The patch was left in a temperature environment of 23° C. for 60 minutes, and then irradiated with ultraviolet light having an intensity of 100 mW/cm ² for 10 seconds using an electrodeless lamp (fusion lamp H bulb).
The UV-irradiated patch was left in a temperature environment of 23° C. for 10 minutes, and then press-molded for 10 seconds under a pressure of 0.5 MPa using a hot press device heated to 80° C.
Ratio of change in thickness of the adhesive sheet after hot pressing to the thickness (0.5 mm) of the adhesive sheet before hot pressing (thickness of adhesive sheet after hot pressing/thickness of adhesive sheet before hot pressing) was evaluated according to the following criteria.

A: The ratio of the thickness of the adhesive sheet after hot pressing to the thickness of the adhesive sheet before hot pressing was less than 50%.
○: The ratio of the thickness of the adhesive sheet after hot pressing to the thickness of the adhesive sheet before hot pressing was 50% or more and less than 80%.
Δ: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 80% or more and less than 90%.
x: The ratio of the thickness of the adhesive sheet after standing to the thickness of the adhesive sheet before standing was 90% or more and less than 100% (no change).

[Method for evaluating bondability for members that do not transmit active energy rays]
The adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 10 mm in width and 10 mm in length to prepare a test sample. One release liner of the test sample was removed, and an aluminum plate with a smooth surface and a width of 15 mm, a length of 150 mm, and a thickness of 0.05 mm was pressed under pressure of 0.05 MPa for 10 seconds under a temperature environment of 23°C. , pasted together.
The patch was left in a temperature environment of 23° C. for 60 minutes, and then irradiated with ultraviolet light having an intensity of 100 mW/cm ² for 10 seconds using an electrodeless lamp (fusion lamp H bulb). At this time, the ultraviolet irradiation was performed without removing the release liner.

After the UV-irradiated pasted matter was left in a temperature environment of 23° C. for 10 minutes, the release liner was removed, and an epoxy glass plate (Shin-Kobe Denki Co., Ltd./KEL-GEF) was press-bonded for 10 minutes under pressure of 0.5 MPa using a hot press device heated to 70°C.
A test sample was prepared by heating and standing the laminate after press-bonding at 80° C. for 1 hour, leaving it at 23° C. for 30 minutes or more, and then cooling it.
The aluminum plate and epoxy glass plate used in this evaluation are opaque materials.

In the test sample (X-1), the ends of the adherend (I) and the adherend (II) were respectively chucked and pulled in a 180 degree direction using a tensile tester at a speed of 10 mm / min. The shear adhesive strength [MPa] of the test sample was determined by a tensile test.

[Storage modulus of cured product at 25°C (E' ₂₅ )]
The adhesive sheets obtained in Examples and Comparative Examples were irradiated with ultraviolet rays having an intensity of 100 mW/cm ² for 10 seconds using an electrodeless lamp (fusion lamp H bulb). At this time, the ultraviolet irradiation was performed without removing the release liner.

After the UV irradiation, the adhesive sheet was heated and left at 80° C. for 1 hour, left at 23° C. for 30 minutes or longer, and cooled. After that, the adhesive sheet after heating was punched into a test piece type 5 shape of JIS K 7127 using a dumbbell cutter, and the release liner was removed to obtain a test sample.

The dynamic viscoelasticity of the cured product (adhesive layer after curing) formed by curing the adhesive sheet was measured using a dynamic viscoelasticity measuring device (manufactured by Rheometrics, trade name: RSA-II). and the storage modulus (E′ ₂₅ ) at 25° C. at a frequency of 1.0 Hz was measured.

Claims (8)

A curable adhesive composition used for bonding two or more adherends having surfaces that do not transmit active energy rays,
The curable adhesive composition contains a polyurethane (A) having a polymerizable functional group other than a polymerizable unsaturated double bond,
The polyurethane (A) is a polyurethane obtained by reacting a polyol (a'1) containing a polycarbonate polyol having a number average molecular weight of 500 to 5000 and a polyester polyol having a number average molecular weight of 1000 to 5000 with a polyisocyanate (b'2). including (A′),
A curable adhesive composition having a loss tangent (tan δ40) at 40°C of less than 1.0 and a loss tangent (tan δ60) at 60°C of 1.0 or more. The curable adhesive composition according to Claim 1, which contains a polymerizable compound (B). 3. The curable adhesive composition according to claim 2 , wherein the polymerizable compound (B) has a photopolymerizable functional group. 4. The curable adhesive composition according to any one of claims 1 to 3 , which contains a photopolymerization initiator. An adhesive sheet having an adhesive layer formed using the curable adhesive composition according to any one of claims 1 to 4 . A laminate in which the adhesive sheet according to claim 5 is attached to an adherend. The laminate according to claim 6 , which is used for an image display device. a step [1] of applying an external stimulus to the adhesive sheet according to claim 5 ;
a step [2] of attaching the adhesive sheet to an adherend;
A method for producing a laminate comprising the step [3] of curing the adhesive sheet in this order.