JP2002146326A - Adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive sheet capable of effectively improving ease of sliding even without using inorganic particles and simultaneously improving easiness of heat peeling and peeling cleanness when the adhesive sheet is used as a heat peeling (easily heat peeling) adhesive sheet. SOLUTION: This adhesive sheet comprises a substrate and an adhesive layer arranged on at least one principal plane of the substrate and the adhesive layer is composed of an adhesive composition comprising a crystalline polymer having a polyol unit formed of a crystalline polyol as a repeating unit in the molecule and a cross-linked tackifying polymer compatible with the crystalline polymer at a higher temperature than the melting point of the crystalline polymer. The surface of the adhesive layer has unevennesses composed of the adhesive composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tacky polymer (tack)
The present invention relates to an improvement in an adhesive sheet having an adhesive layer made of an adhesive composition containing a ifying polymer and a crystalline polymer, wherein the adhesive surface of the adhesive layer has irregularities.
Such an adhesive sheet is particularly suitably used, for example, for decoration, marking, electronic parts, medical use, and the like. The adhesive sheet according to the present invention also includes a form of an adhesive article called an adhesive film or an adhesive tape.

[0002]

2. Description of the Related Art An adhesive containing a tacky polymer as a main component is also called a pressure-sensitive adhesive (adhesive), and can be easily and strongly bonded only by applying pressure. However, positioning is difficult because the adhesive surface is tacky. Therefore, in order to control the adhesiveness of an adhesive sheet (an adhesive sheet or an adhesive film having a pressure-sensitive adhesive layer),
Numerous techniques have been proposed. For example, by embossing the adhesive surface to reduce the apparent adhesiveness,
After bonding, there is a method of increasing the adhesive force by smoothing by heating (see JP-A-4-309583). In other words, during processing and alignment, the adhesive surface is kept in a concavo-convex state with a small adhesive area to the adherend, and therefore has a low overall adhesive strength, enhance re-peelability, and at the stage where the adhesive is completed, Is a method of increasing the adhesive strength.
The term “removability” refers to a property in which adhesion-peeling-re-adhesion-re-peeling is possible before final bonding is completed, and repositioning or position adjustment is easy. Removability is determined by Repositionab
Also known in the art as terms such as ility.

[0003] Further, as a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a crystalline component, International Publication No. WO97 / 4
No. 6633 (corresponding to US Pat. No. 5,889,118)
Are disclosed. In the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, a crystalline acrylate component is introduced as a continuous phase into the pressure-sensitive adhesive polymer. Even in the adhesive layer disclosed herein,
It is relatively difficult to completely eliminate tackiness without reducing adhesive strength, and usually, the adhesive surface (adhesive surface) has tackiness. Therefore, its thermally deformable shape (Ther
By making use of the momorphic property), the adhesive surface having the irregularities as the secondary shape is changed to the smooth adhesive surface that is the memory shape (primary shape), so that the processability and the ease of alignment are improved in the same manner as described above. Is increasing.

[0004] These publications do not include a description relating to improvement of so-called "slidability" (Ease of Sliding). The slidability means that before the adhesive sheet is pressed against the surface to be adhered, the surface of the adherend and the adhesive layer are in partial contact, and the adhesive sheet is easily translated along the surface to be adhered. Say what you can do. Also, there is no disclosure of using a crystalline polymer having a polyol unit formed from a crystalline polyol as a repeating unit in a molecule as a crystalline polymer (including a crystalline polyol alone). Furthermore, there is no mention of improvement in so-called thermal peelability, which facilitates peeling by heating after final bonding, during use, or after use is completed.

[0005] On the other hand, although an adhesive layer having an uneven adhesive surface is not used, it has been proposed to control the adhesive force of the adhesive surface. For example, US Pat. No. 5,192,612
No. (corresponding to Japanese Patent No. 30221664) discloses an adhesive composition (pressure-sensitive adhesive) containing a pressure-sensitive adhesive base resin (an adhesive polymer such as an acrylic polymer), a de-adhesive resin and de-adhesive particles. Adhesives) are disclosed. Specific and preferred examples of the deadhesive resin include about 3,000 to about 34
A substantially linear polycaprolactone having a molecular weight of 2,000 is disclosed. Polycaprolactone is
It is a crystalline polymer that is non-tacky at room temperature (about 15 ° C. to 30 ° C.). The above-mentioned pressure-sensitive adhesive can be bonded by pressing toward the adherend at room temperature. On the other hand, the deadhesive resin as described above, in cooperation with the deadhesive particles, effectively reduces tack on the surface of the adhesive at normal temperature, and enhances removability.
The deadhesive particles are inorganic particles such as silica. The deadhesive particles can form a non-adhesive convex portion made of the deadhesive particles on the adhesive surface. Therefore, improvement in slidability can be expected. Note that this publication does not assume that the adhesive is finally peeled off during use or after use is completed.

[0006] JP-A-2000-119624 discloses an adhesive composition comprising a specific tacky polymer and crystalline polycaprolactone. The adhesive composition disclosed herein can be bonded to an adherend by thermocompression (compression after heating or compression while heating). In addition, the adhesive polymer disclosed herein is required to have two functional groups of a hydroxy group and a phenyl group in a molecule. By the action of these functional groups, compatibility with polycaprolactone is improved. In such an adhesive, tackiness of the adhesive surface at room temperature (about 25 ° C.) can be almost eliminated by the action of a crystalline polymer having a polyol unit such as polycaprolactone in the molecule.

On the other hand, US Pat. No. 5,412,035 (corresponding to Japanese Patent Publication No. Hei 6-510548) discloses a pressure-sensitive adhesive which becomes a pressure-sensitive adhesive at at least one temperature in the range of 20 ° C. to 40 ° C. An adhesive composition, which is composed of a polymer pressure-sensitive adhesive component and a crystalline polymer, and is easily peelable by heat (pressure-sensitive adhesive) is disclosed. The crystalline polymer is usually non-tacky at room temperature and is intimately mixed with the polymer pressure-sensitive adhesive component. Melting point of crystalline polymer itself
Tm ° C., and the melting point of the crystalline polymer, Ta ° C., measured in the composition is lower than Tm, and Tm−Ta is preferably 1
C. to 9C. In addition, Tm is preferably 20 ° C to 1 ° C.
It is said to be 02 ° C. The composition has a peel strength P1 [g / cm] at a certain temperature lower than Ta,
The peel strength P2 [g / cm] at a certain temperature higher than the above becomes smaller, and the film has thermal peelability. This publication does not disclose the use of polycaprolactone as a crystalline polymer or the use of crystalline polyurethane having a crystalline polyol unit such as polycaprolactone in the main chain molecule. Therefore, the slidability cannot be improved only by the technology disclosed herein.

[0008]

By the way, it is difficult to reduce the tackiness (or tack) of the adhesive surface by including a crystalline polymer having a polyol unit formed from a crystalline polyol as a repeating unit in the molecule. Although it is advantageous for improving the slidability, there is still room for improvement. On the other hand, providing non-adhesive irregularities on the bonding surface using inorganic particles is advantageous for improving slidability. However, the presence of inorganic particles other than the adhesive component (crystalline polymer or tacky polymer) on the surface is disadvantageous for improving the adhesive strength (peeling strength after bonding). Therefore, it has been desired to effectively improve the slidability without using inorganic particles. In addition, the conventional easily peelable adhesive has a property that it can be peeled cleanly without leaving an organic component (a polymer component such as an adhesive polymer or a low molecular weight component of a crystalline polymer) of the adhesive on the adherend. Peeling cleanliness) was insufficient.

That is, an object of the present invention is to improve the slidability without using inorganic particles, and to use a heat-peelable (heat-peelable) adhesive sheet. An object of the present invention is to provide an adhesive sheet which can be improved in ease and delamination at the same time.

[0010]

SUMMARY OF THE INVENTION The present invention comprises a substrate and an adhesive layer disposed on at least one major surface of the substrate, wherein the adhesive layer comprises a crystalline polymer and a crosslinked adhesive. An adhesive sheet comprising an adhesive composition comprising a crystalline polymer, and having, on the surface of the adhesive layer, irregularities comprising the adhesive composition, wherein the crystalline polymer is a polyol unit formed from a crystalline polyol. In the molecule as a repeating unit, wherein the adhesive polymer is compatible with the crystalline polymer at a temperature higher than the melting point of the crystalline polymer, providing an adhesive sheet, Solve the problem.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION [Action] The adhesive composition used in the present invention comprises a crystalline polymer and a crosslinked adhesive polymer, and the crystalline polymer is formed from a crystalline polyol. It is characterized in that it has a polyol unit as a repeating unit in the molecule and that the adhesive polymer is compatible with the crystalline polymer at a temperature higher than the melting point of the crystalline polymer. The unevenness of the adhesive surface formed from such an adhesive composition effectively reduces the tack to the adherend surface, and the adhesive sheet is adhered before the adhesive sheet is pressed against the adherend surface of the adherend. Partial contact between the surface and the adhesive layer is maintained, and slidability can be effectively improved. Such a slidability improvement effect can be exhibited without using inorganic particles.

Further, since the irregularities on the adhesive surface are made of an adhesive composition, when the adhesive sheet is pressed against the adherend surface, the adhesive surface has a sufficient peel strength (for example, at room temperature, about 2 ° C).
180 ° peel strength at 5 ° C and 300 mm / min is 15 N /
(25 mm or more). Furthermore, since the adhesive surface irregularities are easily deformed by pressing the adhesive sheet after or while heating, the contact area of the adhesive surface with the adhered surface (for example, defined by the area contact ratio described below). Can also be effectively increased. On the other hand, since the above-mentioned adhesive composition contains the above-mentioned crystalline polymer and the above-mentioned adhesive polymer, the adhesive sheet of the present invention is used as a heat-peelable (heat-peelable) adhesive sheet. When used, the ease of thermal stripping and the cleanability of stripping can be simultaneously improved effectively.

(Crystalline Polymer) The crystalline polymer used in the present invention usually has a polyol unit formed from a crystalline polyol as a repeating unit in the main chain molecule. When the crystalline polyol unit is present in the main chain molecule instead of the side chain, the relatively short molecular chain (ie,
Even with a crystalline polyol unit formed from a polyol compound (polyol) having a relatively low molecular weight, it is easy to increase the crystallinity and crystallization rate. Therefore,
This is advantageous for increasing the crystallinity and crystallization rate of the polymer without impairing the compatibility with the adhesive polymer.

In the present specification, "polyol"
The term refers to a polymer or oligomer compound that is substantially non-tacky at room temperature (about 25 ° C.) and has two or more hydroxyl groups in the molecule. “Crystallinity” means a property that can be melted by heating.
The melting point of a crystalline polymer is usually determined by the melting point of a polyol contained as a repeating unit. Melting point is usually 30 ~
70 ° C., preferably 35-65 ° C., particularly preferably 4 ° C.
0-60 ° C.

The molecular weight of the crystalline polymer may be within a range in which a predetermined adhesive force is exhibited, and the weight average molecular weight is usually 5,000 to 200,000, preferably 10,000.
0 to 150,000, particularly preferably 15,000 to 1
It is in the range of 30,000. If the molecular weight is too small, slidability and peel cleanliness may decrease,
On the other hand, if it is too large, the compatibility with the adhesive polymer may be reduced, and a predetermined effect (such as improvement in ease of thermal peeling) may not be obtained. In addition, in this specification, "molecular weight" is a styrene conversion molecular weight measured using GPC.

The crystalline polymer as described above is preferably a crystalline polyol such as a polyester polyol such as polycaprolactone, a polyether polyol or a polycarbonate polyol, or a raw material composition containing these polyols and a diisocyanate compound. It is a crystalline polyurethane obtained by polymerizing a product. One or two or more selected from the group consisting of these crystalline polymers can be used in combination. The content ratio of the crystalline polymer is determined in an optimum range for obtaining a predetermined effect. For example, if the amount of the crystalline polymer is too small, the slidability may not be effectively improved. Conversely, if the amount of the crystalline polymer is too large, the adhesive strength (peel strength) may be reduced.
May decrease. From such a viewpoint, the content ratio of the crystalline polymer is 4 to 4 based on the total mass of the composition.
It is preferably in the range of 55% by mass, and 5 to 50% by mass.
Is particularly preferred.

(Polyurethane) One of the preferred crystalline polymers is polyurethane having a crystalline polyol unit in the molecule. In such a polyurethane, it is extremely easy to freely control the recrystallization speed (or the recrystallization completion time), and it is possible to effectively enhance the heat peelability and the peel cleanliness. That is, when such a polyurethane is used, the molecular weight of the crystalline polyol unit can be adjusted to control the recrystallization rate (or recrystallization completion time). Therefore, in the crystalline polyol unit which is a crystalline polymer portion,
Several crystalline units can be linked by urethane bonds, while keeping the molecular weight per unit relatively small. As a result, the molecular weight of the entire polyurethane can be made as large as possible, and the peeling cleanability can be effectively improved.
On the other hand, since the molecular weight per crystalline unit can be made relatively small, the recrystallization speed is slow (small).
can do. When the recrystallization speed is low, the recrystallization completion time becomes long, so that when the adhesive is used as an adhesive which is easy to thermally peel, the easy peel time can be increased.

As mentioned above, the polyol units in the polyurethane are formed from crystalline polyols. That is,
By reacting with an isocyanate compound such as diisocyanate, the crystalline polyol is incorporated into the urethane molecule to form a crystalline polyol unit as a repeating unit. As the crystalline polyol, for example, a crystalline polyol is selected from polyester polyol, polyether polyol, polycarbonate polyol and the like. A preferable polyester polyol is polycaprolactone from the viewpoint of easily controlling the crystallinity (crystallinity and crystallization rate) of the polyurethane. From the same viewpoint, a preferable polyether polyol is polytetramethylene glycol. The polyol compound may be one kind or a mixture of two or more kinds.

The weight average molecular weight of the crystalline polyol used as a raw material for the polyurethane is usually 1,000 to 200,000.
0, preferably 1,500 to 50,000, particularly preferably 3,000 to 15,000. If the weight average molecular weight is too small, the crystallinity may not be effectively increased, and the effects such as slidability may be reduced. On the other hand, if the molecular weight is too large, it may be difficult to control the crystallization speed, the compatibility with the adhesive polymer may be reduced, and the ease of heat peeling and the cleanability of peeling may be reduced.

The isocyanate compound is usually a diisocyanate having two isocyanate groups in the molecule. The diisocyanate is, for example, one selected from the group consisting of isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), hydrogenated MDI, tolylene diisocyanate (TDI), and 1,6-hexanediol diisocyanate (HDDI).
Mixtures containing one or more diisocyanates can be used. Further, a compound having a biuret structure or an isocyanurate structure, which is obtained by reacting the above-described diisocyanates, can also be used. In order to effectively enhance the heat release property, it is preferable to use an aliphatic diisocyanate such as 1,6-hexanediol diisocyanate and isophorone diisocyanate.

In order to further facilitate the control of the crystallinity, the starting material used for the polymerization of the polyurethane does not contain a chain extender (short-chain diol) and is substantially composed of a crystalline polyol and a diisocyanate. Is preferred.
In order to deactivate the terminal isocyanate residue of the polyurethane molecule, a lower monohydric alcohol may be used. In this case, a monohydric alcohol residue is introduced into the end of the polyurethane molecule, but the molecular main chain other than the end substantially comprises a polymerized unit formed from a crystalline polyol and a diisocyanate.

The polyurethane is formed (polymerized) by, for example, heating a liquid formed by dissolving or dispersing the starting materials in a solvent with stirring. Examples of the solvent include compounds that do not contain active hydrogen, such as ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, aromatic hydrocarbon solvents such as toluene and xylene, and ester solvents such as ethyl acetate. . The mixing ratio between the polyol and the isocyanate is usually the number of moles (H1) of the OH group contained in the total mass of the polyol,
It is represented by the ratio (H1: N1) to the number of moles (N1) of the NCO group contained in the isocyanate compound of the total mass, and this ratio may be usually 1: 1 to 1: 1.60. Also,
A catalyst used for usual polymerization of polyurethane, for example, dibutyltin laurate can also be used. When a polyurethane is obtained by polymerizing a polyurethane in a solvent as described above, a solution (or dispersion) containing the polyurethane is
As it is, it can be used as a polyurethane composition for an adhesive for producing the adhesive composition of the present invention.

In a composition containing a tacky polymer and a polyurethane having a crystalline polyol unit in the molecule, the tackiness can be almost eliminated at room temperature by crystallization of the polyol unit. However, by applying pressure to the adherend at room temperature or while heating, a predetermined adhesive force can be developed. If stronger bonding is required, thermocompression bonding can be used.

(Polycaprolactone) As described above, another preferred example of the crystalline polymer is polycaprolactone. Polycaprolactone can be used as a raw material for polyurethane as described above, but can also be used as a crystalline polymer. The polycaprolactone used in the present invention refers to (i) polycaprolactone obtained by polymerizing a starting material containing caprolactone, or (ii) a polymerized unit (unit) obtained by ring-opening polymerization of caprolactone. The polycaprolactone contained within. In a composition containing a sticky polymer and polycaprolactone, the tackiness can be almost eliminated at room temperature by crystallization of polycaprolactone. However, by applying pressure to the adherend at room temperature or while heating, a predetermined adhesive force can be developed. If stronger bonding is required, thermocompression bonding can be used.

(Tacky Polymer) The tacky polymer used in the present invention is a polymer which exhibits tackiness at ordinary temperature (about 25 ° C.), and when heated to a temperature not lower than the melting point of the crystalline polymer, the crystalline polymer Compatible with. Also,
The tacky polymer is preferably crosslinkable. When the adhesive composition is used as a heat-peelable adhesive, the adhesive polymer is particularly preferably crosslinked.

Whether the tacky polymer is compatible with the crystalline polymer when heated to a temperature equal to or higher than the melting point of the crystalline polyol is determined by the transparency of the adhesive composition, that is, the change (decrease) in haze. it can. For example, it is composed of the adhesive composition used in the present invention and has a thickness of 20 to 60.
For a film adhesive in the range of μm (film-like adhesive), when heated above the melting point of the crystalline polyol,
Compare with the case where the temperature is lower than the melting point (normal temperature, about 25 ° C. is good).
At room temperature, the crystalline polymer usually forms a plurality of fine crystals, and the crystalline polymer is dispersed in a matrix containing a sticky polymer, so that the transparency is relatively high,
The haze measured using a color difference meter is at least 5% or more (usually 20% or less). On the other hand, above the melting point of the polyol, the crystalline polymer melts, and in the state where the crystalline polymer and the tacky polymer are compatible, haze is reduced and the film adhesive becomes almost transparent. Further, even if the crystalline polymer is melted, the haze hardly changes when the crystalline polymer and the tacky polymer are not compatible. In such a case, the smaller the haze, the better the compatibility. Therefore, the haze measured using a color difference meter is
When the crystalline polymer and the tacky polymer are compatible, the content is preferably 3% or less, particularly preferably 2% or less.

Further, the compatibility of these two polymers can be easily determined by whether or not the solution containing the crystalline polymer and the tacky polymer is transparent. That is, one of the prerequisites for good compatibility between the adhesive polymer and the crystalline polymer is a transparent first solution containing the dissolved adhesive polymer and a transparent first solution containing the crystalline polymer dissolved therein. When it is mixed with a suitable second solution, it becomes a transparent mixed solution.

Further, it can be confirmed by examining the transmittance of polarized light using a polarizing microscope. As is well known, when the polarization axes of two polarizing plates are orthogonal to each other, light is not transmitted, and the visual field is almost completely dark. A film adhesive made of the adhesive composition of the present invention is placed between the two polarizing plates orthogonal to each other in this manner, and observed. At room temperature, the microcrystals of the crystalline polymer rotate the plane of polarization of the light incident on the film adhesive and transmit the two polarizing plates. Since the directions of the crystal axes are usually random, there are a mixture of crystals that transmit the two polarizing plates by rotating the polarization plane of light by exactly 90 degrees and crystals that do not easily pass light.
The smaller the crystallites of the crystalline polymer are dispersed, the higher the compatibility between the crystalline polymer and the adhesive polymer. Therefore, the higher the compatibility of the polymers with each other, the smaller the crystal size, and the microscope visual field (100 to 200 times)
Inside, the whole film looks light and bright. When the compatibility of the polymers is low, the crystal size is large and the crystals are visible as bright dots scattered on a dark base. In the state where the crystalline polymer is melted and the tacky polymer and the crystalline polymer are compatible with each other, the mixture of these polymers contained in the film adhesive is optically isotropic. It becomes darker than that.

Examples of the adhesive polymer include acrylic polymers and nitrile-butadiene copolymers (NBR).
Styrene-butadiene copolymers (SBR, etc.),
Non-crystalline polyurethane, silicone-based polymer and the like. The adhesive polymer is composed of one of these polymers alone or a mixture of two or more thereof.

When the polyol unit of the crystalline polymer is polycaprolactone, that is, the crystalline polymer is polycaprolactone or a polycaprolactone polyurethane having a polyol unit formed from polycaprolactone as a repeating unit in the molecule (hereinafter, referred to as polycaprolactone polyurethane).
It may be called "polycaprolactone polymer". In the case of (1), in order to increase the compatibility between the crystalline polymer and the adhesive polymer, for example, the following adhesive polymer is preferable. One of the suitable adhesive polymers is a polymer having (a) a hydroxy group and (b) a phenyl group as essential functional groups in the molecule. When such an adhesive polymer has an alkyl group having 4 to 10 carbon atoms in addition to the functional groups (a) and (b), the adhesive force (peel strength) by pressure bonding at normal temperature (about 25 ° C.) ) Can be effectively increased, and the adhesive sheet of the present invention can be used as a pressure-sensitive adhesive sheet having a relatively high adhesive force.

On the other hand, in order to impart cross-linkability, it is preferable to further have a cross-linking functional group as an essential functional group. The cross-linking functional group is a functional group capable of performing a cross-linking reaction by irradiation of electromagnetic waves (light, ultraviolet rays, etc.) or an electron beam, or heating, and is generally a functional group that reacts with a cross-linking component contained in the adhesive composition. Further, the adhesive polymers may be directly crosslinkable via a crosslinkable functional group. Details of the crosslinking functional group and the crosslinking component will be described later.

The polymer containing the essential functional group in the molecule is a mixed monomer containing a monomer having a hydroxy group in the molecule, a monomer having a phenyl group in the molecule, and a monomer having a crosslinking functional group in the molecule. It can be obtained by polymerization using (starting monomer). Alternatively, after polymerization, a carboxyl group in the molecule may be reacted to be converted into a hydroxy group and a phenyl group.

Here, a preferred example of an acrylic polymer which can be used in combination with a polycaprolactone polymer in the present invention will be described. Such polymers include (A) a (meth) acrylic monomer having a hydroxy group in the molecule, (B) a (meth) acrylic monomer having a phenyl group in the molecule, and (C) a crosslinking functional group in the molecule. (Meth) acrylic monomer having (D)
An acrylic polymer obtained by polymerizing a mixed monomer containing an alkyl acrylate having an alkyl group having 4 to 10 carbon atoms. Such polymers are prepared in the usual way,
For example, it can be prepared by copolymerization by solution polymerization or the like.

As the component (A), for example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, hydroxy- Examples thereof include 3-phenoxypropyl acrylate. As the component (A), a monomer containing both a hydroxy group and a phenyl group in the molecule, such as 2-hydroxy-3-phenoxypropyl acrylate, is suitable. This makes it possible to particularly effectively increase the compatibility of the adhesive polymer with the polyol. As the component (B), for example, those having a phenoxy group as a phenyl group such as phenoxyethyl acrylate and phenoxypropyl acrylate are preferable.

As the component (C), those having a thermally crosslinkable functional group such as an unsaturated acid such as (meth) acrylic acid and an epoxy group-containing (meth) acrylic monomer such as glycidyl (meth) acrylate are used. it can. Also, an unsaturated double bond such as acryloylbenzophenone,
It is also possible to use a (meth) acrylic monomer having the photocrosslinkable functional group in the molecule to obtain a photocrosslinkable adhesive polymer. The component (C) may include both the heat crosslinkable functional group and the photocrosslinkable functional group, and may be crosslinkable by both heat and light. Examples of the component (D) include n-butyl acrylate, isobutyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, and the like. The above (D)
The component does not have the functional groups (a) to (c) in the molecule.

The total ratio (% by mass) of the units derived from the components (A) and (B) to the total polymerized units of the above-mentioned adhesive polymer is usually from 40 to 90% by mass, preferably from 90 to 90% by mass. It is 41 to 85% by mass, particularly preferably 42 to 80% by mass. If the number of the units containing the two functional groups is too small, the compatibility with the crystalline polymer may be reduced. Conversely, if the number of the units having the other functional groups is too small, the crosslinkability or the adhesiveness may be too small. And the predetermined performance as described above may not be effectively enhanced. For example, a decrease in crosslinkability may impair the adhesive residue prevention effect.
In addition, a decrease in the tackiness of the tacky polymer itself may result in adhesion by pressure bonding between the adherend and the adherend, that is, there is a possibility that the pressure-bonding performance is reduced. When importance is placed on such pressure-bonding performance, the total ratio of units derived from the components (A) and (B) is preferably in the range of 42 to 60% by mass.

The proportion of the unit derived from the component (B) in the total polymerized units of the adhesive polymer is at least 0.5 mol%, preferably at least 1 mol%, particularly preferably 5 to 25 mol%.
Mol%. If the number of units derived from the component (B) is too small, the compatibility with the crystalline polymer may be reduced. Conversely, if the number of units derived from the component (B) is too large, the pressure-bonding performance may be reduced. . On the other hand, the total ratio (mass percent) of the units derived from the component (C) in the total polymerized units of the adhesive polymer is usually 0.5 to 1%.
It is from 5% by weight, preferably from 0.7 to 10% by weight, particularly preferably from 1 to 7% by weight.

As long as the effects of the present invention are not impaired, the above-mentioned adhesive polymer may be used in combination with a polymer having no essential functional group (hydroxy group, phenyl group, etc.) and a polymer having no such functional group. it can. However, the proportion of the polymer containing these essential functional groups in the entire adhesive polymer (total mass) is usually 50% by mass or more, preferably 60% by mass or more, and particularly preferably 70% by mass.
That is all.

The molecular weight of the pressure-sensitive adhesive polymer used in the present invention may be within a range in which a predetermined adhesive force is exhibited, and is usually 10,000 to 1,000,000 in terms of weight average molecular weight.
It is in the range of 0. Also, like conventional pressure-sensitive adhesives,
Tackifiers can also be used with the tacky polymer.

(Crosslinking Functional Group) The crosslinking functional group of the adhesive polymer is a functional group different from (a) a hydroxy group,
Those that can react with the thermal crosslinking component are preferred. Preferably, the crosslinking functional group contains at least one of a carboxyl group and an epoxy group. Also, both may be included at the same time. In such a case, a suitable thermal crosslinking component is a compound having in its molecule two or more crosslinking functional groups capable of reacting with a carboxyl group and / or an epoxy group, which are crosslinking functional groups of the adhesive polymer. It is not particularly limited. Such compounds are usually monomers or oligomers.

Preferred combinations of the crosslinking functional group of the adhesive polymer and the thermal crosslinking component include the following. (1) When the crosslinking functional group is a carboxyl group, a bisamide-based crosslinking agent or an epoxy resin is suitable as the thermal crosslinking component. (2) When the crosslinking functional group is an epoxy group, rosin having a carboxyl group in the molecule (carboxyl rosin) is suitable as the thermal crosslinking component. Regardless of whether the crosslinking functional group is a carboxyl group or an epoxy group, thermal crosslinking can be performed without hindering the compatibilizing action of the hydroxyl group and the phenyl group of the adhesive polymer with the polyol. In addition, it is easy to carry out a sufficient crosslinking density by a thermal crosslinking reaction to enhance the heat resistance as an adhesive and the effect of preventing adhesive residue. In the case of the above (1),
A carboxyl rosin can be used in combination, and in the above case, an epoxy resin and / or a bisamide-based crosslinking agent can be used in combination. When the crosslinking functional group is a carboxyl group, an isocyanate-based crosslinking agent can be used as long as the effects of the present invention are not impaired.

(Crosslinking Component) The epoxy resin reacts with the carboxyl group of the adhesive polymer and acts to thermally crosslink the adhesive polymer. As the epoxy resin, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin and the like can be used. The epoxy equivalent of the epoxy resin is usually 70 to 40.
0, preferably 80-300. As the bisamide-based crosslinking agent, for example, a dibasic acid bisaziridine derivative such as isophthaloylbis (2-methylaziridine) can be used. The bisamide-based crosslinking agent is particularly preferable because it can react with the adhesive polymer having a carboxyl group at a relatively low temperature and can easily obtain a sufficient crosslinking density.

On the other hand, when the adhesive polymer has an epoxy group in the molecule, it is preferably carboxyl rosin as a crosslinking component. Carboxyl rosin has a carboxyl group in the molecule and reacts with the adhesive polymer to act to thermally crosslink the adhesive polymer. As the carboxyl rosin, gum rosin, wood rosin, tall oil rosin, or those obtained by chemically modifying them (for example, polymerized rosin) can be used. In addition, the carboxyl rosin can be used alone or as a mixture of two or more, and a rosin having substantially no carboxyl group can be used in combination as long as the effect of the present invention is not impaired.

When the above-mentioned cross-linking component is used, its proportion in the whole adhesive (total mass) is usually 0.01 to 20% by mass or more, preferably 0.05 to 10% by mass. Further, a reaction accelerator for a cross-linking component such as an epoxy resin may be added. Thereby, the crosslinking condition by heating can be made mild. The crosslinking component is not limited to those described above, and can be selected according to the type of crosslinking functional group and crosslinking conditions.

(Method of Manufacturing Adhesive Composition) The adhesive composition used in the present invention can be prepared by uniformly mixing the respective raw materials by a usual mixing operation. For example, an adhesive polymer, a crystalline polymer, a cross-linking agent, a solvent, and the like are mixed by a mixing device such as a homomixer or a planetary mixer, and each material is uniformly dissolved or dispersed to prepare a liquid composition. it can. The crystalline polyurethane can be prepared as described above, and when polymerized in a solvent,
The solution containing the polymerized crystalline polyurethane can be used as a raw material as it is.

This liquid composition is usually prepared by mixing a first solution containing the adhesive polymer dissolved therein and a second solution containing the crystalline polymer dissolved therein. A liquid (coating material) containing a homogeneous polymer dissolved uniformly is prepared and dried to form an adhesive layer made of an adhesive composition. In this manner, a unique morphology (interconnection structure) between the crystalline polymer and the adhesive polymer having good compatibility with the crystalline polymer can be formed, and the above-mentioned performance (non-adhesiveness and high adhesion at room temperature) can be obtained. ) Can be exerted particularly effectively. In addition,
When adding a crosslinking component, usually, a third solution containing the crosslinking component is added to the coating material.

(Manufacturing Method of Adhesive Sheet) A coating containing the adhesive composition obtained as described above is applied and dried to form an adhesive layer, whereby an adhesive sheet can be manufactured. For example, as will be described in detail later, a coating of an adhesive composition is applied to a release surface of a liner having a release surface provided with irregularities having a predetermined roughness dimension and dried to form an adhesive layer. On the surface (adhesive surface) of the adhesive layer thus formed, irregularities (positive irregularities) on which the irregularities (negative irregularities) of the liner release surface are transferred are formed. A base material is overlaid on the adhesive layer and pressed to complete the adhesive sheet of the present invention. Further, the adhesive layer is formed by applying and drying the surface (or both front and back surfaces) of the base material, and a liner having an uneven release surface is pressed against the adhesive layer, and the negative unevenness of the liner is applied to the adhesive surface of the adhesive layer. Is formed, and the adhesive sheet of the present invention can be completed. The irregularities may be arranged with a regularly repeated pattern on the surface on which they are arranged (adhesive surface or liner release surface).
Irregularities made of roughness having an irregular pattern may be used.

Drying for forming the adhesive layer is usually 60 to
It is performed at a temperature of 180 ° C. The drying time is usually several tens of seconds to several minutes. The thickness of the adhesive layer is usually 5 to 1,000.
0 μm, preferably 10-500 μm, particularly preferably 15 μm
１００100 μm. The coating means includes a knife coater,
Known means such as a roll coater, a die coater, and a bar coater can be used.

The roughness of the adhesive surface of the adhesive layer can be appropriately determined as long as the slidability can be improved. For example, the maximum depth is usually 1 to 25 μm, preferably 1.5 to
It is 20 μm, particularly preferably 2 to 15 μm. If the maximum depth is too small, the slidability may not be effectively improved. On the other hand, if the maximum depth is too large, only the pressure bonding at room temperature (about 25 ° C.) may cause a gap between the adhesive surface and the adherend surface. A relatively large gap tends to remain. Such a gap usually forms a communication passage communicating with the outside, so that moisture and the like easily enter from the outside between the bonding surface and the adhered surface. For example, the infiltration of moisture can occur during use of the bonded adhesive sheet.
There is a possibility that the adhesive sheet may swell. Therefore, it is preferable to prevent such a gap (communication path) from remaining. However, the problem due to the relatively large roughness such as the gap is that the adhesive sheet is heated, or if it is permitted to use the adhesive sheet while heating, the unevenness is easily deformed by the heat treatment. Can be solved.

Center line average roughness (Ra) of irregularities on the adhesive surface
Is usually 0.5-20 μm, preferably 0.6-15 μm
m, particularly preferably 0.7 to 10 μm. If Ra is too small, slidability may not be effectively improved, while if too large, a relatively large gap tends to remain between the bonding surface and the adhered surface as described above. However, the problem caused by the relatively large roughness is that, as described above, if the adhesive sheet is allowed to be used after being heated or while being heated, the unevenness can be easily deformed by a heat treatment. Can be solved.

When the roughness of the liner release surface is transferred to the adhesive surface of the adhesive layer as described above, the roughness of the adhesive surface of the adhesive layer is determined by the roughness of the liner release surface. You. That is, if the release surface having the above Ra or the liner having the release surface having the convex portion having the maximum height corresponding to the maximum depth is used, the bonding surface having the maximum depth and the Ra as described above is obtained. It can be formed on an adhesive layer.

Further, the roughness of the bonding surface can be defined by the contact area of the bonding surface. The contact area is usually defined by an area contact ratio measured as follows. First, the adhesive sheet is pressed against the surface of the slide glass by three reciprocations with a 2 kg roller to obtain a measurement sample. Immediately after the pressure bonding, white light is illuminated from the side opposite to the side to which the adhesive sheet of the slide glass is adhered, and observed through a polarizing plate. The area where the adhesive and the glass surface are in contact appears black, and the non-contact area appears whitish. The observation result is analyzed using an image processing apparatus, and the area of the contact region and the area of the entire observation visual field are measured. The ratio between the two (the area of the contact region and the area of the entire observation visual field) is expressed as a percentage, and this is referred to as “area contact ratio”.

The area contact ratio thus measured is a value measured when the unevenness is not easily deformed by the heat treatment, and is usually 20 to 95%, preferably 22 to 90%, particularly preferably 25 to 90%. 85%. If the area contact ratio is too large, the slidability may not be effectively improved.On the other hand, if the area contact ratio is too small, the adhesive force immediately after the pressure bonding may not be increased, and the initial relatively large roughness may be obtained. May cause problems. However,
As described above, such a problem can be solved by heat treatment when heat treatment of the adhesive sheet is permitted.

The liner is usually formed from paper or plastic film. The paper liner is usually formed by laminating a release coat (release layer) such as a polyethylene coat or a silicone coat on the surface of paper. When laminating a silicone release coat, usually, an undercoat such as a clay coat or a polyethylene coat is laminated on paper, and then a release coat is laminated. Preferably it is a paper liner. The paper liner has a relatively small dimensional roughness formed by paper fibers on the release surface (preferably 10 μm
Below). Therefore, unevenness having a relatively small roughness dimension is given to the bonding surface, and the problem caused by the relatively large roughness can be easily solved even when the heat treatment is not allowed.

As the base material of the adhesive sheet, a base material (support) conventionally used for the adhesive sheet can be used.
For example, paper, metal film, polymer film and the like can be used. As the polymer of the film, polyimide,
Synthetic polymers such as polyvinyl chloride, acrylic polymers, polyesters (such as PET), polyurethane, and polyolefin polymers (including ethylene copolymers such as ethylene-acrylic acid copolymer) can be used. Also,
A retroreflective sheet may be used as a substrate. The thickness of the substrate is usually 5 to 500 μm, preferably 10 to 300 μm.
μm. The substrate may be one that transmits visible light or ultraviolet light, or one that reflects light. Further, it may be colored or decorated by printing or the like. In that case, the adhesive sheet of the present invention is useful as a decorative sheet or a marking film.

As long as the effects of the present invention are not impaired, conventionally known additives can be added to the adhesive layer. For example, a viscosity modifier, an antifoaming agent, a leveling agent, an ultraviolet absorber, an antioxidant, a pigment, a fungicide, an elastic microsphere made of an adhesive polymer or a non-adhesive rubber polymer, a tackifier (Tackifier) ) And catalysts for accelerating the crosslinking reaction.

(Adhesive Sheet with Easy Thermal Separation) The adhesive sheet of the present invention can be used as an adhesive sheet with easy thermal peelability (thermally peelable adhesive sheet). The adhesive layer of the adhesive sheet of the present invention has the following features. That is, [1] the crystalline polymer and the adhesive polymer are contained, and [2] the adhesive polymer is compatible with the crystalline polymer when heated to a temperature equal to or higher than the melting point of the crystalline polymer. And [3] the adhesive polymer is crosslinked. Thereby, when desired, heating to a predetermined temperature is performed to make the peeling state in which the peel strength is reduced to a value lower than the value before heating, to enhance the thermal peelability, and to maintain the peelable state. It is possible to extend the easy peeling time to a predetermined time, to be able to peel without leaving adhesive on the adherend, to enhance the cleanliness of peeling, and to reapply by peeling and pressing against the adherend. It is possible to provide a heat-peelable adhesive sheet capable of improving re-adhesiveness so that it can be adhered.

In the adhesive composition used in the present invention, in particular, since the tacky polymer is compatible with the molten crystalline polymer, it is advantageous for delaying recrystallization of the crystalline polymer after heating. is there. Also, the melting and recrystallization of such a crystalline polymer in the composition is a substantially reversible physical reaction (phenomenon). Thus, after heating, when re-bonding or after re-bonding, the composition returns to substantially the same phase state as before heating. Therefore, it can be re-bonded in the same manner as when it is used initially (first). Further, after re-adhesion, it can be peeled off by heating again. In the case where the heat-peelable adhesive sheet according to the present invention contains a relatively large amount of the adhesive polymer, it can be adhered only by pressure bonding at room temperature (about 15 to 30 ° C.). In the case where the amount of the adhesive polymer is relatively small, or in the case where the adhesive polymer is adhered to an adherend that is difficult to adhere, the adhesive can be applied by thermocompression bonding. Further, after the heat-peeling, the adhesive may be re-adhered to the adherend before the adhesive is cooled.

Further, since the cohesive force is effectively increased by the crosslinking, the adhesive polymer is effectively prevented from remaining on the adherend during peeling. On the other hand, in the easy peeling state,
The crystalline polymer is compatible with the crosslinked sticky polymer. Therefore, such as hinder the melting-recrystallization reaction,
The adhesive residue as the whole adhesive layer can be effectively prevented without requiring the crosslinking of the crystalline polymer itself. From such a viewpoint, when the adhesive composition further contains a crosslinking agent (crosslinking component), it is preferable to use a crosslinking component that does not substantially react chemically with the crystalline polymer.

In order to obtain the effects of the present invention as described above, the content of the tacky polymer is in the range of 50 to 95% by mass based on the total mass of the composition. If the content of the adhesive polymer is less than 50% by mass, the above effects may not be particularly obtained. On the other hand, if it exceeds 95% by mass, the above effects may not be obtained.

On the other hand, the content ratio of the crystalline polymer is in the range of 4 to 49% by mass based on the total mass of the composition. If the content of the crystalline polymer is less than 4% by mass, the above effects (1) to (4) may not be obtained, and
If it exceeds 9% by mass, the above-described effects may not be obtained. From these discussions, the content ratio of the adhesive polymer is preferably 52 to 94% by mass, particularly preferably 55 to 94% by mass.
９０90% by mass. The content ratio of the crystalline polymer is preferably 5 to 47% by mass, particularly preferably 9 to 44% by mass.

(Method of Using Adhesive Sheet) When the adhesive sheet according to the present invention is used by adhering it to an appropriate adherend, for example, after being laminated on the adherend, 1 to 50 kg / c
m ² (approximately 0.1 to 4.9 MPa).
The bonding can be completed using a crimping operation. Further, at the time of pressure bonding, the adhesive strength can be increased by heating and cooling (natural cooling). Examples of the adherend include (1) metals such as aluminum, stainless steel, copper, and zinc steel sheets, (2) resins such as polyimide, acrylic resin, polyurethane, melamine resin, epoxy resin, and vinyl chloride; and (3) ceramics and glass. A surface formed from an inorganic oxide material or the like, that is, a material having an adhered surface can be used. Also,
What has a painted surface as an attachment surface can also be used.

In the heat-peelable adhesive sheet according to the present invention, slidability can be improved. Therefore, positioning with respect to the adherend is particularly easy in the bonding operation. On the other hand, after the positioning, it can be bonded by pressing directly or by heating and pressing and cooling. Such an easily positionable and pressure-bondable adhesive sheet has an adhesive surface having a relatively large area (usually 400 cm ² or more), such as a decorative sheet (decorative sheet) for interior or exterior, It can be suitably used as a retroreflective sheet for large road signs. Further, since it can be adhered (adhered) to an adherend with a desired peel strength, and can be peeled off by heating at a desired time without adhesive residue, it can be used as an application tape (or film).

When performing thermal peeling, usually 60 to 120 ° C.
At this temperature, heating may be performed for 30 seconds to 5 minutes. In addition, after heating for peeling, it has a peeling easy time of at least 5 minutes or more. The easy peeling state can be maintained even after the adherend and the adhesive layer are cooled to around room temperature (about 25 ° C.), but the adhesive strength (peeling strength) increases again about 15 minutes after cooling, Preferably, the re-adhesion can be completed. In the heat peeling operation, a heating device such as an iron, a dryer, and an infrared (far infrared) lamp can be used to heat the adherend and / or the adhesive sheet. Also,
When the substrate contains a metal foil, the adhesive sheet can be heated by an electromagnetic induction heating method. Further, heating can be performed using a liquid or steam as a heat medium.

The peel strength of the adhesive sheet is a value measured at a peeling speed of 180 ° and a peeling speed of 300 mm / min before heating for peeling, and preferably exceeds 15 N / 25 mm.
Particularly preferably, it is in the range of 16 to 40 N / 25 mm. Further, the optimum range of the peel strength at the time of the thermal peeling operation can be appropriately determined depending on the mechanical strength (elastic modulus, elongation at break, etc.) of the base material and the peeling operation conditions (peeling speed). From the viewpoint of performing the peeling operation promptly, the value measured at a peeling speed of 180 ° and a peeling speed of 300 mm / min is preferably 15 N / 25 mm or less.

[0066]

EXAMPLES Next, examples of the present invention will be described. All "parts" shown below are parts by mass. (Examples 1-8) 1. Preparation of Adhesive Polymer The adhesive polymer used in each example was prepared as follows. First, 9.0 parts of phenoxyethyl acrylate,
A mixed monomer consisting of 4.5 parts of 2-hydroxy-3-phenoxypropyl acrylate, 15.0 parts of butyl acrylate and 1.5 parts of acrylic acid (30 parts in total) was mixed with 59.5 parts of ethyl acetate and 10 parts of 2-butanone. It was dissolved in a solvent consisting of 5 parts to form a monomer solution. Next, 0.15 parts of azobis 2,4-dimethylvaleronitrile was added as an initiator to this monomer solution. The monomer solution was added at 45 ° C. for 2 hours, and further at 65 ° C. for 3 hours,
The polymerization reaction was carried out under a nitrogen atmosphere to obtain an adhesive polymer solution having a solid content of 30%.

2. Polycaprolactone polyurethane
In some examples, polyurethane prepared as follows was used as a crystalline polymer. The crystalline polyol used for preparing the polyurethane was polycaprolactone (Placcel: manufactured by Daicel Chemical Industries, Ltd.).
(Registered trademark) 240, Mw = 11,000, Mw / Mn =
1.9). Polycaprolactone and isophorone diisocyanate (IPDI) were mixed at a molar ratio of 2: 3 and polymerized in a toluene solvent. In the polymerization operation, first, 0.5% by mass of dibutyltin dilaurate (catalyst) based on polycaprolactone was added to the toluene solution, and the solution was heated at 80 ° C. for 5 hours under a nitrogen atmosphere. Thereafter, 10% by mass of n-propyl alcohol based on polycaprolactone was added to the above solution, and the mixture was further heated at 80 ° C. for 1 hour to complete the polymerization, thereby obtaining a polyurethane solution having a solid content of 30%.
Weight average molecular weight (Mw) of polyurethane obtained by polymerization =
120,000, molecular weight distribution (Mw / Mn) = 6.0.

[0068] 3. Crystalline Polycaprolactone In some other embodiments, the crystalline polymer was polycaprolactone (Placcel® H1P, Mw = 25.0, manufactured by Daicel Chemical Industries, Ltd.).
00, Mw / Mn = 2.1). A solution of this polycaprolactone in toluene (non-volatile concentration = 35% by mass)
Was used to prepare an adhesive composition solution as described below.

[0069] 4. Preparation of Adhesive Composition Solution (Examples 1 to 3)
8) The adhesive polymer solution and the crystalline polyurethane solution respectively prepared as described above are mixed so that the mass ratio of non-volatile components becomes 80:20, and isophthalic acid is added to the mixed solution as a crosslinking agent. 0.2 parts by mass of loylbis (2-methylaziridine) was added to obtain an adhesive composition solution of ADH1 (hereinafter sometimes referred to as an “adhesive solution”). Further, an adhesive solution of ADH2 was obtained in the same manner as in the case of the polyurethane except that the crystalline polycaprolactone solution was used instead of the crystalline polyurethane solution.
The adhesive solutions of ADH1 and ADH2 were both transparent.

[0070] 5. Preparation of Adhesive Sheet Each adhesive solution was applied on the release surface of the liner shown in Table 1, dried at 90 ° C. for 5 minutes, and placed on the liner.
An adhesive layer made of each adhesive composition having a thickness of 30 μm was formed. A base made of a vinyl chloride homopolymer film having a thickness of 50 μm was dry-laminated on the adhesive layer to obtain an adhesive sheet of each example. In each case, the base material was common, but the combination of the adhesive composition and the liner was
As shown in Table 1, each was different.

The liner (release paper) used in each example
Will be described in detail. Release paper 1: A paper liner having a thickness of 120 μm, in which an undercoat made of a clay coat is laminated on both sides of the paper, and a silicone release coat is laminated on the undercoat.
Ra of the peeled surface was 1.2 μm. Release paper 2: A paper liner having a thickness of 140 μm, in which an undercoat made of polyethylene is laminated on both sides of the paper, and a silicone release coat is laminated on the undercoat.
Ra of the peeled surface was 0.7 μm. Release paper 3: A paper liner having a thickness of 180 μm, in which an undercoat made of polyethylene is laminated on both sides of the paper, and a silicone release coat is laminated on the undercoat.
On the peeling surface, convex portions composed of a plurality of ridges corresponding to the grooves to be transferred to the adhesive layer were arranged continuously along a cross-cut line so as to cross each other. The height of the protrusion was 19.5 μm (the maximum depth of the bonding surface was 19.5 μm). The maximum distance between the adjacent ridges (distance between the bottom surfaces of the ridges) was 1.2 mm, and the width of the ridge was 55 μm. Further, the vertical cross-sectional shape of the ridge was substantially trapezoidal, and correspondingly, the groove of the adhesive layer had a substantially trapezoidal vertical cross-sectional shape. Release paper 4: A paper liner having a thickness of 180 μm, in which an undercoat made of polyethylene is laminated on both sides of the paper, and a silicone release coat is laminated on the undercoat.
Truncated cone-shaped depressions were regularly arranged on the peeling surface.
Depth of truncated cone = 15 μm, diameter of opening on peeling surface =
50 μm, arrangement pitch of depressions = 300 μm. Release paper 5: In the release paper 4, a plurality of glass microspheres (5 to 20 μm in diameter) were arranged at the bottom of the depression and used.

6 Measurement of area contact ratio The area contact ratio was measured using the adhesive sheet of each example according to the method described above. As a glass slide, Mats
EXCEL TVIP manufactured by Nippon Avionics Co., Ltd. was used as an image processing device using S-1111 manufactured by unami Co., Ltd.
-4100 was used. Table 1 shows the measurement results. In each case, the area contact ratio was measured for both the case where pressure bonding was performed at room temperature (about 25 ° C.) as it was (only compression bonding) and the case where bonding was performed at room temperature (about 25 ° C.) after heating treatment (heating treatment). . The heat treatment conditions were as follows. The adhesive sheet with the liner attached is placed in an 85 ° C oven for 1 hour.
After heating for 5 minutes, the mixture was cooled at room temperature (about 25 ° C.) for 5 minutes.
After cooling, the liner was removed, and the sample was pressed against a slide glass to prepare a measurement sample.

[0074] 7. When the adhesive sheet is lightly bonded (temporarily bonded) to the adherend surface of the adherend, a passage (communication passage) communicating with the outside is formed between the adhesive surface of the adhesive layer and the adherend surface. In this case, the air (bubbles) trapped between the adhesive surface and the adhered surface can be easily released to the outside. On the other hand, as described above, in order to effectively prevent moisture or the like from intruding from the outside between the adhesive surface and the adherend surface, such an adhesive sheet is pressed after the adhesive position of the adhesive sheet is determined. It is preferable to close the communication passage.

Therefore, the unevenness of the adhesive surface was easily deformed by heat treatment, and it was evaluated as follows whether or not such a communication path could be closed by pressure bonding. At both room temperature (approximately 25 ° C.) crimping only (crimping only) and after heat treatment, crimping (heating treatment), the adhesive sheet is placed on the slide glass in the same manner as in the case of measuring the area contact ratio. Crimped. The heat treatment conditions were the same as those for the area contact ratio described above. After the adhesive sheet was pressed, the presence or absence of the communication path was visually observed from the side opposite to the adhesive sheet adhesive surface of the slide glass. When the communication path was not closed and remained in communication with the outside, it was determined as “present”, and when the communication path was closed, it was determined as “absent”. Table 1 shows the evaluation results.

[0082] 8. In an environment of slidability of 23 ° C., the liner was removed from the adhesive sheet, and the adhesive surface was placed on the melamine-baked painted plate with the adhesive surface facing the painted plate surface. As a criterion for evaluation, Comparative Example 1 (the adhesive surface was smooth,
The case where the area contact ratio was equal to or less than 100%) was determined as “Even”, and the case where the horizontal movement was smoother than Comparative Example 1 was determined as “Good”. The adhesive sheet evaluated was not subjected to heat treatment.

9. Adhesive force (peeling strength) Under an environment of 20 ° C., the liner was removed from the adhesive sheet, and the sheet was adhered to a melamine-baked coated plate manufactured by NTP Co., Ltd. as an adherend. Pasting operation is JIS Z 0237
According to 8.2.3, the adhesive sheet and the adherend were pressure-bonded. After being left at the same temperature for 48 hours, the 180-degree peel strength was measured with Tensilon. This was defined as the initial peel strength (In). On the other hand, the adhesive sheet pressed on the adherend in the same manner as above was heated to about 100 ° C. with an industrial drier, left at room temperature (about 25 ° C.) for 5 minutes, and immediately after cooling, a peel test was performed in the same manner as above. The peel strength was determined as the thermal peel strength (P). Further, after the heat treatment under the same conditions as in the case of the above-mentioned area contact ratio, it was pressure-bonded to the adherend, and the initial peel strength and the thermal peel strength were measured in the same manner as above. Table 2 shows the results.

10. Peeling cleanability (paste residue and peeling residue
Confirmation) Observation of the adhered surface after the above-mentioned peel strength measurement shows that no adhesive (polymer component of the adhesive) or residue (stain) is observed, and that even a slight amount of adhesive or residue is observed. If so, it was determined to be defective. The adhesive sheets of Examples 1 to 8 are all
The peel cleanability was determined to be good.

(Comparative Example 1) A liner was a PET liner manufactured by Tosero Co., Ltd., product number SP-PETA-01-75-
An adhesive sheet of this example was obtained in the same manner as in Example 1 except that BU (release paper 6) was used. The release surface of the liner used in this example was very smooth, and Ra was less than 0.1 μm. Tables 1 and 2 show the results of each measurement and evaluation in the same manner as in the examples.

(Comparative Example 2) The same procedure as in Example 2 was carried out except that the adhesive polymer was replaced with an adhesive polymer (PSA3) obtained by polymerizing a mixed monomer having the following composition, and no crystalline polymer was used. Thus, an adhesive sheet of this example was obtained.
The mixed monomer contained 70 parts by mass of isooctyl acrylate, 23 parts by mass of methyl acrylate, and 7 parts by mass of acrylic acid. Tables 1 and 2 show the results of each measurement and evaluation in the same manner as in the examples.

Comparative Example 3 The adhesive polymer was changed to an adhesive polymer (PSA4) obtained by polymerizing a mixed monomer having the following composition, and no crystalline polymer was used, and the amount of the crosslinking agent was changed. Except for the above, an adhesive sheet of this example was obtained in the same manner as in Example 1. The mixed monomer contained 90 parts by mass of 2-methylbutyl acrylate and 10 parts by mass of acrylic acid. The amount of the crosslinking agent was 0.14 parts by mass based on 100 parts by mass of the adhesive polymer. Tables 1 and 2 show the results of each measurement and evaluation in the same manner as in the examples.

(Comparative Example 4) The adhesive polymer was changed to an adhesive polymer (PSA5) obtained by polymerizing a mixed monomer having the following composition, and a tackifier was added without using a crystalline polymer, and Example 6 except that the amount of the crosslinking agent was changed
In the same manner as in the above, an adhesive sheet of this example was obtained. The mixed monomer contained 93 parts by mass of isooctyl acrylate and 7 parts by mass of acrylic acid. The amount of the tackifier was 16 parts by mass based on 100 parts by mass of the adhesive polymer. The amount of the crosslinking agent was 0.05 part by mass with respect to 100 parts by mass of the adhesive polymer. The results of each measurement and evaluation (excluding the adhesive strength) are shown in Table 1 in the same manner as in the examples.

(Comparative Example 5) An adhesive sheet of this example was obtained in the same manner as in Example 8, except that the same adhesive layer as that used in Comparative Example 4 was used. Tables 1 and 2 show the results of each measurement and evaluation in the same manner as in the examples. In the adhesive sheet of the present example, a plurality of glass beads were embedded in the convex portion of the adhesive surface. Therefore, the slidability was good. However, the thermal peeling easiness was not exhibited, and the thermal peeling strength was higher than that of Example 8, and the value was almost the same as the initial peeling strength.

[0083]

[Table 1]

[0084]

[Table 2]

Continued on the front page F-term (reference) 4J004 AA02 AA05 AA07 AA10 AA11 AA14 AA15 AB01 AB05 AB07 CA03 CA04 CA05 CA06 CA08 CB02 CE02 DA02 DA04 DB02 DB04 DB05 FA01 FA05 FA09 GA01 GA02 4J040 CA061 DB051 DF011 DF041 EF071 DF011 EF071 EF291 EF301 EF311 EF321 EK031 EL021 GA05 GA07 GA08 GA11 JA09 JB09 LA01 MA02 MA04 MA05 MA10 NA02 NA12 NA19 PA42

Claims (4)

[Claims] 1. A bonding method comprising: a base material; and an adhesive layer disposed on at least one main surface of the base material, wherein the adhesive layer includes a crystalline polymer and a crosslinked adhesive polymer. An adhesive sheet comprising an adhesive composition and having irregularities composed of the adhesive composition on the surface of the adhesive layer, wherein the crystalline polymer has a polyol unit formed from a crystalline polyol as a repeating unit in the molecule. The adhesive sheet, wherein the adhesive polymer is compatible with the crystalline polymer at a temperature higher than the melting point of the crystalline polymer. 2. The adhesive sheet according to claim 1, wherein the crystalline polyol is polycaprolactone. 3. The adhesive sheet according to claim 1, wherein the adhesive polymer is a polymer having a hydroxyl group, a phenyl group, and an alkyl group having 4 to 10 carbon atoms in a molecule. 4. A substrate comprising: a base material; an adhesive layer disposed on at least one main surface of the base material; and a liner having a release surface in contact with the adhesive surface of the adhesive layer. Having irregularities provided on the surface,
The surface of the adhesive layer is provided with irregularities on which the irregularities of the liner release surface are transferred, and the adhesive layer is formed of a crystalline polymer and an adhesive composition including a crosslinked adhesive polymer. The adhesive sheet having irregularities made of the adhesive composition on the surface of the adhesive layer, wherein the crystalline polymer has a polyol unit formed from a crystalline polyol as a repeating unit in a molecule thereof, and The adhesive sheet, wherein the crystalline polymer is compatible with the crystalline polymer at a temperature higher than the melting point of the crystalline polymer.