JP6407535B2 - Adhesive sheet and method for producing adherend laminate - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer whose contact surface with an adherend changes before and after heating is disposed between a first separator and a second separator, and an adherend laminate using the pressure-sensitive adhesive sheet The present invention relates to a method for manufacturing a product.

  A double-sided adhesive that can bond an object (first adherend) and an object (second adherend) with an appropriate adhesive force, and can be easily peeled off after the purpose of use is no longer required As a layer, a “material having a base material” (Patent Document 1) provided with an adhesive layer on both the front and back surfaces of the base material, and a “base material-less material” having no base material composed entirely of an adhesive layer. (Patent Document 2) is known. Moreover, what was formed as an adhesive layer of this kind by the adhesive composition containing a thermally expansible microsphere as a thermal foaming agent is known (patent document 3). In any form, such a double-sided adhesive layer is often provided in the form of an adhesive sheet disposed between the first separator and the second separator. Used when

JP 2003-238915 A JP 2006-342223 A JP 2006-257372 A

This type of pressure-sensitive adhesive sheet having a first separator / double-sided pressure-sensitive adhesive layer / second separator structure is usually subjected to position correction after peeling off the first separator to expose the pressure-sensitive adhesive layer and sticking it to the adherend. Therefore, there is an increasing demand for performance (reworkability) that can be pasted again after being peeled from the adherend.
However, since the pressure-sensitive adhesive sheet having the above structure is used after peeling off the first separator and sticking it to the adherend, the second separator is peeled off after sticking to the adherend. Without peeling off the part consisting of the adhesive layer and the second separator from the adherend, it is not easy. On the other hand, when a pressure-sensitive adhesive designed to have a low adhesive force for improving reworkability is used in the pressure-sensitive adhesive layer, there arises a problem that the adhesiveness when bonded to the adherend becomes insufficient. In addition, when the second separator is peeled off after being attached to the adherend, the entire portion composed of the adhesive layer and the second separator is easily peeled off, and it is difficult to peel only the second separator. occured.

  Note that the pressure-sensitive adhesive sheet disclosed in Patent Document 3 reduces the contact area with the adherend by generating irregularities at the interface between the adherend and the adhesive layer when heated. As compared with other types of pressure-sensitive adhesive sheets, the adherend can be easily peeled off. However, when heating and generating unevenness at the interface between the adherend and the adhesive layer to reduce the contact area with the adherend and peeling the adherend, the unevenness height and density of the adhesive layer surface layer It is difficult to control uniformly. For this reason, in the part where there are few convex parts and there are many concave parts, or in the part where the height of the convex part is non-uniform, the reduction in the contact area is insufficient, which may cause partial adhesion. Therefore, there is a demand for suppressing a decrease in work efficiency and processing accuracy without preventing uniform peeling over the entire adherend surface and without causing contamination due to adhesive residue.

  An object of the present invention is to provide a pressure-sensitive adhesive sheet having good reworkability and excellent adhesion after reworking, and a method for producing an adherend laminate using this pressure-sensitive adhesive sheet.

In the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer in which the pressure-sensitive adhesive force of the contact surface with the adherend changes before and after heating is arranged between the first separator and the second separator, the pressure-sensitive adhesive layer includes By forming a pressure-sensitive adhesive composition further containing a tackifier resin having a large molecular weight together with fine particles, and adjusting the surface roughness of one surface of the pressure-sensitive adhesive layer to a predetermined range, the reworkability is good and after reworking The present inventors have found that the adhesiveness can be excellent and have completed the present invention.
In addition, by using a thermal foaming agent as the fine particles, in addition to the above performance, even when the adherend laminate finishes its intended purpose and the joining of the first adherend and the second adherend becomes unnecessary. It has also been found that the adherend can be uniformly peeled without causing contamination due to adhesive residue or the like and partial adhesion on the entire adherend surface.

  That is, according to the present invention, there are provided a pressure-sensitive adhesive sheet having the following configuration and a method for producing an adherend laminate using the pressure-sensitive adhesive sheet. Furthermore, the processing method of the adherend laminated body shown below is also provided.

In the pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive layer in which the adhesive force of the contact surface with the adherend changes before and after heating is disposed between the first separator and the second separator, and the pressure-sensitive adhesive layer is (A). It is formed of a pressure-sensitive adhesive composition containing at least a pressure-sensitive adhesive, fine particles, and a tackifying resin having a weight average molecular weight of 800 or more, and (B) the surface roughness of one surface is 0.01 μm or more and 0.3 μm or less. It is characterized by being adjusted.

In the pressure-sensitive adhesive sheet of the present invention, when the first separator is peeled off under condition 1 to obtain the first pressure-sensitive adhesive sheet with the pressure-sensitive adhesive layer exposed on the second separator, the peeling force of the first separator is a.
The first pressure-sensitive adhesive sheet is obtained by stacking the first pressure-sensitive adhesive sheet on the first adherend with the pressure-sensitive adhesive layer facing each other to obtain the first laminate, and then peeling the first pressure-sensitive adhesive sheet from condition 1 on the first laminate. The peel force of the sheet is a1,
The first laminate is heated under conditions 3 while being heated to press one side to obtain a second laminate, and then the first adhesive sheet is peeled from the second laminate in an environment of 25 ° C. When the peel strength of the first pressure-sensitive adhesive sheet is a2,
The peeling force of the second separator when the second separator was peeled from the second laminate in an environment of 25 ° C. to obtain the second ′ pressure-sensitive adhesive sheet with the pressure-sensitive adhesive layer exposed on the first adherend was expressed as b. age,
After the 2 ′ adhesive sheet is placed on the second adherend with the adhesive layer facing each other to obtain a 3 ′ laminate, the 2 ′ adhesive sheet is peeled from the 3 ′ laminate in an environment of 25 ° C. When the peeling force of the second ′ adhesive sheet is b1,
The peel strength of the adhesive layer is 0.01 to 0.45 (N / 25 mm) for a, a1 and b, 0.1 to 1.50 (N / 25 mm) for a2 and b1, preferably 0.25 to It is preferable that 1.50 (N / 25 mm) and the relationship A (that is, a <a1 ≦ b <a2 ≦ b1) is satisfied.

Condition 1: The peeling environment is 25 ° C., the peeling direction is a direction of 180 degrees opposite to the direction in which one end of the first separator faces, the peeling speed is 300 mm / min, and the peeling width is 25 mm.
Condition 2: The peeling environment is 25 ° C., and the time from the first laminate to the start of peeling is within 1 minute.
Condition 3: The applied temperature is 40 ° C. or higher and 180 ° C. or lower, the applied pressure is 0.2 to 1.5 MPa, and the time is 1 to 60 seconds.

  In the pressure-sensitive adhesive sheet of the present invention, a thermal foaming agent can be used as fine particles contained in the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer.

When the thermal foaming agent is used for the fine particles, the pressure-sensitive adhesive sheet of the present invention (sometimes referred to as a specific pressure-sensitive adhesive sheet) includes the peeling force a, a1, a2, b and b1 before heating of the pressure-sensitive adhesive layer. When the 3 ′ laminate is subjected to the heat treatment under the condition 4 to obtain the third “laminate”, the bonding force between the second “adhesive sheet of the third” laminate and the second adherend is b2. ,
When the bonding force between the third adhesive sheet with the adhesive layer exposed on the second adherend of the third ”laminate and the first adherend is a3,
It is preferable that the peeling force before heating of the adhesive layer and the bonding strength after heating further satisfy the relationship A1 (that is, a3≈b2 <a).

Condition 4: The heating temperature is 10 ° C. or more higher than the temperature of the heating treatment in Condition 3, and the heating time is 15 minutes or more.

In the method for producing an adherend laminate of the present invention, the first pressure-sensitive adhesive sheet is obtained by pulling the first separator away from the pressure-sensitive adhesive sheet having the above-described configuration to expose the pressure-sensitive adhesive layer on the second separator. And a first step of obtaining a first laminate by overlapping the first adhesive body with the adhesive layer facing each other,
After separating the first pressure-sensitive adhesive sheet from the first laminate and changing the stacking position with the first adherend, the first adhesive sheet is again piled on the first adherend to obtain a first ′ laminate;
A second step of obtaining a second laminate by subjecting the first 'laminate to a heating treatment of pressing one side while heating at 40 ° C or higher and 180 ° C or lower;
The second separator is separated from the second laminate to obtain a second pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer exposed on the first adherend, and then the second pressure-sensitive adhesive layer is opposed to the second pressure-sensitive adhesive layer. And a third step of obtaining an adherend laminate by the third laminate.

  The processing method of the adherend laminate of the present invention is the method described above for the adherend laminate by the third laminate produced by the above method using the specific pressure-sensitive adhesive sheet of the present invention using a thermal foaming agent for fine particles. The heat treatment is performed at a temperature higher by 10 ° C. or more than the temperature of the heat treatment performed in the second step. By performing such heat treatment, the adherend laminate produced by the above method can cleanly separate the first adherend, the adhesive layer, and the second adherend.

  In the pressure-sensitive adhesive sheet of the present invention, in a mode in which the pressure-sensitive adhesive layer is disposed between the first separator and the second separator, the pressure-sensitive adhesive layer is formed of the pressure-sensitive adhesive composition, and the surface characteristics of one surface of the pressure-sensitive adhesive layer are Appropriate adjustment (surface roughness 0.01 μm or more and 0.3 μm or less) provides good reworkability and excellent adhesion after reworking, and is expected to improve workability and productivity. Is done.

  The pressure-sensitive adhesive sheet of the present invention uses the thermal foaming agent as the fine particles to be contained in the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer, so that the above-described reworkability is good and the adhesiveness after reworking is also excellent. In addition, when the adherend laminate finishes its intended purpose and the joining of the first adherend and the second adherend is no longer necessary, the adherend is contaminated with adhesive residue or the entire adherend surface. It can be made to peel uniformly from the adherend without causing partial adhesion.

  According to the production method of the present invention, since the pressure-sensitive adhesive sheet of the present invention having good reworkability is used, it can be re-applied to the adherend any number of times, and a predetermined heating is applied to the laminate after correct positioning. By performing the treatment, it is possible to develop a good adhesion holding force (adhesion with the adherend) to the adherend. Therefore, an adherend laminate in which the adherend does not fall off can be efficiently produced.

  According to the treatment method of the present invention, when the adherend laminate obtained by the production method of the present invention has finished its intended purpose and the joining with the adherend is no longer necessary, by applying a predetermined heat treatment , Tack with the adhesive layer is appropriately reduced. Accordingly, the adherend can be uniformly peeled from the adhesive layer without causing contamination due to adhesive residue or the like due to the adhesive layer. The adherend that is uniformly peeled without causing contamination due to adhesive residue or the like can be used for the next use.

FIG. 1 is a cross-sectional view showing an example of the pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a cross-sectional view of the first pressure-sensitive adhesive sheet prepared in the first step according to an example of the method of the present invention. FIG. 3 is a cross-sectional view of the first laminate prepared in the first step. FIG. 4 is a cross-sectional view of the second laminate prepared in the second step. FIG. 5 is a cross-sectional view of the second adhesive sheet prepared in the third step. FIG. 5A is a cross-sectional view of a second 'adhesive sheet prepared for confirmation of peel force. FIG. 6 is a cross-sectional view of an adherend laminate formed by the third laminate obtained in the third step. FIG. 6A is a cross-sectional view of the 3′-stacked body prepared for checking the peeling force. FIG. 7 is a cross-sectional view showing a state of heat treatment applied to the third laminate of FIG. 6 in the fourth step. FIG. 7A is a cross-sectional view of a third ”laminate prepared for confirmation of bonding strength. FIG. 8 is a sectional view showing a state of separation of the first adherend, the adhesive layer and the second adherend obtained in the fourth step.

  The pressure-sensitive adhesive sheet of the present invention will be described. An adhesive sheet 1 according to an example of the present invention is configured by disposing an adhesive layer 3 between a first separator 5 and a second separator 7 as shown in FIG.

  The first separator 5 and the second separator 7 are not particularly limited. For example, polyethylene laminated paper, polypropylene, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, triacetyl cellulose, polyvinyl chloride, acrylic, A plastic film such as polystyrene, polyamide, polyimide, vinylidene chloride-vinyl chloride copolymer, or the like obtained by subjecting one surface of the plastic film to a mold release treatment can be used. However, the first separator 5 should have a lighter peeling force when peeling from the adhesive layer 3 than the second separator 7.

  The thicknesses of the first separator 5 and the second separator 7 are not particularly limited, but are generally 10 μm to 250 μm, preferably 25 μm to 125 μm. The first separator 5 has a lighter peeling force than the second separator 7. From the viewpoint of achieving this, it is preferable to make the thickness of the first separator 5 thinner than the thickness of the second separator 7.

The adhesive layer 3 only needs to change the adhesive force of the contact surface with the adherend before and after heating. Therefore, the adhesive layer 3 may be in the form of “baseless” (baseless) formed only by the adhesive layer, Or the aspect of the "base material ed" (base material do) in which the adhesion layer is formed in both the front and back of a base material may be sufficient. Examples of the adherend include a first adherend and a second adherend described later. As the base material used in the case of the base material, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, cellophane, diacetyl cellulose, triacetyl cellulose, acetyl cellulose butyrate, polyvinyl chloride, polyvinylidene chloride, Polyvinyl alcohol, ethylene-vinyl acetate copolymer, polystyrene, polycarbonate, polymethylpentene, polysulfone, polyether ether ketone, polyether sulfone, polyether imide, polyimide, fluorine resin, nylon, acrylic, cycloolefin, norbornene compound, etc. And those having a thickness of about 5 μm to 175 μm are used.
Below, the case where the adhesion layer 3 is a base material-less aspect is illustrated and demonstrated.

About (A) The pressure-sensitive adhesive layer 3 of this example is formed of a pressure-sensitive adhesive composition containing fine particles, a pressure-sensitive adhesive, and a tackifying resin as essential components (A).

  Fine particles include inorganic pigments (eg kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, satin white, zinc carbonate, magnesium carbonate, aluminum silicate, calcium silicate, magnesium silicate, silica, calcium carbonate, colloidal silica. Colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrohalosite, magnesium hydroxide, etc.), organic pigments (eg acrylic plastic pigment, styrene plastic pigment, urea resin, melamine resin, etc.) These can be used alone or in combination. Moreover, the thermal foaming agent mentioned later can also be used as fine particles.

  The size of the fine particles may be appropriately selected depending on the use of the sheet 1 of the pressure-sensitive adhesive layer and varies depending on the thickness of the pressure-sensitive adhesive layer. However, it cannot be generally stated, but usually the mass average particle size is preferably 5 to 20 μm. . If the size of the fine particles to be used is too small or too large, it may be difficult to control the surface roughness of the adhesive layer 3, and as a result, the adhesiveness and peelability are not stable, and the adherend laminate There may be inconveniences in the manufacturing process. When the size of the fine particles is too small with respect to the thickness of the pressure-sensitive adhesive layer, the convex portions are not sufficiently formed on the pressure-sensitive adhesive layer 3, and the peelability (reworkability) from the adherend before heating treatment is insufficient. Since it may become, it is not preferable. Also, if the thickness of the adhesive layer is too large, the surface of the adhesive layer 3 may be formed with larger irregularities than necessary, so that the adhesion with the adherend after heating is reduced. This is not preferable.

  What is necessary is just to select suitably the mixture ratio of microparticles | fine-particles so that the unevenness | corrugation of the adhesion layer 3 surface can be formed so that rework property may be obtained, Usually, it is the range of 5-50 mass parts with respect to 100 mass parts of adhesives mentioned later. . In the experiment, when the blending ratio of the fine particles is less than 5 parts by mass, the convex part of the surface layer of the adhesive layer 3 tends to be less likely to obtain reworkability, and when it exceeds 50 parts by mass, the surface of the adhesive layer 3 is more than necessary. Since there is a possibility that irregularities may be formed on the surface, in this case, the adhesion with the adherend after the heating treatment tends to be lowered, which is not preferable. A preferable blending ratio is 8 to 40 parts by mass, more preferably 10 to 30 parts by mass from the viewpoint of peelability (reworkability) from the adherend before heating treatment and adhesion between the adherend after heating treatment. It is.

  A thermal foaming agent can also be used as the fine particles. When a thermal foaming agent is used, the adherend laminate ends its intended purpose, and even when the first adherend 12 (described later) and the second adherend 14 (described later) are not required to be joined, the adherend is required. In addition, the effect of being able to peel evenly without causing contamination due to adhesive residue or the like and partial adhesion on the entire adherend surface is added to the effect of this example (reworkability, which will be described later).

The thermal foaming agent is not particularly limited, and for example, a known thermal foaming agent (such as a thermal decomposition type, expanded graphite, or microencapsulated one) can be appropriately selected and used. An encapsulated product (hereinafter referred to as “thermally expandable microsphere”) can be preferably used.
As a heat-expandable microsphere, a microsphere having a structure in which a foaming agent is enclosed inside an elastic outer shell and exhibiting a heat expandability (a property that the whole expands when heated) is given as a preferable example. Can do. Examples of the outer shell having elasticity include a hot-melt material and a material that breaks due to thermal expansion, such as vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, etc. What was formed in (1) can be mentioned as a suitable example. Examples of the foaming agent include substances such as hydrocarbons such as isobutane, propane, and pentane that are easily gasified by heating and expand. Commercially-available products of thermally expandable microspheres include, for example, the trade name “Matsumoto Microsphere” series (Matsumoto Yushi Seiyaku Co., Ltd.), Advancel EM series (Sekisui Chemical Co., Ltd.), Expansel (Nihon Ferrite Co., Ltd.) And the like.

  The size of the heat-expandable microspheres may be appropriately selected within the range of the above-described fine particle size in consideration of the thickness of the adhesive layer, and specifically, the mass average particle size is 10 to 20 μm. It is preferable. In addition, when the size of the heat-expandable microsphere to be used is too small with respect to the thickness of the pressure-sensitive adhesive layer, the protrusion is not sufficiently formed on the pressure-sensitive adhesive layer 3 after the heat treatment, and the adherend is peeled off This is not preferable because it tends to be difficult to peel off or tends to leave adhesive residue. In addition, when the thickness is too large for the pressure-sensitive adhesive layer, unevenness may be formed on the surface of the pressure-sensitive adhesive layer 3 before the heat treatment, so that the adhesion with the adherend before the heat treatment tends to decrease. This is not preferable.

  Thermally expandable microspheres can be used after adjusting their particle size distribution. The particle size distribution may be adjusted by classifying and removing particles having a relatively large particle size contained in the heat-expandable microspheres to be used with a centrifugal air classifier, dry classifier, sieving machine, or the like. By removing particles having a larger particle size than the average particle size and sharpening the particle size distribution, the surface shape after the heat treatment can be made uniform. Specifically, the standard deviation of the particle size distribution of the heat-expandable microspheres is desirably 5.0 μm or less, preferably 4.5 μm or less, and more preferably 4.0 μm or less. When the standard deviation is larger than 5.0 μm, the height difference of the surface layer of the pressure-sensitive adhesive layer 3 after the heat treatment becomes large, and accordingly, a surface shape with uneven unevenness density is formed. As a result, it becomes difficult to obtain uniform peeling.

  The expansion ratio of the thermally expandable microspheres is preferably 3 times or more, and more preferably 5 times or more. On the other hand, it is preferably 15 times or less, and more preferably 12 times or less. When the expansion ratio of the thermally expandable microspheres that can be used is preferably in the range of 3 to 15 times, the adhesive force of the adhesive layer 3 can be efficiently reduced by heat treatment. The outer shell of the thermally expandable microsphere preferably has an appropriate strength that does not rupture even when the thermally expandable microsphere expands to the predetermined expansion ratio.

Examples of other thermal foaming agents include pyrolytic foaming agents and expanded graphite. Pyrolytic foaming agents are classified into inorganic and organic types.
Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, azides and the like. Examples of the organic foaming agent include water, fluorinated alkanes (for example, trichloromonofluoromethane, dichloromonofluoromethane, etc.), azo compounds (for example, azobisisobutyronitrile, azodicarbonamide (ADCA), Barium azodicarboxylate, etc.), hydrazine compounds (for example, paratoluenesulfonyl hydrazide, diphenylsulfone-3,3′-disulfonylhydrazide, 4,4′-oxybis (benzenesulfonylhydrazide), allylbis (sulfonylhydrazide), etc.) , Semicarbazide compounds (eg, ρ-toluylenesulfonyl semicarbazide, 4,4′-oxybis (benzenesulfonyl semicarbazide), etc.), triazole compounds (eg, 5-morpholyl-1,2,3,4-thiatriazol) Etc.), N- nitroso compounds (e.g., N, N'-dinitrosopentamethylenetetramine, N, N'-dimethyl -N, N'-dinitrosoterephthalamide, etc.), and the like.
These thermal foaming agents can be used alone or in combination.

  In the case of using a thermal foaming agent, the blending ratio thereof may be appropriately selected and selected so that the unevenness on the surface of the pressure-sensitive adhesive layer 3 after the heat treatment can be sufficiently formed within the above-described blending ratio of the fine particles. Pressure sensitive adhesive to be described later: 10 to 50 parts by mass with respect to 100 parts by mass. In the experiment, if the blending ratio of the thermal foaming agent is less than 10 parts by mass, the convex part of the surface layer of the adhesive layer after the heat treatment tends to be less likely to be peeled off, and if it exceeds 50 parts by mass, it is heated more than necessary. Since unevenness may be formed on the surface of the pressure-sensitive adhesive layer 3 before the treatment, in this case, the adhesion with the adherend before the heat treatment tends to be lowered, which is not preferable. From the viewpoints of adhesion to the adherend before the heat treatment and releasability from the adherend after the heat treatment, a preferable blending ratio is 13 to 40 parts by mass, and more preferably 15 to 30 parts by mass.

The thermal foaming temperature of the thermal foaming agent may be appropriately selected in consideration of the use temperature of the pressure-sensitive adhesive sheet 1, and preferably the one having a temperature higher by 10 ° C. than the heating treatment temperature described later is used. Is desirable.
The thermal foaming temperature corresponds to the thermal expansion temperature when using thermally expandable microspheres as the thermal foaming agent, and corresponds to the thermal decomposition temperature when using a pyrolytic foaming agent. Here, the “thermal expansion temperature” is synonymous with the foaming start temperature, and in this example means the thermal expansion start temperature in the TMA measurement, and does not mean the maximum expansion temperature at which the volume expands to the maximum.

  What is necessary is just to select suitably as an adhesive from the adhesives conventionally used when forming the adhesion layer which contained microparticles | fine-particles. However, it is preferable to use an acrylic pressure-sensitive adhesive in terms of the uneven shape formed on the surface of the pressure-sensitive adhesive layer 3, the initial pressure-sensitive adhesive force, and the removability. There is no restriction | limiting in particular in the composition of an acrylic adhesive.

  The weight average molecular weight of the acrylic pressure-sensitive adhesive is not particularly limited, but is preferably 10,000 to 2,000,000, more preferably 100,000 to 1,500,000, and 200,000 to 1,000,000. Is particularly preferred. By making the weight average molecular weight of the acrylic pressure-sensitive adhesive within the above range, the adhesiveness with the adherend after the heating treatment is improved, and the adhesive remains on the adherend when the heat treatment is performed. It can be made easy to peel without.

  The acrylic pressure-sensitive adhesive is preferably one that can react with the crosslinking agent. The acrylic pressure-sensitive adhesive includes a copolymer of an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester and a monomer having a functional group capable of reacting with a crosslinking agent. Examples of the "alkyl ester" of acrylic acid alkyl ester and methacrylic acid alkyl ester include, for example, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester. Hexyl ester, heptyl ester, octyl ester, isooctyl ester, 2-ethylhexyl ester, isodecyl ester, dodecyl ester, tridecyl ester, pentadecyl ester, octadecyl ester, nonadecyl ester, eicosyl ester, etc. . Examples of the functional group capable of reacting with the crosslinking agent include a carboxyl group and a hydroxyl group.

  Examples of the monomer whose functional group capable of reacting with the crosslinking agent is a carboxyl group include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. . Moreover, as a monomer whose functional group is a hydroxyl group, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxyhexyl acrylate, Examples include hydroxyhexyl methacrylate, hydroxyoctyl acrylate, hydroxyoctyl methacrylate, hydroxydecyl acrylate, hydroxydecyl methacrylate, hydroxylauryl acrylate, and hydroxylauryl methacrylate.

  Monomers having a functional group capable of reacting with a crosslinking agent can be used alone or in combination of two or more. The ratio between the (meth) acrylic acid alkyl ester and the monomer having a functional group capable of reacting with the crosslinking agent is preferably in the range of 92: 8 to 98: 2 in terms of mass ratio. If the blending ratio of the monomer having a functional group capable of reacting with the crosslinking agent is less than this range, the peelability between the adherend and the adhesive layer 3 tends to be impaired when the thermal foaming agent is foamed. is there. On the other hand, when there are more compounding ratios of the monomer which has a functional group which can react with a crosslinking agent than this range, it exists in the tendency for the adhesive force of a to-be-adhered body and the adhesion layer 3 to become scarce. From the viewpoint of improving the adhesiveness and peelability between the adherend and the adhesive layer, the ratio of the (meth) acrylic acid alkyl ester and the monomer having a functional group capable of reacting with the crosslinking agent is a mass ratio. And more preferably 95: 5 to 93: 7.

  If desired, other monomers other than the (meth) acrylic acid alkyl ester and the monomer having a functional group capable of reacting with the crosslinking agent may be used in combination. Examples of other monomers include styrene, vinyl acetate, acrylonitrile, acrylamide, polyethylene glycol acrylate, N-vinyl pyrrolidone, and tetrafurfuryl acrylate.

  The acrylic pressure-sensitive adhesive can be obtained by radical copolymerization of monomer components. The copolymerization method in this case is conventionally known, and examples thereof include an emulsion polymerization method, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method. Moreover, it is preferable that the glass transition temperature of an acrylic adhesive is -70--20 degreeC. When the glass transition temperature is higher than −20 ° C., the adhesive force between the adherend and the adhesive layer 3 tends to decrease. On the other hand, when the glass transition temperature is less than −70 ° C., adhesive residue tends to be generated at the time of peeling after the heat treatment, and the peelability tends to be difficult. From the viewpoint of improving the adhesiveness and peelability between the adherend and the adhesive layer 3, the glass transition temperature of the acrylic adhesive is more preferably −50 ° C. to −25 ° C.

Next, the crosslinking agent will be described. The crosslinking agent may be appropriately selected according to the acrylic pressure-sensitive adhesive to be used, and is not particularly limited. Specific examples of the crosslinking agent include an isocyanate crosslinking agent, a metal chelate crosslinking agent, and an epoxy crosslinking agent. Among these, from the viewpoint of improving the peelability from the adherend after heating to a temperature at which the thermal foaming agent foams, and preventing adhesive residue on the adherend, an isocyanate-based crosslinking agent, an epoxy-based adhesive It is preferable to use a crosslinking agent.
As the isocyanate-based crosslinking agent, toluylene diisocyanate, 2,4-toluylene diisocyanate dimer, naphthylene-1,5-diisocyanate, o-toluylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, tris- (p-isocyanate phenyl) ) Thiophosphite, polymethylene polyphenyl isocyanate, hexamethylene diisocyanate, trimethylhexanemethylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate and the like.
Examples of the epoxy-based crosslinking agent include bisphenol-based epoxy resins (for example, bisphenol A type, bisphenol F type, bisphenol AD type), phenol novolac type epoxy resins, ethylene glycol diglycidyl ether, 1,6-hexanediol glycidyl ether, Trimethylolpropane triglycidyl ether, diglycidyl aniline, diglycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane Etc.

  From the viewpoints of adhesion to the adherend at normal temperature and releasability from the adherend after foaming of the thermal foaming agent, a polyfunctional epoxy-based cross-linking agent is preferable, and a tetrafunctional epoxy-based cross-linking agent is more preferable. Specific examples include N, N, N ′, N′-tetraglycidyl-m-xylenediamine and 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane. However, since these epoxy-based crosslinking agents tend to slow the crosslinking reaction rate, when the crosslinking reaction is insufficient, (a) a catalyst such as an amine is added to promote the crosslinking reaction. (B) It is desirable to use a monomer having an amine functional group as a constituent of the pressure-sensitive adhesive, and (c) to use an aziridine-based crosslinking agent in combination with the crosslinking agent. In particular, it is preferable to add a tertiary amine having a catalytic effect to a crosslinking agent such as N, N, N ′, N′-tetraglycidyl-m-xylenediamine.

  A crosslinking agent may be used independently or may be used in combination of 2 or more type. The blending ratio of the crosslinking agent is appropriately adjusted so that the surface roughness of the pressure-sensitive adhesive layer 3 is adjusted to a predetermined range (described later) together with fine particles (preferably a thermal foaming agent), an acrylic pressure-sensitive adhesive, and a tackifier resin having a specific molecular weight. There is no particular limitation as long as it is selected.

  Examples of the tackifying resin include xylene resins; terpene resins such as α-pinene, β-pinene, dipentene, and terpene phenol; natural rosins such as gum, wood, and tall oil; Rosin-based resins such as rosin derivatives obtained by subjecting natural rosin to hydrogenation, disproportionation, polymerization, maleation, esterification and the like; petroleum resins; coumarone-indene resins, and the like. Among them, it is essential to use those having a weight average molecular weight of 800 or more. It is desirable to use a thing of 1000 or more.

When a tackifying resin having a weight average molecular weight of 800 or more is used, the initial peeling force of the pressure-sensitive adhesive layer can be easily adjusted, and the adhesion to the adherend after the heating treatment can be further improved. . Moreover, when a thermal foaming agent is used, it becomes possible to further reduce contamination and adhesive residue on the adherend after the heat treatment.
In addition, when a xylene-based resin or a terpene phenol-based tackifying resin is used as a tackifying resin, when a thermal foaming agent is used, there is little contamination and no adhesive residue on the adherend after heat treatment. Can be more easily peeled off.

  The tackifying resin preferably has a softening point of 120 ° C. or higher. Among these, those having a softening point in the range of 120 to 170 ° C are more preferable, and those having a softening point in the range of 150 to 170 ° C are particularly preferable. When a tackifying resin having a softening point within the above range is used, the initial peeling force of the adhesive layer can be adjusted more easily, and the adhesion to the adherend after the heating treatment can be further improved. It becomes possible. Moreover, when a thermal foaming agent is used, it becomes possible to further reduce contamination and adhesive residue on the adherend after the heat treatment.

  Although the compounding ratio of tackifying resin does not have a restriction | limiting in particular, It is preferable to set it as 10-100 mass parts with respect to 100 mass parts of acrylic adhesives, Furthermore, it is preferable to set it as 15-40 mass parts. When the blending ratio of the tackifying resin is 10 parts by mass or more with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive, the peelability (reworkability) from the initial adherend is improved, and after the heating treatment The adhesion with the adherend can be further improved. However, if it exceeds 100 parts by mass, the tack may be reduced and the adhesion with the adherend after the heating treatment may be reduced. In addition, when a thermal foaming agent is used, the adherend after the heat treatment is applied. Contamination and adhesive residue may occur.

  The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer 3 is a reaction accelerator, a surfactant, a pigment, a lubricant, a colorant, an antistatic agent, as long as it does not impair the function as the pressure-sensitive adhesive composition of the present invention. Various additives such as flame retardants, antibacterial agents, antifungal agents, ultraviolet absorbers, light stabilizers, antioxidants, leveling agents, flow regulators, antifoaming agents and the like can be included.

  The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer 3 includes the above-described essential components such as fine particles (preferably a thermal foaming agent), a pressure-sensitive adhesive, a tackifier resin, and, if necessary, a crosslinking agent, a solvent, and an additive. Can be obtained in any order and dissolved or dispersed.

About (B) As mentioned above, the pressure-sensitive adhesive layer 3 is formed of a pressure-sensitive adhesive composition containing (A) a pressure-sensitive adhesive, fine particles, and a tackifier resin having a weight average molecular weight of 800 or more. The surface roughness of the surface is 0.01 μm or more, preferably 0.05 μm or more, and is adjusted to 0.3 μm or less, preferably 0.2 μm or less.

  By adjusting the surface roughness of one surface of the pressure-sensitive adhesive layer 3, the peelability (reworkability) from the initial adherend is good, and the adhesiveness to the adherend after heating is excellent In addition, when a thermal foaming agent is used, when the adherend laminate finishes its intended purpose and the joining of the first adherend and the second adherend is no longer necessary, the adhesive remains on the adherend. Uniform peeling from the adherend can be realized without causing contamination or partial adhesion on the entire adherend surface.

  In this example, the surface roughness means the arithmetic average roughness (Ra) defined in JIS B0601 on one surface (the first separator 5 side or the second separator 7 side) of the adhesive layer 3. The arithmetic average roughness (Ra) can be measured using, for example, a laser microscope (VK-9510, manufactured by Keyence Corporation).

The pressure-sensitive adhesive sheet 1 of this example shown in FIG. 1 can be obtained by applying the above-described pressure-sensitive adhesive composition between the first separator 5 and the second separator 7 and drying it as necessary.
The thickness of the pressure-sensitive adhesive layer 3 varies depending on the application of the sheet 1 of the pressure-sensitive adhesive layer and the size of the selected fine particles. For example, when a fine particle having a mass average particle diameter of 5 μm to 20 μm is used, the thickness of the adhesive layer 3 is preferably 5 μm or more, more preferably 8 μm or more as a lower limit, and 55 μm or less, further 45 μm as an upper limit. In the following, it is further preferable that the thickness is 35 μm or less. By setting the thickness of the adhesive layer 3 to 5 μm or more, it is easy to make the adhesion to the adherend after the heating treatment sufficient. By setting the thickness of the adhesive layer 3 to 55 μm or less, it is easy to make the peelability (reworkability) from the initial adherend sufficient.
Further, for example, when a thermal foaming agent having a mass average particle diameter of 10 μm to 20 μm is used as the fine particles, the thickness of the adhesive layer 3 is preferably 20 μm or more, more preferably 25 μm or more as a lower limit, and 55 μm or less as an upper limit, Further, it is preferably 45 μm or less, more preferably 35 μm or less. By making the thickness of the pressure-sensitive adhesive layer 3 20 μm or more, it is easy to make the adhesion with the adherend after the heating treatment sufficient. By setting the thickness of the pressure-sensitive adhesive layer 3 to 55 μm or less, cohesive failure hardly occurs at the time of peeling after the heat treatment, and it is easy to obtain better peelability.

  The pressure-sensitive adhesive layer 3 of this example is formed of a pressure-sensitive adhesive composition containing (A) a pressure-sensitive adhesive, fine particles, and a tackifier resin having a weight average molecular weight of 800 or more, and (B) the surface roughness of one surface is 0. It is adjusted to 0.01 μm or more and 0.3 μm or less. As a result, in the form of the pressure-sensitive adhesive sheet 1 in which the pressure-sensitive adhesive layer 3 of this example is disposed between the first separator 5 and the second separator 7, the peeling force of the pressure-sensitive adhesive layer 3 is determined by the following peeling forces a, a1, a2, When b and b1, the values of the respective peeling forces are in the following predetermined ranges, and the following relationship A is easily satisfied. When the peeling force of the pressure-sensitive adhesive layer 3 satisfies a predetermined relationship, the reworkability is further improved and the adhesiveness after reworking (adhesion with the adherend after heating treatment) is also excellent. be able to.

The peeling force a is the peeling force of the 1st separator 5 when peeling the 1st separator 5 on the conditions 1 and obtaining the 1st adhesive sheet 10 which exposed the adhesion layer 3 on the 2nd separator 7 ( (See FIG. 2).
The peeling force a1 is obtained by stacking the first pressure-sensitive adhesive sheet 10 on the first adherend 12 with the pressure-sensitive adhesive layer 3 opposed to each other to obtain the first laminated body 20, and then removing the first pressure-sensitive adhesive sheet 10 from the first laminated body 20. It is the peeling force of the 1st adhesive sheet 10 when peeling on the conditions 2 (refer FIG. 3).
The peeling force a2 was obtained by applying a heating process to press one surface while heating the first laminated body 20 under the condition 3 to obtain the second laminated body 22, and then in the environment of 25 ° C. 22 shows the peeling force of the first pressure-sensitive adhesive sheet 10 when the first pressure-sensitive adhesive sheet 10 is peeled from 22 (see FIG. 4).

The peeling force b is obtained when the second separator 7 is peeled from the second laminate 22 in an environment of 25 ° C. to obtain the second ′ pressure-sensitive adhesive sheet 11 a in which the pressure-sensitive adhesive layer 3 is exposed on the first adherend 12. Of the second separator 7 (see FIG. 5A).
The peeling force b1 was obtained by overlapping the second ′ adhesive sheet 11a with the adhesive layer 3 on the second adherend 14 to obtain the third ′ laminated body 26a, and then in the environment of 25 ° C. This is the peeling force of the second ′ pressure-sensitive adhesive sheet 11a when the second ′ pressure-sensitive adhesive sheet 11a is peeled from the body 26a (see FIG. 6A).

Condition 1 is that the peeling environment is 25 ° C., the peeling direction is a direction of 180 degrees opposite to the direction in which one end of the first separator 5 faces one end, the peeling speed is 300 mm / min, The condition is that the width is 25 mm.
Condition 2 is a condition in which the peeling environment is 25 ° C., and the time from when the first laminate 20 is obtained to the start of peeling is within one minute.
Condition 3 is a condition that the applied temperature is 40 ° C. or higher and 180 ° C. or lower, the applied pressure is 0.2 to 1.5 MPa, and the time is 1 to 60 seconds.

In this example, each value of a, a1, and b described above is preferably 0.01 to 0.45 (N / 25 mm). Each value of a2 and b1 is preferably 0.1 to 1.50 (N / 25 mm), more preferably 0.25 to 1.50 (N / 25 mm).
The relationship A is a <a1 ≦ b <a2 ≦ b1. That is, a is smaller than a1, a1 is smaller than b, b is smaller than a2, and a2 is smaller than b1.

In the form of the pressure-sensitive adhesive sheet 1 in the case where a thermal foaming agent is used as the fine particles to be included in the pressure-sensitive adhesive composition, together with the peeling force a, a1, a2, b and b1 of the pressure-sensitive adhesive layer 3 described above, When the bonding forces are set as bonding forces a3 and b2 as described below, it is preferable that the values of the peeling force and the bonding force are within the following predetermined ranges and satisfy the following relationship A1. The meaning (including conditions 1 to 3) and range of the peeling forces a, a1, a2, b, and b1 here are as described above.
Thus, in addition to the peeling force of the pressure-sensitive adhesive layer 3, the bonding force after heating of the pressure-sensitive adhesive layer 3 satisfies a predetermined relationship, so that the reworkability is good, the adhesiveness after reworking is excellent, and after the heating treatment In addition to being able to make the adherence to the adherend excellent in the case, the adherend laminate ends its intended purpose, and the joining of the first adherend 12 and the second adherend 14 becomes unnecessary. Further, it is possible to achieve uniform peeling from the adherend without causing contamination due to adhesive residue or the like and partial adhesion on the entire adherend surface.

The bonding force b2 is the same as that of the second 'adhesive sheet 11a of the third "laminate 26b and the second" when the third "laminate 26b is obtained by subjecting the third' laminate 26a to the heat treatment according to the condition 4. It is a joining force with the adherend 14 (see FIG. 7A).
The joining force a3 is a joining force between the third adhesive sheet 11b in which the adhesive layer 3 is exposed on the second adherend 14 of the third "laminate 26b and the first adherend 12 (see FIG. 7A). .

  Condition 4 is a condition that the heating temperature is 10 ° C. or more higher than the temperature of the heating treatment in Condition 3 and the heating time is 15 minutes or more.

  The relationship A1 is a3≈b2 <a. That is, a3 and b2 are substantially equal, and b2 is a relationship smaller than the minimum value a of the relationship A.

  The pressure-sensitive adhesive sheet 1 of this example has a pressure-sensitive adhesive layer 3 in which the adhesive force of the contact surface with the adherend changes before and after heating, so that it can be reattached to the adherend any number of times and heated after positioning. By performing the treatment, it can be used as an adhesive sheet having a good adhesion holding force (adhesion with the adherend) to the adherend. Further, when a thermal foaming agent is used as the fine particles, it can be used as a releasable pressure-sensitive adhesive sheet that can be easily peeled off when the purpose of use is finished and it becomes unnecessary.

  Specifically, for example, sealing parts such as envelopes and precision machine storage cases, wallpaper, labels, car bumpers, electric wires, etc., backing sheets in flexible printed circuit board (FPC) manufacturing processes, and masks in plating processes It can be widely used in the electrical / electronic industry as a temporary fixing sheet in a cutting process of a material, a semiconductor wafer, a monolithic ceramic capacitor, a display panel substrate such as a tablet PC / TV.

  Next, the manufacturing method and processing method of the adherend laminate of the present invention will be described.

(1) First, as shown in FIG. 2, the first pressure-sensitive adhesive sheet 10 is prepared by pulling the first separator 5 away from the pressure-sensitive adhesive sheet 1 and exposing the pressure-sensitive adhesive layer 3 on the second separator 7. Then, as shown in FIG. 3, the 1st adhesion sheet 10 is made to oppose the adhesion layer 3, and is piled up on the 1st to-be-adhered body 12, and the 1st laminated body 20 is prepared (1st process).
Examples of the first adherend 12 include a polyethylene terephthalate film and a polyethylene naphthalate film.

  In this example, since the pressure-sensitive adhesive sheet 1 that can be re-attached to the adherend is used for the preparation of the first laminated body 20, the overlapping position of the first pressure-sensitive adhesive sheet 10 with respect to the first adherend 12 is determined. When it is not appropriate, the first pressure-sensitive adhesive sheet 10 is pulled away from the first laminate 20. Next, after changing the overlapping position with the first adherend 12, the first adhesive sheet 10 is again overlapped with the first adherend 12 to obtain a first ′ laminate. The obtained 1 'stack is used as the first stack 20 for processing the second stack 22. The number of times the overlapping position can be changed is, for example, 10 times or more.

  In the pressure-sensitive adhesive sheet 1 of this example used for manufacturing the adherend laminate, the pressure-sensitive adhesive layer 3 is formed of the pressure-sensitive adhesive composition, and the surface characteristics (surface roughness) of one surface of the pressure-sensitive adhesive layer 3 are appropriately adjusted. As a result, the reworkability is good and the adhesiveness after reworking is also excellent.

  (2) Next, as shown in FIG. 4, the 1st laminated body 20 is heated, and the 2nd laminated body 22 is prepared (2nd process). The heating process is a process of pressing one surface of the first stacked body 20 while heating. The heating temperature (T1) is 40 ° C. or higher, preferably 50 ° C. or higher, and is 180 ° C. or lower, preferably 100 ° C. or lower. When heat-expandable microspheres are used as the fine particles, the heating temperature (T1) is preferably 10 ° C. or lower than the heat expansion temperature. By this heating treatment, a good adhesion holding force (adhesion with the first adherend 12) with respect to the first adherend 12 that is higher than the adhesive strength of the adhesive layer 3 on the second separator 7 side is developed.

  (3) Next, in this example, as shown in FIG. 5, the second adhesive sheet 11 in which the second separator 7 is separated from the second laminate 22 and the adhesive layer 3 is exposed on the first adherend 12 is formed. prepare. Then, as shown in FIG. 6, the 2nd adhesive sheet 11 is piled up on the 2nd to-be-adhered body 14 with the adhesive layer 3 facing, and the adherend laminated body by the 3rd laminated body 26 is obtained (3rd process). . The obtained adherend laminate is used for a desired purpose (for example, cutting, punching, printing, vapor deposition, etc.). Examples of the second adherend 14 include carrier glass, stainless steel plate, and epoxy sheet.

  According to the above method, since the pressure-sensitive adhesive sheet 1 of this example is used, it can be re-applied to the first adherend 12 any number of times, and the laminated body after correct positioning (in this example, the 1 ′ laminated body) Thus, it is possible to develop a good adhesion holding force (adhesion with the adherend) to the first adherend 12 by performing a predetermined heating process. Therefore, an adherend laminate in which the adherend does not fall off can be efficiently produced.

  In this example, the adherend laminate by the third laminate 26 manufactured using the specific pressure-sensitive adhesive sheet 1 (using a thermal foaming agent as the fine particles to be contained in the pressure-sensitive adhesive layer 3) has finished its intended use. When joining of the 1st to-be-adhered body 12 and the 2nd to-be-adhered body 14 becomes unnecessary, as shown in FIG. 7, what is necessary is just to heat-process the 3rd laminated body 26 (4th process). The heating temperature (T2) in the heat treatment is a temperature that is 10 ° C. or more higher than the temperature (T1) of the heat treatment applied to the first laminate 20. By such a heat treatment, as shown in FIG. 8, the tackiness of the front and back surfaces of the adhesive layer 3 is reduced, thereby causing contamination due to adhesive residue and the like due to the adhesive layer 3 to the first adherend 12 and the first adherend. The first adherend 12 and the second adherend 14 are uniformly peeled from the pressure-sensitive adhesive layer 3 without being generated on both the two adherends 14.

  The adherend laminate produced using the specific pressure-sensitive adhesive sheet 1 (using a thermal foaming agent as fine particles to be contained in the pressure-sensitive adhesive layer 3) has finished its intended purpose, and the first adherend 12 and the second adherend. When the joining of 14 becomes unnecessary, the tack on both the front and back surfaces of the adhesive layer 3 is appropriately reduced by applying a predetermined heat treatment. Thereby, the 1st to-be-adhered body 12 and the 2nd to-be-adhered body 14 can be peeled uniformly from the adhesion layer 3, without producing the contamination by the adhesive residue etc. resulting from the adhesion layer 3. FIG. The 1st to-be-adhered body 12 and the 2nd to-be-adhered body 14 which were uniformly peeled without the adhesive residue etc. from the adhesion layer 3 can be used for the next utilization.

  Hereinafter, the present invention will be specifically described based on experimental examples (including examples and comparative examples), but the present invention is not limited to these examples. “Part” and “%” are based on mass unless otherwise specified.

1. Preparation of pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet [Experimental Examples 1 to 11]
As the second separator 7, a polyethylene terephthalate (PET) sheet having a thickness of 100 μm whose surface was subjected to non-silicone mold release treatment was used. Each of the adhesive layer forming coating liquids a to k prepared by uniformly mixing and dissolving was applied with a baker type applicator. Table 1 shows the solid content ratio (mass conversion) of the adhesive and the like of each coating solution. The total solid content in each coating solution was adjusted to 40%. Thereafter, after sufficiently forming an adhesive layer by drying at 80 ° C., release of a PET sheet (first separator 5) having a thickness of 25 μm, one surface of which is subjected to silicone release treatment, on the surface of this adhesive layer By disposing the treated surface, the pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of each example were produced.

<< Constituent Components of Adhesive Layer Forming Coating Liquids a to k >>
-Adhesive, fine particles, tackifying resin and cross-linking agent: Table 1 type and solid content ratio-Solvent (toluene): 226 parts by mass

  In Table 1, “X1” of the pressure-sensitive adhesive is a polyacrylic ester resin (2-ethylhexyl acrylate-hydroxyethyl methacrylate copolymer (EHA / HEMA = 96.5 / 3.5), molecular weight: 520,000, Glass transition temperature: −65 ° C., OH value: 4.8, solid content 33%), “X2” is a polyacrylate resin (2-ethylhexyl acrylate-hydroxyethyl methacrylate copolymer (EHA / HEMA = 70 / 30), molecular weight: 390,000, glass transition temperature: −42 ° C., OH number: 6, solid content 42%). “X3” is a polyacrylate resin (acrylic acid-butyl acrylate copolymer (AA / BA = 20/80), molecular weight: 460,000, glass transition temperature: −31 ° C., acid value: 46, solid content 34%, manufactured by Nippon Carbide Corporation).

  “Y1” of the tackifier resin is a xylene-based tackifier resin (Nicanol HP150, softening point 170 ° C., molecular weight 1400, manufactured by Fudou), and “Y2” is a terpene phenol-based tackifier resin (YS polystar T160, softening point 160). “Y3” is a terpene phenol-based tackifier resin (YS Polystar G150, softening point 150 ° C., molecular weight 700, manufactured by Yasuhara Chemical Co., Ltd.).

  “Z1” of the fine particles has a mass average particle diameter of 13 μm, silica (Silicia 470, manufactured by Fuji Silysia Chemical Ltd.), and “Z2” has a mass average particle diameter of 13 μm and a thermal expansion temperature (synonymous with a thermal foaming temperature; the same applies hereinafter). ) Is 80 ° C. and the expansion ratio is 1.5 to 5 times thermally expandable microsphere (Matsumoto Microsphere, F-36D, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.), “Z3” has a mass average particle diameter of 12 μm, heat Thermally expandable microspheres (Matsumoto Microsphere, F-48D, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) having an expansion temperature of 100 ° C. and an expansion ratio of 1.5 to 5 times.

The “epoxy” of the crosslinking agent is tetrad X, N, N, N ′, N′-tetraglycidyl-m-xylenediamine (epoxy equivalent 100, manufactured by Mitsubishi Gas Chemical Company), and “isocyanate” is hexagonal. It is a trimer form of methylene diisocyanate and has an NCO content of 8% (3OCN (CH ₂ ) ₆ NCO (D-170N, manufactured by Takeda Pharmaceutical Company Limited).

2. Evaluation Regarding the pressure-sensitive adhesive composition and pressure-sensitive adhesive sheet of each example, the thickness of the pressure-sensitive adhesive layer, the surface roughness value of the pressure-sensitive adhesive layer, the peeling force and the bonding force, the reworkability (initial peelability), and the warm adhesion (warming) 6 items of adhesion after treatment) and heat peelability (peelability after heat treatment) were measured or evaluated by the following methods. The results are shown in Table 2.

(2-1) [Adhesive layer thickness]
Using a micrometer, the thickness including the two PET sheets was measured and calculated by subtracting the thickness of the two PET sheets from the measured value.

(2-2) [Surface roughness value of adhesive layer]
The pressure-sensitive adhesive sheet obtained in the experimental example was prepared, and one surface (first surface) of the pressure-sensitive adhesive layer peeled off and exposed from the first separator 5 and the pressure-sensitive adhesive layer peeled off and exposed from the second separator 7 Arithmetic average roughness (JIS B0601) in JIS B0601 using a laser microscope (VK-9510, Keyence Corporation) at three arbitrary positions (position n1, position n2, position n3) on the other surface (second surface). The value of Ra) was measured. Finally, the average (Ave.) of the three measured values was used as the Ra value on the surface side.

(2-3) [Peeling force (N / 25 mm) and bonding strength]
The peeling force a is the peeling force of the first separator 5 when the first separator 5 is peeled off under condition 1 to obtain the first pressure-sensitive adhesive sheet 10 with the pressure-sensitive adhesive layer 3 exposed on the second separator 7 ( This peel force a was measured.
The peeling force a1 is obtained by stacking the first pressure-sensitive adhesive sheet 10 on the first adherend (barrier film made of a polyethylene terephthalate film) 12 with the pressure-sensitive adhesive layer 3 being opposed to obtain the first laminated body 20, and then the first lamination. The peeling force of the first pressure-sensitive adhesive sheet 10 when the first pressure-sensitive adhesive sheet 10 was peeled off from the body 20 under Condition 2 (see FIG. 3), and this peeling force a1 was measured.
The peeling force a2 was obtained by applying a heating process to press one surface while heating the first laminated body 20 under the condition 3 to obtain the second laminated body 22, and then in the environment of 25 ° C. 22 is the peel force of the first pressure-sensitive adhesive sheet 10 when the first pressure-sensitive adhesive sheet 10 is peeled off (see FIG. 4), and this peel force a2 was measured.

The peeling force b is obtained when the second separator 7 is peeled from the second laminate 22 in an environment of 25 ° C. to obtain the second ′ pressure-sensitive adhesive sheet 11 a in which the pressure-sensitive adhesive layer 3 is exposed on the first adherend 12. The peeling force of the second separator 7 (see FIG. 5A), and this peeling force b was measured.
The peeling force b1 was obtained by stacking the second ′ pressure-sensitive adhesive sheet 11a on the second adherend (carrier glass) 14 with the pressure-sensitive adhesive layer 3 opposed to obtain a third ′ laminated body 26a, and then in an environment of 25 ° C. This is the peel force of the second ′ adhesive sheet 11a when the second ′ adhesive sheet 11a is peeled from the third ′ laminate 26a (see FIG. 6A), and this peel force b1 was measured.
The bonding force b2 is the same as that of the second 'adhesive sheet 11a of the third "laminate 26b and the second" when the third "laminate 26b is obtained by subjecting the third' laminate 26a to the heat treatment according to the condition 4. This is the bonding force with the adherend 14 (see FIG. 7A), and this bonding force b2 was measured.
The joining force a3 is a joining force between the third adhesive sheet 11b and the first adherend 12 with the adhesive layer 3 exposed on the second adherend 14 of the third "laminate 26b (see FIG. 7A). The bonding force a3 was measured.
Then, the numerical values of a, a1, a2, a3, b, b1 and b2 are compared, and the relationship A (a <a1 ≦ b <a2 ≦ b1) and the relationship A1 (a3≈b2 <a) are satisfied. Evaluated whether or not. Those that were satisfied were rated as “good”, and those that were not satisfied were rated as “bad”.

  Conditions 1 to 4 were as follows. Condition 1 is that the peeling environment is 25 ° C., the peeling direction is a direction of 180 degrees opposite to the direction in which one end of the first separator 5 faces one end, the peeling speed is 300 mm / min, The condition is that the width is 25 mm. Condition 2 is a condition in which the peeling environment is 25 ° C., and the time from when the first laminate 20 is obtained to the start of peeling is within one minute. Condition 3 is that the applied temperature is 60 ° C., the applied pressure is 0.3 MPa, and the time is 30 seconds. In condition 4, the heating temperature is 80 ° C. in experimental example 7, 100 ° C. in experimental example 8, a temperature higher by 10 ° C. than the temperature of the heating treatment in condition 3, and the heating time is 30 minutes.

(2-4) [Reworkability]
A polyethylene terephthalate film (thickness 100 μm, 10 cm × 10 cm, prepared as an adherend) was prepared by preparing an adhesive sheet obtained in an experimental example of 5 cm × 5 cm size, and peeling off the first separator 5 to expose the adhesive layer. When a 2 kg roller is applied to the surface of Lumirror T60 (Toray Industries, Inc.) and peeled off within 30 seconds, “○” indicates that the adhesive layer is peeled off together with the second separator 7, and the second separator 7 is peeled off and adhered. The layer remained on the film was marked “x”.

(2-5) [Adhesion after heating treatment]
In order to evaluate the adhesiveness after the rework, the adhesiveness with the adherend after the heating treatment was evaluated.
The pressure-sensitive adhesive sheet used in the evaluation of the reworkability was again bonded to the surface of the adherend over 30 seconds using a 2 kg roller heated to 60 ° C., and then allowed to stand until it returned to room temperature. In the evaluation, “O” indicates that the adhesive layer of the adhesive sheet is in close contact with the adherend and only the second separator 7 is easily peeled off, “Δ” indicates that only the second separator 7 is peeled off, and “ Only the separator 7 could not be peeled off, and the adhesive layer of the pressure-sensitive adhesive sheet was peeled off from the adherend as “x”.

(2-6) [Peelability after heat treatment]
A polyethylene terephthalate film (thickness: 100 μm, prepared by preparing the pressure-sensitive adhesive sheet obtained in Experimental Examples 10 and 11 of 2 cm × 10 cm and peeling and exposing the first separator 5 as a first adherend. 3 cm × 15 cm: pasted on the surface of Lumirror T60, manufactured by Toray Industries, Inc. Next, the adhesive layer peeled off and exposed from the second separator was attached to the surface of a glass plate (thickness 1.5 mm, 3 cm × 15 cm) prepared as a second adherend, and then an oven at 80 to 100 ° C. For 30 minutes. After standing to cool, at room temperature (23 ° C.), it was visually evaluated whether or not the adhesive layer of the adhesive sheet was peeled off from the first adherend and the second adherend. In the evaluation, “◯” indicates that the sample was peeled off, and “X” indicates that the sample was not peeled off.

  As shown in Table 2, in the pressure-sensitive adhesive sheets of Experimental Examples 1-8, 10, and 11, the weight-average molecular weight of the tackifying resin in the pressure-sensitive adhesive layer is 800 or more, and the surface roughness Ra of the pressure-sensitive adhesive layer is on both the front and back surfaces. It was 0.01 μm or more and 0.3 μm or less. Moreover, the peeling force of the adhesive layer satisfied the relationship of a <a1 ≦ b <a2 ≦ b1. That is, the peeling force of the adhesive layer satisfied the relationship A: a <a1 ≦ b <a2 ≦ b1. As a result, the reworkability was excellent and the adhesiveness after reworking (adhesion with the adherend after heating treatment) was also excellent.

  In particular, when Experimental Examples 1 to 3 and Experimental Example 4 are compared, in Experimental Examples 1 to 3 and 4, peeling forces a, a1 and b were 0.01 to 0.45 (N / 25 mm). The pressure-sensitive adhesive sheets of Experimental Examples 1 to 3 have peeling forces a2 and b1 of 0.25 to 1.50 (N / 25 mm), and the pressure-sensitive adhesive sheet of Experimental Example 4 has peeling forces a2 and b1 of 0.25 ( N / 25 mm). As a result, Experimental Examples 1 to 3 were superior to Experimental Example 4 in adhesion after reworking (adhesion with the adherend after heating treatment). However, the thing of Experimental example 4 was also able to endure practically enough.

Next, as in Experimental Example 2 and 3, a comparison of experimental examples 5 and 6 Experimental Examples 2 and 3, the most preferred range tackifying resin is 15 to 40 parts by mass with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive It is a thing of content, and Experimental example 5 and 6 was what tackifying resin contained exceeding 40 mass parts. As a result, towards the experimental examples 2 and 3 became that adhesion after rework than Experiment Examples 5 and 6 (adhesion to the adherend after heating treatment) were excellent.
Next, comparing Experimental Examples 7 and 8 with Experimental Example 9, in Experimental Example 9, the surface roughness Ra of the adhesive layer was 0.01 μm or more and 0.3 μm or less on both the front and back surfaces. Since the weight average molecular weight of the resin was less than 800 and the peeling force before heating of the adhesive layer did not satisfy the relationship A, the reworkability was inferior compared to the adhesive sheets of Experimental Examples 7 and 8.
In addition, since the pressure-sensitive adhesive sheets of Experimental Examples 10 and 11 used thermally expandable microspheres as fine particles to be contained in the pressure-sensitive adhesive layer, the peel force before heating of the pressure-sensitive adhesive layer has a relationship of a <a1 ≦ b <a2 ≦ b1. In addition to being satisfied, the bonding strength of the adhesive layer after heating was a3 = b2, and the relationship of a3 = b2 <a was also satisfied. That is, the peeling force before heating of the adhesive layer satisfied the relationship A: a <a1 ≦ b <a2 ≦ b1, and the bonding force of the adhesive layer after heating satisfied the relationship A1: a3≈b2 <a. As a result, in addition to excellent reworkability and adhesiveness after reworking (adhesiveness with the adherend after heating treatment), it was excellent in heat peelability.

1 ... Adhesive sheet,
3 ... Adhesive layer,
5 ... 1st separator,
7 ... second separator,
10 ... 1st adhesive sheet (7, 3),
11 ... 2nd adhesive sheet (12, 3),
11a 2nd adhesive sheet (12, 3),
11b ... Third adhesive sheet (14, 3)
12 ... first adherend,
14 ... second adherend,
20 ... 1st laminated body (10, 12),
22 ... 2nd laminated body (20),
26: third laminate (12, 3, 14),
26a ... 3 'laminate (11a, 14),
26b ... 3rd "laminate.

Claims (5)

In the pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer in which the adhesive force of the contact surface with the adherend changes before and after heating is disposed between the first separator and the second separator,
The pressure-sensitive adhesive layer contains at least an acrylic pressure-sensitive adhesive, fine particles, and a tackifier resin having a weight average molecular weight of 800 or more, and the compounding amount of the tackifier resin is 15 to 40 parts by mass with respect to the adhesive of 100 parts by mass. Formed of a certain pressure-sensitive adhesive composition, and the surface roughness of one surface is adjusted to 0.01 μm or more and 0.3 μm or less,
When the first separator is separated from the adhesive sheet and the adhesive layer exposed on the second separator is bonded to a PET film using a 2 kg roller and then separated within 30 seconds, the second separator is not separated from the adhesive layer. And the rework property in which the second separator and the adhesive layer are integrally separated from the PET film in a state where no adhesive residue is produced on the PET film,
The first separator is separated from the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer exposed on the second separator is bonded to a PET film over 30 seconds using a 2 kg roller heated to 60 ° C., and then returned to room temperature (23 ° C.). A pressure-sensitive adhesive sheet characterized by having an adhesiveness after a heating treatment in which only the second separator is separated in a state where the pressure-sensitive adhesive layer is not separated from the PET film when separated. The pressure-sensitive adhesive sheet according to claim 1, wherein the fine particles are a thermal foaming agent having a thermal foaming temperature of 50 ° C. or more and 100 ° C. or less.   The pressure-sensitive adhesive sheet according to claim 2, wherein microencapsulated thermally expandable microspheres are used as the thermal foaming agent, and the standard deviation of the particle size distribution of the thermally expandable microspheres is 5.0 µm or less. In the manufacturing method of the adherend laminate using the adhesive sheet according to any one of claims 1 to 3,
After separating the first separator from the pressure-sensitive adhesive sheet to obtain a first pressure-sensitive adhesive sheet with the pressure-sensitive adhesive layer exposed on the second separator, the first pressure-sensitive adhesive sheet is overlapped with the pressure-sensitive adhesive layer on the first adherend. A first step of obtaining a first laminate;
After separating the first pressure-sensitive adhesive sheet from the first laminate and changing the stacking position with the first adherend, the first adhesive sheet is again piled on the first adherend to obtain a first ′ laminate;
While heating the first 'laminate to 40 ° C. or higher and 180 ° C. or lower (however, when the adhesive layer contains a thermal foaming agent, the temperature is 10 ° C. or lower than the thermal foaming temperature of the thermal foaming agent) A second step of obtaining a second laminate by applying a heating treatment to press the surface;
The second separator is separated from the second laminate to obtain a second pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer exposed on the first adherend, and then the second pressure-sensitive adhesive layer is opposed to the second pressure-sensitive adhesive layer. A method for producing an adherend laminate, comprising: a third step of obtaining an adherend laminate by a third laminate, and overlapping the body. From the temperature of the heating process performed by the 2nd process by Claim 4 to the adherend laminated body by the 3rd laminated body manufactured by the method of Claim 4 using the adhesive sheet of Claim 2 or 3. Heat treatment is performed at a temperature higher by 10 ° C. or higher (but only when the temperature is higher than the thermal foaming temperature of the thermal foaming agent), and each of the first adherend, the adhesive layer and the second adherend is separated. A method for treating an adherend laminate.