JP6637762B2 - set - Google Patents

Description

  The present invention relates to sets, and more particularly to removable adhesive sets.

  In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid (viscoelastic body) state in a temperature range around room temperature, and has a property of easily adhering to an adherend by pressure. Taking advantage of such properties, the pressure-sensitive adhesive is preferably used in the form of a pressure-sensitive adhesive sheet, for example, for fixing components in portable electronic devices such as mobile phones, smartphones, and tablet computers. Further, the pressure-sensitive adhesive sheet attached to the adherend can be removed from the adherend at the time of repair, replacement, inspection, recycling, and the like of the adherend and its peripheral members. Patent Literatures 1 to 6 are known as literatures that disclose the prior art relating to this type of removable adhesive sheet. Patent Literature 1 relates to a medical pressure-sensitive adhesive sheet to be attached to the skin.

JP-T-2005-500133 JP 2000-96006 A JP 2000-96007 A JP 2002-235046 A JP 2002-235058 A JP 2010-53917 A

  When removing the pressure-sensitive adhesive sheet from the adherend, it is desirable that the removal operation be completed without deformation or breakage of the adherend regardless of the strength of the adherend. As one of the means, Patent Documents 2 to 6 disclose methods using an extensible pressure-sensitive adhesive sheet. In this method, the adhesive sheet is stretched and deformed by holding and pulling the end of the extensible adhesive sheet to reduce the adhesive area. As a result, the adhesive sheet is removed from the adherend. Since this pressure-sensitive adhesive sheet has extensibility, the load on the adherend when the pressure-sensitive adhesive sheet is peeled off is significantly reduced. For example, when the extensible pressure-sensitive adhesive sheet is used for joining two objects, if the tensile direction of the pressure-sensitive adhesive sheet during removal of the extensible pressure-sensitive adhesive sheet is substantially parallel to the joining surface of the object, the extensible pressure-sensitive adhesive sheet is It can be removed so as to be pulled out between two objects. Such pull-out peeling is an ideal removal because all the pulling force of the extensible pressure-sensitive adhesive sheet is used for pulling out and elongating (stretching) the pressure-sensitive adhesive sheet.

  However, when the adhesion portion and the peripheral space of the stretchable adhesive sheet are limited, the stretchable adhesive sheet cannot be pulled in parallel to the joining surface of the two objects, and the non-stretching adhesive sheet cannot be pulled with respect to the joining surface. Pulling the stretchable adhesive sheet at a parallel angle will remove the stretchable adhesive sheet. At this time, the extensible pressure-sensitive adhesive sheet is stretched while being pressed against an end of one of the objects to be adhered, and is peeled off. In such a case, depending on the end shape and material of the adherend, a load is applied to the end of the adherend in accordance with the pulling angle with respect to the joint surface. As a result, the pull-out property may be reduced, and the adherend may be deformed or damaged, or the extensible pressure-sensitive adhesive sheet may be cut off.

  The present invention has been made in view of the above circumstances, and even in the case of pulling off at a non-parallel angle with respect to the joint surface of the adherend, it is possible to smoothly peel off the adherend. It is an object of the present invention to provide a set that is not deformed or damaged, and is hard to cut the stretchable adhesive sheet.

  According to the present invention, a double-sided adhesive extensible pressure-sensitive adhesive sheet for joining one object and another object, and an elongation provided at an end of a surface to be adhered of one of the one object and the other object And an auxiliary film. The thickness of the stretch assisting film is less than 230 μm. By providing an extension assisting film having a thickness equal to or less than a predetermined value at the end of the adhered surface of the object to be adhered, at the time of removing the extensible pressure-sensitive adhesive sheet, at a non-parallel angle to the joining surface of the object. When the pressure-sensitive adhesive sheet is pulled, the extensible pressure-sensitive adhesive sheet comes into contact with the stretch assisting film at the end of the surface to be bonded. Due to the presence of the stretch assisting film, the above-mentioned tensile force is efficiently used for stretching the stretchable pressure-sensitive adhesive sheet regardless of the shape of the end portion of the adherend, the material, and the like. Since the elongation of the extensible pressure-sensitive adhesive sheet contributes to the peeling of the extensible pressure-sensitive adhesive sheet through the reduction of the adhesive area, the peeling of the extensible pressure-sensitive adhesive sheet can be smoothly performed by utilizing the above-described elongation. At the same time, the load at the end of the adherend due to the above-described tension is reduced, contrary to the elongation of the extensible pressure-sensitive adhesive sheet. This action, together with the function of the extension assisting film as a cushioning material between the end of the adherend and the extensible adhesive sheet, prevents deformation or breakage of the adherend. In addition, the extensible pressure-sensitive adhesive sheet is also difficult to be cut by the presence of the extension assisting film.

  The “set” in this specification is also referred to as a re-peelable adhesive set because the purpose is to re-peel (removal or removal) the pressure-sensitive adhesive sheet used for adhesion (typically, bonding). Further, in this specification, “removable” means that it can be removed from an adherend. More specifically, from the state in which one object and another object are joined by an extensible adhesive sheet, to release the joined state of one object and another object by pulling the adhesive sheet, It means that the extensible pressure-sensitive adhesive sheet can be peeled (removed) from the adherend by the above-mentioned pulling. "Removable" is basically synonymous, and the extensible pressure-sensitive adhesive sheet disclosed herein can be referred to as a re-peelable extensible pressure-sensitive adhesive sheet. The term “peeling” in this specification typically refers to peeling from an adherend by pulling (also referred to as pulling-out) or peeling by pulling-out operation (also referred to as pulling-out). . In addition, “adhesion” in this specification typically refers to adhesion for joining one object to another object by using an adhesive action. Further, the “object” in this specification may be two places of one article or one member. The “one object” and the “other object” may each be one object, or one or both may be two or more objects.

  In a preferred embodiment of the technology disclosed herein (including a set, a joining method, a joining release method, and the like; the same applies hereinafter), the coefficient of kinetic friction on the back surface of the stretch assisting film is 0.20 or less. With this configuration, when the extensible pressure-sensitive adhesive sheet is removed, when the stretchable pressure-sensitive adhesive sheet is pulled at a non-parallel angle to the joining surface of the object, the load on the end of the adherend surface of the adherend is reduced. Reduce. As a result, deformation or breakage of the adherend is preferably prevented. In addition, the extensible pressure-sensitive adhesive sheet is also more difficult to cut. At the same time, the force for pulling the extensible pressure-sensitive adhesive sheet is effectively assigned to the elongation of the extensible pressure-sensitive adhesive sheet, and therefore, the smooth peeling of the extensible pressure-sensitive adhesive sheet is preferably realized by utilizing the elongation of the pressure-sensitive adhesive sheet.

  In a preferred aspect of the technology disclosed herein, the extensible pressure-sensitive adhesive sheet exhibits a shear adhesive strength of 0.5 to 5 MPa. The effect of the technology disclosed herein is preferably exhibited in a configuration using an extensible pressure-sensitive adhesive sheet having an adhesive force within a predetermined range.

  In a preferred aspect of the technology disclosed herein, the extensible pressure-sensitive adhesive sheet includes an adhesive portion that joins the one object and the other object, and an exposed portion that protrudes from between the joined objects. Have. With the configuration described above, in a state where one object and another object are joined with the extensible adhesive sheet interposed therebetween, the extensible adhesive sheet is elongated by pulling the exposed portion, The joined state between the object and the other object is released. In other words, the adhesive portion of the extensible pressure-sensitive adhesive sheet can be stretched by pulling the exposed portion in a state where the one object and the other object are joined by the adhesive portion, The bonding portion is configured so that the joined state of the one object and the other object is released by the extension thereof.

  In a preferred aspect of the technology disclosed herein, it is preferable that the extensible pressure-sensitive adhesive sheet and the extension assisting film have a band shape extending linearly. Further, it is more preferable that the stretch assisting film is arranged so that a longitudinal direction thereof intersects a longitudinal direction of the extensible pressure-sensitive adhesive sheet. And it is more preferable that the length of the stretch assisting film is equal to or longer than the width of the stretchable pressure-sensitive adhesive sheet. With such a configuration, when the extensible pressure-sensitive adhesive sheet is removed, an event that the extensible pressure-sensitive adhesive sheet deviates from the stretch assisting film and contacts an object is preferably prevented.

  In a preferred aspect of the technology disclosed herein, the extensible pressure-sensitive adhesive sheet includes a plurality of pressure-sensitive adhesive sheet pieces arranged at intervals. With such a configuration, one object and two or more other objects can be joined. Also, in joining one object and another object, a good joining function can be exhibited with a smaller bonding area.

  In a preferred aspect of the technology disclosed herein, the stretch assisting film includes a resin base constituting a back surface of the stretch assisting film, and an adhesive layer provided on one surface of the resin base. By providing the stretch assisting film having the above structure at the end of the surface to be adhered of the object to be adhered, at the time of removing the stretchable adhesive sheet, the stretchable adhesive film is formed at a non-parallel angle to the joining surface of the object. When the sheet is pulled, smoother peeling is realized. In addition, deformation or breakage of the adherend is preferably prevented, and the extensible pressure-sensitive adhesive sheet is also more difficult to cut.

  In a preferred aspect of the technology disclosed herein, in the extension assisting film, the resin base is a fluororesin film or an ultrahigh molecular weight polyethylene film. By using the resin material as the base material of the stretch assisting film, the dynamic friction coefficient on the back surface of the stretch assisting film decreases. As a result, when the extensible pressure-sensitive adhesive sheet is removed, even if the extensible pressure-sensitive adhesive sheet is pulled at a non-parallel angle with respect to the joining surface, the load on the end of the adhered surface of the adhered object is suppressed to a low level, resulting in smoother operation. The real peeling is realized.

  In a preferred embodiment of the technology disclosed herein, the extension assisting film has a thickness of 150 μm or less. Since the thickness of the stretch assisting film is further limited, the stretch assisting film does not hinder the joining by the stretchable pressure-sensitive adhesive sheet and does not hinder smooth peeling when removing the stretchable pressure-sensitive adhesive sheet.

  In a preferred aspect of the technology disclosed herein, the extensible pressure-sensitive adhesive sheet, from a state in which the one object and the other object are joined, with respect to a joint surface between the one object and the other object At an angle of 45 ° or more. More specifically, the extensible pressure-sensitive adhesive sheet has an angle of 45 ° or more with respect to a bonding surface between the one object and the other object from a state where the one object and the other object are bonded. A structure in which the joint between the one object and the other object can be released by pulling the object, and the object can be removed from between the one object and the other object Can be When the extensible pressure-sensitive adhesive sheet is pulled at the above angle during the removal of the extensible pressure-sensitive adhesive sheet, the extensible pressure-sensitive adhesive sheet is peeled off while being pressed against the end of the adherend. Therefore, both the adherend and the extensible pressure-sensitive adhesive sheet may be damaged. According to the above configuration, since the extension assisting film is provided on the adherend, damage to the adherend and the extensible pressure-sensitive adhesive sheet is reduced. Further, since the thickness of the stretch assisting film is limited to a predetermined value or less, it does not prevent smooth peeling of the stretchable adhesive sheet.

  The set disclosed herein is preferably used for a portable electronic device. According to the set disclosed herein, even in the case of being peeled by being pulled at a non-parallel angle with respect to the joining surface of the adherend, it is possible to smoothly peel off the extensible pressure-sensitive adhesive sheet. Deformation and breakage of the body are prevented, and the stretchable adhesive sheet is difficult to cut. Utilizing this feature, it is particularly preferably used in battery fixing applications where there are many chances of being removed at the time of repair or replacement of members constituting an electronic device, product inspection, and the like. According to the technique disclosed herein, there is provided a set preferably used for fixing a battery. Therefore, according to the present specification, a portable electronic device in which a member (for example, a battery) is fixed by an extensible adhesive sheet is provided. In this portable electronic device, an extension assisting film is fixed to an end portion of the member to be adhered. Further, the stretch assisting film can come into contact with the stretch adhesive sheet at least when the stretch adhesive sheet is peeled off.

  Further, according to the present specification, a double-sided adhesive extensible pressure-sensitive adhesive sheet for joining one object and another object, and one end of the one object and the other object on the surface to be adhered. And a stretch assisting film to be provided. The stretch assisting film has a portion whose thickness decreases toward the end. By providing the extension auxiliary film at the end of the adhered surface of the object to be adhered, when removing the extensible adhesive sheet, when the adhesive sheet is pulled at an angle non-parallel to the joining surface of the object The extensible pressure-sensitive adhesive sheet is peeled off at the end of the surface to be adhered while contacting the extension assisting film. Due to the presence of the stretch assisting film, the above-mentioned tensile force is efficiently used for stretching the stretchable pressure-sensitive adhesive sheet regardless of the shape of the end portion of the adherend, the material, and the like. Since the elongation of the extensible pressure-sensitive adhesive sheet contributes to the peeling of the extensible pressure-sensitive adhesive sheet through the reduction of the adhesive area, the peeling of the extensible pressure-sensitive adhesive sheet can be smoothly performed by utilizing the above-described elongation. Further, since the stretch assisting film has a portion where the thickness is reduced (thickness reducing portion), the stretch assisting film is attached to the end of the surface to be bonded so that the reduced thickness portion comes into contact with the stretchable adhesive sheet. In this case, it is possible to suppress a decrease in the peeling property due to the thickness of the extension assisting film. Also, contrary to the stretching of the stretchable adhesive sheet, the load at the end of the adherend with respect to the above-described tension is reduced, so that the stretch assisting film serves as a cushioning material between the end of the adherend and the stretchable adhesive sheet. In conjunction with functioning, deformation or breakage of the adherend is prevented. The extensible pressure-sensitive adhesive sheet is also difficult to be cut by the presence of the extension assisting film.

  Further, according to the present invention, there is provided a method for releasably joining one object and another object. The method comprises the steps of providing a stretchable pressure-sensitive adhesive sheet and a stretch assisting film; attaching the stretch assisting film to an end of a surface to be bonded of one of the one object and the other object; Attaching an adhesive portion of the extensible pressure-sensitive adhesive sheet to the one object and the other object. In addition, the stretch assisting film, when the stretch adhesive sheet is removed, when the stretch adhesive sheet is pulled at an angle that is non-parallel to the joining surface of the object, the stretch assist film is stretched at the end of the adhered surface. It is arranged so as to be in contact with the adhesive sheet. The extensible pressure-sensitive adhesive sheet affixed to the object by this method can be peeled off smoothly even when it is pulled off at a non-parallel angle to the joint surface of the adherend, and the adherend is deformed. Or it is not broken, and the extensible adhesive sheet is hard to cut. Therefore, according to the above method, the joining and the releasing of the object can be preferably performed. In a preferred embodiment, the thickness of the stretch assisting film is less than 230 μm. In another preferred embodiment, the extension assisting film has a portion whose thickness decreases toward an end. With such a configuration, smoother peeling can be performed, and deformation and breakage of the adherend and breakage of the extensible pressure-sensitive adhesive sheet can be more preferably prevented.

  Further, according to the present invention, there is provided a method for releasing the joining between one object and another object joined by the extensible pressure-sensitive adhesive sheet. The extensible pressure-sensitive adhesive sheet has an adhesive portion that joins the one object and the other object, and an exposed portion that protrudes from between the joined objects. Further, the method includes a step of pulling the exposed portion in a state where the one object and the other object are joined with the extensible pressure-sensitive adhesive sheet interposed therebetween. The stretchable pressure-sensitive adhesive sheet is stretched by the pulling of the exposed portion, and the joined state between one object and another object is released. Here, an extension assisting film is previously attached to an end of the adhered surface of one of the one object and the other object. Specifically, the extension assisting film is attached to one object before joining one object to another object. The stretch assisting film is arranged to be in contact with the extensible pressure-sensitive adhesive sheet at the end of the surface to be adhered when the extensible pressure-sensitive adhesive sheet is pulled at a non-parallel angle to the joining surface of the object. I have. According to this method, even when the object to be adhered is pulled off at a non-parallel angle with respect to the joint surface, the presence of the extension assisting film allows the joined state of one object and another object to be smoothly released. can do. Further, in the release of the joined state, it is possible to prevent the adherend from being deformed or damaged and the extensible adhesive sheet from being broken. In a preferred embodiment, the thickness of the stretch assisting film is less than 230 μm. In another preferred embodiment, the extension assisting film has a portion whose thickness decreases toward an end. With such a configuration, smoother peeling can be performed, and deformation and breakage of the adherend and breakage of the extensible pressure-sensitive adhesive sheet can be more preferably prevented.

It is a side view which shows typically the example of 1 structure of the removable adhesive set in the state attached to the to-be-adhered body (object). It is the typical side view which looked at the removable adhesive set of FIG. 1 from the right. FIG. 2 is a partially enlarged view of FIG. 1, and is a side view for explaining release of a joined state between one object and another object joined by an extensible adhesive sheet. It is a figure corresponding to FIG. 2, and is a typical side view of the modification of a removable adhesive set. It is a typical side view which expands and shows a part of other modification of a removable adhesive set. It is a schematic side view for demonstrating one aspect of pulling removal, (a) is a figure which shows the state which starts pulling removal, (b) shows the state which pulls a tab and removes. It is a figure, (c) is a figure showing the state where tension removal was completed. It is a schematic top view for demonstrating one aspect of tension removal, (a) is a figure which shows the state which starts tension removal, and (b) shows the state which pulls a tab and removes. It is a figure and (c) is a figure showing the state where tension removal was completed. It is sectional drawing which shows typically the example of 1 structure of an extensible adhesive sheet. It is explanatory drawing which shows the measuring method of a shear adhesive force typically. It is explanatory drawing which shows typically the measuring method of tensile peeling stress B. It is sectional drawing which shows typically the example of 1 structure of an extension assistance film.

  Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than those specifically mentioned in the present specification and necessary for the practice of the present invention are based on the teachings of the practice of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in the field. In the following drawings, members and portions having the same function will be denoted by the same reference numerals and described, and redundant description may be omitted or simplified. In addition, the embodiment described in the drawings is schematically illustrated in order to clearly explain the present invention, and the size and the scale of the set and the extensible adhesive sheet of the present invention actually provided as a product and the extension auxiliary film are described. It is not always exactly represented.

In this specification, the term "pressure-sensitive adhesive" refers to a material which has a property of exhibiting a soft solid (viscoelastic body) state in a temperature range around room temperature and easily adhering to an adherend by pressure as described above. . The adhesive referred to here is generally a complex tensile modulus E ^* (1 Hz) as defined in "CA Dahlquist," Adhesion: Fundamental and Practice ", McLaren & Sons, (1966) P. 143. It is a material having a property satisfying <10 ⁷ dyne / cm ² (typically, a material having the above property at 25 ° C.).

  Further, in this specification, the term "stretchable pressure-sensitive adhesive sheet" refers to a pressure-sensitive adhesive sheet having such a degree of extensibility that an individual (standard adult) can hold and stretch. Typically, when the adhesive sheet is pulled in the shear direction in a state of being adhered to the adherend, the adhesive area with the adherend is reduced due to the extension of the adhesive sheet, and it is possible to finally peel off from the adherend. It may be a pressure-sensitive adhesive sheet having a possible degree of extensibility. Preferably, it may be a pressure-sensitive adhesive sheet showing an elongation at break described later. In addition, in this specification, "an extensible pressure sensitive adhesive sheet" may be abbreviated simply as "pressure sensitive adhesive sheet".

  Further, in this specification, the “band shape” refers to a shape extending linearly and having a width (length in a direction orthogonal to the direction extending linearly). The band shape is a shape having a predetermined length in the direction extending linearly and having a width shorter than the length, and is a concept including a rectangular shape and a strip shape. Therefore, the band shape can be rephrased as a long shape. The belt shape according to one embodiment has a shape extending linearly, but may have a shape extending curvedly, and may include a shape having a linearly extending portion and a curvedly extending portion. . The width of the band shape may not be constant.

  Further, in this specification, "tab" is used as a word meaning "knob" which is a starting point (pulling starting point) when the extensible pressure-sensitive adhesive sheet is pulled, and especially for other elements (shape, material, etc.). Not restricted. Usually, the tab has a size enough to be gripped by a finger and has a shape (for example, a flat rectangular shape) that can be gripped with a finger, but a mode in which the tab is pulled using a machine or an instrument may be used. Therefore, it is not necessary to have a size that can be gripped by a finger, and there is no limitation on the shape. For example, a tab having a perforation can have a small size because a hook can be inserted through the perforation and pulled. A typical tab is a continuous tab from the stretchable pressure-sensitive adhesive sheet, and preferably does not stretch by tension or has a lower stretchability, if any, than the stretchable pressure-sensitive adhesive sheet.

<Configuration of removable adhesive set>
FIG. 1 is a side view schematically showing a configuration example of a removable adhesive set in a state where the adhesive set is attached to an adherend (object). FIG. 2 is a schematic side view of the removable adhesive set of FIG. 1 as viewed from the right. FIG. 3 is a partially enlarged view of FIG. 1 and is a side view for explaining release of a joined state between one object and another object joined by an extensible adhesive sheet.

  The removable adhesive set disclosed herein may have a structure schematically shown in FIGS. The removable adhesive set 1 shown in FIG. 1 includes an extensible pressure-sensitive adhesive sheet 10 and an extension assisting film 50. The extensible pressure-sensitive adhesive sheet 10 has double-sided adhesiveness, and is used to join one object 80 and another object 90. In addition, the extensible pressure-sensitive adhesive sheet 10 can be removed again, and can be removed from the adherend after completing the joining purpose. This will be described later. The extension assisting film 50 is detachably fixed to the end of the adhered surface 80A of one of the objects 80 and the other object 90 joined by the extensible adhesive sheet 10. Therefore, the extension assisting film 50 is in contact with the extensible adhesive sheet 10.

  The extensible pressure-sensitive adhesive sheet 10 has a band shape extending linearly when viewed from above, and is adhered to the objects 80 and 90 while being sandwiched between the objects 80 and 90. In this embodiment, as the extensible pressure-sensitive adhesive sheet 10, a double-sided pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer on both sides of a substrate is used. The extensible pressure-sensitive adhesive sheet 10 has an adhesive portion 12 and an exposed portion 14. The bonding portion 12 is sandwiched between the objects 80 and 90, and the respective adhesive surfaces of the bonding portion 12 are bonded to the objects 80 and 90, respectively. Thereby, the objects 80 and 90 are joined. The exposed part 14 is located at one end in the longitudinal direction of the extensible adhesive sheet 10. The exposed portion 14 protrudes from between one object 80 and another object 90 to be joined. In other words, the exposure unit 14 is exposed outside the objects 80 and 90. The exposed portion 14 is not adhered to the object 80, but can be temporarily fixed by bringing the adhesive surface of the exposed portion 14 into contact with the outer surface of the object 80 when the objects 80 and 90 are joined. A tab (not shown) is provided at an end of the exposed portion 14.

  The extension assisting film 50 is a single-sided adhesive pressure-sensitive adhesive film. The back surface 50B of the extension assisting film 50 of this embodiment is made of a resin base material. Further, the thickness of the extension assisting film 50 is limited to less than 230 μm. Further, the extension assisting film 50 is detachably fixed to an end of a surface to be adhered of the object 80 (the surface to be adhered here is a surface to which the extensible pressure-sensitive adhesive sheet 10 is stuck) 80A. I have. Specifically, in the extension assisting film 50, the surface opposite to the back surface 50B is an adhesive surface (specifically, the surface of the adhesive layer) 50A, and the adhesive surface 50A is the adhered surface of the object 80. It is bent and attached so as to extend from an end of 80A to a part of a side surface 80B adjacent to the surface 80A to be bonded. Therefore, the extension assisting film 50 covers a part of the corner 80 </ b> C between the adhered surface 80 </ b> A of the object 80 and the adjacent side surface 80 </ b> B.

  In addition, the back surface 50B of the extension assisting film 50 is in contact with one adhesive surface of the extensible adhesive sheet 10 that joins one object 80 and another object 90. That is, a part of the extension assisting film 50 is located between one object 80 and another object 90. However, since the thickness of the extension assisting film 50 is limited as described above, there is no or little effect on the joining between the one object 80 and the other object 90 by the extensible adhesive sheet 10. The coefficient of kinetic friction of the back surface 50B of the extension assisting film 50 in contact with the adhesive surface is 0.20 or less. The size of the stretch assisting film 50 is such that the stretchable pressure-sensitive adhesive sheet 10 does not directly contact the end (typically, the corner 80C) of the surface 80A to be bonded of the object 80. In order not to hinder the joining by the extensible pressure-sensitive adhesive sheet 10, the adhesion area of the extension assisting film 50 on the surface 80A to be adhered is several mm or less from the corner 80C (approximately less than 10 mm, for example, 5 mm or less, and further 2 to 3 mm or less). ) Is preferably limited. The extension assisting film 50 of this embodiment has a rectangular shape, and its longitudinal direction is substantially parallel to the width direction of the extensible pressure-sensitive adhesive sheet 10. 2, the length of the extension assisting film 50 (the length in a direction intersecting (typically, substantially perpendicular to) the longitudinal direction of the extensible pressure-sensitive adhesive sheet 10. Typically, the extensible pressure-sensitive adhesive sheet Is preferably substantially equal to or longer than the width of the extensible pressure-sensitive adhesive sheet 10. In this embodiment, the length of the extension assisting film 50 is longer than the width of the extensible pressure-sensitive adhesive sheet 10.

  Next, a description will be given, with reference to FIGS. As shown in FIG. 1, the double-sided adhesive extensible pressure-sensitive adhesive sheet 10 has the adhesive portion 12 disposed between the objects 80 and 90 to join the objects 80 and 90 together. The extensible pressure-sensitive adhesive sheet 10 has an end protruding outside the objects 80 and 90 as an exposed portion 14. In this embodiment, a battery (more specifically, a polymer battery) is used as the object 80, and a portable electronic device body is used as the object 90. When it is desired to release the joined state of the objects 80 and 90 from this state, the exposed portion 14 of the extensible adhesive sheet 10 (more specifically, the tab provided on the exposed portion 14) is gripped, and Pull to pull out from between 90. At this time, in a case where the adhesion location and the peripheral space of the extensible pressure-sensitive adhesive sheet 10 are limited, as shown in FIG. (Eg, at an angle of 45 ° or more, typically 70-90 °). In particular, when the object 80 is a battery for a portable electronic device, such a situation is likely to occur because the space around the battery is generally narrow.

  When the extensible pressure-sensitive adhesive sheet 10 is pulled out by the above-described pulling operation, the extensible pressure-sensitive adhesive sheet 10 is pressed against the corner 80C of the object 80 located in the pulling direction (the direction of the arrow in FIG. 3). Here, since the extension assisting film 50 exists between the extensible pressure-sensitive adhesive sheet 10 and the corner 80C, the extensible pressure-sensitive adhesive sheet 10 extends while abutting on the back surface 50B of the stretching aid film 50, and is pulled. Peeled off. At this time, the extension assisting film 50 reduces the resistance (friction resistance) of the corner 80C to the extensible pressure-sensitive adhesive sheet 10 while protecting the end (typically the corner 80C) of the object 80. Therefore, the pulling force of the extensible pressure-sensitive adhesive sheet 10 is efficiently used for elongation of the extensible pressure-sensitive adhesive sheet 10. And since the extension of the extensible pressure-sensitive adhesive sheet 10 contributes to the peeling of the extensible pressure-sensitive adhesive sheet 10 through the reduction of the bonding area, the smooth peeling of the extensible pressure-sensitive adhesive sheet 10 is realized. Further, since the thickness of the extension assisting film 50 is limited to a predetermined value or less, a decrease in the peeling property due to the thickness of the extension assisting film 50 is suppressed. In the above-described peeling operation, contrary to the increase in the force used to stretch the extensible pressure-sensitive adhesive sheet 10, the resistance to the pulling at the corner 80C is reduced, and the deformation or breakage of the object 80 due to this resistance is caused. Is prevented. In addition, the extensible pressure-sensitive adhesive sheet 10 is also difficult to be cut by the presence of the extension assisting film 50.

  Next, a modification of the above embodiment will be described with reference to FIG. In the above embodiment, the removable adhesive set is constituted by one extensible pressure-sensitive adhesive sheet with respect to one stretch assisting film attached to the end of the object. The adhesive set 2 includes two extensible pressure-sensitive adhesive sheets for one elongation assisting film. Specifically, as shown in FIG. 4, the removable adhesive set 2 includes a plurality of (specifically, two) extensible pressure-sensitive adhesive sheets 10 (a plurality of extensible adhesive sheets) arranged between the objects 80 and 90. Each of the pressure-sensitive adhesive sheets may be referred to as a “pressure-sensitive adhesive sheet piece” in a sense of being distinguished from the stretchable pressure-sensitive adhesive sheet.) , Is provided. The plurality of extensible pressure-sensitive adhesive sheets 10 are arranged at intervals from each other. In this embodiment, the plurality of extensible pressure-sensitive adhesive sheets 10 have a band shape extending linearly, and are arranged substantially in parallel at intervals. In addition, each of the plurality of extensible pressure-sensitive adhesive sheets 10 joins the objects 80 and 90. Specifically, it is bonded to the objects 80 and 90 while being sandwiched between the objects 80 and 90. The stretch assisting film 50 also has a strip shape extending linearly, and the object 80 is covered so that its longitudinal direction intersects (specifically, substantially orthogonally) the width direction of the plurality of extensible adhesive sheets 10. It is attached to the end of the bonding surface 80A. The technology disclosed herein includes a configuration in which one stretch assist film 50 as described above is applied to two or more stretch adhesive sheets 10.

  Further, another modified example of the above embodiment will be described with reference to FIG. The extension assisting film 350 according to this modification is different from the above embodiment in that the thickness is changed. The extension assisting film 350 has a portion 352 whose thickness decreases toward the end (for convenience, also referred to as a “thickness decreasing portion” or a “gradual thickness decreasing portion”). Specifically, as shown in the figure, the extension assisting film 350 is bent and attached so as to extend over an end of the adhered surface 80A of the object 80 and a part of the adjacent side surface 80B of the adhered surface 80A. And covers a part of a corner 80C between the adhered surface 80A of the object 80 and the adjacent side surface 80B. A part (thickness reduction portion) 352 of the portion to be attached to the surface 80A is configured such that its thickness decreases as the distance from the corner 80C increases. Specifically, the thickness of the thickness reduction portion 352 is reduced in a slope shape. Since the direction in which the thickness decreases is opposite to the direction in which the extensible adhesive sheet 10 is pulled out, when the extensible adhesive sheet 10 is pulled to release the joined state of the objects 80 and 90, the extensible adhesive sheet 10 is pulled out. The sheet 10 is pulled out while being in contact with the extension assisting film 350 and the slope portion of the extension assisting film 350. Accordingly, it is possible to prevent an event that the extensible pressure-sensitive adhesive sheet 10 is caught on a step formed by the thickness of the extension assisting film 350 and the peelability of the extensible pressure-sensitive adhesive sheet 10 is reduced. In this modification, the thickness of the extension assisting film 350 is not particularly limited due to the presence of the thickness reducing portion 352.

  In the above-described embodiment, the removable adhesive set includes one stretchable pressure-sensitive adhesive sheet and one stretchable auxiliary film. However, the present invention is not limited to this. It may include an extension assisting film and a plurality of extensible pressure-sensitive adhesive sheets. Further, in the above-described embodiment, the removable adhesive set joins one object and another object, but the technology disclosed herein is not limited to this. For example, one object and another object may be two places of one article or one member. In addition, the one object and the other object may each be one object, or one or both may be two or more objects.

  Further, in the above embodiment, the pressure-sensitive adhesive sheet constituting the re-peelable adhesive set was a double-sided adhesive stretchable pressure-sensitive adhesive sheet having a band shape, but the shape of the stretchable pressure-sensitive adhesive sheet disclosed herein is not limited to this. Not limited. The extensible pressure-sensitive adhesive sheet may have, for example, a square shape, or may have a band-like portion in part. The extensible pressure-sensitive adhesive sheet typically has a shape extending linearly as in the above embodiment, but is not limited thereto, and may have a shape extending in a curved shape or a shape having a straight line and a curved line (for example, (Shape, U-shape, arc, wave, zigzag, etc.).

  Further, in the above embodiment, the surface of the exposed portion of the extensible pressure-sensitive adhesive sheet has tackiness, but the technology disclosed herein is not limited to this. The surface of the exposed portion and the surface of the bonded portion may be made of the same material (typically, an adhesive having the same composition) or may be made of different materials. The surface of the exposed portion may be non-tacky or low-tacky. Here, that the surface of the exposed part has low tackiness means that the adhesive strength (typically, peel strength with respect to SUS180 degrees) is lower than that of the surface of the bonding part. For example, the surface of the exposed portion can be made non-adhesive or low-adhesive by coating the adhesive surface of the exposed portion with powder or covering the adhesive surface with a thin film such as a resin film. When the extensible pressure-sensitive adhesive sheet is a pressure-sensitive adhesive sheet with a substrate, the surface of the exposed portion is made non-adhesive or low-adhesive by not forming an adhesive layer or removing the formed adhesive layer. can do. In this case, the exposed portion may be formed only of the base film having no pressure-sensitive adhesive layer.

  In the above embodiment, the extension assisting film is a single-sided adhesive film, but the technology disclosed herein is not limited to this. For example, the stretching aid film itself is a non-adhesive or low-adhesive resin film, and may be fixed to the adherend using an adhesive means such as a known or commonly used adhesive. In the above embodiment, the kinetic friction coefficient of the entire back surface of the stretch assist film is equal to or less than a predetermined value. The coefficient only needs to be equal to or less than a predetermined value. For example, the extension assisting film may have a kinetic coefficient of friction equal to or less than a predetermined value only in a part of the back surface including a portion in contact with the extensible pressure-sensitive adhesive sheet.

  Further, in the above embodiment, the extension assisting film is attached to the end of the object located above the one object and the other object, but the technology disclosed herein is not limited to this, The film may be attached to an object located on the side where the extensible pressure-sensitive adhesive sheet is pulled. Alternatively, the stretching aid film may be attached to both one object and the other.

  In the above embodiment, the tab is provided, but the tab may not be provided. When tabs are provided, the tabs can be appropriately designed according to the purpose and the like within a range described later. Alternatively, it is also possible to use the extensible pressure-sensitive adhesive sheet itself as a tab by performing a process of making the surface of the extensible pressure-sensitive adhesive sheet non-adhesive or low-adhesive. Further, in the above embodiment, the tab is fixed to one end in the longitudinal direction of the extensible pressure-sensitive adhesive sheet having a band shape, but the present invention is not limited to this. The tab can be provided at any place where the stretchable adhesive sheet can be pulled. For example, the tabs may be provided at both ends in the longitudinal direction of the stretchable pressure-sensitive adhesive sheet having a band shape.

<Pull-out of stretchable adhesive sheet>
The extensible pressure-sensitive adhesive sheet constituting the removable adhesive set disclosed herein is excellent in the ability to be pulled out from between objects to be removed (pull-out removability). Here, the pull-out removal property means that a tab of the adhesive sheet is exposed from one object and another object fixed with the extensible adhesive sheet therebetween, and the exposed tab is pulled to pull out the extensible adhesive sheet. This refers to the ease of removal such as releasing the fixation (typically joining) of the object. In addition, one object and another object may be two places of one member. In particular, according to the technology disclosed herein, smooth peeling is possible even when the film is pulled off at a non-parallel angle with respect to the joint surface of the adherend. Further, at the time of pull-out, the phenomenon that the extensible pressure-sensitive adhesive sheet is broken or the adherend is deformed or damaged is preferably prevented. Hereinafter, a more specific description will be given with reference to FIGS.

  FIG. 6 is a schematic side view for explaining one mode of pull-out (typically, pull-out), and FIG. 6 (a) is a diagram showing a state in which pull-out of an extensible pressure-sensitive adhesive sheet is started. (B) is a diagram showing a state in which the tab is being pulled to remove, and (c) is a diagram showing a state in which the tensile removal of the extensible pressure-sensitive adhesive sheet is completed. FIGS. 7A to 7C are schematic top views for explaining one mode of pull-out (typically, pull-out). FIGS. 7A to 7C respectively show FIGS. 7A to 7C. It is a corresponding figure.

  As shown in FIGS. 6A and 7A, the extensible pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) 110 is exposed to the outside when one object 180 and another object 190 are joined. A tab T is provided. The object 180 is joined to the object 190 using the extensible adhesive sheet 110. Prior to this joining, an extension assisting film 150 is attached to an end of the adhered surface 180A of the object 180. Then, when it is desired to release the bonded state between the object 180 and the object 190 for the purpose of repair, replacement, or the like, the extensible adhesive sheet 110 is pulled out from between the object 180 and the object 190. Specifically, the extensible adhesive sheet 110 is pulled so that the tab T is pinched with a finger and pulled out from between the objects 180 and 190. At this time, in order to realize smooth peeling, it is preferable that the stretching direction of the extensible pressure-sensitive adhesive sheet 110 is substantially parallel to the joining surface of the objects 180 and 190. However, in the case where the adhesion location of the extensible pressure-sensitive adhesive sheet and the surrounding space are limited, as shown in FIG. At an angle of 45 degrees or more and 90 degrees or less).

  When the extensible pressure-sensitive adhesive sheet 110 is pulled as described above, the extensible pressure-sensitive adhesive sheet 110 starts to expand, contracts in a direction perpendicular to the pulling direction, and starts to peel off from the objects 180 and 190 (FIG. 6B, FIG. 7 (b)). At this time, the extensible pressure-sensitive adhesive sheet 110 tries to press against the end of the adhered surface 180A of one of the objects 180, which is the adherend, but the extension auxiliary film 150 is attached to the end of the object 180. Therefore, it extends while being in contact with the back surface of the auxiliary film 150 and is peeled off. Here, by limiting the thickness of the extension assisting film 150 to a predetermined value or less, the resistance of the extensible adhesive sheet 110 to tension is reduced, and the extensible adhesive sheet 110 is smoothly pulled out. Finally, the entire adhesive area of the extensible pressure-sensitive adhesive sheet 110 is peeled off, and pulling out of the extensible pressure-sensitive adhesive sheet 110 from between the objects 180 and 190 is completed (see (c) of FIG. 6 and (c) of FIG. 7). ). Removal of the object 180 joined to the object 190 is also completed at the same time. In addition, the extension assisting film 50 attached to the end of the object 180 is separately removed by hand or the like as necessary.

<Structure of extensible adhesive sheet>
The extensible pressure-sensitive adhesive sheet constituting the removable adhesive set disclosed herein is, for example, a double-sided pressure-sensitive adhesive sheet with a base having a pressure-sensitive adhesive layer on both sides of a film-shaped substrate (support). Here, the concept of the pressure-sensitive adhesive sheet may include what is called a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, or the like. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet. Alternatively, the pressure-sensitive adhesive sheet may be a form processed into various shapes.

  The extensible pressure-sensitive adhesive sheet disclosed herein may have, for example, a cross-sectional structure schematically shown in FIG. In the extensible pressure-sensitive adhesive sheet 210 shown in FIG. 8, pressure-sensitive adhesive layers 231 and 232 are provided on each surface (all of which are non-peelable) of the film-like base material 220. The stretchable pressure-sensitive adhesive sheet 210 before use has a configuration in which each surface (each pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layers 231 and 232 is protected by a release liner (not shown). Alternatively, although not particularly shown, the extensible pressure-sensitive adhesive sheet disclosed herein may be a substrate-less double-sided pressure-sensitive adhesive sheet comprising only a pressure-sensitive adhesive layer.

  Further, it is preferable that the extensible pressure-sensitive adhesive sheet has a long portion (which may be a band portion or a rectangular portion; the same applies hereinafter) from the viewpoint of the tensile removability. Thereby, in the extensible pressure-sensitive adhesive sheet adhered to the adherend, the stretchable adhesive sheet is preferably pulled from the adherend by grasping and pulling one end in the longitudinal direction of the elongated portion. can do. The shape of the elongated portion is typically a band. From the viewpoint of removability by pulling, the elongated portion may have a shape that tapers toward one end in the longitudinal direction. In a more preferred embodiment, the extensible pressure-sensitive adhesive sheet is typically formed in a long shape.

<Size of extensible adhesive sheet>
When the extensible pressure-sensitive adhesive sheet disclosed herein has a long shape (a band shape or a rectangular shape; the same applies hereinafter) when used, its width is 30 mm or less (for example, 20 mm or less, typically 15 mm or less). To a degree. For example, when the stretchable adhesive sheet is used in a portable electronic device, the above width can be preferably adopted. When the extensible pressure-sensitive adhesive sheet has a breaking strength equal to or higher than a predetermined value, its width can be set to 10 mm or less (for example, 5 mm or less, and further 3 mm or less). In addition, from the viewpoint of preventing damage such as breakage at the time of tensile removal, the width of the extensible pressure-sensitive adhesive sheet is preferably 1 mm or more (for example, 3 mm or more, typically 5 mm or more), and preferably 10 mm or more (for example, 12 mm or more). Is more preferable.

  When the extensible pressure-sensitive adhesive sheet disclosed herein has a long shape, the length is preferably 1 cm or more (for example, 3 cm or more, typically 5 cm or more) from the viewpoint of removal workability by pulling. . Further, from the viewpoint of removal workability, the length of the extensible pressure-sensitive adhesive sheet is preferably 30 cm or less (for example, 15 cm or less, typically 5 cm or less).

  The ratio (L / W) of the length L to the width W of the extensible pressure-sensitive adhesive sheet is preferably 1 or more. The stretchable pressure-sensitive adhesive sheet having such a shape can exhibit a good adhesive function to a rectangular adherend (for example, a battery or the like). Further, it is more preferable that the extensible pressure-sensitive adhesive sheet has a band shape (typically a rectangular shape) as in the above embodiment. In this case, the stretchable pressure-sensitive adhesive sheet having the above ratio (L / W) of about 2 or more (typically 3 or more, for example, 5 or more) is removed depending on the shape and size of the adherend and the place of application. It tends to be excellent in properties and handling. Although the upper limit of the ratio (L / W) is not particularly limited, the ratio (L / W) can be about 50 or less (for example, 30 or less, typically 20 or less) from the viewpoint of strength, handleability, and the like. .

  The total thickness of the extensible pressure-sensitive adhesive sheet (including the pressure-sensitive adhesive layer and the base material, but not including the release liner) disclosed herein is not particularly limited, and may be approximately 20 μm or more (for example, 40 μm or more). It is appropriate that the thickness is approximately 5 mm or less (for example, 1000 μm or less). The total thickness of the extensible pressure-sensitive adhesive sheet is preferably about 50 μm or more (for example, 70 μm or more), and preferably about 300 μm or less (for example, 200 μm or less) in consideration of the adhesive property and the like. When the total thickness of the extensible pressure-sensitive adhesive sheet is not more than a predetermined value, it may be advantageous in terms of thinning, miniaturization, weight reduction, resource saving, and the like of the product. In another preferred embodiment, the total thickness of the extensible pressure-sensitive adhesive sheet may be 80 μm or more (eg, 100 μm or more, typically 130 μm or more), and more than 150 μm (eg, more than 300 μm, typically more than 500 μm). It may be. An extensible pressure-sensitive adhesive sheet having such a total thickness can be preferably used, for example, for being attached to a wall surface or the like, and after being used for a predetermined period of time, fixing an object to be replaced.

<Characteristics of extensible adhesive sheet>
The extensible pressure-sensitive adhesive sheet disclosed herein preferably exhibits a shear adhesive strength of 0.5 MPa or more. Thereby, the extensible pressure-sensitive adhesive sheet adheres well to the adherend. Since the extensible pressure-sensitive adhesive sheet exhibiting the above-mentioned adhesive force shows a strong stress against a force for shifting the adhesive interface (that is, a shear force), a highly reliable bonding means in a use mode exposed to the shear force Can be More preferably, the shear adhesive strength is 0.8 MPa or more (for example, 1.0 MPa or more, typically 1.2 MPa or more). The upper limit of the shear adhesive strength is not particularly limited. However, if the shear adhesive strength is too high, the tensile removability and the adhesive residue preventing property tend to decrease, so that the shear adhesive strength is 5 MPa or less (for example, 3 MPa or less, typically 1.MPa). 5 MPa or less).

  The measurement of the shear adhesive strength can be performed by the method described below. An extensible pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) is cut into a size of 20 mm × 20 mm to prepare a measurement sample. In an environment of 23 ° C. and 50% RH, each adhesive surface of the above-mentioned measurement sample is overlapped on the surface of two stainless steel plates, respectively, and a 2 kg roller is reciprocated once and pressed. After leaving it for 30 minutes in the same environment, the shear adhesive strength [MPa] is measured using a tensile tester under the conditions of a tensile speed of 300 mm / min and a peel angle of 0 °. Specifically, as shown in FIG. 9, one adhesive surface 800A of the measurement sample 800 is attached to a stainless steel plate 801 and the other adhesive surface 800B of the measurement sample 800 is attached to a stainless steel plate 802 and pressed. This is pulled at the above-mentioned speed in the direction of the arrow in FIG. 9 (that is, in the shearing direction), and the peel strength per 20 mm × 20 mm is measured. The shear adhesive strength [MPa] is determined from the obtained value. As the tensile tester, a universal tensile / compression tester (product name “TG-1kN”, manufactured by Minebea) can be used.

  The stretchable pressure-sensitive adhesive sheet disclosed herein preferably has an initial pressure A on PC (polycarbonate) of 3 N / 20 mm or more. Thereby, it is possible to preferably exhibit a sufficient adhesive function to an adherend formed from various materials such as PC. Further, when the stretchable pressure-sensitive adhesive sheet having the initial adhesive force A is used, for example, in a portable electronic device, the fixed arrangement of the adhered member can be maintained even when the portable electronic device falls. The initial adhesive force A is more preferably 5 N / 20 mm or more (for example, 6 N / 20 mm or more, typically 6.5 N / 20 mm or more). The upper limit of the initial adhesive force A is not particularly limited, but may be less than 15 N / 20 mm (for example, less than 12 N / 20 mm, typically less than 10 N / 20 mm) in consideration of the pull-off property and the adhesive residue prevention property. preferable.

  The measurement of the initial adhesive strength A can be performed by the following method. An extensible pressure-sensitive adhesive sheet cut to a size of 20 mm in width and 100 mm in length is prepared. In an environment of 23 ° C. and 50% RH, the adhesive surface of the adhesive sheet (double-sided adhesive sheet) is exposed, and the adhesive surface is pressed against the surface of the PC board by reciprocating a 2 kg roller once. After leaving it for 30 minutes in the same environment, the peel strength [N / 20 mm width] under the conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees using a tensile tester according to JIS Z 0237: 2000. Is measured. In addition, after bonding a 25-micrometer-thick polyethylene terephthalate (PET) film to the other adhesive surface of the double-sided adhesive sheet, the measurement may be performed by pressing the adhesive surface to be measured to a PC plate. As the tensile tester, a universal tensile / compression tester (product name “TG-1kN”, manufactured by Minebea) can be used.

  In the extensible pressure-sensitive adhesive sheet disclosed herein, it is preferable that the tensile peeling stress B for PC is 22 N / 20 mm or less. This makes it possible to more smoothly remove the extensible pressure-sensitive adhesive sheet from the adherend when the extensible pressure-sensitive adhesive sheet is pulled from the adherend in the pull-peeling direction. The tensile peeling stress B is more preferably 20 N / 20 mm or less (for example, 19 N / 20 mm or less, typically 18 N / 20 mm or less). Although the lower limit of the tensile peeling stress B is not particularly limited, it is appropriate to be about 5 N / 20 mm or more (for example, 8 N / 20 mm or more, typically 10 N / 20 mm or more) from the relationship with the initial adhesive strength A. .

  The measurement of the tensile peeling stress B can be performed by the following method. The extensible pressure-sensitive adhesive sheet is cut into a size of 20 mm in width and 120 mm in length to prepare a measurement sample. Under an environment of 23 ° C. and 50% RH, each adhesive surface of the above-mentioned measurement sample (double-sided adhesive sheet) is superimposed on the surface of two PC boards (30 mm × 100 mm × 2 mm thick), and a 2 kg roller makes one round trip. And crimped. A 70 mm portion (that is, 20 mm × 70 mm) from one end in the longitudinal direction of the measurement sample is pressure-bonded to each PC board. After leaving this for 30 minutes in the same environment, the two PC boards were fixed using a tensile tester, and the peel strength [N / 20 mm width] under the conditions of a tensile speed of 300 mm / min and a peel angle of 0 °. ] Is measured. Specifically, as shown in FIG. 10, each of the adhesive surfaces 800A and 800B of the extensible adhesive sheet measurement sample 800 is bonded to two PC boards 811 and 812, respectively, and pressed. This is pulled at the above-mentioned speed in the direction of the arrow in FIG. 10 (that is, in the direction of tensile peeling), and the peel strength [N / 20 mm width] is measured. As the tensile tester, a universal tensile / compression tester (product name “TG-1kN”, manufactured by Minebea) can be used.

  In a preferred embodiment, the ratio (B / A) of the tensile peeling stress B [N / 20 mm] to the initial adhesive strength A [N / 20 mm] is 3.0 or less. Thereby, it is possible to preferably achieve both a sufficient adhesive function at the time of use and excellent tensile removability at the time of removal. The ratio (B / A) is preferably 2.8 or less (for example, 2.6 or less, typically 2.4 or less). Ideally, the ratio (B / A) should be as low as possible, but in practice, the lower limit may be, for example, about 1.2 or more (typically 1.5 or more).

  In a preferred embodiment, the extensible pressure-sensitive adhesive sheet has a breaking strength of 10 MPa or more. Thereby, for example, in a configuration showing an adhesive strength equal to or higher than a predetermined value, a configuration in which damage such as breakage or the like occurs when the extensible adhesive sheet is removed can be obtained. Also, it tends to have excellent workability. The breaking strength is more preferably 20 MPa or more, and still more preferably 30 MPa or more (for example, 45 MPa or more, typically 60 MPa or more). From the viewpoint of the elasticity and extensibility of the extensible pressure-sensitive adhesive sheet, the breaking strength is preferably about 100 MPa or less (for example, 80 MPa or less, typically 70 MPa or less).

  The breaking strength is measured according to the method for measuring “tensile strength” described in JIS K 7311: 1995. More specifically, the breaking strength can be measured using a No. 3 dumbbell-shaped test piece (5 mm in width) at a tensile speed of 300 mm / min. As the tensile tester, a product name “Autograph AG-10G type tensile tester” manufactured by Shimadzu Corporation can be used. At the time of the test, it is preferable to apply a powder on the adhesive surface to remove the influence of the stickiness of the adhesive. The tensile direction in the above test is not particularly limited, but when the extensible pressure-sensitive adhesive sheet is long, it is preferable to match the longitudinal direction. The breaking strength can be adjusted, for example, by selecting a base material.

  In a preferred embodiment, the tensile strength [MPa] of the extensible pressure-sensitive adhesive sheet is 5 times or more (eg, 10 times or more, typically 30 times or more) of the shear adhesive strength [MPa]. Thereby, when the extensible pressure-sensitive adhesive sheet is pulled and removed, damage such as breakage can be more reliably prevented.

  The extensible pressure-sensitive adhesive sheet disclosed herein preferably has an elongation at break of 300% or more. Thereby, the tension and the deformation of the extensible pressure-sensitive adhesive sheet interact with each other, and excellent tensile removability (particularly, shear removability) is realized. The elongation at break is more preferably 500% or more (for example, 700% or more, typically 800% or more). The upper limit of the elongation at break is not particularly limited, but may be, for example, about 1000% or less (typically 900% or less) from the viewpoint of removal workability and the like.

  The elongation at break is measured according to the measuring method of “elongation” described in JIS K 7311: 1995. More specifically, the elongation at break can be measured using a No. 3 dumbbell-shaped test piece (width 5 mm, mark interval 20 mm) under the condition of a tensile speed of 300 mm / min. The tensile tester and others are basically the same as in the case of the breaking strength described above. The tensile direction in the above test is not particularly limited, but when the extensible pressure-sensitive adhesive sheet is long, it is preferable to match the longitudinal direction. The elongation at break can be adjusted, for example, by selecting a base material.

  The extensible pressure-sensitive adhesive sheet disclosed herein preferably exhibits a 100% modulus of less than 10 MPa. By setting the 100% modulus of the extensible pressure-sensitive adhesive sheet to be less than the predetermined value, when the extensible pressure-sensitive adhesive sheet is pulled from the adherend by elongating and deforming, the resistance at the start of pulling becomes small and the tensile removability is excellent. Tend. The 100% modulus is more preferably less than 5 MPa. Although the lower limit of the 100% modulus is not particularly limited, it is usually suitable to be 0.5 MPa or more (for example, 1 MPa or more) from the viewpoint of the workability of sticking the extensible pressure-sensitive adhesive sheet.

  The 100% modulus is measured according to the method for measuring “tensile stress” described in JIS K 7311: 1995. More specifically, using a No. 3 dumbbell-shaped test piece (width 5 mm, mark interval 20 mm), the sample was pulled at a tensile speed of 300 mm / min, and the stress [MPa when the mark length was increased by 100%. ] Is set to 100% modulus. As the tensile tester, a product name “Autograph AG-10G type tensile tester” manufactured by Shimadzu Corporation can be used. The 100% modulus of the pressure-sensitive adhesive sheet can be adjusted, for example, by selecting the type of the base material (selection of the mixing ratio of the hard component and the soft component, etc.), the molding method, and the like.

  In one preferred embodiment, the extensible pressure-sensitive adhesive sheet suitably exhibits a tensile recovery of more than 50%. The tensile recovery rate is more preferably 70% or more. The tensile recovery is more preferably 80% or more (for example, 90% or more, typically 93% to 100%). Thereby, damage such as breakage during removal of the extensible pressure-sensitive adhesive sheet can be prevented to a higher degree. This will be described. For example, when removing the extensible pressure-sensitive adhesive sheet by pulling it in the shearing direction, it usually takes some time depending on the adhesion area and the like. Therefore, the removal operation may be interrupted on the way. In such a case, if the tensile recovery rate of the extensible pressure-sensitive adhesive sheet is equal to or less than a predetermined value, the removal operation is restarted from a state in which the mechanical properties (strength, elasticity, etc.) are reduced due to the tension before the interruption of the operation. obtain. At that time, the extensible pressure-sensitive adhesive sheet cannot withstand the tension at the time of resuming the removing operation, and is likely to be damaged such as being cut off. The extensible pressure-sensitive adhesive sheet exhibiting the above-mentioned tensile recovery rate, even when it is removed in such a manner as to be interrupted once as described above, the reduction in mechanical properties is suppressed by the recovery after pulling, so that the damage is reduced. It can be more highly prevented.

The measurement of the tensile recovery rate is performed by the following method.
[Measurement of tensile recovery rate]
Per extensible adhesive sheet, performing a tensile test stretching specific section distance L ₀ of the adhesive sheet 100%. After stretching the pressure-sensitive adhesive sheet of 100%, the length of the specific section is taken as _{L 1} after the lapse of 5 minutes to release the formula: tensile recovery ratio _{(%) = L 0 / L} 1 × 100; from Determine the tensile recovery rate.
More specifically, in accordance with JIS K 7311: 1995, 100% elongation is performed using a No. 3 dumbbell-shaped test piece (width: 5 mm, mark interval: 20 mm) at a tensile speed of 300 mm / min. In other words, it is pulled until the mark line interval is extended by 20 mm. Then, the length L ₁ (marked line interval: mm) after 5 minutes from the release from the tension is measured, and the tension recovery rate is calculated from the formula: tensile recovery rate (%) = L ₀ / L ₁ × 100; . In this method, L ₀ is the initial mark line spacing of 20 mm. The tensile tester and others are basically the same as in the case of the elongation at break described above. Although the tensile direction in the above test is not particularly limited, it is preferable that the tensile direction coincides with the longitudinal direction of the extensible pressure-sensitive adhesive sheet or a long portion thereof. The tensile recovery rate can be adjusted, for example, by selecting a base material.

<Adhesive layer>
(Base polymer)
The pressure-sensitive adhesive layer disclosed herein (in the case of a double-sided pressure-sensitive adhesive sheet with a substrate, includes the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer; the same applies hereinafter) is a known acrylic polymer in the field of pressure-sensitive adhesives. Containing, as a base polymer, one or more of various rubber-like polymers such as rubber-based polymers, polyester-based polymers, urethane-based polymers, polyether-based polymers, silicone-based polymers, polyamide-based polymers, and fluorine-based polymers. obtain. As will be described in detail later, the pressure-sensitive adhesive layer disclosed herein is preferably an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer, a rubber-based pressure-sensitive adhesive layer containing a rubber-based polymer as a base polymer, or a urethane-based polymer. Is a urethane-based pressure-sensitive adhesive layer containing as a base polymer. Alternatively, a pressure-sensitive adhesive layer using an acrylic polymer and a rubber polymer in combination as a base polymer may be used.

(Acrylic polymer)
In a preferred embodiment, the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer from the viewpoints of pressure-sensitive properties (typically, adhesive strength), molecular design, and stability over time. In this specification, the “base polymer” of the pressure-sensitive adhesive refers to a main component of a polymer component contained in the pressure-sensitive adhesive (typically, a component contained in an amount exceeding 50% by weight).

  As the acrylic polymer, for example, a polymer of a monomer raw material which contains an alkyl (meth) acrylate as a main monomer and may further contain a sub-monomer having copolymerizability with the main monomer is preferable. Here, the main monomer refers to a component that accounts for more than 50% by weight of all monomer components in the monomer raw material.

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be suitably used.
CH ₂ ＣC (R ¹ ) COOR ² (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. R ² is a linear alkyl group having 1 to 20 carbon atoms (hereinafter, such a range of the number of carbon atoms may be referred to as “C _1-20 ”). From the viewpoint of the storage elastic modulus of the pressure-sensitive adhesive and the like, an alkyl (meth) acrylate in which R ² is a C _1-14 (for example, C _2-10 , typically C _4-8 ) chain alkyl group is preferable. ^An alkyl acrylate wherein ¹ is a hydrogen atom and R ² is a C _4-8 chain alkyl group is more preferred.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 chain alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl. (Meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate Octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) Acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, Eicosyl (meth) acrylate and the like. These alkyl (meth) acrylates can be used alone or in combination of two or more. Preferred alkyl (meth) acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). BA is more preferred from the viewpoints of adhesive properties and prevention of adhesive residue.

The proportion of the main monomer in all the monomer components is preferably 70% by weight or more (for example, 85% by weight or more, typically 90% by weight or more). The upper limit of the mixing ratio of the main monomer is not particularly limited, but is preferably 99.5% by weight or less (for example, 99% by weight or less). When C _4-8 alkyl acrylate is used as the monomer component, the proportion of C _4-8 alkyl acrylate in the alkyl (meth) acrylate contained in the monomer component is preferably 70% by weight or more, The content is more preferably 90% by weight or more, even more preferably 95% by weight or more (typically 99 to 100% by weight). The technology disclosed herein can be preferably implemented in an embodiment in which 50% by weight or more (for example, 60% by weight or more) of all monomer components is BA. In a preferred embodiment, the total monomer component may further comprise 2EHA in a lower proportion than BA.

  The auxiliary monomer having copolymerizability with the main monomer, alkyl (meth) acrylate, can be useful for introducing a crosslinking point into the acrylic polymer or increasing the cohesive strength of the acrylic polymer. As the auxiliary monomer, for example, a carboxy group-containing monomer, a hydroxyl group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, a keto group-containing monomer, a monomer having a nitrogen atom-containing ring, an alkoxysilyl group-containing monomer, One or more functional group-containing monomers such as an imide group-containing monomer and an epoxy group-containing monomer can be used. For example, from the viewpoint of improving cohesive strength, an acrylic polymer obtained by copolymerizing a carboxy group-containing monomer and / or a hydroxyl group-containing monomer as the above-mentioned auxiliary monomer is preferable. Preferred examples of the carboxy group-containing monomer include acrylic acid (AA) and methacrylic acid (MAA). Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth). Examples include hydroxyalkyl (meth) acrylates such as acrylates and unsaturated alcohols. Among them, hydroxyalkyl (meth) acrylate is preferred, and 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA) are more preferred.

  The amount of the auxiliary monomer may be appropriately selected so as to achieve a desired cohesive force, and is not particularly limited. Normally, from the viewpoint of achieving a good balance between the adhesive force and the cohesive force, the amount of the auxiliary monomer is suitably 0.5% by weight or more, and preferably 1% by weight, of all the monomer components of the acrylic polymer. % Or more. Further, the amount of the auxiliary monomer is suitably 30% by weight or less, preferably 10% by weight or less (for example, 5% by weight or less) in all the monomer components. When the carboxy group-containing monomer is copolymerized with the acrylic polymer, the content of the carboxy group-containing monomer is determined from the viewpoint of compatibility between the adhesive force and the cohesive force in all the monomer components used for the synthesis of the acrylic polymer. It is preferably about 0.1% by weight or more (eg, 0.2% by weight or more, typically 0.5% by weight or more), and about 10% by weight or less (eg, 8% by weight or less, typically 5% by weight or less). % By weight or less). When the hydroxyl group-containing monomer is copolymerized with the acrylic polymer, the content of the hydroxyl group-containing monomer is set to about 0 in all the monomer components used for the synthesis of the acrylic polymer from the viewpoint of compatibility between the adhesive force and the cohesive force. 0.001% by weight or more (eg, 0.01% by weight or more, typically 0.02% by weight or more), and is preferably about 10% by weight or less (eg, 5% by weight or less, typically 2% by weight). The following is preferred.

  In the acrylic polymer disclosed herein, a monomer (other monomer) other than the above may be copolymerized as long as the effects of the present invention are not significantly impaired. These other monomers can be used for the purpose of adjusting the glass transition temperature of the acrylic polymer, adjusting the adhesive performance (for example, peelability), and the like. For example, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl esters, aromatic vinyl compounds and the like can be mentioned as monomers capable of improving the cohesive strength of the adhesive. These other monomers may be used alone or in a combination of two or more. Among them, vinyl esters are preferred. Specific examples of vinyl esters include vinyl acetate (VAc), vinyl propionate, and vinyl laurate. Among them, VAc is preferable. The content of the other monomer is about 30% by weight or less (typically 0.01 to 30% by weight, for example, 0.1 to 10% by weight) in all the monomer components used for the synthesis of the acrylic polymer. Is preferred.

  The copolymer composition of the acrylic polymer is adjusted so that the glass transition temperature (Tg) of the polymer is −15 ° C. or less (typically −70 ° C. or more and −15 ° C. or less) from the viewpoint of impact resistance and the like. It is suitably designed, and the temperature is preferably −25 ° C. or less (eg, −60 ° C. or more and −25 ° C. or less), more preferably −40 ° C. or less (eg, −60 ° C. or more and −40 ° C. or less).

The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the type and amount ratio of the monomers used for synthesizing the polymer). Here, the Tg of the acrylic polymer refers to the Fox based on the Tg of the homopolymer (homopolymer) of each monomer constituting the polymer and the weight fraction (copolymerization ratio on a weight basis) of the monomer. Means the value obtained from the equation. The Fox equation is a relational expression between the Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer, as shown below.
1 / Tg = Σ (Wi / Tgi)
In the above Fox equation, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (weight-based copolymerization ratio), and Tgi is the Represents the glass transition temperature (unit: K) of the homopolymer. As the Tg of the homopolymer, a value described in a known document is adopted.

In the technology disclosed herein, the following values are specifically used as the Tg of the homopolymer.
2-ethylhexyl acrylate -70 ° C
Butyl acrylate -55 ° C
Vinyl acetate 32 ° C
Acrylic acid 106 ° C
Methacrylic acid 228 ° C
2-hydroxyethyl acrylate -15 ° C
4-hydroxybutyl acrylate -40 ° C
For the Tg of the homopolymer other than those exemplified above, the values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) are used. If not described in the above Polymer Handbook, the value obtained by the measurement method described in JP-A-2007-51271 shall be used.

  The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthetic methods for the acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method, are appropriately adopted. be able to. For example, a solution polymerization method can be preferably used. As a monomer supply method at the time of performing the solution polymerization, a batch supply method, a continuous supply (dropping) method, a divided supply (dropping) method, or the like that supplies all the monomer materials at once can be appropriately adopted. The polymerization temperature can be appropriately selected according to the type of the monomer and the solvent to be used, the type of the polymerization initiator, and the like, and can be, for example, about 20 ° C. or more (typically, 40 ° C. or more), for example, about 170 ° C. ° C or lower (typically 140 ° C or lower). Alternatively, photopolymerization performed by irradiating light such as UV (typically performed in the presence of a photopolymerization initiator) or radiation polymerization performed by irradiating radiation such as β-rays or γ-rays Active energy ray irradiation polymerization may be employed.

  The solvent (polymerization solvent) used for the solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds (typically, aromatic hydrocarbons) such as toluene, acetates such as ethyl acetate, and aliphatic or alicyclic hydrocarbons are preferably used.

  The initiator used for the polymerization can be appropriately selected from conventionally known polymerization initiators according to the type of the polymerization method. For example, one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. Other examples of the polymerization initiator include persulfates such as potassium persulfate; peroxide initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane initiators such as phenyl-substituted ethane; aromatic carbonyl compounds And the like. Still another example of the polymerization initiator includes a redox initiator obtained by combining a peroxide and a reducing agent. Such polymerization initiators can be used alone or in combination of two or more. The amount of the polymerization initiator used may be a usual amount, for example, about 0.005 to 1 part by weight (typically 0.01 to 1 part by weight) based on 100 parts by weight of all monomer components. You can choose from a range.

The weight average molecular weight (Mw) of the base polymer (preferably an acrylic polymer) disclosed herein is not particularly limited, and may be, for example, in the range of 10 × 10 ⁴ or more and 500 × 10 ⁴ or less. From the viewpoint of balancing the cohesive force and the adhesive force at a high level, the Mw of the base polymer (preferably an acrylic polymer) is preferably 10 × 10 ⁴ or more, more preferably 20 × 10 ⁴ or more (for example, 20 × 10 ⁴ or more). ⁴ or more), more preferably 35 × 10 ⁴ or more (eg, 35 × 10 ⁴ or more), preferably 150 × 10 ⁴ or less, more preferably 110 × 10 ⁴ or less (eg, 75 × 10 ⁴ or less), and still more preferably Is 90 × 10 ⁴ or less (for example, 65 × 10 ⁴ or less). Here, Mw refers to a value in terms of standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC device, for example, a model name “HLC-8320GPC” (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) may be used.

(Rubber-based polymer)
In another preferred embodiment, the pressure-sensitive adhesive layer is made of a rubber-based pressure-sensitive adhesive. The rubber pressure-sensitive adhesive according to a further preferred embodiment contains, as a base polymer, a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. The monovinyl-substituted aromatic compound refers to a compound in which one functional group having a vinyl group is bonded to an aromatic ring. Representative examples of the aromatic ring include a benzene ring (which may be a benzene ring substituted with a functional group having no vinyl group (eg, an alkyl group)). Specific examples of the above-mentioned monovinyl-substituted aromatic compound include styrene, α-methylstyrene, vinyltoluene, vinylxylene and the like. Specific examples of the conjugated diene compound include 1,3-butadiene and isoprene. Such a block copolymer can be used alone or in combination of two or more as a base polymer.

  The A segment (hard segment) in the block copolymer has a copolymerization ratio of the monovinyl-substituted aromatic compound (two or more types can be used in combination) of 70% by weight or more (more preferably 90% by weight or more). May be substantially 100% by weight). The B segment (soft segment) in the block copolymer has a copolymerization ratio of the conjugated diene compound (two or more types can be used in combination) of 70% by weight or more (more preferably 90% by weight or more, and May be 100% by weight.) According to such a block copolymer, a higher-performance pressure-sensitive adhesive sheet can be realized.

  The block copolymer may be in the form of a diblock, a triblock, a radial, a mixture thereof, and the like. In the triblock body and the radial body, it is preferable that an A segment (for example, a styrene block) is arranged at the terminal of the polymer chain. This is because the A segments disposed at the ends of the polymer chain easily aggregate to form a domain, thereby forming a pseudo cross-linked structure and improving the cohesiveness of the pressure-sensitive adhesive. The block copolymer in the technology disclosed herein has, for example, a diblock ratio of 30% by weight or more (more preferably 40% by weight) from the viewpoint of adhesion (peeling strength) to an adherend and repulsion resistance. Above, more preferably 50% by weight or more, particularly preferably 60% by weight or more, typically 65% by weight or more, for example, 70% by weight or more can be preferably used. In addition, from the viewpoint of resistance to a continuously applied stress, those having a diblock ratio of 90% by weight or less (more preferably 85% by weight or less, for example, 80% by weight or less) can be preferably used. For example, it is preferable to use a block copolymer having a diblock ratio of 60 to 85% by weight.

(Styrene block copolymer)
In a preferred embodiment of the technology disclosed herein, the base polymer is a styrenic block copolymer. For example, it can be preferably carried out in a mode in which the base polymer contains at least one of a styrene isoprene block copolymer and a styrene butadiene block copolymer. In the styrene-based block copolymer contained in the adhesive, the proportion of the styrene isoprene block copolymer is 70% by weight or more, the proportion of the styrene-butadiene block copolymer is 70% by weight or more, or styrene. It is preferable that the total ratio of the isoprene block copolymer and the styrene butadiene block copolymer is 70% by weight or more. In a preferred embodiment, substantially all (for example, 95 to 100% by weight) of the styrene-based block copolymer is a styrene-isoprene block copolymer. In another preferred embodiment, substantially all (for example, 95 to 100% by weight) of the styrene-based block copolymer is a styrene-butadiene block copolymer. According to such a composition, a pressure-sensitive adhesive sheet excellent in repulsion resistance and well-balanced with other pressure-sensitive adhesive properties can be suitably realized.

  The styrenic block copolymer may be in the form of a diblock, a triblock, a radial, a mixture thereof, or the like. In the triblock body and the radial body, it is preferable that a styrene block is disposed at the terminal of the polymer chain. The reason is that the styrene blocks arranged at the ends of the polymer chains easily aggregate to form a styrene domain, thereby forming a pseudo-crosslinked structure and improving the cohesiveness of the pressure-sensitive adhesive. The styrene-based block copolymer used in the technology disclosed herein has, for example, a diblock ratio of 30% by weight or more (more preferably) from the viewpoint of adhesion (peeling strength) to an adherend and resistance to repulsion. Is preferably 40% by weight or more, more preferably 50% by weight or more, particularly preferably 60% by weight or more, and typically 65% by weight or more. A styrene-based block copolymer having a diblock ratio of 70% by weight or more (for example, 75% by weight or more) may be used. From the viewpoint of holding power and the like, a styrene block copolymer having a diblock ratio of 90% by weight or less (more preferably, 85% by weight or less, for example, 80% by weight or less) can be preferably used. For example, a styrene block copolymer having a diblock ratio of 60 to 85% by weight can be preferably used.

  The styrene content of the styrenic block copolymer may be, for example, 5 to 40% by weight. From the viewpoint of repulsion resistance and holding power, a styrene-based block copolymer having a styrene content of 10% by weight or more (more preferably, more than 10% by weight, for example, 12% by weight or more) is usually preferable. Further, from the viewpoint of the adhesive strength to the adherend, a styrene-based block copolymer having a styrene content of 35% by weight or less (typically 30% by weight or less, more preferably 25% by weight or less, for example, less than 20% by weight) is used. Coalescence is preferred. For example, a styrene-based block copolymer having a styrene content of 12% by weight or more and less than 20% by weight can be preferably used.

(Urethane polymer)
In still another preferred embodiment, the pressure-sensitive adhesive layer is formed of a urethane-based pressure-sensitive adhesive. Here, the urethane-based pressure-sensitive adhesive (layer) refers to a pressure-sensitive adhesive (layer) containing a urethane-based polymer as a base polymer. The urethane-based pressure-sensitive adhesive is typically made of a urethane-based resin containing, as a base polymer, a urethane-based polymer obtained by reacting a polyol with a polyisocyanate compound. The urethane-based polymer is not particularly limited, and a suitable urethane-based polymer (ether-based polyurethane, ester-based polyurethane, carbonate-based polyurethane, or the like) that can function as an adhesive can be used. Examples of the polyol include polyether polyol, polyester polyol, polycarbonate polyol, and polycaprolactone polyol. Examples of the polyisocyanate compound include diphenylmethane diisocyanate, tolylene diisocyanate, and hexamethylene diisocyanate.

(Filler particles)
The pressure-sensitive adhesive layer disclosed herein preferably contains filler particles. Thereby, it is possible to preferably achieve both the maintenance of the initial adhesive force A and the reduction of the tensile peeling stress B. This will be described. The filler particles contained in the pressure-sensitive adhesive layer may be in a state of being exposed on the pressure-sensitive adhesive surface or in a state of being included in the pressure-sensitive adhesive layer. The filler particles exposed on the pressure-sensitive adhesive surface reduce the pressure-sensitive adhesive area on the pressure-sensitive adhesive surface and improve the slip property of the bonding interface in the shear direction. As a result, the tensile peeling stress B is reduced, but the decrease in the pressure-sensitive adhesive area on the pressure-sensitive adhesive surface also results in a decrease in the initial adhesive force A. On the other hand, the filler particles existing inside the pressure-sensitive adhesive layer are considered to greatly contribute to the reduction of the tensile peeling stress B without lowering the initial adhesive force A. Although the main reason is not to be construed as being particularly limited, a change in the state of the pressure-sensitive adhesive layer due to deformation of the pressure-sensitive adhesive sheet may be considered. Specifically, since the tension peeling is a mode in which the pressure-sensitive adhesive is peeled off in a direction parallel to the adhesive surface (a tensile peeling direction; also referred to as a shearing direction), the pressure-sensitive adhesive sheet is deformed in this direction during the tensile peeling. . The extensible pressure-sensitive adhesive sheet expands in response to the above-mentioned tension, and the pressure-sensitive adhesive layer is deformed accordingly. For example, when the film-like substrate supporting the pressure-sensitive adhesive layer has extensibility with respect to tension, the pressure-sensitive adhesive layer is greatly deformed as the substrate elongates. It is considered that the deformation of the pressure-sensitive adhesive layer increases the amount of filler particles contained in the pressure-sensitive adhesive layer exposed to the pressure-sensitive adhesive surface, and improves the slip property in the shear direction at the bonding interface. It is also considered that the pressure-sensitive adhesive (adhesive component) in the pressure-sensitive adhesive layer is deformed by tensile peeling, whereas the filler particles behave differently from the pressure-sensitive adhesive in the pressure-sensitive adhesive layer. It is also conceivable that the difference in the behavior of the pressure-sensitive adhesive and the filler particles with respect to the tensile peeling contributes to the reduction of the tensile peeling stress. The change in the surface state of the pressure-sensitive adhesive layer and the behavior of the constituent components of the pressure-sensitive adhesive layer are considered to be negligible or not negligible in, for example, 90-degree peeling or 180-degree peeling due to the difference in the peeling mode. Can be However, it is considered that it typically has a large effect on the stress change during tensile peeling. As a result, the filler particles contained in the pressure-sensitive adhesive layer are considered to greatly contribute to both maintaining the initial adhesive force A and reducing the tensile peeling stress B. The effect of containing filler particles is particularly noticeable in an extensible pressure-sensitive adhesive sheet. Further, in an extensible pressure-sensitive adhesive sheet having a substrate, typically, the mechanical properties of the substrate can greatly contribute to the adhesive strength (typically, 180-degree peel strength). It is considered that the contribution of the additive component such as an agent or a crosslinking agent) to the adhesive strength is relatively small. In such a pressure-sensitive adhesive sheet, by including filler particles in the pressure-sensitive adhesive layer, an action of selectively reducing only the tensile peeling stress B while maintaining the initial pressure-sensitive adhesive strength A is preferably realized.

  The type of filler particles used is not particularly limited. For example, a particulate or fibrous filler can be used. The constituent materials of the filler particles (typically, particulate fillers) include, for example, metals such as copper, silver, gold, platinum, nickel, aluminum, chromium, iron, and stainless steel; aluminum oxide, silicon oxide (silicon dioxide), and oxide. Metal oxides such as titanium, zirconium oxide, zinc oxide, tin oxide, copper oxide and nickel oxide; aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, zinc hydroxide, silicic acid, iron hydroxide, copper hydroxide, Metal hydroxides and hydrated metal compounds such as barium hydroxide, zirconium oxide hydrate, tin oxide hydrate, basic magnesium carbonate, hydrotalcite, dawsonite, borax, zinc borate; silicon carbide, boron carbide, Carbides such as nitrogen carbide and calcium carbide; nitrides such as aluminum nitride, silicon nitride, boron nitride and gallium nitride Carbonates such as calcium carbonate; titanates such as barium titanate and potassium titanate; carbon-based substances such as carbon black, carbon tubes (carbon nanotubes), carbon fibers and diamonds; inorganic materials such as glass; Acrylic resin (for example, polymethyl methacrylate), phenol resin, benzoguanamine resin, urea resin, silicone resin, polyester, polyurethane, polyethylene, polypropylene, polyamide (for example, nylon), polyimide, and polymers such as polyvinylidene chloride; Alternatively, natural raw material particles such as volcanic shirasu, clay, and sand may be used. Various synthetic fiber materials and natural fiber materials can be used as the fibrous filler. These can be used alone or in combination of two or more. Among them, a particulate filler is preferable from the viewpoint of reducing the tensile peeling stress, and among them, the use of a particulate filler composed of an inorganic material (for example, aluminum hydroxide) is preferable.

  When the pressure-sensitive adhesive layer contains filler particles, it is preferable that 50% by weight or more of the filler particles contained in the pressure-sensitive adhesive layer have a particle diameter smaller than the thickness of the pressure-sensitive adhesive layer. As a result, the adhesive surface is more likely to maintain a favorable surface state, and can exhibit desired adhesive properties (for example, initial adhesive strength A). In addition, the appearance of the surface of the pressure-sensitive adhesive layer is more likely to be favorably maintained. In a preferred embodiment, 60% by weight or more (for example, 70% by weight or more, typically 80% by weight or more) of the filler particles contained in the pressure-sensitive adhesive layer has a particle diameter smaller than the thickness of the pressure-sensitive adhesive layer. . It is more preferable that substantially all of the filler particles (typically 99 to 100% by weight) contained in the pressure-sensitive adhesive layer have a particle diameter smaller than the thickness of the pressure-sensitive adhesive layer. In another preferred embodiment, from the viewpoint of improving the surface condition of the pressure-sensitive adhesive surface, 40% by weight or more (for example, 50% by weight or more, typically 55% by weight or more) of the filler particles contained in the pressure-sensitive adhesive layer. Has a particle size smaller than 2/3 (i.e., 2 / 3T, more preferably 1/2, i.e., 1 / 2T) of the thickness T of the pressure-sensitive adhesive layer. It should be noted that X weight% or more of the filler particles has a particle size smaller than Y means that the cumulative particle size (weight basis) up to the particle size Y (μm) in the particle size distribution obtained by the measurement based on the sieving method is X ( % By weight). The ratio (% by weight) of the filler particles having a predetermined particle size can be determined based on the particle size distribution.

  In one preferred embodiment, particles having a particle diameter of less than 30 μm account for 50% by weight or more (eg, 70% by weight or more, typically 90% by weight or more) of the filler particles contained in the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer containing such filler particles does not easily impair the smoothness of the pressure-sensitive adhesive surface even if the content of the filler particles is relatively large, and is advantageous in terms of maintaining the adhesive force and appearance. As for the filler particles contained in the pressure-sensitive adhesive layer, particles having a particle size of less than 20 μm (eg, less than 15 μm, typically less than 10 μm) are 50% by weight or more (eg, 70% by weight or more, typically 80% by weight or more). More preferably.

  In a preferred embodiment, the proportion of particles having a particle diameter of less than 1 μm among the filler particles contained in the pressure-sensitive adhesive layer is 50% by weight or less. From the viewpoint of reducing the tensile peeling stress, it is desirable that the particle size of the filler particles has a certain size. It is preferable in terms of productivity that the amount of the fine particles is limited, for example, an excessive increase in viscosity does not occur in the preparation of the pressure-sensitive adhesive composition. The proportion of particles having a particle size of less than 1 μm (eg, less than 2 μm, typically less than 5 μm) in the filler particles contained in the pressure-sensitive adhesive layer is 30% by weight or less (eg, 10% by weight or less, typically 5% by weight or less).

  The average particle size of the entire filler particles contained in the pressure-sensitive adhesive layer is usually 0.5 μm or more, and preferably 0.8 μm or more (for example, 3 μm or more, typically 5 μm or more). When the average particle size increases, the effect of reducing the tensile peeling stress tends to be improved, and the tensile peeling stress B can be efficiently reduced by adding a small amount of filler particles. It is also preferable that the average particle size is not less than a predetermined value, from the viewpoint of maintaining the viscosity and the dispersibility of the composition well. The upper limit of the average particle size is usually appropriate to be 50 μm or less, preferably 30 μm or less, more preferably 25 μm or less, and still more preferably 15 μm or less. When the average particle size is small, a decrease in adhesive performance tends to be suppressed. It is desirable that the average particle size is also small in terms of the appearance of the adhesive surface. In this specification, the average particle size of the filler particles refers to a particle size (50% median diameter) at which the weight-based cumulative particle size becomes 50% in a particle size distribution obtained by measurement based on a sieving method. .

  The shape of the filler particles is not particularly limited, and may be, for example, a bulk shape, a needle shape, a plate shape (for example, a hexagonal plate shape), a layer shape, or the like. The concept of a bulk shape includes, for example, a spherical shape, a rectangular parallelepiped shape, a crushed shape, or an irregular shape thereof. The shape of the filler particles is preferably a bulk shape, and among them, a spherical shape is more preferable.

  The average aspect ratio of the filler particles is not particularly limited, and is preferably about less than 100, preferably less than 50, more preferably less than 10 (eg, less than 5, typically less than 2) from the viewpoint of reducing tensile peel stress. Can be Here, the average aspect ratio of the filler particles is determined as the average value of the aspect ratio of each particle represented by the major axis / minor axis of the filler particles. The major axis typically refers to the maximum passing length of the particles to be measured, and the minor axis typically refers to the minimum passing length of the particles to be measured. The average aspect ratio can be determined through observation with a transmission electron microscope.

When the pressure-sensitive adhesive layer contains filler particles, the content C of the filler particles in the pressure-sensitive adhesive layer is suitably set to 30% by volume or less. By appropriately adjusting the particle diameter and the content of the filler particles, it is possible to preferably reduce the tensile peeling stress B while suppressing a decrease in the initial adhesive force A. The content C of the filler particles in the pressure-sensitive adhesive layer is preferably 25% by volume or less, more preferably 20% by volume or less (for example, 16% by volume or less, typically 14% by volume or less). From the viewpoint of reducing the tensile peeling stress, the content C is suitably at least 0.3% by volume, preferably at least 2% by volume, more preferably at least 3% by volume (for example, 5% by volume). %, Typically 10% by volume or more). Since the technology disclosed herein can exhibit a desired effect by adding a small amount of filler particles, the pressure-sensitive adhesive layer (pressure-sensitive adhesive composition) substantially contains a component (dispersant) that improves the dispersibility of the filler particles. May not be included, or may contain the above-mentioned dispersant. The content C [% by volume] of the filler particles is determined based on the weight ratio and density of components other than the filler particles (typically, the adhesive component) in the pressure-sensitive adhesive layer, and the weight ratio and density of the filler particles. For example, by adopting 2.42 g / cm ³ as the density of aluminum hydroxide, the content C [% by volume] of the filler particles in the pressure-sensitive adhesive layer can be determined.

  When the pressure-sensitive adhesive layer contains filler particles, the content of the filler particles (for example, inorganic material particles, typically a metal oxide or a metal hydroxide) in the pressure-sensitive adhesive layer is 100% by weight on a weight basis. It is suitably less than 100 parts by weight based on parts. By appropriately adjusting the particle diameter and the content of the filler particles, it is possible to preferably reduce the tensile peeling stress B while suppressing a decrease in the initial adhesive force A. The content of the filler particles in the pressure-sensitive adhesive layer is preferably 80 parts by weight or less, more preferably 60 parts by weight or less (for example, 45 parts by weight or less, typically 35 parts by weight or less, based on 100 parts by weight of the base polymer. ). In addition, from the viewpoint of reducing the tensile peeling stress, the content is suitably 0.5 parts by weight or more, preferably 3 parts by weight or more, more preferably 5 parts by weight or more, and further more preferably 8 parts by weight. (Eg, 12 parts by weight or more, typically 25 parts by weight or more).

(Acrylic oligomer)
The pressure-sensitive adhesive composition disclosed herein may include an acrylic oligomer. By employing an acrylic oligomer, impact resistance and repulsion resistance can be improved in a well-balanced manner. In the case of curing the pressure-sensitive adhesive composition by actinic energy ray irradiation (for example, UV irradiation), the acrylic oligomer inhibits curing (for example, not cured) as compared with, for example, a rosin-based or terpene-based tackifying resin. (Polymerization inhibition of the reaction monomer). The acrylic oligomer is a polymer containing an acrylic monomer as a constituent monomer component, and is defined as a polymer having a smaller Mw than that of the acrylic polymer.

  The proportion of the acrylic monomer in all the monomer components constituting the acrylic oligomer is typically more than 50% by weight, preferably 60% by weight or more, more preferably 70% by weight or more (for example, 80% by weight). Or more, and 90% by weight or more). In a preferred embodiment, the acrylic oligomer has a monomer composition consisting essentially of only acrylic monomers.

  As the constituent monomer components of the acrylic oligomer, the linear alkyl (meth) acrylates, functional group-containing monomers, and other monomers exemplified as the monomers that can be used for the acrylic polymer can be used. Further, the constituent monomer may contain an alicyclic hydrocarbon group-containing (meth) acrylate. As the monomer component constituting the acrylic oligomer, one or more of the various monomers exemplified above can be used.

As the chain alkyl (meth) acrylate, an alkyl (meth) acrylate in which R ² is C _1-12 (for example, C _1-8 ) in the above formula (1) is preferably used. Preferred examples thereof include methyl methacrylate (MMA), ethyl acrylate, n-butyl acrylate (BA), isobutyl methacrylate, t-butyl acrylate, and 2-ethylhexyl acrylate (2EHA). Among them, MMA is more preferable.

  Preferred examples of the functional group-containing monomer include monomers having a nitrogen atom-containing ring (typically a nitrogen atom-containing heterocycle) such as N-vinyl-2-pyrrolidone and N-acryloylmorpholine; N, N-dimethylamino Amino-containing monomers such as ethyl (meth) acrylate; amide-containing monomers such as N, N-diethyl (meth) acrylamide; carboxy-containing monomers such as AA and MAA; and hydroxyl-containing monomers such as HEA.

  As the alicyclic hydrocarbon group-containing (meth) acrylate, for example, one kind of alicyclic hydrocarbon group-containing (meth) acrylate in which the number of carbon atoms of the alicyclic hydrocarbon group is in the range of 4 to 20 Alternatively, two or more kinds can be used. The number of carbon atoms is preferably 5 or more (for example, 6 or more, typically 8 or more), and preferably 16 or less (for example, 12 or less, typically 10 or less). Preferable examples of the alicyclic hydrocarbon group-containing (meth) acrylate include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentanyl (meth) acrylate. Among them, dicyclopentanyl methacrylate (DCPMA) is more preferable.

  The ratio of the alicyclic hydrocarbon group-containing (meth) acrylate to all the monomer components constituting the acrylic oligomer (that is, the copolymerization ratio) is about 30% by weight or more (for example, from the viewpoint of tackiness and cohesion). It is preferably 50% by weight or more, typically 55% by weight or more, and is preferably about 90% by weight or less (for example, 80% by weight or less, typically 70% by weight or less).

  In a preferred embodiment, the acrylic oligomer contains a chain alkyl (meth) acrylate and / or an alicyclic hydrocarbon group-containing (meth) acrylate as a constituent monomer component. In this embodiment, the proportion of the chain alkyl group-containing and alicyclic hydrocarbon group-containing (meth) acrylic ester in all monomer components constituting the acrylic oligomer is about 80% by weight or more (for example, 90 to 100%). % By weight, typically 95 to 100% by weight). More preferably, the monomer component constituting the acrylic oligomer is substantially composed of a chain alkyl (meth) acrylate and / or an alicyclic hydrocarbon group-containing (meth) acrylate.

When the acrylic oligomer is a copolymer of a monomer mixture containing a chain alkyl (meth) acrylate and an alicyclic hydrocarbon group-containing (meth) acrylate, the chain alkyl (meth) acrylate and the alicyclic hydrocarbon The ratio with the group-containing (meth) acrylate is not particularly limited. In a preferred embodiment, the weight ratio of the weight ratio of the chain alkyl (meth) acrylate (W _A ) to the weight ratio of the alicyclic hydrocarbon group-containing (meth) acrylate (W _B ) in the constituent monomer components of the acrylic oligomer is described. (W _A : W _B ) is 1: 9 to 9: 1, preferably 2: 8 to 7: 3 (for example, 3: 7 to 6: 4, typically 3: 7 to 5: 5). It is.

  Although not particularly limited, the composition (that is, the polymerization composition) of the constituent monomer components of the acrylic oligomer can be set so that the Tg of the acrylic oligomer is from 10 ° C to 300 ° C. Here, the Tg of the acrylic oligomer refers to a value obtained in the same manner as the Tg based on the monomer composition of the acrylic polymer, based on the composition of the monomer components of the acrylic oligomer. The Tg of the acrylic oligomer is preferably 180 ° C. or lower (for example, 160 ° C. or lower) from the viewpoint of initial adhesiveness. Further, the Tg is preferably 60 ° C. or higher (for example, 100 ° C. or higher, typically 120 ° C. or higher) from the viewpoint of the cohesiveness of the pressure-sensitive adhesive.

The Mw of the acrylic oligomer is not particularly limited, but is typically about 0.1 × 10 ^{4 to} 3 × 10 ⁴ . From the viewpoint of improving the adhesive properties (for example, adhesive strength and repulsion resistance), the Mw of the acrylic oligomer is preferably 1.5 × 10 ⁴ or less, more preferably 1 × 10 ⁴ or less, and 0.8 × 10 ⁴ or less. (For example, 0.6 × 10 ⁴ or less) is more preferable. Further, from the viewpoint of the cohesiveness of the pressure-sensitive adhesive, the Mw is preferably 0.2 × 10 ⁴ or more (for example, 0.3 × 10 ⁴ or more). The molecular weight of the acrylic oligomer can be adjusted by using a chain transfer agent as needed in the polymerization.

  The acrylic oligomer can be formed by polymerizing the constituent monomer components. The polymerization method and the polymerization mode are not particularly limited, and conventionally known various polymerization methods (for example, solution polymerization, emulsion polymerization, bulk polymerization, photopolymerization, radiation polymerization, etc.) can be adopted in an appropriate mode. The types and amounts of the polymerization initiators (for example, azo-based polymerization initiators such as AIBN) that can be used as necessary are also substantially as described above, and thus the description will not be repeated here.

  The content of the acrylic oligomer in the pressure-sensitive adhesive composition disclosed herein is suitably, for example, 0.5 parts by weight or more based on 100 parts by weight of the acrylic polymer. From the viewpoint of better exhibiting the effects of the acrylic oligomer, the content of the acrylic oligomer is preferably 1 part by weight or more (for example, 1.5 parts by weight or more, typically 2 parts by weight or more). . Further, from the viewpoint of the curability of the pressure-sensitive adhesive composition and the compatibility with the acrylic polymer, the content of the acrylic oligomer is suitably less than 50 parts by weight (for example, less than 10 parts by weight). It is preferably less than 8 parts by weight (for example, less than 7 parts by weight, typically 5 parts by weight or less). Even with the addition of such a small amount, improvement in impact resistance and repulsion resistance by using an acrylic oligomer can be realized.

(Tackifier)
The pressure-sensitive adhesive layer disclosed herein may be a composition containing a tackifier. The tackifier is not particularly limited, for example, rosin-based tackifier resin, terpene-based tackifier resin, hydrocarbon-based tackifier resin, epoxy-based tackifier resin, polyamide-based tackifier resin, elastomer-based tackifier resin, Various tackifier resins such as a phenol-based tackifier resin and a ketone-based tackifier resin can be used. Such tackifying resins can be used alone or in combination of two or more.

  Specific examples of the rosin-based tackifying resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; and modified rosins obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, and the like. Hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosins, etc. The same applies hereinafter.); Other various rosin derivatives; Examples of the rosin derivative include rosins such as unmodified rosin esterified with alcohols (ie, rosin esterified product) and modified rosin esterified with alcohols (ie, modified rosin esterified product). Esters: Unsaturated rosins modified by unsaturated fatty acids obtained by modifying unmodified rosin or modified rosin with unsaturated fatty acids; Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; Unmodified rosin, modified rosin, unsaturated Rosin alcohols obtained by reducing the carboxy group in fatty acid-modified rosins or unsaturated fatty acid-modified rosin esters; metal salts of rosins (particularly, rosin esters) such as unmodified rosin, modified rosin, and various rosin derivatives; (Unmodified rosin, modified rosin, various rosin derivatives, etc.) Rosin phenol resins obtained by thermal polymerization by adding Lumpur acid catalyst; and the like. When an acrylic polymer is used as the base polymer, it is preferable to use a rosin-based tackifying resin. From the viewpoint of improving the adhesive properties such as adhesive strength, one of the above-mentioned rosin-based tackifying resins is selected alone, or two or three or more kinds having different kinds and properties (for example, softening points) are used in combination. Is more preferable.

  Examples of the terpene-based tackifying resin include terpene resins such as α-pinene polymer, β-pinene polymer, dipentene polymer, etc .; Modified terpene resin). Examples of the modified terpene resin include a terpene modified phenol resin, a styrene modified terpene resin, an aromatic modified terpene resin, a hydrogenated terpene resin, and the like. When an acrylic polymer is used as the base polymer, it is preferable to use a terpene-based tackifying resin (for example, a terpene-modified phenol resin). In particular, from the viewpoint of improving the adhesive properties such as adhesive strength, one or two or more of the above terpene-based tackifying resins (for example, terpene-modified phenolic resins) having different types and properties (for example, softening points) are used in combination. Is preferred.

  Examples of the hydrocarbon-based tackifying resin include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.). ), Various hydrocarbon resins such as aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, cumarone resins, and cumarone indene resins.

  In the technology disclosed herein, a resin having a softening point (softening temperature) of about 70 ° C. or more (preferably about 100 ° C. or more, more preferably about 110 ° C. or more) can be preferably used as the tackifier resin. According to the pressure-sensitive adhesive containing the tackifier resin having a softening point not lower than the lower limit described above, a pressure-sensitive adhesive sheet having more excellent adhesive strength can be realized. Among the tackifier resins exemplified above, terpene-based tackifier resins having the above softening point (for example, terpene-modified phenol resin), rosin-based tackifier resins (for example, esterified products of polymerized rosin) and the like can be preferably used. The upper limit of the softening point of the tackifier resin is not particularly limited, and may be, for example, about 200 ° C. or less (typically about 180 ° C. or less). Here, the softening point of the tackifier resin is defined as a value measured by a softening point test method (ring and ball method) specified in either JIS K 5902 or JIS K 2207.

  The amount of the tackifier used is not particularly limited, and can be appropriately set according to the desired tackiness performance (adhesive strength and the like). For example, the tackifier may be used in an amount of about 10 parts by weight or more (more preferably 20 parts by weight or more, further preferably 30 parts by weight or more) based on 100 parts by weight of the acrylic polymer on a solid content basis. Preferably, it is used at a ratio of about 100 parts by weight or less (more preferably 80 parts by weight or less, further preferably 60 parts by weight or less). The technology disclosed herein may be implemented in a mode including a pressure-sensitive adhesive layer substantially free of a tackifier.

  When the pressure-sensitive adhesive layer is composed of a rubber-based pressure-sensitive adhesive, the rubber-based pressure-sensitive adhesive preferably contains a high softening point resin having a softening point of 120 ° C. or higher as a tackifying resin. The pressure-sensitive adhesive sheet of such an embodiment is preferable from the viewpoint of repulsion resistance, holding power, and the like. In a preferred embodiment, the high softening point resin may include a tackifier resin having a softening point of 125 ° C. or higher (more preferably 130 ° C. or higher, even more preferably 135 ° C. or higher, for example, 140 ° C. or higher). In addition, from the viewpoint of adhesive strength to an adherend and the like, the softening point of the high softening point resin is usually 200 ° C or lower, preferably 180 ° C or lower, more preferably 170 ° C or lower (eg, 160 ° C or lower). ).

  As the high softening point resin, terpene phenol resin, polymerized rosin, esterified product of polymerized rosin and the like can be preferably used. These high softening point resins can be used singly or in an appropriate combination of two or more. In a preferred embodiment, the high softening point resin includes one or more terpene phenol resins. For example, a terpene phenol resin having a softening point of 120 ° C to 200 ° C (typically 120 ° C to 180 ° C, for example, 125 ° C to 170 ° C) can be preferably used.

  As the terpene phenol resin, those having a softening point of 120 ° C. or higher and a hydroxyl value (OH value) of 40 mg KOH / g or more (typically 40 to 200 mg KOH / g, for example, 40 to 160 mg KOH / g) are preferable. Can be adopted. According to the terpene phenol resin having such a hydroxyl value, a higher-performance pressure-sensitive adhesive sheet can be realized. As the value of the hydroxyl value in this specification, a value measured by a potentiometric titration method specified in JIS K 0070: 1992 can be adopted. As a specific measuring method, a method described in JP-A-2014-55235 is employed.

  The technology disclosed herein is, for example, that the rubber-based pressure-sensitive adhesive has a high softening point resin (H1) having a hydroxyl value of 40 mgKOH / g or more and less than 80 mgKOH / g, and a hydroxyl value of 80 mgKOH / g or more (typically 80 to 80 mgKOH / g). 160 mgKOH / g, for example, 80 to 140 mgKOH / g), which can be preferably used in combination with a high softening point resin (H2). In this case, the relationship between the amounts of the high softening point resin (H1) and the high softening point resin (H2) used is such that the weight ratio (H1: H2) is in the range of 1: 5 to 5: 1. It is usually appropriate to set the ratio to be in the range of 1: 3 to 3: 1 (for example, 1: 2 to 2: 1). In a preferred embodiment, both the high softening point resin (H1) and the high softening point resin (H2) are terpene phenol resins.

  From the viewpoints of repulsion resistance and holding power, the content of the high softening point resin can be, for example, 20 parts by weight or more, and 30 parts by weight or more (for example, 35 parts by weight or more) based on 100 parts by weight of the base polymer. ) Is preferable. From the viewpoints of adhesive strength and low-temperature properties, the content of the high softening point resin to 100 parts by weight of the base polymer is usually 100 parts by weight or less, preferably 80 parts by weight or less, more preferably 80 parts by weight or less. Is 70 parts by weight or less. The content of the high softening point resin may be 60 parts by weight or less (for example, 50 parts by weight or less).

  The technology disclosed herein is an embodiment in which the rubber-based pressure-sensitive adhesive contains a low softening point resin having a softening point of less than 120 ° C. instead of the high softening point resin or in addition to the high softening point resin. Can be implemented. As a preferred embodiment, there is an embodiment in which the rubber-based pressure-sensitive adhesive contains a high softening point resin having a softening point of 120 ° C or more and a low softening point resin having a softening point of less than 120 ° C.

  As the low softening point resin, those having a softening point of, for example, 40 ° C. or more (typically 60 ° C. or more) can be used. From the viewpoints of repelling resistance, holding power, and the like, usually, those having a softening point of 80 ° C. or more (more preferably 100 ° C. or more) and less than 120 ° C. can be preferably used. You may use the low softening point resin whose softening point is 110 to 120 degreeC.

  The technology disclosed herein can be preferably implemented in a mode in which the rubber-based pressure-sensitive adhesive contains at least one of a petroleum resin and a terpene resin (typically, an unmodified terpene resin) as the low softening point resin. For example, the main component of the low softening point resin (that is, the component that accounts for more than 50% by weight of the low softening point resin) is a composition that is a petroleum resin, a composition that is a terpene resin, or a combination of a petroleum resin and a terpene resin. A certain composition or the like can be preferably employed. From the viewpoint of adhesive strength and compatibility, an embodiment in which the main component of the low softening point resin is a terpene resin (for example, a β-pinene polymer) is preferable. Substantially all (for example, 95% by weight or more) of the low softening point resin may be a terpene resin.

  In a preferred embodiment, the low softening point resin may be a tackifier resin having a hydroxyl value of 0 or more and less than 80 mgKOH / g (low hydroxyl value tackifier resin). As the low hydroxyl value tackifying resin, those having a hydroxyl value in the above range among the various tackifying resins described above can be used alone or in an appropriate combination. For example, a terpene phenol resin having a hydroxyl value of 0 or more and less than 80 mgKOH / g, a petroleum resin (for example, C5 petroleum resin), a terpene resin (for example, β-pinene polymer), a rosin-based resin (for example, polymerized rosin), rosin A derivative resin (for example, an esterified product of a polymerized rosin) or the like can be used.

  From the viewpoint of the adhesive force to the adherend, the content of the low softening point resin can be, for example, 10 parts by weight or more, and usually 15 parts by weight or more (for example, 20 parts by weight) based on 100 parts by weight of the base polymer. Above) is appropriate. In addition, from the viewpoint of rebound resistance and the like, it is usually appropriate to set the content of the low softening point resin to 120 parts by weight or less, preferably 90 parts by weight or less, more preferably 70 parts by weight or less (for example, 60 parts by weight or less). Parts by weight or less). The content of the low softening point resin may be 50 parts by weight or less (for example, 40 parts by weight or less).

  When the tackifying resin contains a low softening point resin and a high softening point resin, the weight ratio of the low softening point resin to the high softening point resin is 1: 5 to 3: 1 (more preferably). Is preferably set to be 1: 5 to 2: 1). The technology disclosed herein relates to a mode in which the rubber-based pressure-sensitive adhesive contains a higher softening point resin as a tackifying resin than a low softening point resin (for example, when the weight ratio of the low softening point resin to the high softening point resin is 1). : 1.2 to 1: 5). According to this aspect, a higher-performance pressure-sensitive adhesive sheet can be realized.

  In the technology disclosed herein, the content of the tackifying resin to 100 parts by weight of the base polymer (typically, a rubber-based polymer) is generally appropriate to be 20 parts by weight or more, and preferably 30 parts by weight. As described above, it is more preferably at least 40 parts by weight (for example, at least 50 parts by weight). In addition, from the viewpoint of low-temperature characteristics (for example, adhesive strength and impact resistance under low-temperature conditions), the content of the tackifier resin to 100 parts by weight of the base polymer is usually 200 parts by weight or less. , Preferably 150 parts by weight or less. The content of the tackifier resin to 100 parts by weight of the base polymer may be 100 parts by weight or less (for example, 80 parts by weight or less).

(Crosslinking agent)
The pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer disclosed herein may include a crosslinking agent as necessary. The type of the crosslinking agent is not particularly limited, and can be appropriately selected from conventionally known crosslinking agents. Examples of such a crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, metal chelate-based crosslinking agents, and the like. Can be As the crosslinking agent, one kind can be used alone, or two or more kinds can be used in combination. Above all, from the viewpoint of improving cohesive strength, use of an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent is preferred, and an isocyanate-based crosslinking agent is more preferred.

  The amount of the crosslinking agent is not particularly limited, and is, for example, about 10 parts by weight or less (for example, about 0.005 to 10 parts by weight, preferably about 0.01 to about 100 parts by weight based on 100 parts by weight of the base polymer (eg, acrylic polymer)). 5 parts by weight). The technology disclosed herein can achieve a desired tensile peeling stress B without reducing the amount of the cross-linking agent used. Therefore, the amount of the cross-linking agent used is approximately 0 with respect to 100 parts by weight of the acrylic polymer. 0.1 parts by weight or more (for example, 0.8 parts by weight or more, typically 1.2 parts by weight or more). Further, from the viewpoint of reducing the cohesive force and reducing the tensile peeling stress B, the amount of the crosslinking agent used is about 5 parts by weight or less (for example, 3 parts by weight or less, typically about 100 parts by weight of the acrylic polymer). May be 2 parts by weight or less).

(Other components)
The pressure-sensitive adhesive composition may contain a leveling agent, a crosslinking assistant, a plasticizer, a softener, a coloring agent (dye or pigment), an antistatic agent, an antioxidant, an ultraviolet absorber, an antioxidant, It may contain various additives commonly used in the field of pressure-sensitive adhesive compositions, such as stabilizers and dispersants. In addition, for example, an adhesive agent such as a silicone oligomer may be added to the adhesive composition (typically, an acrylic adhesive composition). As for such various additives, conventionally known ones can be used in a conventional manner, and do not particularly characterize the present invention, and thus detailed description thereof will be omitted.

(Adhesive composition)
The pressure-sensitive adhesive layer disclosed herein may be a pressure-sensitive adhesive layer formed from a water-based pressure-sensitive adhesive composition, a solvent-based pressure-sensitive adhesive composition, a hot-melt-type pressure-sensitive adhesive composition, or an active energy ray-curable pressure-sensitive adhesive composition. . The water-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in the form of a pressure-sensitive adhesive (pressure-sensitive adhesive layer-forming component) in a solvent containing water as a main component (water-based solvent), and is typically dispersed in water. And a so-called pressure-sensitive adhesive composition (a composition in which at least a part of the pressure-sensitive adhesive is dispersed in water). Further, the solvent-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in a form containing a pressure-sensitive adhesive in an organic solvent. The technology disclosed herein is preferably implemented in an aspect including an adhesive layer formed from a solvent-type adhesive composition from the viewpoint of suitably realizing adhesive properties such as adhesive strength.

(Method of forming pressure-sensitive adhesive layer)
The pressure-sensitive adhesive layer disclosed herein can be formed by a conventionally known method. For example, a method of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive composition to a releasable surface (peeling surface) and drying the pressure-sensitive adhesive composition can be employed. Alternatively, a method (direct method) of forming a pressure-sensitive adhesive layer by directly applying (typically, applying) the pressure-sensitive adhesive composition to a film-like substrate and drying the pressure-sensitive adhesive composition can be employed. Further, a method of transferring a pressure-sensitive adhesive composition to a film-like substrate by forming a pressure-sensitive adhesive layer on the surface by applying and drying the pressure-sensitive adhesive composition on a surface having a releasable property (release surface) (transfer) Method). As the release surface, the surface of a release liner, the back surface of a substrate subjected to a release treatment, or the like can be used. In addition, the pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but is not limited to such a form.For example, a point-like, stripe-like or other regular or random pattern The formed pressure-sensitive adhesive layer may be used.

  The application of the pressure-sensitive adhesive composition can be performed using a conventionally known coater such as a gravure roll coater, a die coater, and a bar coater. Alternatively, the pressure-sensitive adhesive composition may be applied by impregnation, curtain coating, or the like. The drying of the pressure-sensitive adhesive composition is preferably performed under heating from the viewpoint of accelerating a crosslinking reaction, improving production efficiency, and the like. The drying temperature can be, for example, 40 ° C. or higher (preferably 60 ° C. or higher), for example, 150 ° C. or lower (preferably 130 ° C. or lower). After drying the pressure-sensitive adhesive composition, further aging may be performed for the purpose of adjusting the migration of components in the pressure-sensitive adhesive layer, progressing the cross-linking reaction, and reducing strain that may be present in the substrate or the pressure-sensitive adhesive layer. Good.

(Thickness of adhesive layer)
The thickness of the pressure-sensitive adhesive layer disclosed herein is not particularly limited, and can be appropriately selected depending on the purpose. Usually, the thickness of the pressure-sensitive adhesive layer is suitably 3 μm or more, preferably 5 μm or more, more preferably 8 μm or more, and still more preferably 15 μm or more from the viewpoint of adhesive performance and the like. The thickness is suitably 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less from the viewpoint of productivity such as drying efficiency. In the case of a double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on both sides of a film-like substrate, the thickness of each pressure-sensitive adhesive layer may be the same or different.

<Film substrate>
It is preferable that the film-shaped substrate disclosed herein has a breaking strength of 10 MPa or more. By using a film-shaped substrate exhibiting the above-mentioned breaking strength, the pressure-sensitive adhesive sheet becomes more difficult to be broken, and can exhibit excellent tensile removability. According to the film-shaped substrate having the above-mentioned breaking strength, the processability tends to be improved. The breaking strength is more preferably 30 MPa or more (for example, 45 MPa or more, typically 60 MPa or more). In addition, from the viewpoint of the elasticity and extensibility of the film-like substrate, the breaking strength is preferably about 100 MPa or less (for example, 90 MPa or less, typically 80 MPa or less). The breaking strength is measured by the same method as in the case of the pressure-sensitive adhesive sheet. The breaking strength of the substrate can be adjusted, for example, by selecting the type of the substrate material (selection of the mixing ratio of the hard component and the soft component, etc.), the molding method, and the like.

  It is preferable that the film-shaped substrate disclosed herein exhibits an elongation at break of 300% or more. The substrate exhibiting the elongation at break elongates in response to the tension when the adhesive sheet is removed. Due to this extension, the pressure-sensitive adhesive sheet is deformed and peeled from the adherend. As described above, the tension and the deformation of the base material interact with each other, so that the pressure-sensitive adhesive sheet is further improved in the tension-removability (particularly, the shear-removability). The elongation at break is more preferably 500% or more (for example, 700% or more, typically 800% or more). The upper limit of the elongation at break is not particularly limited, but may be, for example, about 1000% or less (typically 900% or less) from the viewpoint of removal workability and the like. The elongation at break is measured by the same method as in the case of the pressure-sensitive adhesive sheet.

  The film-like substrate disclosed herein suitably has a tensile recovery of more than 50%, and the above-mentioned tensile recovery is preferably 70% or more. The tensile recovery is more preferably 80% or more (for example, 90% or more, typically 93% to 100%). Thereby, damage such as breakage during the removal of the pressure-sensitive adhesive sheet can be more highly prevented. The measurement of the tensile recovery rate is performed by the same method as the method for measuring the tensile recovery rate of the pressure-sensitive adhesive sheet. The tensile recovery rate of the substrate can be adjusted, for example, by selecting the type of the substrate material (selection of the mixing ratio of the hard component and the soft component, etc.), the molding method, and the like.

  Preferably, the film-like substrate disclosed herein exhibits a 5% modulus of less than 10 MPa. When the 5% modulus of the film-like base material is set to be less than the predetermined value, when the pressure-sensitive adhesive sheet is removed from the adherend by elongating and deforming, the resistance at the start of pulling becomes small and the tensile-removing property tends to be excellent. is there. The 5% modulus is more preferably less than 5 MPa (eg, less than 3 MPa, typically less than 2 MPa). Although the lower limit of the 5% modulus is not particularly limited, it is usually appropriate to set it to 0.5 MPa or more (for example, 1 MPa or more) from the viewpoint of sticking workability of the pressure-sensitive adhesive sheet. The 5% modulus is measured according to the method for measuring “tensile stress” described in JIS K 7311: 1995. More specifically, a tensile test was performed using a No. 3 dumbbell-shaped test piece (width: 5 mm, mark interval: 20 mm) at a tensile speed of 300 mm / min. ] Is 5% modulus. As the tensile tester, a product name “Autograph AG-10G type tensile tester” manufactured by Shimadzu Corporation can be used. The 5% modulus of the base material can be adjusted by, for example, selection of a base material type (selection of a mixing ratio of a hard component and a soft component), a molding method, and the like.

  Preferably, the film-like substrates disclosed herein exhibit a 100% modulus of less than 10 MPa. When the 100% modulus of the film-like substrate is less than a predetermined value, when the pressure-sensitive adhesive sheet is pulled from the adherend by elongating and deforming, the resistance at the start of pulling becomes small and the tensile-removing property tends to be excellent. is there. The 100% modulus is more preferably less than 5 MPa. Although the lower limit of the 100% modulus is not particularly limited, it is usually suitable to be 0.5 MPa or more (for example, 1 MPa or more) from the viewpoint of the workability of sticking the pressure-sensitive adhesive sheet. The 100% modulus is measured by the same method as in the case of the pressure-sensitive adhesive sheet.

  Preferably, the film-like substrate disclosed herein exhibits a 150% modulus of less than 20 MPa. When the 150% modulus of the film-shaped substrate is set to be less than the predetermined value, when the pressure-sensitive adhesive sheet is removed from the adherend by being stretched and deformed, the resistance at the time of the tension removing operation tends to decrease. The 150% modulus is more preferably less than 15 MPa (eg less than 12 MPa, typically less than 8 MPa). Although the lower limit of the 150% modulus is not particularly limited, it is usually appropriate to set it to 1 MPa or more (for example, 5 MPa or more) from the viewpoint of sticking workability of the pressure-sensitive adhesive sheet. The 150% modulus is measured according to the method for measuring “tensile stress” described in JIS K 7311: 1995. More specifically, using a No. 3 dumbbell-shaped test piece (width 5 mm, mark interval 20 mm), the sample was pulled at a tensile speed of 300 mm / min, and the stress [MPa when the mark length was extended by 150%. ] Is set to 150% modulus. As the tensile tester, a product name “Autograph AG-10G type tensile tester” manufactured by Shimadzu Corporation can be used. The 150% modulus of the base material can be adjusted by, for example, selection of a base material type (selection of a mixing ratio of a hard component and a soft component), a molding method, and the like.

As a film-like substrate (supporting substrate) for supporting (lining) the pressure-sensitive adhesive layer, various film-like substrates can be used. As the base material, for example, a woven fabric film, a nonwoven fabric film, and a resin film can be used. Above all, a resin film is preferable. The resin film may be a non-foamed resin film, a rubbery film, a foamed film, or the like. Of these, non-foamed resin films and rubbery films are preferred, and non-foamed resin films are more preferred. Non-foamed resin films have substantially no air bubbles (voids) that can be a weak point in terms of mechanical strength, and tend to have superior mechanical strength such as tensile strength as compared with foams. The non-foamed resin film is also excellent in workability, dimensional stability, thickness accuracy, economy (cost), and the like.
The “resin film” in this specification is a substantially non-porous film, and has a concept distinguished from a so-called nonwoven fabric or woven fabric (ie, a concept excluding nonwoven fabric or woven fabric). In addition, the non-foamed resin film refers to a resin film that has not been intentionally treated to be a foam. The non-foamed resin film may specifically be a resin film having an expansion ratio of less than 1.1 times (for example, less than 1.05 times, typically less than 1.01 times). The non-foamed resin film includes, for example, soft resin films called soft polyolefin, soft polyurethane, soft polyester, soft polyvinyl chloride, and the like.

  Preferred examples of the resin material constituting the resin film disclosed herein include polyurethanes such as ether-based polyurethane, ester-based polyurethane, and carbonate-based polyurethane; urethane (meth) acrylate-based polymers; polyethylene (PE), and polypropylene (PP). And polyolefins such as ethylene-propylene copolymers and ethylene-butene copolymers; polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate and polybutylene naphthalate; polycarbonates; As the above polyester, polybutylene terephthalate (PBT), polyethylene naphthalate, and polybutylene naphthalate are more preferable. The resin material is a styrene-based copolymer such as a styrene-butadiene copolymer, a styrene-isoprene copolymer, a styrene-ethylene-butylene copolymer, a styrene-ethylene-propylene copolymer, a styrene-butadiene-styrene copolymer, and a styrene-isoprene-styrene copolymer. It may be a coalesced (typically a styrene elastomer), an acrylic copolymer called acrylic rubber, or a vinyl chloride resin (PVC) such as soft polyvinyl chloride. Good. The above resin materials can be used alone or in combination of two or more. The above-mentioned resin materials include those generally called rubber or thermoplastic elastomer.

  In a preferred embodiment, the film substrate is a polyurethane resin film. Here, the polyurethane-based resin film refers to a resin film containing polyurethane as a main component of the resin component (a component having the highest blending ratio, typically a component containing more than 50% by weight; the same applies hereinafter). . Polyurethane resin film is typically composed of a material that does not substantially exhibit a yield point, and is a film material that is easy to realize a pressure-sensitive adhesive sheet that exhibits a predetermined breaking strength and elongation and, if necessary, a tensile recovery rate. It is. Polyurethane-based resin films can also achieve good physical properties without adding additional components such as plasticizers, for example. It can be a material.

  The proportion of polyurethane in the resin component contained in the polyurethane resin film is preferably 70% by weight or more (for example, 80% by weight or more, typically 90% by weight or more and 100% by weight or less). The polyurethane resin film disclosed herein may be a film composed of a polymer blend of polyurethane and another resin. The other resin may be, for example, one or more of acrylic resin, polyolefin, polyester, and polycarbonate. Alternatively, the technology disclosed herein can also be implemented in an embodiment using a base material substantially free of resin components other than polyurethane.

  The polyurethane is a polymer compound synthesized by performing a polyaddition reaction between a polyol (for example, a diol) and a polyisocyanate (for example, a diisocyanate) at a predetermined ratio. The NCO / OH ratio of the polyurethane may be appropriately set based on technical common sense of those skilled in the art so that desired mechanical properties (for example, breaking strength, elongation at break, and tensile recovery rate) are obtained.

  Examples of the polyol that can be used for the synthesis of the polyurethane include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, and 1,6-hexane. Diols such as diol, 1,8-octanediol, polyoxytetramethylene glycol, diethylene glycol, polyethylene glycol and polypropylene glycol; polyesters which are polycondensates of the above diols with dicarboxylic acids (eg, adipic acid, azelaic acid, sebacic acid) Polyol; carbonate diols such as polyalkylene carbonate diol; and the like. These can be used alone or in combination of two or more.

  Examples of the polyisocyanate that can be used for the synthesis of the polyurethane include aromatic, aliphatic, and alicyclic diisocyanates, and multimers (for example, dimers and trimers) of these diisocyanates. Examples of the diisocyanate include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, and 1,3-phenylene diisocyanate. 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, dicyclohexylmethane-4 1,4-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexyl Down diisocyanate, m- tetramethylxylylene diisocyanate, and the like. These can be used alone or in combination of two or more. Of these, aromatic diisocyanates are preferred.

  In the polyurethane, other copolymer components may be introduced in addition to the polyol and the polyisocyanate. As other copolymerization components, one or more of monocarboxylic acid, dicarboxylic acid, trifunctional or higher polycarboxylic acid, hydroxycarboxylic acid, alkoxycarboxylic acid, and derivatives thereof can be used. The proportion of these other copolymer components is suitably less than 30% by weight (eg, less than 10% by weight, typically less than 5% by weight) in the polyurethane. The technology disclosed herein can also be preferably implemented in an embodiment having a polyurethane-based resin film base material containing, as a main component, polyurethane containing no other copolymer component.

  In another preferred embodiment, the film-shaped substrate is a resin film containing a urethane (meth) acrylate-based polymer. As the urethane (meth) acrylate-based polymer disclosed herein, a polymer containing a structural unit derived from urethane (meth) acrylate can be used. Here, urethane (meth) acrylate refers to a compound having a urethane bond and a (meth) acryloyl group in one molecule, and such a compound can be used without any particular limitation. Urethane (meth) acrylates can be used alone or in combination of two or more. The urethane (meth) acrylate preferably has two or more urethane bonds and two or more (meth) acryloyl groups. The number of the (meth) acryloyl groups in the urethane (meth) acrylate is preferably from 2 to 5, and more preferably from 2 to 3. For example, urethane (meth) acrylate having two (meth) acryloyl groups can be preferably used. Further, the urethane (meth) acrylate is preferably urethane acrylate. Here, the “urethane acrylate” refers to one in which the number ratio of acryloyl groups among the (meth) acryloyl groups included in urethane (meth) acrylate exceeds 50%.

  As the urethane (meth) acrylate, various commercially available urethane (meth) acrylates can be used. For example, a product name “UV-3300B” manufactured by Nippon Synthetic Chemical Industry Co., Ltd., a product name “Beam Set 505A-6” manufactured by Arakawa Chemical Industry Co., Ltd. can be preferably used.

  In another preferred embodiment, the film-shaped substrate is a PVC-based resin film. The PVC resin film is produced by forming a PVC resin composition (molding material) containing a PVC resin into a film. Here, the PVC resin composition refers to a resin composition in which the main component (that is, 50% by weight or more) of the resin component (polymer component) is a PVC resin (typically, PVC). It is preferable that about 80% by weight or more (more preferably about 90% by weight or more) of the total amount of resin components contained in the PVC-based resin composition is a PVC-based resin. Substantially all of the resin component may be PVC. According to such a PVC-based resin composition, a PVC-based resin film exhibiting suitable physical properties as a base material of the pressure-sensitive adhesive sheet can be formed.

  The film-like base material (for example, a resin film base material) may have a filler (inorganic filler, organic filler, etc.), a coloring agent (pigment, dye), an antioxidant, an antioxidant, and an ultraviolet absorber as necessary. Various additives such as an agent, an antistatic agent, a lubricant, a plasticizer, and a stabilizer may be compounded. For example, when using a soft PVC resin film as the film-like base material, the blending amount of the plasticizer should be about 20 parts by weight or more (more preferably about 30 parts by weight or more) per 100 parts by weight of the PVC resin. It is appropriate that the amount is approximately 100 parts by weight or less (more preferably, approximately 70 parts by weight or less). The mixing ratio of the various additives is usually less than 30% by weight (for example, less than 20% by weight, typically less than 10% by weight).

  Conventionally known surface treatments such as a corona discharge treatment, a plasma treatment, an ultraviolet irradiation treatment, an acid treatment, an alkali treatment, and the application of a primer may be applied to the surface of the film-shaped substrate. Such a surface treatment may be a treatment for improving the adhesion between the film-shaped substrate and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer on the substrate. When the film-like substrate is a polyurethane-based resin film, good anchoring properties can be obtained even if the above-mentioned surface treatment is not performed, due to the high surface energy.

  The film-shaped substrate may have a single-layer structure, a two-layer structure, a three-layer structure or a multi-layer structure of more layers. In the case of a multi-layer structure, at least one layer (preferably all layers) is preferably a layer having a continuous structure of the resin (more preferably polyurethane). The method for producing the film-shaped substrate is not particularly limited as long as a conventionally known method is appropriately employed. When a resin film substrate is employed as the film substrate, for example, extrusion molding, inflation molding, T-die cast molding, and a conventionally known general film forming method such as calender roll molding are appropriately employed. A resin film substrate can be used.

  The thickness of the film-shaped substrate is not particularly limited, and can be appropriately selected depending on the purpose. Usually, it is appropriate that the thickness is 10 μm or more, and it is preferably about 30 μm or more (for example, 40 μm or more, typically 70 μm or more). A film-like substrate having the above thickness is difficult to be broken and can be excellent in tensile removability. It is appropriate that the thickness of the film-shaped substrate is 3 mm or less (for example, 2 mm or less, typically 1.5 mm or less). Further, the thickness of the film-shaped substrate is preferably 300 μm or less, more preferably 200 μm or less (for example, 150 μm or less, typically 120 μm or less). For example, the above thickness is preferably adopted for a non-foamed resin film substrate. According to the technology disclosed herein, even in a configuration using a base material having a thickness equal to or less than the above-described predetermined thickness, it is possible to achieve good tensile removability. Reducing the thickness of the film-shaped substrate is advantageous in terms of reducing the thickness of the pressure-sensitive adhesive sheet, miniaturizing it, reducing its weight, saving resources, and the like.

<Release liner>
As the release liner, a conventional release paper or the like can be used and is not particularly limited. For example, a release liner having a release treatment layer on the surface of a liner substrate such as a resin film or paper, or a low-adhesion material such as a fluoropolymer (such as polytetrafluoroethylene) or a polyolefin resin (such as polyethylene or polypropylene). A release liner or the like can be used. The release treatment layer may be formed, for example, by subjecting the liner substrate to a surface treatment with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

<Tab>
The tabs that can be provided on the extensible pressure-sensitive adhesive sheet disclosed herein are not limited in terms of shape, material, and the like as long as the tabs exhibit their functions. The tab basically has a planar shape, and functions as a tab when viewed from above, such as a triangle, a circle, an ellipse, a semicircle, a semi-ellipse, and a band. Various shapes can be adopted within the range in which they are exhibited. The tab according to a preferred embodiment is a rectangular resin film. As for the material of the tab, any material may be used as long as it has a rigidity enough to withstand the tension when removing the extensible pressure-sensitive adhesive sheet. For example, the material exemplified as the material of the above-mentioned film-like base material (for example, a resin film such as a PET film, a nonwoven fabric) , Woven cloth, etc.).

  The tab preferably has a breaking strength of 10 MPa or more. This prevents damage such as breakage of the tab when the extensible pressure-sensitive adhesive sheet is peeled off. Also, it tends to have excellent workability. The breaking strength is more preferably 20 MPa or more, and still more preferably 30 MPa or more (for example, 45 MPa or more, typically 60 MPa or more). The breaking strength is measured by the method described above.

  At least one of the outer surfaces of the tab (at least one (preferably both) of the front (front) side and the back (back) side) is typically non-tacky and at least low tacky Preferably, there is. Specifically, the outer surface of the tab may exhibit a peel strength of less than 1 N / 20 mm (180 ° peel strength to stainless steel plate). The peel strength is measured by the method described above. In the present specification, a surface having a peel strength of less than 1 N / 20 mm (typically, the outer surface of the tab) is referred to as “non-adhesive”. In addition, that the outer surface of the tab has low adhesiveness means that the outer surface of the tab has a lower adhesive strength (typically, 180 ° peel strength with respect to SUS) as compared with the surface (adhesive surface) of the extensible adhesive sheet. Say. The tab is typically non-tacky on both sides of its outer surface, but one may be non-tacky and the other low tack.

  Although the thickness of the tab is not particularly limited, it is preferable that the tab has a predetermined thickness or more in order to have a strength that does not break when the stretchable pressure-sensitive adhesive sheet is pulled. Usually, the thickness of the tab is suitably 10 μm or more, and preferably about 30 μm or more (for example, 40 μm or more, typically 70 μm or more). The thickness of the tab is suitably 3 mm or less (eg, 2 mm or less, typically 1.5 mm or less), and the thickness of the tab 50 is preferably 300 μm or less, and 200 μm or less (eg, 150 μm or less). Hereinafter, typically, it is more preferably 120 μm or less.

<Extension assist film>
(Structure of stretching aid film)
Here, the extension assisting film may have, for example, a cross-sectional structure schematically shown in FIG. The stretch assisting film 250 shown in FIG. 11 includes a film-shaped resin base 260 constituting the back 250B of the stretch assisting film 250, an adhesive layer 270 provided on one surface (one side) of the resin base 260, Is provided. The extension assisting film 250 has a surface 250A on the pressure-sensitive adhesive layer 270 side (a surface to be adhered to an adherend; hereinafter, also referred to as an adhesive surface) 250A adhered to an end (typically a corner) of the adherend. Used. In addition, the back surface 250B of the extension assisting film 250 is in contact with one adhesive surface of the extensible adhesive sheet that joins one object and another object. The stretching aid film 250 before use (that is, before affixing to an adherend) is typically protected on the adhesive surface 250A by a release liner (not shown) having a release surface on at least the adhesive layer 270 side. It can be in the form. Alternatively, the other surface of the resin substrate 260 (the surface of the extension assisting film 250 opposite to the surface on which the adhesive layer 270 is provided; the back surface 250B of the extension assisting film 250) is a release surface, and the extension assisting film 250 May be in a form in which the adhesive layer 270 is in contact with the other surface by being wound in a roll shape to protect the surface (adhesive surface).

(Characteristics of stretch assist film)
The extension assisting film disclosed herein preferably has a rear surface having a dynamic friction coefficient of 0.20 or less. Thus, by setting the coefficient of dynamic friction on the back of the stretch assisting film to be low, when the stretchable pressure-sensitive adhesive sheet is removed (typically pulled out), the resistance of the stretchable pressure-sensitive adhesive sheet to tension is reduced, and the stretchable pressure-sensitive adhesive sheet is removed. Can be pulled out smoothly. As a result, deformation or breakage of the adherend is preferably prevented. In addition, the extensible pressure-sensitive adhesive sheet is also more difficult to cut. The dynamic friction coefficient is more preferably 0.15 or less, further preferably 0.12 or less (for example, 0.11 or less, further preferably 0.10 or less).

  As the kinetic friction coefficient, a value obtained by measuring the kinetic friction coefficient with respect to a 10 mmφ steel ball on the back surface of the stretching assist film in accordance with ASTM D1894 is employed. Specifically, the dynamic friction coefficient was measured by using a reciprocating friction tester (“MODEL AFT-15B”, manufactured by Orientec Co., Ltd.), using a steel ball with a diameter of 10 mm as a mating material, a load of 200 gf, and a slip assist of 100 mm / min. It can be obtained by measuring the coefficient of dynamic friction on the back of the film. The dynamic friction coefficient in the examples described later is measured in the same manner.

  In another preferred embodiment, a part of the back surface of the stretch assisting film disclosed herein has a coefficient of kinetic friction of 0.20 or less. Part of the back surface includes at least a portion that comes into contact with the extensible pressure-sensitive adhesive sheet when the extensible pressure-sensitive adhesive sheet is removed. Typically, a part of the back surface is, for example, in FIGS. 1 and 3, a bent portion of the extension assisting film 50 attached to a corner 80 </ b> C of the object 80 (a convex portion bent corresponding to the corner 80 </ b> C). Can be As described above, even when only a part of the back surface of the stretching assist film is set to have a dynamic friction coefficient of 0.20 or less, the same effect as when the dynamic friction coefficient of the entire back surface is set to a predetermined value or less can be obtained. The coefficient of dynamic friction of a part of the back surface is more preferably 0.15 or less, further preferably 0.12 or less (for example, 0.11 or less, further preferably 0.10 or less). When the kinetic friction coefficient is set to a predetermined value or less for only a part of the back surface of the stretching assist film, it is preferable to perform a process for setting the kinetic friction coefficient to 0.20 or less for the part. Such a treatment can be various surface treatments such as application of a treatment agent such as a fluoropolymer or a silicone.

  The arithmetic average surface roughness (Ra) on the back surface of the stretching assist film is preferably about 1 μm or less, and is 0.75 μm or less (eg, about 0.5 μm or less, typically about 0.3 μm or less). More preferably, it is preferably 0.05 μm or more (for example, 0.1 μm or more). By using the stretch assisting film having the back surface with high smoothness as described above, it is possible to suppress a decrease in the adhesiveness at the position where the stretch assisting film is disposed in joining with the stretchable adhesive sheet. For example, according to the stretch assisting film having a dynamic friction coefficient of 0.20 or less and Ra having a back surface of 0.5 μm or less, the adhesion of the stretchable adhesive sheet does not hinder the adhesion of the stretchable adhesive sheet at the time of joining an object. At the time of peeling, smoother peeling becomes possible, and deformation and breakage of the adherend and shredding of the extensible adhesive sheet are more preferably prevented. In addition, by using a stretchable auxiliary film having high smoothness, when the stretchable pressure-sensitive adhesive sheet is removed, the bias of the stress is reduced, and defects caused by local stress (such as a decrease in peeling property, an adherend or an elongation). And the like) can be avoided. Alternatively, in another preferred embodiment, Ra on the back surface of the stretching assist film is larger than 0.4 μm. Thereby, the peelability of the extensible pressure-sensitive adhesive sheet tends to be improved. From the same viewpoint, Ra is more preferably larger than 0.5 μm, further preferably larger than 0.75 μm, and particularly preferably 0.9 μm or more (for example, 1.2 μm or more).

  The stretch assist film disclosed herein preferably has a 180-degree peel strength (with respect to SUS adhesive strength) against a stainless steel plate (SUS plate) of 3 N / 20 mm or more. Thereby, the extension assisting film adheres well to the adherend, and does not easily peel off from the adherend when the extensible pressure-sensitive adhesive sheet is removed. It is more preferable that the SUS adhesive strength is 5 N / 20 mm or more (for example, 6 N / 20 mm or more, typically 6.5 N / 20 mm or more). The upper limit of the SUS adhesive force is not particularly limited, but is preferably less than 15 N / 20 mm (for example, less than 12 N / 20 mm, typically less than 10 N / 20 mm) from the viewpoint of removability from the adherend.

  The measurement of the SUS adhesive force can be performed by the following method. An extension aid film cut to a size of 20 mm in width and 100 mm in length is prepared. Under an environment of 23 ° C. and 50% RH, the adhesive surface of the stretch assisting film is exposed, and the adhesive surface is pressed against the surface of the SUS plate by reciprocating a 2 kg roller once. After leaving it for 30 minutes in the same environment, the peel strength [N / 20 mm width] under the conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees using a tensile tester according to JIS Z 0237: 2000. Is measured. As the tensile tester, a universal tensile / compression tester (product name “TG-1kN”, manufactured by Minebea) can be used.

(Resin base material)
As the resin base material that can constitute the stretch assisting film, various film-like resin base materials that can assist the elongation of the pressure-sensitive adhesive sheet when the extensible pressure-sensitive adhesive sheet is removed can be used. As the base material, for example, a non-foamed resin film is preferable. Non-foamed resin films tend to have excellent mechanical strength such as tensile strength. The non-foamed resin film is also excellent in workability, dimensional stability, thickness accuracy, economy (cost), and the like.

Preferred examples of the resin substrate disclosed herein include an olefin-based resin film. Examples of the resin material constituting the olefin-based resin film include polyolefins such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, and ethylene-butene copolymer. Examples of PE include high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultrahigh-molecular-weight polyethylene (UHPE), and the like. Above all, ultrahigh molecular weight polyethylene is more preferable from the viewpoint of making the dynamic friction coefficient on the back surface of the stretching assist film equal to or less than a predetermined value. The above resin materials can be used alone or in combination of two or more. The content of the olefin-based resin in the olefin-based resin film is usually about 50% by weight or more and 80% by weight or more (typically 90% by weight or more, for example, 95 to 100% by weight; the same applies hereinafter). Is appropriate. The resin base material according to a particularly preferred embodiment is mainly composed of ultra-high molecular weight polyethylene (a component most contained in the resin film; usually 50% by weight or more (preferably 80% by weight or more, typically 90% by weight). As described above, for example, an ultra-high molecular weight polyethylene film containing 95 to 100% by weight). The ultrahigh molecular weight polyethylene refers to a polyethylene having a weight average molecular weight of 50 × 10 ⁴ or more (typically 100 × 10 ⁴ or more, for example, 100 × 10 ^{4 to} 700 × 10 ⁴ ).

  Another preferred example of the resin substrate disclosed herein is a fluorine-based resin film. Examples of the resin material constituting the fluororesin film include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene. -Tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF) and the like. Among them, PTFE and PFA are more preferable from the viewpoint of setting the dynamic friction coefficient on the back surface of the stretching assist film to a predetermined value or less. The above resin materials can be used alone or in combination of two or more. The content of the fluorine-based resin in the fluorine-based resin film is usually about 50% by weight or more, and is preferably 80% by weight or more (typically 90% by weight or more, for example, 95 to 100% by weight). is there. The resin substrate according to one particularly preferred embodiment is a fluorine-based resin film containing PTFE and / or PFA as a main component.

  When the resin substrate has a multilayer structure, the layer constituting the back surface of the extension assisting film is the olefin resin film (olefin resin layer) or the fluorine resin film (fluorine resin layer). Is preferred. In that case, the layer other than the layer constituting the back surface in the resin base material may be a resin layer composed of various resin materials. Examples of the resin material constituting such a layer include, in addition to the olefin-based resin and the fluorine-based resin, polyesters such as PET and PBT; polyvinyl chloride; polyimide; polyphenylene sulfide; ethylene-vinyl acetate copolymer; polyurethane; Polyamide; and the like. The above resin materials can be used alone or in combination of two or more.

  In the resin base material, if necessary, fillers (inorganic fillers, organic fillers, etc.), colorants (pigments, dyes), antioxidants, antioxidants, ultraviolet absorbers, antistatic agents, lubricants, Various additives such as a plasticizer and a stabilizer may be blended. The mixing ratio of the various additives is usually less than 30% by weight (for example, less than 20% by weight, typically less than 10% by weight).

  The resin substrate may have a single-layer structure, a two-layer structure, a three-layer structure or a multi-layer structure of more layers. The method for producing the resin substrate (typically, a film-shaped resin substrate) is not particularly limited as long as a conventionally known method can be appropriately employed. For example, a resin substrate prepared by appropriately employing a conventionally known general film forming method such as extrusion molding, inflation molding, T-die cast molding, and calendar roll molding can be used.

  Even if a conventionally known surface treatment such as a corona discharge treatment, a plasma treatment, an ultraviolet irradiation treatment, an acid treatment, an alkali treatment, or the application of a primer is applied to the surface of the resin substrate (the surface of the pressure-sensitive adhesive layer). Good. Such a surface treatment may be a treatment for improving the adhesion between the resin substrate and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer to the substrate.

  The thickness of the resin substrate is not particularly limited, and can be appropriately selected depending on the purpose. Usually, it is appropriate that the thickness is 1 μm or more, and it is preferably about 5 μm or more (for example, 7 μm or more, typically 10 μm or more). The resin substrate having the above thickness tends to have sufficient strength to protect the end of the adherend. In a preferred embodiment, the thickness of the resin substrate is 20 μm or more. By making the thickness of the resin base material more than a predetermined value, the thickness of the stretch assisting film also tends to increase. For example, the stretch assisting film is attached to a corner of an adherend (for example, a corner having a substantially right angle or an acute angle). When attached, R corresponding to the thickness is formed on the outer surface of the stretch assisting film, so that smoother peeling is possible. In addition, the deformation and breakage of the adherend and the shredding of the extensible pressure-sensitive adhesive sheet tend to be more preferably prevented. From such a viewpoint, the thickness is preferably 30 μm or more (for example, 50 μm or more). Further, the thickness of the resin substrate is suitably set to 1000 μm or less (for example, 500 μm or less). The thickness of the resin substrate is preferably 300 μm or less, more preferably 200 μm or less (for example, 150 μm or less, typically 120 μm or less). The stretch assisting film in which the thickness of the base material is limited to a predetermined value or less does not prevent the joining by the stretchable pressure-sensitive adhesive sheet and does not prevent the smooth peeling of the stretchable pressure-sensitive adhesive sheet at the time of removal. In addition, by limiting the thickness of the resin base material, even in the case of bending and pasting, such as in the case of sticking to a corner portion of an adherend, good curved surface adhesiveness is obtained regardless of the type of resin base material. Easy to obtain.

(Adhesive layer)
Examples of the pressure-sensitive adhesive layer (pressure-sensitive adhesive) that can constitute the extension assisting film include an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyether-based pressure-sensitive adhesive, which are known in the field of pressure-sensitive adhesives. Various pressure-sensitive adhesives such as a silicone-based pressure-sensitive adhesive, a polyamide-based pressure-sensitive adhesive, and a fluorine-based pressure-sensitive adhesive can be used. The pressure-sensitive adhesive layer of the stretch assisting film disclosed herein is preferably an acrylic pressure-sensitive adhesive layer containing an acrylic polymer as a base polymer, or a silicone pressure-sensitive adhesive layer containing a silicone-based polymer as a base polymer.

  The pressure-sensitive adhesive layer may contain a tackifier, a leveling agent, a cross-linking agent, a cross-linking aid, a plasticizer, a softener, a filler, a colorant (dye or pigment), an antistatic agent, an antioxidant, if necessary. It may contain various additives commonly used in the field of pressure-sensitive adhesives, such as an ultraviolet absorber, an antioxidant, a light stabilizer, and a dispersant. As for such various additives, conventionally known ones can be used in a conventional manner, and do not particularly characterize the present invention, and thus detailed description thereof will be omitted. In addition, a method for forming the pressure-sensitive adhesive layer may be the same as the method for forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet, and thus a detailed description thereof will be omitted.

  The thickness of the pressure-sensitive adhesive layer that can constitute the stretch assisting film is not particularly limited, and can be appropriately selected depending on the purpose. Usually, the thickness of the pressure-sensitive adhesive layer is suitably 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and further more preferably 5 μm or more from the viewpoint of adhesive performance and the like. The thickness is suitably 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and still more preferably 80 μm or less from the viewpoint of productivity such as drying efficiency.

(Thickness of stretching aid film)
The total thickness of the stretch assisting film disclosed herein is not particularly limited, but is preferably about 1 μm or more (for example, 2 μm or more), and more preferably about 1000 μm or less. In addition, the total thickness of the stretch assisting film is preferably about 300 μm or less, since it does not hinder the joining by the stretch adhesive sheet and does not hinder smooth peeling when removing the stretch adhesive sheet. In one preferred embodiment, the total thickness of the stretch assisting film is less than 230 μm. Thereby, excellent peelability is realized. The total thickness is more preferably 200 μm or less, further preferably 160 μm or less, and particularly preferably 150 μm or less (for example, 140 μm or less). From the same viewpoint, the extension assisting film is preferably thinner than the extensible pressure-sensitive adhesive sheet. With this configuration, when the extensible pressure-sensitive adhesive sheet is pulled out, the extensible pressure-sensitive adhesive sheet is less likely to be caught on the end of the stretch assisting film, and excellent peelability is realized. In addition, by limiting the thickness of the extension assisting film, even in the case of bending and pasting, such as in the case of pasting to the corner of the adherend, good curved surface adhesion can be achieved regardless of the type of resin base material. Easy to obtain. In addition, when providing a thickness reduction part in an extension assistance film, the total thickness of an extension assistance film is not specifically limited. Further, the total thickness of the stretching assist film is preferably about 5 μm or more (for example, 10 μm or more) from the viewpoint of strength and the like. In a preferred embodiment, the total thickness of the stretching assist film is 30 μm or more. By making the total thickness of the extension assisting film equal to or more than a predetermined value, R corresponding to the thickness when the extension assisting film is attached to a corner of the adherend (for example, a corner having a substantially right angle or an acute angle) It is formed on the outer surface of the stretching assist film, and enables smoother peeling. In addition, the deformation and breakage of the adherend and the shredding of the extensible pressure-sensitive adhesive sheet tend to be more preferably prevented. From such a viewpoint, the total thickness is preferably 50 μm or more, more preferably 80 μm or more, further preferably 100 μm or more, and particularly preferably 120 μm or more.

  The stretch assisting film having the above configuration may be manufactured to have an appropriate performance and size based on the common general technical knowledge of those skilled in the art, or a commercially available product may be obtained.

<Application>
The releasable adhesive set disclosed herein is not particularly limited, but examples thereof include metal materials such as stainless steel (SUS) and aluminum; inorganic materials such as glass and ceramics; nylon, polycarbonate (PC), and polymethyl methacrylate ( PMMA), polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI), and other resin materials; rubber materials such as natural rubber and butyl rubber; and composite materials of these materials. Can be used. The adherend surface made of these materials generally has a coefficient of kinetic friction of more than 0.20. A polymer battery as an adherend to be described later is, for example, printed on the surface of a PET case, and can exhibit a larger dynamic friction coefficient. For an adherend having a surface having a relatively large dynamic friction coefficient (for example, more than 0.20, or even 0.25 or more) as described above, the removable adhesive set disclosed herein is preferably used. .

  The releasable adhesive set disclosed herein can smoothly perform peeling from an adherend (typically, peeling by pulling). In addition, deformation and breakage of the adherend are prevented, and the extensible pressure-sensitive adhesive sheet is difficult to cut. Taking advantage of this feature, it is preferably used as an adhesive means for various uses that can be peeled off after attaching. For example, for fixing a protection panel (lens) that protects the display unit of electronic equipment, fixing a decoration panel of a display (for example, a display of a television), fixing a battery pack of a personal computer, and waterproofing a lens of a digital video camera. The removable adhesive set disclosed herein can be employed. Above all, it is preferably used as a removable adhesive set for portable electronic devices that require a certain degree of adhesive strength at the time of use, while requiring smooth removal during repair, replacement, inspection, recycling, etc. of constituent members. be able to. For example, mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, a wrist wear type to be worn on the wrist like a wristwatch, a modular type to be worn on a part of the body with clips or straps, a glasses type) (Eyewear type including monocular type and binocular type, including head mounted type), clothing type attached to shirts, socks, hats, etc. in the form of accessories, earwear type attached to ears like earphones, etc.), Digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game devices, electronic dictionaries, electronic notebooks, electronic books, in-vehicle information devices, portable radios, portable TVs, portables In portable electronic devices such as printers, portable scanners, and portable modems, protect the display Protective panel (lens) fixing, key module member fixing, rim sheet fixing, decoration panel fixing, battery fixing, and other various members (circuit boards, various panel members, buttons, lighting equipment members, internal camera members, heat dissipating materials, graphite sheets) And fixing of display objects (including various marks) such as logos (design letters) and various designs. In the removable adhesive set disclosed herein, the extensible pressure-sensitive adhesive sheet exhibiting a predetermined or higher adhesive strength, when used in the portable electronic device, the impact when the portable electronic device falls. Thus, the fixed arrangement of the adherend member can be maintained. This is particularly advantageous in battery fastening applications. This is because a battery to be fixed can expand due to use over time, and therefore a gap is provided around the battery, and fixing failure (peeling off of the adhesive sheet) due to a drop impact or the like tends to be a significant defect. . In this specification, “portable” means that it is not enough to simply carry a portable device, and that an individual (standard adult) has a level of portability that can be relatively easily carried. Shall mean.

  Further, the removable adhesive set having excellent pull-out property is suitable as a removable adhesive set used for fixing a battery (including a primary battery and a secondary battery; for example, a polymer battery) in a portable electronic device. is there. The battery is usually placed in a place that needs to be removed when repairing, replacing, inspecting, or the like, a component (including the battery) of the portable electronic device. Therefore, the adhesive sheet for fixing the battery frequently needs to be removed. However, removing the battery by physical means such as use of a removal tool, manual peeling, and heating may damage the battery and may be undesirable in terms of safety. The reduction of the peeling force by light curing is not effective because the irradiation is performed through the battery because of the location of the adhesive sheet. The releasable adhesive set disclosed herein exerts the function of fixing the battery well, and uses the above-described pull-out (typically, pull-out) method when removing the battery after the end of its use. Utilization allows easy removal. The above removable adhesive set is particularly preferable as a removable adhesive set used for fixing a polymer battery. Polymer batteries tend to be more deformable than other types of batteries (typically batteries with metal cases), so conventional peeling methods can deform the battery and impair its functionality. there were. According to the removable adhesive set disclosed herein, it is possible to effectively remove the stretchable adhesive sheet while suppressing the deformation of the polymer battery by using the above-described pull-out (typically, pull-out) method. Can be.

  In addition, when the stretchable adhesive sheet used for fixing the battery of the portable battery device cannot be pulled in parallel with the shearing direction at the time of removal due to other parts existing around the battery or the arrangement of the battery, etc. There are many. In such a case, the extensible pressure-sensitive adhesive sheet is removed by being pulled at a non-parallel angle to the adhesive surface (for example, an angle of 45 to 90 degrees, typically 70 to 90 degrees). In the removal, there is a possibility of damage due to contact with an adherend (battery) or an obstacle. According to the removable adhesive set disclosed herein, even in such a removal mode, the extensible pressure-sensitive adhesive sheet can be preferably removed without being damaged.

  Furthermore, the removable adhesive set having excellent pull-out property (typically, pull-out property) is attached to a wall surface, a pillar, furniture, a household electrical appliance, a glass surface, etc., and after being used for a predetermined period, is replaced. It is also suitable as a releasable adhesive set used for fixing an article or a part (an adherend, an object to be fixed, an object to be attached, etc.) to be obtained. Also in this application, while fixing the article etc., the extensible pressure-sensitive adhesive sheet constituting the removable adhesive set exhibits a good fixing function, and when removing the article etc., it is provided on the extensible pressure-sensitive adhesive sheet. By removing the entirety of the pressure-sensitive adhesive sheet by grasping the tab or the like, removal of the pressure-sensitive adhesive sheet (for example, removal in the direction of the arrow in FIG. 6C) can be performed efficiently.

  Hereinafter, tests relating to the present invention will be described, but the present invention is not intended to be limited to those shown in the tests. In the following description, “parts” and “%” are based on weight unless otherwise specified.

<Preparation of extensible adhesive sheet>
In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas inlet tube, a reflux condenser, and a dropping funnel, 100 parts of BA, 5 parts of VAc, 3 parts of AA, 0.1 part of HEA, and 0.2 part of AIBN as a polymerization initiator. And toluene as a polymerization solvent were charged, and solution polymerization was performed at 60 ° C. for 6 hours to obtain a toluene solution of an acrylic polymer. Mw of this acrylic polymer was 55 × 104.
For 100 parts of the acrylic polymer contained in the toluene solution, 40 parts of a polymerized rosin ester resin (manufactured by Arakawa Chemical Industries, product name “Pencel D-125”, softening point 125 ° C.) as a tackifier resin, and an isocyanate-based resin 2 parts of a crosslinking agent (manufactured by Nippon Polyurethane Industry Co., product name "Coronate L") and 30 parts of aluminum hydroxide particles (manufactured by Showa Denko KK, product name "Heidilite H-32") as filler particles were added. By mixing, an acrylic pressure-sensitive adhesive composition was prepared. The filler particles used have an average particle diameter of 8 μm, and a percentage of particle diameters of less than 25 μm is 85% or more and a percentage of particles having a particle diameter of less than 1 μm is 3%.
Two commercially available release liners (trade name “SLB-80W3D”, manufactured by Sumika Kagaku) were prepared. The pressure-sensitive adhesive composition was applied to one surface (release surface) of each of the release liners so that the thickness after drying was 25 μm, and dried at 100 ° C. for 2 minutes. Thus, the pressure-sensitive adhesive layers (first pressure-sensitive adhesive layer and second pressure-sensitive adhesive layer) were respectively formed on the release surfaces of the two release liners.
A non-foamed ether-based polyurethane resin film having a thickness of 100 μm (trade name “Esmer URS ET-N”, manufactured by Nippon Matai Co., Ltd., breaking strength: 73 to 74 MPa, elongation at break: 506 to 507%, 5% modulus as a film-shaped substrate) 1.6 MPa, 150% modulus 6.4-6.5 MPa) were prepared. The pressure-sensitive adhesive layers formed on the two release liners were bonded to both surfaces of the film-shaped substrate. The release liner was left on the pressure-sensitive adhesive layer as it was and used for protecting the surface (pressure-sensitive surface) of the pressure-sensitive adhesive layer. The obtained structure was passed through a laminator (0.3 MPa, speed 0.5 m / min) at 80 ° C. once, and then aged in an oven at 50 ° C. for 1 day. The obtained double-sided pressure-sensitive adhesive sheet was cut into a belt shape having an appropriate width, and a plurality of extensible pressure-sensitive adhesive sheets having the same shape and the same size were produced.

[Pullability evaluation test]
Eight types of extension assisting films having different resin substrate types and thicknesses were prepared. The stretching aid film is formed by applying a silicone-based adhesive on one surface of a polytetrafluoroethylene (PTFE) resin film substrate, or is formed by applying an acrylic adhesive on one surface of an ultra-high molecular weight polyethylene (UHPE) resin film substrate. It is formed by applying an agent. After fixing the stretch assisting film so as to cover the corner 80C (almost right angle) of the object 80 as shown in FIG. 3, the object 80 and the object 90 are formed as shown in FIG. And so that the adhesive area becomes constant. Then, in the joining, a part (a part of a certain area) of the extensible pressure-sensitive adhesive sheet 10 was exposed so as to protrude from between the object 80 and the object 90. The exposed portion was gripped, and as shown in FIG. 3, a pull-out operation (hand peeling) was performed at a pull-out angle of about 90 degrees (the direction of the arrow in the drawing), and the pull-out property was evaluated based on the following three criteria.
：: The extensible pressure-sensitive adhesive sheet could be pulled out smoothly.
：: The extensible pressure-sensitive adhesive sheet could be pulled out smoothly, but a pulling force was required as compared with ◎.
X: The extensible pressure-sensitive adhesive sheet could not be pulled out smoothly.
Table 1 shows the thickness of the stretch assisting film and the results of the pull-out evaluation test. Table 1 also shows the resin base material type and the thickness of the extension assisting film.

  As described above, the specific examples of the present invention have been described in detail. However, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above. When there are a plurality of embodiments, the configurations described in the different embodiments can be appropriately combined. Therefore, embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention.

The matters disclosed by this specification include the following.
(1) A double-sided adhesive extensible pressure-sensitive adhesive sheet for joining one object and another object, and an extension assisting film provided at an end of a surface to be adhered of one of the one object and the other object And wherein the thickness of the stretch assisting film is less than 230 μm.
(2) A double-sided adhesive extensible pressure-sensitive adhesive sheet for joining one object and another object, and an extension auxiliary film provided at an end of a surface to be adhered of one of the one object and the other object A set comprising: a stretch assisting film having a portion whose thickness decreases toward an end.
(3) The set according to (1) or (2), wherein the coefficient of kinetic friction on the back surface of the stretching assist film is 0.20 or less.
(4) The set according to any one of (1) to (3), wherein the extensible pressure-sensitive adhesive sheet exhibits a shear adhesive force of 0.5 to 5 MPa.
(5) The above-mentioned (1) to (4), wherein the extensible pressure-sensitive adhesive sheet includes an adhesive portion that joins the one object and the other object, and an exposed portion that protrudes from between the joined objects. ).
(6) The adhesive portion of the extensible pressure-sensitive adhesive sheet,
The one object and the other object can be extended by pulling the exposed portion in a state where the one object and the other object are joined with the adhesive portion, and the one object and the other object can be extended by the extension. The set according to (5), wherein the set is configured to be released.
(7) The extensible pressure-sensitive adhesive sheet and the elongation-assisting film have a strip shape extending linearly,
The stretch assist film is arranged so that its longitudinal direction intersects with the longitudinal direction of the extensible pressure-sensitive adhesive sheet,
The set according to any one of (1) to (6), wherein the length of the stretch assisting film is equal to or longer than the width of the stretchable pressure-sensitive adhesive sheet.
(8) The set according to any one of (1) to (7), wherein the extensible pressure-sensitive adhesive sheet includes a plurality of pressure-sensitive adhesive sheet pieces arranged at intervals.
(9) The above-mentioned (1) to (8), wherein the extension auxiliary film includes a resin base constituting a back surface of the extension auxiliary film, and an adhesive layer provided on one surface of the resin base. The set described in any of them.
(10) The set according to (9), wherein in the extension assisting film, the resin substrate is a fluororesin film or an ultrahigh molecular weight polyethylene film.
(11) The set according to any one of (1) to (10), wherein the extension assisting film has a thickness of 150 μm or less.
(12) The extensible pressure-sensitive adhesive sheet is pulled at an angle of 45 ° or more with respect to a joint surface between the one object and the other object from a state where the one object and the other object are joined. Is capable of releasing the joined state between the one object and the other object, and is configured to be removed from between the one object and the other object. The set according to any one of 1) to (11).
(13) The set according to any one of (1) to (12) above, which is used for fixing a battery of a portable electronic device.
(14) The set according to any one of (1) to (13), wherein a tab is provided at an end of the extensible pressure-sensitive adhesive sheet.

(15) The extensible pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer,
The pressure-sensitive adhesive layer contains an acrylic polymer in a proportion exceeding 50% by weight of a polymer component contained in the pressure-sensitive adhesive layer,
The acrylic polymer has the following formula (1) as a monomer component:
CH ₂ ＣC (R ¹ ) COOR ² (1)
(In the above formula (1), R ¹ is a hydrogen atom or a methyl group. R ² is a linear alkyl group having 1 to 20 carbon atoms.) The set according to any one of the above (1) to (14), which contains 70% by weight or more.
(16) The alkyl (meth) acrylate is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s -Butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate , Nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate , Tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate and eicosyl (meth) acrylate The set according to the above (15), wherein the set is at least one selected from the group consisting of:
(17) The acrylic polymer further contains a functional group-containing monomer as the monomer component,
The functional group-containing monomer includes acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 4 The set according to (15) or (16), wherein the set is at least one selected from the group consisting of -hydroxybutyl (meth) acrylate.
(18) The pressure-sensitive adhesive layer contains a tackifier resin having a softening point of 100 ° C. or higher,
The set according to any one of (15) to (17), wherein the tackifier resin includes at least one of a rosin-based tackifier resin and a terpene-based tackifier resin.
(19) The set according to any of (15) to (18), wherein the pressure-sensitive adhesive layer contains 10 to 60 parts by weight of a tackifier based on 100 parts by weight of the acrylic polymer.
(20) The set according to any of (15) to (19), wherein the pressure-sensitive adhesive layer contains an acrylic oligomer.
(21) The pressure-sensitive adhesive layer contains filler particles,
The filler particles include aluminum, chromium, iron, stainless steel, aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, zinc oxide, tin oxide, copper oxide, nickel oxide, aluminum hydroxide, boehmite, magnesium hydroxide, and calcium hydroxide. , Zinc hydroxide, silicic acid, iron hydroxide, copper hydroxide, barium hydroxide, zirconium oxide hydrate, tin oxide hydrate, basic magnesium carbonate, hydrotalcite, dawsonite, borax, zinc borate, silicon carbide (15) to (15) to which are at least one selected from the group consisting of boron carbide, nitrogen carbide, calcium carbide, aluminum nitride, silicon nitride, boron nitride, gallium nitride, calcium carbonate, barium titanate and potassium titanate. The set according to any one of (20).
(22) The film according to any of the above (15) to (21), further comprising a film-shaped substrate supporting the pressure-sensitive adhesive layer, wherein the film-shaped substrate is a resin film substrate having an expansion ratio of less than 1.1 times. The set described in any of them.
(23) The film-like substrate according to (22), wherein the film-like substrate includes at least one resin material selected from the group consisting of polyurethane, urethane (meth) acrylate-based polymer, polyolefin, polyester, and polyvinyl chloride. set.
(24) The film-shaped substrate contains polyurethane in a proportion of 70% by weight or more,
The set according to (22) or (23), wherein the polyurethane is an ether-based polyurethane, an ester-based polyurethane, or a carbonate-based polyurethane.

(25) A method of joining one object and another object in a separable manner,
Providing a stretchable adhesive sheet and a stretch assisting film;
Attaching the stretch assisting film to an end of the object to be bonded of one of the one object and the other object;
Attaching the adhesive portion of the extensible pressure-sensitive adhesive sheet to the one object and the other object;
Including
The stretch assisting film is, at the time of removal of the stretch adhesive sheet, when the stretch adhesive sheet is pulled at an angle that is non-parallel to the joining surface of the object, the stretch adhesive sheet at the end of the adhered surface. The joining method is arranged so as to contact with.
(26) The method according to (25), wherein the thickness of the extension assisting film is less than 230 μm.
(27) The method according to (25) or (26), wherein the extension assisting film has a portion whose thickness decreases toward an end.
(28) A method for releasing the joining between one object and another object joined by an extensible adhesive sheet,
The extensible pressure-sensitive adhesive sheet has an adhesive portion joining the one object and the other object, and an exposed portion protruding from between the joined objects,
The method includes a step of pulling the exposed portion in a state where the one object and the other object are joined with the extensible adhesive sheet interposed therebetween,
An extension assisting film is attached in advance to an end of the adhered surface of one of the one object and the other object,
The stretch assisting film is arranged to be in contact with the extensible pressure-sensitive adhesive sheet at the end of the surface to be adhered when the extensible pressure-sensitive adhesive sheet is pulled at a non-parallel angle with respect to the joining surface of the object. There is a debonding method.
(29) The method according to (28), wherein the thickness of the extension assisting film is less than 230 μm.
(30) The method according to (28) or (29), wherein the extension assisting film has a portion whose thickness decreases toward an end.

1, 2, 3 sets (removable adhesive set)
10, 110, 210 Stretchable adhesive sheet 12 Adhesive part 14 Exposed part 50, 150, 250, 350 Extension aid film 50A, 250A, 350A Adhesive face (of extension aid film) 50B, 250B, 350B Back of (stretch assistance film) 80,180 One object 80A, 180A Adhered surface 80B Adjacent side surface 80C Corner 90,190 Other object 220 Film-like base material 231,232 Adhesive layer 260 Resin base material 270 Adhesive layer 352 Thickness reduced portion

Claims (13)

A double-sided adhesive extensible pressure-sensitive adhesive sheet that joins one object and another object, and a stretching auxiliary film provided at the end of the adhered surface of one of the one object and the other object, Prepared,
The thickness of the stretching auxiliary film is less than 230 μm,
A set, wherein the extensible pressure-sensitive adhesive sheet is composed of a plurality of pressure-sensitive adhesive sheet pieces arranged at intervals .   The set according to claim 1, wherein the coefficient of kinetic friction of the back surface of the stretch assisting film is 0.20 or less.   The set according to claim 1, wherein the extensible pressure-sensitive adhesive sheet exhibits a shear adhesive strength of 0.5 to 5 MPa.   The stretchable pressure-sensitive adhesive sheet has an adhesive portion that joins the one object and the other object, and an exposed portion that protrudes from between the joined objects, any one of claims 1 to 3. The set described in. The adhesive portion of the extensible pressure-sensitive adhesive sheet,
The one object and the other object can be extended by pulling the exposed portion in a state where the one object and the other object are joined with the adhesive portion, and the one object and the other object can be extended by the extension. The set according to claim 4, wherein the set is configured to be released. The extensible pressure-sensitive adhesive sheet and the stretch assisting film have a band shape extending linearly,
The stretch assist film is arranged so that its longitudinal direction intersects with the longitudinal direction of the extensible pressure-sensitive adhesive sheet,
The set according to any one of claims 1 to 5, wherein a length of the extension assisting film is equal to or longer than a width of the extensible pressure-sensitive adhesive sheet. The stretch assisting film according to any one of claims 1 to 6 , further comprising: a resin base constituting a back surface of the stretch assisting film; and an adhesive layer provided on one surface of the resin base. Set. The set according to claim 7 , wherein in the extension assisting film, the resin substrate is a fluororesin film or an ultrahigh molecular weight polyethylene film. The set according to any one of claims 1 to 8 , wherein the extension assisting film has a thickness of 150 µm or less. The stretchable pressure-sensitive adhesive sheet, by pulling at an angle of 45 ° or more with respect to a bonding surface between the one object and the other object from a state where the one object and the other object are bonded, it is possible to release the bonding state between the one object and said other objects are and configured to be removed from between the one object and said other object, according to claim 1-9 A set according to any one of the preceding claims. The set according to any one of claims 1 to 10 , which is used for fixing a battery of a portable electronic device. A method of joining one object and another object in a separable manner,
Providing a stretchable adhesive sheet and a stretch assisting film;
Attaching the stretch assisting film to an end of the object to be bonded of one of the one object and the other object;
Attaching the adhesive portion of the extensible pressure-sensitive adhesive sheet to the one object and the other object;
Including
The stretch assisting film is, at the time of removal of the stretch adhesive sheet, when the stretch adhesive sheet is pulled at an angle that is non-parallel to the joining surface of the object, the stretch adhesive sheet at the end of the adhered surface. Are arranged to contact the
The thickness of the stretching auxiliary film is less than 230 μm,
The joining method , wherein the extensible pressure-sensitive adhesive sheet is composed of a plurality of pressure-sensitive adhesive sheet pieces arranged at intervals . A method for releasing the joining between one object and another object joined by an extensible adhesive sheet,
The extensible pressure-sensitive adhesive sheet has an adhesive portion joining the one object and the other object, and an exposed portion protruding from between the joined objects,
The method includes a step of pulling the exposed portion in a state where the one object and the other object are joined with the extensible adhesive sheet interposed therebetween,
An extension assisting film is attached in advance to an end of the adhered surface of one of the one object and the other object,
The stretch assisting film is arranged to be in contact with the extensible pressure-sensitive adhesive sheet at the end of the surface to be adhered when the extensible pressure-sensitive adhesive sheet is pulled at a non-parallel angle with respect to the joining surface of the object. Yes,
The thickness of the stretching auxiliary film is less than 230 μm,
The method for releasing bonding , wherein the extensible pressure-sensitive adhesive sheet includes a plurality of pressure-sensitive adhesive sheet pieces arranged at intervals .

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