JP6521538B2 - Anisotropic adhesive sheet - Google Patents

Description

  The present invention relates to an anisotropic pressure-sensitive adhesive sheet which can exhibit different releasability depending on the releasable direction, and can achieve both strong adhesiveness in a specific direction and excellent releasability in a direction other than the specific direction. .

Adhesive products such as pressure sensitive adhesive sheets and pressure sensitive adhesive tapes are used in many applications. It is general to select and use an adhesive having an appropriate adhesive strength in accordance with the use application. In applications where permanent adhesion is to be performed, a tacky adhesive is used, and in applications to be peeled off, a tacky adhesive is generally used. However, in products such as wallpaper, window films, and marking sheets, an adhesive with high adhesive strength is required. However, when the attachment position is corrected, when bubbles or foreign matter get stuck during adhesion, and adhesion At the time of product replacement, etc., it is required to simultaneously satisfy the contradictory function of wanting to be easily peeled off. In addition, there is also a problem that the adhesive remains on the adherend when the patch, the seal, and various adhesive tapes are removed when unnecessary. Furthermore, with regard to packaging containers such as cardboard boxes and envelopes to which an address label, an invoice of a home delivery service, etc. have been attached, conventionally, it has been general to dispose of the address label etc. while adhering. However, for the purpose of preventing leakage of personal information, etc., it is required to easily peel off a portion where personal information such as an address label is described and discard a packaging container such as a cardboard box.
On the other hand, optical films, protective films for displays, protective sheets for metal plates and steel plates, etc. can be used without peeling when used by bonding to adherends, and can be easily peeled from adherends when unnecessary. There is a need for a pressure-sensitive adhesive sheet (which is lightly peeled off). That is, there is a need for a pressure-sensitive adhesive product which adheres firmly to an adherend and which can be easily peeled off from the adherend when it is not needed or at the time of bonding correction in applications where permanent adhesion is made and applications where it is re-peeled. There is.

  Various proposals have been made conventionally for achieving both adhesiveness and releasability. For example, Patent Document 1 proposes a heat-peelable pressure-sensitive adhesive sheet in which adhesion is reduced or lost by heat treatment, in which a foaming agent-containing pressure-sensitive adhesive layer is provided on a substrate. Further, Patent Document 2 proposes a pressure-sensitive adhesive tape which cures a pressure-sensitive adhesive by irradiation of radiation and significantly reduces the adhesion. However, such a pressure-sensitive adhesive sheet has a problem that the function of light peeling can not be utilized where the ultraviolet irradiation device or the heating device is not installed.

  In addition, some pressure-sensitive adhesive sheets having different adhesion depending on the peeling direction have been proposed. For example, Patent Document 3 proposes a pressure-sensitive adhesive product using a partially oriented and crystallized elastomer. Patent Document 4 introduces an anisotropic releasable pressure-sensitive adhesive tape in which anisotropically shaped rigid particles and / or fibers are oriented and dispersed in at least one layer of a substrate and / or a pressure-sensitive adhesive layer. Although these proposals do not require equipment and equipment for utilizing the light peeling function, and the workability is excellent, the characteristics of the pressure sensitive adhesive are limited because the material of the pressure sensitive adhesive is limited to a specific substance. There is a problem that the range is limited.

  Further, Patent Document 5 proposes an anisotropic adhesive molded article using a support having anisotropic flexibility. The use of a substrate with anisotropic flexibility, and the material of the adhesive itself is not limited to a specific substance, so that there is an advantage that the characteristic range of the adhesive is not limited, but the structure of the substrate is There was a problem of being limited.

Japanese Utility Model Publication No. 50-013878 Japanese Patent Application Laid-Open No. 60-196956 Unexamined-Japanese-Patent No. 2000-502379 JP 2004-189847 A JP-A-7-018227

The present invention has been made in view of the above circumstances, and provides a pressure-sensitive adhesive sheet which adheres firmly to an adherend and which can be easily peeled off from the adherend when it is not needed or when the bonding is corrected. is there.
More specifically, the present invention exhibits anisotropic releasability depending on the direction of exfoliation, so that anisotropic adhesion can achieve both strong adhesiveness in a specific direction and excellent releasability in a direction other than the specific direction. It is an issue to provide a sex sheet.

  As a result of earnestly examining in order to solve this subject, the adhesive force of an adhesive sheet is provided by providing a resin layer between a base material and an adhesive layer, and providing a concavo-convex structure on the surface in contact with the adhesive layer of a resin layer. Was found to change. In addition, it has been found that by giving anisotropy to the pattern of the concavo-convex structure on the surface of the resin layer, a pressure-sensitive adhesive sheet in which the peeling force (adhesive force) differs depending on the peeling direction can be obtained, and the present invention has been completed.

To solve the above problems, the present invention is, on at least one surface of a long base material, the resin layer is formed to have a cross section of the concavo-convex structure, a resin layer having a cross-section of the relief structure in the adhesive layer In the pressure-sensitive adhesive sheet to be filled , the pattern shape of the concavo-convex structure of the resin layer having the cross section of the concavo-convex structure is (a) having convex portions in the form of stripes in the longitudinal direction or width direction of the substrate It is formed by having flat recesses in the form of stripes, or (b) having protrusions in the form of stripes in the oblique direction with respect to the longitudinal direction of the base material and having flat recesses in the form of stripes. The thickness T2 of the thickest portion of the pressure-sensitive adhesive layer is 5 to 100 μm, and the ratio K of the thickness T1 of the thinnest portion to the thickness T2 of the thickest portion of the thickness of the pressure-sensitive adhesive layer There is a K = T1 / T2 = 0.2~0.8, the adhesive The surface to be adhered to an adherend layer, the arithmetic average surface roughness Ra is not more 5μm or less, after stuck to the adhesive sheet to an adherend, the direction of peeling the pressure-sensitive adhesive layer from the adherend An anisotropic adhesive sheet characterized in that the adhesive strength is different .

  When the adherend is a glass plate, the ratio R between the adhesion τ1 in the direction along the convex shape of the resin layer and the adhesion τ2 in the direction orthogonal to the convex shape of the resin layer is R = Provided is an anisotropic adhesive sheet characterized by τ1 / τ2 = 0.1 to 0.5.

  The anisotropic adhesive sheet of the present invention can exhibit different releasability depending on the releasable direction, and can achieve both strong adhesiveness in a specific direction and excellent releasability in a direction other than the specific direction. As a result, it is possible to provide an anisotropic adhesive sheet which adheres firmly to the adherend and which can be easily peeled off from the adherend when it is not needed or when the bonding is corrected. In addition, the anisotropic adhesive sheet of the present invention can be used in various applications because the types of the base and the adhesive are not restricted.

(A) and (b) are each typical sectional drawing which showed an example of the anisotropic adhesive sheet of this invention. (A)-(c) is a typical perspective view showing an example of the state before laminating the pressure sensitive adhesive layer of the anisotropic adhesive sheet of the present invention, respectively. (A) And (b) is a typical sectional view showing an example of a product which used an anisotropic adhesive sheet of the present invention, respectively.

Hereinafter, the present invention will be described in detail based on the embodiments.
FIG. 1 is a schematic cross-sectional view showing the concept of the anisotropic adhesive sheet of the present invention. The anisotropic adhesive sheet 10 has a resin layer 2 formed on one surface of a substrate 1. A pressure-sensitive adhesive layer 3 is formed on the surface of the resin layer 2. The resin layer 2 has an uneven structure on the surface on the pressure-sensitive adhesive layer 3 side. In the case of FIG. 1 (a), the lower portion 2a of the resin layer 2 is continuously formed on the surface of the substrate 1, and only the upper portion 2b of the resin layer 2 has a concavo-convex structure. In the case of FIG. 1 (b), the resin layer 2 is discontinuously formed on the surface of the substrate 1, and the pressure-sensitive adhesive layer 3 can contact the surface of the substrate 1 at a location where the resin layer 2 is not formed. is there.

  The substrate 1 used for the anisotropic adhesive sheet 10 according to the present invention is not particularly limited, and a sheet of paper, a resin film, a resin sheet, a metal-containing sheet, an inorganic-containing sheet, or a sheet obtained by laminating them. You can use either. Examples of the paper base include high-quality paper, clay-coated paper, art-coated paper, resin-coated paper, glassine paper, polyethylene laminated paper and the like. Moreover, as a base material of a resin film, resin films, such as a polyethylene film, a polypropylene film, a polyester film, a polyamide film, an acrylic film, an acrylic film, a polycarbonate film, a polyimide film, a vinyl chloride film, a vinylidene chloride film, a polystyrene film, are mentioned. As a base material of a resin sheet, a polyolefin sheet, a vinyl chloride sheet, a polyester sheet, a polyamide sheet etc. are mentioned. As the metal-containing sheet, metal foil such as aluminum foil, copper foil, stainless steel foil, laminated sheet of metal foil and resin film, metal vapor-deposited sheet such as aluminum vapor-deposited sheet (may be vapor deposited film), resin containing metal particles A sheet etc. are mentioned. As an inorganic substance (compound) containing sheet | seat, the inorganic substance vapor deposition sheet (a vapor deposition film may be sufficient), such as an alumina vapor deposition sheet and a silica vapor deposition sheet, etc. are mentioned.

The material and thickness of the substrate 1 are not particularly limited, and any material and thickness may be used according to the intended use. Thus, in the present specification, the terms sheet and film may be used without particular distinction of thickness, and one term may encompass the other meaning.
In addition, in order to improve the coatability and adhesion of the resin layer 2, surface modification by corona treatment, plasma treatment, etc., as needed, on the surface of the substrate 1 on the resin layer 2 side, anchor coating agent You may give easy-adhesion processings, such as application of

  The surface of the substrate 1 opposite to the resin layer 2 may be subjected to surface treatment according to the application. For example, in the application of the adhesive tape, a release agent such as silicone may be applied to form a release agent layer. Moreover, in the application of a window film, you may form coating layers, such as a hard-coat agent, a stain prevention agent, an infrared rays (heat ray) cutting agent, and an ultraviolet-ray cutting agent. For applications such as labels, wallpaper, stickers, patches, stickers, etc., various printing layers, an image receiving layer, a protective layer, etc. may be applied.

The resin layer 2 used for the anisotropic adhesive sheet 10 concerning this invention is an important component in order to express anisotropic adhesiveness. An example of the state before laminating | stacking an adhesive layer of the anisotropic adhesive sheet of this invention was shown in FIG. In FIG. 2A, the cross-sectional shape of the upper portion 2b of the resin layer 2 has a substantially semicircular convex shape. In FIG. 2B, the cross-sectional shape of the upper portion 2b of the resin layer 2 is a convex shape having a substantially rectangular shape. In FIG. 2C, the cross-sectional shape of the upper portion 2b of the resin layer 2 has a substantially triangular convex shape. Although each figure of FIG. 2 shows the case where the lower part 2a of the resin layer 2 is continuing like FIG. 1 (a), as FIG.1 (b), the resin layer 2 is discontinuously formed. It may be
In the anisotropic adhesive sheet 10 according to the present invention, the resin layer 2 has a concavo-convex structure on the surface on the adhesive layer 3 side, and the pattern of the concavo-convex structure is anisotropic (vertically, horizontally or diagonally Pattern shape of the concavo-convex structure when different.

  The adhesive strength of the anisotropic adhesive sheet according to the present invention is the adhesive strength between the adhesive and the interface of the adherend (1) and the stress (2) required to deform the adhesive layer inside the adhesive layer. It can be considered as the sum of the The present invention is based on the concept of exerting anisotropic adhesiveness by making stress (2) required to deform the pressure-sensitive adhesive layer different according to the peeling direction. By providing a concavo-convex structure on the surface of the resin layer 2, the thickness of the pressure-sensitive adhesive layer 3 is changed, and when peeling the anisotropic adhesive sheet 10, the volume of the pressure-sensitive adhesive layer deformed by external force is changed and peeled off. There is a difference in adhesion depending on the direction. For this reason, the storage elastic modulus of the resin used for the resin layer 2 needs to be larger than the storage elastic modulus of the adhesive used for the adhesive layer 3.

  The resin used for the resin layer 2 is not particularly limited, and any resin that can form and hold a concavo-convex structure can be used. Specifically, acrylic resin, polyester resin, epoxy resin, olefin resin, polyamide resin, polyimide resin, polyvinyl alcohol resin, polyvinyl acetate resin, vinyl acetate resin, nitrocellulose (nitrocellulose), alkyd resin, phenol resin, fluorine resin, silicone resin, etc. Can be mentioned.

  A method of forming the resin layer 2 on the substrate 1 may be a known method, and a method of coating the resin paint on the substrate 1 or a method of melt-extrusion and laminating a resin on the substrate 1 (extrusion laminating method) The method (dry lamination method) etc. which produce a resin sheet beforehand, and are laminated | stacked using the base material 1 and an adhesive agent etc. are mentioned.

  In the anisotropic adhesive sheet 10 according to the present invention, the resin layer 2 has a concavo-convex structure on the surface on the adhesive layer 3 side, and the pattern of the concavo-convex structure is anisotropic (vertically, horizontally or diagonally Pattern shape of the concavo-convex structure when different. As a pattern shape of the concavo-convex structure having anisotropy, a pattern shape in which convex portions (or concave portions) are provided in a stripe shape (vertical stripe shape or horizontal stripe shape) in the flow direction or width direction of the substrate 1 made of a long film Most common. In addition, the pattern shape in which convex portions (or concave portions) are provided in the form of stripes in a diagonal direction with respect to the flow direction of the base material 1 made of a long film, or the cylindrical concave pattern is discontinuous in the longitudinal or transverse direction. And the like.

  A well-known method may be used as a method of forming the pattern of the uneven | corrugated structure which has anisotropy in the resin layer 2. FIG. For example, a method of extruding a molten resin on the substrate 1, holding the pattern by a cooling roll and transferring the pattern of the cooling roll, a method of pattern-coating a resin paint on the substrate 1 by a gravure method, a group A thermoplastic resin or an ultraviolet curing resin may be uniformly coated on the material 1, and a pattern cut die may be pressed to transfer the pattern shape to the resin surface.

  The thickness of the resin layer 2 is not particularly limited, and an appropriate thickness may be selected depending on the shape of the pattern, the depth of the concave portion of the pattern portion, the film physical properties of the adhesive, and the like. The thickness of the resin layer 2 is generally about 3 to 50 μm. If it is less than 3 μm, it is difficult to express the difference in adhesive force depending on the peeling direction, and if it exceeds 50 μm, it is disadvantageous in terms of cost and the processability of the resin layer 2 is inferior.

  In addition, on the surface of the resin layer 2 in contact with the pressure-sensitive adhesive layer 3, in order to increase the anchoring force of the pressure-sensitive adhesive layer, surface modification by corona treatment, plasma treatment, etc. or adhesion treatment such as providing an anchor coat layer You may go.

  The pressure-sensitive adhesive layer 3 used in the anisotropic pressure-sensitive adhesive sheet 10 according to the present invention adheres to the surface of the adherend, adheres firmly when in use, and can be lightly peeled off after use, or when unnecessary or correction of bonding. Is required. It is desirable that the surface of the pressure-sensitive adhesive layer 3 be smooth in order to adhere firmly in use. Specifically, the arithmetic mean surface roughness Ra of the surface of the pressure-sensitive adhesive layer 3 is preferably 5 μm or less. If the arithmetic average surface roughness Ra exceeds 5 μm, the adhesion to the adherend may be deteriorated, or air bubbles may be mixed when the anisotropic adhesive sheet 10 is bonded to the adherend.

  The type of pressure-sensitive adhesive is not particularly limited, but an pressure-sensitive adhesive according to the intended use may be used, such as an acrylic pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or a silicone-based pressure-sensitive adhesive. The thickness of the pressure-sensitive adhesive layer 3 is not particularly limited, but is often about 5 to 100 μm. If the thickness of the pressure-sensitive adhesive layer 3 is less than 5 μm, it is difficult to fill the uneven structure of the resin layer 2; if it exceeds 100 μm, there is no problem in terms of performance, but the price increases.

  Depending on the thickness of the resin layer 2, the thickness of the pressure-sensitive adhesive layer 3, and the pattern (depth, width, distance, etc. of the recesses) of the resin layer 2, the degree of anisotropic adhesiveness (direction along the convex shape of the resin layer 2) The ratio R) of the adhesive force τ1 to the adhesive force τ2 in the direction orthogonal to the convex shape of the resin layer 2 changes. In order to develop anisotropic adhesiveness, the thickness of the resin layer 2, the thickness of the pressure-sensitive adhesive layer 3, and the design of the pattern shape of the resin layer 2 are important. In the anisotropic adhesive sheet 10, the surface of the pressure-sensitive adhesive layer 3 is smooth, so the thickness of the pressure-sensitive adhesive layer 3 at the thick resin layer 2 is a portion without the resin layer 2 or the resin layer 2 is thin. It becomes thinner than the part. Anisotropic adhesiveness is expressed by the mixture of the thick part and the thin part of the adhesive layer 3. The ratio K of the thickness T1 of the thinnest portion to the thickness T2 of the thickest portion of the thickness of the pressure-sensitive adhesive layer 3 is preferably K = T1 / T2 = 0.2 to 0.8. When K is less than 0.2 and more than 0.8, anisotropic adhesion hardly occurs.

  The pressure-sensitive adhesive may be a one-component pressure-sensitive adhesive consisting of only the main agent, or a two-component pressure-sensitive adhesive consisting of a main agent and a curing agent. As necessary, adhesion improvers such as silane coupling agents, tackifiers for improving adhesion characteristics (tackifiers), antioxidants and ultraviolet absorbers for improving durability, antistatic effects You may add the antistatic agent to give, the catalyst which accelerates | stimulates a hardening reaction, the pigment for coloring of an adhesive sheet, and light-shielding provision, a filler, etc.

  As a hardening agent added to the adhesive layer 3, an isocyanate compound, an epoxy compound, a melamine compound, a metal chelate compound etc. are mentioned. Moreover, as a tackifier, rosin type, coumarone indene type, terpene type, petroleum type, phenol type etc. are mentioned.

  A known method may be used as a method of forming the pressure-sensitive adhesive layer 3. Specifically, using a known coating method such as reverse coating, comma coating, gravure coating, slot die coating, Mayer bar coating, air knife coating, etc., on a sheet on which substrate 1 and resin layer 2 are laminated. An adhesive may be applied, and then drying and curing may be performed. Depending on the type of adhesive, it may be irradiated with radiation such as ultraviolet light. Further, in order to accelerate the curing of the pressure-sensitive adhesive, aging (curing) may be performed at a predetermined temperature.

  The anisotropic adhesive sheet of the present invention is characterized in that the adhesive strength is different depending on the peeling direction. When the adherend is a glass plate, the ratio R between the adhesion τ1 in the direction along the convex shape of the resin layer 2 and the adhesion τ2 in the direction orthogonal to the convex shape of the resin layer 2 is R = It is desirable that τ1 / τ2 = 0.1 to 0.5. When R exceeds 0.5 (in other words, when τ2 is less than twice of τ1), the adhesion to the adherend when using the pressure-sensitive adhesive sheet and the releasability at the time of unnecessary use or bonding correction Coexistence of is difficult. In addition, considering coexistence of adhesion to adherend when using a pressure-sensitive adhesive sheet and releasability at the time of unnecessary use or retouching, it is desirable that R is small, but R is less than 0.1. If this is the case, the degree of anisotropy may be too high, and the allowable angle in the peeling direction may be narrowed.

  A release film or release paper is attached to the surface of the pressure-sensitive adhesive layer 3 for the purpose of protecting the pressure-sensitive adhesive layer 3, or a release agent such as silicone is applied to the surface of the substrate 1 opposite to the resin layer 2. It is common to process and roll (tape) winding. FIG. 3 shows a schematic cross-sectional view of an example of a product to which a release film (release paper) is bonded and an example of a product having a roll (tape) winding shape. In FIG. 3A, a release sheet 20 provided with a release agent layer 4 on one side of a support 5 is bonded to an anisotropic adhesive sheet 10 so that the release agent layer 4 covers the surface of the adhesive layer 3 Example. FIG. 3B shows an example in which the release agent layer 4 covers the surface of the pressure-sensitive adhesive layer 3 when the release agent layer 4 is provided on the surface of the substrate 1 opposite to the resin layer 2 and rolled. It is. The terms pressure sensitive adhesive sheet, pressure sensitive adhesive tape and pressure sensitive adhesive film are often distinguished by the presence or absence of roll, thickness and width, etc. In the present specification, the terms pressure sensitive adhesive sheet and anisotropic pressure sensitive adhesive sheet are as follows: In particular, it is used in a broad sense without distinction, and includes forms such as an adhesive tape and an adhesive film.

  Since it is necessary to fill in the depressions of the concavo-convex structure of the resin layer 2 with the adhesive layer 3, it is desirable to apply the adhesive directly to the sheet on which the substrate 1 and the resin layer 2 are laminated. Depending on the concavo-convex structure of 2 and the viscosity (polymerization degree) of the pressure-sensitive adhesive, the pressure-sensitive adhesive is applied to a release film or a release paper and then attached to the surface of the resin layer 2 of the sheet on which the substrate 1 and the resin layer 2 are laminated. You may agree. In the case of a tape-shaped product, an adhesive is applied to the surface of the base 1 side of the sheet in which the base 1 and the resin layer 2 are laminated on the surface of the base 1, and the tape is applied. You may roll it. It is also possible to provide the resin layer 2 having the cross section of the concavo-convex structure and the pressure-sensitive adhesive layer 3 filling the concavo-convex structure of the resin layer 2 on both sides of the substrate 1.

The invention will now be further described by way of examples.
Example 1
A UV-curable hard coat coating agent (Seika Beam manufactured by Dainichi Seika Kogyo Co., Ltd.) on the easily adhesive-treated side of a polyester film (ester A-1597 manufactured by Toyobo Co., Ltd.) having a thickness of 50 μm. (Registered Trademark) PET HC-301) was coated with a Mayer bar so that the thickness after drying was 8 μm, and dried in a hot air circulating oven at 100 ° C. for 1 minute to remove the solvent. After that, by rubbing a comb (hair comb of 1 mm in comb width, 0.7 mm in interval) on the hard coat coating application surface, a uniform stripe (vertical stripe pattern) is formed in the coating flow direction After that, the hard coat coating agent was cured by irradiating ultraviolet rays under the condition of the integrated light quantity of 1500 mJ / cm ² with an ultraviolet irradiator (using a metal halide lamp). In the hard coat coating layer on which the obtained groove pattern was formed, 100 parts by weight of an adhesive (one-sided oil and fat industry acrylic adhesive (AS-409) manufactured by Nippon Polyurethane Industry Co., Ltd. isocyanate-based curing agent Apply 3 parts by weight of Coronate (registered trademark) HL) to a thickness of 20 μm after drying (thickness from the surface of the polyester film to the surface of the pressure-sensitive adhesive layer) using an applicator. It was dried in a circulating oven for 2 minutes to remove the solvent in the adhesive. Then, on the surface of the pressure-sensitive adhesive layer, a separator (Mitsubishi Resin Co., Ltd. Diamond Foil MRF-25) obtained by treating a silicone-based release agent on a 25 μm-thick PET film substrate is laminated to form an anisotropic adhesive sheet. Made. The obtained anisotropic adhesive sheet was kept in a hot air circulating oven at 50 ° C. for 5 days to be aged to cure the adhesive, and the anisotropic adhesive sheet of Example 1 was produced.

(Example 2)
As an adhesive, 1 part by weight of an isocyanate-based curing agent (Corronate (registered trademark) HL) manufactured by Nippon Polyurethane Industry Co., Ltd. was added to 100 parts by weight of an acrylic adhesive (AS-409) manufactured by One Oil & Fat Industry Co., Ltd. An anisotropic pressure-sensitive adhesive sheet of Example 2 was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was changed to 16 μm using the pressure-sensitive adhesive.

(Example 3)
The same procedure as in Example 1 was repeated except that uniform grooves (horizontal stripe pattern) in the form of stripes perpendicular to the coating flow were formed by rubbing the comb (hair comb) onto the hard coat coating application surface. An anisotropic adhesive sheet of Example 3 was produced.

(Example 4)
An anisotropic adhesive sheet of Example 4 was produced in the same manner as in Example 1 except that the thickness of the pressure-sensitive adhesive layer was 12 μm.

(Comparative example 1)
A pressure-sensitive adhesive sheet of Comparative Example 1 was produced in the same manner as Example 1, except that the hard coat layer was not applied.

(Comparative example 2)
By rubbing a comb (hair comb) on the hard coat coating application surface, the coating flow direction and the direction perpendicular to the coating flow are provided with uniform grooves (stripe pattern) in the form of stripes, respectively. In the same manner as Example 1, a pressure-sensitive adhesive sheet of Comparative Example 2 was produced.

(Comparative example 3)
A pressure-sensitive adhesive sheet of Comparative Example 3 was produced in the same manner as Example 1, except that the thickness of the pressure-sensitive adhesive layer was 9 μm.

Hereinafter, methods and results of the evaluation test are shown.
<Method of measuring adhesion of anisotropic adhesive sheet and adhesive sheet>
From the anisotropic adhesive sheet or adhesive sheet, a sample (25 mm in width, 150 mm in length) in a direction parallel to (longitudinal) and perpendicular to (horizontal) in the coating flow direction is collected. The sample separator is peeled off and bonded to a glass plate using a 2 kg rubber roller. After standing for 1 hour in a test environment of 23 ° C. × 50% RH, the strength when peeling off the sample is measured in the direction of 180 ° at a peeling rate of 300 mm / min using a tensile tester, and this is used as the sample Adhesive force (N / 25 mm).

<Method of measuring surface roughness (arithmetic mean surface roughness Ra) of adhesive>
The sample separator was peeled off, and the surface roughness (arithmetic mean surface roughness Ra) of the pressure-sensitive adhesive layer surface was measured in a noncontacting manner at a magnification of 5 times with a laser microscope (LEXT OLS4000 manufactured by Olympus Corporation), n = The average value of three measurements was taken as the surface roughness of the sample.

About the anisotropic adhesive sheet of the obtained Examples 1-4, and the adhesive sheet of Comparative Examples 1-3, the measurement result measured was shown in Table 1 and Table 2. The “pattern layer” in Tables 1 and 2 is a resin layer formed from a hard coat coating agent.
In Comparative Examples 1 and 2, since there is no anisotropy of the resin pattern, R is taken as adhesive strength (longitudinal) / adhesive strength (horizontal) for convenience.

From the measurement results shown in Tables 1 and 2, the following can be understood.
The anisotropic adhesive sheet of Examples 1 to 4 according to the present invention exhibits different adhesive strength (peelability) depending on the peeling direction in the longitudinal and lateral directions. On the other hand, the adhesive sheet of Comparative Example 1 in which the resin layer was not provided and the adhesive sheet of Comparative Example 2 in which the resin layer was plaided were not affected by the peeling direction in the longitudinal and lateral directions, and both had substantially the same adhesive force (peelability It became). In addition, the adhesion of Comparative Example 3 in which the surface of the pressure-sensitive adhesive layer is not smooth (the ratio K of the thickness T1 of the thinnest portion to the thickness T2 of the thickest portion of the thickness of the pressure-sensitive adhesive layer is 0.1) The sheet was also not affected by the longitudinal and transverse peeling directions, and both had substantially the same adhesive strength (peelability).

The present invention provides an anisotropic adhesive sheet which adheres firmly to an adherend at the time of use and can be easily peeled off from the adherend at the time of unnecessary use or at the time of bonding correction.
The anisotropic adhesive sheet according to the present invention is not restricted by the materials of the base and the adhesive, and has different releasability depending on the peeling direction. Therefore, for example, various applications such as wallpaper, window film, marking sheet, label, patch, adhesive tape, address label, invoice for courier, protective film for optical film and display, protective sheet for metal plate and steel plate It can be used for

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... resin layer, 2a ... lower part of resin layer, 2b ... upper part of resin layer, 3 ... adhesive layer, 4 ... release agent layer, 5 ... support of a release sheet, 10 ... anisotropic adhesive property Sheet, 20 ... peeling sheet.

Claims (2)

A pressure-sensitive adhesive sheet in which a resin layer having a cross section of a concavo-convex structure is formed on at least one side of a long base material, and the resin layer having a cross section of the concavo-convex structure is filled with a pressure-sensitive adhesive layer,
The pattern shape of the concavo-convex structure of the resin layer having a cross section of the concavo-convex structure is
(A) In the longitudinal direction or the width direction of the substrate, having convex portions in the form of stripes and having flat concave parts in the form of stripes, or
(B) It is formed by having convex portions in the form of streaks in oblique directions with respect to the longitudinal direction of the base material and having concave portions in the form of streaks,
The thickness T2 of the thickest portion of the pressure-sensitive adhesive layer is 5 to 100 μm, and the ratio K of the thickness T1 of the thinnest portion to the thickness T2 of the thickest portion of the thickness of the pressure-sensitive adhesive layer is K = T1 / T2 = 0.2 to 0.8,
The surface of the pressure-sensitive adhesive layer to be adhered to the adherend has an arithmetic average surface roughness Ra of 5 μm or less,
An anisotropic adhesive sheet characterized in that the adhesive strength is different depending on the direction in which the pressure-sensitive adhesive layer is peeled from the adherend after the pressure-sensitive adhesive sheet is bonded to the adherend.   When the adherend is a glass plate, the ratio R of the adhesion τ1 in the direction along the convex shape of the resin layer to the adhesion τ2 in the direction perpendicular to the convex shape of the resin layer is R = τ1 / The anisotropic adhesive sheet according to claim 1, wherein τ 2 = 0.1 to 0.5.

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